Manufacturing method of high-stability open-junction plastic-packaged silicon rectifier diode

文档序号：720129 发布日期：2021-04-16 浏览：22次中文

阅读说明：本技术 一种高稳定性开放结塑封硅整流二极管的制造方法 (Manufacturing method of high-stability open-junction plastic-packaged silicon rectifier diode ) 是由李金栋李斌于 2020-12-14 设计创作，主要内容包括：本发明公开了一种高稳定性开放结塑封硅整流二极管的制造方法,包括：步骤1,二极管晶粒的制备；步骤2,铜引线电极回火；步骤3,装填；步骤4,焊接；步骤5,清洗；步骤6,塑封。本发明方法生产的二极管,气孔面积小,良品率高,有效避免焊接不密集牢固的问题。提高产品高温下的可靠性,特别是有效改善二极管的反向稳定耐压、稳定低正向压降、高温漏电流、使用寿命等指标。(The invention discloses a manufacturing method of a high-stability open junction plastic package silicon rectifier diode, which comprises the following steps: step 1, preparing diode crystal grains; step 2, tempering the copper lead electrode; step 3, filling; step 4, welding; step 5, cleaning; and 6, plastic packaging. The diode produced by the method has small pore area and high yield, and effectively avoids the problem of low density and firmness of welding. The reliability of the product at high temperature is improved, and particularly, the indexes of reverse stable voltage resistance, stable low forward voltage drop, high-temperature leakage current, service life and the like of the diode are effectively improved.)

1. A manufacturing method of a high-stability open junction plastic package silicon rectifier diode is characterized by comprising the following steps:

step 1: preparation of diode crystal grains

1.1: pre-cutting the silicon wafer in the thickness direction to form diode crystal grains which are not completely cut, wherein the cutting depth of the silicon wafer is 2/3-3/4 of the total thickness of the silicon wafer;

1.2: placing a silicon wafer N face pre-cut in the thickness direction downwards on crystal grain cracking paper, enabling the cutting edge direction to be upward, and lightly pressing to enable diode crystal grains which are not completely cut to be completely cracked to form a wafer;

step 2: copper lead electrode tempering

Loading the two copper lead electrodes into a welding boat, and putting the welding boat into a tunnel furnace for tempering;

before tempering, opening the second-way nozzle, the third-way nozzle and the fourth-way nozzle, spraying protective gas, keeping the flow rates of the second-way nozzle, the third-way nozzle and the fourth-way nozzle at 4500-; then opening the first way of nozzles and the fifth way of nozzles to spray protective gas, wherein the flow rate of the first way of nozzles is controlled at 2500-; reducing the flow rate of the second channel of nozzles to 3000-3500L/h, and reducing the flow rates of the third channel of nozzles and the fourth channel of nozzles to 3500-4000L/h;

when the flow is confirmed to be stable, the feeding welding can be started; the protective gas sprayed out from the first path of nozzle and the fifth path of nozzle is nitrogen; and the protective gas sprayed out of the second path of nozzle, the third path of nozzle and the fourth path of nozzle is a mixed gas of nitrogen and hydrogen, wherein the molar ratio of the hydrogen to the nitrogen is 0.02: 1-0.04: 1;

tempering temperature and time: heating the welding boat to 390-400 ℃ in a heating section of a tunnel furnace at a temperature rising slope of 20 +/-0.5 ℃/min, and maintaining the temperature for a time: 5-8 min; then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 80 +/-5 ℃ at a cooling slope of 8 +/-0.5 ℃/min, and the welding boat is discharged;

and step 3: loading

Placing the two copper lead electrodes, the two soldering lugs and the wafer into a fixture after tempering; each copper lead electrode comprises a table top and a lead; the cross sections of the copper lead electrodes, the soldering lugs and the wafers are circular, and the copper lead electrodes, the soldering lugs and the wafers are coaxially arranged;

the size of the table top of each copper lead electrode is equal to that of the wafer, and the diameter of the soldering lug is slightly larger than that of the wafer; the thickness of the soldering lug is 0.04-0.06 mm;

and 4, step 4: welding of

Putting the filled welding boat into the tunnel furnace again for welding to form a diode welding part;

before starting the furnace, opening the second-way nozzle, the third-way nozzle and the fourth-way nozzle to spray protective gas, keeping the flow rates of the second-way nozzle, the third-way nozzle and the fourth-way nozzle at 4500-; then opening the first way of nozzles and the fifth way of nozzles to spray protective gas, wherein the flow rate of the first way of nozzles is controlled at 2500-; reducing the flow rate of the second channel of nozzles to 2500-;

when the flow is confirmed to be stable, the feeding welding can be started; the protective gas is nitrogen; the welding temperature and time were: heating the welding boat to 330-340 ℃ in a heating section of the tunnel furnace at a temperature rising slope of 16.5 +/-0.5 ℃/min, and maintaining the welding temperature for a time of: 8-10 min; then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 70 +/-5 ℃ at a cooling slope of 5.0 +/-0.5 ℃/min, the welding boat is taken out of the furnace, and finally the welding boat is naturally cooled to the room temperature;

and 5: cleaning of

The method comprises the following steps:

5.5: soaking the diode welding piece in absolute ethyl alcohol;

5.6: drying the diode welding part;

step 6: plastic package

2. The method for manufacturing the high-stability open-junction plastic-packaged silicon rectifier diode according to claim 1, wherein the method comprises the following steps: during tempering, smearing a rosin isopropanol solution on the surface of the copper lead electrode; in the rosin isopropanol solution, the mass ratio of rosin to isopropanol is 1: 10-15.

3. The method for manufacturing the high-stability open-junction plastic-packaged silicon rectifier diode according to claim 1, wherein the method comprises the following steps: when the air in the hearth is thoroughly flushed away by the introduced protective gas, the time for ejecting the gas from the second path of nozzles, the third path of nozzles and the fourth path of nozzles is not less than 40 minutes.

4. The method for manufacturing the high-stability open-junction plastic-packaged silicon rectifier diode according to claim 1, wherein the method comprises the following steps: and 6, coating the plastic packaging material on the part with the wafer, to which the diode is welded, by using a die and a press, and only exposing the two leads to the outside to realize the packaging and molding of the diode.

5. The method for manufacturing the high-stability open-junction plastic-packaged silicon rectifier diode according to claim 4, wherein the method comprises the following steps: the plastic packaging material comprises an adhesive and a filler, wherein the adhesive is epoxy resin, and the filler is quartz powder; the volume ratio of the adhesive to the filler was 4: 1.

6. The method for manufacturing the high-stability open-junction plastic-packaged silicon rectifier diode according to claim 1, wherein the method comprises the following steps: the hardness of the lead after tempering is controlled between 0.9N and 1.1N.

7. The method for manufacturing the high-stability open-junction plastic-packaged silicon rectifier diode according to claim 1, wherein the method comprises the following steps: the weight percentage of the soldering lug is as follows: lead: 92.5%, tin: 5%, silver: 2.5 percent.

8. The method for manufacturing the high-stability open-junction plastic-packaged silicon rectifier diode according to claim 1, wherein the method comprises the following steps: the welding furnace is in a structural form that an inlet is an ascending slope and an outlet is a descending slope.

9. The method for manufacturing the high-stability open-junction plastic-packaged silicon rectifier diode according to claim 1, wherein the method comprises the following steps: the diameter of the lead was 0.6 mm.

10. The method for manufacturing the high-stability open-junction plastic-packaged silicon rectifier diode according to claim 1, wherein the method comprises the following steps: the white glue is an epoxy plastic packaging material, before gluing, the epoxy plastic packaging material is taken out of a refrigeration house and then is not unpacked, the 'clear glue' is stored for 14-16 hours at room temperature, the unpacked package needs to be placed for 0.5-1 hour after being unpacked, the temperature of the package is consistent with the ambient temperature, then preheating is carried out, the preheating temperature is 80-90 ℃, and when the molding material is changed from gray black to paint black, plastic packaging is carried out within 5 seconds.

Technical Field

The invention relates to the manufacture of a semiconductor diode, in particular to a method for manufacturing a high-stability diode.

Background

In addition, the upper and lower graphite boats must have a considerable concentricity in the prior art, and the concentricity of the upper and lower leads of the poor concentricity welded material is difficult to guarantee, so that at least the following disadvantages are caused: a, sizing is difficult to apply, and material breakage can occur in severe cases; b-molding subjects the wafer to undesirable bonding stresses (which can increase IR and decrease PIV), and in severe cases, can cause die cracking, especially in SKY and GPP devices. Since the front side bonding pads of these two types of devices are severely limited, poor concentricity, in addition to the above-mentioned disadvantages, can cause solder to overflow the bonding pads and cause short circuits or LP. The prior art lacks a good method for controlling concentricity.

In the prior art, the structure of an open junction plastic package silicon rectifier diode is shown in fig. 1 and fig. 2. The ideal bonding surface should be pore-free, but in practice tunnel furnace bonded devices always have some porosity. Two conditions must be met for the creation of weld porosity: (1) gas exists on the welding surface or gas is generated (2) on the welding surface during welding, and the gas cannot escape from the welding surface until the soldering tin is solidified (liquid phase is changed into solid phase).

The gas source forming the gas vent mainly comes from three aspects: A. because the lead table, the soldering lug and the chip cannot be absolutely and closely contacted during filling, namely certain nitrogen gas always exists; B. the oxide films on the surfaces of the lead, the soldering lug and the nickel coating are reduced by hydrogen to generate water vapor; C. the flux decomposes the generated gas. The bubbles present in the weld surface move slowly by gravity to escape the weld surface, but this is related to the speed of travel of the material in the welding furnace (chain speed), a certain chain speed defining the time during which the material is in the hot zone, once the material has exited the hot zone, the material begins to cool and the solder resolidifies, and the bubbles that have not yet moved out of the weld surface are no longer present, which is the mechanism of weld porosity formation.

The damage of the existence of the welding air hole to the electrical property of the device is mainly reflected in two aspects: A. for the damage to the forward direction, the existence of the air holes reduces the effective area of the wafer, so that the forward resistance is increased, the corresponding thermal resistance is also increased, VF is increased, and the bearable forward surge current is reduced. B. In the past, it was thought that poor welding adversely affects only the forward direction, but that poor welding adversely affects the reverse direction even more than the forward direction. The reverse performance depends on the degree of cleanliness of the side surfaces of the crystal grains, if too many edge air holes exist on the welding surface, the tiny gap becomes a place for storing dirt on the table surface of the wafer, once various conductive impurities generated in acid cleaning enter the air holes, the conductive impurities are difficult to clean, as long as the dirt does not run to the vicinity of the P-N junction, the reverse electrical performance of the device does not show any bad property, but the dirt can escape from the small holes under the action of heat, an electric field and the like and run to the vicinity of the P-N junction, the reverse characteristic of the device is deteriorated (electrical degradation), and the main reason that the electrical quality of the device is deteriorated with time is achieved.

In addition, the copper lead electrode is generally made of oxygen-free copper, and because the process conditions during drawing the copper lead electrode into a wire are inconsistent, the hardness of some oxygen-free copper leads is higher, so that the diode can cause large compressive stress to the wafer during forming and curing, the reverse current IR passing through the surface of the P-N junction can be increased if the diode is light, and the wafer can be damaged and completely fails if the diode is heavy.

Acid cleaning is a key process in the process of plastic packaging the diode, and the reverse electrical property of the diode is formed by the acid cleaning process without considering the influence of the problems of the wafer. We take a welded O/J series material to measure its forward and reverse characteristics, and find that its forward voltage drop is satisfactory, which means that its forward characteristics are possessed, but its reverse characteristics are SHORT-circuit (SHORT) like, so the P-N junction of the wafer has been formed earlier, and its forward characteristics are possessed, so it does not present the reverse characteristics, so from the basic principle of semiconductor P/N junction, we mentioned that the P/N junction has forward and reverse characteristics, but it only means that the current IR (body) flowing through the P-N junction is exposed around the wafer for an O/J (open junction-P/N junction is directly exposed on the surface) device, and when a reverse voltage is applied, the current IR (body) inside the P/N junction is consistent with the reverse characteristics of the P-N junction, however, there is also a reverse current IR (surface) through the P-N junction surface, i.e. the total reverse IR (surface) is strongly related to the topography around the wafer: IR = IR (bulk) + IR (surface) wafer fabrication is to make a large P-N junction on a large wafer and then cut into grains of the desired size. In the prior art, the purpose of acid cleaning of plastic-sealed silicon rectifier diodes (O/J series diodes) of open junctions from an N surface to a P surface is to solve a mechanical damage layer generated during wafer cracking. When the wafer etching boundary after the etching is carefully observed, it is found that the wafer etching boundary before the etching (cross-sectional view) is a middle dotted line position in which the upper and lower portions coincide with each other, but the wafer etching boundary after the etching is changed as shown in fig. 3.

The reason for shaping the wafer acid etch boundary is: the reaction of the mixed acid and the silicon firstly oxidizes the silicon into silicon dioxide through the oxidation of the nitric acid on the silicon, and then the silicon dioxide is removed by hydrofluoric acid, so the speed of the nitric acid oxidation reaction determines the overall corrosion speed of the silicon, and the speed of the oxidation speed is related to the quantity of free electrons in the silicon material, the more the free electrons are, the faster the oxidation reaction is. However, the structure of the diode chip is divided by the conductivity type, which is N⁺A strong N-type region, an N region and a P region, wherein the N + region has the most free electrons, the N region is the next to the N region, the P region is the least to the N region⁺The more free electrons near the surface, and conversely the less free electrons near the surface, the P-region, so that the etch rates of the regions on the wafer side are not uniform, which ultimately results in the wafer erosion boundary shown in fig. 3. The acid etching boundary of the wafer is N⁺The region forms a circle of grooves extending inwards, a plurality of pits (products after edge air holes are corroded) are formed in the grooves, and the grooves and the pits are difficult to clean. The groove and pit pickling process is characterized by that when the groove and pit pickling process is implemented, a certain quantity of conductive dirt is fed into said small space, and when the groove and pit pickling process is implemented, the ultrasonic cleaning process is difficult to clean it, so that it can be used as the hidden trouble for making the device fail, after the ultrasonic cleaning process is implemented, the dirt is far from P-N junction, so that it has no any interference to electric property, and can be stored for a long time, or can be baked at high temp. or acted by electric field, and can be moved toward P-N junction from small hole, so that it is the good device at that time, and can be failed later.

The patent with publication number CN102214570A discloses a method for manufacturing a high-stability trigger diode, which comprises the steps of welding, primary acid washing, high-purity water washing, secondary acid washing, high-purity water washing, two-pass high-purity water ultrasonic cleaning, two-pass absolute ethyl alcohol cleaning, gluing, injection molding and the like; the inlet of the welding furnace is designed into an uphill structure, and the outlet is designed into a downhill structure, so that the consumption of protective gas nitrogen during welding is obviously reduced, and the energy consumption is reduced; the existing scattered method is changed into the method of putting acid liquor at a fixed point, so that the consumption of acid is reduced, the pollution to the environment is reduced, and the copper lead is reducedCorroding; impurities can be effectively removed by adopting a fan-shaped nozzle washing mode in the cleaning process; two times of ultrasonic cleaning with high-purity water and two times of cleaning with absolute ethyl alcohol are adopted, so that the high-temperature performance of the product is greatly improved. Primary acid washing, wherein the acid washing solution is as follows: HF: HNO₃∶HAC∶H₂SO₄Etching to remove the mechanical damage layer of the scribing at the ratio of 9:12:4 for h₃Comprises the following steps: h is not more than 135 seconds₃Less than or equal to 155 seconds; (5) and (3) washing the diode material obtained in the step (4) with high-purity water for a washing time h 4: h is less than or equal to 50 seconds₄Less than or equal to 70 seconds; (6) carrying out secondary acid washing on the diode material obtained in the step (5), wherein the acid washing solution is as follows: h₃PO₄∶H₂O₂∶H₂Cleaning at 1: 2: 3O and t₃Comprises the following steps: t3 is more than or equal to 58 ℃ and less than or equal to 62 ℃ for h₅Comprises the following steps: h is less than or equal to 50 seconds₅Less than or equal to 60 seconds; (7) washing the diode material obtained in the step (6) with high-purity water for h₅Comprises the following steps: h is less than or equal to 50 seconds₆Less than or equal to 70 seconds.

The patent with the publication number of CN104399702A discloses a diode chip wafer acid cleaning process, which sequentially comprises primary acid cleaning, secondary acid cleaning, ammonia water and hydrogen peroxide cleaning and water ultrasonic cleaning, wherein the primary acid cleaning time is 110-125s, and the secondary acid cleaning time is 70-78 s; the cleaning solution of the primary acid washing is HNO₃、HF、CH₃COOH and H₂SO₄The cleaning solution of the secondary acid cleaning is H₃PO₄、H₂O₂、H₂O and CH₃A mixture of COOH; HNO in the primary pickling solution₃:HF:CH₃COOH and H₂The volume ratio of SO4 is 9:9:12: 4; h in the secondary pickling solution₃PO4、H₂O₂、H₂O and CH₃The volume ratio of COOH was 1:0.8:3: 0.2. The invention has the advantages that: in the acid washing process, glacial acetic acid is added into the secondary acid washing liquid, and the product lead sulfate in the mixed acid washing is dissolved by utilizing the glacial acetic acid, so that the lead sulfate is prevented from being adsorbed to the side surface of the chip, and the electrical property of the diode chip wafer is improved. None of the above patents consider the effects of grooves and pits during the pickling process.

Disclosure of Invention

The invention aims to provide a manufacturing method of an open junction plastic package silicon rectifier diode, which solves the problems that the concentricity guarantee difficulty of upper and lower leads of a diode welding material is high, numerous pits exist in the cleaning process, the cleaning is not clean, the stress is not thoroughly eliminated and the like in the diode welding process in the prior art, and has the characteristics of high stability and long service life.

In order to achieve the above object, the present invention adopts the following technical solutions.

A manufacturing method of a high-stability open junction plastic package silicon rectifier diode is characterized by comprising the following steps:

the method comprises the following steps:

step 1: preparation of diode crystal grains

1.2: and (3) placing the silicon wafer N face pre-cut in the thickness direction downwards on the crystal grain cracking paper, and slightly pressing the silicon wafer N face upwards to ensure that the diode crystal grains which are not completely cut are completely cracked to form the wafer.

Step 2: copper lead electrode tempering

Loading the two copper lead electrodes into a welding boat, and putting the welding boat into a tunnel furnace for tempering;

the protective gas nozzles of the tunnel furnace are provided with five paths, the first path of nozzles are arranged at a feed inlet of the tunnel furnace, the fifth path of nozzles are arranged at a discharge outlet of the tunnel furnace, the second path of nozzles and the third path of nozzles are respectively arranged at the bottom and the upper part of a heating section of the tunnel furnace, and the fourth path of nozzles are arranged at a cooling section of the tunnel furnace; the first way of nozzle and the fifth way of nozzle are used for sealing a door, namely, the hearth is separated from the outside by a nitrogen curtain, so that outside air is prevented from entering the hearth, and the second way of nozzle, the third way of nozzle and the fourth way of nozzle only really play a role in protection.

Before tempering every time, opening the second-way nozzle, the third-way nozzle and the fourth-way nozzle, spraying protective gas, keeping the flow rates of the second-way nozzle, the third-way nozzle and the fourth-way nozzle at 4500 liters/hour, closing the first-way nozzle and the fifth-way nozzle at the moment, and thoroughly removing air in the hearth by the introduced protective gas; then opening a first path of nozzles and a fifth path of nozzles to spray protective gas, wherein the flow rate of the first path of nozzles is 2500 liters/hour, and the flow rate of the fifth path of nozzles is 2500 liters/hour; reducing the flow rate of the second path of nozzles to 3000 liters/hour, and reducing the flow rates of the third path of nozzles and the fourth path of nozzles to 3500 liters/hour;

tempering temperature and time: heating the welding boat to 390 ℃ in a heating section of a tunnel furnace at a temperature rising slope of 20 ℃/min, and maintaining the temperature for a time: 5 min; and then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 80 ℃ at a cooling slope of 8 ℃/min, and the welding boat is discharged from the furnace.

And step 3: loading

the size of the mesa of each copper lead electrode is equal to the size of the wafer, and the diameter of the soldering lug is slightly larger than that of the wafer. The thickness of the soldering lug is 0.04-0.06 mm.

And 4, step 4: welding of

Putting the filled welding boat into the tunnel furnace again for welding to form a diode welding part;

when the flow is confirmed to be stable, the feeding welding can be started; the protective gas is nitrogen.

The welding temperature and time were: heating the welding boat to 330-340 ℃ in a heating section of the tunnel furnace at a temperature rising slope of 16.5 +/-0.5 ℃/min, and maintaining the welding temperature for a time of: 8-10 min; and then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is cooled to 70 +/-5 ℃ at a cooling slope of 5.0 +/-0.5 ℃/min, the welding boat is taken out of the furnace, and finally the welding boat is naturally cooled to the room temperature.

And 5: cleaning of

The method comprises the following steps:

5.1: according to the volume ratio of nitric acid with the concentration of more than 68 percent, hydrofluoric acid with the concentration of more than 48 percent, glacial acetic acid with the concentration of more than 99 percent and sulfuric acid with the concentration of more than 98 percent = 10: 95-105: 11-12: 2-3, mixing and stirring to obtain No. 1 solution; the pickling temperature of the No. 1 liquid must not exceed 28 ℃; pickling the welded diode welding piece by using mixed acid for 130-150 seconds, and then washing the diode welding piece by using deionized water; in the process of flushing the diode welding piece, the flushing nozzle swings back and forth; controlling the temperature of the deionized water at 15-30 ℃; the pickling temperature of the No. 1 liquid is not more than 28 ℃, and when the room temperature is higher than 28 ℃, a temperature reduction measure is adopted. The corrosion of silicon by mixed acids is a chemical process, and like all chemical processes, its reaction rate is strongly temperature dependent. The higher the temperature, the faster the reaction speed. Above 28 degrees celsius, the etching rate can result in a relatively sharp trench at the wafer acid etching boundary, and pitting occurs on the trench, which is detrimental to electrical performance. When the water temperature is lower than 15 ℃, the solubility of various impurities in water is reduced, the cleaning is difficult, and when the water temperature is higher than 30 ℃, impurities in the water container material can be dissolved into the water, so that the device is polluted. In the process of flushing the diode welding piece, the flushing nozzle swings back and forth; the washing nozzle swings back and forth, and the groove is easy to clean.

5.2: phosphoric acid at a concentration of 85 ± 1%: hydrogen peroxide with concentration of 35 +/-1%: hydrofluoric acid at a concentration > 48%: 2-hydroxyphosphonoacetic acid: pure water was mixed at a volume ratio = 10: 15-20: 2-3:1-2: 30, mixing and stirring to obtain No. 2 liquid, wherein the temperature of the No. 2 liquid is not more than 30 ℃, cleaning the diode welding piece in the acid washing liquid for 50-60 seconds, and then washing with deionized water; and in the process of flushing the diode welding piece, the flushing nozzle swings back and forth. In the process of flushing the diode welding piece, the flushing nozzle swings back and forth; white foam should appear in the reaction, and the solution is light blue after the reaction; at the excessively low temperature, the complex oxidation effect is obviously reduced. The temperature of the deionized water is controlled between 15 and 30 ℃. When the water temperature is lower than 15 ℃, the solubility of various impurities in water is reduced, the cleaning is difficult, and when the water temperature is higher than 30 ℃, impurities in the water container material can be dissolved into the water, so that the device is polluted. In the process of flushing the diode welding piece, the flushing nozzle swings back and forth; the washing nozzle swings back and forth, and the groove is easy to clean.

5.3: ammonia water with the concentration of 25-28%, hydrogen peroxide with the concentration of 35 +/-1% and pure water are mixed according to the volume ratio of 5-6: 1: uniformly mixing the materials in a proportion of 12 to 14 to prepare No. 3 liquid, heating the No. 3 liquid to 60 to 65 ℃, and cleaning the diode welding piece for 50 to 60 seconds by using the No. 3 liquid; the diode welds were then rinsed with deionized water at temperatures above 65 ℃. And in the process of flushing the diode welding piece, the flushing nozzle swings back and forth. Alkaline substances are relatively acidic and difficult to clean, a greasy feeling always exists when a soap, a detergent and the like are used for washing hands at ordinary times, ammonia water is alkaline, and the material treated by the ammonia water is washed by ionic water at the temperature of over 65 ℃, so that the cleaning effect is good.

5.5: and soaking the diode welding piece in methanol.

5.6: and drying the diode welding piece.

Step 6: plastic package

As a preferred technical scheme, during tempering, a rosin isopropanol solution is coated on the surface of a copper lead electrode; in the rosin isopropanol solution, the volume ratio of rosin to isopropanol is 1: 10-15. The reduction of rosin acid decomposed at high temperature is utilized.

As a preferred technical scheme, when the air in the hearth is thoroughly flushed by the introduced protective gas, the time for ejecting the gas from the second path of nozzles, the third path of nozzles and the fourth path of nozzles is not less than 40 minutes.

In step 6, a die and a press are used to coat the plastic package material on the part with the chip where the diode is welded, and only two leads are exposed to realize the encapsulation molding of the diode.

According to a preferable technical scheme, the plastic package material comprises an adhesive and a filler, wherein the adhesive is epoxy resin, and the filler is quartz powder; the volume ratio of the adhesive to the filler was 4: 1.

Preferably, the hardness of the tempered lead is controlled to be 0.9-1.1.

As a preferred technical scheme, the soldering lug comprises the following components in percentage by weight: lead: 92.5%, tin: 5%, silver: 2.5 percent.

As a preferred technical scheme, the welding furnace is in a structural form that an inlet is an ascending slope and an outlet is a descending slope.

As a preferred technical scheme, the diameter of the lead is 0.6 mm.

As a preferred technical scheme, the white glue is an epoxy plastic packaging material, before gluing, the epoxy plastic packaging material is taken out from a refrigeration house and then is not unpacked, the 'clear glue' is stored for 14-16 hours at room temperature, the box is placed for 0.5-1 hour after being unpacked, the temperature of the box is consistent with the ambient temperature, then preheating is carried out, the preheating temperature is 80-90 ℃, and when the molding material is changed from gray black to paint black, plastic packaging is carried out within 5 seconds.

The invention has the beneficial effects that:

1. the concentricity control problem in the welding process is solved. Firstly, the N surface of a silicon wafer precut in the thickness direction is downward, when cracking, the crack is usually far away from the position of a P/N junction compared with the N surface, the damage degree consistency of each side surface close to the P-N is better, and a circle of groove extending inwards is not easily formed in an N + area of a graph 3 when pickling on the next step. And secondly, a tempering process is arranged, the temperature is rapidly raised, the temperature is slowly lowered, nitrogen is used for protection, and hydrogen is used for reducing oxides on the surface of the copper lead electrode, so that welding stress does not exist basically. Through the tempering treatment, the copper lead electrode does not cause large compressive stress to the wafer when the molding solidification (if the wafer is subjected to large compressive stress, the IR is increased if the wafer is light, and the wafer is broken and completely fails if the wafer is heavy). Since the surface of the lead, particularly the surface thereof in contact with the flux, has a thin oxide film, which is disadvantageous for soldering, the oxide film is removed by the small amount of hydrogen contained in the shielding gas during tempering (by utilizing the reducing property of hydrogen at high temperature: H)₂+CuO=Cu+H₂O). The welding stress is reduced, and the concentricity problem in the welding process is favorably solved. Thirdly, the size of the table top of each copper lead electrode is equal to that of the wafer, and the diameter of the soldering lug is slightly larger than that of the wafer; the soldering lug 2 automatically shrinks under the action of surface tension after being melted, automatically aligns the centroid of the table top of the copper lead electrode and the centroid of the wafer, and can be well attached to the wafer 3 and the table top 12, thereby ensuring the stability of the performance of the diode tube core. The thickness of the soldering lug is 0.04-0.06mm, the welding quality below 0.04mm is not guaranteed, and the thickness is above 0.06mm, so that the solder flows easily to cause short circuit.

3. In the acid cleaning process, the amount of acetic acid in the No. 1 solution is increased, so that the effect of buffering and slowing down the corrosion speed is realized, and the obvious grooves formed on the wafer by acid etching are favorably formed. The addition of sulfuric acid is to protect the metal parts by utilizing the strong water absorption of concentrated sulfuric acid so as to avoid excessive corrosion of lead soldering tin. Although concentrated sulfuric acid is added into the mixed acid to protect the lead and the soldering tin, the lead and the soldering tin are corroded as little as possible, in fact, a considerable part of metals are corroded, the metals generally appear in the form of salts, during acid pickling of a rapid device, even a precious metal simple substance (gold or platinum is doped in the rapid device) can appear, the solubility of the heavy metal salt of copper, lead and tin in water is low, solid deposition can be separated out when the local concentration is high (after acid etching, white deposits on the lead and the wafer are often seen in subsequent treatment, namely lead acetate), and the metal salt or the precious metal simple substance can cause fatal damage to the electrical property if the metal salt or the precious metal simple substance is left on the acid etching boundary of the wafer. Although concentrated sulfuric acid is added into the solution 1 to protect the lead and the soldering tin, and corrosion is minimized, in fact, a considerable part of metals are corroded, and the metals generally appear in the form of salts, during acid cleaning of a rapid device, even a precious metal simple substance (gold or platinum is doped in the rapid device) can appear, the solubility of the heavy metal salts of copper, lead and tin in water is low, solid deposition can be separated out when the local concentration is high (after acid cleaning, white deposits on the lead and a wafer are often seen in subsequent treatment, namely lead acetate), and whether the metal salts or the precious metal simple substance are remained on a table top, the metal salts or the precious metal simple substance can cause fatal damage to the electrical property. The main function of the liquid 2 and the liquid 3 is to make the metal ions complex into a complex with high solubility in water by utilizing the complexation of the metal ions, so that the heavy metal ions can be removed in the subsequent water washing. The liquid No. 2 has another function of generating a layer of silicon dioxide passivation protective film on the surface of fresh silicon by utilizing the strong oxidizing property of phosphoric acid and hydrogen peroxide. Hydrofluoric acid is added into the No. 2 liquid to complete further corrosion of the silicon oxidation, oxide film removal, reoxidation and oxide film removal. The 2-hydroxyphosphonoacetic acid is widely used for scale inhibition and corrosion inhibition of circulating cooling water systems in the industries of steel, petrifaction, electric power, medicine and the like, and is suitable for low-hardness water quality in the south of China, and the HPAA can be widely used for scale inhibition and corrosion inhibition of circulating cooling water systems in the industries of steel, petrifaction, electric power, medicine and the like, is suitable for low-hardness water quality in the south of China, and has a scale inhibition effect. 2-hydroxyphosphonoacetic acid is added, and the reaction temperature is controlled below 30 ℃, because in midsummer, generally speaking, when the temperature of the room-temperature water is higher than 30 ℃, pitting often appears on the corrosion table; the 2-hydroxyphosphonoacetic acid can play a good role in buffering and slowing down the corrosion speed and reducing the generation of pockmarks. At the excessively low temperature, the complex oxidation effect is obviously reduced, white foams appear in the normal reaction, and the solution is light blue after the reaction. The addition of a small amount of hydrogen peroxide into the No. 3 solution can enhance the activity of ammonia water to play a good role in catalysis, so that the complexing effect of the ammonia water is enhanced. In the process of flushing the diode welding piece, the flushing nozzle swings back and forth; the washing nozzle swings back and forth, and the groove is easy to clean. The No. 1 liquid and the No. 2 liquid are subjected to acid washing twice, and oxidation, oxidation film removal, reoxidation and reoxidation film removal of silicon can be completed by regulating and controlling the components and the temperature of the No. 1 liquid and the No. 2 liquid, and as can be seen by comparing fig. 4 and fig. 5, the generation of pits is effectively reduced. Compared with the conventional effect, the cleaning liquid preparation and the cleaning process are more favorable for ensuring the surface smoothness and flatness of the P/N junction, and can effectively reduce the electric leakage of the body surface of the P/N junction so as to ensure the stability of the performance of the diode tube core.

4. In the prior art, isopropanol and ethanol clean the diode. Ethanol (CH)₃CH₂OH) is colorless and transparent liquid with special fragrance, is volatile, has lower density than water, and can be mutually dissolved with water in any ratio. Is an important solvent and can dissolve various organic matters and inorganic matters. Isopropanol (C)₃H₈O), commonly known as IPA, is a colorless, transparent liquid with an odor similar to a mixture of ethanol and acetone. Is an important chemical product and raw material. It is mainly used as dehydrating agent and cleaning agent in pharmacy, cosmetics, plastics, perfume, paint and electronic industry. In the present invention, methanol is used for the washing. The purpose of cleaning by using methanol is two: 1. by means of a "dehydration" treatment of the material; 2. while the surface tension of water is high, the impurities left in the fine gaps may be difficult to escape, and the surface tension of methanol is low, which facilitates the impurities to enter the fine gaps and be carried out. 3. The performance-price ratio is far better than that of isopropanol and ethanol.

5. The invention is stored at room temperature for 14-16 hours, the temperature of the mold material is consistent with the environment temperature (not only the surface temperature of the epoxy material), the mold material is balanced with the environment temperature, the surface of the mold material has no water accumulation, the internal and external temperatures are easy to be consistent during preheating, and the phenomenon of half-cooked as described above can not occur. In order to balance the humidity of the material and the surrounding environment, the material needs to be placed for 0.5 to 1 hour after the sealing bag is opened. Preheating is controlled to be generally controlled to be increased to 80-90 ℃, which can be controlled by high-frequency output power and heating time, at the moment, the molding compound is changed from gray black to paint black, attention must be paid to close fit in time, the preheated material must be injected as soon as possible, the aim is to achieve material equal glue, the interval time of the material equal glue must not exceed 5 seconds, and the plastic packaging effect is good.

The diode produced by the method has the advantages that the air hole area is greatly reduced (the air hole area is less than 8 percent), the yield is 95-100 percent, and the problem of incompact and firm welding is effectively avoided. The reliability of the product at high temperature is improved, particularly, the indexes of reverse stable voltage resistance, stable low forward voltage drop, high-temperature leakage current, service life and the like of the diode can be effectively improved, the service life can be more than 10 years, and the product has more competitive advantages.

Drawings

Fig. 1 is a schematic structural diagram of an open junction plastic package silicon rectifier diode in the prior art.

FIG. 2 is a schematic view showing the structure of a copper lead electrode in example 1.

FIG. 3 is a schematic illustration of the wafer acid etch boundary after the prior art acid etch.

Fig. 4 is a picture of a solder vent of a diode using a conventional soldering process.

Fig. 5 is a picture of the solder vent of a diode using the soldering process of the present invention.

Wherein: 1 is a copper lead electrode; 11 is a table top, and 12 is a lead; 2 is solder; 3 is a wafer; 4 is white glue; 5 is an epoxy molding compound.

Detailed Description

Example 1. A manufacturing method of a high-stability open junction plastic package silicon rectifier diode comprises the following steps:

step 1: preparation of diode crystal grains

1.1: and pre-cutting the silicon wafer in the thickness direction to form incompletely-cut diode crystal grains, wherein the cutting depth of the silicon wafer is 2/of the total thickness of the silicon wafer.

Step 2: copper lead electrode tempering

Loading the two copper lead electrodes into a welding boat, and putting the welding boat into a tunnel furnace for tempering;

Before tempering every time, opening the second-way nozzle, the third-way nozzle and the fourth-way nozzle, spraying protective gas, keeping the flow rates of the second-way nozzle, the third-way nozzle and the fourth-way nozzle at 4500 liters/hour, closing the first-way nozzle and the fifth-way nozzle at the moment, and thoroughly removing air in the hearth by the introduced protective gas; then opening a first path of nozzles and a fifth path of nozzles to spray protective gas, wherein the flow rate of the first path of nozzles is controlled at 2000 liters/hour, and the flow rate of the fifth path of nozzles is controlled at 2500 liters/hour; reducing the flow rate of the second path of nozzles to 2500 liters/hour, and reducing the flow rates of the third path of nozzles and the fourth path of nozzles to 3000 liters/hour;

tempering temperature and time: heating the welding boat to 390 ℃ in a heating section of a tunnel furnace at a temperature rising slope of 20.5 ℃/min, and maintaining the temperature for a time: 5 min; then the welding boat is sent to the cooling section of the tunnel furnace, and the temperature is reduced to 85 ℃ at the cooling slope of 8.5 ℃/minAnd (4) discharging at the temperature of. Since the surface of the lead, particularly the surface thereof in contact with the flux, has a thin oxide film, which is disadvantageous for soldering, the oxide film is removed by the small amount of hydrogen contained in the shielding gas during tempering (by utilizing the reducing property of hydrogen at high temperature: H)₂+CuO=Cu+H₂O). Washing with deionized water, drying and removing the oxide film. The lead is made of oxygen-free copper, the texture of the lead is soft, the wafer can not cause large compressive stress when the wafer is molded and solidified (if the wafer is subjected to large compressive stress, IR can be increased when the wafer is light, and the wafer can be damaged when the wafer is heavy so as to completely fail), but the lead is also made of oxygen-free copper, the process conditions during drawing the lead into a wire are inconsistent, the hardness of some oxygen-free copper leads is larger, the lead is treated by annealing, the wire diameter is 0.6mm, the hardness after annealing is controlled to be 0.9, and the stress is basically not existed.

And step 3: loading

Placing the two tempered copper lead electrodes 1, the two soldering lugs 2 and the wafer 3 into a tool clamp; each copper lead electrode comprises a table board 12 and a lead 11; the cross sections of the copper lead electrodes 1, the soldering lugs 2 and the wafers 3 are circular, and the copper lead electrodes 1, the soldering lugs 2 and the wafers 3 are coaxially arranged;

as shown in fig. 2, the size of the mesa 12 of each copper lead electrode is equal to the size of the wafer 3, and the ratio of the diameter of the tab 2 to the diameter of the wafer 3 is 1.02: 1; by adopting the structure, the soldering lug 2 can be well attached to the wafer 3 and the table-board 12 under the action of surface tension after being melted; the thickness of the soldering lug is 0.06mm, and the soldering tin material is easy to overflow the welding area to cause short circuit.

And 4, step 4: welding of

Putting the filled welding boat into the tunnel furnace again for welding to form a diode welding part;

before starting the furnace, opening the second-path nozzle, the third-path nozzle and the fourth-path nozzle to spray protective gas, keeping the flow rates of the second-path nozzle, the third-path nozzle and the fourth-path nozzle at 4500L/h, closing the first-path nozzle and the fifth-path nozzle at the moment, and completely removing air in the furnace cavity by the introduced protective gas; then opening a first path of nozzles and a fifth path of nozzles to spray protective gas, wherein the flow rate of the first path of nozzles is controlled at 2000 liters/hour, and the flow rate of the fifth path of nozzles is controlled at 2500 liters/hour; reducing the flow rate of the second path of nozzles to 2500 liters/hour, and reducing the flow rates of the third path of nozzles and the fourth path of nozzles to 3000 liters/hour;

when the flow is confirmed to be stable, the feeding welding can be started; the protective gas is nitrogen.

The welding temperature and time were: heating the welding boat to 330 ℃ in a heating section of a tunnel furnace at a temperature rising slope of 16.5 ℃/min, maintaining the welding temperature for a time: 8 min; and then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 65 ℃ at a cooling slope of 5.0 ℃/min, the welding boat is taken out of the furnace, and finally the welding boat is naturally cooled to the room temperature.

And 5: cleaning of

The method comprises the following steps:

5.1: according to the volume ratio of nitric acid with the concentration of more than 68 percent, hydrofluoric acid with the concentration of more than 48 percent, glacial acetic acid with the concentration of more than 99 percent and sulfuric acid with the concentration of more than 98 percent = 10: 95: 11: 2 mixing and stirring to obtain No. 1 solution; the pickling temperature of the No. 1 liquid must not exceed 28 ℃; pickling the welded diode welding piece for 130 seconds by using mixed acid, and then washing the diode welding piece by using deionized water; in the process of flushing the diode welding piece, the flushing nozzle swings back and forth; controlling the temperature of the deionized water at 15 ℃; the pickling temperature of the No. 1 liquid is not more than 28 ℃, and when the room temperature is higher than 28 ℃, a temperature reduction measure is adopted. The corrosion of silicon by mixed acids is a chemical process, and like all chemical processes, its reaction rate is strongly temperature dependent. The higher the temperature, the faster the reaction speed. Above 28 degrees celsius, the etching rate can result in a relatively sharp trench at the wafer acid etching boundary, and pitting occurs on the trench, which is detrimental to electrical performance. When the water temperature is lower than 15 ℃, the solubility of various impurities in water is reduced, the cleaning is difficult, and when the water temperature is higher than 30 ℃, impurities in the water container material can be dissolved into the water, so that the device is polluted. In the process of flushing the diode welding piece, the flushing nozzle swings back and forth; the washing nozzle swings back and forth, and the groove is easy to clean.

5.2: phosphoric acid at a concentration of 84%: hydrogen peroxide with a concentration of 34%: hydrofluoric acid at a concentration > 48%: 2-hydroxyphosphonoacetic acid: pure water was mixed at a volume ratio = 10: 15: 2:1: 30, mixing and stirring to obtain No. 2 liquid, wherein the temperature of the No. 2 liquid is not more than 30 ℃, cleaning the diode welding piece in the acid washing liquid for 50-60 seconds, and then washing with deionized water; and in the process of flushing the diode welding piece, the flushing nozzle swings back and forth. White foam should appear in the reaction, and the solution is light blue after the reaction; at the excessively low temperature, the complex oxidation effect is obviously reduced. The temperature of the deionized water was controlled at 15 ℃. When the water temperature is lower than 15 ℃, the solubility of various impurities in water is reduced, the cleaning is difficult, and when the water temperature is higher than 30 ℃, impurities in the water container material can be dissolved into the water, so that the device is polluted. In the process of flushing the diode welding piece, the flushing nozzle swings back and forth; the washing nozzle swings back and forth, and the groove is easy to clean.

5.3: ammonia water with the concentration of 25%%, hydrogen peroxide with the concentration of 35 +/-1% and pure water are mixed according to the volume ratio of 5: 1: uniformly mixing the materials in a proportion of 12 to 14 to prepare No. 3 liquid, heating the No. 3 liquid to 60 ℃, and cleaning the diode welding piece for 50 seconds by using the No. 3 liquid; the diode welds were then rinsed with deionized water at temperatures above 65 ℃. And in the process of flushing the diode welding piece, the flushing nozzle swings back and forth. Alkaline substances are relatively acidic and difficult to clean, a greasy feeling always exists when a soap, a detergent and the like are used for washing hands at ordinary times, ammonia water is alkaline, and the cleaning effect is good if the material treated by the ammonia water is used at a temperature of over 65 ℃.

5.5: and soaking the diode welding piece in methanol. The purpose of cleaning by using methanol is two: 1. by means of a "dehydration" treatment of the material; 2. while the surface tension of water is high, the impurities left in the fine gaps may be difficult to escape, and the surface tension of methanol is low, which facilitates the impurities to enter the fine gaps and be carried out. 3. The performance-price ratio is far better than that of isopropanol and ethanol.

5.6: and drying the diode welding piece.

Compared with the prior art, the method increases the amount of acetic acid in the No. 1 solution, and the effect of reducing the corrosion speed by seven buffers is beneficial to reducing the formation of grooves on the wafer by acid etching. The addition of sulfuric acid is to protect the metal parts by utilizing the strong water absorption of concentrated sulfuric acid so as to avoid excessive corrosion of lead soldering tin. Although concentrated sulfuric acid is added into the mixed acid to protect the lead and the soldering tin, the lead and the soldering tin are corroded as little as possible, in fact, a considerable part of metals are corroded, the metals generally appear in the form of salts, during acid pickling of a rapid device, even a precious metal simple substance (gold or platinum is doped in the rapid device) can appear, the solubility of the heavy metal salt of copper, lead and tin in water is low, solid deposition can be separated out when the local concentration is high (after acid etching, white deposits on the lead and the wafer are often seen in subsequent treatment, namely lead acetate), and the metal salt or the precious metal simple substance can cause fatal damage to the electrical property if the metal salt or the precious metal simple substance is left on the acid etching boundary of the wafer. The main function of the liquid 2 and the liquid 3 is to make the metal ions complex into a complex with high solubility in water by utilizing the complexation of the metal ions, so that the heavy metal ions can be removed in the subsequent water washing. The liquid No. 2 has another function of generating a layer of silicon dioxide passivation protective film on the surface of fresh silicon by utilizing the strong oxidizing property of phosphoric acid and hydrogen peroxide. Hydrofluoric acid is added into the No. 2 liquid and has the function of dissolving lead sulfate generated in the reaction process of the No. 1 liquid. The use temperature should be controlled at 70-75 ℃, the complex oxidation effect is obviously reduced at the excessively low temperature, white foam should appear in the normal reaction, and the solution is light blue after the reaction. The addition of a small amount of hydrogen peroxide into the No. 3 solution can enhance the activity of ammonia water to play a good role in catalyzing, so that the complexing effect is enhanced, and the solution is obviously dark blue after contacting with the material, which is the typical color of copper ions.

Step 6: plastic package

And 6, coating the plastic packaging material on the part with the wafer, to which the diode is welded, by using a die and a press, and only exposing the two leads to the outside to realize the packaging and molding of the diode.

The plastic packaging material comprises an adhesive and a filler, wherein the adhesive is epoxy resin, and the filler is quartz powder; the volume ratio of the adhesive to the filler was 4: 1. The hardness of the wire after tempering was controlled to 0.9. The weight percentage of the soldering lug is as follows: lead: 92.5%, tin: 5%, silver: 2.5 percent. The welding furnace is in a structural form that an inlet is an ascending slope and an outlet is a descending slope. The thickness of the soldering lug is 0.06 mm. The diameter of the lead was 0.6 mm. The white glue is an epoxy plastic packaging material, before gluing, the epoxy plastic packaging material is taken out of a refrigeration house and then is not unpacked, the epoxy plastic packaging material is stored at room temperature for 14 hours, the white glue is placed for 0.5 hour after the packaging material is unpacked, the temperature of the packaging material is consistent with the ambient temperature, then preheating is carried out, the preheating temperature is 80 ℃, and when the molding material is changed from grey black to paint black, plastic packaging is carried out within 5 seconds.

Example 2. A manufacturing method of a high-stability open junction plastic package silicon rectifier diode is characterized by comprising the following steps:

the method comprises the following steps:

step 1: preparation of diode crystal grains

1.1: pre-cutting the silicon wafer in the thickness direction to form incompletely-cut diode crystal grains, wherein the cutting depth of the silicon wafer is 3/4 of the total thickness of the silicon wafer;

Step 2: copper lead electrode tempering

Loading the two copper lead electrodes into a welding boat, and putting the welding boat into a tunnel furnace for tempering;

Before tempering every time, opening the second-way nozzle, the third-way nozzle and the fourth-way nozzle, spraying protective gas, keeping the flow rates of the second-way nozzle, the third-way nozzle and the fourth-way nozzle at 4500 liters/hour, closing the first-way nozzle and the fifth-way nozzle at the moment, and thoroughly removing air in the hearth by the introduced protective gas; then opening a first way of nozzles and a fifth way of nozzles to spray protective gas, wherein the flow rate of the first way of nozzles is 2500 liters/hour, and the flow rate of the fifth way of nozzles is 3000 liters/hour; reducing the flow rate of the second path of nozzles to 2500-;

tempering temperature and time: heating the welding boat to 400 ℃ in a heating section of the tunnel furnace at a temperature rising slope of 19.5 ℃/min, and maintaining the temperature for 8 min; and then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 75 ℃ at a cooling slope of 7.5 ℃/min, and the welding boat is discharged from the furnace.

And step 3: loading

as shown in fig. 2, the size of the mesa 12 of each copper lead electrode is equal to the size of the wafer 3, and the ratio of the diameter of the tab 2 to the diameter of the wafer 3 is 1.01: 1; with this structure, the soldering lug 2 can be well bonded with the wafer 3 and the table-board 12 under the action of surface tension after being melted. The thickness of the soldering lug is 0.04 mm.

And 4, step 4: welding of

Putting the filled welding boat into the tunnel furnace again for welding to form a diode welding part;

before starting the furnace, opening the second-path nozzle, the third-path nozzle and the fourth-path nozzle, spraying protective gas, keeping the flow rates of the second-path nozzle, the third-path nozzle and the fourth-path nozzle 5500 liters/hour, closing the first-path nozzle and the fifth-path nozzle at the moment, and completely removing air in the furnace chamber by the introduced protective gas; then opening a first path of nozzles and a fifth path of nozzles to spray protective gas, wherein the flow rate of the first path of nozzles is 2500 liters/hour, and the flow rate of the fifth path of nozzles is 2500 liters/hour; reducing the flow rate of the second path of nozzles to 2500 liters/hour, and reducing the flow rates of the third path of nozzles and the fourth path of nozzles to 3000 liters/hour;

when the flow is confirmed to be stable, the feeding welding can be started; the protective gas is nitrogen.

The welding temperature and time were: heating the welding boat to 330 ℃ in a heating section of a tunnel furnace at a temperature rising slope of 16 ℃/min, maintaining the welding temperature for a time: 8 min; and then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 65 ℃ at a cooling slope of 4.5 ℃/min, the welding boat is taken out of the furnace, and finally the welding boat is naturally cooled to the room temperature.

And 5: cleaning of

The method comprises the following steps:

5.1: according to the volume ratio of nitric acid with the concentration of more than 68 percent, hydrofluoric acid with the concentration of more than 48 percent, glacial acetic acid with the concentration of more than 99 percent and sulfuric acid with the concentration of more than 98 percent = 10: 105: 11: 2 mixing and stirring to obtain No. 1 solution; the pickling temperature of the No. 1 liquid must not exceed 28 ℃; pickling the welded diode welding piece for 130 seconds by using mixed acid, and then washing the diode welding piece by using deionized water; in the process of flushing the diode welding piece, the flushing nozzle swings back and forth; controlling the temperature of the deionized water at 15 ℃; the pickling temperature of the No. 1 liquid is not more than 28 ℃, and when the room temperature is higher than 28 ℃, a temperature reduction measure is adopted. The corrosion of silicon by mixed acids is a chemical process, and like all chemical processes, its reaction rate is strongly temperature dependent. The higher the temperature, the faster the reaction speed. Above 28 degrees celsius, the etching rate can result in a relatively sharp trench at the wafer acid etching boundary, and pitting occurs on the trench, which is detrimental to electrical performance. When the water temperature is lower than 15 ℃, the solubility of various impurities in water is reduced, the cleaning is difficult, and when the water temperature is higher than 30 ℃, impurities in the water container material can be dissolved into the water, so that the device is polluted. In the process of flushing the diode welding piece, the flushing nozzle swings back and forth; the washing nozzle swings back and forth, and the groove is easy to clean.

5.2: phosphoric acid at a concentration of 84%: hydrogen peroxide with a concentration of 34%: hydrofluoric acid at a concentration > 48%: 2-hydroxyphosphonoacetic acid: pure water was mixed at a volume ratio = 10: 18: 2.5:1.5: 30, mixing and stirring to obtain No. 2 liquid, wherein the temperature of the No. 2 liquid is not more than 30 ℃, cleaning the diode welding piece in the acid washing liquid for 50-60 seconds, and then washing with deionized water; and in the process of flushing the diode welding piece, the flushing nozzle swings back and forth. White foam should appear in the reaction, and the solution is light blue after the reaction; at the excessively low temperature, the complex oxidation effect is obviously reduced. The temperature of the deionized water was controlled at 15 ℃. When the water temperature is lower than 15 ℃, the solubility of various impurities in water is reduced, the cleaning is difficult, and when the water temperature is higher than 30 ℃, impurities in the water container material can be dissolved into the water, so that the device is polluted. In the process of flushing the diode welding piece, the flushing nozzle swings back and forth; the washing nozzle swings back and forth, and the groove is easy to clean.

5.3: ammonia water with the concentration of 25%%, hydrogen peroxide with the concentration of 34% and pure water are mixed according to the volume ratio of 6: 1:12 to obtain No. 3 liquid, heating the No. 3 liquid to 60 ℃, and cleaning the diode welding piece for 50 seconds by using the No. 3 liquid; the diode welds were then rinsed with deionized water at temperatures above 65 ℃.

5.5: and soaking the diode welding piece in methanol.

5.6: and drying the diode welding piece.

Step 6: plastic package

And (3) coating white glue on the radial peripheral surfaces of the wafer and the table top of the diode welding part after cleaning and drying, and carrying out diode packaging and forming after the white glue is solidified to obtain a finished product. The white glue is an epoxy plastic packaging material, before gluing, the epoxy plastic packaging material is taken out of a refrigeration house without unpacking, the glue is stored at room temperature for 16 hours, the unpacked bag needs to be placed for 1 hour after being opened, the temperature of the unpacked bag is consistent with the ambient temperature, then preheating is carried out, the preheating temperature is 90 ℃, and when the molding material is changed from grey black to paint black, plastic packaging is carried out within 5 seconds.

During tempering, smearing a rosin isopropanol solution on the surface of the copper lead electrode; in the rosin isopropanol solution, the mass ratio of rosin to isopropanol is 1: 10. When the air in the hearth is thoroughly flushed away by the introduced protective gas, the time for ejecting the gas from the second path of nozzles, the third path of nozzles and the fourth path of nozzles is not less than 40 minutes.

The rest is the same as example 1.

Example 3. A manufacturing method of a high-stability open junction plastic package silicon rectifier diode comprises the following steps:

step 1: preparation of diode crystal grains

1.1: pre-cutting the silicon wafer in the thickness direction to form incompletely-cut diode crystal grains, wherein the cutting depth of the silicon wafer is 2/3 of the total thickness of the silicon wafer;

Step 2: copper lead electrode tempering

Loading the two copper lead electrodes into a welding boat, and putting the welding boat into a tunnel furnace for tempering;

Before tempering every time, opening the second-way nozzle, the third-way nozzle and the fourth-way nozzle, spraying protective gas, keeping the flow rates of the second-way nozzle, the third-way nozzle and the fourth-way nozzle at 4500 liters/hour, closing the first-way nozzle and the fifth-way nozzle at the moment, and thoroughly removing air in the hearth by the introduced protective gas; then opening a first path of nozzles and a fifth path of nozzles to spray protective gas, wherein the flow rate of the first path of nozzles is controlled at 2000 liters/hour, and the flow rate of the fifth path of nozzles is controlled at 2500 liters/hour; reducing the flow rate of the second path of nozzles to 2500 liters/hour, and reducing the flow rates of the third path of nozzles and the fourth path of nozzles to 3000 liters/hour;

when the flow is confirmed to be stable, the feeding welding can be started; the protective gas sprayed out from the first path of nozzle and the fifth path of nozzle is nitrogen; the protective gas sprayed out of the second path of nozzle, the third path of nozzle and the fourth path of nozzle is a mixed gas of nitrogen and hydrogen, wherein the molar ratio of the hydrogen to the nitrogen is 0.03: 1;

tempering temperature and time: heating the welding boat to 400 ℃ in a heating section of a tunnel furnace at a temperature rising slope of 20.5 ℃/min, and maintaining the temperature for a time: 8 min; and then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 85 ℃ at a cooling slope of 8.5 ℃/min, and the welding boat is discharged from the furnace.

And step 3: and (4) filling. Placing the two tempered copper lead electrodes 1, the two soldering lugs 2 and the wafer 3 into a tool clamp; each copper lead electrode comprises a table board 12 and a lead 11; the cross sections of the copper lead electrodes 1, the soldering lugs 2 and the wafers 3 are circular, and the copper lead electrodes 1, the soldering lugs 2 and the wafers 3 are coaxially arranged;

as shown in fig. 2, the size of the mesa 12 of each copper lead electrode is equal to the size of the wafer 3, and the ratio of the diameter of the tab 2 to the diameter of the wafer 3 is 1.008: 1; by adopting the structure, the soldering lug 2 can be well attached to the wafer 3 and the table-board 12 under the action of surface tension after being melted;

and 4, step 4: and (6) welding. Putting the filled welding boat into the tunnel furnace again for welding to form a diode welding part;

before starting the furnace, opening the second-path nozzle, the third-path nozzle and the fourth-path nozzle, spraying protective gas, keeping the flow rates of the second-path nozzle, the third-path nozzle and the fourth-path nozzle 5500 liters/hour, closing the first-path nozzle and the fifth-path nozzle at the moment, and completely removing air in the furnace chamber by the introduced protective gas; then opening a first way of nozzles and a fifth way of nozzles to spray protective gas, wherein the flow rate of the first way of nozzles is 2500 liters/hour, and the flow rate of the fifth way of nozzles is 3000 liters/hour; reducing the flow rate of the second path of nozzles to 3000 liters/hour, and reducing the flow rates of the third path of nozzles and the fourth path of nozzles to 3500 liters/hour; when the flow is confirmed to be stable, the feeding welding can be started; the protective gas is nitrogen.

The welding temperature and time were: heating the welding boat to 340 ℃ in a heating section of a tunnel furnace at a heating slope of 17 ℃/min, and maintaining the welding temperature for: 10 min; and then conveying the welding boat to a cooling section of a tunnel furnace, cooling to 75 ℃ at a cooling slope of 5 DEG.5 ℃/min, discharging, and finally naturally cooling to room temperature.

And 5: and (5) cleaning. The method comprises the following steps: 5.1: according to the volume ratio of nitric acid with the concentration of more than 68 percent, hydrofluoric acid with the concentration of more than 48 percent, glacial acetic acid with the concentration of more than 99 percent and sulfuric acid with the concentration of more than 98 percent = 10: 105: 11: 3 mixing and stirring to obtain No. 1 solution; the pickling temperature of the No. 1 liquid must not exceed 28 ℃; pickling the welded diode welding piece for 150 seconds by using mixed acid, and then washing the diode welding piece by using deionized water; in the process of flushing the diode welding piece, the flushing nozzle swings back and forth; controlling the temperature of the deionized water at 30 ℃; the pickling temperature of the solution 1 should not exceed 28 ℃.

5.2: phosphoric acid at a concentration of 85 ± 1%: hydrogen peroxide with a concentration of 36%: hydrofluoric acid at a concentration > 48%: 2-hydroxyphosphonoacetic acid: pure water was mixed at a volume ratio = 10: 20: 3:2: 30, mixing and stirring to obtain a No. 2 liquid, wherein the temperature of the No. 2 liquid is not more than 30 ℃, cleaning the diode welding piece in the acid washing liquid for 60 seconds, and then washing with deionized water; and in the process of flushing the diode welding piece, the flushing nozzle swings back and forth.

5.3: ammonia water with the concentration of 28%, hydrogen peroxide with the concentration of 36% and pure water are mixed according to the volume ratio of 6: 1: 14 to obtain No. 3 liquid, heating the No. 3 liquid to 65 ℃, and cleaning the diode welding piece for 60 seconds by using the No. 3 liquid; the diode welds were then rinsed with deionized water at temperatures above 65 ℃.

5.5: and soaking the diode welding piece in methanol.

5.6: and drying the diode welding piece.

Step 6: and (5) plastic packaging. And cleaning and drying the wafer of the diode welding part and the radial peripheral surface of the table board, and curing the white glue to perform diode packaging and forming to obtain a finished product. The soldering lug is 0.04mm thick.

The rest is the same as example 1.

Example 4. A manufacturing method of a high-stability open junction plastic package silicon rectifier diode is characterized by comprising the following steps:

the method comprises the following steps:

step 1: preparation of diode crystal grains

Step 2: copper lead electrode tempering

Loading the two copper lead electrodes into a welding boat, and putting the welding boat into a tunnel furnace for tempering;

Before tempering every time, opening the second-way nozzle, the third-way nozzle and the fourth-way nozzle, spraying protective gas, keeping the flow rates of the second-way nozzle, the third-way nozzle and the fourth-way nozzle at 4500 liters/hour, closing the first-way nozzle and the fifth-way nozzle at the moment, and thoroughly removing air in the hearth by the introduced protective gas; then opening a first way of nozzles and a fifth way of nozzles to spray protective gas, wherein the flow rate of the first way of nozzles is 2500 liters/hour, and the flow rate of the fifth way of nozzles is 3000 liters/hour; reducing the flow rate of the second path of nozzles to 3500 liters/hour, and reducing the flow rates of the third path of nozzles and the fourth path of nozzles to 4000 liters/hour;

tempering temperature and time: heating the welding boat to 395 ℃ in a heating section of a tunnel furnace at a temperature rising slope of 20.5 ℃/min, and maintaining the temperature for a time: 9 min; and then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 75 ℃ at a cooling slope of 5.5 ℃/min, and the welding boat is discharged from the furnace.

as shown in fig. 2, the size of the mesa 12 of each copper lead electrode is equal to the size of the wafer 3, and the ratio of the diameter of the tab 2 to the diameter of the wafer 3 is 1.012: 1; with this structure, the soldering lug 2 can be well bonded with the wafer 3 and the table-board 12 under the action of surface tension after being melted.

And 4, step 4: and (6) welding. Putting the filled welding boat into the tunnel furnace again for welding to form a diode welding part;

before starting the furnace, opening the second-path nozzle, the third-path nozzle and the fourth-path nozzle, spraying protective gas, keeping the flow rates of the second-path nozzle, the third-path nozzle and the fourth-path nozzle 5500 liters/hour, closing the first-path nozzle and the fifth-path nozzle at the moment, and completely removing air in the furnace chamber by the introduced protective gas; then opening a first way of nozzles and a fifth way of nozzles to spray protective gas, wherein the flow rate of the first way of nozzles is controlled at 2000 liters/hour, and the flow rate of the fifth way of nozzles is controlled at 2800 liters/hour; reducing the flow rate of the second path of nozzles to 2500 liters/hour, and reducing the flow rates of the third path of nozzles and the fourth path of nozzles to 3200 liters/hour;

when the flow is confirmed to be stable, the feeding welding can be started; the protective gas is nitrogen.

The welding temperature and time were: heating the welding boat to 340 ℃ in a heating section of a tunnel furnace at a temperature rising slope of 16 ℃/min, and maintaining the welding temperature for a time: 10 min; and then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 75 ℃ at a cooling slope of 7.0 ℃/min, the welding boat is taken out of the furnace, and finally the welding boat is naturally cooled to the room temperature.

And 5: cleaning of

The method comprises the following steps: 5.1: according to the volume ratio of nitric acid with the concentration of more than 68 percent, hydrofluoric acid with the concentration of more than 48 percent, glacial acetic acid with the concentration of more than 99 percent and sulfuric acid with the concentration of more than 98 percent = 10: 105: 11: 2 mixing and stirring to obtain No. 1 solution; the pickling temperature of the No. 1 liquid must not exceed 28 ℃; pickling the welded diode welding piece for 150 seconds by using mixed acid, and then washing the diode welding piece by using deionized water; in the process of flushing the diode welding piece, the flushing nozzle swings back and forth; the temperature of the deionized water was controlled at 30 ℃.

5.2: phosphoric acid at a concentration of 85 ± 1%: hydrogen peroxide with a concentration of 36%: hydrofluoric acid at a concentration > 48%: 2-hydroxyphosphonoacetic acid: pure water was mixed at a volume ratio = 10: 19: 2.5:1.3: 30, mixing and stirring to obtain a No. 2 liquid, wherein the temperature of the No. 2 liquid is not more than 30 ℃, cleaning the diode welding piece in the acid washing liquid for 60 seconds, and then washing with deionized water; and in the process of flushing the diode welding piece, the flushing nozzle swings back and forth. White foam should appear in the reaction, and the solution is light blue after the reaction; at the excessively low temperature, the complex oxidation effect is obviously reduced.

5.4: ultrasonically or megasonically cleaning the cleaned diode welding piece in deionized water, and then washing the diode welding piece by using the deionized water with the temperature of more than 60 ℃; 5.5: and soaking the diode welding piece in methanol. 5.6: and drying the diode welding piece.

Step 6: and (5) plastic packaging. And (3) coating white glue on the radial peripheral surfaces of the wafer and the table top of the diode welding part after cleaning and drying, and carrying out diode packaging and forming after the white glue is solidified to obtain a finished product.

During tempering, smearing a rosin isopropanol solution on the surface of the copper lead electrode; in the rosin isopropanol solution, the volume ratio of rosin to isopropanol is 1: 15. When the air in the hearth is thoroughly flushed away by the introduced protective gas, the time for ejecting the gas from the second path of nozzles, the third path of nozzles and the fourth path of nozzles is not less than 40 minutes.

The rest is the same as example 1.

Example 5. A manufacturing method of a high-stability open junction plastic package silicon rectifier diode is characterized by comprising the following steps:

the method comprises the following steps:

step 1: preparation of diode crystal grains

Step 2: copper lead electrode tempering

Loading the two copper lead electrodes into a welding boat, and putting the welding boat into a tunnel furnace for tempering;

Before tempering every time, opening the second-way nozzle, the third-way nozzle and the fourth-way nozzle, spraying protective gas, keeping the flow rates of the second-way nozzle, the third-way nozzle and the fourth-way nozzle at 4500 liters/hour, closing the first-way nozzle and the fifth-way nozzle at the moment, and thoroughly removing air in the hearth by the introduced protective gas; then opening a first way of nozzles and a fifth way of nozzles to spray protective gas, wherein the flow rate of the first way of nozzles is 2200 liters/hour, and the flow rate of the fifth way of nozzles is 2800 liters/hour; reducing the flow rate of the second path of nozzles to 3200 liters/hour, and reducing the flow rates of the third path of nozzles and the fourth path of nozzles to 4000 liters/hour;

tempering temperature and time: heating the welding boat to 400 ℃ in a heating section of a tunnel furnace at a temperature rising slope of 20.5 ℃/min, and maintaining the temperature for a time: 5 min; and then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 85 ℃ at a cooling slope of 8.5 ℃/min, and the welding boat is discharged from the furnace.

And step 3: loading

as shown in fig. 2, the mesa 12 of each copper lead electrode has a size equal to that of the wafer 3, and the ratio of the diameter of the tab 2 to the diameter of the wafer 3 is 1.009: 1; by adopting the structure, the soldering lug 2 can be well attached to the wafer 3 and the table-board 12 under the action of surface tension after being melted;

and 4, step 4: and (6) welding. Putting the filled welding boat into the tunnel furnace again for welding to form a diode welding part;

before starting the furnace, opening the second way of nozzle, the third way of nozzle and the fourth way of nozzle, spraying out protective gas, keeping the flow rates of the second way of nozzle, the third way of nozzle and the fourth way of nozzle at 4800L/h, closing the first way of nozzle and the fifth way of nozzle at the moment, and thoroughly removing the air in the hearth by the introduced protective gas; then opening a first way of nozzles and a fifth way of nozzles to spray protective gas, wherein the flow rate of the first way of nozzles is 2200 liters/hour, and the flow rate of the fifth way of nozzles is 3000 liters/hour; reducing the flow rate of the second path of nozzles to 2500 liters/hour, and reducing the flow rates of the third path of nozzles and the fourth path of nozzles to 3500 liters/hour; when the flow is confirmed to be stable, the feeding welding can be started; the protective gas is nitrogen.

The welding temperature and time were: heating the welding boat to 340 ℃ in a heating section of a tunnel furnace at a heating slope of 17 ℃/min, and maintaining the welding temperature for: 10 min; and then the welding boat is sent to a cooling section of the tunnel furnace, the temperature is reduced to 75 ℃ at a cooling slope of 7.5 ℃/min, the welding boat is taken out of the furnace, and finally the welding boat is naturally cooled to the room temperature.

And 5: cleaning of

The method comprises the following steps:

5.2: phosphoric acid at a concentration of 85%: hydrogen peroxide with concentration of 35%: hydrofluoric acid at a concentration > 48%: 2-hydroxyphosphonoacetic acid: pure water was mixed at a volume ratio = 10: 19: 2:1: 30, mixing and stirring to obtain a No. 2 liquid, wherein the temperature of the No. 2 liquid is not more than 30 ℃, cleaning the diode welding piece in the acid washing liquid for 55 seconds, and then washing with deionized water; in the process of flushing the diode welding piece, the flushing nozzle swings back and forth; white foam should appear in the reaction, and the solution is light blue after the reaction; at the excessively low temperature, the complex oxidation effect is obviously reduced.

5.3: ammonia water with the concentration of 26%, hydrogen peroxide water with the concentration of 35% and pure water are mixed according to the volume ratio of 6: 1: 14 to obtain a No. 3 liquid, heating the No. 3 liquid to 63 ℃, and cleaning the diode welding piece for 55 seconds by using the No. 3 liquid; the diode welds were then rinsed with deionized water at temperatures above 65 ℃.

During tempering, smearing a rosin isopropanol solution on the surface of the copper lead electrode; in the rosin isopropanol solution, the volume ratio of rosin to isopropanol is 1: 12. When the air in the hearth is thoroughly flushed away by the introduced protective gas, the time for ejecting the gas from the second path of nozzles, the third path of nozzles and the fourth path of nozzles is not less than 40 minutes.

The rest is the same as example 1.

The diode parameters obtained in examples 1 to 5 were compared with the yield of the 1N4007 test and the HTRB high temperature test as follows:

after the process is adopted, the welding tension is detected to be 5KG on average. The material breakage (OPEN), the solder joint (SHORT), and the tensile force are only evaluated on a shallow level of the welding quality, and the high-level evaluation should be the weld porosity. 4-5, the linearity of the vent is less than 1/10 of the linearity of the weld face; the sum of the areas of the air holes is less than 1/10 of the welding surface; . The large area reduction of the air holes improves the quality of the product.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, and the scope of the invention should not be limited to the embodiments described above.

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Manufacturing method of high-stability open-junction plastic-packaged silicon rectifier diode

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