阅读说明：本技术 一种半导体器件金锡焊接后的清洗方法 (Cleaning method for semiconductor device after gold-tin soldering ) 是由 张智聪 孙钱 于 2020-06-24 设计创作，主要内容包括：本发明公开了一种半导体器件金锡焊接后的清洗方法,包括：一、将金锡焊接后的半导体器件浸泡在清洗液中；二、将半导体器件浸泡在装有纯水的水槽内,除去半导体器件上的清洗液；三、将半导体器件浸泡在纯水溶液中,除去半导体器件上的纯水；四、采用热风来风干半导体器件,除去半导体器件上的纯水。本发明的清洗方法通过步骤(一)、(二)和(三)的相互配合,有效除去金锡焊接后的助焊剂及其他污染物质,提高半导体器件的可靠性。(The invention discloses a cleaning method of a semiconductor device after gold-tin soldering, which comprises the following steps: firstly, soaking a semiconductor device welded by gold and tin in cleaning solution; soaking the semiconductor device in a water tank filled with pure water, and removing the cleaning liquid on the semiconductor device; thirdly, soaking the semiconductor device in pure water solution to remove pure water on the semiconductor device; and fourthly, air-drying the semiconductor device by adopting hot air to remove the pure water on the semiconductor device. The cleaning method of the invention effectively removes the soldering flux and other pollutants after gold-tin soldering by the mutual matching of the step (I), (II) and (III), thereby improving the reliability of the semiconductor device.)

1. A cleaning method for a semiconductor device after gold-tin soldering is characterized by comprising the following steps:

soaking a semiconductor device subjected to gold-tin soldering in a cleaning solution, wherein the cleaning solution comprises at least one of a water-based cleaning solution, a semi-water-based cleaning solution and a hydrocarbon cleaning solution;

the water-based cleaning solution comprises sodium metasilicate, sodium hydroxide, sodium carbonate, ethylene oxide propylene oxide copolymer, carboxymethyl cellulose, a fluorine-containing surfactant, a complexing agent, an organic silicon defoaming agent and deionized water;

the semi-aqueous cleaning solution comprises tripropylene glycol butyl ether, diethylene glycol butyl ether, methoxy methyl butanol, tetrahydrofurfuryl alcohol, benzyl alcohol, N-methyl pyroli ketone, N-ethyl pyroli ketone and alkali, wherein the alkali is one or more of amine, imide or inorganic alkali salt, silicate or phosphate;

soaking the semiconductor device in a water tank filled with pure water, and removing the cleaning liquid on the semiconductor device;

and thirdly, air-drying the semiconductor device by adopting hot air to remove pure water on the semiconductor device.

2. The method for cleaning the semiconductor device after gold-tin soldering according to claim 1, wherein in the step (one), 1 liter of the water-based cleaning solution comprises 30-80 g of sodium metasilicate, 10-30 g of sodium hydroxide, 20-50 g of sodium carbonate, 30-80 g of ethylene oxide-propylene oxide copolymer, 3-10 g of carboxymethyl cellulose, 0-2 g of a fluorine-containing surfactant, 0-5 g of a complexing agent, 0-5 g of a silicone defoaming agent and the balance of deionized water.

3. The method for cleaning a semiconductor device after gold-tin soldering as claimed in claim 2, wherein in the step (one), the fluorine-containing surfactant is one or more of sodium perfluorooctanoate, potassium perfluorooctanoate and perfluorooctanoic acid;

the complexing agent is one or more of sodium citrate, EDTA (ethylene diamine tetraacetic acid) disodium and EDTA tetrasodium.

4. The method for cleaning a semiconductor device after gold-tin soldering according to any one of claims 1 to 3, wherein in the step (I), the cleaning solution further comprises an auxiliary agent, the auxiliary agent comprises at least one of a ketone substance, an alcohol substance and an ester substance, wherein the ketone substance comprises at least one of acetone and toluene isobutyl ketone; the alcohol substance comprises at least one of ethanol, propanol and butanol; the ester substance comprises at least one of ethyl acetate and butyl acetate.

5. The method for cleaning a semiconductor device after gold-tin soldering as claimed in claim 1, wherein in the step (one), the hydrocarbon cleaning agent further comprises copper and phosphorus.

6. The method for cleaning the semiconductor device after gold-tin soldering as claimed in claim 1, wherein in the step (I), the temperature of the cleaning solution is 50 ± 10 ℃, and the soaking time is 1-5 min.

7. The method for cleaning the semiconductor device after gold-tin soldering according to claim 1, wherein in step (two), the bottom of the water tank is provided with a water inlet and a water outlet, the water inlet and the water outlet are connected through a pipe, the pipe is provided with a circulating pump and a filter screen, the circulating pump pumps pure water in the water tank out of the water outlet, and the pumped pure water enters the water tank through the pipe from the water inlet, so that the pure water in the water tank is circulated.

8. The method for cleaning the semiconductor device after gold-tin soldering of claim 7, wherein the semiconductor device is immersed in the water tank for at least two water circulation cleaning times, and the time for each circulation cleaning is 1-3 min;

the flow rate of outlet water of the pure water in the water tank is 0.5-6 m/s, and the flow rate of inlet water is 0.5-5 m/s;

the pure water has the conductivity less than or equal to 2 mu s/cm and the temperature of 50 +/-10 ℃.

9. The method for cleaning the semiconductor device after gold-tin soldering according to claim 1, wherein in the step (three), the semiconductor device is dried by a high-speed hot air blower, wherein the temperature of the hot air is 30-120 ℃ and the time of the air blowing is 1-7 min.

Technical Field

The invention relates to the field of semiconductor devices, in particular to a method for cleaning a conductor device after gold and tin welding.

Background

With the gradual application of semiconductor devices in the high-power field, the heat productivity of semiconductors is higher, the heat conductivity coefficient of gold-tin soldering can reach 57 w/m.K, and the heat conductivity is the highest in solder. The welding mode of the existing industrial gold-tin welding large-scale mass production is scaling powder and reflow soldering. The flux is an auxiliary material for ensuring the smooth operation of the welding process, prevents the reoxidation of the surface during welding, reduces the surface tension of the solder and improves the welding performance.

The types of the flux used for gold-tin soldering mainly include inorganic flux, organic flux and resin flux.

Inorganic fluxes contain inorganic acids, mainly hydrochloric acid, hydrofluoric acid, etc., which must be cleaned very rigorously immediately after use, since any halide remaining on the workpiece causes severe corrosion.

The fluxing action of the organic fluxing agent is between that of the inorganic fluxing agent and that of the resin fluxing agent, and the organic fluxing agent is also an acidic and water-soluble flux. The water-soluble flux containing organic acid is based on lactic acid and citric acid.

The resin flux contains rosin as a main component.

Flux residue on semiconductor devices can present the following problems: decrease conductivity, cause migration or short circuit; non-conductive solids such as intruding into the device contact can cause poor bonding; the resin residue is excessive, and dust and sundries are adhered; affecting the reliability of the product.

The existing method is to put the semiconductor device into an ultrasonic cleaning tank with pure water for ultrasonic cleaning, and after the ultrasonic cleaning, the semiconductor device is put into an oven for baking and drying.

The above cleaning method has the following problems: 1. in the ultrasonic cleaning process, fine cracks exist between welding surfaces due to energy released by ultrasonic waves; 2. the water stain residue is remained after the water is directly used for cleaning the food in an oven.

Disclosure of Invention

The invention aims to solve the technical problem of providing a cleaning method for a semiconductor device after gold-tin soldering, which has good soldering flux removing effect, does not generate cracks on a soldering surface and does not have water stain residue.

In order to solve the technical problem, the invention provides a cleaning method of a semiconductor device after gold-tin soldering, which comprises the following steps:

soaking a semiconductor device subjected to gold-tin soldering in a cleaning solution, wherein the cleaning solution comprises at least one of a water-based cleaning solution, a semi-water-based cleaning solution and a hydrocarbon cleaning solution;

the water-based cleaning solution comprises sodium metasilicate, sodium hydroxide, sodium carbonate, ethylene oxide propylene oxide copolymer, carboxymethyl cellulose, a fluorine-containing surfactant, a complexing agent, an organic silicon defoaming agent and deionized water;

the semi-aqueous cleaning solution comprises tripropylene glycol butyl ether, diethylene glycol butyl ether, methoxy methyl butanol, tetrahydrofurfuryl alcohol, benzyl alcohol, N-methyl pyroli ketone, N-ethyl pyroli ketone and alkali, wherein the alkali is one or more of amine, imide or inorganic alkali salt, silicate or phosphate;

soaking the semiconductor device in a water tank filled with pure water, and removing the cleaning liquid on the semiconductor device;

and thirdly, air-drying the semiconductor device by adopting hot air to remove pure water on the semiconductor device.

As an improvement of the scheme, in the step (I), 1 liter of water-based cleaning solution comprises 30-80 g of sodium metasilicate, 10-30 g of sodium hydroxide, 20-50 g of sodium carbonate, 30-80 g of ethylene oxide propylene oxide copolymer, 3-10 g of carboxymethyl cellulose, 0-2 g of fluorine-containing surfactant, 0-5 g of complexing agent, 0-5 g of organosilicon defoaming agent and the balance of deionized water.

As an improvement of the above scheme, in the step (one), the fluorine-containing surfactant is one or more of sodium perfluorooctanoate, potassium perfluorooctanoate and perfluorooctanoic acid;

the complexing agent is one or more of sodium citrate, EDTA (ethylene diamine tetraacetic acid) disodium and EDTA tetrasodium.

As an improvement of the above scheme, in the step (one), the cleaning solution further includes an auxiliary agent, where the auxiliary agent includes at least one of a ketone substance, an alcohol substance, and an ester substance, where the ketone substance includes at least one of acetone and toluene isobutyl ketone; the alcohol substance comprises at least one of ethanol, propanol and butanol; the ester substance comprises at least one of ethyl acetate and butyl acetate.

As an improvement of the scheme, in the step (one), the hydrocarbon cleaning agent also comprises copper and phosphorus.

As an improvement of the scheme, in the step (I), the temperature of the cleaning solution is 50 +/-10 ℃, and the soaking time is 1-5 min.

As an improvement of the above scheme, in the step (two), a water inlet and a water outlet are arranged at the bottom of the water tank, the water inlet and the water outlet are connected through a pipeline, a circulating pump and a filter screen are arranged on the pipeline, the circulating pump pumps out pure water in the water tank from the water outlet, and the pumped pure water enters the water tank from the water inlet through the pipeline, so that the pure water in the water tank forms circulation.

As an improvement of the scheme, the semiconductor device is soaked in a water tank for at least twice water circulation cleaning, and the time of each circulation cleaning is 1-3 min;

the flow rate of outlet water of the pure water in the water tank is 0.5-6 m/s, and the flow rate of inlet water is 0.5-5 m/s;

the pure water has the conductivity less than or equal to 2 mu s/cm and the temperature of 50 +/-10 ℃.

In the third step, a high-speed hot air blower is used for air drying the semiconductor device, wherein the hot air temperature is 30-120 ℃, and the air blowing time is 1-7 min.

The implementation of the invention has the following beneficial effects:

the cleaning method of the invention adopts a cleaning agent to remove the soldering flux and other pollutants after gold and tin soldering through the mutual matching of the steps (I), (II) and (III), and the water-based cleaning agent utilizes the wetting, emulsifying, permeating, dispersing, solubilizing and other actions of a fluorine-containing surfactant, an emulsifier (carboxymethyl cellulose), a penetrant (ethylene oxide propylene oxide copolymer) and the like to dissolve inorganic soldering flux; compared with the narrow-cut hydrocarbon cleaning agent, the hydrocarbon cleaning agent disclosed by the invention is composed of a chemical composition, is low in toxicity, low in odor and good in solubility, and can effectively dissolve organic components in the soldering flux; the semi-water-based cleaning solution effectively dissolves rosin in the resin scaling powder; the cleaning solution disclosed by the invention can effectively remove the influence of the soldering flux and other pollutants on the semiconductor device, and meanwhile, the gold-tin eutectic crystal and the semiconductor device are not damaged, so that the reliability of the semiconductor device is improved.

According to the invention, the semiconductor device is dried by hot air, so that continuous operation can be realized, and the cleaning efficiency is improved; in addition, the hot air is adopted to air-dry the semiconductor device, and other impurities on the semiconductor device can be blown away, so that the reliability of the semiconductor device is further improved; secondly, the semiconductor device is air-dried by hot air, and the hot air with lower temperature can be adopted in the same time, so that the influence of higher heating temperature on the special semiconductor device is avoided.

Drawings

FIG. 1 is a schematic view of the structure of the water tank in step (II) of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.

The invention provides a cleaning method for a semiconductor device after gold-tin soldering, which comprises the following steps:

firstly, soaking a semiconductor device subjected to gold-tin soldering in a cleaning solution to remove soldering flux;

it should be noted that, for cleaning different types of flux, different cleaning liquids are required. Specifically, the inorganic scaling powder is cleaned by water-based cleaning fluid;

the organic scaling powder is cleaned by adopting a hydrocarbon type cleaning fluid;

the cleaning resin scaling powder adopts semi-water-based cleaning liquid.

The water-based cleaning solution comprises sodium metasilicate, sodium hydroxide, sodium carbonate, ethylene oxide propylene oxide copolymer, carboxymethyl cellulose, a fluorine-containing surfactant, a complexing agent, an organic silicon defoaming agent and deionized water.

The hydrocarbon cleaning agent comprises a component with a structural formula of C_nH_2n+2Is an isomeric hydrocarbon of the formula C_nH_2n+2Normal hydrocarbon with structural formula C_nH_2nOne or more compounds of cyclane and aromatic hydrocarbon.

The semi-aqueous cleaning solution comprises tripropylene glycol butyl ether, diethylene glycol butyl ether, methoxy methyl butanol, tetrahydrofurfuryl alcohol, benzyl alcohol, N-methyl pyroli ketone, N-ethyl pyroli ketone and alkali, wherein the alkali is one or more of amine, imide or inorganic alkali salt, silicate or phosphate.

The water-based cleaning agent of the invention utilizes the wetting, emulsifying, permeating, dispersing, solubilizing and other actions of a fluorine-containing surfactant, an emulsifier (carboxymethyl cellulose), a penetrant (ethylene oxide propylene oxide copolymer) and the like to dissolve inorganic scaling powder, and simultaneously, gold-tin eutectic crystals and semiconductor devices are not lost.

Compared with the narrow-cut hydrocarbon cleaning agent, the hydrocarbon cleaning agent disclosed by the invention is composed of a chemical composition, is low in toxicity, low in odor and good in solubility, effectively dissolves organic components in the soldering flux, and does not lose gold-tin eutectic crystals and semiconductor devices. Wherein, the isomeric hydrocarbon has a branched chain, and the isomeric hydrocarbon has good safety and small odor; the aromatic hydrocarbon contains benzene ring and has strong dissolving power.

The main component of the resin type flux is rosin. The semi-aqueous cleaning solution effectively dissolves rosin in the resin soldering flux, and simultaneously does not lose gold-tin eutectic crystals and semiconductor devices.

Preferably, 1 liter of water-based cleaning solution comprises 30-80 g of sodium metasilicate, 10-30 g of sodium hydroxide, 20-50 g of sodium carbonate, 30-80 g of ethylene oxide propylene oxide copolymer, 3-10 g of carboxymethyl cellulose, 0-2 g of fluorine-containing surfactant, 0-5 g of complexing agent, 0-5 g of organic silicon defoaming agent and the balance of deionized water.

More preferably, 1 liter of water-based cleaning solution comprises 40-70 g of sodium metasilicate, 20-30 g of sodium hydroxide, 30-40 g of sodium carbonate, 40-60 g of ethylene oxide propylene oxide copolymer, 4-7 g of carboxymethyl cellulose, 0-2 g of fluorine-containing surfactant, 1-3 g of complexing agent, 1-3 g of organosilicon defoaming agent and the balance of deionized water.

The fluorine-containing surfactant is one or more of sodium perfluorooctanoate, potassium perfluorooctanoate and perfluorooctanoic acid; the complexing agent is one or more of sodium citrate, EDTA (ethylene diamine tetraacetic acid) disodium and EDTA tetrasodium.

The water-based cleaning solution disclosed by the invention has the advantages that the permeation and capacity increasing effects of the water-based cleaning solution are improved by adjusting the contents of the active agent, the emulsifier and the penetrant, so that the cleaning effect of the water-based cleaning solution is further improved.

In order to improve the cleaning capacity, the hydrocarbon cleaning agent also comprises copper and phosphorus, the copper and the phosphorus are added in the hydrocarbon cleaning agent, the acid is neutralized in the initial stage of dissolving the soldering flux, the hydrocarbon cleaning agent has super-strong acid resistance, and the cleaning material is ensured not to be corroded.

It should be noted that the cleaning time can be shortened by raising the temperature of the cleaning liquid, but the reliability of the semiconductor device is affected by an excessively high temperature of the cleaning liquid, and the reliability of the semiconductor device is also affected if the semiconductor device is immersed in the cleaning liquid for an excessively long time. In order to shorten the cleaning time and improve the cleaning effect and reliability, the temperature of the cleaning solution is preferably 50 +/-10 ℃, and the soaking time is preferably 1-5 min.

Preferably, the temperature of the water-based cleaning solution is 55 +/-5 ℃, and the soaking time is 1-3 min.

Preferably, the temperature of the hydrocarbon cleaning fluid is 45 +/-5 ℃, and the soaking time is 2-4 min.

Preferably, the temperature of the pure solvent cleaning solution is 50 +/-5 ℃, and the soaking time is 1-3 min.

In order to improve the fluxing capacity of the soldering flux, active substances, such as zinc chloride, ammonium chloride, organic acids and halides thereof, organic amines and halides thereof, hydrazines and halides thereof, amide urea and the like, are often added. Although the flux has high fluxing capacity, halogen ions are difficult to clean, the ion residue is high, halogen elements (mainly chloride) have strong corrosivity, and the surfactant is mainly a fatty acid group or aromatic group nonionic surfactant and has the main functions of reducing the surface tension generated when the solder is contacted with the terminal pin metal, enhancing the surface wetting force and enhancing the penetrating force of the organic acid activator.

In order to remove the substances, the three types of cleaning solutions further comprise an auxiliary agent, wherein the auxiliary agent comprises at least one of a ketone substance, an alcohol substance and an ester substance, and the ketone substance comprises at least one of acetone and toluene isobutyl ketone; the alcohol substance comprises at least one of ethanol, propanol and butanol; the ester substance comprises at least one of ethyl acetate and butyl acetate.

Preferably, the addition amount of the auxiliary agent is 1-10%.

The main function of the ketone substance, the alcohol substance and the ester substance added in the cleaning solution is to dissolve the solid components in the soldering flux to form a uniform solution, and simultaneously, the oil stain on the metal surface can be cleaned, and the corrosion of halogen elements to devices is avoided.

In addition, since foreign matters in the reflow furnace and solder resist emissions remain after gold-tin soldering of the semiconductor device and affect the quality of the semiconductor device, the cleaning solution described above is also removed to remove not only the flux but also the foreign matters in the reflow furnace and the solder resist emissions.

Secondly, soaking the semiconductor device in a water tank filled with pure water;

because the cleaning liquid is organic, organic matters or inorganic matters on the substrate of the semiconductor device can be dissolved in the cleaning process, so that conductors or insulators are generated, and the substances can cause the risk of short circuit on the substrate and influence heat dissipation. Therefore, the invention removes the cleaning liquid remaining on the semiconductor device by pure water.

In order to ensure that the pure water can be in full contact with the cleaning liquid and quickly remove the cleaning liquid remained on the semiconductor device, the water tank is provided with a water circulation system and a filter screen, the pure water in the water tank forms water circulation through the circulation system, and the filter screen is used for filtering impurities in the water tank and keeping the cleaning effect.

Referring to fig. 1, a water inlet 11 and a water outlet 12 are arranged at the bottom of the water tank 1, the water inlet 11 and the water outlet 12 are connected through a pipeline 13, a circulating pump 14 and a filter screen 15 are arranged on the pipeline 13, the circulating pump 14 pumps pure water in the water tank 1 out of the water outlet 12, and the pumped pure water enters the water tank 1 through the pipeline 13 from the water inlet 11, so that the pure water in the water tank 1 is circulated.

In order to effectively remove the cleaning liquid and ensure that the pure water can be fully contacted with the cleaning liquid, the semiconductor device is further soaked in the water tank for at least two times of water circulation cleaning, and the time of each circulation cleaning is 1-3 min.

Preferably, the flow rate of the outlet water of the pure water in the water tank is 0.5-6 m/s, and the flow rate of the inlet water is 0.5-5 m/s. If the water flow of the outlet water is more than 6m/s and the water flow of the inlet water is more than 5m/s, the water flow is too large, so that large impact force is caused to the semiconductor device, and the semiconductor device is cracked or damaged; if the water flow of the outlet water is less than 0.5m/s and the water flow of the inlet water is less than 0.5m/s, the water flow is too small to remove the residual cleaning liquid and pollutants in the gap.

Preferably, the flow rate of the outlet water of the pure water in the water tank is 1-3 m/s, and the flow rate of the inlet water is 1-3 m/s.

The cleaning time can be shortened by raising the temperature of the pure water, but the reliability of the semiconductor device is affected by an excessively high temperature of the pure water. In order to shorten the cleaning time and improve the cleaning effect and reliability, it is preferable that the temperature of the pure water is 50 ± 10 ℃.

The conductivity of the pure water is less than or equal to 2 mus/cm, and if the conductivity of the pure water is more than 2 mus/cm, the purity of the water is insufficient, and not only the residual cleaning solution cannot be removed, but also secondary pollution is caused.

And thirdly, air-drying the semiconductor device by adopting hot air to remove pure water on the semiconductor device.

Specifically, a high-speed air heater is adopted to air dry the semiconductor device, so that pure water remained on the semiconductor device is evaporated, the pure water on the semiconductor device is removed, and meanwhile, water stain remained on the semiconductor device is avoided.

According to the invention, the semiconductor device is dried by hot air, so that continuous operation can be realized, and the cleaning efficiency is improved; in addition, the hot air is adopted to air-dry the semiconductor device, and other impurities on the semiconductor device can be blown away, so that the reliability of the semiconductor device is further improved; secondly, the semiconductor device is air-dried by hot air, and the hot air with lower temperature can be adopted in the same time, so that the influence of higher heating temperature on the special semiconductor device is avoided.

Preferably, the hot air temperature is 30-120 ℃, and the air blowing time is 1-7 min.

Since the water stain usually contains minerals, metal ions and the like, there is a risk of open circuit or short circuit of the semiconductor device, and the water stain covers the surface of the semiconductor device to affect the heat dissipation effect.

The cleaning method provided by the invention adopts the cleaning agent to remove the soldering flux and other pollutants after gold-tin soldering by the mutual matching of the steps (I), (II) and (III), thereby improving the reliability of the semiconductor device; in addition, the invention adopts a hot air drying method to remove pure water of the semiconductor device, thereby avoiding residual water stain on the semiconductor device and further improving the reliability of the semiconductor device.

The invention will be further illustrated by the following specific examples