阅读说明：本技术 金属表面处理方法和塑料封装外壳的制备方法 (Metal surface treatment method and preparation method of plastic packaging shell ) 是由 李军 孟玉清 梁坤龙 赵玲 邹勇明 于 2020-12-15 设计创作，主要内容包括：本发明涉及金属表面处理技术领域,尤其涉及一种金属表面处理方法和塑料封装外壳的制备方法。该金属表面处理方法通过对金属表面除油除渣、去除氧化膜,然后进行微蚀处理,再进行覆膜,能够提高金属与塑料的结合紧密度,使二者之间达到气密效果。用该方法对半导体器件的塑料封装外壳的金属引线处理后,所得封装外壳能够完全实现“水密”,并具有优异的气密性,能够阻止外部环境中的水汽或空气泄漏进外壳内部。(The invention relates to the technical field of metal surface treatment, in particular to a metal surface treatment method and a preparation method of a plastic packaging shell. According to the metal surface treatment method, the oil and slag removal and the oxide film removal are performed on the metal surface, then the micro-etching treatment is performed, and then the film covering is performed, so that the combination tightness of metal and plastic can be improved, and the airtight effect is achieved between the metal and the plastic. After the metal lead of the plastic packaging shell of the semiconductor device is processed by the method, the obtained packaging shell can completely realize 'watertight', has excellent air tightness and can prevent water vapor or air in the external environment from leaking into the shell.)

1. A metal surface treatment method is characterized by comprising the following steps:

removing oil and slag on the surface of the metal to be treated, removing an oxidation film, and finishing pretreatment;

carrying out micro-etching treatment on the pretreated metal surface;

and (3) coating the metal surface subjected to the microetching treatment with a film forming solution, and drying, wherein the film forming solution contains the tristhiocyanic acid or the salt thereof.

2. The metal surface treatment method according to claim 1, wherein the microetching treatment is performed by: immersing the pretreated metal surface into an acidic microetching reagent, taking out after 55-65 s, and washing with water; the acid microetching reagent contains 40-60 g/L potassium ferricyanide, 80-120 g/L hydrochloric acid, 40-60 g/L nitric acid, 250-350 g/L ammonium chloride, 20-30 g/L copper chloride and 50-70 g/L sulfuric acid, and the solvent is water.

3. The metal surface treatment method according to claim 2, wherein the microetching process further comprises: and deslagging the metal surface after washing by using an alkaline aqueous solution, activating by using an acidic aqueous solution, and drying.

4. The metal surface treatment method according to claim 3, wherein the step of removing the slag with the alkaline aqueous solution comprises the following steps: and soaking the washed metal surface in a caustic soda solution with the concentration of 40-60 g/L at 25-40 ℃ for 4-6 min, and quickly washing after taking out.

5. The metal surface treatment method according to claim 3, wherein the step of activating the acidic aqueous solution comprises: soaking the metal surface subjected to deslagging by the alkaline aqueous solution in the acidic aqueous solution for 4-6 min, and quickly washing after taking out; the acidic aqueous solution contains 80-120 g/L sulfuric acid, 80-120 g/L phosphoric acid and 80-120 g/L ammonium oxalate.

6. The metal surface treatment method according to claim 1, wherein the deposition solution comprises 0.4 to 0.8mol/L trithiocyanuric acid or trisodium trithiocyanuric acid, 5 to 10g/L dimethyl sulfoxide and 5 to 10g/L film forming resin, and the solvent is 55 to 75% ethanol.

7. The metal surface treatment method according to claim 6, wherein the operation of coating with the deposition solution is: and immersing the metal surface subjected to the microetching treatment in the film forming solution at the temperature of 55-65 ℃ for 10-15 min, taking out, and washing with water within 20 s.

8. The metal surface treatment method according to claim 1, wherein the step of removing oil and slag and an oxide film comprises: soaking the metal surface to be treated in an oil removing and degreasing solution until oil stains are separated, taking out, cleaning with hot water, and immersing in a 10-30 wt% hydrochloric acid solution for 4-6 min.

9. The metal surface treatment method according to any one of claims 1 to 8, wherein the material of the metal surface is copper and a copper alloy, aluminum and an aluminum alloy, or kovar alloy.

10. The preparation method for preparing the plastic packaging shell by adopting the metal surface treatment method as claimed in any one of claims 1 to 9 specifically comprises the following steps:

carrying out surface treatment on the metal lead by using the metal surface treatment method;

and the metal lead subjected to surface treatment and the plastic master batch are subjected to co-injection molding to form a plastic ring with the metal lead, then a heat sink is bonded below the plastic ring, and a cover plate is welded above the plastic ring to form the plastic packaging shell of the airtight plastic packaging shell.

Technical Field

The invention relates to the technical field of metal surface treatment, in particular to a metal surface treatment method and a preparation method of a plastic packaging shell.

Background

The plastic package of the semiconductor device usually adopts the potting process, and the flow thereof is generally as follows: gold plating is carried out on the processed metal lead frame, a chip is welded or bonded on the metal lead frame, and alloy wires are bonded on the gold plating area of the chip and the surface of the metal lead frame for circuit interconnection; and (3) encapsulating the chip and the metal lead frame by using a glue encapsulating machine, and heating to solidify the epoxy resin so as to fill all gaps without allowing a cavity, thereby obtaining a device with a solid interior.

The metal lead, the chip and the thermosetting epoxy resin belong to different substances, the thermal expansion coefficients are different, and the change of the external temperature can cause the layering of the different substances to generate gaps, so that the function of the semiconductor device is degraded or failed. In addition, in the use process of the semiconductor device, external conditions such as vibration, environmental temperature and humidity can also cause layering among different substances.

Disclosure of Invention

In order to solve the technical problems, the invention provides a metal surface treatment method and a preparation method of a plastic packaging shell. The metal surface treatment method can improve the combination tightness of metal and plastic, so that the metal and the plastic can achieve an airtight effect. The metal lead processed by the method can be made into an airtight plastic packaging shell together with the plastic master batch, the obtained plastic packaging shell can completely realize 'watertight', has excellent airtightness, and can prevent water vapor or air in the external environment from leaking into the shell.

In order to achieve the purpose of the invention, the embodiment of the invention adopts the following technical scheme:

in a first aspect, an embodiment of the present invention provides a metal surface treatment method, which specifically includes the following steps:

removing oil and slag on the surface of the metal to be treated, removing an oxidation film, and finishing pretreatment;

carrying out micro-etching treatment on the pretreated metal surface;

and (3) coating the metal surface subjected to the microetching treatment with a film forming solution, and drying, wherein the film forming solution contains the tristhiocyanic acid or the salt thereof.

After removing oil and slag and oxide film on the surface of metal, the discontinuous natural oxide film on the surface can be removed. After the microetching treatment, a concave-convex covering surface is formed on the metal surface, and the specific surface area is increased. Finally, the film is coated in the specific film-forming solution, and an oxide film can be formed on the metal surface and the concave-convex positions. The oxide film contains thiol substances, and can simultaneously generate chemical reaction with plastics and metals, so that the plastics and the metals are firmly combined. The treatment method can be used for various situations where metal and plastic are required to be tightly combined, such as surface treatment of metal leads of a plastic packaging shell of a semiconductor device. After the metal lead is processed by the method, the bonding tightness and the air tightness of the metal lead and the plastic can be greatly improved, and the metal lead helps to prevent water vapor or air in the external environment of the packaging shell from leaking into the shell.

Preferably, the microetching treatment process is as follows: immersing the pretreated metal surface into an acidic microetching reagent, taking out after 55-65 s, and washing with water; the acid microetching reagent contains 40-60 g/L potassium ferricyanide, 80-120 g/L hydrochloric acid, 40-60 g/L nitric acid, 250-350 g/L ammonium chloride, 20-30 g/L copper chloride and 50-70 g/L sulfuric acid, and the solvent is water. Dissolving the solute components in water according to the concentration to obtain the acidic microetching reagent. The metal surface has certain active sites which are not continuous, all components of the acidic microetching reagent are matched with each other and can react with sites with certain activity values on the metal surface, the metal surface forms a concave-convex covering surface within a specific soaking time, the contact area between the metal surface and plastic is increased, certain amine substances are adsorbed, an anchor bolt structure is formed between the metal surface and the plastic, and the binding tightness is increased.

Preferably, the acidic microetching reagent contains 45-55 g/L potassium ferricyanide, 90-110 g/L hydrochloric acid, 45-55 g/L nitric acid, 280-320 g/L ammonium chloride, 22-28 g/L copper chloride and 55-65 g/L sulfuric acid.

Preferably, the acidic microetching agent contains 50g/L potassium ferricyanide, 100g/L hydrochloric acid, 50g/L nitric acid, 300g/L ammonium chloride, 25g/L copper chloride and 60g/L sulfuric acid.

Preferably, the process of the microetching treatment further comprises: and deslagging the metal surface after washing by using an alkaline aqueous solution, activating by using an acidic aqueous solution, and drying. And soaking the metal surface treated by the acidic microetching reagent in an alkaline aqueous solution to neutralize the acidic microetching reagent possibly remaining on the metal surface, and further removing the residual oxidized loose layer on the metal surface to finish deslagging treatment. The subsequent use of an acidic aqueous solution can neutralize the lye, activate the metal surface, and increase its adsorption to the amine series compounds. The activity of the sites on the metal surface, which react with the acidic microetching reagent, is further improved after the acidic microetching reagent is used for treating the sites, and then a large number of densely distributed corrosion pits can be formed on the metal surface after the alkaline aqueous solution is used for deslagging and the acidic aqueous solution is used for activating, so that the specific surface area of the metal surface is further increased, the contact area of the metal surface and the plastic is increased, and the combination tightness of the metal surface and the plastic is enhanced.

Preferably, the method for removing the slag of the alkaline aqueous solution comprises the following specific steps: and soaking the washed metal surface in a caustic soda solution with the concentration of 40-60 g/L at 25-40 ℃ for 4-6 min, and quickly washing after taking out. The concentration of the caustic soda solution may be more preferably 50 g/L. The soaking time is preferably 5 min.

Preferably, the step of activating the acidic aqueous solution comprises: soaking the metal surface subjected to deslagging by the alkaline aqueous solution in the acidic aqueous solution for 4-6 min, and quickly washing after taking out; the acidic aqueous solution contains 80-120 g/L sulfuric acid, 80-120 g/L phosphoric acid and 80-120 g/L ammonium oxalate. Further, 100g/L sulfuric acid, 100g/L phosphoric acid and 100g/L ammonium oxalate are preferably used as the solute components in the acidic aqueous solution. The soaking time is preferably 5 min.

The number of washing times after soaking in the acidic microetching reagent, the alkaline aqueous solution, and the acidic aqueous solution is preferably 2 or more to completely wash away the acidic microetching reagent, the alkaline aqueous solution, and the acidic aqueous solution.

The temperature of the acidic microetching reagent and the acidic aqueous solution is preferably 25-45 ℃.

Preferably, the film forming solution comprises 0.4-0.8 mol/L of trithiocyanuric acid or trisodium trithiocyanuric acid, 5-10 g/L of dimethyl sulfoxide and 5-10 g/L of film forming resin, and the solvent is 55-75% of ethanol. The film-forming resin may be selected from epoxy, phenolic or amine based resins. Preferably an amine based resin.

Preferably, the operation of coating with the deposition solution is: and immersing the metal surface subjected to the microetching treatment in the film forming solution at the temperature of 55-65 ℃ for 10-15 min, taking out, and washing with water within 20 s. The operation can form an oxidation film containing thiol substances with the thickness of 70-1500 nm on the metal surface subjected to microetching treatment and the microetching part thereof, and the thiol substances contained in the oxidation film can respectively react with the plastic and the metal to enable the plastic and the metal surface to be tightly combined, so that the airtight effect is achieved.

Preferably, the steps of removing oil and slag and removing an oxidation film are as follows: soaking the metal surface to be treated in an oil removing and degreasing solution until oil stains are separated, taking out the metal surface, and cleaning the metal surface by using hot water to remove the oil stains and residues on the metal surface; and immersing the metal surface subjected to oil and slag removal treatment in 10-30 wt% hydrochloric acid solution for 4-6 min to remove an oxide film on the metal surface. The oxide film differs depending on the kind of metal.

Preferably, the material of the metal surface is copper and copper alloy, aluminum and aluminum alloy or kovar alloy. After the metal surface of the materials is treated by the parameter conditions, micro pits with the diameter less than or equal to 5 mu m and the depth more than or equal to 1 mu m can be distributed on the surface of the metal surface.

Preferably, the drying mode can be air drying and drying. The drying temperature can be 75-85 ℃ and the drying time is 3-5 min. And sealing and packaging the metal surface obtained after drying treatment to prevent oxidation.

The metal surface obtained by the metal surface treatment method has a large number of nano-scale corrosion pits coated with an oxidation film, and the oxidation film contains thiol substances, and can generate double combination of nano-scale physical bonding and chemical reaction chain bonding between the metal surface and the plastic after contacting with the liquid plastic. The nanoscale physical connection means that nanoscale corrosion pits formed on the metal surface enable plastic and the metal surface to be occluded to form an anchor bolt effect, and the anchor bolt effect is shown in figure 1; the chemical reaction chain bonding refers to an oxide film formed on the surface of the metal and the surface of the nano-scale corrosion pit, and the oxide film can be used for generating chemical reaction with plastic and metal simultaneously through thiol substances contained in the oxide film so as to firmly bond the plastic and the metal surface.

In a second aspect, an embodiment of the present invention further provides a method for preparing a plastic package housing by using the metal surface treatment method, including the following steps:

carrying out surface treatment on the metal lead by using the metal surface treatment method;

and processing the metal lead subjected to surface treatment into a plastic packaging shell of the semiconductor device.

The plastic packaging shell of the semiconductor device is produced by using the metal lead treated by the method, the obtained plastic packaging shell can completely realize 'water tightness', has excellent air tightness, can prevent water vapor or air in the external environment from leaking into the shell, and can meet the air tightness requirement of devices with high reliability, such as military products, on the plastic packaging shell.

Drawings

FIG. 1 is a schematic view of the "anchor bolt effect" principle; in the figure, 1 represents a metal wire, 2 represents a nano-scale etching pit, and 3 represents an oxide film;

FIGS. 2-3 are SEM pictures of microetched metal leads in example 1 of the present invention;

fig. 4 is an SEM picture of a metal wire treated in example 1 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 is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The embodiment of the invention is based on the improvement of the airtight combination between the metal lead and the plastic in the injection molding process of the plastic packaging shell for chip packaging. The basic idea is to etch the metal lead wire to form micro-pits, and then form a chemically bonded film on the surface of the micro-pits and the metal lead wire to improve the bonding force between metal and plastic. Of course, the method for processing the metal lead can also be applied to the processing of other metal surfaces. The embodiment of the present invention is described by taking a metal lead as an example.

Example 1

This embodiment provides a method for processing a metal lead, which is made of copper. The method specifically comprises the following steps:

s1, soaking the metal lead wire to be processed in an oil removing and degreasing solution until oil stains are separated, taking out the metal lead wire, cleaning the metal lead wire for 2 times by using hot water, and immersing the metal lead wire in a 20 wt% hydrochloric acid solution for 5min to finish the pretreatment of removing oil and slag and removing copper oxide and cuprous oxide films.

S2, carrying out microetching treatment on the pretreated metal lead:

(1) and (3) immersing the pretreated metal lead into an acidic microetching reagent at 35 ℃, taking out after 60 seconds, and washing for 2 times. The acid microetching solution of this example contained 50g/L potassium ferricyanide, 100g/L hydrochloric acid, 50g/L nitric acid, 300g/L ammonium chloride, 25g/L copper chloride and 60g/L sulfuric acid, and the solvent was water.

(2) And (3) soaking the washed metal lead in a caustic soda solution with the concentration of 50g/L at 35 ℃ for 5min, taking out and quickly washing for 2 times. The caustic soda solution is used for neutralizing an acidic microetching agent which may remain on the microetching surface of the metal lead.

(3) And (3) soaking the metal lead subjected to deslagging and washing by the alkaline aqueous solution in an acidic aqueous solution at 35 ℃ for 5min, taking out and then quickly washing by water for 2 times. The acidic aqueous solution of this example contained 100g/L sulfuric acid, 100g/L phosphoric acid and 100g/L ammonium oxalate. The acidic aqueous solution is used for activating the surface of the metal lead, and amine functional groups are adsorbed on the micro-pits and the surface of the metal lead, so that the subsequent chemical bonding of a film forming solution is facilitated.

The metal lead subjected to the microetching treatment is observed under an electron microscope, the appearance of the metal lead is shown in figures 2 and 3, a large number of dense corrosion pits are formed on the surface of the metal lead, and the diameter of the corrosion pits is estimated to be not more than 4 mu m from the figures.

S3, coating the metal lead wire subjected to the micro-etching treatment by using the film forming solution: immersing the metal lead subjected to the microetching treatment in a film forming solution at 60 ℃ for 15min, taking out and washing with water within 20 s; the film forming solution comprises 0.6mol/L of trithiocyanuric acid, 7.5g/L of dimethyl sulfoxide and 7.5g/L of film forming resin, and the solvent is 65% ethanol.

S4, drying: air-showering for 2 min by using a dehydrator, drying at 80 +/-5 ℃, and then cooling to room temperature at normal temperature.

When the metal wire obtained by the above-described treatment method is observed under an electron microscope, as shown in fig. 4, the corrosion pits on the surface of the metal wire are covered with the newly formed film, but the morphology of the corrosion pits is not substantially affected.

Example 2

This embodiment provides a method for processing a metal lead, where the metal lead is made of copper-zinc alloy. The method specifically comprises the following steps:

s1, soaking the metal lead wire to be processed in an oil removing and degreasing solution until oil stains are separated, taking out the metal lead wire, cleaning the metal lead wire for 2 times by using hot water, and immersing the metal lead wire in a 15 wt% hydrochloric acid solution for 5.5min to finish the pretreatment of removing oil and slag and removing copper oxide, cuprous oxide and zinc oxide films.

S2, carrying out microetching treatment on the pretreated metal lead:

(1) immersing the pretreated metal lead into an acidic microetching reagent at 40 ℃, taking out after 63s, and washing for 2 times; the acid microetching solution of this example contained 45g/L potassium ferricyanide, 90g/L hydrochloric acid, 45g/L nitric acid, 280/L ammonium chloride, 22g/L copper chloride and 55g/L sulfuric acid, and the solvent was water.

(2) And soaking the washed metal lead in a caustic soda solution with the concentration of 45g/L at 40 ℃ for 5.5min, taking out and quickly washing for 2 times.

(3) Soaking the metal lead subjected to deslagging and washing in the alkaline aqueous solution in the acidic aqueous solution at 40 ℃ for 5.5min, taking out and then quickly washing for 2 times; the acidic aqueous solution of this example contained 90g/L sulfuric acid, 90g/L phosphoric acid and 90g/L ammonium oxalate.

Observing the metal lead subjected to the micro-etching treatment under an electron microscope, and forming a large number of dense corrosion pits on the surface of the metal lead.

S3, coating the metal lead wire subjected to the micro-etching treatment by using the film forming solution: immersing the metal lead subjected to the microetching treatment in a film forming solution at 60 ℃ for 15min, taking out and washing with water within 20 s; the film forming solution comprises 0.5mol/L trisodium trithiocyanate, 8g/L dimethyl sulfoxide and 8g/L film forming resin, and the solvent is 70% ethanol.

S4, drying: air-showering for 2 min by using a dehydrator, drying at 80 +/-5 ℃, and then cooling to room temperature at normal temperature. The metal lead obtained by the above treatment method is observed under an electron microscope, and the corrosion pits on the surface of the metal lead are covered by the newly formed film.

Example 3

The embodiment provides a metal lead processing method, wherein the metal lead is made of copper-aluminum alloy. The method specifically comprises the following steps:

s1, soaking the metal lead wire to be processed in an oil removing and degreasing solution until oil stains are separated, taking out the metal lead wire, cleaning the metal lead wire for 2 times by using hot water, and immersing the metal lead wire in 25 wt% hydrochloric acid solution for 4.5min to finish the pretreatment of removing oil and slag and removing an aluminum oxide film.

S2, carrying out microetching treatment on the pretreated metal lead:

(1) immersing the pretreated metal lead into an acidic microetching reagent at 30 ℃, taking out after 57 seconds, and washing for 2 times; the acid microetching solution of this example contained 55g/L potassium ferricyanide, 110g/L hydrochloric acid, 55g/L nitric acid, 320g/L ammonium chloride, 28g/L copper chloride and 65g/L sulfuric acid, and the solvent was water.

(2) And soaking the washed metal lead in a caustic soda solution with the concentration of 55g/L at 30 ℃ for 4.5min, taking out and quickly washing for 2 times.

(3) Soaking the metal lead subjected to deslagging and washing in the alkaline aqueous solution in the acidic aqueous solution at 30 ℃ for 5.5min, taking out and then quickly washing for 2 times; the acidic aqueous solution of this example contained 110g/L sulfuric acid, 110g/L phosphoric acid and 110g/L ammonium oxalate.

Observing the metal lead subjected to the micro-etching treatment under an electron microscope, and forming a large number of dense corrosion pits on the surface of the metal lead.

S3, coating the metal lead wire subjected to the micro-etching treatment by using the film forming solution: immersing the metal lead subjected to the microetching treatment in a film forming solution at 60 ℃ for 15min, taking out and washing with water within 20 s; the film forming solution comprises 0.7mol/L of trithiocyanuric acid, 6g/L of dimethyl sulfoxide and 6g/L of film forming resin, and the solvent is 60% ethanol.

S4, drying: air-showering for 2 min by using a dehydrator, drying at 80 +/-5 ℃, and then cooling to room temperature at normal temperature. The metal lead obtained by the above treatment method is observed under an electron microscope, and the corrosion pits on the surface of the metal lead are covered by the newly formed film.

Example 4

This example provides a method for processing a metal lead, where the metal lead is made of aluminum-silicon alloy. The method specifically comprises the following steps:

s1, soaking the metal lead wire to be processed in an oil removing and degreasing solution until oil stains are separated, taking out the metal lead wire, cleaning the metal lead wire for 2 times by using hot water, and immersing the metal lead wire in a 10 wt% hydrochloric acid solution for 6min to finish the pretreatment of removing oil and slag and removing an aluminum oxide film.

S2, carrying out microetching treatment on the pretreated metal lead:

(1) and (3) immersing the pretreated metal lead into an acidic microetching reagent at 45 ℃, taking out after 65 seconds, and washing for 2 times. The acid microetching solution of this example contained 40g/L potassium ferricyanide, 80g/L hydrochloric acid, 40g/L nitric acid, 250g/L ammonium chloride, 20g/L copper chloride and 50g/L sulfuric acid, and the solvent was water.

(2) And soaking the washed metal lead in 40 ℃ caustic soda solution with the concentration of 40g/L for 6min, taking out and quickly washing for 2 times.

(3) And (3) soaking the metal lead subjected to deslagging and washing by the alkaline aqueous solution in the 45 ℃ acidic aqueous solution for 4min, taking out and then quickly washing for 2 times. The acidic aqueous solution of this example contained 80g/L sulfuric acid, 80g/L phosphoric acid and 80g/L ammonium oxalate.

Observing the metal lead subjected to the micro-etching treatment under an electron microscope, and forming a large number of dense corrosion pits on the surface of the metal lead.

S3, coating the metal lead wire subjected to the micro-etching treatment by using the film forming solution: immersing the metal lead subjected to the microetching treatment in a film forming solution at 55 ℃ for 15min, taking out and washing with water within 20 s; the film forming solution comprises 0.4mol/L trisodium trithiocyanate, 5g/L dimethyl sulfoxide and 5g/L film forming resin, and the solvent is 55% ethanol.

S4, drying: air-showering for 2 min by using a dehydrator, drying at 80 +/-5 ℃, and then cooling to room temperature at normal temperature. The metal lead obtained by the above treatment method is observed under an electron microscope, and the corrosion pits on the surface of the metal lead are covered by the newly formed film.

Example 5

This embodiment provides a method for processing a metal lead, which is made of kovar alloy. The method specifically comprises the following steps:

s1, soaking the metal lead wire to be processed in an oil removing and degreasing solution until oil stains are separated, taking out the metal lead wire, cleaning the metal lead wire for 2 times by using hot water, and immersing the metal lead wire in a 30 wt% hydrochloric acid solution for 4min to finish the pretreatment of removing oil and slag and removing iron oxide, ferrous oxide, cobalt oxide, nickel oxide and nickelous oxide films.

S2, carrying out microetching treatment on the pretreated metal lead:

(1) and (3) immersing the pretreated metal lead into an acidic microetching reagent at 25 ℃, taking out after 55s, and washing for 2 times. The acid microetching solution of this example contained 60g/L potassium ferricyanide, 120g/L hydrochloric acid, 60g/L nitric acid, 350g/L ammonium chloride, 30g/L copper chloride and 70g/L sulfuric acid, and the solvent was water.

(2) And soaking the washed metal lead in a caustic soda solution with the concentration of 60g/L at 25 ℃ for 4min, taking out and quickly washing for 2 times.

(3) And (3) soaking the metal lead subjected to deslagging and washing by the alkaline aqueous solution in an acidic aqueous solution at 25 ℃ for 6min, taking out and then quickly washing for 2 times. The acidic aqueous solution of this example contained 120g/L sulfuric acid, 120g/L phosphoric acid and 120g/L ammonium oxalate.

Observing the metal lead subjected to the micro-etching treatment under an electron microscope, and forming a large number of dense corrosion pits on the surface of the metal lead.

S3, coating the metal lead wire subjected to the micro-etching treatment by using the film forming solution: immersing the metal lead subjected to the microetching treatment in a film forming solution at 65 ℃ for 10min, taking out and washing with water within 20 s; the film forming solution comprises 0.8mol/L trisodium trithiocyanate, 10g/L dimethyl sulfoxide and 10g/L film forming resin, and the solvent is 75% ethanol.

S4, drying: air-showering for 2 min by using a dehydrator, drying at 80 +/-5 ℃, and then cooling to room temperature at normal temperature. The metal lead obtained by the above treatment method is observed under an electron microscope, and the corrosion pits on the surface of the metal lead are covered by the newly formed film.

Example 6

The embodiment provides a method for preparing a plastic packaging shell, which specifically comprises the following steps:

the metal lead wire is subjected to surface treatment by the treatment method of the metal lead wire in the embodiment 1;

and (3) performing co-injection molding on the metal lead subjected to surface treatment and the plastic master batch to form a plastic ring with the metal lead, then bonding a heat sink below the plastic ring, and welding a cover plate above the plastic ring to form the airtight plastic packaging shell. The resultant plastic package was tested for hermetic seal according to method 1014 of GJB548, condition a4, using helium leak detection. The detection shows that the leakage rate is less than or equal to 1 x 10^-8Pa·m³/s(He)。

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.