A process for electroless plating gold on a beryllium copper alloy surface

Abstract

The application discloses a kind of beryllium copper alloy surface gold plating chemical plating process, comprising the following steps: S1, cleaning;S2, preparation of gold salt: take pure gold raw material is placed in beaker, after adding concentrated hydrochloric acid, concentrated nitric acid is concentrated and obtained orange yellow chloroauric acid crystal;Chloroauric acid crystal is dissolved in ultrapure water and dissolved to obtain chloroauric acid solution;KI solution is added to obtain AuI3 precipitate;Filtering and separating object and decomposing obtain AuI solid;Add thiourea (Tu) solution to dissolve AuI solid, obtain transparent auric compound solution;Concentrate, cool to obtain gold salt, and store after filtration, drying is ready for use;S3, preparation of gold plating solution;S4, gold plating.The application adopts the method of chemical plating to be plated with gold on the surface of beryllium copper alloy, and the bonding strength is high, so as to play the role of corrosion prevention, oxidation prevention.Gold salt prepared by the application has low chemical activity, and the gold plating layer has low resistivity, good conductivity, easy to weld, good ductility and other advantages.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of beryllium copper surface treatment, and particularly relates to a chemical plating process for gold plating on a beryllium copper alloy surface. BACKGROUND

[0002] Beryllium copper alloy is a non-ferrous alloy elastic material with excellent comprehensive performance, and is called "the king of elasticity". The beryllium copper alloy has excellent performances such as high strength, high hardness, corrosion resistance, high electrical conductivity, high thermal conductivity, fatigue resistance, corrosion resistance, small elastic hysteresis, no magnetism, no spark generation during impact and the like. However, an oxide film is generated on the surface of a heat-treated beryllium copper part. The surface oxide is a mixture of beryllium oxide (BeO) and several copper oxides. The composition and thickness of the thin film depend on the temperature and the furnace atmosphere. Beryllium has a great affinity for oxygen. Since beryllium oxide cannot be reduced by hydrogen, there is no suitable heat treatment atmosphere and process to eliminate the surface beryllium oxide. During long-term use, the beryllium copper surface will also rust, and the generated copper green will increase the resistance, thereby affecting the stability of the beryllium copper alloy.

[0003] Therefore, a chemical plating process for gold plating on a beryllium copper alloy surface is urgently needed. SUMMARY

[0004] To solve the defects in the prior art, the application provides a chemical plating process for gold plating on a beryllium copper alloy surface.

[0005] To solve the above technical problems, the application provides the following technical solutions:

[0006] The application provides a chemical plating process for gold plating on a beryllium copper alloy surface, which comprises the following steps:

[0007] S1, cleaning: ultrasonic cleaning of the beryllium copper alloy part, drying and standby;

[0008] S2, preparation of gold salt, comprising the following steps:

[0009] S21, the pure gold raw material is placed in a beaker, concentrated hydrochloric acid and concentrated nitric acid are added, and then heated and evaporated in a water bath kettle. Distilled water is added to the solution multiple times during the process until the pH value is neutral. Then the solution is further concentrated to 1 / 5 of the original volume, cooled, and orange chloroauric acid crystals are obtained for standby;

[0010] S22, the chloroauric acid crystals are dissolved in ultrapure water and placed on a magnetic stirrer to obtain a chloroauric acid solution. KI solution is added according to a molar ratio of n(Au 3+ ):n(I - ) is 1:3, stirred and then placed to obtain AuI3 precipitate. AuI3 is unstable and decomposes into iodine and AuI. The precipitate is separated from the solution, and ethanol is used to filter and remove residual iodine and dry to obtain AuI solid;

[0011] S23, the obtained AuI solid is placed in a beaker, and thiourea (Tu) solution is added dropwise to dissolve the AuI solid at a molar ratio of n(Au):n(Tu) of 1:3 until the solid dissolves and disappears, and a transparent aurous complex solution is obtained after stirring;

[0012] S24, the transparent aurous complex solution is left to stand for 3 hours, concentrated by a rotary evaporator at a concentration ratio of 3:1, and then the obtained concentrated solution is cooled and crystallized in a refrigerator to obtain a gold salt, and the gold salt is stored for use after filtration and drying; wherein the gold salt is an aurous complex crystal, namely [Au(Tu)2]I;

[0013] S3, preparing a gold plating solution: the components of the gold plating solution are as follows: gold salt 1-4 g / L, complexing agent 10-15 g / L, reducing agent 2.5-6 g / L, stabilizing agent 25-40 mL / L, and buffer 5-15 g / L;

[0014] S4, gold plating: the prepared gold plating solution is placed in a water bath, and then the beryllium copper alloy part to be plated is suspended in the gold plating solution to be completely immersed, after the gold plating is completed, the beryllium copper alloy part is rinsed, dried, and inspected.

[0015] Preferably, in the step S1, the beryllium copper alloy part is ultrasonically cleaned with deionized water and alcohol respectively.

[0016] Preferably, in the step S21, the heating temperature of the water bath is 70-75°C, the volume ratio of concentrated hydrochloric acid to concentrated nitric acid is 3:1, and the cooling temperature is 3-5°C.

[0017] Preferably, in the step S21, the chloroauric acid crystal is dried in a desiccator containing concentrated sulfuric acid and then stored in a desiccator containing silica gel for standby use.

[0018] Preferably, in the step S24, the temperature of the rotary evaporator is 42-45°C.

[0019] Preferably, in the step S24, the cooling temperature of the concentrated solution is 2-4°C, and the cooling time is 12-24 hours.

[0020] Preferably, in the step S22, the concentration of the KI solution is 20-30 mg / mL, and in the step S23, the concentration of the thiourea solution is 20-50 mg / mL.

[0021] Preferably, the complexing agent is at least one of thiourea and lactic acid, the reducing agent is at least one of thiourea and dimethylamine borane, the stabilizing agent is at least one of ethylenediaminetetraacetic acid and hydroxyethylidene diphosphonic acid, and the buffer is at least one of citric acid and Na2HPO4.

[0022] Preferably, the temperature of the water bath in the step S4 is 30-70 DEG C, the gold plating time is 5-40 min, and the pH value is 2-8.

[0023] Compared with the prior art, the application has the following beneficial effects:

[0024] The application adopts the method of chemical plating to plate gold on the surface of beryllium copper alloy, and has high bonding strength, thereby playing the roles of corrosion prevention and oxidation prevention, and is widely applied to precision instruments, integrated circuits, circuit boards and the like. The gold salt prepared by the application has low chemical activity, fast gold deposition rate, good stability, and can obtain a smooth, bright and dense gold plating layer, and the gold plating layer has the advantages of low resistivity, good conductivity, easy welding, good ductility and the like. Embodiment

[0025] The preferred embodiments of the application are described below, and it should be understood that the preferred embodiments described herein are only used for description and explanation of the application, and are not used to limit the application. Embodiment

[0026] The chemical plating process for plating gold on the surface of beryllium copper alloy includes the following steps:

[0027] S1, cleaning: the beryllium copper alloy parts are respectively cleaned with deionized water and alcohol by ultrasonic cleaning, and are dried for standby;

[0028] S2, preparation of gold salt, including the following steps:

[0029] S21, the pure gold raw material is placed in a beaker, concentrated hydrochloric acid and concentrated nitric acid with a volume ratio of 3:1 are added, and then the solution is heated to 75 DEG C in a water bath to evaporate and concentrate, and distilled water is added to the solution several times during the process until the pH value is neutral; then the solution is continuously concentrated to 1 / 5 of the original volume, and is cooled at 5 DEG C to obtain orange yellow chloroauric acid crystals, which are dried in a desiccator containing concentrated sulfuric acid and stored in a desiccator containing silica gel for standby;

[0030] S22, the chloroauric acid crystals are dissolved in ultrapure water and placed on a magnetic stirrer to dissolve to obtain a chloroauric acid solution; KI solution with a concentration of 30 mg / mL is added according to a molar ratio of n(Au 3+ ):n(I - ) is 1:3, and after stirring, the AuI3 precipitate is obtained by standing; AuI3 is unstable and decomposes into iodine and AuI, then the precipitate is separated from the solution, and the residual iodine is removed by filtration with ethanol and dried to obtain AuI solid;

[0031] S23, the obtained AuI solid is placed in a beaker, and a thiourea (Tu) solution with a concentration of 50 mg / mL is added dropwise to dissolve the AuI solid at a molar ratio of n(Au):n(Tu) of 1:3 until the solid disappears, and a transparent aurous complex solution is obtained after stirring;

[0032] S24, the transparent aurous complex solution is left to stand for 3 hours, concentrated by a rotary evaporator at a concentration ratio of 3:1, and then the obtained concentrated solution is placed in a refrigerator to cool and crystallize to obtain a gold salt, and the gold salt is stored for use after filtration and drying; wherein the gold salt is an aurous complex crystal, namely [Au(Tu)2]I; the temperature of the rotary evaporator is 45°C; the cooling temperature of the concentrated solution is 4°C, and the cooling time is 12 hours;

[0033] S3, a gold plating solution is prepared: the components of the gold plating solution are as follows: gold salt 4 g / L, complexing agent 15 g / L, reducing agent 2.5 g / L, stabilizing agent 25 mL / L, and buffer 5 g / L; the complexing agent is thiourea and lactic acid, the reducing agent is thiourea and dimethylamine borane, the stabilizing agent is ethylenediaminetetraacetic acid and hydroxyethylidene diphosphoric acid, and the buffer is citric acid and Na2HPO4;

[0034] S4, gold plating: the prepared gold plating solution is placed in a water bath, heated to 70°C, then the beryllium-copper alloy piece to be plated is suspended in the gold plating solution for complete immersion, and finally the pH value of the gold plating solution is monitored using a pH meter. After 10 minutes of gold plating, the beryllium-copper alloy piece is rinsed, dried, and inspected.

[0035] The plating time is 10 minutes, and the gold plating layer has poor gloss and uniformity. Example

[0036] In this embodiment, the rest is the same as Example 1, except that:

[0037] S4, gold plating: the prepared gold plating solution is placed in a water bath, heated to 70°C, then the beryllium-copper alloy piece to be plated is suspended in the gold plating solution for complete immersion, and finally the pH value of the gold plating solution is monitored using a pH meter. After 20 minutes of gold plating, the beryllium-copper alloy piece is rinsed, dried, and inspected.

[0038] The plating time is 20 minutes, and the gold plating layer has good gloss, uniformity, and adhesion. Example

[0039] In this embodiment, the rest is the same as Example 1, except that:

[0040] S4, gold plating: the prepared gold plating solution is placed in a water bath and heated to 70°C, then the beryllium copper alloy part to be plated is suspended in the gold plating solution for complete immersion, finally the pH value of the gold plating solution is monitored using a pH meter. After 30 min of gold plating, the beryllium copper alloy part is rinsed, dried and inspected.

[0041] The plating time is 30 min, and the gold plating layer has good gloss, uniformity and adhesion. Example

[0042] In this example, the rest is the same as Example 1, except that:

[0043] S4, gold plating: the prepared gold plating solution is placed in a water bath and heated to 70°C, then the beryllium copper alloy part to be plated is suspended in the gold plating solution for complete immersion, finally the pH value of the gold plating solution is monitored using a pH meter. After 40 min of gold plating, the beryllium copper alloy part is rinsed, dried and inspected.

[0044] The plating time is 40 min, and the gold plating layer has good gloss, uniformity and adhesion.

[0045] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A process for electroless plating of a gold layer on a beryllium copper alloy surface, characterized in that, The method comprises the following steps: S1, cleaning: ultrasonic cleaning of beryllium copper alloy parts, drying and standby; S2, preparation of gold salt, comprising the following steps: S21, take pure gold raw material in beaker, add concentrated hydrochloric acid, concentrated nitric acid, then evaporate and concentrate in water bath kettle, add distilled water to the solution several times during the process until the pH value is neutral; then continue to concentrate the solution to 1 / 5 of the original volume, cool, get orange chloroauric acid crystal for standby; S22, dissolve chloroauric acid crystal in ultrapure water, place on a magnetic stirrer to dissolve to obtain a chloroauric acid solution; add KI solution according to a molar ratio n(Au 3+ ):n(I - ) of 1:3 to react, stir and then stand to obtain AuI3 precipitate; AuI3 is unstable and decomposes into iodine element and AuI, then filter the precipitate and the solution to separate, further filter with ethanol to remove residual iodine element and dry to obtain AuI solid; S23, the obtained AuI solid is placed in a beaker, and thiourea (Tu) solution is added dropwise according to the molar ratio n(Au):n(Tu) 1:3 to dissolve AuI solid until the solid disappears, and then the transparent auric complex solution is obtained after stirring; S24, the transparent auric complex solution is placed in a refrigerator for 3 hours, and then concentrated by rotary evaporator according to the concentration ratio of 3:1, and then the concentrated solution is cooled and crystallized in the refrigerator to obtain gold salt, which is filtered, dried and stored for standby; wherein the gold salt is auric complex crystal, namely [Au(Tu)2]I; S3, preparation of gold plating solution: the gold plating solution is prepared as follows: gold salt 1~4 g / L, complexing agent 10~15 g / L, reducing agent 2.5~6 g / L, stabilizer 25~40 mL / L and buffer 5~15 g / L; S4, gold plating: the prepared gold plating solution is placed in a water bath kettle, and then the beryllium copper alloy parts to be plated are suspended in the gold plating solution for complete immersion, after the gold plating is completed, the beryllium copper alloy parts are rinsed, dried and inspected.

2. The electroless plating process for gold plating a beryllium copper alloy surface according to claim 1, characterized in that, In the step S1, the beryllium copper alloy parts are ultrasonically cleaned with deionized water and alcohol respectively.

3. The electroless plating process for gold plating a beryllium copper alloy surface according to claim 1, characterized by, In the step S21, the water bath kettle is heated to a temperature of 70~75℃, the volume ratio of concentrated hydrochloric acid to concentrated nitric acid is 3:1, and the cooling temperature is 3~5℃.

4. The electroless plating process for gold plating a beryllium copper alloy surface according to claim 1, characterized by, In the step S21, the chloroauric acid crystal is placed in a dryer containing concentrated sulfuric acid and stored in a dryer containing silica gel for standby.

5. The electroless plating process for gold plating a beryllium copper alloy surface according to claim 1, characterized by, In the step S24, the temperature of the rotary evaporator is 42~45℃.

6. The electroless plating process for gold plating a beryllium copper alloy surface according to claim 1, characterized by, In the step S24, the cooling temperature of the concentrated solution is 2~4℃, and the cooling time is 12~24 hours.

7. The electroless plating process for gold plating a beryllium copper alloy surface according to claim 1, characterized by, In the step S22, the concentration of KI solution is 20~30 mg / mL, and in the step S23, the concentration of thiourea solution is 20~50 mg / mL.

8. The electroless plating process for gold plating a beryllium copper alloy surface according to claim 1, characterized by, The complexing agent is at least one of thiourea and lactic acid, the reducing agent is at least one of thiourea and dimethylamine borane, the stabilizer is at least one of ethylenediaminetetraacetic acid and hydroxyethylidene diphosphoric acid, and the buffer is at least one of citric acid and Na2HPO4.

9. The electroless plating process for gold plating a beryllium copper alloy surface according to claim 1, characterized by, In the step S4, the temperature of the water bath kettle is 30~70℃, the gold plating time is 5~40 min, and the pH value is 2~8.