Silver immersion method for circuit board

Abstract

The invention discloses a silver immersion method for a circuit board, and belongs to the technical field of surface treatment. The method comprises a silver immersion liquid formula and a blending operation method, and solves the technical problems of the circuit board silver immersion liquid formula and the blending operation method. In order to improve the conductivity of the circuit board, silver plating treatment is needed. However, after a copper-clad plate is made into a circuit board, silver plating can be carried out only when all circuits are connected and then connected to a cathode during silver plating of a copper-clad circuit part, so that the operation is complex and complicated. In addition, an insulating material on the copper-clad plate is easy to separate out unknown substances under the action of current during silver plating treatment, so that the performance of a plating solution is influenced.

Description

Technical Field

[0001] The invention discloses a method for silvering a circuit board, and belongs to the technical field of surface treatment. Background Art

[0002] At present, some circuit boards need to be silver-plated to improve their conductivity. Because the circuit part is made of copper-clad materials that are conductive, and the copper-clad board is an insulating material that is not conductive, and the circuit part is composed of multiple disconnected copper-clad patterns, the circuit part needs to be silver-plated. Therefore, when the copper-clad board is made into a circuit board, the copper-clad circuit part must be silver-plated after connecting each circuit and connecting it to the cathode. The operation is complicated and tedious. In addition, when the insulating material on the copper-clad board is silver-plated, it is easy to precipitate unknown substances under the action of current, which affects the performance of the plating solution. Summary of the invention

[0003] The objects of the present invention are:

[0004] In order to solve the problem of circuit board silver immersion solution formula and mixing operation method, a circuit board silver immersion method was designed.

[0005] The technical scheme of the invention is: a method for silvering a circuit board, wherein a qualified circuit board is firstly washed with aviation gasoline for 2-3 times, and then the surface of the circuit board is evenly scrubbed with a clean wet brush dipped in decontamination powder and Vienna lime, and after being scrubbed clean, the decontamination powder and Vienna lime are washed off with running cold water, and then the oxide film on the surface of the copper-clad film of the circuit board is brushed off with a clean wet soft copper wire brush, the cleaned circuit board is put into a clean hanging basket, immersed in silver immersion liquid, immersed at a temperature of 20-40 DEG C for 3-5 minutes while shaking continuously, and after being taken out of the tank, the silver immersion liquid is washed off with two streams of clean water, and then washed with hot water of 50-60 DEG C, blown dry with compressed air, and then put into an oven for stable treatment, baked at 90-100 DEG C for 2-3 hours, and then cooled naturally.

[0006] The silver leaching solution contains 35-55 g / L of silver nitrate and 30-50 g / L of potassium cyanide.

[0007] The silver leaching solution preparation method comprises the following steps: weighing two portions of silver nitrate in proportion, with the first portion and the second portion in a ratio of 4:5 for standby use; then taking two portions of potassium cyanide, with the first portion and the second portion in a ratio of 1:3 for standby use; taking distilled water in a beaker, heating it to 30-40° C., adding the first portion of silver nitrate and potassium cyanide respectively while stirring, and when the liquid temperature drops to 20° C., adding the second portion of silver nitrate and potassium cyanide respectively while stirring, and the solution can be used after being left to stand for 2-3 hours.

[0008] The aviation gasoline is No. 150 or No. 180 aviation gasoline with a pH value of 5-6. 2. The method for silvering a circuit board according to claim 1, characterized in that the ratio of the decontamination powder to Vienna lime is 3:1

[0009] The purity of the silver nitrate and potassium cyanide is industrial grade.

[0010] The soft copper wire brush should be softened. First wash it with No. 150 or No. 180 aviation gasoline, then wash it with metal detergent solution at 45℃ for 5 minutes, then wash it with 60℃ hot water for 20S, then wash it with cold water for 20S until the oil stains on the copper wire brush surface are removed, then use copper pickling solution to remove the oxides on the copper wire brush surface, wash it with water, blow it dry, put it in an oven to bake at 180-190℃ for 2-3 hours, cool it naturally in the oven and set it aside.

[0011] The hanging basket is made of ethylene or polyethylene.

[0012] The Vienna lime is medical sodium lime.

[0013] The brush is a pig bristle sx-5510 with a specification of 63mm.

[0014] The beneficial effects of the present invention are:

[0015] (1) The immersion silver method does not require electrical treatment, it is only a chemical silver plating method.

[0016] (2) The silver immersion solution has simple composition and good stability.

[0017] (3) The silver immersion process is simple, easy to operate and has low pollution.

[0018] (4) The silver immersion method breaks the traditional alkaline washing and acid washing process, and adopts the gasoline washing-decontamination powder and Vienna lime scrubbing-brushing (copper brush) process, which has less pollution to the bath liquid and is more environmentally friendly.

[0019] (5) The conventional method for improving the conductivity of the circuit board is electroplating silver. The present invention creatively adopts the silver immersion method, which avoids the insulation material on the circuit board from easily precipitating unknown substances under the action of current during electroplating silver, thereby contaminating the plating solution. At the same time, it eliminates the complicated operation of connecting each circuit to the cathode before silver plating. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the embodiments:

[0021] Acceptance - gasoline washing - scrubbing with decontamination powder and Vienna lime - brushing - hanging - silver impregnation - stabilization treatment - inspection - packaging

[0022] New process description

[0023] For qualified circuit boards, first wash them 2-3 times with 150 or 180 aviation gasoline with a PH value of 5-6, then use a clean wet brush dipped in decontamination powder and Vienna lime to evenly scrub the surface of the circuit board. After scrubbing, use running cold water to wash off the decontamination powder and Vienna lime to remove the oil and other coverings on the surface of the circuit board. Then use a clean and wet soft copper wire brush to brush off the oxide film on the surface of the copper film. Put the cleaned circuit board into a clean hanging basket, immerse it in silver at a temperature of 20-40℃ for 3-5 minutes while shaking continuously to ensure that the copper film on the circuit board is evenly silvered. After leaving the tank, wash the silver immersion liquid with two streams of clean water, then wash it with 50-60℃ hot water, blow it dry with compressed air, and then put it in the oven for stable treatment, bake it at 90-100℃ for 2-3 hours and cool it naturally. The silver film covering the surface of the circuit is uniform and complete, with strong bonding, and the color of the silver film is silvery white to grayish white.

[0024] (1) Silver immersion solution composition

[0025]

[0026] (2) Silver immersion solution preparation method:

[0027] Taking the preparation of 1 liter of silver immersion solution as an example, first take 20 grams and 25 grams of silver nitrate and set aside, then take 10 grams and 30 grams of potassium cyanide and set aside, use a beaker to take 1 liter of distilled water, heat it to 25°C, add 20 grams of silver nitrate and 10 grams of potassium cyanide respectively while stirring, wait until the liquid temperature drops to 20°C, add 25 grams of silver nitrate and 30 grams of potassium cyanide respectively while stirring, and let it stand for 3 hours before use.

[0028] (3) Precautions for preparing and using silver immersion solution:

[0029] (a.) When preparing, add the drugs in strict order and stir the solution continuously while adding the drugs.

[0030] (b.) The prepared silver-immersion solution can be stored for half a month. It is strictly forbidden to prepare and reuse the silver-immersion solution that has expired. It is best to use as much silver-immersion solution as possible.

[0031] Implementation Case 1

[0032] A method for silvering a circuit board. A qualified circuit board is first washed twice with aviation gasoline, then the surface of the circuit board is evenly scrubbed with a clean wet brush dipped in decontamination powder and Vienna lime, after being scrubbed clean, the decontamination powder and Vienna lime are washed off with running cold water, and then the oxide film on the surface of the copper film of the circuit board is brushed off with a clean wet soft copper wire brush, the cleaned circuit board is put into a clean hanging basket, immersed in silver immersion liquid, immersed at 20 DEG C for 3 minutes while shaking continuously, and after being taken out of the tank, the silver immersion liquid is washed off with two streams of clean water, then washed with 50 DEG C hot water, blown dry with compressed air, and then put into an oven for stable treatment, baked at 90 DEG C for 3 hours, and cooled naturally.

[0033] The silver leaching solution contains 35 g / L silver nitrate and 30 g / L potassium cyanide.

[0034] The silver leaching solution preparation method comprises the following steps: weighing two portions of silver nitrate in proportion, with the first portion and the second portion in a ratio of 4:5 for standby use; then taking two portions of potassium cyanide, with the first portion and the second portion in a ratio of 1:3 for standby use; taking distilled water in a beaker, heating it to 30° C., adding the first portion of silver nitrate and potassium cyanide respectively while stirring, and when the liquid temperature drops to 20° C., adding the second portion of silver nitrate and potassium cyanide respectively while stirring, and the solution can be used after being left to stand for 2 hours.

[0035] Implementation Case 2

[0036] A method for silvering a circuit board. A qualified circuit board is first washed with aviation gasoline for three times, then the surface of the circuit board is evenly scrubbed with a clean wet brush dipped in decontamination powder and Vienna lime, after being scrubbed clean, the decontamination powder and Vienna lime are washed off with running cold water, and then the oxide film on the surface of the copper film of the circuit board is brushed off with a clean wet soft copper wire brush, the cleaned circuit board is put into a clean hanging basket, immersed in silver immersion liquid, immersed at 30 DEG C for 3 minutes while shaking continuously, washed with two streams of clean water after being taken out of the tank, then washed with 50 DEG C hot water, blown dry with compressed air, and then put into an oven for stable treatment, baked at 100 DEG C for 2 hours, and cooled naturally.

[0037] The silver leaching solution contains 35 g / L silver nitrate and 30 g / L potassium cyanide.

[0038] The silver leaching solution preparation method comprises the following steps: weighing two portions of silver nitrate in proportion, with the first portion and the second portion in a ratio of 4:5 for standby use; then taking two portions of potassium cyanide, with the first portion and the second portion in a ratio of 1:3 for standby use; taking distilled water in a beaker, heating it to 30° C., adding the first portion of silver nitrate and potassium cyanide respectively while stirring, and when the liquid temperature drops to 20° C., adding the second portion of silver nitrate and potassium cyanide respectively while stirring, and the solution can be used after being left to stand for 2-3 hours.

[0039] Implementation Case 3

[0040] A method for silvering a circuit board. A qualified circuit board is first washed with aviation gasoline for three times, then the surface of the circuit board is evenly scrubbed with a clean wet brush dipped in decontamination powder and Vienna lime, after being scrubbed clean, the decontamination powder and Vienna lime are washed off with running cold water, and then the oxide film on the surface of the copper film of the circuit board is brushed off with a clean wet soft copper wire brush, the cleaned circuit board is put into a clean hanging basket, immersed in silver immersion liquid, immersed at a temperature of 20 DEG C for 5 minutes while shaking continuously, and after being taken out of the tank, the silver immersion liquid is washed off with two streams of clean water, then washed with 50 DEG C hot water, blown dry with compressed air, and then put into an oven for stable treatment, baked at 100 DEG C for 2-3 hours, and then cooled naturally.

[0041] The silver leaching solution contains 35 g / L silver nitrate and 30 g / L potassium cyanide.

[0042] The silver leaching solution preparation method comprises the following steps: weighing two portions of silver nitrate in proportion, with the first portion and the second portion in a ratio of 4:5 for standby use; then taking two portions of potassium cyanide, with the first portion and the second portion in a ratio of 1:3 for standby use; taking distilled water in a beaker, heating it to 30° C., adding the first portion of silver nitrate and potassium cyanide respectively while stirring, and when the liquid temperature drops to 20° C., adding the second portion of silver nitrate and potassium cyanide respectively while stirring, and the solution can be used after standing for 3 hours.

[0043] Implementation Case 4

[0044] A method for silvering a circuit board. A qualified circuit board is first washed with aviation gasoline for three times, then the surface of the circuit board is evenly scrubbed with a clean wet brush dipped in decontamination powder and Vienna lime, after being scrubbed clean, the decontamination powder and Vienna lime are washed off with running cold water, and then the oxide film on the surface of the copper film of the circuit board is brushed off with a clean wet soft copper wire brush, the cleaned circuit board is put into a clean hanging basket, immersed in silver immersion liquid, immersed at a temperature of 40 DEG C for 5 minutes while shaking continuously, and after being taken out of the tank, the silver immersion liquid is washed off with two streams of clean water, then washed with 60 DEG C hot water, blown dry with compressed air, and then put into an oven for stable treatment, baked at 100 DEG C for 2 hours, and then cooled naturally.

[0045] The silver leaching solution contains 55 g / L of silver nitrate and 50 g / L of potassium cyanide.

[0046] The silver leaching solution preparation method comprises the following steps: weighing two portions of silver nitrate in proportion, with the first portion and the second portion in a ratio of 4:5 for standby use; then taking two portions of potassium cyanide, with the first portion and the second portion in a ratio of 1:3 for standby use; taking distilled water in a beaker, heating it to 40°C, adding the first portion of silver nitrate and potassium cyanide respectively while stirring; when the liquid temperature drops to 20°C, adding the second portion of silver nitrate and potassium cyanide respectively while stirring, and the solution can be used after standing for 3 hours.

Claims

1. A method for silvering a circuit board, characterized in that: For qualified circuit boards, first wash them with aviation gasoline for 2-3 times, then use a clean wet brush dipped in decontamination powder and Vienna lime to evenly scrub the surface of the circuit board, wash off the decontamination powder and Vienna lime with running cold water after scrubbing, then use a clean and wet soft copper wire brush to remove the oxide film on the surface of the copper-clad film of the circuit board, put the cleaned circuit board into a clean hanging basket, immerse it in the silver immersion solution, immerse it at 20-40℃ for 3-5 minutes while shaking it continuously, wash off the silver immersion solution with two streams of clean water after taking it out of the tank, then wash it with 50-60℃ hot water, blow dry it with compressed air, and then put it in the oven for stable treatment, bake it at 90-100℃ for 2-3 hours and keep it warm, then cool it naturally.

2. The method for immersing silver in a circuit board according to claim 1, characterized in that: The silver leaching solution contains 35-55 g / L of silver nitrate and 30-50 g / L of potassium cyanide.

3. The method for immersing silver in a circuit board according to claim 1, characterized in that: The silver leaching solution preparation method comprises the following steps: weighing two portions of silver nitrate in proportion, with the first portion and the second portion in a ratio of 4:5 for standby use; then taking two portions of potassium cyanide, with the first portion and the second portion in a ratio of 1:3 for standby use; taking distilled water in a beaker, heating it to 30-40° C., adding the first portion of silver nitrate and potassium cyanide respectively while stirring, and when the liquid temperature drops to 20° C., adding the second portion of silver nitrate and potassium cyanide respectively while stirring, and the solution can be used after being left to stand for 2-3 hours.

4. The method for immersing silver in a circuit board according to claim 1, characterized in that: The aviation gasoline is No. 150 or No. 180 aviation gasoline with a pH value of 5-6.

5. The method for immersing silver in a circuit board according to claim 1, characterized in that: The purity of the silver nitrate and potassium cyanide is industrial grade.

6. The method for immersing silver in a circuit board according to claim 1, characterized in that: The soft copper wire brush should be softened. First wash it with No. 150 or No. 180 aviation gasoline, then wash it with metal detergent solution at 45℃ for 5 minutes, then wash it with 60℃ hot water for 20S, then wash it with cold water for 20S until the oil stains on the copper wire brush surface are removed, then use copper pickling solution to remove the oxides on the copper wire brush surface, wash it with water, blow it dry, put it in an oven to bake at 180-190℃ for 2-3 hours, cool it naturally in the oven and set it aside.

7. The method for immersing silver in a circuit board according to claim 1, characterized in that: The hanging basket is made of ethylene or polyethylene.

8. The method for immersing silver in a circuit board according to claim 1, characterized in that: The Vienna lime is medical sodium lime.

9. The method for immersing silver in a circuit board according to claim 1, characterized in that: The brush is a pig bristle sx-5510 with a specification of 63mm.

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