Method for separating and recovering tin coating of PCB by two-segment method

A PCB board, separation and recycling technology, applied in the improvement of process efficiency, photography process, electrodes, etc., can solve the problems of equipment and operators with great harm, difficulty in harmless treatment, and high organic content, and is conducive to operation and transportation. , The effect of reducing the output of nitric acid tin stripping wastewater and high solubility

Inactive Publication Date: 2020-03-31
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, production practice has proved that the nitric acid type tin stripper still has certain shortcomings: 1. The content of nitric acid is too high, which makes the tin stripper itself harmful to equipment and operators during transportation, storage and use; 2. Stability Poor, it is easy to produce white precipitation during use, and block the equipment; 3. The tin stripping wastewater has the characteristics of high residual acidity, high heavy metal content, and high organic content, which makes its harmless treatment difficult and easy to cause major harm to the environment
However, there are many problems in the use of chloride salt system, such as hydrochloric acid volatilization deteriorates the operation workshop, hydrochloric acid corrodes equipment, and low electrolysis efficiency, etc.

Method used

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  • Method for separating and recovering tin coating of PCB by two-segment method
  • Method for separating and recovering tin coating of PCB by two-segment method
  • Method for separating and recovering tin coating of PCB by two-segment method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] The method for separating and reclaiming the tin coating of PCB board by two-stage method comprises the following steps:

[0031] 1) prepare electrolyte: electrolyte is made up of tin salt, acetic acid, acetic acid salt, complexing agent, additive and deionized water, and wherein stannous sulfate concentration is 120g / L, and acetic acid concentration is 100g / L, and sodium acetate concentration is 50g / L, the concentration of citric acid + methanesulfonic acid is 40g / L, add 3g / L mixture of gelatin, calcium lignosulfonate and hydroquinone with a mass ratio of 1:1:1 to the electrolyte, stir and mix well ,spare;

[0032] 2) Prepare the second stage of tin stripping solution: the second stage of tin stripping solution is composed of nitric acid, ferric nitrate, copper protecting agent and water, wherein HNO 3 Concentration is 200g / L, Fe(NO 3 ) 3 The concentration is 100g / L, the concentration of benzotriazole is 8g / L, thiourea 5g / L, sulfamic acid 5g / L, sodium chloride 5g / L,...

Embodiment 2

[0038] The method for separating and reclaiming the tin coating of PCB board by two-stage method comprises the following steps:

[0039] 1) Prepare electrolyte: electrolyte is made up of tin salt, acetic acid, acetate, complexing agent, additive and deionized water, and wherein stannous sulfate concentration is 50g / L, and acetic acid concentration is 100g / L, and sodium acetate concentration is 50g / L, the concentration of citric acid + ethylenediaminetetraacetic acid is 50g / L, add 4g / L mixture of gelatin and polyethylene glycol 600 with a mass ratio of 1:1 in the electrolyte, stir and mix well, set aside;

[0040] 2) Prepare the second stage of tin stripping solution: the second stage of tin stripping solution is composed of nitric acid, ferric nitrate, copper protecting agent and water, wherein HNO 3 Concentration is 200g / L, Fe(NO 3 ) 3 The concentration is 100g / L, the concentration of benzotriazole is 8g / L, thiourea 5g / L, sulfamic acid 5g / L, sodium chloride 5g / L, stir and m...

Embodiment 3

[0046] The method for separating and reclaiming the tin coating of PCB board by two-stage method comprises the following steps:

[0047] 1) Preparation of electrolyte: electrolyte is composed of tin salt, acetic acid, acetate, complexing agent, additive and deionized water, wherein the concentration of stannous acetate + stannous methanesulfonate is 150g / L, and the concentration of acetic acid is 140g / L, the concentration of potassium acetate is 60g / L, the concentration of methanesulfonic acid is 60g / L, gelatin, polypropylene glycol 400, catechol and Sodium lauryl sulfate mixture additive, stir and mix well, set aside;

[0048] 2) Prepare the second stage of tin stripping solution: the second stage of tin stripping solution is composed of nitric acid, ferric nitrate, copper protecting agent and water, wherein HNO 3 Concentration is 200g / L, Fe(NO 3 ) 3 The concentration is 100g / L, the concentration of benzotriazole is 8g / L, thiourea 5g / L, sulfamic acid 5g / L, sodium chloride...

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Abstract

The invention discloses a method for separating and recovering a tin coating of a PCB by a two-segment method. The method comprises the following steps: 1) a first segment: an anode plate and a cathode plate are placed in an electrolytic bath filled with electrolyte and introduce direct current for electrolysis, and partial tin coating on the surface of the PCB is removed, wherein the anode plateis formed by combining the PCB and a conductive hard metal mesh, and the electrolyte comprises tin salt, acetic acid, acetate, a complexing agent and an additive; 2) a second segment: the PCB treatedin the step 1) is placed in an HNO3-Fe(NO3)3 system, the residual tin coating on the PCB is removed, and the qualified PCB is obtained. According to the method, the tin coating of the PCB can be efficiently, cleaned, safely and conveniently separated, most of tin can be recovered in the form of metal, the metal substrate feature, thickness and performance of the obtained PCB are good, and the PCBcan meet factory requirements.

Description

technical field [0001] The invention relates to the technical field of printed circuit board manufacturing, and more specifically, relates to a two-stage method for separating and recycling the tin coating of a PCB board. Background technique [0002] The main function of the printed circuit board (PCB for short) is to connect various electronic components to achieve circuit conduction, which has changed the previous mode of relying on wires to connect electronic components. Since the first printed circuit board came out in the 1940s, printed circuit technology has been continuously upgraded and updated, driving the rapid development of the PCB industry. As of 2018, the global PCB industry has reached 62.396 billion US dollars. The PCB manufacturing process roughly includes processes such as photolithography, image transfer, etching, drilling, hole metallization, surface metal coating, and organic material coating. Tin plating is often used as a protective layer during imag...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25C1/12C25C1/14C25C7/02C25F5/00C25F7/00
CPCC25C1/12C25C1/14C25C7/02C25F5/00C25F7/00Y02P10/20
Inventor 唐朝波邓鑫杰杨建广杨声海陈永明何静
Owner CENT SOUTH UNIV
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