Method for achieving chemical nickel plating by activating surface of PCB

Abstract

The invention discloses a method for achieving chemical nickel plating by activating the surface of a PCB and belongs to the field of printed circuit board manufacturing. The method comprises the following steps that 1, 0.01-10 g / L soluble silver salt is prepared to serve as a silver soaking solution; 2, activating liquor is prepared from 1-100 g / L pH stabilizer and 10-50 g / L reducing agent, wherein the pH stabilizer is one or more of sodium hydroxide, potassium hydroxide, ammonia water, sodium acetate and the like, and the reducing agent is one or more of formaldehyde, acetaldehyde, glyoxylic acid, methyl alcohol, vitamin C, citric acid and the like; 3, pretreatment of the PCB is conducted; 4, the PCB is soaked in the silver soaking solution for 10-120 seconds after pretreatment, washed and then soaked in the activating liquor for 10-80 seconds; and 5, the PCB obtained in the step 4 is placed in chemical nickel-plating liquor for chemical nickel-plating. According to the method for achieving chemical nickel plating by activating the surface of the PCB, no precious metal palladium is used during activating; the stability of the activating liquor is high; diffusion coating is avoided; and the production cost of the PCB is effectively reduced.

Description

technical field [0001] The invention belongs to the field of printed circuit board (PCB) manufacturing, and in particular relates to a palladium-free activation method before electroless nickel plating on the copper circuit surface of the printed circuit board (PCB). Background technique [0002] A printed circuit board (PCB) is an interconnect that provides electronic component connections through copper circuits on its insulating substrate, and is a support for electronic components. However, in the process of PCB production and use, circuits made of copper are easily oxidized, resulting in deterioration of electrical conductivity and soldering performance. Therefore, surface treatment of copper circuits is necessary to improve the corrosion resistance and soldering performance of copper circuits. Electroless nickel plating / gold displacement plating technology is electroless nickel plating on the surface of copper circuits followed by gold displacement plating. The nickel / ...

AI Technical Summary

Problems solved by technology

However, as the price of precious metal palladium continues to soar in recent years, the cost problem of the palladium activation method applied before electroless nickel plating on the surface of copper circuits has become increasingly significant, which has brought a huge impact on PCB production cost control; at the same time, the palladium activation solution itself Metastability and the resulting permeation phenomenon in electroless nickel plating have further increased the cost of PCB manufacturing. Therefore, the development of a new low-cost, high-activity, high-stability and easy-to-operate palladium-free activation method is beneficial to the PCB manufacturing industry. said to be of great significance

[0004] S.Yagi et al. use TiCl 3 As a reducing agent, the nickel ions in the solution are directly reduced to metallic nickel to obtain a nickel coating on the surface of the copper circuit. Although this method can eliminate the activation process before the electroless nickel plating on the copper surface and directly obtain metallic nickel on the copper surface, the chemical The deposition rate of nickel plating is too low, resulting in low production efficiency, and the stability of the plating solution is poor, easy to decompose, and expensive

Tian Dong et al. utilized the difference in the stability constants of thiourea and monovalent copper ions and nickel ion complexes to realize the electroless nickel plating on the surface of copper lines on printed circuit boards caused by the displacement nickel plating method instead of the palladium activation method; The time is much longer than palladium activation and it is easy to cause catalyst poisoning caused by doping thiourea in the coating

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