A method for activating the surface of pcb circuit to realize electroless nickel plating

Abstract

The invention discloses a method for activating the surface of a PCB circuit to realize electroless nickel plating, which belongs to the field of printed circuit board manufacturing. The method comprises the following steps: 1) preparing 0.01-10 g / L soluble silver salt as a silver immersion solution; 2) preparing an activation solution according to the ratio of 1-100 g / L pH stabilizer and 10-50 g / L reducing agent, and the pH stabilizer is hydrogen One or more of sodium oxide, potassium hydroxide, ammonia water, sodium acetate, etc., and the reducing agent is one or more of formaldehyde, acetaldehyde, glyoxylic acid, methanol, vitamin C, citric acid, etc.; 3) Pretreatment of PCB board; 4) After pretreatment, the PCB board is immersed in the immersion silver solution for 10-120s, cleaned, and then immersed in the activation solution for 10-80s; 5) The PCB board obtained in the previous step is chemically nickel plated. The invention avoids the use of precious metal palladium in the activation process, the activation solution has high stability and no seepage phenomenon, and effectively reduces the PCB production cost.

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

Images