A method for removing suspended copper in blind holes of circuit boards

Abstract

The invention relates to a method for removing suspension copper in a blind hole of a circuit board, belonging to the technical field of chemical industry. The method comprises the following steps of (1) respectively preparing a liquid A and a liquid B, wherein the liquid A comprises an acidic or alkaline substance and a wetting agent, and the liquid B comprise one or more of hydrogen peroxide, peroxysulphate, nitrate, hypochlorite, copper sulfate and ammonium chloride substances; (2) respectively heating the liquids obtained in the step (1) to be 20-60 DEG C; and (3) immersing a workpiece with suspension copper in the blind hole in the liquid A for 1 to 10 minutes, taking out the workpiece, dropping the liquid for several seconds, immersing the workpiece in the liquid B for 1 to 10 minutes, and finally washing and drying the workpiece. By the method, chemical etching can be carried out on the suspension copper in the blind hole, and no etching is carried out on copper outside the hole and copper at the bottom of the hole. The process is simple, economic and efficient.

Description

technical field [0001] The invention relates to a method for removing hanging copper in a blind hole of a circuit board, in particular to an AB liquid method for chemically etching the hanging copper in the blind hole without substantially etching the copper outside the hole and the copper at the bottom of the hole, and belongs to the technical field of chemical industry. Background technique [0002] With the miniaturization and high-speed development of intelligent electronic products, printed circuit boards are advancing in the direction of high density, high integration, small holes, and large capacity. Taking drilling as an example, HDI boards have made mechanical drilling reach the limit; for blind buried tiny holes, mechanical drilling methods can no longer meet the requirements. Therefore, laser drilling technology capable of processing tiny holes is becoming more and more popular. When the aperture is as small as the micron level, laser drilling also creates new pr...

AI Technical Summary

Problems solved by technology

If the hanging copper is not removed, poor electroplating problems such as copper nodules and voids will occur in the electroplating process

[0003] Chinese patent CN103014825A proposes to remove the suspended copper of the printed circuit board and the packaging substrate by anodic electrolysis. Although the electrolysis process takes a short time, there is still corrosion to the copper outside the hole and the copper at the bottom of the hole, and the production capacity is limited, which is not as large as the chemical solution method.

Ruishixing RS-859 laser copper clad remover removes suspended copper by solution method. Although it can etch suspended copper at high speed and corrode surface copper at low speed, there is still the problem that surface copper and bottom copper will be bitten.