Fabrication method for printed circuit board with golden finger coated with gold on four surfaces

Abstract

The invention discloses a fabrication method for a printed circuit board with a golden finger coated with gold on four surfaces. The fabrication method comprises the following steps of 1) fabricating a primary outer-layer circuit pattern, and fabricating all circuit patterns containing golden finger lines; 2) carrying out first etching after pattern electroplating; 3) carrying out first solder welding, and partially windowing the golden finger lines; 4) fabricating a secondary outer-layer circuit pattern, covering a dry film except a golden finger region, and electroplating nickel and gold on the golden finger region; 5) carrying out third outer-layer circuit pattern after the dry film is removed; and 6) carrying out second etching, removing the covered film and then carrying out second solder welding. With the adoption of the two-time solder welding process, the height difference existing between a copper surface and a substrate is improved, the problems of nickel permeation caused by unfirm dry film coverage after the fabrication of the primary outer-layer circuit pattern and the secondary outer-layer circuit pattern and copper leakage of the golden finger caused by medicine liquid hidden under the dry film to affect the performance of the circuit board are solved, and the problem that a normal circuit is corroded due to excessive medicine liquid etched during lead etching is further improved.

Description

technical field [0001] The invention belongs to the technical field of printed circuit board manufacturing, and in particular relates to a method for manufacturing a printed circuit board with gold fingers on four sides. Background technique [0002] If you want to connect two printed circuit boards (PCBs) to each other, you will generally use a side connector commonly known as a gold finger. It is connected with the line area to transmit signals. Traditional gold fingers are generally covered with gold on the top surface and both sides of the finger, that is, gold on three sides. With the development and progress of technology, people have higher and higher requirements for PCB. Now it is often necessary to plate gold on the top surface, both sides and the front surface of the gold finger. The front end of the finger needs to be connected to the inner layer by drilling holes, or it can be connected to the inner layer circuit by setting leads in the effective unit of the PC...

AI Technical Summary

Problems solved by technology

[0005] The above method has the following technical problems: after the first circuit etching, due to the height difference between the copper surface and the substrate surface, the dry film is not firmly pasted, and nickel seepage occurs, and the hidden liquid under the dry film causes the gold finger to leak copper; the second When the leads in the sub-unit are etched, the dry film window is prone to over-etching and etching to other circuits. Third, when the front of the finger is etched behind the leads, it is easy to appear hanging gold, and a gap is formed after the hanging gold is recessed.