Printed circuit board processing method adopting etching process for forming backdrilled holes

Abstract

The invention discloses a printed circuit board processing method adopting an etching process for forming backdrilled holes. The method comprises the following steps: 1) completing normal drilling and electroplating on the surface of a printed circuit board; 2) pasting a layer of dry film on the surface of the printed circuit board; 3) removing the dry film in positions other than to-be-backdrilled positions with a chemical, only reserving the dry film in positions to be backdrilled, and reserving chemical via holes in the dry film at the holes; 4) performing tinning in the holes and in positions without the dry film on the printed circuit board; 5) removing the dry film with the chemical and exposing the to-be-backdrilled positions; 6) etching the holes to the required depth; 7) removing the tin layer on the printed circuit board and the hole walls. The etching process replaces backdrilling, etching is more clean and thorough and has no requirements for the medium thickness, Stub is more uniform, and accordingly, signals of the printed circuit board cannot be influenced, the product quality is good, and the rejection rate is low.

Description

technical field [0001] The invention relates to the field of printed circuit board manufacturing, in particular to a circuit board processing method for making back-drilled holes by an etching method. Background technique [0002] At present, in the production of multi-layer circuit boards, the back drilling of L1-L2 or Ln-Ln-1 is drilled through the drilling machine to control the depth. However, due to the limited accuracy of the machine, in many cases the required medium thickness It is often contrary to the dielectric thickness of the signal design. At the same time, due to the influence of plate curvature and thickness uniformity during mechanical drilling, the stub residue during back drilling is quite different, which will have a greater impact on the signal of the circuit board. Contents of the invention [0003] At present, in the production of multi-layer circuit boards, the back drilling of L1-L2 or Ln-Ln-1 is drilled through the drilling machine to control the ...

AI Technical Summary

Problems solved by technology

[0002] At present, in the production of multi-layer circuit boards, the back drilling of L1-L2 or Ln-Ln-1 is performed by the drilling machine with controlled depth drilling. However, due to the limited accuracy of the machine, the required dielectric thickness in many cases is often contrary to the dielectric thickness of the signal design. At the same time, due to the influence of factors such as board curvature and thickness uniformity during mechanical drilling, the stub residue during back drilling is quite different, which will have a greater impact on the signal of the circuit board.