Three Issues of Etching in Multilayer PCB Manufacturing

Three Issues of Etching in Multilayer PCB Manufacturing

In multilayer PCB manufacturing, etching is an indispensable step in both inner-pattern transfer and outer-pattern transfer. The purpose of etching is to remove non-line part of the Copper.

Etching

1.What solution do we need to finish etching?

Commonly, in negative etching, we mainly use two kinds of mixed solution: 1. Hydrochloric acid and hydrogen peroxide. 2. Sodium hypochlorite and hydrochloric acid. Etching solution and ammonia are mainly used for positive etching. However, the final decision of acidity or alkaline is determined by process of PCB manufacturers.

2.Why remove the protective film before etching in outer-pattern transfer?

Prior to the transfer of the pattern, the protective film is used to protect the non-wiring part from any reaction before etching, and then to increase the copper thickness of the wiring part to meet the requirements of the customer. Then, the removal of the protective film is for the non-line part of the Copper that we don’t need to be etched away.

3.Why do we need to check in AOI after etching?

AOI inspection in the multilayer PCB manufacturing is also essential, but why do we have to check in AOI after the end of etching? AOI examination is to scan pattern, completing with the original design of the contrast.

By introducing the three issues in the etching process, do you have a deeper understanding of etching in multilayer PCB boards manufacturing？And hope that these can help you.