What is the reason for the uneven etching of aluminum alloy?How to exclude?

What is the reason for the uneven acid etching of aluminum alloy?How to exclude?

I. causes:

1. Insufficient development time and excess glue on the board surface

2. Overexposure

3. Delayed development after exposure

4. After pre-drying, it was placed too long without timely exposure

Ii. Corresponding exclusion methods:

1. Strengthen the quality management of development

2. Shorten exposure time

3. Develop in time after exposure

4. The pre-baked workpiece shall be exposed and developed in time, and the pre-baked workpiece shall be completed on the same day