PCBs seem to be getting more complex by the day, so it is important for designers to keep educating themselves about the realities of manufacturing increasingly intricate boards.

Last month’s column highlighted design considerations for the strip-etch-strip process and how manufacturers approach that phase of production. Now that we have a functioning board, we must protect the PCB from environmental hazards and document the circuit components.

This article will detail the solder mask and legend process and offer best practices for designers to ensure a high-quality result.

Board Inspection

Before the process begins, inspect the boards to ensure the plating and etching are effective and that the PCB meets customer functionality requirements. There are two inspection methods to choose from: visual inspection and automated optical inspection (AOI).

A visual inspection under magnification by an inspector is adequate for simpler designs. Inspectors examine board components for various issues and reject those that do not meet quality standards.

For more complex, higher-density boards or PCBs where a customer requests higher than Class 2 IPC-A-600 inspection, we use an AOI process that performs a near pixel-to-pixel comparison between the physical board and the original design data.