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Engineering Question 9: Solder mask opening on bottom layer only
Posted on 25/11/2016

Solder mask appications are usually simple and easy to follow on a Computer Aided manufacturing (CAM). Sometimes, depending on the quality and clarity of the PCB design file package received, PCB Global’s Engineering department will invariably have a few Engineering Questions, also known as, EQ’s to confirm. One example involving a typical EQ is for issues with solder masks is shown below:

Solder mask opening on bottom layer only

EQ from CAM:

Top layer has standard solder mask opening on the pads but bottom layer does not.


The solder mask files are generally open for all SMT and through hole pads, these 4 pads have plated through holes with no the solder mask opening on the bottom layer.


Our customer confirmed to apply the solder mask as per file as these 4 pink highlighted pads on the top layer are sometimes soldered together to make a connection for certain options on the PCB.

For further tips and information when designing and laying out your printed circuit board design file please do not hesitate to contact our PCB Global team at sales@pcbglobal.com