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Engineering Question 1: Non-Plated Through Hole Cutting into Copper
Posted on 27/11/2015

Depending on the quality of the PCB design file package received, PCB Global’s Computer Aided manufacturing (CAM) Engineering department will invariably have a few Engineering Questions, also know as, EQ’s to confirm. One example of a typical EQ is shown below:

Non-Plated Through Hole Cutting into Copper

EQ from CAM:

These 2 non-plated through holes during CNC drilling will intrude and cut into the copper Surface-Mount Technology (SMT) pads as highlighted below (see image).

Explanation:

As a rule, SMT pads must not to be cut or drilled especially with a non-plated hole as this process is fabricated during the final route stage when all the surface finish (immersion Gold, HASL, OSP, Immersion Silver, etc.) has been applied. Therefore, drilling now will result in an exposed copper area on the SMT pads.

Resolution:

In this case with the customer’s approval we shaved the SMT pads by 2mil to ensure no exposed copper.

 

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