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Stop MAsk?

B

Bojan

Jan 1, 1970
0
Can me somebody explain what is "Stop mask" in PCB(P-CAD)? For what use this
layer?
Tnks
 
B

Brad Velander

Jan 1, 1970
0
Bojan,
I have never heard the term "Stop mask" in regards to PCB design. I can
only assume it is some alternate name for soldermask.

The soldermask is typically an epoxy screened on mask layer that is
placed over the copper conductors with openings only where there is a pad
that requires soldering. It helps stops solder from shorting between two
adjacent pads and from wetting along a trace, being pulled away from the pad
that was desired to be soldered.

With a soldermask layer you can move the PCB through a solid wave of
solder (Wave soldering) without the solder attaching to every trace or
copper feature, turning it into a large mass of solder shorting across all
traces. When wave soldering the solder will only attach and flow to the
exposed PCB pads and component leads. Where there is soldermask the solder
will just pull away from the PCB and stay in the wave rather than attaching
to all the traces underneath the soldermask.

As a secondary function it also assists in protecting the copper traces
from moisture and the resulting oxidation/corrosion during handling,
processing and assembly of the PCB.

Brad Velander
 
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