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removing bits from tStop

autodeskguest

Hi All,

 

I am laying out a PCB that has a footprint for a module that is a PCB with

side-plated contacts.

 

Underneath the module there are a few vias and I am concerned they might

short with vias on the underside of the PCB module.

 

I thought that I coule edit tStop and remove the stop on the top layer, so

that the vias are completely covered on the top, but open on the bottom.

 

Firstly, is it safe to do this, and secondly, how do I edit the tStop layer.

When I view it, I just see hatched circles where the vias are, but I dont

seem to be able remove them.

 

All hints suggestions and ideas welcome!

 

Thanks,

Chris

 

 

 

Parents

  • Quote:

    only for careless board houses. Serious manufacturers know the risks.

     

    Take a look at most circuit boards, and you will see the vias covered with

    soldermask.  Apparently someone here had a bad day possibly caused by dirt

    trapped under the soldermask which then corroded the via.  Yes, I suppose

    careless board houses can run into that, but that doesn't make the overall

    concept wrong.

     

    I once had a problem with a run of boards that failed months after getting

    into the field.  This was eventually traced back to sloppy board

    manufacture.  A connector was used with relatively fine pitch, 1.25mm if I

    remember right.  The PCB material was not made correctly, so there were

    small voids in it.  Chemical residue got stuck in the voids, which over

    time either shorted out adjacent pins directly or caused metal atoms to

    migrate which then caused shorts.  Some were only a few ohms between

    adjacent pins.  A few boards failed by overheating when the power and

    ground pins on the connector got shorted.

     

    Anyway, the point is stuff goes wrong, but don't blame it on the wrong

    thing or believe in mythological solutions.  What you're saying about the

    solder mask is like saying I should never use a 1.25mm connector again

    because one board house made bad PCBs that run.  Clearly that would be

    silly.

     

    I've also had manufacturing problems with QFN packages.  The manufacturer

    did something to leave water soluable flux residue under the QFN package,

    and a bunch of pins were essentially shorted together.  Your equivalent

    solution would be to never use a QFN package again.

     

    --

    Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

     

Reply

  • Quote:

    only for careless board houses. Serious manufacturers know the risks.

     

    Take a look at most circuit boards, and you will see the vias covered with

    soldermask.  Apparently someone here had a bad day possibly caused by dirt

    trapped under the soldermask which then corroded the via.  Yes, I suppose

    careless board houses can run into that, but that doesn't make the overall

    concept wrong.

     

    I once had a problem with a run of boards that failed months after getting

    into the field.  This was eventually traced back to sloppy board

    manufacture.  A connector was used with relatively fine pitch, 1.25mm if I

    remember right.  The PCB material was not made correctly, so there were

    small voids in it.  Chemical residue got stuck in the voids, which over

    time either shorted out adjacent pins directly or caused metal atoms to

    migrate which then caused shorts.  Some were only a few ohms between

    adjacent pins.  A few boards failed by overheating when the power and

    ground pins on the connector got shorted.

     

    Anyway, the point is stuff goes wrong, but don't blame it on the wrong

    thing or believe in mythological solutions.  What you're saying about the

    solder mask is like saying I should never use a 1.25mm connector again

    because one board house made bad PCBs that run.  Clearly that would be

    silly.

     

    I've also had manufacturing problems with QFN packages.  The manufacturer

    did something to leave water soluable flux residue under the QFN package,

    and a bunch of pins were essentially shorted together.  Your equivalent

    solution would be to never use a QFN package again.

     

    --

    Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

     

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