Mail Archives: geda-user/2018/07/12/16:05:19
Hello,
Some questions with regard to thermals.
1: When I create small vias with a thermal, e.g. 0.3 mm drill width,
0.15 mm annulus width and 0.15 mm clearing, the resulting four thermal
connections to the surrounding copper plane get so narrow (just below
0.125 mm), that my PCB manufacturer flags a warning.
Also, the PCB is placed in a higher (and rather more expensive)
technology class.
The only way to make these thermal connections wider, is to increase the
clearance in polygons, but that isn't always desirable, as it eats away
at the conducting area of any unconnected copper planes.
Or is there another way to increase the width of those thermal connections?
2: SMD thermals, or the lack thereof. If I really need thermals, I
create tiny rectangles without clearance (S key) to connect pads to the
surrounding copper planes.
The other, 'lazy' solution is to simply set the clearance of the pad so
low (with Shift+K) that the pad is completely engulfed in the copper plane.
However, I understand that this may cause problems, not just in the case
that I manually want to remove the component, but also in the actual
reflow process ('tombstoning'). So is it better to always use home-made
thermals? Because that is a bit of a hassle.
Thanks for any thoughts on this.
Best regards,
Richard Rasker
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