Guys,
Allow me another question regarding pads. When is a pad too big. It can be too small by some definition.
Davep238 offered that “pad size should be at least + 0.010” [10mil] over finished hole size for vias and + 0.014" [14mil] over finished hole size for component holes. This means the annular ring (radius of the pad) should be at least .005" [5mil] for vias and a minimum of 0.007" [7mil] for component holes".
So, I know what the minimums look like. What about going bigger. I love bigger, higher, and heavier. So, when is more too much. Here is my example. I want to load 17 LEDs in a row, so I want to make sure I plan it correctly. The basic footprint of a 5mm LED has a pad 50 mils OD x 31 mils ID. The width of the Eagle library trace, or annular ring, is 10 mils wide. In the interest of economy and space, I guess that is ok. But if I want more “meat” and do not have a space problem? Is there any reason why I cannot or should not increase the OD to some “standard” sizes like 66, 70, 77, or 80 mils OD? I call them standard sizes because they are default settings in the Eagle pull down menus. Obviously, with a 5mm LED, at 80 mils for pad sizes, you reduce your clearance between leads to 20 mils, so there are practical limits. But if 20 mils is OK for a clearance, what about the 80 mils for a pad OD? I can see where with ever larger pads, maybe it would start to take more heat to make a good joint at the expense of degrading the LED ? I do not know.
The feedback on pad drill sizes was very helpful and calming, to learn so much. It is now midnight, here in New Jersey. I should probably head for bed.
Thanks in advance.
Bill M