Dave's common drill rack

From HBRC WIki

This table is the result of comparing the "free" drill racks and the design rules from APCircuits, PCBExpress, and Olimex. I've also used this same library with BatchPCB. This doesn't mean you can't use other drills, but you will be charged for any drill size not in the "free" rack. The pad sizes are chosen such that for a given drill, the minimum annulus is met for any vendor.

Using this drill rack, I created my footprint library around these rules:

• 8 mil minimum line
• 8 mil minimum space
• 8 mil minimum annulus
• 10 mil minimum silk
• 10 mil minimum mask feature
• 8 mil mask swell (mask diameter = pad dia + 8 mil)

Note that minimum pads will be pretty small for hand soldering. Some vendors support finer feature sizes, but these rules are conservative enough that you have lots of fabrication options.

Lib   Olimex    APCircuits (fin)  PCB Express (fin)  min PAD dia.
.020   NO!       .020 (.017)        (.020)           .037
.028   .028      .028 (.025)        (.025)           .044 
.035   .035      .035 (.032)        (.036)           .052
.038   .039      .038 (.035)        (.036)           .052
.042   .043      .042 (.039)        (.043)           .059
.052   .051      .052 (.049)        (.053)           .069
.060   .059      .060 (.057)        (.061)           .077
.086   .083      .086 (.083)        (.0875)          .104
.125   .130      .125 (.122)        (.126)           .142
.152   extra$    .152 (.149)        (.151)           ----  #6 mounting hole

• lib is the specified drill size, vendors will map that to their drill
• numbers in vendor column are: <drilled size> ( <finished size> )
• "min pad" meets design rule for any vendor for "lib" drill size.
• please report errors to Dave Curtis