Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

I just got a 36x2 way card extender type edge connector, 0.156 pitch to fit the card extender PCB I made with toner transfer printed with my HP Laserjet 4050.

I found that the PCB I so carefully created in my PCB design package has ended up slightly oversized - over the 36 ways the distance from first to last should be 5460 mils and is shown as such in the PCB design software. The finished PCB is larger at 5490 mils over this distance, which doesn't sound a lot, but that's about 0.76mm which isn't a trivial error.

The whole board should be 8.1875" (207.9625mm) but the printed outline is actually 209mm. So call that a 1mm error which is HUGE.

This works out to be about 1.005 times the size it should be.

In this case, there's (just) enough leeway for the board to still work as a card extender without things shorting or failing to connect, but in general this level of error is a disaster.

The printer driver won't scale except in full percentage points, and while 99 percent is closer to 99.45% than 100%, it isn't right.

Has anyone worked out a good solution to this problem.

HELP!
Dave