Homebrew PCBs

Trevor White <trevor.white100@...> writes:
> How do you bond a 4 layer board together?

Double sided tape.  I adhere the tape to the out layers, drill the
"blind" vias (oversized), stick everything together, then drill the
through-vias.

The hardest part is getting a good solder connection between the outer
and inner layers.

Because of the added difficulty, I only use them when I have tricky
power/ground distribution problems.  So far, I've done it twice:

http://www.delorie.com/electronics/usb-gpio/
http://www.delorie.com/electronics/sdram/

For the USB board, I ended up redesigning it as a two-layer board for
production.  The SDRAM board is a one-off.