Re: gEDA-user: Cheap 4 layer manufacturer?

[marvindickens@xxxxxxxxxxxxx]

> > I bumped the ball size down from the Xilinx recomended 0.4mm to 0.34mm,
> > and everything worked out fine. 

In our experience, bumping down pad size can be a dangerous thing. I'd be 
carefull and test a few before I had that many made. The issue is not whether 
you can attach a bga device to down sized pads, but if it will stay attached 
through time. In essence, I am suggesting that down sizing the pad can 
emulate bad printing, device warpage and/or PCB warpage. Printing is talked 
about here:

http://www.aimsolder.com/techarticles/tech sheet BGA voiding- reducing through 
process optimization.pdf

The rest is talked about here:

http://www.akrometrix.com/pdf/Tech_Papers/CSP Board Level Reliability.pdf


Best regards

Marvin