Microvias and BGA Pads

[Inka_One]

Hey to you folks!

I wish to know if I could place microvias under a BGA pad.

What's the problems if I do that?

Best regards for all!

 

[shaiko]

You can and I've seen it done.
Whether it's a good and advisable practice - probably not.

IMHO, there's a ball pitch to via diameter ratio below which the joint integrity becomes unreliable. In some cases - the ball may detach completley from the IC.

 

[marce]

Yes, its standard practice for HDi PCB design.

 

[loosemoose]

Google "Via-In-Pad".