Doug,

First and foremost, get directly involved with your customer at the PCB design 
stage. The type and quantity of BGA devices will affect layer count, internal 
and external routing, test-ability, and soldermask apertures.

I have seen all types of surface finishes specified; HASL, OSP, hard and soft 
Ni/Au, and solid solder deposits. I know of one fabricator that supplies BGA 
product with solder bumps on the all SMD sites but the BGA with the BGA and 
PTH sites OSP. The assembler does not print any paste, just sticky flux for 
the SMD's. They're using BGA's with 63/37 balls which supply the solder to 
the joints.

Probably the most significant impact on the PCB fabricator is at electrical 
test. Depending on your technology level of fixturing software, fixturing, 
and test equipment, you can easily get into multiple test fixtures that take 
many hours to solve. Getting involved early in the PCB design can prevent
having 4-625 pin CBGA's in a 3"x3" area.


Regards,

Dennis Mitchell
Zycon Corp.
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______________________________ Reply Separator _________________________________
Subject: BGA
Author:  [log in to unmask] at corp
Date:    1/10/96 5:32 PM


-- [ From: Doug Jeffery * EMC.Ver #2.10P ] --
 
 
Question?
 
What does BGA technology mean to board fabricators?  Do we have to 
become solder paste experts and reflow solder again.. I thought we got 
rid of that problem.....:)....
 
  No Seriously, what are the responsibilities at fabrication for
creating boards to accept BGA's?
 
Thanks?
 
Doug Jeffery
Electrotek..