Jerry,
 
 Compaq has also realized an order of magnitude improvement in their 
 assembly DPPM by going to BGA. Would that cover the cost difference?
 
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______________________________ Reply Separator _________________________________
Subject: BGA's - one user's perspective
Author:  [log in to unmask] at corp
Date:    1/12/96 1:29 PM


Seems like everything I pick up these days has an article about BGA's and 
how they will revolutionize the world. From the talk at the shows, the 
magazine articles, and they equipment brochures I've read in the last year 
or so, you'd think they were flooding the market.
 
I'm still skeptical.
 
They have a benefit, and for pin counts above 200, some real practical 
advantages in processing and reliability.
 
We have built exactly 8 units here with PBGA's. All protos, done by hand on 
one new board design here. They worked easily enough. We have discussed 
putting three in-house designed ASIC devices in this package. All three are 
still in QFP's - the reason is that the cost is incrementally about 30% 
higher for the devices we have actually quoted packaged in a PBGA vs. a 
QFP304 (about $65 vs. $50).
 
Until we see the semiconductor manufacturers offering this wonderful, 
fantastic package at a similar cost, I doubt anyone can argue sucessfully 
how to save $15 per board by going to a BGA. I do not understand why it is 
so much more expensive than conventional molded packages with stamped 
leadframes, but it is in our experience.
 
Of course, it is extremely difficult to make, handle, place, and solder 
these monster QFP's with 0.5 mm pitch, I do not like them, either. It's 
just that I think we can put them down for a good deal less than $15 
apiece.
 
If we were Compaq, and buying a few hundred thousand a month, I am sure 
we'd be getting better price. I understand they are getting all their high 
pin count devices in PBGA's now. Maybe they will drive this market, and 
things will change soon.
 
This is an interesting development in the field of IC packaging, and it has 
merit. For many of us, it is not yet a significant issue, and it may be a 
number of years before it is commonly used by the broad spectrum of circuit 
board designs.
 
 
 
cheers,
 
Jerry Cupples
Interphase Corporation
Dallas, TX
http:www.iphase.com