Hi Earl,
About CBGA's, I just uploaded a very interesting document called "Ceramic Ball Grid Array Assembly Reliability in Military Applications" to www.smtinfo.net/docs/bga_80775_c.pdf It's about the assembly process with Kyocera's dimpled CBGA, with SnPbBi solderballs (melting point close to eutectic solder). Really good stuff, including results of reliability studies.
Best regards,
Daan
----- Original Message -----
From: Earl Moon
To: [log in to unmask]
Sent: Thursday, February 07, 2002 9:41 PM
Subject: [TN] Ceramic CSP's and BGA's in general
Kind folks of the IPC TechNet and those not so but well informed concering
the subject issue - for me.
I have gone back and re-read all the articles and papers concerning ceramic
packages, but for CCGA's. I am, as some of you in the past, about the great
CTE mismatch between ceramic, silicon, and MLB's without constraining or
tailoring core materials.
My "frinds" at TI and IBM have been the primary players in this game. TI's
approach to solder balls is using eutectic types - I belive though not
certain in every instance. IBM talks to hard balls (90% lead) instead - in
most cases as I again believe.
I like the hard ball approach because no collapse, of course, is effected
during reflow. Therefore, more hot air is allowed to "circulate" under and
between the balls effecting a better solder joint consistently.
I am hopeful, some of you can shed some light with positive experiences with
the aformentiond parts and their solder joint acceptable initially, and long
term reliability. Realizing we have gone down this pass a few times, I hope
there is some "new" information besides the great stuff the two companies in
question provide.
As a lover of CCGA's, past and present, by IBM, I wish these parts could use
this technology. It works first and always.
Beyond this, I am hoping TI, as a major DSP device supplier, proves its
plastic BGA (super BGA or perimeter BGA - whichever) does the job. It is
said they are packaging four chips in this package style making it lower
cost and certainly more reliable due to the CTE issue.
Any input appreciated,
MoonMan
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