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May 1999

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Subject:
Re: BGA Solder joint reliability
From:
"Alderete, Michael" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 13 May 1999 08:51:19 -0700
Content-Type:
text/plain
Parts/Attachments:
text/plain (78 lines) 
Re-sending...TechNet rejected last night's attempts to post, requiring
resubscription!
-michael

-----Original Message-----
From: Alderete, Michael
Sent: Wednesday, May 12, 1999 6:08 PM
To: 'IPCtechnet'
Cc: [log in to unmask]
Subject: re: BGA Solder joint reliability


Li-

1) Is this a full array of BGA balls, or a perimeter array?
2) In larger packages, are balls under die, or edges of die?
3) Is the cross section, and hence construction, of both types known to you?
If your aren't sure, a cross section on each type will confirm this,
including die and bond line thickness, (BT) substrate thickness, etc.
4) I'm not too familiar with TBGA construction. Could it be that BT
substrates are much stiffer (in x-y plane) than TBGA? Also, are there heat
spreaders in these packages?


-Michael Alderete

Li Yuan wrote...
------------------------------

Date:    Wed, 12 May 1999 13:11:40 -0600
From:    LI YUAN <[log in to unmask]>
Subject: BGA Solder joint reliability

Dear BGA Reliabilty Experts:

I have done FEM simulations for BGAs and have found some results I cannot
explain. Hope you can enlighten me on it.

I modeled BT-based BGAs and tape-based BGAs (both cavity up) under 0-100C
1 cycle per hour condition. For BT BGAs, with the same die size, the
larger the package, the better the mean fatigue life. This phenomina may
be attributed to die/package ratio, the bigger the die/package ratio, the
worse the fatigue life. However, for tape BGAs (tape substrate is much
thinner than BT substrate), the result is the opposite. With the same die
size, the larger the package, the worse the fatigue life.

Can someone explain why the difference between BT and Tape BGAs?

Best regards,


Yuan Li

------------------------------

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