Wade,
I have not worked specifically with NEC's TBGA. Most TBGA's use Sn63/Pb37
solder balls.  Although it is common for some manufacturers to use silver
Bearing solder balls.  These are typically Sn62/Pb36/Ag2.  The silver
increases the yield strength and the electrical properties.  It is also said
to inctease the surface tension which helps in the self-alignment
characteristics. The high lead solderballs are used on ceramic devices and
some TBGAs with heat sinks or other heavy design features.  In nearly all
cases the high lead solder balls (Pb90/Sn10) as you described are attached
with Sn63/Pb37 or Sn62/Pb36/Ag2.  So you should be able to see a distinct
"joint" between the high lead ball and the package.

Hope this helps

Regards, Russ Winslow

Six Sigma
1940 Concourse Drive
San Jose, CA  95131

[log in to unmask]
http://www.sixsigmaservices.com


 -----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Wade Oberle
Sent: Thursday, February 11, 1999 8:29 AM
To: [log in to unmask]
Subject: [TN] Solder Composition for TBGA


Dear Technetters,
        This may seem like a silly question to some of the veteran
BGAers but here goes.  I have a TBGA from NEC that I need to place.  DO
all TBGAs use alloy 10Sn and 90 Pb for the solder balls or could they
use other alloys such as 63/37?  I will leave a similar message on the
NEC website and let you know the final answer.  I viewed the online spec
for this part number and there is no mention of the solder alloy.  This
makes me think it is an 'understood' industry standard that the alloy is
10/90.

Regards,

Wade Oberle
[log in to unmask]

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