Hello Poh,

Adding of silver to eutectic paste widens the liquidus temp. and gives a
range, I believe making it somewhat non-eutectic. This "plastic range" is
what helps the tombstoning components. However, this does not fix the
original reason for the tombstoning...if there is one. Check your design,
especially pad spacing and if they can be decreased.




Jason Gregory
SMT Production Supervisor/
Integrated Product Team Leader
LaBarge Inc.
(918)459-2367
(918)459-2221 fax
[log in to unmask]
http://www.labarge.com



                      Poh Kong Hui
                      <[log in to unmask]        To:       [log in to unmask]
                      M.SG>                    cc:
                      Sent by: TechNet         Subject:  [TN] Solder Paste with 0.4% silver
                      <[log in to unmask]>


                      03/22/03 05:50 AM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to Poh
                      Kong Hui






Hi Technetters,

I understand that the 'anti-tombstone' solder paste contained 0.4% silver.
Some people told me that the melting point is 179 deg.C and other said it
was 183 deg.C.

I am wandering which is correct.

And what about the percentage for the tin & lead, whether the tin makes up
63% of the alloy & the lead consists of 1.6%, or some other number.

Thanks.

Regards,
Poh

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