Hi inge,



There are no pictures :-)



Regards,



Vladimir



AMD



-----Original Message-----

From: TechNet

To: [log in to unmask]

Sent: Fri May 04 13:21:47 2007

Subject: [TN] Metalurgists, need assistance



Have an issue with (randomly) lifted FPGA leads.

Pic 1: good joint after pull test

Pic 2: ditto but high magnification

Pic 3: "rotten" joint after pull test

Pic 4: ditto but high magnification

Pic 5: "rotten" cross section

Pic 6: ditto but high magnification



60Sn on ENIG, obviously a brittle region. Suspect Kirkendall voids, but

the pockets with zillions of Tin spheres (0.1 to 2 um in size) points at

insufficient peak temperature to make 100% melt and good solidifying. If

these little balls were Lead, I could understand, but they are Tin!

Never seen like. Any "quickhead" out there, need fast advice. 



Note: Pic 2, you can see the underlying board pad nickel as dark areas. 

An experienced analyst will hopefully recognize. No Phosphorous peaks!



My Friday headache.



Inge



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