Hi Pascal,
From what you are saying it looks like you might be facing electrochemical migration, not electromigration. Do you see any dendrites between the leads or all damage is only inside the joints?
Regards,
Vladimir
Vladimir Igoshev, Ph. D.
Senior Materials Researcher
Research in Motion
451 Phillip St.
Waterloo, ON, N2L 3X2
Voice: (+1) 519-888-7465, ext. 5283
Fax: (+1) 519-886-0863
E-mail: [log in to unmask]
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]]On Behalf Of Pascal Guiheneuf
Sent: Friday, January 27, 2006 8:33 AM
To: [log in to unmask]
Subject: [LF] Electromigration, high density current, Lead-free
connectors
Hello,
I am looking for information around an electromigration topic : due to Lead-free, we moved, on a power connector, from a SnPb plating to a Tin (10um) plating with a Ni barrier (5um) on copper; after 700h of a 2000 hours 50°C, 7 Amps, 70°C ambient temperature, we are facing failures. RCA leads to electromigration in high current densities, accompanied with other collateral damages (Ni3Sn4 intermetallic rapidly growing, Tin particles (maybe due to excess voiding or due to fretting corrosion on Tin softened by the actual temperature), possibility of arc (voiding)..), all mechanisms leading to higher resistivity, temperature increasing, and catastrophic failure as soon as the temperature is beyond 130°C (plastic limit). For your information, we have also seen Tin Whiskers during the same experiment. The first time we succeeded in Tin Whiskering !
We would like to change to a power connector Gold plating with Ni barrier. Is anyone of you aware of anything here, relative to high current densities, to Gold electromigration, etc...? I couldn't find the data around the Black's law which defines the EM, relative to Sn or Au, and request your help.
Very cordially,
Regards,
Pascal Guihéneuf
Nortel Wireless
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