20 micron inches is a bit thick. E-less gold usually is used sometimes as seed layer prior to electrolytic plating. Someone may try to cover the e-less gold because they changed from aluminum bond to gold wire bonding (wedge to thermosonic). My not educated guess.
jk
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
Sent: Wednesday, March 31, 2010 7:56 PM
To: [log in to unmask]
Subject: Re: [TN] Wire bondable gold
Steve,
It is possible that the underlying electroless gold [many times harder than
#%$! and generally not bondable for TS gold ...... I know, I may take some
heat for that comment] is there for a wiping contact application.
Being quite hard [generally], the electroless holds up well beneath the soft
gold. The soft gold may even act as a 'lubricant' for a limited number of
matings.
Meanwhile, everywhere else it is wire bondable!
50µin of pure soft gold is a bonder [persons] ultimate dream surface!
Gold embrittlement of solder joints ... well, that's a whole other story..
Steve Creswick
http://www.linkedin.com/in/stevencreswick
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Kelly
Sent: Wednesday, March 31, 2010 3:20 PM
To: [log in to unmask]
Subject: [TN] Wire bondable gold
Hi all,
Anyone know a reason why a customer would call up 20 micro inches of
electroless gold followed by 50 micro inches of electroplated soft gold for
thermosonic gold wire bonding? Is there an advantage to having the
electroless underneath?
Regards Steve Kelly
PFC_2col.png
CREATING A FLEXIBLE FUTURE
Steve Kelly
(416) 750-8433 (work)
(416) 750-0016 (fax)
(416) 577-8433 (cell)
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