>From what I recall from working with HP many years ago, the hardeners in 
gold (usually cobalt or nickel) also act as impurities.  Hence the reason to 
use soft gold for gold wire bonding, because it is purer (s/b at least 
99.99%, I think).  So, the harder the gold, the more impurity and a quick 
drop in bondability.  At the time they were doing thermosonic gold wire 
bonding and we were making the gold-plated circuit boards.  As to the 
testing, I believe much work has been done by HP, Motorola and AT&T, to name 
a few.  Hopefully you can locate someone in one of these organizations.

Patty
 ----------
From: TechNet-request
To: SMTP2; technet
Subject: NO SUBJECT
Date: Tuesday, August 06, 1996 11:40AM

From:  Stephen Ayotte
       EM Quality Engineering
       Bldg. 14-3 Col F5 5-1537
Subject:

I have a question similar to the ionics question asked last week.

Does anybody know the impact that gold hardness and impurity has
on wirebondability?

For a gold wire wedge bonder application the specification requires
gold with a Knoop hardness of 90 or less and a purity of 99.9 or
higher.  What if the hardness is greater than 90?  How high has anyone
done testing; 100, 200, 300?  Same for purity, how low a purity has
anyone done testing or had practical experience with; 99.5, 99.0, 98.0?

Thanks.

**** IBM MD Product Quality Engineer       ****
****       OEM Quality Engineer            ****
**** Interenterprise Address: USIB6CEF     ****
**** Internet Address: [log in to unmask] ****

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