Steve,

If you can provide some of the info that others have suggested, it would
help us greatly in giving you some suggestions.  

You really want to think of failure magnitude and the corresponding failure
mode before drawing any conclusions ....  Wire break vs neck/heel breaks vs
bond lifts, etc.  If bond lifts, is the gold coming up down to the Ni?
Ouch, but it provides a clue as to the cause of the problem

Type of bonding employed and bonding conditions are another bit of info that
I would need.  You are either thermosonic ball bonding, or thermosonic wedge
bonding.  Your heat column temp is ....?  We will assume that the clamping
used for both is the same.

What were the state of the samples?  Virgin, right out of the box?  Plasma
cleaned?  Were they subjected to any temperature extremes before bonding?
If you have subjected them to reflow temps the 40µinch Ni will show up worse
and bondability will get even worse with time.  

As Joyce indicated, all plating is NOT the same, but if ONE house did them
both, that is about as good as you can get.  At least they BOTH should be
equally bondable [or not bondable], if you catch my drift.

Be glad to help out further when you can get us some additional info

Steve Creswick


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Kelly
Sent: Tuesday, January 05, 2010 4:17 PM
To: [log in to unmask]
Subject: [TN] Pull strength of thermosonic wire bondable gold

Hi All,

I have a wire bond question to the wire bond gurus who have helped me out a
lot in the past. Made 2 versions of a flex circuit - only varied the nickel
thickness. Application is thermosonic gold wire bonding.

Flex circuit lead is .0032 wide - version 1 - nickel is 150 microinches -
soft gold is 50 microinches- pull strength is X

                                                        Version 2 - nickel
is 40 microinches - soft gold is 50 microinches - pull strength is approx.
½X  of version 1-

Is this what I should expect?



Regards Steve Kelly



Steve Kelly (PLEASE NOTE NEW E-MAIL ADDRESS)

(416) 750-8433 (work)

(416) 750-0016 (fax)

(416) 577-8433 (cell)




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