Hi John,
It is gang bonded in one shot and the co-planarity is a good point - I
highly doubt that the 160 odd leads ( 40 per side) are all co-planar given
they are .0032 wide and less than .0007 thick - when I breathe on the leads
they move. Regards Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke
Sent: January-06-10 3:48 PM
To: [log in to unmask]
Subject: Re: [TN] Pull strength of thermosonic wire bondable gold
The key to this may be the terms "with no kapton support" and "ultrasonic"
being used in the same paragraph.....
Steve, are these bonded individually i.e. 1 lead at a time or gang bonded -
all at the same time. If the latter you may have to look at a different
system as coplanarity is the key and for ultrasonics, support of the
materials being joined is a critical factor at the individual bond point.
John Burke
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Fjelstad
Sent: Wednesday, January 06, 2010 9:35 AM
To: [log in to unmask]
Subject: Re: [TN] Pull strength of thermosonic wire bondable gold
Hi Steve,
Sounds a lot like TAB gang bonding.
Are you sure you even need the nickel? (or is it required elsewhere for
some reason?)
That the gold bumps are undisturbed is somewhat disturbing in its own right.
One data point from the past. The original Tessera microBGAs leads were
gold over copper bonded to aluminum pads and they worked quite reliably.
They were point bonded however.
Good luck sorting it all out...
Best,
Joe
In a message dated 1/6/2010 5:52:02 A.M. Pacific Standard Time,
[log in to unmask] writes:
Hi Steve et al,
Unfortunately this is not as easy as it sounds. First the lower pull
strengths are not necessarily a failure- they are just not as good. This
was an experiment designed between ourselves and our customer. The initial
problem is we have a .0032 wide flying lead ( about 150 of them) with no
kapton support. A chip/die is "compression bonded" onto the lead - from
what I can gather it is a combination of heat/pressure/ultrasonic and some
kind of proprietary magic. The reason we went to the lower nickel is
because the leads being so fragile they often crack during the process so
we tried the lower nickel to alleviate this issue. With the lower nickel
pull is approx.
5-7 grams. With the higher nickel 9-11 grams. There is a gold bump on the
die and when the failure happens the gold bump separates from the lead with
no damage to the gold bump. At present this is as much as I know. Thanks
for the input so far. Steve Kelly
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
Sent: January-05-10 6:14 PM
To: [log in to unmask]
Subject: Re: [TN] Pull strength of thermosonic wire bondable gold
Steve,
If you can send me the data sets in an Excel format, I can provide you with
some insight based on magnitude and grouping by Weibull plot.
If there is a big mix of failure modes, this interpretation will be pretty
generic.
Its free input, however :-)
Just send it direct.
Steve C
-----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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