Ingemar,

Good morning!

I was thinking more of any long term reliability issues associated with the higher than normal Be contant rather than shelf life/aging concerns.  I am with you - my 'field aging studies' are very good, but none of them include wire having >4PPM Be   :-(

The aging study (was in George Harman's book) was all that I could find that mentioned 'elevated' Be contents.

Thanks for the lead.  Will check out.


  .... and tomatoes are good for us!!

Steve Creswick - Gentex Corporation
A Smarter Vison



-----Original Message-----
From: Ingemar Hernefjord (KC/EMW)
[mailto:[log in to unmask]]
Sent: Monday, August 04, 2003 3:11 AM
To: 'TechNet E-Mail Forum.'; Creswick, Steven
Subject: RE: [TN] Persons with wire bonding experience



Steve, I would contact a good metalurgist. 'Aging' is a question of chemical or  physical changes, slow or fast reactions.Oftenly resulting in crystalographic changes which have an impact on the ductility, which I believe is what you are asking for. As far as I understand, a lot is possible to calculate. Why not ask Andrew Niblett at duPont, Bristol, UK ? He's got bondwires on his brain.
His adress is: [log in to unmask]
My two pesetas
Ingemar Hernefjord
PS. We treat all bondwires like tomatoes, have to be consumed quickly. Field 'aging': no negative reports last three decades. 

-----Original Message-----
From: Creswick, Steven [mailto:[log in to unmask]]
Sent: den 1 augusti 2003 21:50
To: [log in to unmask]
Subject: [TN] Persons with wire bonding experience


All,

Here it is late in the day on Friday, and a surprise pops up.

For many, many years, I have been bonding and keeping tabs on the properties of the wire we have used. 

As with most people, I have been using Be doped wire.  In all cases it has been in the 4-6 PPM range (based on analysis of the wire, not the label on the blister pack - which usually just parots what we put on the procurement specification).

Bottom line is that the most recent melt is running at nearly 8 PPM (7.9).

This places me out of range with any 'history' that I might have.  I have seen reports on Aging & Shelf Life Stability testing, probably in one of George Harman's books.  Bottom line was that after 2 years, with <10 PPM Be, no significant change was noted in tensile strength or % elongation.  However, this was an old study, and a lot of things have changed since then, with respect to wire manufacture.

Quicky testing of a large number of wires and parts does not reveal any anomalies, but .... I am wondering if something will hit me up along the back-side of my head at a later date.  Environmental testing would take too long to be of much use in the immediate situation.

Anyone out there have any comments with respect to deleterious effects of Be doping in the ~8 PPM range??
Think of non-hermetic packaging, automotove application, high rel.

I am inclined to say no-thanks to this particular wire.

Steven Creswick - Gentex Corporation
A Smarter Vision

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