You get an A plus. Perfect tense and syntax. That's exactly the response
I would have given.
Many of us were at the IPC meetings and we discussed this issue. No one
would believe it was PbCO3. Pure lead needle crystals do to stress or an
imbalance is more understandable, but still pretty amazing.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, September 13, 2006 5:23 AM
To: [log in to unmask]
Subject: Re: [TN] PbCO3
Well, I don't think you are losing it, Ioan. I have seen a lot of creeps
with whiskers in this business myself.
Dewey, this is my thesis submission for Friday 101.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan
Sent: Wednesday, September 13, 2006 7:12 AM
To: [log in to unmask]
Subject: Re: [TN] PbCO3
Inge,
I will risk myself and through in some confusion.
How did you realize you had this problem, in the first place? Are you
sure it could produce failures?
Now the slippery teritory, since it's been years since I took my
materials stress class: if I remember well, the stress class we had was
based on several hypoteses and one of them was the homogeneous material.
So the von Mise's I have studied was based on the same material all over
the place. Here you deal with one alloy for the ball, one alloy for the
top attachment and another alloy for the bottom attachment. Maybe this
alters the stress distribution?
Are the whiskers you see mono crystals? In order for you to repeatedly
get them, it is obvious you have the same stress, at the same place,
every time. Maybe you have a Sn starvation at the equator due to
migration towards the joined zones. Then you might have different stress
distributions on the various zones due to different alloys. And on top
of it, the creep. Wouldn't the whiskers a result of the creep?
If you think I am losing it, just have me recall the message.
Regards,
Ioan
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