Hi Kaye: AAHHH the infamous "hook" demon has returned. Just out of
curiosity, did an older engineer type come up with this under cured laminate
theory?
I thought it had finally gone away back in the early 80's. The term hook
comes from the signature or appearance of the phenomena when captured on an
oscilloscope. It actually dips down and then comes back up giving the
appearance of a hook.
Without giving out too many secrets I think you will find you cannot bake
hook out. We went down that road back in the 70's and 80's, used to post
bake the hell out of it. Didn't make any difference. We even specified "low
hook" laminate which never truly existed.
The phenomena and effect you are experiencing may truly be related to under
cured laminate, however hook is usually attributable to improper design as
opposed to a pure materials issue.
Regards
Michael Barmuta
Staff Engineer
Fluke Corp.
Everett WA
425-446-6076
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Kaye Clayo
Sent: Wednesday, April 27, 2005 12:53 PM
To: [log in to unmask]
Subject: Re: [TN] How to Bake FR4 Boards
Judy
From what I understand, and that is not a lot, hook is when
Er changes with frequency at low frequencies, which changes
the capacitance, which results in distortion of output signals.
If anyone has any other information about this phenomenon,
please enlighten us.
Kaye
At 03:36 PM 4/27/2005, Judy Brown wrote:
>What is a "hook problem"?
>
> Judy
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Kaye Clayo
>Sent: Wednesday, April 27, 2005 12:10 PM
>To: [log in to unmask]
>Subject: [TN] How to Bake FR4 Boards
>
>Dear Technet:
>
>Can someone tell me what temperature and duration
>we should bake some unpopulated FR4 (HASL) boards?
>
>We are attempting an experiment to see if we can "bake" a
>potential problem out of certain boards, but we don't know
>what the baking temperature / time should be. The potential
>problem we are looking to bake out is under cured laminate
>which could be causing a hook problem.
>
>Please help.
>
>Kaye
>
>
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