Well ; this time I'd not agree Inge, feels more like a process than board .
Didn't see non wetted coupons grainy yet .
Ioan, ignore the wiseguy's teasings (typical technocrat),
and describe the process step by step please , and what's used (flux ,
alloys, temps, inertia [size of thermal dissipations = all joints grainy or
some only ?], etc.)
if it's getting worse you did not kill it yet = far from epilogue .
So far the descriptions are not sufficient to picture much .
This one I have to give to Steve ; when he mails his digital superesolutions
'm over the moon .
So unless you plan thousands words ; picture and process would be optimal .
To grainy joints there is usually simple answer ; as long as the cause is
found .
paul klasek
ResMed
-----Original Message-----
From: Ingemar Hernefjord (EMW)
[mailto:[log in to unmask]]
Sent: Wednesday, 6 October 1999 22:48
To: [log in to unmask]
Subject: Re: [TN] Cold solder epilogue... maybe
Interesting, Juan...
by the way, did you make the wetting test? I'm curious.
And what's wrong with tea, you need sip something besides the green
Chartreuse.
See you Huan..
Ingemar
-----------------------------------separator--------------------------------
Thanks for the interest and thoughtfulness.
There are three things I would like to clarify:
- first, my identity, the name is IOAN, starts with an I, the letter after
H. Some of you passed this test;
- second: tea, grog, etc is not exactly my kind of stuff; where I come from
we go for strong licors;
- third: looks like the hours I spend reading through e-mails are very
precious. Being in contact with people of your expertise is a big chance for
me.
So, after getting some of the hints on the Technet, I realized that, indeed,
it's not cold solder, but the dull, grainy joints that IPC-610 accepts for
this kind of boards.
Did this solve my problem? Maybe. Now I have this phenomenon labeled as
process indicator by the QA. This adds to the other process indicator, the
solder joints that don't have 100% filling. The same IPC-610 accepts 50%, so
we are going to make some cross sectioning.
The thing is I have two process indicators that are getting worse. More
grainy joints, more not-so full joints. I wonder where will this lead.
Why do we do two passes? We couldn't avoid damaging the board with only one
pass, simply, the board wouldn't preheat enough to avoid the thermal shock
when hitting the wave. If we set the preheaters higher, the passive
components will go out of spec.
Thanks again,
Ioan
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