Hi Earl,
have to second your thoughts on that one. Either I missed something (must
have been some power nap during the lesson) or it wasnīt known at that time
when I took ym courses.
Was just checking with our "solder slaves" just having attended a solder
course according to MIL- and ESA-standard and that wasnīt in there as well.
So, I do not doubt that you got no wetting with IMCīs but it seems that we
havenīt managed to get down to it with our methods or havenīt noticed it
cause the spots of IMC at the surface were that tiny that wetting around
those spots looked good enough for us but still lead to "weaker?" joints
after rework.
But I have to admit that in some rare cases when wetting wasnīt possible for
what reason ever we worked our way through the material until we met some
virgin copper, et violá, soldered to that.
Who knows? , we just believed that it should be done the way they teached us
and we teached others. The whole "dilemma" we are in is that we canīt check
the joints after weīve done our work without destroying them to see what
really happend so we have to trust our methods. If not we would die sooner
or later of "permanent doubt stress" or bad conscience regarding our work.
Have a good time ... and .. hmmmh ... donīt ge too confused about Bevīs
gender changing mentality ;-)
Wolfgang
-----Ursprüngliche Nachricht-----
Von: Earl Moon [mailto:[log in to unmask]]
Gesendet am: Mittwoch, 24. Oktober 2001 12:21
An: [log in to unmask]
Betreff: Re: [TN] Antw: [TN] exposing intermetallic on BGA pads...
Guenter,
I cannot believe how much I am learning every minute about soldering and all
comprising it. Not at all being negative or contrary, I must have ruined
thousands of solder joints in my long life in this business notwithstanding
all the rework I've done and taught others.
All I've ever been taught, done, and taught others is to remove the solder,
with whatever means that works without damaging pads or board materials,
then print paste, place components, and reflow.
I've never even heard of leaving on solder or removing intermetallics -
especially with a glass brush. I finished my last contract, seemingly
successfully, two months ago. Can the world and all its "wonderful"
soldering technology all of a sudden be passing me by in such a short time?
Jeez, a glass brush. Thanks again Guenter, but I must need more help than
even you, Bob Willis, or all other experts can give.
Earl
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