Steve,
Again I was not explicit. Yes, of course I was not referring to the part
being taken off (it is tossed) or the part being put down (agree with
what you do). I am concerned about adjacent MSL parts.
How do you know that AL foil is good enough? How high do you let those
other thermocouples get?
Bev
RIM
-----Original Message-----
From: Steve Gregory [mailto:[log in to unmask]]
Sent: January 18, 2007 8:45 AM
To: TechNet E-Mail Forum; Bev Christian
Subject: RE: [TN] Rework of circuit packs with MSL Parts
Mornin' Bev,
Most of the time the only time I'll dry (bake) a board before rework is
when the board is polyimide. I'm not usually worried about the component
because the one on the board is being replaced by a new one, and if the
new one is a MSD, it either has been kept in a dry cabinent if the
package has been opened or the package has been sealed. If I question
whether or not it has been exposed, I will dry it before rework.
The rework station I'm used to working with monitors temperature of the
part being reworked and PCB temperature adjacent to the rework area in
real-time during the rework cycle with non-contact thermocouples. If I'm
concerned about any part adjacent to the part being reworked, I simply
take a piece of aluminum foil and sheild the part. The rework station
uses IR light, so it's very easy to do...
Steve Gregory
(Trying to thaw out from all the ice we've had here lately)
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: Thursday, January 18, 2007 7:23 AM
To: [log in to unmask]
Subject: [TN] Rework of circuit packs with MSL Parts
Technetters,
We have required that circuit packs that are going to be reworked to be
dried before rework. My questions to all of you are:
1) Do you require this for all your boards irrespective of what is on
them?
2) Do you dry it to the requirements of the most sensitive MSL
component?
3) Do you use thermocouples to see how hot the MSL components are going
to get from radiated, convected and transmitted heat?
40 If the latter, what is the maximum temperature you allow the nearest
MSL component to reach before you require a pre-dry?
Thanks in advance.
Bev
RIM
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