Joe,
I now have some more information.
Wave soldered using Alpha RF800 flux.
Hand soldered using Kester 245 core.
Under the microscope I could see some flux residue on the pins. And I
had a good board.
The CM says they have not changed their process.
I just tried a one board experiment using Chemtronics Flux-Off and the
connectors look great.
Now into battle with the info and have the boards professionally washed.
No soldering allowed!
Phil
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Russeau
Sent: Thursday, November 15, 2007 1:49 PM
To: [log in to unmask]
Subject: Re: [TN] no-clean flux residue on connector pins
Hello Phil,
Before I became to concerned with trying to switch soldering materials.
I
would first try to identify how this problem occurred. Is this a new CM
or
a group with whom you have some history? Is this a new product for you,
for
your CM or something they have produced for awhile? Are the materials
that
were used the traditional materials for manufacturing the product or
were
they trying something new? The point that I'm trying to make is that
you
want to identify a root cause. If this product has been manufactured for
a
long time using the same soldering materials with little to no product
issues, then I don't know that switching materials will eliminate the
problem. It could also be a process related issue. As for specifying
what
processes your CM should use, yes you should do that once you identified
the
problem and how to correct it. Don't just make a recommendation before
you
have an understanding of the cause.
I would also look into cleaning the parts instead of reworking them,
especially if you know that the no clean flux residue is the cause of
the
problem. It may be that cleaning them would remove the problem.
Contacting
someone like Kyzen or Zestron would be advantageous for determining if
the
boards could be cleaned. If you are not able to clean at your facility,
I
know Kyzen will do the cleaning for you. Zestron may also have such
services. What I would suggest is that you send a few boards to your
preferred cleaning company, let them clean them, have them returned and
determine if they work. If so, have them clean the rest. Meanwhile
figure
out what your CM did differently (assuming this product has been around
for
sometime).
Best Regards,
Joe Russeau
Precision Analytical Laboratory, Inc.
----- Original Message -----
From: "Phil Nutting" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, November 15, 2007 12:50 PM
Subject: [TN] no-clean flux residue on connector pins
Good afternoon,
A problem has cropped up with a board built by a CM. The board was
soldered using a no-clean flux (I don't know which one yet) and
apparently it got on the fine pitch pins of a micro D-Sub rendering the
board non-functional because of the insulative layer of flux on some or
all pins.
So if you are sending a board to a CM;
do you specify the method of cleaning the board?
do you specify parts that must be clean after the build?
if no-clean is used, but you require a clean board to a specific IPC
level, isn't it better to use an OA or RMA washable flux?
Replacing these connectors my be more costly than simply trashing the
boards due to the time to remove and replace the connectors not to
mention the possible reliability issues. I believe the only feasible
method of removing this connector is with a selective soldering system
so all 64 pins can be unsoldered at the same time. Don't have one of
these systems.
Assuming I can find out what flux was used is there a way to clean these
connectors successfully? Sounds like a call to Zestron.
Thanks in advance.
Phil Nutting
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