Ioan,
I've got a few suggestions for you to check with respect to
your process. Cold solder joints can be caused by incorrect solder
temperature, solder contamination, low preheat temperature, incorrect
conveyor speed and/or vibration and removing the board too early from the
wave. A couple of other items to check are board and component
contamination.
Best of luck,
Derek Humble
S.C. Process Engineering
Brock Telecom Ltd.
Tel. :(613) 498-3856 ext. 2428
Fax :(613) 498-3645
E-mail: [log in to unmask]
-----Original Message-----
From: Tempea, Ioan
[SMTP:[log in to unmask]]
Sent: October 4, 1999 4:46 PM
To: [log in to unmask]
Subject: [TN] Cold solder
Hi Technos,
I'm in big trouble with a backplane.
It's a 13.5"x19.5", 3.7mm thick. The connectors are
disposed in parallel
lines, forming two columns a the two extremities. In
the middle we have no
components. In between the connectors there are some
TH caps and resistors.
______________________________
______ ______ I
______ ______ I
______ ______ I
______ ______ I
.. ..
..
______ ______ I
_______________________________ I
For a long time the soldering was OK, with small
problems in the four
corners ( a couple of holes not 100% full).
For about a week or so, the solder joints of many
caps or resistors present
cold solder. There are no significant cold solder
problems with the
connectors, which present though a little less
wetting (some of the fillets
are not what they used to be).
The question is: why do I get the cold solder and
how can I get read of it?
We use :
- no-clean technology
- Multicore Sn63 solder
- Multicore X33 flux
- strong radiation preheating ( two top preheaters
at 700F and two bottom at
750F); we spent a lot of time tweaking to avoid
damaging the board
- two passes, one for fluxing only, no wave, the
second one right after with
no fluxing, but with wave
- no chip wave (that's what I have, hehehe), just
omega on our Electrovert
Econopak II
Any help would be greatly appreciated.
Thanks, Ioan
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