It's Monday morning and my head is....etc.
I'm cleaning my TechNet mails a number of months back. Found a mail from Fluke that is possibly of interest for warpagers. I got this from Fluke just when we had a w. problem, and Fluke's advice came in right time. Of course, not a general problem solver equation, anyway, hope it adds something to someone.
Regards
Ingemar Hernefjord
Ericsson Microwave Systems
DEWARP PROCEDURE
De-warping shall be accomplished using the Press Area oven as the
primary tool. If it is
unavailable, the Screening Area oven may be used as a backup.
All de-warping must be coordinated with the Press Area operators to
ensure that press
schedule is not compromised. If there is a conflict of order priority,
the final decision will be
made by the Process Owner.
STACKUP PANELS
Place the Oven Shelves no lower than the 4th slot from the bottom to
prevent them from
coming too close to the heating elements.
Stack panels to be de-warped (maximum 4 high), using the following
configuration.
DO NOT PLACE ANY WEIGHT ON TOP OF STACK!
BAKE THE STACKUP
If using Press Area oven, preheat to 325°F.
If using Screening Area oven, preheat and verify oven setting of 300°F.
Place stack-up inside preheated oven.
Bake for (4) hours.
After (4) hours, shut down oven.
Allow panels to cool slowly inside oven with doors closed, to below
120°F. before removing
them from the oven. IT IS EXTREMELY IMPORTANT THAT PANELS COOL SLOWLY!
Remove panels from oven.
RE-MEASURE FOR BOW AND TWIST
Re-measure for Bow and Twist using the criteria in the previous
instructions.
Fill out a Discrepancy Report to MRB any panels that do not meet the bow
and twist
criteria.
Complete the Log Sheet and indicate how many panels were MRB (scrapped)
AFTER
de-warping.
MARKING DEWARPED PANELS THAT HAVE MET THE CRITERIA
Using an electric engraver, scribe a ¼" letter "W" within a ½ inch of
one of the
auto-insertion holes (not slots) on the carrier frame.
Mark the letter "W: on the Circuit 1 side only.
Do not make any marks on the actual PCB (part). Mark the carriers, only.
Fred J. Paul, Staff Engineer, PCB Operations
FLUKE Corporation, P.O. Box 9090, Everett, WA 98206
VOICE: 425 356 5734 FAX: 425 356 6070, [log in to unmask]
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