Hi Mumtaz,
I would have to agree that these should not be accepted for production lots,.....
BUT I know in the past, we have had to accept the product and vacuum bake bare PWBs as if for moisture content in order to support the accelerated schedule that design was under.
The product was not deliverable to customers other than internal engineering which contained the risk. The root cause was exceeding the maximum drilled holes per inch ratio in at least one of those situations.
Also, you did not mention what the yield has been with baked boards.....did it eliminate the delam entirely? We were not typically able to eliminate it (some still fell out as a result of reflow even after baking.)
Good luck,
Phil
"Stadem, Richard" <[log in to unmask]> wrote:
Mumtaz,
I agree completely with Kathy.
I would not accept them either. Why would you? The only thing to gain
would be to prevent slippage of a scheduled build, but the risks of
losing more of your component supply and having to re-order parts and
put the program farther behind is far worse. I would expect the fab
house to replace the defective pwbs (immediately), and provide something
to make up for your losses in future p.o.'s. And I would run a few
samples of the replacement bare pwbs through the reflow process ahead of
time to ensure you do not see the same problem. They can still be used
as good hardware.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kathy Kuhlow
Sent: Friday, September 16, 2005 9:31 AM
To: [log in to unmask]
Subject: Re: [TN] Rework for Delaminated PWBs
I wouldn't accept them I would reject due to the uncertainty of the PCB.
Kat
>>> [log in to unmask] 9/15/2005 8:20:30 PM >>>
Dear Technetters,
We have received a large batch of PWBs that is showing delamination
after reflow at peak temp. 230C. Laminate is high Tg - 170C.
Supplier is proposing to perform the following rework -- on these boards
instead of providing replacement parts.
Oven bake at 190C for 2.5 hours followed by second bake at 150C for 2
hours at 6kg/cm2 pressure. Will this guarantee a full cure?
I am concerned about latent failures and layers opening up as full cure
was not achieved the first time.
Any inputs from the forum will be appreciated.
I will request Steven Gregory to place the image of delamination on his
website. Have a great weekend.
Thank-you
Mumtaz
D/ 252 - SMT Process and Component Quality
Bldg. V238E
Voice (858)-882-1967
Fax (858)-882-3126
Page (858)-635-1180
Cell: (858) -449-7054
email: [log in to unmask]
Kyocera-Wireless Corp.
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