You can check to see if the boards are actually under cured by perform Tg
analysis. Check for double pecks. I would be hesitant in accepting these
parts. If your supplier has a chart recorder on their press ask them for a
copy to see time at temperature and pressure. I would ask for replacement
and make sure that you check the date code so you can make sure that they do
not send you back the same boards.


Scott B. Westheimer
----- Original Message -----
From: "Steve Gregory" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, September 16, 2005 7:16 AM
Subject: Re: [TN] Rework for Delaminated PWBs


> Mornin' Everybody!
>
> I have the pictures that Mumtaz sent me posted now. Go to:
>
> http://www.stevezeva.homestead.com  and click on "Picture Page 2"
> and look at; "Blister 1, Blister 2, After Bake 1, and After Bake 2".
>
> Boy, that's some SERIOUS delamination! I don't know enough to say
> if the rework that your supplier is proposing is acceptable, but my first
> question would be is why would they send you boards that are not cured?
>
> If they sent you boards that are that undercured, what else is wrong with
> these boards?
>
> I would have a very hard time accepting these boards. Which brings up
> another question, if you say you won't accept them and that you want new
> boards, how will you know that you won't get the same boards that your
> supplier has "reworked"?
>
> Kind regards,
>
> -Steve Gregory-
> Senior Process Engineer
> LaBarge Incorporated
> Tulsa, Oklahoma
> (918) 459-2285
> (918) 459-2350 FAX
>
>
>
>
>                      Mumtaz Bora
>                      <mbora@KYOCERA-WI        To:
> [log in to unmask]@SMTP@Exchange
>                      RELESS.COM>              cc:       (bcc: Stephen R
> Gregory/LABARGE)
>                      Sent by: TechNet         Subject:  [TN] Rework for
> Delaminated PWBs
>                      <[log in to unmask]>
>
>
>                      09/15/2005 08:20
>                      PM
>                      Please respond to
>                      TechNet E-Mail
>                      Forum
>                      <[log in to unmask]>
>                      ; Please respond
>                      to Mumtaz Bora
>                      <mbora@KYOCERA-WI
>                      RELESS.COM>
>
>
>
>
>
> 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.
> 10300, Campus Point Drive
>
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