Yep, they're buried vias and I think they're filled with resin. If they weren't filled they would look darker and the copper plating in the hole would look a lot rougher from the grinding & polishing.
I think the hole fill was a separate operation (there's not enough pre-preg each side to fill the hole with resin). All the delam is on one side only, maybe there was some contamination of the layer during the filling.
Geoff Layhe
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Gregory
Sent: Friday, September 16, 2005 1:50 PM
To: [log in to unmask]
Subject: Re: [TN] Rework for Delaminated PWBs
After looking at the pictures again, I'm going to ask a couple of dumb
questions...
The vias in the pictures are considered blind and buried vias, right?
Should they be filled? They don't appear to be. Could the expansion of the
air inside
the unfilled blind and buried vias during reflow be a contributor to the
delamination?
Kind regards,
-Steve Gregory-
Senior Process Engineer
LaBarge Incorporated
Tulsa, Oklahoma
(918) 459-2285
(918) 459-2350 FAX
Stephen R Gregory
(Tulsa) To: TechNet E-Mail Forum <[log in to unmask]>@SMTP@Exchange, Mumtaz Bora
<[log in to unmask]>@SMTP@Exchange
09/16/2005 06:16 cc: [log in to unmask]
AM Subject: Re: [TN] Rework for Delaminated PWBs(Document link: Stephen R Gregory)
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|
| | RELESS.COM> |
| | Sent by: TechNet |
| | <[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> |
| | |
|---------+---------------------------->
>--------------------------------------------------------------------------------------------------------------|
| |
| To: [log in to unmask]@SMTP@Exchange |
| cc: (bcc: Stephen R Gregory/LABARGE) |
| Subject: [TN] Rework for Delaminated PWBs |
>--------------------------------------------------------------------------------------------------------------|
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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