Chuck,
I am not a process gal but would like to learn more. Why the smell of
ammonia when the blister is cut?
Regards,
Wee Mei
----- Original Message -----
From: "Brummer Chuck" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, October 20, 2005 2:46 AM
Subject: Re: [TN] Delamination at Thermal Via area?
> Hi,
>
> I stayed quiet before because it looked like several people had some great
> clues to your problem.
> But with these other pictures, it would appear to me that there was a
> problem with moisture or water in the lay up. If you cut a blister an
> smell
> ammonia, then there was water present when the board was laminated.
>
> Chuck Brummer
> Siemens/AIM
>
>
> -----Original Message-----
> From: Steve Gregory [mailto:[log in to unmask]]
> Sent: Wednesday, October 19, 2005 10:49 AM
> To: [log in to unmask]
> Subject: Re: [TN] Delamination at Thermal Via area?
>
>
> Hi George!
>
> Got your pictures up! Check out:
>
> http://www.stevezeva.homestead.com/files/Delamination_Blisters-1.jpg
> http://www.stevezeva.homestead.com/files/Delamination_Blisters-2.jpg
> http://www.stevezeva.homestead.com/files/Delamination_Blisters-3.jpg
>
> Kind regards,
>
> -Steve Gregory-
> Senior Process Engineer
> LaBarge Incorporated
> Tulsa, Oklahoma
> (918) 459-2285
> (918) 459-2350 FAX
>
>
>
> |---------+---------------------------->
> | | "Wenger, George |
> | | M." |
> | | <George.Wenger@an|
> | | drew.com> |
> | | |
> | | 10/19/2005 11:00 |
> | | AM |
> | | |
> |---------+---------------------------->
>
>>---------------------------------------------------------------------------
> -----------------------------------|
> |
> |
> | To: TechNet E-Mail Forum <[log in to unmask]>@SMTP@Exchange,
> Stephen R Gregory/LABARGE@LABARGE |
> | cc:
> |
> | Subject: RE: [TN] Delamination at Thermal Via area?
> |
>
>>---------------------------------------------------------------------------
> -----------------------------------|
>
>
>
> Wee Mei,
>
> I've asked Steve to post three images of delamination blistering that
> might be different than you are seeing but the cause is most likely the
> same. I do not know how many layers there are or the number of thermal
> vias there are in the heat spreader portion of the U2 footprint on your
> board but it appears that your delamination is occurring in an area of
> the board where the outside layers are totally covered by metal (i.e.,
> copper). This is decrease the ability of the board to outgas in those
> areas if the board is heated too rapidly or to too high a temperature.
> I'm also assuming but can't tell because I haven't seen a cross section
> of your thermal vias but my guess would be that you do not have good
> attachment integrity of the outer-layer copper to the barrels of the
> thermal vias and therefore the thermal vias are not providing any
> mechanical strength to hole you board together when reflowed. The three
> images I've sent to Steve show delamination blisters on the bottom side
> of a 14-Layer PCB. The delamination is occurring between layer 13 and
> layer 14 in areas that have a copper ground plane on Layer 14. There
> acre also not PTH's in these areas to hold the board together when
> internal moisture is driven off too fast. There are no blisters where
> ever there are PTH's. We're not sure there was a single cause for our
> delamination or multiple causes. These boards were over 1 year old and
> could have and probably did absorb moisture from the environment. We
> believe the reflow profile that caused these blisters had too fast a
> ramp and too hot a peak temperature. If we baked the boards prior to
> the reflow they didn't delamination or if we didn't bake the boards and
> used a correct profile they didn't blister. I hope this information
> helps you find the root cause for you delamination. My suggestion is to
> examine your reflow profile and cross section thermal vias in the
> blistered area.
>
>
> Regards,
> George
> George M. Wenger
> Reliability / FMA Engineer
> Base Station and Subsystems Group
> Andrew Corporation, 40 Technology Drive, Warren, NJ 07059 (908) 546-4531
> [log in to unmask]
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
> Sent: Wednesday, October 19, 2005 10:30 AM
> To: [log in to unmask]
> Subject: Re: [TN] Delamination at Thermal Via area?
>
> Hi Wee Mei!
>
> I've got your pictures posted. Go to:
>
> http://www.stevezeva.homestead.com/files/U2_top.JPG
> http://www.stevezeva.homestead.com/files/U2_bottom.JPG
> http://www.stevezeva.homestead.com/files/U2_delamination.JPG
>
> Are the vias filled? Are you seeing this delamination on very many
> PCB's? Are you seeing it only on the bottom of the PCB?
>
> Kind regards,
>
> -Steve Gregory-
> Senior Process Engineer
> LaBarge Incorporated
> Tulsa, Oklahoma
> (918) 459-2285
> (918) 459-2350 FAX
>
>
>
> |---------+---------------------------->
> | | Wee Mei |
> | | <[log in to unmask]
> | | SG> |
> | | Sent by: TechNet |
> | | <[log in to unmask]>|
> | | |
> | | |
> | | 10/19/2005 03:47 |
> | | AM |
> | | Please respond to|
> | | TechNet E-Mail |
> | | Forum |
> | | <[log in to unmask]>|
> | | ; Please respond |
> | | to Wee Mei |
> | | <[log in to unmask]
> | | SG> |
> | | |
> |---------+---------------------------->
>
>>-----------------------------------------------------------------------
> ---------------------------------------|
> |
> |
> | To: [log in to unmask]@SMTP@Exchange
> |
> | cc: (bcc: Stephen R Gregory/LABARGE)
> |
> | Subject: [TN] Delamination at Thermal Via area?
> |
>
>>-----------------------------------------------------------------------
> ---------------------------------------|
>
>
>
> Hello,
>
> Just asked Steve to download 3 pictures on the defects. Kindly take a
> look at them and would appreciate some feedback on the possible root
> cause.
>
> Steve : Thanks for the downloading.
>
> Regards,
> Wee Mei
>
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