Let me add a bit more information on this issue.
1. The material we are having issues with is Iteq IT-158. We are
not seeing any issues with any of the other laminates we are using such
as Grace MTC-97. The Iteq material has higher Tg, Td and pull
strength per specification than the Grace MTC-97 material.
2. The pad layout is identical across the product line. This
includes the distance to the edge of the panel. The pads that are
lifting are on the outside of the laminate. No internal
delaminations have been seen in the cross sections I have made. Internal
delamination si not suspected because the product operates when it is
connected back together.
3. The reflow profile is for Pb-free soldering using SAC305 solder.
The peak temperatures, duration of the temperature and time above
liquidus is the same on all reflow profiles of similar products.
So I don't think the design is at fault, nor the processing at the
assembly house. The pads are for 8-pin RJ-45 jacks using a standard
pattern.
I am seeing a ring of cleared copper on the PWB side of the pulled pad.
This is troubling me because I can think of no reason it should be there
unless the etchant was able to get beneath the copper pad. I can post
an image if someone will be so good as to point me to the picture upload
page. (much appreciated).
mark
Mark Woolley |PTRL Laboratory | Avaya | 1300 West 120th Ave |
Westminster, CO 80234 USA |
Voice (Lab): (303) 538-2166 | email: [log in to unmask] |
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Thursday, January 12, 2012 12:59 PM
To: [log in to unmask]
Subject: Re: [TN] FW: New Question on PWB Analysis
How about copper foil treated side tooth size? Tooth size hampered
high speed frequency switching signals.
Victor,
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Thursday, January 12, 2012 1:36 PM
To: [log in to unmask]
Subject: Re: [TN] FW: New Question on PWB Analysis
Regardless of the "temptations" involved (and to educate the uninformed)
What factors contribute to lower copper peel strength?
I haven't heard much discussion of that,
and I don't think my trusty ol' Printed Circuits Handbook addresses it.
(well actually, it discusses TESTING of peel strength in 8.8-8.11,
and peel strength values, but not cause).
I would probably suspect bare board issues too,
unless you can enlighten me...
Jack (aka "the new guy")
.
On Thu, 12 Jan 2012 08:41:02 -0800, Dwight Mattix <[log in to unmask]>
wrote:
>"A good PWB will normally fail within the laminate material. "
>
>That's a pretty broad statement. I wouldn't take that bet personally.
>
>It's tempting as an OEM for failure investigation to begin with the
>premise that responsibility lies with any or all inputs except the
>design, assembly process. Yep'r, don't keep no mirrors around here to
look in.
>
>
>At 07:59 AM 1/12/2012, Woolley, Mark D. (Mark) wrote:
>>
>>
>>I am in the middle of an issue concerning a high temperature Laminate
>>and low pull force copper pads. The copper can be pulled from the PWB
>>with low pull forces and are failing in the field.
>>
>>I have examined multiple damaged PWBs and have found that in ALL cases
>>the damage is the failure of the copper to epoxy bond. A good PWB
will
>>normally fail within the laminate material.
>>
>>The units are built using Pb-free processes with Pb-free components.
I
>>am trying to determine what can be done to show that the laminate is
not
>>good or in the PWB manufacturer did not laminage the layers correctly.
>>I do not have easy access to bare PWBs that have not been processed.
>>
>>
>>
>>Any help or direction would be welcomed.
>>
>>
>>
>>Thanks,
>>
>>Mark
>>
>>mark
>>
>>Mark Woolley |PTRL Laboratory | Avaya | 1300 West 120th Ave |
>>Westminster, CO 80234 USA |
>>
>>Voice (Lab): (303) 538-2166 | email: [log in to unmask] |
>>
>>
>>
>>
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