I agree, this part saw too much heat duration; perhaps in the press.  Kapton can become brittle exposed to air and heat.  Maybe the flex area was cut back and exposed during lamination.  If its protected (sealed in a cocoon type construction) then atmosphere does not get to the outer bare caption surface thereby slowing any oxidizing that could occur under lamination temperature.  Lamination can be 370 to 390 F.  I would look at flex fab and lamination history and method especially material against the part like Mike mentioned, e.g., Silicon press pad.

C. D. (Don) Dupriest
LM Fellow - SME-PWB/CCA Technology

Lockheed Martin Missiles and Fire Control 
Advanced Manufacturing Technology
member of: Production Technical Excellence Staff
Office: 972/603-7724
Email: [log in to unmask]

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-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Bill Ortloff
Sent: Wednesday, October 28, 2015 12:15 PM
To: [log in to unmask]
Subject: EXTERNAL: Re: [IPC-600-6012] Flex quesstion


Vicka,
You have received some good comments from several of the members. KaptonR can become brittle due to age or temperature excursions - not seen often.
Is the area with the cracks in a bend area? If yes, what is the bend radius? Can you send cross section pictures?

Regards,

William A. Ortloff
Engineering Fellow
HWEC - MSPPD
Space and Airborne Systems
Raytheon Company

310.607.7333 office
310.616.1873 fax
310-765-0381 cell
[log in to unmask]



From:	"Hammill, Vicka (EHCOE)" <[log in to unmask]>
To:	<[log in to unmask]>
Date:	10/28/2015 08:57 AM
Subject:	[IPC-600-6012] Flex quesstion
Sent by:	IPC-600-6012 <[log in to unmask]>



Has anyone ever seen this condition of cracking of the Kapton on a flexible
part of a  rigid flex?   If so, do you the cause?   We have done
crossections on this and it showed the kapton only cracking...the adhesive was not cracked and remained untouched.  So far, we have found no specific reason for the cause.
Any input would be appreciated.




Vicka Hammill
Staff Engineer/PB CAA

Honeywell
Lync Phone: 480-627-5547
FAX: 602-436-1005
[log in to unmask]<mailto:[log in to unmask]>

(See attached file: just flex front 2.jpg)

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