Steve and Technetters:
Adhesiveless materials (IPC-4204/11) refer to clad substrates that do
not use an adhesive layer for bonding the copper to the polyimide
substrate as was the case for legacy flex clads. The finished flex must
still have some type of "glue", such as acrylic for bonding all of the
layers and dielectrics together. Acrylics are typically used but they
have poor bond strength in high temperature environments, especially if
there is stress present such as a formed flex under bending compression.
Alternate materials such as Espanex from Nippon Steel (modified
polyimide), or Dupont's new TK flex products (Kapton(r) & Teflon(r)) may
be appropriate. Check with your flex supplier.
Bob Sheldon
Main: (714) 641-3132
Mobile: (714)745-6193
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dave Connitt
Sent: Tuesday, December 22, 2009 9:42 AM
To: [log in to unmask]
Subject: Re: [TN] Via fill on flex
Steve,
Have you considered a adhesiveless material such as Dupont PARALUX. I
think the part number is AP9121 but I could be wrong. The IPC
specification is IPC-4101b/41. By the way, it's Tg is about +250
Celsius. By the way, I think you are answering you own question
regarding exceeding the Tg of the material and seeing failed vias as a
result..
Dave Connitt
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Kelly
Sent: Tuesday, December 22, 2009 11:26 AM
To: [log in to unmask]
Subject: [TN] Via fill on flex
Hi All,
We have a 6 layer flex that my customer has to thermal cycle at
temperatures beyond the rated Tg's of the material- the end use
environment is about as bad as it gets. After repeated thermal cycles we
start to see cracks develop in the glue layer used to bond the
adhesiveless layers together. Will some kind of via fill help this
issue?
Thanks in advance.
Regards Steve Kelly
Steve Kelly (PLEASE NOTE NEW E-MAIL ADDRESS)
(416) 750-8433 (work)
(416) 750-0016 (fax)
(416) 577-8433 (cell)
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