Subject: | |
From: | |
Date: | Tue, 31 Oct 95 16:34:14 GMT |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
CTE FR4 laminate 14ppm/degree C Copper 17.5 from memory
Kind regards.
John Burke.
______________________________ Reply Separator _________________________________
Subject: CTE Values of Printed Circuit Board and Heatsink combination
Author: [log in to unmask] at INTERNET
Date: 10/31/95 4:54 PM
content-type:text/plain;charset=us-ascii
mime-version:1.0
Help!
The Engelmaier equations used to estimate cycles to
failure for leadless SMT components has, obviously, as
one of it's terms the CTE of the printed wiring board. I
have been unable to obtain information on CTE of printed
circuit boards, at least with any confidence, and
measuring the CTE after build is too late in the product
development cycle. This is cirtical to our applications
due to the long thermal cycling requirements of some of
our programs (7-15 years).
The CTE of the board is effected by:
Base Material (Kevlar, Polyimide, G10)
Resin
Materal Lot
Layer count
Amount of copper (planes)
Heatsink bonding
Heatsink bonding material (epoxy, acrylic, thermabond)
Heatsink material (aluminum, copper)
1. Has anyone done any testing on CTE of boards as a
function of the above?
2. Are there any equations which can be used to predict
the CTE of the board and/or heatsink combination?
3. Is there any data on the CTE of boards besides the
ranges I have seen in the text books.
I am considering running an experiment to determine the
effects of these parameters. Would anyone be interested
in the data and of course help support the effort with
boards, heatsink and bonding?
Jim Faris
AlliedSignal Aerospace
Guidance & Control Systems
(201) 393-3779
|
|
|