Received: |
by ipchq.com (Smail3.1.28.1 #2)
id m0t5hFV-0000HIC; Wed, 18 Oct 95 17:46 CDT |
Encoding: |
27 Text |
Old-Return-Path: |
|
Date: |
Wed, 18 Oct 95 09:50:59 CST |
Precedence: |
list |
X-Loop: |
|
Resent-Sender: |
|
X-Status: |
|
Status: |
O |
X-Mailing-List: |
|
From [log in to unmask] Sat Apr 27 15: |
07:02 1996 |
TO: |
|
Return-Path: |
|
Resent-Message-ID: |
<"jQ3aT.0.jF3.DEOXm"@ipc> |
Subject: |
|
From: |
|
Resent-From: |
|
Message-Id: |
|
Parts/Attachments: |
|
|
I have been unable to locate a system assembly level
spec that details allowable warp and bend of an SMT
PCBA while it is being installed into a chassis of
some kind.
I have concerns of potential fractures of SMT
solder joints if the PCBA is allowed to flex "too much"
due to installation of daughtercards, I/O cards, power cords,
etc...but have no idea how much is "too much".
Based solely on flexing some out-of-date circuitry
with my bare hands, it seems evident to me that it doesn't
take much flex or bend to create an open or intermittent circuit
connection.
To give you a visual idea of the kind of flex I am looking at that
many of you may be familiar with, consider pushing the power supply
cable connectors of a PC power supply into an IBM PC Compatible
motherboard...there are generally speaking, one or several 208-pin
PQFP's in the area as well as numerous SOICs, R's and C's.
Can anyone point me toward an allowable flex spec for a PCBA in order to
eliminate the incidence of assembly and handling induced SMT joint
problems?
[log in to unmask]
|
|
|