Received: |
by ipc.org (Smail3.1.28.1 #2)
id m0uJqea-0000CCC; Wed, 15 May 96 19:10 CDT |
Old-Return-Path: |
|
Date: |
Wed, 15 May 96 17:01:53 PST |
From [log in to unmask] Thu May 16 13: |
37:23 1996 |
X-Loop: |
|
Resent-Sender: |
|
X-Status: |
|
Status: |
O |
X-Mailing-List: |
|
TO: |
|
Return-Path: |
<TechNet-request> |
Resent-Message-ID: |
<"7i3k71.0.faB.BAdcn"@ipc> |
Subject: |
|
From: |
|
Precedence: |
list |
Resent-From: |
|
Message-Id: |
|
Parts/Attachments: |
|
|
From a reliability standpoint, a flag is only a potential problem as a
potential shorting path, thus 2000A and ANSI/J-STD-001 would only
reject when the flag (or any other conductive element) can or does
reduces the spacing between conductive elements to less than the
design allowable elecrical spacing:
Violation of minimum design electrical spacing. This condition
includes potential movement of conductors (including conductive
part bodies, leads, wires, etc.), solder balls, excessive solder
and bridging.
Note that design electrical spacing was taken to include the "Z" axis
as well (ie. can't violate the "envelope" for the hardware). Many
people further reduce this as a "safety" item (ie. if it's big enough
to "stab" someone it should be removed.)
Jim Maguire
Boeing
______________________________ Reply Separator _________________________________
Subject: ASSY-Flagging
Author: [log in to unmask] at esdigate
Date: 5/13/96 10:43 AM
(This is a re-do of an inquiry sent Friday, in case it went nowhere. I've
received
no replies and we had a mail-server problem, so I thought I'd try again)
I've been tasked with justifying the enforcement of a long established
internal requirement, here at PBNI. For as long as I can recall, we have
been considering solder flagging (aka icicles, solder spikes) a rejectable
condition, even when a solitary occurrence of as little as 0.8 mm.
(We based this rejection upon workmanship standards that we adopted
from a sister organization with a much more Class 3 and military
orientation).
As we are manufacturing Class 2 products, and are re-evaluating the adopted
requirements, this 'reject' comes into question. I'm reviewing
ANSI/J-STD-001A
and IPC-A-610B this morning, I find no reference to this condition other
than
that shown in Figure 4-17 of the latter.
I certainly don't object to loosening up on our present standard if it is
not
justifiable, but I can't help the feeling that I'm missing something. Am I
?
An anticipatory ...Thanks !
|
|
|