To ALL TECHNETER:
I made a mistake in the note below. The SIR readings should have
been 10 to the eleventh (and not minus 11th) and 10 to the
seventh (and not the minus 7th). Sorry about that. It's been a
long day.
Harry
______________________________ Reply Separator _________________________________
Subject: Re[2]: Mild humor: RE: Walmart Supplies
Author: [log in to unmask] (HOHALLOR) at INET
Date: 9/26/96 1:59 PM
Paul:
You are correct. The wetting agents and the surfactants are
non-ionic materials which are not detected by the Omegameter or
the Ionigraph which only measures the concentration of the ionic
materials which are soluble in the alcohol water solution.
However, these non-ionic residues have a tendency to attract and
absorb water onto the surface of the PWB. As the water is
absorbed it is polarized. When a voltage deferential is applied
across two adjacent traces the water ionizes forming a plating
situation and dendritic growth occurs and eventually a short will
develop. So, even though your PWB appears clean according to the
Omegameter or the Ionigraph, it is actually a potential problem
when it gets to the field.
(The differences I saw between boards cleaned by cascade and
those cleaned by other methods ranged from 10 to the minus 11th
ohms for others to below 10 to the minus 7th ohms for the cascade
cleaned boards. This was at 35 degrees C and 85% RH.)
Harry
______________________________ Reply Separator _________________________________
Subject: Re: Mild humor: RE: Walmart Supplies
Author: [log in to unmask] at INET
Date: 9/26/96 10:55 AM
Man, and here I thought I heard some weird ones! Great List - it went into
my oddities file. Thanks.
<< By the way, just what surface insulation resistance would one get on a
board which
was washed in Cascade after hot air solder level? I've understood it had
been
tested and found it "passed" the "Omegameter" test. Does that mean better
than
60%? >>
In almost all cases, the SIR gets shot all to hell. An additional 2-3
decades drop due to the cascade. The cause is surfactant and wetting agents
which do not register on an Omegameter. Harry O'Halloran also replied to my
comment indicating he had seen drops like this.
Doug.
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to: *
* [log in to unmask] with <subject: unsubscribe> and no text. *
***************************************************************************
Received: from camelot.dsccc.com by inet.dsccc.com with SMTP
(IMA Internet Exchange 2.02 Enterprise) id 24AB2DB0; Thu, 26 Sep 96 11:44:11
-0500
Received: from offramp.dsccc.com (onramp.dsccc.com [192.1.1.139]) by
camelot.dsccc.com (8.6.11/8.6.10) with SMTP id KAA25228; Thu, 26 Sep 1996
10:10:33 -0500
Received: by offramp.dsccc.com (5.67b/SMI-V1.8)
id AA07703; Thu, 26 Sep 1996 10:11:26 -0500
Received: from ipc.org(168.113.24.64) by offramp via smap (V1.3mjr)
id sma007642; Thu Sep 26 10:10:49 1996
Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI)
id KAA04506; Thu, 26 Sep 1996 10:01:32 -0700
Resent-Date: Thu, 26 Sep 1996 10:01:32 -0700
Received: by ipc.org (Smail3.1.28.1 #2)
id m0v6HiR-0000RdC; Thu, 26 Sep 96 09:47 CDT
Resent-Sender: [log in to unmask]
Old-Return-Path: <[log in to unmask]>
From: [log in to unmask]
Date: Thu, 26 Sep 1996 10:55:43 -0400
Message-Id: <[log in to unmask]>
To: [log in to unmask]
Subject: Re: Mild humor: RE: Walmart Supplies
Resent-Message-Id: <"vTqzF2.0.WeJ.bTfIo"@ipc>
Resent-From: [log in to unmask]
X-Mailing-List: <[log in to unmask]> archive/latest/6484
X-Loop: [log in to unmask]
Precedence: list
Resent-Sender: [log in to unmask]
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to: *
* [log in to unmask] with <subject: unsubscribe> and no text. *
***************************************************************************
Received: from camelot.dsccc.com by inet.dsccc.com with SMTP
(IMA Internet Exchange 2.02 Enterprise) id 24AE87F0; Thu, 26 Sep 96 15:33:04
-0500
Received: from offramp.dsccc.com (onramp.dsccc.com [192.1.1.139]) by
camelot.dsccc.com (8.6.11/8.6.10) with SMTP id PAA10767; Thu, 26 Sep 1996
15:23:22 -0500
Received: by offramp.dsccc.com (5.67b/SMI-V1.8)
id AA25763; Thu, 26 Sep 1996 15:24:10 -0500
Received: from ipc.org(168.113.24.64) by offramp via smap (V1.3mjr)
id sma025658; Thu Sep 26 15:23:26 1996
Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI)
id PAA06198; Thu, 26 Sep 1996 15:13:16 -0700
Resent-Date: Thu, 26 Sep 1996 15:13:16 -0700
Received: by ipc.org (Smail3.1.28.1 #2)
id m0v6Lap-0000TYC; Thu, 26 Sep 96 13:55 CDT
Resent-Sender: [log in to unmask]
Old-Return-Path: <[log in to unmask]>
Date: Thu, 26 Sep 1996 13:59:22 -0500
Message-Id: <[log in to unmask]>
From: [log in to unmask] (HOHALLOR)
To: [log in to unmask], [log in to unmask]
Subject: Re[2]: Mild humor: RE: Walmart Supplies
Resent-Message-Id: <"DOLN42.0.bhM.T6jIo"@ipc>
Resent-From: [log in to unmask]
X-Mailing-List: <[log in to unmask]> archive/latest/6499
X-Loop: [log in to unmask]
Precedence: list
Resent-Sender: [log in to unmask]
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to: *
* [log in to unmask] with <subject: unsubscribe> and no text. *
***************************************************************************
|
