RE>Lead bond peel strength 11/6/96
Rick,
Here are a couple of things that you could consider. (In a past life, our group did this kind of testing and analysis for many years.)
1) It is extremely difficult to do a joint by joint comparison. There are too many factors which will affect your joint strengths (lead/pad registration, skew, coplanarity, solderability, solder paste volume, etc). Rather, we found that it was easier to look at entire populations. Make sure that you get a very good statististical sampling - a confidence level of 90% or greater is recommended.
2) Look at your device prep procedure and make sure that you aren't inducing any artificial effects. I'm assuming that you're excising the package body following reflow, in which case the excision procedure is critical. The only acceptable methods we found were using a slow speed, oil cooled diamond saw or a laser, and even with them you have to be careful to not disturb the solder joints.
3) Make sure that your pull test procedure is controlled. Run it at a constant crosshead speed, make sure that you maintain a constant angle during testing, and make sure that your lead gripping is secure and consistent.
4) Check out your fracture modes to see where the solder joints are breaking during testing. You may have some joints breaking at the solder/lead interface and others at the solder/pad interface. This could give you some idea as to how good your soldering process is.
Regards,
Greg Bartlett
Mercury Computer Systems
Chelmsford, MA
[log in to unmask]
--------------------------------------
Date: 11/5/96 4:54 PM
To: Greg Bartlett
From: RICK VERNON
What are typical values expected during a peel test of gull wing leads of
36 to 38 mil width? We are experiencing great variation in peel strength,
on the order of approximately 4 lbs to 12 lbs for the same lead location on
different boards (D-pak style package). Profiles have been checked and
are "typical", solder paste from Alpha is fresh. I am looking for info on
what could be causing this joint strength variability in our process.
Thanks in advance.
Rick Vernon, Quality Engineer
[log in to unmask]
Pheonix International Corp.
***************************************************************************
* 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. *
***************************************************************************
------------------ RFC822 Header Follows ------------------
Received: by mailgate.mc.com with SMTP;5 Nov 1996 16:53:50 -0400
Received: from firewall.mc.com (firewall [192.148.197.15]) by jericho (8.6.11/8.6.11) with SMTP id QAA20130 for <[log in to unmask]>; Tue, 5 Nov 1996 16:53:50 -0500
Received: by firewall.mc.com id AA19644
(5.65c/IDA-1.4.4 for <[log in to unmask]>); Tue, 5 Nov 1996 16:53:48 -0500
Received: from ipc.org(168.113.24.64) by firewall via smap (V1.3)
id sma019637; Tue Nov 5 16:53:25 1996
Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI)
id PAA03974; Tue, 5 Nov 1996 15:35:03 -0800
Resent-Date: Tue, 5 Nov 1996 15:35:03 -0800
Received: by ipc.org (Smail3.1.28.1 #2)
id m0vKqML-0000ViC; Tue, 5 Nov 96 12:36 CST
Resent-Sender: [log in to unmask]
Old-Return-Path: <[log in to unmask]>
Message-Id: <[log in to unmask]>
X-Mailer: Novell GroupWise 4.1
Date: Tue, 05 Nov 1996 12:00:48 -0600
From: RICK VERNON <[log in to unmask]>
To: [log in to unmask]
Subject: Lead bond peel strength
Resent-Message-Id: <"jH0cE.0.hF9.eauVo"@ipc>
Resent-From: [log in to unmask]
X-Mailing-List: <[log in to unmask]> archive/latest/7417
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. *
***************************************************************************
|
