Received: |
by ipc.org (Smail3.1.28.1 #2)
id m0wYbUG-000BjJC; Mon, 2 Jun 97 13:05 CDT |
Lines: |
34 |
Old-Return-Path: |
|
Date: |
Mon, 02 Jun 1997 18:35:36 GMT |
Precedence: |
list |
Reply-To: |
|
Resent-Sender: |
|
From [log in to unmask] Mon Jun 2 13: |
13:42 1997 |
Status: |
O |
X-Mailing-List: |
|
TO: |
|
Return-Path: |
<TechNet-request> |
>From bergdi Mon Jun 2 13: |
06:20 1997 |
X-Status: |
|
Resent-Message-ID: |
<"R3tK81.0.GjP.rjmap"@ipc> |
Subject: |
|
From: |
|
X-Loop: |
|
Resent-From: |
|
X-Mailer: |
PCElm 1.10 |
Message-Id: |
|
Parts/Attachments: |
|
|
((Sent this on Friday, but it didn't appear to come through. Apologies if it
repeats.))
I would be interested in TechNetters' comments about a rework system we have
been asked to consider.
The process involves adding a low temperature solder alloy
(tin/lead/bismuth/indium/? - not sure of the %ages) to the
existing solder joints at low temperature; the alloys mix and then
allow the SMD to be removed at the low temperature. The lands are cleaned and
then the device replaced as normal (soldering iron and conventional solder).
The pros are rework at low-to-zero capital cost (maybe good for field
service), and at low temperature. The cons are that it's actually about a 10
step process, and I believe takes longer than conventioanl methods. Couldn't be
easily used for BGAs, best for QFPs etc where you can access the joints.
My initial worry was the idea of remnants of the low temp alloy would be left
in the new joint - what effect would that have on joint reliability? But,
probably only a low concentration of bismuth might be introduced to new solder
joint.
Any other thoughts? Comments? I know that it's not a newly invented process -
why isn't it used more commonly?
Peter
--
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Peter Swanson Oxfordshire, England
INTERTRONICS
[log in to unmask] http://www.cygnetuk.demon.co.uk
Suppliers of materials and consumables to the electronics & related industries
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]> *
* with <subject: subscribe/unsubscribe> and no text in the body. *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] *
***************************************************************************
|
|
|