 
| Mime-Version: |
1.0 |
| Content-Type: |
text/plain; charset="us-ascii" |
| Old-Return-Path: |
|
| Date: |
Mon, 11 Nov 1996 09:33:08 -0500 |
| Precedence: |
list |
| Resent-From: |
|
| Resent-Sender: |
|
| X-Status: |
|
| Status: |
O |
| X-Mailing-List: |
|
| X-Sender: |
|
| TO: |
|
| Return-Path: |
<TechNet-request> |
| X-Loop: |
|
| Resent-Message-ID: |
<"6e4nY3.0.L4D.9rkXo"@ipc> |
| Subject: |
|
| From: |
|
| Received: |
by ipc.org (Smail3.1.28.1 #2)
id m0vMsN0-0000TYC; Mon, 11 Nov 96 03:09 CST |
| From [log in to unmask] Thu Nov 14 10: |
47:11 1996 |
| X-Mailer: |
Windows Eudora Light Version 1.5.4 (16) |
| Message-Id: |
|
| Parts/Attachments: |
|
|
Jim,
If the solder significantly stiffens the leads then it will also increase the
resonant frequency and reduce the magnitude of vibration for a given level of
excitation, so whether the higher stress concentration is significant is not
immediately obvious. Can't you just re-run the FEA with the new geometry?
David Whalley
>The fact of the matter is that the components are ceramic QFPs on polyimide.
>Our concern isn't with thermal excursions, though, since we restrain our
>assemblies and control the surface TCE to ~7 ppm/degrees C. Our FEA revealed
>high stress concentrations during vibration where the lead is attached to the
>component. The concern is that solder in the bend will shorten the lead
length
>from the component body to the first bend, thus increasing the stress during
>vibration.
***************************************************************************
* 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. *
***************************************************************************
|
|
|
