Date:         Mon, 28 Feb 2011 01:38:53 -0500
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: Unbelievable, was  Re: Spare ECU
Comments: To: Tom Hargrave <thargrav@hiwaay.net>
In-Reply-To:  <051401cbd70d$f0acbc30$d2063490$@net>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 01:08 AM 2/28/2011, Tom Hargrave wrote:
>The solder fatigue you took pictures of is common for electronics
>that have been in a vehicle for a long time.

Ayuh. And not by any means just automotive gear.  So why aren't there
more images out there?

>  usually the parts that fatigue are heavier power resistors, caps
> or inductors. They seem to be more susceptible than smaller, lighter parts.

To amplify on that somewhat:  heavy parts, parts that stand away from
the board, parts subject to thermal cycling and most particularly
parts with pronounced thermal cycling that are mechanically connected
to a stiff external structure (like the devices connected to the heat
sink in our ECUs).  But the curious thing I'm finding in the ECUs is
bad joints in small light parts that sit right on the board, in
low-power DIP leads, in the flattened-ribbon connections between
boards.  I find that surprising.

Yours,
David