Date:         Fri, 7 Aug 2009 01:54:17 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: 2.1l ECU - Solder Fatigue
Comments: To: Bob Stevens <mtbiker62@gmail.com>
In-Reply-To:  <586a66170908062208l3f7c4b14r6439916b90afa036@mail.gmail.co m>
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At 01:08 AM 8/7/2009, Bob Stevens wrote:
>when you reflow do you just heat the "crack" area with a soldering iron?
>Add solder?

You always have to add at least a touch of 60/40 or 63/37 rosin-core
solder to the tip to get good thermal contact with the rest.  Easiest
way is to place (~20 ga or finer) next to the pin and then melt it
with the iron so it flows into the existing solder.  Make sure the
joint is heated enough that the lead can move.  Add a bit more solder
if the existing stuff doesn't want to melt freely and leave a smooth
shiny joint.  Often helpful to do it from both sides of the board if
the lead is accessible from both sides.

This T-A board was not coated -- the Bosch ECUs I've seen (for 1.9l)
have a thickish clear coating to protect the board from
moisture.  I've had moderately good results simply soldering through
the coating (but it gums up the soldering tip so it needs a clean
after every joint).  I've also seen oxidation on component leads on
Bosch boards, which prevents the solder wetting the lead; so the
solder has to be removed and the lead scraped clean before resoldering.

The tip must be shiny-bright -- wipe it on a barely-damp cellulose
sponge before each joint and in between leave a drop of solder
hanging from it.  Never scrub the tip on the board -- the copper
foils have very little adhesion when they're hot, so treat them very gently.

  --
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'89 Po' White Star "Scamp"