Hi Christer -
Good luck on soldering to the stainless steel - it's one of the
tougher materials to solder to and takes a very aggressive flux
chemistry. I can help out with your stainless steel questions - CRES
stands for Corrosion Resistant Steel which is a common acronym for
stainless steel. Your 18-8 description of stainless steel covers a lot
of alloys - 303 is a specific stainless steel alloy that is for free
machining applications. It has a lower sulfur content and a small
addition of aluminum to promote the free machining aspects. The CTE of
303 is 16.4 um/mK in the 21-315 C envelope and 18.5 um/mK in the
70-1000 C envelope. With the ceramic having a CTE 7.74 um/mK of your
assessment of the cracking cause sounds plausible.
Dave Hillman
Rockwell Collins
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______________________________ Reply Separator _________________________________
Subject: Stainless steel
Author: [log in to unmask] at ccmgw1
Date: 2/19/97 12:19 PM
Dear Technetters.
We have been trying to solder a connector of plated stainless steel to a
ceramic substrate. We have not been sucessful so far.
Cracks occur in the solder joint after soldering.
We think the coefficient of thermal expansion in the stainless steel is
to high.
The material in the connector is CRES 303. (Acc to ASTM 484 and 582)
What material is the connector made of? The supplier is an american
company.
The CRES 303 says nothing to me.
Is the material an ordinary 18-8 stainless steel (18%NI and 8%Cr)?
In that case the coefficient of thermal expansion is approx 18 ppm and
that could explain the cracks.
Regards
Christer Marklund
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