Re: [amsat-bb] NASA SPEC Connectors

[Jon Ogden <na9d@xxxxxxxxxxxxxx>]

on 3/5/01 6:37 PM, paul.willmott@omsl.bm at paul.willmott@omsl.bm wrote:

> This intriges me, ... unless I have this wrong you are saying that you can't
> trust soldered joints on a spacecraft, ... hummm, .... what is different
> about a connector (like Bob want's to wire up), and a PCB, ... in my
> experience a crimp connection is less reliable compared to a soldered joint,
> ... and if heat is the isuue what about the actual PCB boards dripping with
> wet solder.

I sent this to Bob privately, but since there's a lot of discussion, I'll
voice it publicly for what it's worth.

I believe that one must be careful with soldering gold contacts to wires
using standard nickle-tin-lead solder.  The reason is that I believe you can
get gold migration into the solder.  This will end up causing the solder
joint to get brittle and eventually break.  Gold is kinda funky.  For
example, you have to use a nickel barrier layer on a connector in order to
have a gold plated center pin otherwise you won't get gold adhesion, etc.

I think gold embrittlement is the biggest reason to avoid solder in
something like connectors like this.  You are connecting all sorts of
dissimilar metals together with an active agent (flux in the solder) in
contact with all of them.

I am not a material expert and I may have this all wrong.  I'll admit it if
that's the case.  It just seems like there is something in the back of my
mind that I have heard or read about somewhere in the past on this topic.

73,

Jon
NA9D

-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)

Member:  ARRL, AMSAT, DXCC, NRA

http://www.qsl.net/ke9na

"A life lived in fear is a life half lived."

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