[AR] Re: [AR] Re: Solder in spaaaaace
- From: "Grassy Noel" <grassynoel@xxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Thu, 20 Feb 2014 19:14:16 +0800
Tin will change from the white metallic allotrope to the grey diamond-like one
at low temps. Not sure if this is important though.
----- Reply message -----
From: qbert@xxxxxxxxxxxxxxx
To: <arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Solder in spaaaaace
Date: Thu, Feb 20, 2014 07:03
I can vouch for that several generations of our autopilot ended being scrapped
due to "whiskers" and the highest some of those ever went was 10,000 feet.
Robert
At 01:23 PM 2/19/2014, you wrote:
>Vacuum is not required. Pure tin under stress will grow whiskers in >any
>environment. Not using pure tin is the only real prevention, >though some
>conformal coating materials can at least prevent >whiskers coming in contact
>with conductive surfaces.
>
>Sent from my iPad
>
> > On Feb 19, 2014, at 1:38 PM, Peter Fairbrother > <zenadsl6186@xxxxxxxxx>
> > wrote:
> >
> >> On 19/02/14 00:43, Allen Newcomb wrote:
> >> Leaded solder is the only acceptable solder for space. There is a RoHS
> >> exemption for this.
> >
> >
> > There is? Where?
> >
> > Thanks,
> >
> > Unleaded solder WILL grow whiskers in vacuum.
> >
> > :( Yeah.
> >
> >
> > -- Peter Fairbrother
> >
> >>
> >> -Allen
> >>
> >>
> >>
> >> On Tue, Feb 18, 2014 at 5:17 PM, Peter Fairbrother
> >> <zenadsl6186@xxxxxxxxx <mailto:zenadsl6186@xxxxxxxxx>> wrote:
> >>
> >> I have, reluctantly, decided to change from using tin/lead solder to
> >> lead-free.
> >>
> >> There seem to be two main types of commercial lead-free solder, one
> >> mostly tin with a little copper and about 4% silver, and one without
> >> the silver. The bismuth/indium containing alloys are not really
> >> readily available.
> >>
> >> My question; is either of the main ones better as far as whisker
> >> growth, pest etc goes?
> >>
> >> Any other suggestions for a general purpose solder which is usable
> >> long-term in vacuum?
> >>
> >>
> >> Thanks,
> >>
> >>
> >> -- Peter Fairbrother
> >
> >
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