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Re: MicroWave: Re: Indium solder question from KA0RYT (EN34DW - MINN.)



Oh my Paul you have hit a nerve that is only hours old.  I asked for some
Indium/Silver solder as we have a number of solar cells awaiting 
construction in a satellite project.  Unfortunately even with the
suggestion of a manufacturer, we distroyed the cells with 60/40 solder.
      We need an answer!  Not only is the connections between the cells
important but we need to know what Epoxy---non gassing type--- that will
work.  So far, only the Indium solder has been suggested and nothing
regarding the "glue" need to fasten the cells to a satellite face been
suggested.  The world has all kinds of suggestions but nothing specific
that we can tell students BUILDING a CUBESAT what to do!  Cliff K7RR


On Tue, 19 Sep 2000, Paul Wade W1GHZ (N1BWT) & Beth Wade N1SAI wrote:

> I had lots of experience years ago with indium solder, ALL BAD!
> when I worked at Microwave Semiconductor, they used indium solder
> to assemble microwave amplifiers; they ended up replacing every one 
> of them when the joints failed.  they would come back with alumina 
> (ceramic) circuit boards rattling around in the case.
> 
> as I recall, there were two major problems: 
> 
> 1. gold and indium form an amalgam that is very brittle and perhaps 
>    somewhat porous.
> 
> 2. the indium solder required a very active flux (read: ACID).  since
>    flux is never completely removed, any moisture that seeped in later
>    would spread the acid around and finish off the joint.  
> 
> I recall reading a posting recently looking for a flux-free indium 
> solder used for photocells.  this would eliminate the second problem.
> 
> however, the first problem is not so easy, and probably occurs with 
> silver as well.  I learned a lot about metallurgy and ceramics the 
> hard way, and education is always expensive.
> 
> so I'd recommend staying away from indium.  ordinary solder works
> very well with copper, and silver solders are available with higher
> and lower melting points if you are trying to have more than one
> soldering temp.
> 
> 73
> paul
> 
> 
> At 09:26 PM 9/18/00 EDT, you wrote:
> >Hello !! My name is Ron and I was directed to ask you for some info on your  
> >experiences with the indium solder that W2DRZ was discussing on the VHF 
> >reflector ....... I am considering trying with this solder for experimental 
> >soldering on some 432 cavity input preamps . I have been constructing 432
> and 
> >144 cavity input preamps for several years (please take a look at the
> Central 
> >States noise figure results to see my "work") . I am curious if there are
> any 
> >bad effects from using this type of solder on the copper pipe type cavitys 
> >that I produce here ?? Any info would be appreciated - I am planning to 
> >silver plate these too ........ 73 and tnx again , Ron Bergantzel KA0RYT 
> >
> >
> 
> 

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