Re: [NTLK] eMate disassembly - do I *have* to de-solder?/my emate just came

From: Humphreys, David (david.humphreys_at_honeywell.com)
Date: Thu May 27 2004 - 07:15:27 PDT


> -----Original Message-----
> From: Woody Smith [mailto:woody_at_bitstream.net]
> Sent: Thursday, May 27, 2004 9:08 AM
> To: newtontalk_at_newtontalk.net
> Subject: Re: [NTLK] eMate disassembly - do I *have* to de-solder?/my
> emate just came
>
>
> Tin/Silver 96/4. Melting point 430F. Tin lead solder IIRC melts in
> the mid 700sF.
>
>
> Woody
>

I see. But...

96/4 Tin/Silver MP = 460F

60/40 Tin/Lead MP = 430F

63/37 Tin/Lead eutectic MP = 349F

Which do you think would cause the most damage due to heat?

The adhesive that holds the copper on the board will soften with applied heat. The advantage of using 63/37 is both
obvious and not so obvious. The lower temperature is the obvious point. There will be less chance of delaminating. The
not so obvious point is that the eutectic nature of the alloy means that once it starts to melt you know the temperature
to within a degree or so and you don't need as hot an iron.
Set the temp to 350F and that will be optimum.

Also, because of the eutectic nature of the alloy, the solidus phase is well defined. This means that there is no pasty
phase and the joint will 'set-up' almost immediately upon heat removal - definitely an advantage to avoiding
'cold-solder' joints.

Now you can use Tin/Silver solder but it is not the best for electronic board work. It is better as a hobbyist solder
for model railroad tracks due to the superior strength of the joints it makes.

Regards,

PCBman

-- 
This is the NewtonTalk list - http://www.newtontalk.net/ for all inquiries
Official Newton FAQ: http://www.chuma.org/newton/faq/
WikiWikiNewt for all kinds of articles: http://tools.unna.org/wikiwikinewt/


This archive was generated by hypermail 2.1.5 : Thu May 27 2004 - 10:00:02 PDT