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Re: [Amps] current threads about silver solder and resoldering

To: amps@contesting.com
Subject: Re: [Amps] current threads about silver solder and resoldering
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Sat, 01 Sep 2012 15:20:00 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
On 9/1/2012 2:26 PM, Manfred Mornhinweg wrote:
Bill,

Most things are labeled the largest component to the smallest by weight,

Yes, for example the list of chemicals in food is like that. But solder
normally isn't. I think there is an ISO standard defining solder alloys,
and it requires tin contents to be specified first. I would have to
search for it to provide any evidence, though.

Such as eutectic alloy of 63% tin, 37% lead.
Oddly enough with that ratio by weight the number of atoms of each is
equal.
One atom of lead to one of tin.

I strongly disagree. Tin has much lower atomic weight than lead. If
there is far more tin, by weight, than lead, then the ratio of atoms of
tin to atoms of lead is even larger. According to my calculation, 63/37
solder has slightly more than 3 atoms of tin for each atom of lead.


Lead = 207.2
Tin 118.7

Figuring gram molecular weights

63% of 118.7 = 74.781grams/molecules
37% of 207.2 = 76.664grams/molecules

They are close but not exact or they just round off to the nearest % for simplicity.

I would think to be eutectic they would be the same, but due to measuring tolerances this is pretty close.

73

Roger (K8RI)

Manfred

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