On 11/30/2011 7:30 PM, Grinder wrote:
> On 11/30/2011 2:20 PM, John McGaw wrote:
>> On 11/30/2011 12:09 PM, Grinder wrote:
>>> I'm finally getting to the end of a 2-lb spool of 60/40 0.05" (18 gauge?)
>>> rosin core solder I bought from Radio Shack years ago. This time around,
>>> I'm considering:
>>>
>>> * 63/37
>>> * 0.032 (21 gauge?)
>>> * Water-soluble rosin core
>>>
>>> Frankly, I'm enough of a hedonist that I'm happy to use as much lead as
>>> needed to make my life easier.
>>>
>>> I do mostly circuit board repair, and some PCB prototyping. Any
>>> opinions or
>>> recommendations as to what solder works the best?
>>
>> That sounds like a good spec and that blend is eutectic for tin-lead,
>> the diameter is right for semi-delicate work and water-soluble flux is
>> pretty much a given. I'm still using up a 2-pound roll of Kester 62/36/2
>> (with silver) which I first got decades ago when I was fixing Tektronix
>> test equipment which called for it at the time and I'm getting old
>> enough that more solder purchases seem unlikely.
>
> What does that bit of silver do for the joint?
>

Very little in most circumstances except that it probably conducts slightly
better than regular tin/lead. Tektronix, back in the dark ages, used a
method of construction which depended on ceramic 'sticks' with silver fired
onto them to produce ultra-high impedance low capacitance circuitry. Other
components were soldered onto the silver patches on the ceramic and silver
in the solder prevented it from literally dissolving the fired silver and
weakening the bond. All very high-tech back then but obsolete long ago.
This type of solder is sold now for use with components having
silver-plated leads but those are pretty rare. So there I was with this
roll of expensive solder when my old 2-pound roll of regular stuff got used
up so rather than waste it I started using the odd stuff. I use so little
now that it will surely outlive me.