Lead Free Solder

[Ed Kotkiewicz]

"Robert A. Taylor" wrote:

> Fred,
>
> I want to answer your query via the server because I also want to get
> feedback on my opinion to your solder question.
>
> First of all, I would only use eutectic (60/40 approx.) solder because it
> has the lowest melting temp of any combination of tin, lead, silver, etc.
> As you know, I always use heat sinks on all components soldered into
> equipment to prevent component degradation due to heat during the soldering
> process.

EK> Bob, I have to disagree with you here.  I was NASA certified for soldering
when I was in the Navy during a timeframe when the Navy was coming to realize
that most folks shouldn't handle a soldering iron without special training.
(The same seems very true with kit builders....sigh).  The lowest melting temp
solder is 63/37 in ratio.  This ratio has no "plastic state" and goes directly
from solid to liquid.  60/40 was selected as a compromise to this need.  63/37
is more expensive.

> Second, there are all kinds of 60/40 solder, some you would only use if you
> were caught with a desperate need and it was the only solder you could find.
> I classify the solder Heath supplied with the kits as near to that
> specification.  Of all the solders I have used, my favorite is Kester "44"
> 0.032 dia. wire solder.  It is a resin core solder that is active enough to
> clean well during the tinning process, yet inactive enough after soldering
> to prevent corrosion if left on the joint.  I used alcohol or 1:1:1
> trichlorethelene (no longer permitted to be sold I think) to clean the
> joints after soldering to prevent flux damage in the long term.

EK> Very correct procedure in cleaning the flux.  People with BA's should also
consider the long range effects of tube temp cycling on solder.  I am currently
parting out an HW-101 and the solder condition is very poor.  During attempts to
clean up, I find the solder "globbing" and have removed the degraded solder and
replaced with fresh.

> Lastly, use a temperature controlled grounded soldering iron.  The
> temperature and size of the tip were determined by the size of the component
> to be soldered.  You want a tip large enough and/or hot enough to perform
> the soldering job quickly before the heat could bring the heat sinks up to a
> dangerous temperature and therefore pass the temperature on to the
> component.  Heat sinks ranged from the light-weight alum clips sold for that
> purpose to using them plus alligator clips to attach cotton swabs filled
> with alcohol to the leads and/or the components.  This is especially needed
> for solid state devices.  The grounded iron tip is very important with these
> items to prevent leakage current from the iron from wiping out the device
> either now or in the future due to electrostatic discharge.

EK> Also very sound advise

> Fred, I know you just asked about solder, but it is only one element in the
> process.
>
> I welcome the group input on this.
>
> 73's Bob, W2CNB

EK> Stating things like what you have done here adds to the knowledge that
others, less fortunate then you or I, need to keep this hobby alive.

Ed

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