All,

Hand soldering is very much an art form. I was pretty good at it, but have been 
learning over the years. I have learned a lot from Brian, KF4VOO as well as 
watching NASA training videos on YouTube and from other sources. These topics 
I’ve discussed on the air, but putting them in writing for the rest of the 
class <grin>.

Let me give these out as a series of points:
1. Use Eutectic solder - 63/37. That’s 63% tin and 37%lead. Eutectic means that 
both components melt/freeze at the same temperature. This is extremely 
important for hand-soldering. 60/40 is easier to manufacture, but gives poorer 
results because it was also designed for flow soldering. None of that lead-free 
crap. My XYL, Dasha is an environmental engineer (and a licensed Professional 
Engineer in the State of TEXAS). She’s not worried about lead contamination 
from our soldering leaching into the ground water and killing kittens and 
puppies and that’s good enough for me.

2. The flux should be rosin core. Period.

3. The diameter should be skinny. 0.46mm - the reason is that we don’t want too 
much solder in the joint.

And for today’s topic: Flux.

In an ideal solder joint, there should just be the proper fillet of solder 
where the junction is formed. Those of you who are welders understand fillets.

The amount of flux inside even the best solder tends to cause the operator to 
apply too much solder to the joint. The internal flux dissipates before the 
heat-bridge gets the solder flowed.

The answer - add flux to the joint. I suggest liquid flux where the rosin is 
dissolved in alcohol.

I got some good flux from Fry’s and picked up a Weller squeeze bottle with a 
needle in it. This dispenser SUCKS. Flux all over the work and the bench. A 
waste of money and time in cleaning. Liquid flux is sticky until completely 
dried out.

The solution to the problem with the SOLUTION was to get a really good 
bottle+cap+dispensing needle. I found a deal on Amazon linked here:

https://www.amazon.com/gp/product/B01G2QZQG8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
 
<https://www.amazon.com/gp/product/B01G2QZQG8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1>

This kit is for “Vape” - whatever that is. It’s an inexpensive kit of various 
bottles and dispensing needles. The needles are for syringes, but not for the 
pokey kind - just a blunt tip.

In the bottle with yellow cap and yellow needle is the flux. It’s all happy and 
drips out just the right amount. The black is even finer and filled with 
lubricating oil for my guns. I’ll use the other bottles and sizes for various 
glues and such.


Here’s a link to the flux I got at Fry’s, but available on Amazon:

https://www.amazon.com/MG-Chemicals-8351-125ML-Halogen-Bottle/dp/B00S16UAGE/ref=sr_1_4?s=industrial&ie=UTF8&qid=1471028240&sr=1-4&keywords=liquid+flux
 
<https://www.amazon.com/MG-Chemicals-8351-125ML-Halogen-Bottle/dp/B00S16UAGE/ref=sr_1_4?s=industrial&ie=UTF8&qid=1471028240&sr=1-4&keywords=liquid+flux>

Just a drop or 2 makes a big difference. Keeping 100 drops OFF the bench makes 
it funner.

73

Bill Crowell, N4HPG
Pearland, TX
[email protected] <mailto:[email protected]>
I prefer to live a life of galvanic isolation.

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