R/C Tech Forums - View Single Post - How to solder correctly (a not so brief lesson)

01-02-2010 | 06:05 PM

#93

marine6680

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Quote:

Originally Posted by Imbuter2000

Ok, I’m in the process of selecting the best products to buy for soldering the Tekin RX8 ESC&motor connectors and Traxxas plugs, so I finished my research on this PDF catalog of the products of Kester: http://www.bleifreiloeten.de/euro-to...ester_2005.pdf

The doubts are:

1) Sn63Pb37 or Sn62PB36Ag02?
A.f.a.i.k Sn63Pb37 has the advantage to have a fix melting point of 361°F while the Sn62PB36Ag02 has the disadvantage of having a not-fix melting point of 354-372 and the advantage of being more electrically conductive (correct me if I’m wrong).
What alloy is the best?

2) Kester 186 series Rosin Mildly-Activated (RMA) flux is available in 18, 25 or 36 percent solids formulations. What RMA formulation is the best?

3) the cored wire solder with RMA is described as “mildly activated rosin cored wire for sensitive electronic and military applications” while that with RA is described as “activated rosin core with excellent wetting action. Industry standard for most electrical and electronic hand soldering.”
About the “residue removal method” for both they write “Not required for most applications. May be removed by solvent or Kester’s #5768 Bio-Kleen saponifer”.
Does this description suggest the RA cored wire for my application? (because I don’t think that we can talk about “sensitive electronic” here)

4) the “metal solderability chart” states that if I’m trying to solder to “platinum, gold, copper, tin, solder, palladium, silver” I can use the RA or RMA cored wires (both are ok), while if I’m trying to solder to “nickel, cadmium, brass, lead, bronze, rhodium, beryllium copper” only RA cored wire is ok (RMA cored wire is not ok).
You wrote that Traxxas uses brass on their plugs. Does that implies that I should prefer RA cored wire? What’s the material that coats the RX8/T8 leads?

5) The cored wire is available with flux in three different percentages: 50 (1.1% weight), 58 (2.2% weight), 66 (3.3% weight).
What should I prefer? And what combination of cored wire + additional flux should I choose?

6) The cored wire is available in 0.25, 0.40, 0.50, 0.64, 0.75, 1.0, 1.2, 1.5, 2.5, 3.0 mm (or 0.010, 0.015, 0.020, 0.025, 0.031, 0.040, 0.050, 0.062, 0.093, 0.125 inches).
What do I choose?

Update: here's the latest/current PDF from Kester: http://www.kester.com/en-US/marketin...%208-02-07.pdf

1) 63/37 is much easier to use than any other solder due to the single melting point, and the wettability of lead solders. the other has silver and is stronger, not better electrically. The extra strength is not needed, the only time the solder should be under that much stress is in a severe crash, and you have other problems if the crash is bad enough to break solder joints.

2) Solids content really will not matter to the average user. High percentage is for circuit boards that have high density of components. More sticky, a bit stronger, and less can be used during production assembly. It does leave more residue to clean with the higher percentage

3) RA is stronger and not really needed on new parts often. Use RMA it is better for your iron as well. I also suggest cleaning always.

4) RMA will work. The military uses RMA only, because it give the best balance of flux's different properties. Stick with RMA for general use work.

As far as what is on the tekin posts, I could not tell you, their customer service should be able to.

5) New components and non-corroded parts don't need much flux. I would get a medium amount of flux core for general use. Even the smaller amount is good for new parts. and just a light coat is good for extra flux, try the flux pen/re-work pen.

6) If you plan on soldering anything smaller than a battery connector, .5mm is a good size. For ESC and connectors the 1mm will work well. The smaller stuff can always be doubled up for larger parts. The .75 might be easier to use on connectors and ESC's, preventing using too much.

7) Don't over think it.

It isn't a fighter jet.

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