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Flux in soldering

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  • Member since
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Posted by gregc on Saturday, April 11, 2020 3:50 AM

rrinker
 Another useful thing I didn;t realize was so useful until I got one recently - a holder for the solder roll.

i work with about a foot a solder at a time rather than from the ~1 lb roll.

i wrap the solder around my fingers to form a loop.   saves space on the bench and easier to handle.    i throw out the piece when it's about a 1/2" long

greg - Philadelphia & Reading / Reading

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Posted by maxman on Saturday, April 11, 2020 12:14 AM

RR_Mel

Normally a one pound roll of solder lasts me around 10 years.  I just bought a one pound roll off eBay.
 
I prefer .8mm/.031” solder for working on circuit boards, I even use it to solder code 83 & 100 NS rail with it.
 
 

Many different choices at that link.  May I ask which one you decided on?

The Kester is supposed to be good, but what is the difference between the two Kester products that appear the same but are about $30 difference in price?

Thanks

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Posted by woodone on Friday, April 10, 2020 6:25 PM

I use a silver bearing solder, little lower melt point and a bit more strength -.015 diameter, I use a paste flux that was used by a decoder manufacture. Works real well, I solder at about 550 degrees.

 

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Posted by rrinker on Friday, April 10, 2020 4:23 PM

 I think that's the same size I use. I know it's thing - but since it's not in a roll holder, it's not easy to see the end where the markings are.

 Another useful thing I didn;t realize was so useful until I got one recently - a holder for the solder roll.

https://www.amazon.com/Delcast-SL-RL-Solder-Dispenser-Reel/dp/B00PQF98X4/ref=sr_1_2?dchild=1&keywords=solder+roll+holder&qid=1586553585&s=hi&sr=1-2

They also make double ones if you have 2 kinds, like 2 different sizes, or a plain 63/37 and a silver solder. Makes working from the big spools so much easier.

                                       --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by RR_Mel on Friday, April 10, 2020 1:29 PM

Normally a one pound roll of solder lasts me around 10 years.  I just bought a one pound roll off eBay.
 
I prefer .8mm/.031” solder for working on circuit boards, I even use it to solder code 83 & 100 NS rail with it.
 
 
I also bought a can of non crossive Soldering Paste off eBay.
 
 
 
 
Mel
 
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
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Posted by rrinker on Friday, April 10, 2020 12:53 PM

 Only solder I ever got from HD was the bif fat stuff for plumbing. For decoders, fine wires, and even if I wanted to build a fence from brass wire (for HO scale or smaller, at least), I used a much finer solder which I haven't generally seen in HD (not that I really look. I bought a 1 pound spool back when I bought my flux, fromt he same supplier. ANd still have plenty left. This spool has supplied solder to numbers PCBs, a bunch of decoder installs, soldering the track joints on my previous layout, and all those rail joiners with feeders - aka, every rail joiner except where I needed an electrical gap, all came from this spool of solder and it's still mostly full. There are numerous suppliers and places to get spools of solder - I'm sure Amazon is one of them.

                                    --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by gregc on Friday, April 10, 2020 12:47 PM

i've taken for granted that component leads and wire are tinned (copper is not silver).  I don't do much soldering for non electrical purposes, but I think solder paster is necessary when soldering non-electrical components that can be soldered

greg - Philadelphia & Reading / Reading

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Posted by kasskaboose on Friday, April 10, 2020 8:59 AM

Besides the uses above, I use flux in making fences.  The solder seems to bind much easier to hold the wires once I first add flux. 

You're prob better off getting solder from HD. 

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Posted by rrinker on Friday, April 10, 2020 7:39 AM

 It's not that the acid eats through the copper wire and PCB - if it did that, it would eat through the copper pipe is is normally used for. It's that it provides an electrolyte when a current flows through the connection that corrodes away the wire.

Either way - never use acid based flux on electrical or electronic things. Rosin flux is still an acid, just a much weaker one than typical plumbing flux and it more thoroughly activated when heat is applied. Which is why even proper electronic fluxes should be rinsed off after soldering. Eventually they will turn ugly if left alone - open up some cheap electronics sometime, where they couldn't be bothered to clean the residue, and look how gunky some things are.

 Track is the same, unless you are 100% dead rail, electricity passes through the rails, so acid flux is a no-no there too. Fast Tracks recommends acid flux for assembling their turnouts - well, if you assemble them at the bench, you can pop them off the fixture, and before attaching the wood ties, thoroughly rinse them off, which is ALSO a step in the instructions - so then you are OK. But soldering feeders to track already laid on your layout - little hard to rinse off the flux residue. 

                                        --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by betamax on Friday, April 10, 2020 3:16 AM

jjdamnit

The flux I use is Lead-free, water-soluble, paste-type found in the plumbing aisle of most hardware and big-box stores. 

There is a reason why decoder manufacturers recommend no flux be used.  Too many damaged decoders returned under warranty for replacement. Cause: ACID flux.

If you bought your flux in the plumbing section, it is probably acid based, as these types of fluxes need to be aggressive to work with pipe. You will never completely eliminate the acid, it will be eating at the connections until they fail.

The correct type for electrical work is rosin flux. A little flux goes a long way. Rosin flux isn't something you usually find at a hardware store.

The second cause of decoder failures: ESD.

 

 

Tags: DCC , soldering , ESD
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Posted by jjdamnit on Thursday, April 9, 2020 2:18 PM

Hello All,

I use "Fine Electrical Rosin Core Solder" (63% tin, 37% lead) with a 0.032" diameter for electrical components. For soldering track I use a 40% tin, 30% lead with a 0.05" diameter.

The flux I use is Lead-free, water-soluble, paste-type found in the plumbing aisle of most hardware and big-box stores. 

My soldering iron is set to 600ºƒ.

I have been doing a lot of re-motoring and decoder installations lately and this combination works well for me.

As far as isopropyl alcohol clean-up, yes I do it but not all the time. I have not experienced much oxidation on electrical components but I have on soldering nickel-silver track.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by tstage on Thursday, April 9, 2020 1:06 PM

While I do use rosin-core solder when soldering, I still like and prefer rosin paste flux because it can be applied with a toothpick and stays in place until heated.  After soldering I clean the area with 99% isopropyl alcohol and a Q-tip.  And, even though the decoder manufacturer's say NOT to use flux when soldering onto their boards, I still use it because it assures me the cleanest and shiniest bonds between soldering pads and wires.

If your soldering iron is set to the optimal temperature for your task and you work quickly, you run very little risk of frying components.  And, as mentioned, I always clean off any boards I'm soldering to with 99% isopropyl.

Tom

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by rrinker on Thursday, April 9, 2020 12:29 PM

 I used to pretty much never add any - rosin core solder seemed to always work fine. Newer leaded components seem to be using lesser quality metal so it does seem to help (a lot of Chinese parts are using steel or some other magnetic metal - the cut off bits stick in my magnetic screw trays). On my PCBs, I clean them with isopropyl before assembly, and I usually only add a littel paste flux to the heavier components - ones with thick leads like terminal blocks.

 I do use flux when soldering rail - it works very well by putting some in the rail joiner, then putting the two pieces of track together. It helps wick the solder through the entire joiner, making a very solid connection without blobs sticking up that need to be filed off.

 Bus to feeder - I don't bother, the rosin core solder and the 150 watt soldering gun make quick work of that.

 I use Solder Safe brand water soluable flux. Excess and the residue cleans off easily, but as I make bigger boards I need to get some actual cleaner, using isopropyl wipes is fine for small boards but with lots of components it's too easy to end up with a board that has no flux residue but looks like someone pulled apart a cattail over it.

 I got a 4oz jar of the paste - about 12 years ago. Not even 1/4 used yet. Somewhere I have a 2oz bottle of the gel, unopened. This brand comes in paste, gel, or liquid. I didn't bother with liquid since the instructions say that if you want liquid, you can thin the gel.

                                  --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by gregc on Thursday, April 9, 2020 11:21 AM

i've never used solder paste until recently when i found that it worked much better on some leaded components (diode leads for some reason).   I've used good quality resin core solder (Weller is one) for decades.

greg - Philadelphia & Reading / Reading

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Posted by RR_Mel on Thursday, April 9, 2020 11:18 AM

Just make sure what ever you use is corrosion free rosin.  I’d been using an “electronic rosin paste” for 20 years when I found out it wasn’t corrosion free, it screwed up an Arduino board.
 
 
 
Mel
 
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
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Flux in soldering
Posted by rrebell on Thursday, April 9, 2020 11:03 AM

There are many types these days of rosin, the paste I use and the liquid and a gel. So for our applications, which is best. I have flux from radio shack now, I have found their solder is not always the best so is that true of their flux? Have Kestor souder by the way.

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