Flux - you learn something new every day

[chicken45]

How do you tin the iron? Every time I apply solder to the tip of the iron, it just beads up and runs away...


-Cody F.

http://www.radioshack.com/product/index.jsp?productId=2062721
Buy it in a local store.

[chicken45]

http://www.radioshack.com/product/index.jsp?productId=15693336
also great.

[davefoxx]

I've owned that Radio Shack Tip Cleaner/Tinner Compound for about twenty years.  No kidding.  But, I find that keeping the tip of the iron tinned with solder and wiped clean on a folded-up, wet paper towel really doesn't require me to use the compound.  By the way, I use Radio Shack's rosin flux (paste), which will probably last me a lifetime.  For that matter, my soldering iron and its tip are also twenty years old, and I expect to get another twenty years of them.

DFF

[Chris333]

I dip my tip right into the paste flux to clean it.  Like tip dip for wire feed welders.

[pnolan48]

My older brother was the solder guru of the computer industry, when components were soldered to boards--yeah, he's all of 70 years old. His advice to me many years ago mirrors that of previous posts: cleanliness, cleanliness, cleanliness, followed by good mechanical contact, followed by non-acid flux. He also stressed high tin/low lead solder, polishing the tip with progressively finer grades of sandpaper before tinning, and keeping a wet sponge available at all times.

I'm still a lousy solderer, but that is more my unwillingness to follow his every step to the letter.

[chicken45]

I'm still relatively new to this soldering, but I can tell you some of my observations. That tip tinner is a must for me. Before, even with new tips I could not get the tip tinned like I can with the tip tinner. It may be technique, or lack thereof, but it works great.
Went I went to order my new chisel tips, I decided to go nuts and stock up on other things to make it worth the shipping cost. One of which was that brass tip cleaner. It's an easy way to clean the tip, but a wet towel also works.

[VonRyan]

If that is happening, your tip is probably dirty.

Another MUST... you need to have a clean wet sponge!   (Another thing I didn't know when I started soldering
as a teenager 100 million years ago).   Keep wiping that hot iron on a wet sponge and get it as clean as you can before
you try to apply any solder for tinning.
You may find, if the tip is all covered with dark, burned junk, that you can only get the solder to stick on
one or two spots.  Do it.  Then wipe on the wet sponge and repeat, until you get rid of all burn junk and get a completely
clean, silver, solder-coated tip.


If you've never cleaned the tip and never tinned it, it is probably all dark and cruddy.
 If it is just a plain copper or copper alloy tip, then carefully sand off that junk with some
very very fine sandpaper (like 220 or even finer... you don't want to be rasping on it with coarse stuff).
When you see clean shiney metal, your solder should stick to it.   

But again, apply a little solder, then wipe it on the sponge.

DO NOT USE SANDPAPER if you have an iron-clad, or other "long life" tip.  The iron cladding will be sanded off and the tip
will be ruined.

Speaking of which.... if you can get the iron clad or "long life" tips for your iron, go to the store right now
and buy one.    It makes soldering so much easier.   Plain copper tips, the kind that come in most cheap blister-pack
soldering irons, get dirty and cruddy fast and are hard to keep clean and tinned.

Solder wouldn't ever stick to it when the tip was brand new....
I just don't seem to have good luck with soldering irons. My dirt-cheap radio-shack iron did well untill i started cleaning the tip, then it crapped out. Now my $12 weller iron doesn't seem to want to do much of anything in any hurry... which is why I'm leary of doing decoder hard-wiring.
It seems the more money I spend to "better my modeling" the more money I seem to have wasted...



-Cody F.

[mmagliaro]

I think that using $12 soldering irons is going to be an excercise in total frustration, honestly.
Poor tips, lousy heat control, etc.

I have not bought a soldering iron in so many years that I'm not a good one to ask what you should
get now.  But those $10 blister-pack type irons are usually awful, and I have used those
a few times in the past couple of years (other peoples').

The two soldering irons I use are an old Archer (Radio Shack) back from 20+ years ago when
they still made good tools and sold lots of electronic parts.  It has a long-life iron-clad tip
and it is wonderful for a basic iron with no heat control.   It cost $20-$30 back THEN.
My other one is a benchtop Ungar 9000 (also a dinosaur) with settable heat control.
It's long out of production and I can't get parts for it anymore.  But the few that are around
cost hundreds of dollars.

I am guessing that you need to get something more in the $50 - $100 range before a soldering
iron starts to be reasonable to use these days.

[SkipGear]

I've uesd flux for years, but not on electronics. Only when soldering brass kits and on really stubborn joints. I've found that clean, pre tinned joints solder fine with nothing more than the flux in rosin core solder. Yes, I pre-tin SMD LED's.

As far as soldering irons..... I use 3 diferent ones depending on the application.

ANTEX M12 - 12W micro iron - Great for SMD stuff, hot enough for most wire connections and track. I use this iron more than any other right now. The Antex can be had on Ebay - I used to buy them direct from the US distributor (its a UK company) for $15, now they are $24. They offer needle sharp tips for them also.
http://www.ebay.com/itm/Antex-Soldering-Iron-M12-incl-bit-/390120452319#ht_393wt_1170

PACE Digital, Temp. controled Solder Station - Up to 900 deg. Enough said, if you can't solder a joint with this, it's not going to happen. The PACE is an industrial unit that a friend gave me when their repair shop was updating to new ESD safe equipement. What I would suggest is either a Hakko 888 if you want digital control or a Trakpower  TK-950 for a simpler system. We use the Trakpower at the shop I work at and it has worked great for 2 years getting used for hours every day.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXATBK&P=ML

Weller D220 - 2 stage gun 150-200W if I remember correctly. Great for under layout and other stuff where you don't want a hot iron laying around in between joints. This is actually what I learned to solder with. I hated pencil irons because of all the cheapo irons I had tried before were never hot enough and the tips would reject solder.

That Ungar iron that Max has is a classic. I have the RC version called a Super Race Station. It is stored away because I can't get parts for it and the heating element is on it's last leg. If I ever find parts support for it again, it will be back on the bench.

[mmagliaro]

Off-topic, but Tony.... there is a way to replace the heating element in the Ungar 9000.

If you scour the web far and wide, you will not find one.  BUT...

I found part 9908, which is for a different Ungar iron, at Newark Electronics and bought it years ago.
It works.

Newark doesn't have it anymore.  At least I can't find it.
But  https://www.galco.com/techdoc/welr/9911hc_cp.pdf    shows it, so maybe you can get it there.

PROBLEM:  That element is a thicker ceramic "stick" than the original in the 9000.  So although the two prongs
mate into the connector inside the barrel, and it appears to be the correct resistance and works,
you can't fit the tips into he barrel anymore because the element takes up too much room.
(The tips have a half-flatted shank that is supposed to shove into the barrel alongside the element).

I found, however, that if I flat-filed that half-flat part down a lot, it WOULD fit in there, and then it works.
It took some doing, but now I know what to do, and the station works well.

Now... back to your regularly scheduled thread.

[mmagliaro]

But wait, there's more!
Tonight, I was soldering a simple bronze wire loop through a trinket so my stepdaughter could wear it on a chain
around her neck.   I was going to just solder the wire ends together with regular solder.

Then I thought that silver-bearing solder would be stronger, except that in all my life, I've never been able to
get it to flow worth a darn or stick to anything.   And then I thought, BWA HA HA HA.... "FLUX!"

Yes, a drop of flux, and that silver-bearing solder flowed right on there smooth, clean, and neat.

This is like discovering penicillin.   

[peteski]

I'm glad Max discovered that using flux really works.  Most solders have flux core, so when that solder is actually applied to the joint when soldering, the flux in the solder wire is usually enough to make a clean solder joint. But in many instances, I feel that extra flux (possibly more active than the one included in the solder core) produces a cleaner solder joint.

In other instances, like soldering leads to SMD LEDs, a different soldering technique is used. For that type of  solder joints, the only solder which will be used to create the solder joint is actually on the tip of the soldering iron.  There is no flux in that tiny amount of molten solder. But if some flux is applied to the solder pads of the SMD LED, it provides the perfect amount of flux needed for a clean solder joint. The SMD LED solder pads are also gold plated and very clean. I don't find it necessary to pre-tin them. Gold with some flux on it accepts solder very easily and quickly. Plus, every tie the SMD LED is heated increases chances of damaging it.

[robert3985]

Here's a word of caution. Etch these words into your soldering brain.

Although flux is great for soldering joints and some electrical contacts, as model builders it's important for those joints to last a long time.  Certain fluxes can really make the solder flow and stick, but in the long run, they will cause your joint to self-destruct over a time period of a few months to a few years.

These fluxes are highly acid and are available easily at your local The Home Depot's or Lowe's and are designed for soldering stuff like copper pipe for your toilets and bear such names as "Plumber's Honey" and work great for soldering pipes using a big-ol' Propane torch when building your house.

Way back when, when I was learning to build N-scale turnouts so I could use Railcraft Code 70 flex on my Ntrak modules (as a compromise between scale appearance and Ntrak's requirement to use code 80 track), I discovered highly acidic flux works GREAT for making solder flow!  I also realized that this flux was highly acidic, so I washed my bench-made turnouts in warm, soapy water and got rid of all the visible signs of it.  After two years of being painted and ballasted, every single turnout I had built started disintegrating with even the plastic Delrin ties going brittle and white.  This caused me to scrap three extensive modules after five years of attempting to fix the problem by resoldering all of the joints on my PCB turnouts as they broke.

After that horror story, I was introduced to a brand of flux that a manufacturer of N-scale catenary was using to construct his models, and that discovery rocked my soldering world just like Max's discovery of plain ol' flux.  Two reasons...it works better than Plumber's Honey and its slight acidity is neutralized by the heat of soldering.  Since those days 25 years ago, all of my brass and NS model building has been done using this brand of flux, and turnouts and models I made that long ago have not exhibited a single moment of self-destructive behavior!

So, make sure the flux you choose is either non-acidic, or that it self-neutralizes or you'll be sorry down the road, believe me.

[VonRyan]

I've never had to use flux, as the solder always flowed well with my old radio-shack cheepie iron... that was, until someone told me I should clean my tip, and after that everything just kept getting worse.
Now my more expensive $12 Weller iron doesn't want to do anything for anybody.
If I wasn't down to my last $2, I would probably buy a new iron and see how that works, but $2 won't even get me a thing of flux, let alone a new iron.
But enough of me bemoaning things...
I want to see more of Max's latest steam project! 


-Cody F.

[peteski]

Bob,
the caution about using fluxes is very wise.  I would hope that most people would know better and only use mild or mildly-activated fluxes.  Stuff designed for electronic or electrical soldering.

There are instances (like soldering steel or some brass photoetched items) where I use more aggressive fluxes (like Tix Flux which is zinc chloride). But I always make sure that I clean the residual flux from the joints.


Cody:  The cheap Radio Shack irons (which I also used when I was around your age) have nickle-plated copper tips.  The nickel disintegrates easily and then the copper gets pitted by the molten solder rather quickly. I used to just file them to a point, whenever they got dull (when the tip was cold of course).  Eventually (just like a wooden pencil), the tip would get too short to be useful.

I suspect that the Weller iron you have uses a copper tip which is iron plated, then has thin nickle plating, then  it is tinned (factory-covered with solder).  The secret to its longevity (and ease of soldering, or its heat transfer ability) is directly tied to keeping it clean and always coated with a layer of molten solder.

It sounds like your iron's tip is dry and burned.  The layer of tin has burned off. Try gently scraping the tip with a hobby knife (when cold). Try to get the dark crud off the tip's surface. Don't try using sandpaper.  Once the tip is cleaned (looks shinier), plug the iron in.

If you have some flux, apply it to the tip as it is warming.  That will help in tinning it. If you just have a rosin core solder, hold it to the cleaned tip as the soldering iron is warming up. At some point the solder will start to melt and hopefully it will stick to the cleaned metal of the tip.  Apply more solder around the tip (watch out in case some of the molten solder drips off the tip).  If all goes well, the solder will eventually evenly coat the tip.

Once the tip is properly tinned, you should have no problem soldering.  to keep the tip in good condition, it needs to be cleaned often.  If you are on low budget, find a piece of a kitchen sponge. Make sure it is the cheap cellulose sponge, not a rubber sponge. Wet the sponge and squeeze most of the water out, just keeping it moist.  You can then wipe the tip on it. That cleans off any burned matter from the tip. Then touch some solder to the tip, giving it again a coating of liquid solder.  You should make this a habit.  Clean and tin it before putting the iron down after soldering.  It sounds like a pain, but once you develop the habit, you won't even realize you're doing it,

If you don't have one, I also recommend buying a soldering iron stand. You should be able to find an inexpensive one and I can tell you that it comes in really handy. Besides, stands usually also include some sort of a tip cleaner (usually just a sponge).

The problem with inexpensive pencil irons is that they, due to lack of temperature control, run really hot.  That shortens the tip's life and makes soldering electronic circuits (without burning them up) rather challenging. But I've built many electronic circuits using a cheap iron. Hoverer, back then, the components and circuit board were much larger than today's N scale DCC decoders.  But if you are quick, and have an iron with a clean tinned tip, you can do it.