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Recommendation for liquid flux please

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  • Member since
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  • From: Shenandoah Valley
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Recommendation for liquid flux please
Posted by BigDaddy on Monday, December 13, 2021 4:17 PM

A clinic at Imonium recommended Kester several years ago.  Maybe I got the wrong version but it did nothing at all.

What do you use?

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by 7j43k on Monday, December 13, 2021 4:34 PM

I use this:

https://www.mgchemicals.com/products/soldering-supplies/soldering-flux/rosin-flux/

You can get it from Amazon.  And elsewhere, I am sure.

I generally like to clean the suface of oxides/sulfides first, so that there's bright metal.  

I apply it using a toothpick.

 

Ed

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Posted by tstage on Monday, December 13, 2021 4:36 PM

Henry,

Any reason you want liquid flux over paste flux?  I like and prefer the paste because it stays in place before soldering.  The liquid is just a less viscuous version of it.

The rosin solder paste I use is a 2 oz jar I picked up from Radio Shack 15 or so years ago.  It will probably end up being a lifetime supply for me.  I always clean up any leftover flux afterwards with 99% isopropyl alcohol & a cotton swab.

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 richhotrain on Monday, December 13, 2021 4:43 PM

I use paste for flux and 60/40 rosin core solder.

Rich

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Posted by betamax on Monday, December 13, 2021 4:58 PM

Possible that you have the wrong type of flux or solder (Lead vs. Lead Free)?

Also, flux does have a shelf life. Today most suppliers will state that, but for stuff made years ago, who knows what they put in it.

MG Chemicals or Kester is a good choice.

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Posted by 7j43k on Monday, December 13, 2021 5:43 PM

My liquid flux stays in place as long as I don't use too much.

 

Ed

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Posted by BigDaddy on Monday, December 13, 2021 5:48 PM

tstage
Any reason you want liquid flux over paste flux?

Yes, people have mentioned in the past that they use it and since I have 2 cans of paste flux that I cannot find since I moved I thought I would try liquid.

betamax
Possible that you have the wrong type of flux or solde

I think I tried 951:

 

 Kester 951 is a halogen-free, non-rosin organic flux designed for soldering conventional and surface mount circuit board assemblies. The extremely low solids content (2.0%) and nature of the activator system results in practically NO RESIDUE left on the assembly after soldering. Boards are dry and cosmetically clean after soldering. There are no residues to interfere with electrical testing. Kester 951 exhibits improved soldering performance to minimize solder bridges (shorts) and excessive solder defects. This flux is suitable for automotive, computer, telecommunications and other applications where reliability considerations are critical. The surface insulation resistance on soldered boards is higher than that provided by typical organic water-soluble fluxes. Kester 951 contains a corrosion inhibitor such that no corrosion products are formed when bare copper surfaces are exposed to humid environments.

 

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by wrench567 on Monday, December 13, 2021 8:05 PM

   Am I missing something? I must have installed over a hundred decoders, wired layouts and built 7 portable modules and really seen no reason to use flux. Why all of a sudden is there a need for flux? Clean contacts, tin the wire and solder pad and solder. I have two sizes of solder. One is .015 and the other is.032.  The .032 is used primarily for buss wires the .015 is for everything else.

     Pete.

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Posted by tstage on Monday, December 13, 2021 8:21 PM

Pete,

Even with rosin core solder, I sometimes like just a smidgen of rosin flux paste to ensure a nice shiny soldered connection.  I want mine to glisten in the light.

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 BumpyJack68 on Monday, December 13, 2021 8:22 PM

Well Pete, we all can't be soldering wizards :D I'm old and shaky with declining  vision so I'll take all the help I can get. I use a thick liquid in a syringe called Chipquic?

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Posted by Overmod on Monday, December 13, 2021 8:45 PM

951 and 959T are both available in pen form for fine work.  Note that you do NOT want 959; the T is significant.  This has about 1/2% rosin in it and should work with any of the rosin-core solders (I still recommend ~63-37 eutectics)

A 'pastier' liquid is Amtech NC-557, which I consider just a joy to use.  It does not come 'native' in little end-user hobby bottles, so be sure of your source...

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Posted by hgodling on Monday, December 13, 2021 10:05 PM

I recently started using the MG chemicals 835 mentioned previously. It has worked very well for me. I do use lead free solder so my needs were a bit different. I would expect it will work well if you are using 60/40 solder as well. 

I put it in a bottle with a needle tip. That works ok. I think I may go back to paste in the future though. It is hard to keep the liquid localized and it drips a bit. 

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Posted by 7j43k on Monday, December 13, 2021 10:10 PM

wrench567

   Am I missing something? I must have installed over a hundred decoders, wired layouts and built 7 portable modules and really seen no reason to use flux. Why all of a sudden is there a need for flux? Clean contacts, tin the wire and solder pad and solder. I have two sizes of solder. One is .015 and the other is.032.  The .032 is used primarily for buss wires the .015 is for everything else.

     Pete.

 

 

Flux is like insurance.  You don't need it until you need it.

I've used flux on every solder joint I've made for the past 50 years.  I have no idea which of those would have been fine if I hadn't used it.

 

Ed

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Posted by crossthedog on Tuesday, December 14, 2021 12:07 AM

wrench567
Why all of a sudden is there a need for flux?

Pete, I too was weirded by the sudden arrival of flux into my consciousness a year or so ago when I started model railroading again. We didn't use it when we did our layouts as kids. But one thing I like about it -- I use a paste, applied with a toothpick, probably because that's what Ed suggested -- I like that you can engineer the path that the solder will take through a rail joint by dabbing flux inside the rail joiner and on both sides of the joint. I'll even sometimes do the unthinkable: apply heat to the outside of the rail while applying the solder to the inside. The flux sucks the solder right through the joint to the outside. I'm still not that great at finishing off clean, but I've learned how to make the solder fill the joint completely, and I think it would be harder without the flux. YMMV. Cheers,

-Matt

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

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Posted by betamax on Tuesday, December 14, 2021 3:54 AM

wrench567

   Am I missing something? I must have installed over a hundred decoders, wired layouts and built 7 portable modules and really seen no reason to use flux. Why all of a sudden is there a need for flux? 

For starters, there may not be enough flux in light gauge wire solders.

Also, over time the lead poisons the flux, making it less effective. It also dries out.

Besides, a little flux won't hurt, and often will make a big improvement in the result.

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Posted by rrebell on Tuesday, December 14, 2021 8:17 AM

BigDaddy

 

 
tstage
Any reason you want liquid flux over paste flux?

 

Yes, people have mentioned in the past that they use it and since I have 2 cans of paste flux that I cannot find since I moved I thought I would try liquid.

 

 
betamax
Possible that you have the wrong type of flux or solde

 

I think I tried 951:

 

 

 

 Kester 951 is a halogen-free, non-rosin organic flux designed for soldering conventional and surface mount circuit board assemblies. The extremely low solids content (2.0%) and nature of the activator system results in practically NO RESIDUE left on the assembly after soldering. Boards are dry and cosmetically clean after soldering. There are no residues to interfere with electrical testing. Kester 951 exhibits improved soldering performance to minimize solder bridges (shorts) and excessive solder defects. This flux is suitable for automotive, computer, telecommunications and other applications where reliability considerations are critical. The surface insulation resistance on soldered boards is higher than that provided by typical organic water-soluble fluxes. Kester 951 contains a corrosion inhibitor such that no corrosion products are formed when bare copper surfaces are exposed to humid environments.

 

 

 

 

If I am not mistaken, this flux is used for doing floats on printed circut boards, not meant for other things.

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Posted by wrench567 on Tuesday, December 14, 2021 9:19 AM

BumpyJack68
Well Pete, we all can't be soldering wizards :D I'm old and shaky with declining  vision so I'll take all the help I can get. I use a thick liquid in a syringe called Chipquic?

I am in no way a soldering wizard. I'm also old and shaky with declining vision. You know your getting old when you spend ten minutes looking for the glasses you already are wearing.

I just remember being told not to use flux for electronics. When you constantly hear flux contains corrosive compounds that later can ruin your work unless it is cleaned off and the acid neutralized. I'm willing to try it. The only real issue I am having with soldering is the silver colored wire over the pure copper. I tend to put too much solder when tinning the silver wire.

 
Pete.
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Posted by 7j43k on Tuesday, December 14, 2021 9:43 AM

Pete,

What you were told about not using flux must have been garbled.

 

"Not using flux" applies to using ACID flux.  Acid flux works nicely on things like copper plumbing pipes.  But with wiring, especially stranded, there's big worries about the acid getting "carried away", and damaging the wire.

I was taught how to solder by my father back in the fifties, who worked in electronics, .  HE used flux.

I worked soldering for gov'mint projects.  WE used flux.  As directed.  I preferred their liquid flux to my father's old paste flux.  When it got hot, it would solidify, and you could remove it with a probe and a brush.  Sure wouldn't mind using it again.

Use the RIGHT flux.  That's generally rosin-based. 

 

 

Ed

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