How to resolder a cold solder connection?

"Phil Allison"

Look at the boards in you PC. See any flux?

If leaving the flux behind on a PCB were a very bad thing, then you would NEVER see it done by any equipment makers.

BTW:

Never hear of " NO clean " flux ???

Imbecile.

.... Phil

Yeah. It's crap. You seem to be unaware that de-soldering in the old flux will start to burn it and make it somewhat conductive and if not cleaned off can cause erratic operation in high impedance systems.Cleaning it off is therefore a good practice.

G=B2

If his mother had refused to f*ck an imbecile, Phil wouldn't be here.

Finding more webpages on how to fix this car, I came across this, probably from a different guy: "It is likely that a layer of hard oxide has built up inside the solder joint. The layer of hard oxide has to be removed by desoldering. Other than this, there are no known mechanical problem with the main relay. "

FTR, this followed "The Honda or Acura turns over but won't start in hot weather is a symptom of a main relay going bad. This is the result of the poor solder application from the factory. As a consequence, raise areas on the joint indicate a "dry joint" which can lead to an open circuit. The dry, open circuit is the main cause of no start. This is partly caused by the buildup of heat on the terminals which expand, contract and subject to vibrations.."

The relay is under the dash, so doesn't get the heat of the engine, but it seems just the heat of the sun, inside a closed car, then cooling off every day, thousands of times, causes problems, especially in the summer. The first guy recommends resoldering this main relay (fuel injectors and fuel pump) in any car over 8 years old.

The second guy acutally has an enalarged photo of the circuit board with several joints marked and the symptoms when each is bad, whn you hold the cursor over the circle! This must be a really common problem.

And a big tutorial on bad solder joints and resoldering.

But there are wackos who do great detail work too, so I didn't take his oxide story seriously until you guys confirmed it.

I see.

A 2001 Honda Accord EX, but all Hondas for the last 15 years seem to use this part.

Dang. I never clean joints I have soldered. :( I don't think anyone ever told me to before.

Thanks, and thanks everyone.

Me. too.

Yeah, but I thought that's what it always meant. In part, I'm sure, because from age 9 to 19, all I had was a wood-burning iron, which I never used to burn wood, and which was just a little too cold to solder with well. It worked. but in the process I had loads of cold solder joints that were really cold.

These are the reason I didnt' trust what I'd read about having to desolder before resoldering. A lot of bad info out there, by people who mean well.

Insufficient heat will do it for sure.

If you still have that tool, I think it would be very interesting to see if you could get good quality joints by polishing the parts to be joined and using added flux before applying heat.

Wood burning tools can generally achieve 500 F and

I'd never recommend this as a normal practice because there is not enough thermal headroom to do a consistently good job with larger joints and 60/40 solder is inferior to

(...)

I understand the reason why they show the poor technique initially. Hopefully, a user would recognize their way of doing it and have a chance to correct. This isn't too fantastic; I've seen some astoundingly bad technique used by techs in companies that you would instantly recognize the names of.

I got out of the biz before having to do *any* 'lead free' electronic soldering. I suspect that one could do acceptable repairs with the proper tools. I wouldn't expect that the proper techniques would change much at all.

--Winston

Since I'm the one who got the system working by removing the solder flux, I know it isn't equine excrement.

The loony bins are full of crazies like this POS.

I agree with just about everything presented on that page. This relay board is likely to be corroded in the defective joints, so I certainly see that removing the old solder is a very Good Idea.

However: 1) Dab compatible flux on each joint before soldering. A) I use standard old rosin flux so I selected a matching liquid flux. I apply it from a HDPE flux bottle.

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Fluxes work by dissolving metal and suspending oxides. They don't know when their job is complete. Sooooooo.... :)

(....)

Please let us know how it goes.

--Winston

The whole story is this. When I was 9, I was given a wood-burning iron with two extra tips and a finished wooden box to hold eveyrhing for my 9th brithday. Plus about 4 piieces of wood with sketches on them that I was supposed to brun lines on.

I liked it. Just then my older brother announced that his could be fixed, and my mother announced that we could return mine. Now I had hand-me-down toys and hand-me-down clothes all my life, and I didn't mind at all, but this time they were going to snatch it right out of my hands. I threw a tantrum, my last one. And I got to keep my iron.

But then I felt guilty. I never burned wood but i soldered with it for 5 to 7 years, until something in the solder ate a hole in the tip and the iron stopped working. Then I got my brother's iron, fixed it, and used that -- no longer feelign guilty, in fact retroactively not guilty -- for the same length of time, until it wore out the same way. Finally,at age 19 to 23, I bought myself a real soldering iron, with replaceble elements and tips.

What is it in the solder that eats up my wood burning irons and the tips. Oh, you said that in the other post: "Fluxes work by dissolving metal and suspending oxides.They don't know when their job is complete. Sooooooo.... :)"

I didn't know anything about different solders and lower melting tempersatures. Didn't know they existed, and it never occurred to me that would help.

Probably not, from what little I know. .

I'll look for one of these. I have some liquid flux, but I can't remember ifit's for electronic soldering, or copper plumbing! I'll check. It's by Oatey, so I guess it's for plumbing. :-) I'll see if I can find some flux before Sunday.

I hadn't read that line yet, but I think I would have had sense enough not to do it. Thanks for warning me.

She works almost every day, so iIt's scheduled for Sunday now. The weather says that Hurricane Irene will be off the coast of Delaware about that time, but I can't tell if it will be raining hard in Baltimore or not.

If the weather is good enough, maybe I can let you know by then.

(...)

Good on ya!

I suspect that is the case. Even the mild rosin flux in 'electronic solder' is an acid:

Repeated exposure of the iron tip to acid at high temperature is bound to cause pitting. As you know, soldering tips are plated to limit this damage.

The flux is magical stuff and proper 63/37 solder has a somewhat lower melting temperature (362 F) than the outmoded 60/40 alloy.

Combined, they might have allowed you to make good quality joints with a marginal iron. I don't know for sure, though.

You've got a lot of information available via the web. You should filter out the nonsense and be able to produce good quality solder joints easily, quickly and consistently.

We are *all* learning!

--Winston

The problem with solder is it chemically bonds to the copper.

Good for the connections, bad for the copper on the iron tip.

After a period of time, enough copper has migrated from the tip to the molten solder. Instant pit.

Nothing at all to do with the alleged acid content of the flux.

Jeff

From:

Savbit, Savbit 1, Sav1. Minimizes dissolution of copper. Originally designed to reduce erosion of the soldering iron tips. About 100 times slower erosion of copper than ordinary tin/lead alloys. Suitable for soldering thin copper platings and very thin copper wires.

That'll be what I learnt today. Thanks!

--Winston

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If you were near Silicon Gulch in CA, I would give you a bottle of the stuff I use. It's a great match to my solder, Kester 186.

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Excellent!

--Winston

It's the way I've always done it.

Sometimes you can get away with adding a bit of fresh solder -- or better, flux. But cleaning the joint is the preferred method.

Well, I learn something new ervery day.

I guess I've been doing this wrong for 50 years, but this time I'm going to resolder a relay from my neighbor, and I don't want her getting stuck, as she was last Monday, so my standards are higher than they would be for myself. .

But I guess now that I know better, I'lll do it this way for myself too.

Thanks, William, and everyone.

BTW, I could find liquid flux nearby, in time for the repair tomorrow, so I got flux paste. I thought I'd put a little on with a toothpick or matchstick?? If the hurrican means I don't work on the car tomorrow, should I go 10 miles farther to buy liquid flux?

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Why limit yourself? All four are the preferred method. Remove old, Flux, Solder, Clean.

Try it! You will be delighted.

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Flux paste will work fine as long as: 1) It matches the flux in your properly selected solder. (R, RMA or RA rosin in both cases).

The beauty of the liquid rosin flux is that it's difficult to supply *too little* to the joint.

--Winston

You want a good, mild RMA flux, not just liquid rosin. My favorite was Kester 1544, but I think they dropped that formula now that they concentrate on reflow solder products.

The proper method depends on what caused the failure. If it was properly wetted, but cracked around the pin becasue the board is single sided, a drop of fresh flux and a drop of new solder is fine. If it was caused by bad plating seperating from the pin, or poor soldering without proper wetting when it was made you will need to remove the old solder and clean the pins.

Thanks.

I don't know about future cases, but in this one** they say it's because it's in the passenger compartment and gets hot then cold every day in the summer, and cold then not every day in the winter. Plus the viibrations.

The temporary remedy was to open the car doors and let it cool off inside. (Although it wasn't a very hot day. It's run fine for the last week, also not very hot days. But it was in the 90's and hundreds for 4 to 6 weeks before this started.))

Nothing I read commented on the original solder job, IMO probably because they can't tell and most of them own Hondas and don't want to think it was made badly in the first place.