Electronics Repair - Soldering Guide

[DCH]

MOD EDIT: This basic information on attempting repairs on any UAV we fly is invaluable to anyone attempting to go where you have not gone before...

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OP EDIT: The subject of soldering came up in a post recently, followed by some thoughts that caught my attention, so I jumped in to clear up some misconceptions about soldering. This is an important subject since many of us are hands-on people and like to do our repairs. @PatR has given some very good tips below along with a link to a soldering tutorial that does a very good job of teaching the basic fundamentals of Soldering. This is right up my alley -perhaps more of a main street for me, so I will be happy to follow this post and give advice and tips as needed.
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I have been a NASA certified soldering instructor for decades. Questions and answers like these and the term "Soldering Gun" cause me to shudder. There is so much more to soldering than melting solder with a hot iron. Just because it melted on the connection, doesn't mean it's good solid solder joint, and it doesn't mean it won't fail under vibration in flight! If you don't know what you are doing, don't touch it with a soldering iron -and NEVER use a "Soldering Gun" on delicate electronic components. It is extremely important to learn the proper fundamentals of soldering before attempting to make repairs or modifications that require soldering on an aircraft of any kind. And it is wise to practice on something that doesn't cost hundreds of dollars to replace when you accidentally lift a trace off the PCB while soldering, or have it fall out of the sky due to a cold solder joint. By guess and by golly have no place in the realm of aircraft soldering, both in the model world and in the real world.

 

[PatR]

Soldering temp/wattage is dependent on the type of solder used and the items to be soldered. High lead content (60-40) solder can make use of lower temps while zero or low lead content and silver solder require higher temperatures. Small diameter/surface items do not require as much heat as large diameter/large surface area items do. Multistrand silicone wire requires more heat than common copper multistrand wire. Solder tabs usually require more heat than common wire. You want the item to be soldered to heat up quickly to prevent heat from the soldering process to migrate away from the solder joint and damage items not involved in the soldering process. So there's no "one size fits all" soldering temperature, and we haven't even gotten started on tip sizes and shapes.

For bottom level info about soldering can be found in the following link but there's a lot more to it than what the article provides. I'll let DCH add more that he finds appropriate as he has been certified in the process. I am not certified. One thing is certain. take some time to learn the process on parts and equipment you won't ever have to depend on. Something that can fall out of the sky and cause harm is not the place to learn how to solder.
How To Solder: A Complete Beginners Guide - Makerspaces.com

 

[DCH]

I'll let DCH add more that he finds appropriate as he has been certified in the process. I am not certified. One thing is certain. take some time to learn the process on parts and equipment you won't ever have to depend on. Something that can fall out of the sky and cause harm is not the place to learn how to solder.
How To Solder: A Complete Beginners Guide - Makerspaces.com

WoW! Great article Pat, I looked it over and it seems quite comprehensive. Like I stated above there is so much more to it than melting solder, as one can see by reading it, and so much more than I could begin to explain in a post. Thanks for digging that up.That should be stickied somewhere.

I will add the following notes and a tip tip.
In the video I see the component he is soldering is moving around as he solders the first lead. This is the only red flag I see. It is very important for the lead to have a good mechanical connection before applying solder. Never rely on solder to fill the entire gap or make the physical/mechanical connection. The component leads should have been bent more to ensure a good physical contact, and keep it from moving while the solder cools to prevent a "Cold" joint. Any movement while the solder is cooling will create a cold joint, so will cooling it too fast by blowing on the joint. A cold solder joint will not be shiny and bright, but appear to be a dull gray. Unacceptable for aircraft standards.

He also did not cover (or I did not read about -I only skimmed it) what constitutes a good solder joint or how to tell it apart from a bad one. The main thing to look for is a shiny bright smooth solder puddle after it cools. It should not look dull grey, and not be a bead that appears to sit on top -even if it is bright and shiny. And you want to make sure the solder passes thru to the other side if soldering a circuit board and produces the same appearance there.

After soldering a joint, it is standard practice to remove all traces of excess flux and any tiny solder droplets with alcohol when you are finished. The job is not complete until the cleanup is done.

A final note on the use of a sponge or other tip cleaner. I can't stress enough the importance of a clean tip to ensure smooth even and fast heat transfer. You want to get in and get out ASAP, never linger a moment longer that it takes for the solder to flow into the joint. The sponge has been accepted as a good cleaner since the soldering iron was invented. It is still my go-to tip cleaner but there are better alternatives. Just make sure the sponge has been completely moistened then rung out as much as you can, you want as little water on it as possible because it will cool the tip the moment before you will be using it. I prefer to clean the tip on the sponge, then re-tin it with extra solder, then flick the excess off the tip just prior to touching the joint. I use a dedicated dish to catch the excess solder droplets I fling off the tip. Perfect results every time.

 

[AH-1G]

I understand where you're coming from @DCH.
My response to the other post was in hopes for folks to go on line and also research what is needed for proper soldering. People should do more research, but laziness is a virtue with many.
I wasn't about to go into details you, so next time I'll keep my fingers from playing with this keyboard,but nahhhhh.

My father (Eng) used to design/develop his own circuit boards, complete with all the components attached, I use to help once in awhile, but watched more than actually help. I have soldered many components in my lifetime, including the wires recently that were ripped out of the H camera. (not once had any issues).

 

[DCH]

I understand where you're coming from @DCH.
My response to the other post was in hopes for folks to go on line and also research what is needed for proper soldering. People should do more research, but laziness is a virtue with many.

Hey AH-1G, didn't recognize the new image! So professional, how was I to know it was just the same ol you? No worries LOL, your 60s vintage soldering iron painted a pretty scary image in my minds eye! ...Had to go wash it out with soap before posting my knee jerk reaction!

But it served as a great reason to bring up this subject, it is really needed and I'm happy to share what I know. I will probably come back and add more tips as I think of them.

 

[Eugene]

WoW! Great article Pat, I looked it over and it seems quite comprehensive. Like I stated above there is so much more to it than melting solder, as one can see by reading it, and so much more than I could begin to explain in a post. Thanks for digging that up.That should be stickied somewhere.

I will add the following notes and a tip tip.
In the video I see the component he is soldering is moving around as he solders the first lead. This is the only red flag I see. It is very important for the lead to have a good mechanical connection before applying solder. Never rely on solder to fill the entire gap or make the physical/mechanical connection. The component leads should have been bent more to ensure a good physical contact, and keep it from moving while the solder cools to prevent a "Cold" joint. Any movement while the solder is cooling will create a cold joint that will not be shiny, bur rather a dull gray. Unacceptable for aircraft standards.

He also did not cover (or I did not read about -only skimmed it) what constitutes a good solder joint from a bad one, and how to tell. The main thing to look for is a shiny bright smooth solder puddle after it cools. It should not look cloudy grey, and not be a bead that appears to sit on top. And you want to make sure the solder passes thru to the other side if soldering a circuit board and produces the same appearance there.

After soldering a joint, it is standard practice to remove all traces of excess flux and any tiny solder droplets with alcohol when you are finished. The job is not complete until the cleanup is done.

A final note on the use of a sponge or other tip cleaner. I can't stress enough the importance of a clean tip to ensure smooth even and fast heat transfer. You want to get it and get out ASAP, never linger a moment longer that it takes for the solder to flow into the joint. The sponge has been accepted as a good cleaner since the soldering iron was invented. It is still my go-to tip cleaner but there are better alternatives. Just make sure the sponge has been completely moistened then rung out as much as you can, you want as little water on it as possible because it will cool the tip the moment before you will be using it. I prefer to clean the tip on the sponge, then re-tin it with extra solder, then flick the excess off the tip just prior to touching the joint. I use a dedicated dish to catch the excess solder droplets I fling off the tip. Perfect results every time.

That was the whole purpose of the message is to find out much as I can before started anything ! You had to start somewhere, I'm sure you did. Some people have more experience than other at something ! I thought that was the purpose of the forum is to ask question ! ! !

 

[DCH]

That was the whole purpose of the message is to find out much as I can before started anything

And now many others will benefit from your question. Like I always say, the only stupid question, it the one you don't ask!

 

[Eagle's Eye Video]

I second that! @Eugene do not be slighted by any of this... Your question led to some great reference links that will be valuable to many people... which is why it became a separate stickied thread.

 

[DCH]

So to keep this on the topic I will delete my posts.

I like a man who tidies up after himself!

 

[HRife]

In today's micro electronics and surface mount components it is a real need to have a precision, temp controlled iron. Not like my old ham homebrew days when a Weller "gun" was the tool of choice! in fact.....if you know an old "ham" he could be a great resource.

 

[DCH]

in fact.....if you know an old "ham" he could be a great resource.

Hey Buddy! Who you callin "Old"?
Okay yes, I am getting on in years, and yes I am a HAM, but I'm anything but OLD!
And @HRife is right! The trusty Weller Soldering Gun is still the tool of choice that HAMs use for soldering PL259 connectors, ...or soldering a broken track on a Abrams tank!

~K7WWH~

 

[Docdor]

I am not a Ham but will share one tip I have used to clean the tiny holes in circuit boards. Acetylene torch tip cleaners or root canal files work very well prior to soldering or resoldering. They freshen the metal, remove old solder, or the oxidation/corrosion leading to a better joint.

 

[DCH]

I am not a Ham but will share one tip I have used to clean the tiny holes in circuit boards. Acetylene torch tip cleaners or root canal files work very well prior to soldering or resoldering. They freshen the metal, remove old solder, or the oxidation/corrosion leading to a better joint.

This is true, however one must be very careful not to remove the copper plating inside the hole that feeds thru and connects the two pads on each side of the PCB. The best way to remove this stubborn solder is to heat the pad on one side or the other and quickly blow the solder out with compressed air, or use a solder sucker to pull it out.

One thing to remember is the copper plating that form the pads is very thin and can easily be lifted off the PCB with too much heat. Reworking a PCB is a delicate procedure, much more so than soldering a new component to a new pad. PCB construction varies quite a bit and so does the thickness of the solder pads. Some cheaper boards are impossible to repair because the thin plating comes off far too easily and doesn't usually survive the fist de-soldering attempt.

 

[Docdor]

This is true, however one must be very careful not to remove the copper plating inside the hole that feeds thru and connects the two pads on each side of the PCB. The best way to remove this stubborn solder is to heat the pad on one side or the other and quickly blow the solder out with compressed air, or use a solder sucker to pull it out.

One thing to remember is the copper plating that form the pads is very thin and can easily be lifted off the PCB with too much heat. Reworking a PCB is a delicate procedure, much more so than soldering a new component to a new pad. PCB construction varies quite a bit and so does the thickness of the solder pads. Some cheaper boards are impossible to repair because the thin plating comes off far too easily and doesn't usually survive the fist de-soldering attempt.

That is very true. Most things nowadays are made to be thrown away and not to be repaired. For a few cents more it would be easily and predictably repairable.

 

[HRife]

Hey Buddy! Who you callin "Old"?
Okay yes, I am getting on in years, and yes I am a HAM, but I'm anything but OLD!
And @HRife is right! The trusty Weller Soldering Gun is still the tool of choice that HAMs use for soldering PL259 connectors, ...or soldering a broken track on a Abrams tank!

~K7WWH~

... --- .-. .-. -.-- --... ...--

 

[DCH]

... --- .-. .-. -.-- --... ...--

-. --- / -. . . -.. / - --- / .- .--. --- .-.. --- --. .. --.. . -.-.--

 

[Magic]

The best way to remove this stubborn solder is to heat the pad on one side or the other and quickly blow the solder out with compressed air, or use a solder sucker to pull it out.
.

Good advice ... If you are used to being an expert and you have a lot of tools for each type of work ..
The best way to work quickly in the kitchen is a simple wooden toothpick ..))) Cheap and angry!

 

[JMichael]

Great Thread DCH .
I love listening to the pros .
Never a waste of time .

 

[JMichael]

You guys may already be aware of this product.
I found this yesterday and yes , I have one on the way to my house now .
Very affordable but not cheap quality .
Not a sales pitch , just a link to the video that won me over .

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[PatR]

Good advice ... If you are used to being an expert and you have a lot of tools for each type of work ..
The best way to work quickly in the kitchen is a simple wooden toothpick ..))) Cheap and angry!

Solder wick is pretty cheap, easy to use, and a lot more effective, than tooth picks