Crimping & Soldering - Keys to Connection Performance and Longevity

[admin]

Audio and Video Cables are not just dependent on the wire or cable used, or the connectors used. The quality of the connection between the wire or cable and connector is just as important, if not more so. The biggest problem with the audio/video cable market is that marketing departments choose fads and fallacies, non-applicable specifications and pseudo science over real world objective measurements and tried and true methods of creating wire and cable assemblies that will last for many years with high quality results. Today we're going to look at those unsung heroes of our A/V world, the ones that hold it all together - the crimp and the solder joints.

Discuss "Crimping & Soldering - Keys to Connection Performance and Longevity" here. Read the article.

 

[jneutron]

A well written piece. My thanks to AH and Ram.

I recommend the inclusion of an additional rule for solder joints.

If possible, do not use the solder as the sole support of the wire. The pictures of the yellow and brown wire have the bare conductor going through the hole, and bent back towards the insulated wire. That is how it should be. Many times, people (me included) will simply tin the conductor and terminal and lay it on the terminal for soldering such that only a lap joint is there. In xlr and D sub connectors for example, you may not have a choice.

Good work..

Thanks, John

 

[Alex2507]

Perfect timing on this as I now have some crossovers to build.

 

[lsiberian]

Perfect timing on this as I now have some crossovers to build.

I need to do some soldering too. I'm calling it. Prophet!

 

[tsteves]

jneutron
Thanks for the kind words. Your point is fantastic. There are plenty of solder joints that have to be made without a good mechanical connection between parts. Solder cups is an excellent example, or soldering a ground wire to the back of a potentiometer inside a guitar. The way to treat these situations is to keep the wire and contact in as close physical contact with each other as is possible while soldering. The solder should flow into all of the minute gaps but never be used to form a "bridge" between the wire and contact. For example with cups, you don't stick the wire into the middle of the cup, you lay it against the inside of the cup. We all get a bit lazy sometimes when doing our own personal cables, but if you force yourself to get into good habits, you usually just start to do it the right way all the time naturally.

Tom Steves
RAM Electronics

 

[JLMEMT]

Me three!

Though I have never done circuit boards before, so hopefully it goes well.

 

[Djizasse]

Perfect timing on this as I now have some crossovers to build.

Perfect timing indeed. And thanks for the tip John

I do have a RS6's crossover that's expected to arrive this week.

Also on the way are a few XLR, TRS and RCA plugs. I'll make a few cables to connect the DCX to my new computer pre-amp interface, to the receiver and to the sub's amp.

To top it up I need to finish my led mood light for the back of the LCD.

Prophet indeed

 

[Alex2507]

Here's a pretty informative link to some soldering stuff:

http://tangentsoft.net/elec/movies/

I'm posting it here thinking it will be of additional help to us.

 

[Midcow2]

Soldering is an art form

Reiterating a soldering joint should not be the only physical support; It is better to twist the wires and make a physical connection before soldering if possible. In addtion it is better if you clamp the wire with a smal solder spring clamp rather than trying to hold it with your free hand.This assures you don't get a cold solder.

While not found much more, do not use acid core solder on electrical circuits; use only rosin core solder.

Although it didn't really say in the article, too get the best capillary actionand not get excessive solder, it is best to heat the wire and touch the solder to the wire. This is not necessarily true with printed circuit boards.

Printed circuit boards are even more of an art form and you need to practice practive before attempting. You need to use as low of heat soldering irorn as possible and very careful not to over heat or touch adjacent components. If you are just starting and especially on integrated circuits, it is safer to solder a separate socket and then plug in the IC. Again printed circuit board you have to have enough heat to get a good solder joint (not a cold solder joint) and not so much that you burn the circuit board or another component.
Too bad Heathkits not longer exist; they were a great way to hone your soldering skills as wee as the Dynaco kits.

Solder flux is good to remove excess solder or to un-solder a component. there are also some inexpensive one handed sprint loaded vacuums that will suck up liquid solder.

Crimping is okay if you have the proper equipment for the correct size wire; personally like soldering better! Crimping seems to to be a good match for automobile electrical connections, but IHO not the best audio solution for DIY.If you need to check with the "pull test" then you probably should not be crimping! I tend to stay completely away from spade connectors unless the are the closed circle kind; even with a secure wire connection the connector nut can come loose. Crimping is okay for banana plugs as long as you have the exact equipment desigend for the banana plugs. I like banana plugs much better that are the locking kind with set screws to secure the wre and also the expansion point to secure the banana connection into the audio equipment.


Good Luck!

MidCow2

P.S. - And just how many soldering irons should a person have ?

P.S.S - Now that I am retired, I just don't seem to have any free time

 

[tsteves]

Alex2507
Great link, and very good info.
I'd just say that the soldering iron choice is very important. Hakko and Hexacon irons can be found cheap on ebay. I use a Hakko solder station, as well as an ancient hexacon with an ancient, but well cared for tip. Don't use more wattage than you need, especially for circuit boards. Clean the tip constantly!

 

[tsteves]

Midcow2
I can tell you are an old school solderer like me!
But I would like to comment on a few of your comments... not to nit pick, just to clarify.

In addtion it is better if you clamp the wire with a smal solder spring clamp rather than trying to hold it with your free hand.This assures you don't get a cold solder.

This is sometimes a solution, but for one thing it depends on your pain threshold! If the clip is used directly on the bare wire and contact the clip is a heatsink, if used to hold the wire farther back it is way too time consuming to set up. Good solderers have callouses!

it is best to heat the wire and touch the solder to the wire

You need to try to bring both the wire and contact up to the proper temperature at the same time. If you are soldering a "big honking" spade lug (as Tom Andry might say) to a comparatively smaller wire, you need to spend more time heating the spade than the wire. So you'd wet the iron and pre-heat the spade until it gets close, and then heat both wire and spade and apply solder to the joint, not just the wire. Applying solder to just the wire gives you a blob, not the concave look you want. It takes practice to time things out.

 

[jneutron]

For the current high temp solders, the tin-silver eutectic with either antimony or copper, I have found it advantageous to modify the procedure a bit.

For most of my soldering with wires from #2 to about #24, I will generally use the molten solder to heat the parts. I put the tip in contact, but do not wait for the parts to heat up via tip contact. Instead, I allow the solder to pool a tad between the tip and the work, and when the parts are ready, they suck the metal into the joint.

This method does two things. It limits the temp excursion of the parts prior to the flux contacting the surfaces( for cored solder), and it starts the process by heating the parts using material that is at 221 degrees C.

It takes some experimenting to get a feel for how to do this properly, but once you've learned the technique, you can get very good joints while limiting the amount of oxidation the flux has to combat, and it is better for the plastics in the vicinity.

Oh, and I really like tsteve's comment about not using solder to bridge the conductors...that cannot be stressed enough. (had the people in Geneva followed this rule, they would not be in the middle of a 26 million dollar repair..)

Cheers, John

 

[lsiberian]

For the current high temp solders, the tin-silver eutectic with either antimony or copper, I have found it advantageous to modify the procedure a bit.

For most of my soldering with wires from #2 to about #24, I will generally use the molten solder to heat the parts. I put the tip in contact, but do not wait for the parts to heat up via tip contact. Instead, I allow the solder to pool a tad between the tip and the work, and when the parts are ready, they suck the metal into the joint.

This method does two things. It limits the temp excursion of the parts prior to the flux contacting the surfaces( for cored solder), and it starts the process by heating the parts using material that is at 221 degrees C.

It takes some experimenting to get a feel for how to do this properly, but once you've learned the technique, you can get very good joints while limiting the amount of oxidation the flux has to combat, and it is better for the plastics in the vicinity.

Oh, and I really like tsteve's comment about not using solder to bridge the conductors...that cannot be stressed enough. (had the people in Geneva followed this rule, they would not be in the middle of a 26 million dollar repair..)

Cheers, John

What your saying is the two ends should make physical contact and then the solder should be added?

 

[jneutron]

What your saying is the two ends should make physical contact and then the solder should be added?

Yes. As tsteves stated, the physical connection should be made first (where possible). In the picture provided, the wire was folded back on itself through a loop, this is a physical connection. To break that by pulling is far more difficult than a simple lap joint...a lap joint relies on the shear strength of the solder alloy, and tin-lead undergoes ductile creep..

Cheers, John

 

[j_garcia]

My metals instructor's comment was "heat the work", meaning you need to bring the items to be soldered up to temperature for the solder to flow correctly. If you don't, you are just melting solder and dropping onto your items, creating a cold solder joint where the solder is not making good contact with either of the items to be soldered - this is not only a weaker bond, it also isn't good for electrical conductivity. You have to be careful when doing this with jacketed wire though, because there is a lot of wire generally and the wire wants to conduct that heat through itself; if you heat it too much it could melt the jacket. This is one of those techniques you need to learn to know when it is working and when it is not.

Like jneutron said, and that is the way I work as well, I will get the solder to flow and then wick it up into the joint first - this seems to get it started well so that the solder will then flow when you heat that joint again and touch the solder to it.

If you didn't get it already: a physical connection is the way to start if at all possible!!!! It will be that much stronger.

 

[jneutron]

My metals instructor's comment was "heat the work", meaning you need to bring the items to be soldered up to temperature for the solder to flow correctly. If you don't, you are just melting solder and dropping onto your items, creating a cold solder joint where the solder is not making good contact with either of the items to be soldered - this is not only a weaker bond, it also isn't good for electrical conductivity.

For the most part, your instructor is correct.

That said, let's talk about the differences, and why my process is better. For discussion only, I will refer to "you" as in not me..

You heat the parts before the flux has left the core, since there has been no melting of the solder in order to release the flux.

I do not heat and further oxidize the metals until the flux has been released. So my method limits the amount of time the metals are hot and in oxygen.

You have a tip that will force the work to greatly exceed the melt temperature of the solder...for tin/silver, that is 221 C, you will bring the work well beyond that temperature before the flux and metal can cover the base materials. Remember, when the base metal exceeds an upper temp (flux dependent), the flux will burn instead of clearing the oxides and remaining in place to prevent oxygen from hitting the metal.

You bring the base metal well above 221C. If you are soldering to a small pushbutton which has epoxied terminals out the back, you will compromise the switch because the epoxy will debond from the terminal and flux will be drawn into the switch. (I had to autopsy lots of C & K switches for this).

The real thing your instructor is doing, is forcing you to make sure the work gets to the adequate temperature to melt the solder and form the correct intermetallics. This can be a real concern, and you rightly point out the possibility of cold solder joints.

As I pointed out with my method, once the molten solder had heated the base metals sufficiently, then the actual joint will occur. An experienced solderer will certainly be knowledgeable in watching the process to make sure cold joints do not occur.

I taught lots of guys here how to do it properly, and so far, there have not been any catastrophic failures due to cold joints.

If your instructor would like to learn about it, let me know, I'd be happy to detail it more for him(her) offline.

Cheers, John

ps..ahhh, an edit.. seems you do what I do also... but your cautions are absolutely correct, good points..

 

[lsiberian]

For the most part, your instructor is correct.

That said, let's talk about the differences, and why my process is better. For discussion only, I will refer to "you" as in not me..

You heat the parts before the flux has left the core, since there has been no melting of the solder in order to release the flux.

I do not heat and further oxidize the metals until the flux has been released. So my method limits the amount of time the metals are hot and in oxygen.

You have a tip that will force the work to greatly exceed the melt temperature of the solder...for tin/silver, that is 221 C, you will bring the work well beyond that temperature before the flux and metal can cover the base materials. Remember, when the base metal exceeds an upper temp (flux dependent), the flux will burn instead of clearing the oxides and remaining in place to prevent oxygen from hitting the metal.

You bring the base metal well above 221C. If you are soldering to a small pushbutton which has epoxied terminals out the back, you will compromise the switch because the epoxy will debond from the terminal and flux will be drawn into the switch. (I had to autopsy lots of C & K switches for this).

The real thing your instructor is doing, is forcing you to make sure the work gets to the adequate temperature to melt the solder and form the correct intermetallics. This can be a real concern, and you rightly point out the possibility of cold solder joints.

As I pointed out with my method, once the molten solder had heated the base metals sufficiently, then the actual joint will occur. An experienced solderer will certainly be knowledgeable in watching the process to make sure cold joints do not occur.

I taught lots of guys here how to do it properly, and so far, there have not been any catastrophic failures due to cold joints.

If your instructor would like to learn about it, let me know, I'd be happy to detail it more for him(her) offline.

Cheers, John

ps..ahhh, an edit.. seems you do what I do also... but your cautions are absolutely correct, good points..

So you apply the solder to the two sides and let it flow as it heats up.

I've never actually soldered before. I want to learn since I should know how.

 

[jneutron]

So you apply the solder to the two sides and let it flow as it heats up.

I've never actually soldered before. I want to learn since I should know how.

I generally push the solder in between the iron tip and the wire. The solder will melt against the tip first, and the blob (technical term) of liquid metal won't adhere to the wires at first...but when the wires come to a high enough temp, then it will bond.

If you choose to go with the normal practice, then all you do is push the solder end in between the two wires or wire and terminal, and when it comes up, it'll melt in.

The standard way is typically good enough for tin lead, I find my way more suited for problem joints and/or tin-silver.

Cheers, John

 

[AJinFLA]

Hi John,

So this is where you're hanging out these days eh?
I can't PM you until >5 posts, so here's #2

cheers,

AJ

 

[jneutron]

Hi John,

So this is where you're hanging out these days eh?
I can't PM you until >5 posts, so here's #2

cheers,

AJ

Hey there AJ.

Actually, I'm not hanging out anywhere, my plate has about 100 meters of business piled up, so have no energy or time left for audio anything. Given the recent debacle in Geneva, and the easy way it could (and should) have been avoided, my curiosity was peaked by the subject matter. I was pleased with the writing style and content.

If not for the specific topic, I would not have posted.

Cheers, John