Crimp Alone -vs- Crimp + Solder

[Warpspeed]

If you use the right lug, with the correct cable, and use the exact crimping die for the job, there is nothing better.
Used in the automotive, and aerospace industries, and by the power utilities and military for decades. Its a time proven technique.

That does not mean "Bubba" crushing something flat with his big hammer is going to make a totally reliable crimp joint.

If you don't have all the right matching stuff for the job, the results may be at best questionable.
Do the best you can, and then if in doubt, solder it as well.

 

[Frick]

If you use the right lug, with the correct cable, and use the exact crimping die for the job, there is nothing better.
Used in the automotive, and aerospace industries, and by the power utilities and military for decades. Its a time proven technique.

That does not mean "Bubba" crushing something flat with his big hammer is going to make a totally reliable crimp joint.

If you don't have all the right matching stuff for the job, the results may be at best questionable.
Do the best you can, and then if in doubt, solder it as well.

For severe environments as this thread is, a perfect crimp is only as good as two I disable metals touching. The copper softens and the pressure lessons. Air and moisture migrate in. Solder creates a bond, better than touching. the White paper posted from trojan is a case study of an initial result, after a few months of extreme environments it’s worse.

 

[Warpspeed]

You could say that all plugs and sockets, switches, and bolted connections are "just touching" yet they do still work, and work reliably.

The trick is to keep the metal to metal joint clean, and free of corrosion, moisture and oxidation.

Soldering certainly does that.
And so do does an extreme pressure crimp joint, where the malleable metal actually flows and fills any voids, keeping out the contaminants.

Fifty years ago 100% of all cable joints in the telephone industry were soldered. Back then underground cables used lead sheaths and paper insulation.
Today its all thermoplastic insulation and various types of crimp and compression joints. Not a soldered joint anywhere, and the telephones still work.
You will not find too many soldered joints in aircraft either these days, and they are fanatical about reliability.

 

[Checkthisout]

You could say that all plugs and sockets, switches, and bolted connections are "just touching" yet they do still work, and work reliably.

The trick is to keep the metal to metal joint clean, and free of corrosion, moisture and oxidation.

Soldering certainly does that.
And so do does an extreme pressure crimp joint, where the malleable metal actually flows and fills any voids, keeping out the contaminants.

Fifty years ago 100% of all cable joints in the telephone industry were soldered. Back then underground cables used lead sheaths and paper insulation.
Today its all thermoplastic insulation and various types of crimp and compression joints. Not a soldered joint anywhere, and the telephones still work.

I like the terms "malleable" and "flow".

These are much better descriptions of a crimped connection over the term "cold weld".

Marine shrink wrap is critical to both solder and crimped joints when it comes to keeping out corrosion.

I do however notice that the oem's just crimp their cables and do not apply shrink wrap.


Going to guess material Quality plays a large role in corrosion abatement.

 

[Warpspeed]

Metal fatigue is well understood these days, and any type of connection should have some kind of reinforcing or strain relief such as shrink wrap, or some kind of rubber boot or cable gland to discourage bending right at the joint.

Its all common industry practice,and any properly designed equipment just follows good engineering principles.

If corrosion is going to be an obvious threat, the whole joint should be protected, all the nasty stuff should not be able to get anywhere near any cable joint. Potting for example, conformal coatings, or IP67 boxes with waterproof cable entries, lots of solutions often used together.

 

[JeepHammer]

I've heard this debate for nearly 50 years, and for 50 years I've seen with my own eyes what happens to electrical connections Vs. structural connections getting confused...

I've been off grid for over 30 years, and that long building industal machines.

Small barrel type crimp terminals will benifit 100% of the time from crimp AND silver bearing electrical solder (low temp melt point).

The raw copper ends of the wire stick through the barrel, raw copper exposed when stripped to attach the terminal end...

You CAN NOT squeeze a small barrel terminal enough to bond the copper to the terminal. Both are too thin, not enough mass, you will simply mash the copper enough to squish out (become plastic) out of the crimp tool.

Thermal cycling (expansion/contraction) will loosen the barrel of the terminal on the wire 100% of the time.

The ONLY way to permanently ELECTRICALLY bond the wire to the terminal is proper silver bearing solder.

The high vibration/aircraft application argument doesn't fly for this application. Wiring harness in commercial aircraft are ROUTINELY REPLACED.

YOU will never be working with 400 cycle AC current. YOUR wiring will never have to survive a lightening strike while airborne... Use your heads about application...

Your solar system isn't using 17,000 volt surge rated wire with fireproof teflon insulation, you won't be using a precisely fitting crimp tool, and your crimp tool will never be inspected on gaging equipment, checked for precise application of force, ect.

Even if it were the proper aircraft certified tool, and you were educated to use it correctly, you ARE NOT using precisely sized, specific alloy wire that tool requires, or the specific alloy, specific sized terminals the tool requires to make proper aircraft authorized connections.

Use copper terminals on copper wire, give them a good mechanical crimp that DOESN'T unduely stress/distort the terminal improperly, then cover the air gaps that WILL happen with silver bearing solder, use your own heat shrink for environmental protection.

Different lugs, tools and rules for heavy LUGS (not little terminals) and heavy copper conductors.

There is enough mass for a heavy bonding mechanical crimp with Lugs & Cables.

That crimp DOES NOT negate the air space/bare copper issues that silver bearing solder or actual silver solder solves.

Tinning exposed copper is environmental protection. The silver makes formally air spaces into conductive connections. Silver is MORE CONDUCTIVE than the copper, so it's a common sense thing.

This IS NOT an either/or question. Mechanical crimp, then solder, both, not either/or.

Nothing beats silver solder (high temp) or silver bearing electrical solder (low temp) to close up air gaps, protect copper, make better electrical connection.

Solder is in NO WAY a replacment for mechanical compression (crimp).
A solder joint CAN overheat, that will both damage the solder, and potentially let the wire/cable LOOSEN in the connection.

Mechanical connection, THEN solder for filling in air spaces, increase conductivity, and seal out oxygen/moisture (corrosives).

Don't treat it like an 'Either/Or' thing. Air in a bald tire doesn't mean the tire is 'Good'...

 

[Ryujin]

I've heard this debate for nearly 50 years, and for 50 years I've seen with my own eyes what happens to electrical connections Vs. structural connections getting confused...

I've been off grid for over 30 years, and that long building industal machines.

Small barrel type crimp terminals will benifit 100% of the time from crimp AND silver bearing electrical solder (low temp melt point).

The raw copper ends of the wire stick through the barrel, raw copper exposed when stripped to attach the terminal end...

You CAN NOT squeeze a small barrel terminal enough to bond the copper to the terminal. Both are too thin, not enough mass, you will simply mash the copper enough to squish out (become plastic) out of the crimp tool.

Thermal cycling (expansion/contraction) will loosen the barrel of the terminal on the wire 100% of the time.

The ONLY way to permanently ELECTRICALLY bond the wire to the terminal is proper silver bearing solder.

The high vibration/aircraft application argument doesn't fly for this application. Wiring harness in commercial aircraft are ROUTINELY REPLACED.

YOU will never be working with 400 cycle AC current. YOUR wiring will never have to survive a lightening strike while airborne... Use your heads about application...

Your solar system isn't using 17,000 volt surge rated wire with fireproof teflon insulation, you won't be using a precisely fitting crimp tool, and your crimp tool will never be inspected on gaging equipment, checked for precise application of force, ect.

Even if it were the proper aircraft certified tool, and you were educated to use it correctly, you ARE NOT using precisely sized, specific alloy wire that tool requires, or the specific alloy, specific sized terminals the tool requires to make proper aircraft authorized connections.

Use copper terminals on copper wire, give them a good mechanical crimp that DOESN'T unduely stress/distort the terminal improperly, then cover the air gaps that WILL happen with silver bearing solder, use your own heat shrink for environmental protection.

Different lugs, tools and rules for heavy LUGS (not little terminals) and heavy copper conductors.

There is enough mass for a heavy bonding mechanical crimp with Lugs & Cables.

That crimp DOES NOT negate the air space/bare copper issues that silver bearing solder or actual silver solder solves.

Tinning exposed copper is environmental protection. The silver makes formally air spaces into conductive connections. Silver is MORE CONDUCTIVE than the copper, so it's a common sense thing.

This IS NOT an either/or question. Mechanical crimp, then solder, both, not either/or.

Nothing beats silver solder (high temp) or silver bearing electrical solder (low temp) to close up air gaps, protect copper, make better electrical connection.

Solder is in NO WAY a replacment for mechanical compression (crimp).
A solder joint CAN overheat, that will both damage the solder, and potentially let the wire/cable LOOSEN in the connection.

Mechanical connection, THEN solder for filling in air spaces, increase conductivity, and seal out oxygen/moisture (corrosives).

Don't treat it like an 'Either/Or' thing. Air in a bald tire doesn't mean the tire is 'Good'...

Thank you!
If I'm reading you correctly both small and large lugs benefit from soldering after crimping.
What is the best method to Solder after crimping? For both small and large crimps?

 

[JeepHammer]

Thank you!
If I'm reading you correctly both small and large lugs benefit from soldering after crimping.
What is the best method to Solder after crimping? For both small and large crimps?

'BEST' would be dipping the conductor and terminal in pure silver, allowing it to reach temps that let the silver flow in.

Small wires silver bearing electrical solder. Low temperatures let the solder flow without damaging the conductor insulation.

You can quite easily 'Tin' (coat) exposed wire and terminal. Any damage to insulation can be covered with heat shrink to reinforce the insulation.

I do the easiest way, which is the common ways. Soldering iron, or little torch (see crack-head jet torches from the convenience stores).

I also do it the industral way, electro-magnetic induction heating. If I'm doing a lot of termination at the workbench, I'm not above using a solder pot.

If it's BIG conductors, of course those take a lot more heat. Hand held propane torch (think plumber's torch) or electro-magnetic induction.

Since a propane torch won't reach the temp required for pure silver (proper silver soldering), oxygen fed torch set, fuel & oxygen bottles, or electro-magnetic induction.

Don't underestimate electro-magnetic induction, it will reduce steel to liquid, so copper & silver don't stand a chance. You can VAPORIZE aluminum...

If you do heavy lugs, Buss bars, etc, search for an electric 'Nut Buster', 'Bolt Buster' or 'Rust Buster'.

Hand held unit with different induction coils, and with silver soldering paste (silver flakes suspended in resin) or brazing paste (copper/bronze flakes suspended in resin) you can properly silver solder and braze things quite easily, no torch required.

It's also damned handy for its labeled purpose, busting rust on bolts/nuts. You can heat thw target without a big flame trying to destroy everything around the targeted bolt or solder/braze point.

 

[Warpspeed]

Thank you!
If I'm reading you correctly both small and large lugs benefit from soldering after crimping.
What is the best method to Solder after crimping? For both small and large crimps?

Small lugs, just a normal soldering iron.
For larger lugs sometimes two soldering irons !
On rare occasions for really huge lugs, the kitchen gas stove plus a large soldering iron has worked.

 

[12VoltInstalls]

I seldom solder anymore. Typically not necessary.

But I will crimp everything I can. Solder is for PCB’s or after crimping.

I’ve got a 25-year history of crimping terminals. Bare terminals. No boat wiring failures I’m aware of. Then waterproof the connection.

I don’t work on saltwater boats but I have worked on ??hundreds? a thousand? utility trailers in salted roads Vermont and New Hampshire. For vibration reasons I don’t solder there either. But I take pains to watertight all joints. Even then there can be a failure but not very often.

 

[Ryujin]

'BEST' would be dipping the conductor and terminal in pure silver, allowing it to reach temps that let the silver flow in.

Small wires silver bearing electrical solder. Low temperatures let the solder flow without damaging the conductor insulation.

You can quite easily 'Tin' (coat) exposed wire and terminal. Any damage to insulation can be covered with heat shrink to reinforce the insulation.

I do the easiest way, which is the common ways. Soldering iron, or little torch (see crack-head jet torches from the convenience stores).

I also do it the industral way, electro-magnetic induction heating. If I'm doing a lot of termination at the workbench, I'm not above using a solder pot.

If it's BIG conductors, of course those take a lot more heat. Hand held propane torch (think plumber's torch) or electro-magnetic induction.

Since a propane torch won't reach the temp required for pure silver (proper silver soldering), oxygen fed torch set, fuel & oxygen bottles, or electro-magnetic induction.

Don't underestimate electro-magnetic induction, it will reduce steel to liquid, so copper & silver don't stand a chance. You can VAPORIZE aluminum...

If you do heavy lugs, Buss bars, etc, search for an electric 'Nut Buster', 'Bolt Buster' or 'Rust Buster'.

Hand held unit with different induction coils, and with silver soldering paste (silver flakes suspended in resin) or brazing paste (copper/bronze flakes suspended in resin) you can properly silver solder and braze things quite easily, no torch required.

It's also damned handy for its labeled purpose, busting rust on bolts/nuts. You can heat thw target without a big flame trying to destroy everything around the targeted bolt or solder/braze point.

So crimp and just put the lug vertical and heat the lug and cable with the solder at their junction? I'm more not understanding the technique to solder after crimping.

 

[octal_ip]

So crimp and just put the lug vertical and heat the lug and cable with the solder at their junction? I'm more not understanding the technique to solder after crimping.

I'm with you here - I've tried the gas torch method before, and it did a lot of damage to the plating on the lug and insulation on the wire before the wire was hot enough to wick any solder. The high temperatures also caused the copper (both wire and lug) to oxidise very quickly, ruining the whole joint and preventing any further adhesion from the solder.

I'm obviously Doing It Wrong?
I'm assuming 3AWG is far too large to solder with an iron?

 

[Warpspeed]

You need to apply a lot of heat, not excessive temperature.
A really big soldering iron, with enough thermal mass, heated hot enough to do the job is better than a small very high temperature welding torch.

If the lump of copper on the end of the iron has enough copper mass, applying it for just a few seconds will get the job done without melting anything but the solder. The stranded wire sucks up the solder into the lug like a dry sponge.

These images are a bit extreme, but then we are talking about soldering some pretty extreme lugs.

 

[Ryujin]

I guess i'm just looking for a video showing a good technique to get solder into a crimped connection. All my googling just gets crimped vs solder.

 

[Warpspeed]

Soldering big jobs need not be any different to soldering small jobs.
Its just that the tools to do it need to be scaled up appropriately.

I have bought several high wattage plumbers soldering irons over the years, they are not cheap, and all seem to not last very long, the elements usually go open circuit. A big copper bit heated within a flame is a bit "stone age" but its entirely practical.
The miserly way is to buy a big chunk of really heavy copper round or rectangular bar and make your own.

We are not usually doing this very often, so something primitive but effective, is entirely practical.

 

[Samsonite801]

You need to apply a lot of heat, not excessive temperature.
A really big soldering iron, with enough thermal mass, heated hot enough to do the job is better than a small very high temperature welding torch.

If the lump of copper on the end of the iron has enough copper mass, applying it for just a few seconds will get the job done without melting anything but the solder. The stranded wire sucks up the solder into the lug like a dry sponge.

These images are a bit extreme, but then we are talking about soldering some pretty extreme lugs.

Yeah, and what I always found when I used to soldier big lugs (depending on your preference), is you want to get the heat into the ring terminal and get it up to temperature quickly (so it doesn't have time to soak too much heat up the cable, which can lead to sucking soldier up the cable, making it stiff), and the biggest mistake I see people make is they put the torch flame too close so they're not in the hottest part of the flame, to the point where it is stubborn to get heat up very quickly.

I found to hold the torch (assuming a normal plumber's propane torch), with the white tip of the flame, not in too close so the white point isn't really into the ring terminal, holding back so the hottest part of the flame is actually concentrating into the terminal, it shouldn't take as long to get it up to temp, and once the soldier flows in, get the heat off of it just as quick, and start blowing air on it to cool it down. That's just what I got to the point of doing with more experience.

Practice on a few and you can figure out quickly how the flame/torch tip distance makes a big difference.

 

[JeepHammer]

So crimp and just put the lug vertical and heat the lug and cable with the solder at their junction? I'm more not understanding the technique to solder after crimping.

A solder pot is just what it sounds like, a moment pot of solder. Just dunking won't do it, you have to leave the CRIMPED terminal and wire in long enough it heats so the solder will flow into the open spaces of the joint.

This is a technique used in huge, industral connections, or when a lot of wire splices are being soldered together. It's not used by home hobbiests.

It's not often used in small, automotive gage wire simply because keeping a solder pot hot is a pain in the butt, and its not what you want to do with outdoor, roof top, or hanging upside down job sites.

On small joints, CRIMP, heat the TERMINAL until solder flows into the joint. This will be roll or stick, silver bearing electrical solder.

Soldering iron or jet torch lighter, doesn't take much to get the terminal hot enough to melt the solder into the joint.

Bigger terminals, like cable lugs, again, CRIMP, then solder. Bigger lugs take more heat, so plumbers torch or induction heating.

Full on pure silver soldering, oxy/gas fuel torch or induction. The plumbers torch won't do it.

Pure silver is by far the hardest to do. High heat, you can quite easily under heat or overheat the silver.
When you get it right, it's stupid strong, and as discussed before, silver is a better conductor of electricity than copper.

 

[JeepHammer]

Yeah, and what I always found when I used to soldier big lugs (depending on your preference), is you want to get the heat into the ring terminal and get it up to temperature quickly (so it doesn't have time to soak too much heat up the cable, which can lead to sucking soldier up the cable, making it stiff), and the biggest mistake I see people make is they put the torch flame too close so they're not in the hottest part of the flame, to the point where it is stubborn to get heat up very quickly.

I found to hold the torch (assuming a normal plumber's propane torch), with the white tip of the flame, not in too close so the white point isn't really into the ring terminal, holding back so the hottest part of the flame is actually concentrating into the terminal, it shouldn't take as long to get it up to temp, and once the soldier flows in, get the heat off of it just as quick, and start blowing air on it to cool it down. That's just what I got to the point of doing with more experience.

Practice on a few and you can figure out quickly how the flame/torch tip distance makes a big difference.

The easiest way I've found to do little open barrel terminals is bend the wire so the terminal/inside barrel is facing up, you can see the copper where you cut it.

Apply heat to the terminal, dab the solder on the ends of the wire.

Try a few times, remove heat and dab, apply more heat, remove heat an dab, when the solder flows you'll know it instantly.

Give it a little solder, when you see silver at the copper on the other side of the barrel (insulation side) STOP.

A few tries and you will get the hang quickly.

Now when you heat shrink the wire & terminal barrel, the exposed ends aren't exposed anymore, you have a layer of solder between moisture bare copper where you stripped the wire, but that doesn't excuse you from using heat shrink to keep water out of the insulation jacket...

I make it as hard as humanly possible for water to get at the copper. Silver solder, heat shrink, drip loops so water doesn't ride the wire right into you joint, etc.

I HONESTLY don't want intermittent issues, the hardest to find. A total failure is easier to track...

Never, ever, under any circumstances use one of those ice pick test probes and break the insulation! (From experience)

Nothing like looking for a failure INSIDE the insulation jacket... bring one of those to my job site and you have two choices... throw it away immedately, or leave.

It's like a monkey with a machinegun, sooner or later they just can't resist and will pull the trigger... 5 years later I'm standing in the pouring rain, 100° heat, or freezing cold trying to find the intermittent problem some idiot with an ice pick created... (service calls NEVER happen on really nice days, Murphy's law)

 

[Johno1066]

As an apprentice in 1960, the days of paper and lead cables, I watched some guys building a heavy distribution panel for heavy loads. when it came to the heavy wiring the supervisor wanted the lugs soldered to the cable and the electricians wanted to crimp. So they soldered the tinned lug to the cable, clamped the lug in a vice pulled heavily on the cable and managed to pull the cable out of the soldered lugs. They then crimped the lugs and were unable to pull the cable free from the lug. End of the story was that the supervisor made them solder and then crimp the lugs. At that time heat shrink still had not been invented and the ends were just well taped up.

 

[12VoltInstalls]

supervisor made them solder and then crimp the lugs

That’s backwards and actually damages the connection. And with a good crimp is actually difficult to get solder to flow through the crimp. Usually the tinning on the terminal is what flows.