Best Marine Soldering Practices

[noelex 77]

There are plenty of threads about soldering v crimping. Let’s just say both can produce great marine electrical joints, but even if you prefer crimping, soldering is a good skill to have. There are some joints and repairs that can only be done via soldering.

Boat electrical systems are becoming far more sophisticated. Techniques that produced perfectly acceptable results a decade ago are not necessarily satisfactory with the demands and high currents used on modern boats.

Soldering technique is all important, but this is very difficult to teach via forum posts. So I wanted to share a couple of posts about soldering equipment. Most boat owners try to solder with terrible equipment. With skill this can still produce acceptable results but good equipment does produce much better joints and as I have indicated above I think it is time to raise the standards boat electrical work.

[noelex 77]

Solder:

The ideal solder for boat work is Leaded 63/37 with RMA flux. Preferably a known, quality brand.

Almost everyone using leaded solder on a boat will be using the much cheaper, older style, 60/40 solder, usually a no name brand, with an unknown flux.

63/37 solder is better. It has a higher tin content. The main advantage is this is a eutectic solder. Basically this means the solder only has one melting temperature. 60/40 solder has a temperature range. Once it is hot enough to melt, it has to cool down to a lower temperature before it solidifies. An joint movement during this solidification process will result in a poor joint. The instant temperature transition between a liquid and solid of 63/37 solder means there is less risk of a dry joint, particularly on a boat where soldering is not always in ideal conditions on a nice steady bench.

There are other advantages. The melting point of 63/37 solder is slightly lower, which reduces the risk of damaging components and wire insulation. 63/37 also produces a slightly stronger joint than 60/40.

The next consideration is the flux used. The flux cleans the metal surface so the solder flows. It is basically impossible to solder without flux. The flux is most commonly incorporated into the solder wire itself, but you can use flux in paste form as well. The flux works by attacking the wire surface to remove the oxidation, but this also means the most aggressive fluxes are corrosive. Not ideal in a marine environment. Many cheap solders have reasonably aggressive fluxes, because this makes the solder easier to use. The flux can (and should be) cleaned away from the wire when you have finished soldering, but in a marine environment using as mild a flux as possible is better. The mildest fluxes are rosin based, but there are several grades of flux within the rosin family. The mildest is R followed by RMA (rosin mildly active) flux. The next slightly more aggressive flux is RA (rosin active). Following that there are many more very aggressive flux combinations. These can be useful for older, very oxidised wires, but you need to clean the joint carefully after using these.

Good solder wire will list the type of flux it contains. A simple solution is to buy 63/37 RMA solder and some tins of more aggressive flux in paste form for the more difficult cases.

[GordMay]

How about: https://www.all-spec.com/Manufacture...150-9702-16600

[thomm225]

Also, if you use heat shrink on your solder connection, be sure to use a heat gun rather than a lighter when working in the bilge area especially if you have cleaned your connection with electrical cleaner

I was looking around at work for a heat gun before I resoldered my new bilge pump wires one afternoon a few years ago. One of the tech's said just use a lighter. I wasn't thinking about the dangers of open flames near electrical cleaner and remembered the lighters I had onboard for my propane hot plate (this would be one of the few times I used a lighter on heat shrink instead of a heat gun)

So I put on the heat shrink and soldered the connections. I then sprayed electrical cleaner on the first connection and then moved the heat shrink over it and shrunk it down with the lighter. On the second, I sprayed a bit more cleaner on the connection, moved the heat shrink down and as I lit the lighter there seemed to be a fog down there in the air which immediately went Whoof!

So I knew my face had been burnt a bit but I was afraid to look in the mirror. I touched my forehead and felt the hair at the top crumble from where it was singed. I was afraid my face was going to look like one of those cartoon characters that had a bomb blowup close to him.

The damage ended up looking like I had spent too much time on the beach without suntan lotion or in a tanning bed set on max. Plus, all my hair that had hung down over my forehead was also gone. My lighter hand was burned the worst. I had to put toothpaste on it so I could sleep

The gas in my boat is just aft of the bilge area. I was very lucky as were the rest of the boats at the marina

As far as the solder, I use whatever type I see first depending on which bench I "borrow" the soldering equipment from. My main thing is to have a nice clean soldering iron when I solder

[noelex 77]

Originally Posted by GordMay

How about: https://www.all-spec.com/Manufacture...150-9702-16600

Good point Gord. I should have mentioned 62/36/2 solder. It is preferred by some to 63/37.

The addition of silver slightly further improves the joint strength. The advantages are otherwise very similar to 63/37. Both I think are a better, but a more expensive, option than 60/40.

Kester is great solder brand. They also make 63/37 solder and have a bewildering number of flux options. It is more expensive than the no-name brands, but you know what you are getting.

[thomm225]

If you don't have a lot of experience with soldering, it may be best just to crimp the wires together.

If you cannot recognize a cold solder joint, you may want to stay with crimping.

My background was a one week course in soldering back in the 1970's then I was able to perfect it over the next ten years or so doing jobs from soldering large wires to installing small flat pack chips with a Pace Station with foot operated desoldering air tool.

Today though there is very little soldering in the electronics field because everything is so small

[KTP]

Originally Posted by thomm225

Today though there is very little soldering in the electronics field because everything is so small

It is still soldering, it is just done using machines, solder pastes, masks, and BGA packages which have little balls of solder on the hundreds of contact pads.

I have soldered as small as a TQFP144 and 0402 resistors but I did use a binocular microscope.

After using a Weller for decades with the magnetic tip, it finally wore out and I had to replace it. Reading that Weller no longer makes a good version of this, I went with this Japanese soldering iron, which looks like a furby but actually is very high quality and very good tip control. I liked it so much I bought one for the boat and one for my home lab.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[S/V Illusion]

Originally Posted by thomm225

If you don't have a lot of experience with soldering, it may be best just to crimp the wires together.

If you cannot recognize a cold solder joint, you may want to stay with crimping.

It's pretty simple to recognize a cold solder joint. Conversely, it's impossible to determine if you have a bad crimp connection without destructive testing.

Consequently, it is often preferable to solder rather than crimp connections.


The common mistake people make with soldered connections is failure to ensure a good mechanical connection which can fail from vibration. Solder isn't a substitute for mechanical connection. Both are required. And it's easy to also ensure cables don't move, bend or break by using common sense.

[thomm225]

Originally Posted by KTP

It is still soldering, it is just done using machines, solder pastes, masks, and BGA packages which have little balls of solder on the hundreds of contact pads.

I have soldered as small as a TQFP144 and 0402 resistors but I did use a binocular microscope.

After using a Weller for decades with the magnetic tip, it finally wore out and I had to replace it. Reading that Weller no longer makes a good version of this, I went with this Japanese soldering iron, which looks like a furby but actually is very high quality and very good tip control. I liked it so much I bought one for the boat and one for my home lab.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Yeah, there is still soldering, but what I meant was on everyday circuit board repairs. Replacing chips etc. Troubleshooting the CPU board and replacing a bad chip or a power supply and just replacing the bridge rectifier or other failed component

That's simply unheard of these days out (CPU motherboard repairs) in the field.......rather than at the manufacturer.

Back in the day, we bought tips 10 at a time of various sizes. That is tips for the irons and tips for the solder sucker. (solder extraction tools)

Standard equipment then (and now on most of our benches) was a Pace Station with foot operated desoldering tool.

https://www.paceworldwide.com/produc...-rework-system

https://www.youtube.com/watch?v=e8KRPFOD1RE

[GordMay]

Originally Posted by S/V Illusion

It's pretty simple to recognize a cold solder joint. Conversely, it's impossible to determine if you have a bad crimp connection without destructive testing...

In a good joint, the solder should be wetted to the metal, not beaded up, and also shiny, not cloudy/dull.

However, the only way, that works perfectly, in identifying a bad or good joint is a functional test, under strong vibration and at high and low temperatures.

A 'Cold Joint' is one where the solder did not melt completely. It is often characterized by a rough or lumpy surface. Cold joints are unreliable. The solder bond will be poor and the cracks may develop in the joint over time.
Cold joints can usually be repaired by simply re-heating the joint with a hot iron until the solder flows. Many cold joints (such as the one pictured) also suffer from too much solder. The excess solder can usually be drawn-off with the tip of the iron.
A properly pre-heated soldering iron with sufficient power will help prevent cold joints.

Much More (with pic’s) ➥ https://learn.adafruit.com/adafruit-...ommon-problems

[Lake-Effect]

Originally Posted by noelex 77

Boat electrical systems are becoming far more sophisticated. Techniques that produced perfectly acceptable results a decade ago are not necessarily satisfactory with the demands and high currents used on modern boats.

I know you're expecting this: where on a boat is it advisable to use solder for making a high-current connection? I don't know of one, nor of any situation where soldering would produce a better high-current connection than mechanical means.


ABYC and all that...


I don't have any issues with carefully soldering lower current and signal connections, as long as all the mechanical problems caused by soldering (brittleness, loss of flexibility) have been addressed.

[GordMay]

Originally Posted by Lake-Effect

I know you're expecting this: where on a boat is it advisable to use solder for making a high-current connection? I don't know of one, nor of any situation where soldering would produce a better high-current connection than mechanical means.

ABYC and all that...

I don't have any issues with carefully soldering lower current and signal connections, as long as all the mechanical problems caused by soldering (brittleness, loss of flexibility) have been addressed.

Indeed.
However, I'd encourage noelex to continue this tutorial.

[Dymaxion]

Biggest cause of dry solder joints is corrosion on wires you're trying to join. If the copper is dull brown, black or even greenish the odds of a dry joint are good. Flux will get through mild "tarnish" but you'll need to clean off with a bit of fine sandpaper to get the heavier stuff off and see some real copper colour before you solder. You can keep cutting back the wire of course, looking for fresh clean copper, maybe having to splice in a length eventually.

I have a cordless soldering iron that I've never had much success with, comments/recs for a decent version would be great.

There are also propane torch soldering kits, which I've never tried. Use caveats about bilge fumes using them I'd say. In desperation I've used a cheap kitchen knife heated cherry red by a propane torch, worked "ok" but fiddly.

[Rough Magic]

What about the use of lead free solder? Like the type used in plumbing?

[Lake-Effect]

Portable soldering irons!


I have a couple butane ones; my favourite is over 15 years old. I couldn't find a picture of it but it's similar to this:

... except that mine uses the same screw-in butane cartridges used in portable curling irons.



Advantages:

• reasonably fast heating
• enough heat to solder lugs onto AWG#12 wire (after crimping of course)
• fuel cartridges last a decently long time and are easy to find (Meet me in the beauty section...)

I have recently acquired a 12v soldering iron; it's not as hot as the butane. I'm still learning its capabilities. It accepts different tips that are readily available for other Chinese low-wattage irons.