Tinning Best Practice?

nicholasjames

A question for those who have hardware experience.

Back during my hands-on, CTS training days, I recall being instructed to never tin the wires going into a phoenix block, be it audio or, most pertinent to me, control. The justification for this was a soldered end is very rigid and may only make contact on a few small points. However I've also heard that tinning helps prevent loose strands and ensures all strands are touching.

What's everyone else's experience? Are there any resources, particularly industry standards, I could point to?

catalino

Even here at my place of business, the opinion is split between tinning and not. I always tin my wires no matter what, as it prevents frays and shorts. Use a good malleable solder, I've found that tin solder doesn't work as well as lead-based solder, but YMMV based on local laws and regulations and personal preference.

Andrew G Welker

From what I understand, tinned wires don't hold their shape and will deform over time under the pressure of the screw terminal. The only time I tin my wires is when I am actually soldering a connector on the wire.

See this PDF from Extron.

vining

Typically with electroncs eutectic solder is preffered 63/37 because it has a shorter plastic state. That's state between wet and solid and by minimizing the plastic state you minimize cold solder joints.

Code really only applies (afaik) to soldering or sweating of copper used on potable water supplies.

Surface contact area at the connection point vs the change in the skin affect... Hmmmm? To much to think about so i'd go tin less and just shove the stranded wires in and call it a day.

Of course if you'r worried about connact area you could flaten the wire prior to tinning. Since cold solder joint aren't an issue here using 60/40 would be a bit softer.

I don't tin myself but maybe if excessive oxidation was an issue in some corrosive environment i might but i'd have to re-evaluate why i have terminations in such conditions in the first place.

DHawthorne

Depends on the wire for me. Most of the time, I don't bother. But once in a while you run into a wire that has a lot of really fine conductors that are impossible to reign in. When there is any chance of strands causing a short because I can't manage them, *then* I tin it.

regallion

No one uses ferrules?

annuello

I prefer to not tin them. The biggest issue I come across is how much insulation has been stripped. Obviously too much insulation removal can cause the conductors to short if the cable is flexed.

Not enough insulation removal causes the clamp to hold onto the insulation, with the wire conductor only "tickling" the conductive part of the cage clamp. The electrical connection becomes intermittent with thermal changes. I've seen this several times on AMX power supplies, from the factory. A quick chop and re-terminate fixes the issue.

What I do these days is chop the end of the cable with side cutters, insert the fully-insulated cable into the cage clamp to get a visual on how much insulation to strip, and then only remove what is necessary. I twist the strands to keep them from straying, though I know some cables are less cooperative than others.

Another consideration for me is that if solder smoke (or a sandwich toaster) pushes a dusty smoke alarm beyond its threshold it will result in a building evacuation (hundreds of people), a visit from several fire trucks, and a bill of a few thousand dollars per truck. So for me, soldering on-site is a balance between necessity (with associated hassle of setting up fume-management equipment) and alternative ways of joining cables. I've come to love screw terminal strips.

Roger McLean
Swinburne University

Jimweir192

Bootlace Ferrules everytime

pdabrowski

The explanation I got from my tech workshop lecturer (over 15 years ago) was that tinning conductors to be secured by a screw block (or similar terminal) allowed the malleable solder between the copper strands to compress and change their position over time - particularly in high mechanical stress situations (motor vehicles for example).

When this happens you no longer have a "gas-tight" connection and as a result you can get corrosion between the tinned conductors and the terminal. A gas-tight connection can be in place when the copper is tinned on a screw down terminal block but the malleable solder is the reason why there won't be a guaranteed gas-tight connection over a long period of time.

The same is true when using punch-down IDC blocks for data and telephone applications, the action of the teeth in the IDC connection not only pierces the insulation, it also creates a gas-tight connection between the copper conductor and terminal block - another reason why I get angry seeing techs not use the correct tools on the job.

Thorleifur

Ferrules here also. Never tin.

pcuser

Ferrules

Must concur, Bootlace Ferrules are the way to go...
A decent crimp tool should be used to crimp the ferrule. The tool I personally use works for different size ferrules.

kennethk

As Andrew G Welker says, i dont solder bacause of deformation over time.

The same goes for Ferruls.
Ferrules only if crimp tool crimps "flat", else nothing.
"Round crimped" Ferruls also tends to deformate over time

vining

I just ordered some of these to try out, we'll see....

http://www.clrtec.com/index.php?route=product/product&path=160&product_id=2470

The planet wave products make dressing out a rack extremely simple and very neat but there's just something about the way they work that make me nervous but I can't say I've had any issues with the RCA, BNC, etc ends.