Beginner at soldering, how good or bad are these joints - Page 1
Forum section: electronics / beginners

author: broo0d
author_rank: Newbie
timestamp: February 19, 2016, 10:40:38 am
content: Hi everyone,Yesterday i began to practice soldering on some wires.After little practice I've come up with solders that has residue and some of it has a dark brown residue, most of it can not be cleaned with a brush and a cleanerThis is a 15 AWG wire.This is a 12 AWG speaker wire

author: brabus
author_rank: Frequent Contributor
timestamp: February 19, 2016, 12:06:48 pm
content: Hello,The soldering itself is actually not bad, as long as mechanical sturdiness and electrical conductivity are guaranteed. Flux residues bring nothing good nor bad in this case. But if you found difficult to remove them even with a cleaner (what did you use?), I'd rather start thinking about the quality of your solder.I would worry about soldering and flux residues only if we start talking about a PCB. In that case things are pretty different! I suggest you to start practicing on a cheap and simple kit (eBay has a lot to offer!), good solder and good iron, and off you go!Regarding soldering cables head-to-head, I would rather discuss the effectiveness of this technique at all. Soldering inhibits the natural flexibility of the cable, making it more fragile and prone to breaking in some environments (happened in many cases to me, until I started using exclusively crimped connectors).The insulating plastic is also altered, becoming harder and eventually even brittle.I would rather crimp a good pair of connectors, or use a screw terminal instead.Let's see some photos of your first PCB!

author: Adam60
author_rank: Regular Contributor
timestamp: February 19, 2016, 01:31:37 pm
content: When you are doing "Western Union type joints, you want to end up with about 1/2" of exposed joint which requires roughly 3/4" of exposed copper on each wire before starting. When you wrap them, the key is to make sure that the strands are tightly wrapped. After applying the solder, you should be able to run your fingers over the joint without catching any skin on it. Your first joint is okay with solder but the ends are sticking out enough to catch skin and the wire looks dirty, hence the dark flux. Make sure the wire is clean before soldering and you won't have this problem. The second joint is much better but it is a little long and you may have had the heat on it a little too long.For your first attempt, bravo, well done. Practice, practice, practice...,.,,

author: AndyC_772
author_rank: Super Contributor
timestamp: February 19, 2016, 01:43:27 pm
content: When I join two wires together, I rarely twist them together first.Instead, I'll twist and tin each wire individually, but then to join them, I place the two ends side by side and apply some extra solder to form the joint.The advantage is that the two wires never have to twist relative to each other (which isn't possible if they're attached to fixed objects), and it's very easy to undo the joint just by re-heating.Your joint is probably stronger, but since the wire will break before the solder joint in both cases, I don't see that as a problem.

author: Brumby
author_rank: Unknown
timestamp: February 19, 2016, 01:59:45 pm
content: Quote from: AndyC_772 on February 19, 2016, 01:43:27 pmI've never had that problem, but my technique might be slightly different to yours.

author: Ian.M
author_rank: Super Contributor
timestamp: February 19, 2016, 02:26:46 pm
content: A good western union splice can withstand a considerable tensile load before you solder it. The 'classic' version is for solid wire and only has a 3/4 turn twist in the middle then the ends are each wrapped 5 times round the standing part continuing in the same direction as the twist. For stranded wire, I prefer to pass the strands of each through the other so they interleave rather than using a twist in the middle. Wrap the ends round the standing part working outwards from the middle in opposite directions.When you solder it the wrapping turns should be fully wetted, but the solder should not be allowed to run any significant distance beyond the ends of the joint. Also the insulation should not be damaged or distorted, which may require keeping it cool with a strip of wet cloth held in place with a clothespeg or similar.Done correctly, the joint should be close to cylindrical, of comparable diameter to the wire insulation, and it should be possible to coax the insulation back into place right up to the joint. It can then easily be covered neatly with self-amalgamating tape or heatshrink for insulation, after dressing the ends of any strands that are sticking out slightly with a file so they don't puncture the new insulation.For thin wires, lightly tinning them, laying the ends parallel, then wrapping tightly with a single strand of tinned copper wire to form a single closely wound layer over the whole joint before soldering can be easier than doing a proper western union splice. Its nowhere near as strong but at least it wont fall apart if the wire overheats due to excess current.If you are using good quality clean wire and fluxcore solder, the joint should be bright with no flux residue except at the very ends even before you clean it. If there is muck bubbling up in the middle of the joint, the wire was probably dirty and may not have tinned right through.If there is any doubt about the cleanliness of the strands, abrade them the best you can (e.g. fan them, pinch in a green pan scourer and pull the strands through it, then repeat turning the wire slightly a few times) and dip the wire end in liquid R or RMA flux before making the splice.

author: Cerebus
author_rank: Super Contributor
timestamp: February 19, 2016, 03:25:42 pm
content: Quote from: AndyC_772 on February 19, 2016, 01:43:27 pmI take it from that, that you mean that the whole joint is stronger than the whole cable which would be correct (or at least 99.9% of the time).It's worth pointing out two additional things.Firstly just for the sake of disambiguation. The wire will be stronger than the solder. That is, given a single strand each of copper wire and solder wire of the same size, the copper wire will have greater mechanical strength and greater fatigue strength. This gets important in any joint subject to vibration or flexing - the solder will break first and this can lead to some painful to find intermittent faults.Secondly, the most common place for a joint like in the photograph to fail is where the stranded copper joins the soldered mass. It's a very good idea to provide mechanical support around the whole of a joint like this. Heat shrink sleeving is a common choice.

author: KL27x
author_rank: Super Contributor
timestamp: February 20, 2016, 12:34:24 am
content: QuoteWhich is important when tensile strength is important. Such as for suspended power lines, or a wire that you are going to pull through a conduit.For smaller wires that are not put under such conditions, the fatigue between the joint and free wire is usually the main area of concern. Hence, I usually solder them like AndyC.QuoteI'm not so sure you wouldn't want the wire to fall apart if it reaches over 260C!I will do something similar when splicing a coaxial power (not RF) wire. Trim and fold the outer strands back over the outer insulation, and then wrap them with a piece of small buss wire. Tin. Then use an insulated jumper wire to joint the two outer conductors together. That makes things neat and the joints for the two conductors don't overlap.Another trick I use that is reminiscent is to use string and hot glue to add rigidity and insulation, particularly if I don't have the right size heatshrink. Usually after putting on some electrical tape (definitely good idea to use proper tape where indicated!), I'll dab some glue over the area to be reinforced, wrap a piece of porous string around the wire/connection so it covers the taped area, and continue until satisfied. Even if exposed to solvent, it doesn't come off until you really try pretty hard to remove it with a knife, because the string is porous and is locked to itself. The tape doesn't come unraveled at the ends or become sticky, and it adds some bulk and strain relief.

author: broo0d
author_rank: Newbie
timestamp: February 23, 2016, 05:13:22 pm
content: Thank you all of guys for your help, i really appreciate it.I am doing a sound system upgrade on my car.This is the amp rack I've built. Still in progress.It is my first time to do anything like this. Researched a lot before doing it.All the wires terminated with a crimp connectors and set in place with screw terminals.My question about soldering is just about connecting two wires together.brabus point out to me another method i forget about. Which is crimping.Do you think using a good quality butt connectors is a good idea in a car and can stand vibrations more than solder joint ? less resistance and reliability in mind.The wire (16 AWG) will carry little amperage (around 0.5A) and will be supported in place the entire length by zip ties.I still need to solder small wire to speaker terminals and attach quick disconnect connectors to that wire.

author: Ian.M
author_rank: Super Contributor
timestamp: February 23, 2016, 05:27:30 pm
content: Crimp terminals and connectors made with a good quality ratchet crimping tool are extremely reliable, far more than a solder joint to stranded wire in an automotive environment. However if you use the wrong tool or it has the wrong size dies for the crimps you are using the result can easily be less reliable than simply twisting and taping the joint! Its quite possible that the speaker terminals will accept push-on female blade connectors that you can crimp directly to the speaker wires.

author: Cerebus
author_rank: Super Contributor
timestamp: February 23, 2016, 07:10:50 pm
content: Quote from: Ian.M on February 23, 2016, 05:27:30 pmThe termination of choice in the automotive environment is definitely a properly executed crimp. The key there isproperly executedwhich you quite rightly point out doesn't happen "if you use the wrong tool or it has the wrong size dies for the crimps you are using".Time for one of my standard soap-box speeches. There are cheap tools and there are inexpensive tools.The cheap tools cost little. Inexpensive tools can be costly - in the case of good crimp tools, "You want how ******* much?". The cheap tools may have little initial cost but you'll have to replace them far more often that you'd like, they'll do work that is fair to poor and you'll spend more time trying to get jobs right or redoing work that wasn't up to scratch. In the long run cheap tools can be expensive.Good tools cost more money, sometimes a lot more money. But they last a long time, they fit, they apply the right pressure in the right place, the job goes right the first time, you don't waste time and money reworking things. In the long run good tools can be inexpensive.Consider the humble screwdriver. You can pick them up for pence or you can spend some serious money on some. I've got a set of screwdrivers that I bought more than thirty odd years ago. They were not cheap and I made a point of getting every size I could. Over thirty years later they are almost as good as new, will last out at least my lifetime and I think I've probably only stripped the heads on less than 10 screws out of tens of thousands that I've inserted and removed in the time I've owned them.I would strongly advise that you always buy the very best tools that you can afford. Learn to use them properly, take good care of them and they will repay the initial expenditure several times over.Crimp tools are a special category. The prices asked for good quality crimp tools are eye-watering and even more painful when you realize that every different type of connector you need dies for will cost you another £50-100 GBP. It will be very tempting to get the cheaper alternatives. DON'T. I've used good (and sadly expensive) crimp tools and cheap ones. The cheap ones really, genuinely aren't worth having - when I've been forced to use them I've had to rework at least 50% of the crimps made. By contrast, the scarily expensive varietyjust workand I've had to rework a tiny fraction of the joints I've made with them - perhaps one or two in every thousand.TheotherIan M

author: broo0d
author_rank: Newbie
timestamp: February 23, 2016, 07:15:01 pm
content: Quote from: Ian.M on February 23, 2016, 05:27:30 pmThat is what I've concluded after search but wanted to be sure.Speaker has push on terminals, the problem is no one will fit nicely. Ill take a look at that.

author: broo0d
author_rank: Newbie
timestamp: February 23, 2016, 07:31:47 pm
content: Quote from: Cerebus on February 23, 2016, 07:10:50 pmI am trying to get the right tools for the job. Ive purchased a high quality connectors made in EU and US.Started with no tools at all, bought tools that cost me maybe the same amount of getting the setup installed in a shop, maybe more.but i know in the long run i would be better of buying the right tools and learn how to properly do things.I think i will look for a good crimper that have more sizes than mine.

author: broo0d
author_rank: Newbie
timestamp: February 23, 2016, 08:22:49 pm
content: Ive tested the connectors i have. they fit perfectly and have the correct wire size.I am very pleased now.I bought the connectors months ago when i didn't know about sizes so I've purchased different sizes.