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Seen hot-air-gunning, super-gluing, epoxy-gluing, plastic-taping, other-taping, --. Super-gluing joints did not look good as you need acetone to remove it!

  1. is epoxy gluing better substitute for soldering?
  2. when to use such substitutes?
  3. are they really substitutes or just bad habit?
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6 Answers 6

Nothing you listed is a substitute for soldering, they are all things you can use for physical attachment or insulating but are not things to use for making an electrically conductive connection.

Hot-air-gunning, do you mean hot air soldering or maybe given the nature of the other things mentioned heat shrink tubing?

super glue (cyanoacrylate glue) is a good insulator. i have heard of people using it to provide extra hold on wire wrap boards. its not doing the job of solder though, its not providing the electrical connection but rather just keeping it from coming unwrapped.

Every type of epoxy i've used has been an insulator although there appear to be some that are conductive and may be useful in specific situations. (Thanks Michael/Jeanne)

Plastic tape is an insulator.

Duct tape's core is a conductor, but the coating and glue on the tape is an insulator.

I would never use any of these in place of solder.

I do use some of them as insulators though. For instance if I have soldered wires coming off a pcb i'll plop hot-glue or epoxy over the connection to glue the wire to the PCB and remove stress from the solder connection.

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Actually there are plenty of conductive epoxies available - they are usually made with a high silver content and tend to be quite expensive. They are generally only used when soldering is no good for some other reason (such as the risk of heat damage to other components). –  Michael Kohne Jun 24 '10 at 0:45
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Conductive epoxy is good for repairing lifted traces. –  Jeanne Pindar Jun 24 '10 at 1:19
    
thanks michael / jeanne, updated my answer to mention conductive epoxy. –  Mark Jun 26 '10 at 19:47
  • Wire-wrapping is a substitute for soldering but wire-wrap supplies can get very expensive unless you buy in very large volumes or happen to find a surplus deal.

  • You could also crimp the wires together. There are terminals called butt splices. You could insert multiple wires into the terminal and then crimp. These are meant for thinner stranded wires but could work for solid leads. Butt splices have two ends but there may be some sort of small ferule you could purchase.

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Dead right about the high price. Long looked for cheap wire wrapping tool but haven't found. Got recommend expensive products such as "Slit-N-Wrap® Tools: P160-1B, P184-1 -- by Vector Electronics" and Radio Shack's cheap wire wrap thing (only US). So had to do it myself with wooden stick having 22AWG-30AWG all way through, cheap and reusable :) –  hhh Jun 25 '10 at 10:26

Adhesives aren't going to provide any electrical conductivity, and aren't likely to work well with metal surfaces since these don't tend to be very porous.

If you have two wires that are well twisted together, covering the joint with heat shrink tubing or tape can insulate the otherwise bare metal and prevent shorts (essentially the same job as a 'wire nut'), but has no other advantage. Oxygen and humidity can generally still get into the joint, and these are what eventually will degrade the connection.

If you are joining wires, or components with wire leads, then wire nuts, crimp-on splices, or screw-down connections (like barrier strips) will work OK, but aren't really suitable for fiddly little items. These methods are more suited for old-school vacuum tube and relay technology.

For small scale semiconductors and low-wattage passives, you really can't beat solder. It provides a conductive, oxygen-excluding bond between even flat metal surfaces. If the problem is concern about lead, there are lead-free solders that flow at somewhat higher temperatures but are not beyond hobby level tools.

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2: when to use such substitutes?

When you need to attach things together electrically and you can't solder. Or your afraid to solder. Or the device will be local to a person's skin, in which case you shouldn't use solder due to heavy metals which can affect a person's health.

3: are they really substitutes or just bad habit?

Technical answer: Depends how reliable your connection needs to be and the conditions its going to be in and length of time it needs to work.

I used black electrical tape to connect resistor leads to wires in a custom Ghostbusters backpack. The electrical tape was sufficiently sticky and the connections worked well enough that it survived two evenings of my roommate running around begging candy off of people (a fair amount of torture, IMHO), and still worked when it came back to the apartment. Which was all it needed to do. So it was a decent substitute, I think.

Would you do that in a production unit to sell? I wouldn't do that even if my job didn't depend on it. But for roommate during crazy weekend? Eh, it works.

Real answer: Really, though, its a bad habit used by lazy people who need to improve their soldering techniques... Don't do what I did.

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  1. is epoxy gluing better substitute for soldering?

A technique with ball grid array is "under filling" that uses epoxy mixture, the paragrahp is not crystal clear about the mixture. It seems to mean that soldering and epoxy-gluing are used almost simultaneously: you solder first then use epoxy glue to attack mechanical stress issues but "epoxy soldering" would be misleading as the expoxy gluing is no substitute. There may still be cases with epoxy-rosin-lead-mixtures(speculation, plz, attack).

Mechanical stress issues can be overcome by bonding the devices to the board through a process called "under filling", which injects an epoxy mixture under the device after it is soldered to the PCB, effectively gluing the BGA device to the PCB. There are several types of under fill materials in use with differing properties relative to workability and thermal transfer.

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If you are talking about attachment for electrical interconnection, soldering or strong mechanical metal-to-metal contact (think sockets, tightly wrapped wire-wrap, or wire-nuts) are the two most common reliable methods.

Sometimes, adhesives are used to temporarily tack the components in place under they are soldered in. It's important that these adhesives are not too rigid - you want some "give" so that the chip can be removed for rework.

Now, if you're talking about soldering for, say, building up your mechanical enclosures, then there are definitely other methods that you can use. Soldering is clearly good for solderable metal pieces. Cementing is good for compatible plastics. And for quick mcguyvering, duct tape is your friend! :)

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