Using epoxy to add mechanical strength to solder joints

[timhowell]

I'm just finishing up an amp build (Tom Christiansen's Novar Spud) and have a couple of connections that don't have any mechanical strength, but are only held together by solder. In particular, one of the connections between the power transformer and the IEC power entry module had to be made with the power transformer lead laying flat against the tab on the power entry module instead of going through the hole in the tab. Is there any reason not to put some epoxy on the joint to give it some additional mechanical strength? I know the solder joint is solid, and I'm not concerned about the electrical connection, but I would like to make it more robust mechanically. I do also realize that using epoxy will mean I will likely need to replace the entire power entry module if I need to change the joint for some reason.

I'd appreciate any feedback,

--TWH

 

[Miles Prower]

That shouldn't be necessary, and as you pointed out, makes things messy if you need to change it later.

 

[KatieandDad]

You should always be able to connect two contacts together with a piece of wire to insure against mechanical shock even if the piece of wire is very short.

 

[analog_sa]

Using wire wrap wire even without a proper tool will help a lot. Still going to be messy when unsoldering, but at least without the toxic fumes.

 

[Mooly]

Commercial products sometimes use a kind hard whitish compound, like silicon rubber but less pliable in what I assume is some kind of stress relieving exercise. Used to see it a lot on mains switches and so on in the days when TV's and the like were a repairable item. Also used where wires enter and leave PCB's.

Don't know what it is or what it was called though.

I wouldn't use epoxy though. For normal diy gear you shouldn't need anthing like this imo.

 

[AndrewT]

For mains connections, you should consider where the broken loose end could spring off to touch.

If there is a risk of the loose end touching some other component then supplementary mechanical fixing is required.

Can the wire end be mechanically fixed, before soldering?
Can the wire end be wrapped in such a way that a form of mechanical fixing is achieved? And then soldered.

I have used strands from flexible cable to wire wrap around the two parallel leadouts from a pair of capacitors. Then soldered.

 

[Bibliophile]

Heat shrink tube would also help and provide some electrical safety as well.

 

[Mooly]

Good idea, I'll second that suggestion.

 

[M Gregg]

If you are using,

Epoxy to strengthen a joint something is wrong. Wire wrap and /or solder, heat shrink, crimp spade male female are all acceptable. Epoxy to fix a part OK..to strengthen a joint???

Regards
M. Gregg

 

[DF96]

Wherever possible a joint should be mechanically sound before you apply solder. That means wires wrapped around tags, and if possible squeezed so they grip. Tack soldering is fine for a short-term prototype, or during debugging.

 

[lexx21]

What exactly do you think that your amp will be doing that the wire would fly off? When you solder two pieces of wire together, providing that you have a good solder joint, they are not going to come apart.

Now if your amp had an after burner on it and delta wings....... that could be a different matter entirely..... But just sitting there on your table playing music and not pulling excessive G forces that would peel your lips back over the top of your head, I think that you will be ok. In fact... I'm pretty sure of it.

 

[AndrewT]

Vibration makes wire fatigue and eventually they crack.
That's when wires spring free.

 

[kevinkr]

Secure the wiring with wire ties or lacing if vibration is a concern; tube damage and tubes falling out of sockets is a much more likely scenario.

What if you need to rework down the road, toxic fumes from burning epoxy could constitute more than a nuisance, but an actual hazard.