Weak glue recommendations needed!

[John HaineParticipant @johnhaine32865]

I need to assemble a tiny pcb carrying some opto components into a machined brass block so it won’t come out in normal use but can be removed, for example by gentle heat or using a non corrosive solvent, later if any of the components fail. The kind of stuff that is used to lock preset potentiometer could be the kind of thing. Any recommendations please?

[peter1972Participant @peter1972]

What are you doing about insulalation between the PCB and the brass?

Depending on how the PCB sits in the brass block, consider using small pieces of sheet foam, perhaps closed-cell foam. That’s very unconventional but you should then be able to simply pull the PCB out of the block if necessary.

[Paul LousickParticipant @paullousick59116]

Adhesive used in a hot glue gun can be softened by gentle heat

[Grindstone CowboyParticipant @grindstonecowboy]

A couple of strategically placed blobs of contact adhesive (lust left to dry, not coating both surfaces as you would usually do) would hold it firm, but would peel off either surface relatively easily.

Rob

[duncan webster 1Participant @duncanwebster1]

Double sided sticky tape if you have a reasonable area

[Michael GilliganParticipant @michaelgilligan61133]

Shellac seems to fit the job-description very nicely !

MichaelG.

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Send me your postal address if you would like a little, John.

[Kiwi BlokeParticipant @kiwibloke62605]

All the suggestions to date seem pretty good to me. To possibly induce decision paralysis, here are some more: a blob of oil paint or nail varnish, BluTac, blob of silicone sealant (neutral cure), rubber solution (puncture repair kit), endless possibilities…

The light alloy reed plates in accordions are held to their wooden supporting structures by a mixture of beeswax, rosin and oil. They are intended to be removable. Proportions are not critical, approx. equal weights of wax and rosin, with a dash of vegetable oil. Easier, and probably OK, although less resilient and less sticky, would be just beeswax. It’s less brittle than ordinary candle wax.

[John HaineParticipant @johnhaine32865]

Thanks all.  Shellac or nail varnish sound the best approach – I can just soak the assembly in solvent to release if needed.

[Michael GilliganParticipant @michaelgilligan61133]

Shellac liquifies at about 75° C … which would also make your board re-positionable.

https://en.wikipedia.org/wiki/Shellac#Properties

MichaelG.

[John HaineParticipant @johnhaine32865]

Positioning isn’t a problem in fact as the PCB fits in place very snugly and just needs lightly holding, but the heat removal option might be useful.

Thanks again everyone for the suggestions.

[bernard towersParticipant @bernardtowers37738]

4 spots in the corners with a low temp glue gun

[Robert Atkinson 2Participant @robertatkinson2]

I’d second Kiwi Bloke’s suggestion of silicone sealant (neutral cure to prevent copper corrosion). Good positive hold, wide temperature range, can fill gaps but is easilly peelled or cut off when required.

Robert.

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