All Purpose non-Conductive Adhesive? - Page 1
Forum section: electronics / general

author: PhysicsDude55
author_rank: Contributor
timestamp: October 14, 2018, 05:59:32 pm
content: I'm looking for some all-purpose non-conductive adhesive to use for my electronics projects. Preferably the same cloudy schmoo (some call it hot snot?) that's smeared over loose componenets in manufactured electronics. I tried doing some searches, and couldn't find much. Tried searching the usual places I buy electronic components from, but all I can really find is thermal paste and thermal conductive epoxy.I don't need it to be thermally conductive. I just want to squirt some goo on electrical components, connections, wires, etc. that's non-conductive and readily available/cheap.I've tried hot glue with little luck. Is normal silicone caulk any good for this purpose?

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 14, 2018, 06:09:55 pm
content: A lot of what I find smeared over electronics is hot glue. I have used it pretty successfully myself. As with all adhesives surface type and surface preparation matters more than adhesive type. Oily surfaces will stop most adhesives, including hot glue. There are several varieties of hot glue, you might try experimenting with others. Also, since hot glues flow into place fairly well but are viscous enough to hold their shape you can often achieve a mechanical bond even if adhesion is not successful.RTVs also work pretty well, given adequate surface prep. Here there is even more variety than in hot glue, and the ones that smell like acetic acid on curing are not recommended for electronics (though I have used them with some success.)

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 14, 2018, 06:12:40 pm
content: I think you're looking for Silastic and its non name brand brethren.https://en.m.wikipedia.org/wiki/Silastic

author: cowana
author_rank: Frequent Contributor
timestamp: October 14, 2018, 07:59:56 pm
content: If going with RTV, make sure you get a type designed for use with electronics. The standard 'bathroom sealant' grade are made of acetic acid, and will cause long term corrosion if they get in contact with copper or component legs.

author: rdl
author_rank: Super Contributor
timestamp: October 14, 2018, 10:01:58 pm
content: I built a small power supply board many years ago. I used a board mounted transformer and to insulate the mains AC traces I covered them with a small rectangle of thin polystyrene plastic glued down with Loctite RTV silicone glue - the acetic acid smelling kind. I didn't actually use the board and tossed it in a drawer. About 4 or 5 years later, after hearing of the potential problems with that type of adhesive, I removed the plastic sheet and inspected the traces, but I didn't see any evidence of corrosion.

author: PhysicsDude55
author_rank: Contributor
timestamp: October 15, 2018, 05:01:05 am
content: Thanks for the replies. I used hot glue in a project where I had wires soldered to very small traces on an existing PCB, and the wires kept popping off while I put everything back into the case. After applying the hot glue, it very obviously was a decent conductor and wrecked havoc on my arduino inputs.I ordered some "704 Adhesive Silicone Rubber" from china for cheap. The electronics silicone adhesive I found from US suppliers or Amazon prime was like $7-10 per tube, this stuff is $2 per tube. We'll see how it works out.

author: tooki
author_rank: Super Contributor
timestamp: October 15, 2018, 01:44:01 pm
content: No way hot melt glue is a good conductor. If it were, thousands of DIY projects and countless millions of commercial gadgets would be malfunctioning. Whatever happened with your Arduino project, it wasn't because of hot melt conductivity.

author: wraper
author_rank: Unknown
timestamp: October 15, 2018, 02:00:24 pm
content: Quote from: CatalinaWOW on October 14, 2018, 06:09:55 pmIn power electronics where such adhesives are used the most I barely ever seen a hot glue used. And the reason for that if pretty obvious. And many times I've seen hot melt, it already came off but I never seen this happen to silicone.

author: Zero999
author_rank: Super Contributor
timestamp: October 15, 2018, 03:59:04 pm
content: Quote from: PhysicsDude55 on October 15, 2018, 05:01:05 amAs mentioned above hot melt glue is a good insulator. In fact most adhesives are good electrical insulators, apart from the water based ones. The fault with your Arduino project was not caused by the glue.QuoteThere's a reason why electronics silicone adhesive is more expensive than the cheap stuff. It's because it doesn't emit acetic acid, vinegar, whilst curing, which can cause corrosion problems, especially in soldered connections. What's worse is the acid emitted can evaporate and condense on other parts, causing more corrosion.

author: wraper
author_rank: Unknown
timestamp: October 15, 2018, 04:13:05 pm
content: Quote from: Hero999 on October 15, 2018, 03:59:04 pmThat's acetoxy type (vinegar smell). But you can also buy usual neutral cure RTV silicone (actually there are several types of those, like alkoxy) in hardware store as well. It's just there is no spec/guarantee about it's conductivity, dielectric constant, dielectric strength, dissipation factor.

author: GeoffreyF
author_rank: Regular Contributor
timestamp: October 15, 2018, 06:01:04 pm
content: Why do you want to do this? Manufactured products have different requirements than home brew ones. Manufacturers may wish to stabilize the components for shipping. They may wish to prevent tampering for warranty reasons. They may find it less costly to glue something down than to provide a mechanical fixation for it. Of course there are still reasons to use glue but less than a manufacturer has.What you did not mention when you said "non conductive" is what the dielectric of the glue should be or whether it might prevent a part from dissipating heat properly. Not thermally conductive is one thing - a "Blanket" is another. In general, my thinking is that less is best.If it's home brew you may not know when you might want to make a change - that's another difference with manufactured stuff.

author: thm_w
author_rank: Super Contributor
timestamp: October 15, 2018, 09:48:54 pm
content: Quote from: wraper on October 15, 2018, 04:13:05 pmYeah for DIY electronics get the Silicone type 2 from home depot/etc, price is the same from what I saw as the acetoxy cure (type 1). White or clear is available.https://www.homedepot.com/p/GE-Silicone-2-2-8-oz-Clear-Window-and-Door-Caulk-GE500-3TG/100179996https://images.homedepot-static.com/catalog/pdfImages/66/664fb1c9-6aed-43dc-88d7-3a10bff81124.pdf(no acetic acid)