Attaching PCB to wood - Page 1
Forum section: electronics / projects

author: lutkeveld
author_rank: Regular Contributor
timestamp: July 03, 2020, 10:42:29 am
content: I have a capacitive touch board that I need to attach to wood.Screws are not an option.Hot glue does not seem like the most reliable option.What would be a good option? Silicone, epoxy, double sided tape?Thickness must be <1mm, otherwise the capacitive touch wont register anymore.Does anybody have experience with this?

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: July 03, 2020, 12:43:27 pm
content: I think the question boils down to what sticks to wood. The board is no problem. I've built various things with hot glue and it works well. There are various types of hot glue, some of which need more hot than others. IMO, the hotter pro versions are better. Another great thing is 3M VHB tape. Usually very reliable.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 03, 2020, 02:20:43 pm
content: silicon caulk ?

author: Benta
author_rank: Super Contributor
timestamp: July 03, 2020, 04:32:38 pm
content: 24h Epoxy is the thing (you know, the type with two equally sized tubes).You'll need to fix the two pieces together mechanically and put the joint under pressure during curing. It's a good idea to add food-wrap foil between fixture and assembly, otherwise you may end up with a larger assembly than you planned for.Preheat your oven to 100 C, chuck the assembly in and wait 30 min.Done.(Don't tell your wife about the oven part).

author: ejeffrey
author_rank: Super Contributor
timestamp: July 03, 2020, 06:22:44 pm
content: QuoteI don't understand. Presumably you are gluing the non-touch sensor side to the wood?It would also be good to understand why screws aren't an option and what kind of wood. Are you gluing to a thin piece of plywood with a cutout for a down-facing sensor?Anyway, my first choice would also be standard long-set epoxy. Hot glue is tricky because it doesn't stay liquid very long so it is hard to get a thin and uniform layer inside the bond. You would probably have to make do with a few spots around the edge. Epoxy on the other hand gives you ample time to position the work pieces, secure them, clean up squeeze out and so on. Watch out for flow. Epoxy has a gotcha that if you use heat to cure it gets substantially less viscous when first heated. This helps it form a good bond as it flows into narrower areas and can permeate the wood fibers a bit more, but it can also flow where you don't want it.Hot glue is a quick and dirty option, and it might work OK. It has the advantage that you can hold it in place while it sets, and it doesn't become less viscous at any point.

author: Bud
author_rank: Super Contributor
timestamp: July 03, 2020, 06:57:39 pm
content: Why 24hr epoxy? Five min epoxy works a charm.

author: Benta
author_rank: Super Contributor
timestamp: July 03, 2020, 08:51:41 pm
content: Quote from: Bud on July 03, 2020, 06:57:39 pmYou missed the heating part. This makes the epoxy very fluid and increases the strength exponentially. 5 min epoxy doesn't work that way and is not very strong in comparison.I regularly use 24h epoxy and heat to 180 C for curing (which is not appropriate with wood) and achieve joints that are unbreakable.

author: phil from seattle
author_rank: Super Contributor
timestamp: July 03, 2020, 09:49:44 pm
content: I'm confused about the thickness part. Cap sense would happen on the top of the pcb, the glue and wood would be on the bottom. Just about any adhesive will work with wood but I'd use epoxy. I would get a thin acrylic or polycarbonate sheet to cover it if that's what you are thinking.And by the way, there is no need to heat cure the epoxy - it will have plenty of strength to hold an unstressed board.