What's the common name for an adhesive thermal spacer? - Page 1
Forum section: electronics / projects

author: Psi
author_rank: Super Contributor
timestamp: September 27, 2022, 11:22:03 am
content: I'm looking for a thermal spacer. Something to go between the PCB and the plastics case and help transfer some of the PCB heat to the case.Does anyone know what those things are called. It's hard to search when you get 100's of results for thermal tape.The stuff I'm looking for is 3-5mm thick, adhesive on both sides, and a little soft/squishy.Obviously it doesn't need to be crazy high thermal conductivity since it's only coupling to plastic.

author: eutectique
author_rank: Frequent Contributor
timestamp: September 27, 2022, 11:41:19 am
content: Thermal pad? Add "cpu" to your search request.

author: nali
author_rank: Frequent Contributor
timestamp: September 27, 2022, 11:55:26 am
content: Thermal interface sheet or thermal gap filler?

author: Someone
author_rank: Super Contributor
timestamp: September 27, 2022, 12:57:24 pm
content: "gap pad®"that's one brand name for it, but you'll find the others from there. Picking the right softness is a bit of an art.

author: ajb
author_rank: Super Contributor
timestamp: September 28, 2022, 04:40:48 pm
content: 'Silpad' is a genericized name, not necessarily adhesive. "Thermal Interface Material" is the most generic, that would encompass pastes and sheets of all kinds. Most distributors will throw any kind of TIM sheets into one category, so you'd have to filter for the characteristics you want (adhesive on both sides, thickness, durometer, etc) from there.Quote from: Psi on September 27, 2022, 11:22:03 amI'd be skeptical of the benefit of this at all, really. Are you trying to better couple heat from the whole PCB to the outside world, or from specific part(s)? If you have specific parts, then you might be better served using a heat spreader so that you're conducting through a larger area of the plastic case than just a thermal pad (the heat spreader can even be the PCB, if you design it with that as a priority, although a solid sheet of aluminum at 1-2mm thick would probably be more effective). If you're trying to couple the whole PCB I guess a TIM pad could have meaningful improvement, but you'd want to do the math. Using a large squishy pad is tricky, because the amount of force required to hit a certain level of deflection in the thickness goes up with area, so you end up needing a lot of force to compress the pad if it's not already very close to the finished thickness. Making the TIM pad the primary mechanical constraint would address that problem, but could complicate other aspects of the mechanical design, for example if you have connectors that need to line up with holes in the case.

author: coromonadalix
author_rank: Super Contributor
timestamp: September 28, 2022, 05:12:00 pm
content: You have the thermal gap fillers, they can be thicks as 1/2 inch more or less, it depend of your needs

author: exmadscientist
author_rank: Frequent Contributor
timestamp: September 28, 2022, 05:32:30 pm
content: Quote from: Someone on September 27, 2022, 12:57:24 pmYep, they're gap pads around here. At least for the ones that fill in any reasonable distance.Our experience is that unless you are about to go to production and it's penny pinching time, don't skimp on these. The more premium ones (but not necessarily most expensive!) really are better.