PCB warmer using a cheap electric burner - should I use some alum/copper plate? - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: October 07, 2015, 07:51:11 pm
content: Hi Everyone,Sometimes I need to use hot air and warming a pcb to 150 deg C makes it easier to work with. I've got a pid controller and a cheap single burner (not inductive). The burner does have a solid top (not wires), but using a thermal camera you can see that its heat is uneven. Would something like a aluminum or copper plate be a good heat evener/spreader? Which is better copper or aluminum? Aluminum is cheaper, would twice as thick aluminum be better than copper? Also, what would you use to connect the plate to the burner? Some sort of heat transfer adhesive?Thanks!

author: Siwastaja
author_rank: Super Contributor
timestamp: October 07, 2015, 08:16:47 pm
content: Copper is better per volume, but aluminium is clearly better when you measure it per price or per weight, which is why aluminium is used most of the time for this kind of purpose. It's also easier to source. So go get some thick aluminium sheet.You can use standard thermal paste and physically fasten the things together. Another option is thermal glue, which is like thermal paste but will provide strong enough bond that you don't need any other way to fasten the pieces. Whichever you use, only use an extremely thin layer, just enough to fill any microscopic air gaps.

author: alank2
author_rank: Super Contributor
timestamp: October 07, 2015, 08:25:30 pm
content: How thick do you think is good? 1/4" ?

author: Siwastaja
author_rank: Super Contributor
timestamp: October 07, 2015, 08:35:07 pm
content: It depends on how large the area is and how uneven the heat is to begin with, but without any numbers and even seeing it, I could imagine that 1/4" thick aluminium sheet would work great for a PCB warmer up to something like 5" x 5" PCB size.

author: alank2
author_rank: Super Contributor
timestamp: October 07, 2015, 08:50:07 pm
content: It is a 7" diameter circle, thanks.

author: langwadt
author_rank: Super Contributor
timestamp: October 07, 2015, 09:08:28 pm
content: Quote from: alank2 on October 07, 2015, 07:51:11 pmbuy a frying pan?

author: nukie
author_rank: Frequent Contributor
timestamp: October 09, 2015, 01:22:03 am
content: I built a heat plate out of 15cm X 15cm x 16mm thick aluminium deep bore four holes for 4x Hakko 24v heaters ~200w. The whole rig is suspended on silicon feet. The sides are painted high temperature bright yellow paint for visibility. On top of the heatplate I layered an eBay thermal conductive silicon pad, it is soft so it works for uneven boards. This works extremely well for me as it is low voltage and cheap. The most important bit is the thermal transfer. I hate hot air preheat system, I hate it blow hot air on me face especially during summer. The heat plate with the silicon pad does it without air so I'm very happy with it.It is dangerous due to the exposed large surface so does the soldering tip, so does any heat source. As long as there is a board on it I am quite safe.

author: alank2
author_rank: Super Contributor
timestamp: October 09, 2015, 03:23:27 pm
content: Interesting, so you are using a thermal pad. I'll have to try that and see how it does.

author: Mephitus
author_rank: Regular Contributor
timestamp: October 09, 2015, 06:29:13 pm
content: The first thing that came to mind was getting a cast iron plate and then having it enameled in glass to electrically isolate it. I love using enameled cast-iron all the time to cook (Hehe, I'm kinda a dork), which has a completely different set of application needs. Now that I think about it, would that even work?The thermal pad does seem like a good idea though.If you want a cheap supply of metal, check out local machinist shops or places that sell steel building supply. I do some amateur blacksmithing and have run across a few places that have gifted me some fantastic leftover materials just for asking nicely and talking to a manager explaining what I was using it for. Including a 200lb steel block that I used as an anvil for several years. Many will sell their off-cuts for a large discount since selling it to metal recyclers isn't nearly as profitable.