Aluminum Core PCB vs Copper Coining - Page 1
Forum section: electronics / projects

author: meshtron
author_rank: Regular Contributor
timestamp: February 11, 2025, 04:00:39 pm
content: I use PCBWay to build my boards and last night as I was working through getting a quote started, I saw the "Embedded Copper" option that I haven't seen before:https://www.pcbway.com/helpcenter/ordering_parameter_instruction/What_is_Embedded_copper_PCB_.htmlMy board is small (80mm X 50mm) with a large heat sink on the opposite side of the primary heat-generating component (a high-side driver IC dissipating 9W maximum). I've been working hard to make good thermal paths from the chip-side to the heatsink-side but this copper embedding/coin sounds like exactly the problem I'm trying to solve - giving the best possible thermal path through the board.So just curious if anyone has used this kind of solution and - besides straight cost - what would be your key decision points to go this route vs aluminum core board?

author: tszaboo
author_rank: Super Contributor
timestamp: February 11, 2025, 04:23:52 pm
content: Aluminium PCB is usually 1 layer. Copper coin is going to cost a lot more, but you also get more layers, maybe controlled impedance and other nice things.

author: langwadt
author_rank: Super Contributor
timestamp: February 11, 2025, 04:58:26 pm
content: Quote from: tszaboo on February 11, 2025, 04:23:52 pmand probably better thermal resistance because there's no isolating layer between the part solder pad and the backsidethese were interesting, but I don't think the company exist anymore,https://d3s5r33r268y59.cloudfront.net/datasheets/7790/2016-10-25-22-31-17/Design_Reference.pdf

author: meshtron
author_rank: Regular Contributor
timestamp: February 12, 2025, 03:51:28 pm
content: Quote from: langwadt on February 11, 2025, 04:58:26 pmYeah that's a nice little part, makes a lot of sense. All my signals are low-speed and I'm ordering a 2-layer aluminum board (part of why it's expensive). 2oz copper both sides too (there are some high-current sections). I will probably just stick with aluminum for this round (at least according to all my math, it should get me the thermal transfer I need) but I will probably explore a bit more with PCBWay to see what's possible/plausible for coining.

author: tszaboo
author_rank: Super Contributor
timestamp: February 12, 2025, 03:58:52 pm
content: Quote from: meshtron on February 12, 2025, 03:51:28 pmYou might want to double check, what they mean by 2 layer board. Often times it's just a metal core, isolating layer and 1 normal layer. Or it's double sided, and then you cannot bolt it down to a heatsink.

author: meshtron
author_rank: Regular Contributor
timestamp: February 12, 2025, 04:17:29 pm
content: Quote from: tszaboo on February 12, 2025, 03:58:52 pmFortunately PCBWay is nicely explicit with this but yeah, I found exactly what you're describing other places. JLCPCB, for example, will only offer 1-layer boards with aluminum substrate. This is from the PCBWay quote page.

author: tszaboo
author_rank: Super Contributor
timestamp: February 12, 2025, 04:21:13 pm
content: Quote from: meshtron on February 12, 2025, 04:17:29 pmLooks interesting. I wonder if they have vias in the "IMS in the middle" option?

author: meshtron
author_rank: Regular Contributor
timestamp: February 12, 2025, 04:29:24 pm
content: Quote from: tszaboo on February 12, 2025, 04:21:13 pmThat I do not know. I have some in-pad vias in this design (again, for thermal transfer) and debating on filling all vias to keep more copper on top and bottom. But I think the potential benefits may not be worth the cost. Gotta finish my layout so I can get this order placed!

author: Langdon
author_rank: Frequent Contributor
timestamp: February 12, 2025, 04:34:22 pm
content: What about soldering a piece of tinned copper sheet metal as a heatsink to the board?

author: Langdon
author_rank: Frequent Contributor
timestamp: February 12, 2025, 04:46:23 pm
content: Just manually solder the Copper as a heatsink after they arrive.What about those thermal pads that are sometimes placed on top of components that get hot?

author: meshtron
author_rank: Regular Contributor
timestamp: February 12, 2025, 04:47:27 pm
content: Quote from: Langdon on February 12, 2025, 04:34:22 pmNot sure I understand. I have a hot (9W) component on one side and a large 40x40mm heat sink on the opposite side, centered on the hot part. So my focus is really getting heat from the junction on the IC through its base, through the board to the heat sink. That's why the coining idea seems interesting - straight-shot copper from the hot part to the heat sink!

author: tszaboo
author_rank: Super Contributor
timestamp: February 12, 2025, 05:42:03 pm
content: Quote from: Langdon on February 12, 2025, 04:46:23 pmWould you also do that if you build a thousand boards?Quote from: meshtron on February 12, 2025, 04:29:24 pmI think finish up and measure it. I don't think via filling would make a large difference.Thermal design is tricky, and I prefer doing my own tests before making any decisions.

author: dkonigs
author_rank: Regular Contributor
timestamp: February 12, 2025, 06:50:15 pm
content: Another option that I'm currently exploring is JLCPCB's direct heatsink copper core PCB:https://jlcpcb.com/blog/JLCPCB-Direct-Heatsink-Copper-Cored-PCBs-Available-Now!I'm currently getting one of these made to test for an application of mine, and eager to compare with an Aluminum PCB of the same circuit. The main issue with it is that its only useful for components with isolated thermal pads, or in cases where you're okay connecting all thermal pads to the same net. They're also 1-layer, like Aluminum PCBs.Fortunately the component I care most about sinking heat away from does have a dedicated thermal pad I can connect. Unfortunately, some of the others either don't, or do but I can't connect them without causing huge problems for clean trace routing.

author: Langdon
author_rank: Frequent Contributor
timestamp: February 13, 2025, 01:53:09 am
content: Quote from: tszaboo on February 12, 2025, 05:42:03 pm1000 boards x 1 minute per board = 1000 minutes ≈ 17 hours.I would not want to spend 17 hours soldering heatsinks.That is not a viable solution.What about stick-on heatsinks?Try to use copper wherever at all possible; it conducts heat very well, much better than aluminum ever could.I bought a cheap "DM556" motor driver off Ebay; it has a bunch of TO-252 transistors (I think they're transistors, whatever).There is a thermal pad between the transistors and the big heatsink.It seems to work fine (the pad was originall misaligned, but I fixed it).EDIT: Originally miscalculated number of hours (I accidentally typed in 100/60instead of 1000/60)

author: meshtron
author_rank: Regular Contributor
timestamp: February 13, 2025, 02:06:00 am
content: An hour is 500 minutes where you come from?

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2025, 02:21:20 am
content: Quote from: tszaboo on February 11, 2025, 04:23:52 pmAny idea what physical process they use to make and place the copper coining?

author: tszaboo
author_rank: Super Contributor
timestamp: February 13, 2025, 10:00:55 am
content: Quote from: bdunham7 on February 13, 2025, 02:21:20 amAs I understand, these are standard parts that get press-fitted into the core. And sometimes it happens before the plating.Quote from: Langdon on February 13, 2025, 01:53:09 amOk, so that's 17 hours for starters. Then you have setup costs, training, fiddling around. Heating up huge, thermally conductive parts. But I've seen the workers much slower than this, you can easily count 20-30 seconds just for a standard through hole soldering connection. That is, if you have to do that the whole day.And for these sort of things, your yield is usually low, and skill requirements is high. To place 4 bolts with a torque controlled driver, it's the other way around.Quote from: dkonigs on February 12, 2025, 06:50:15 pmI had one of these copper PCBs from the Bergquist company. The thing you don't expect, how heavy these PCSs are, it's actually quite impressive.

author: Langdon
author_rank: Frequent Contributor
timestamp: February 13, 2025, 07:03:08 pm
content: Quote from: meshtron on February 13, 2025, 02:06:00 amFixed it now!Sorry.Arithmetic error!

author: meshtron
author_rank: Regular Contributor
timestamp: February 13, 2025, 11:10:50 pm
content: Quote from: Langdon on February 13, 2025, 07:03:08 pmNo apology needed - I was thinking I needed to move there and increase my productivity per day!