I have a customer who wants me to do an extreme shrink of our semi-custom diode laser controller board, which leads to a lot of thermal issues. The obvious approach is an aluminum-core circuit board, but I've never used one. A few questions for the cognoscenti: 1. Can I get a 6- or 8-layer aluminum-core PCB? 2. How much more do they cost? 3. Any other constraints? Thanks Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Aluminum-core PCB cost?
Started by ●April 23, 2018
Reply by ●April 23, 20182018-04-23
On 23/04/2018 18:31, Phil Hobbs wrote:> I have a customer who wants me to do an extreme shrink of our > semi-custom diode laser controller board, which leads to a lot of > thermal issues. The obvious approach is an aluminum-core circuit > board, but I've never used one. > > A few questions for the cognoscenti: > > 1. Can I get a 6- or 8-layer aluminum-core PCB? > > 2. How much more do they cost? > > 3. Any other constraints? > > Thanks > > Phil Hobbs >I'd also be interested to know whether / how to make connections to the aluminium layer - can it be plated onto? I found a few blank boards made of aluminium with an insulating layer and one copper layer on them: http://www.tjk.com.au/pdfs/TClad_Select_Guide.pdf I have etched the copper layer myself and used them for things like heated IR targets for testing IR sensors, where I soldered SMT resistors to the copper layer and put Kapton tape on the other side to make it emissive. I thought about making some stepper driver boards from the same stuff, but I don't think I could reliably solder the thermal pad of the chip to the aluminium layer, and just soldering it to the copper layer would give quite a lot more thermal resistance, as well as the layout being tricky to do well with just one layer and no connections to the aluminium that could otherwise be a ground plane. One PCB house that I spoke to was also reluctant to put metals other than copper through their etcher in case it contaminates their solution. I would be much happier if the blank boards were made of copper rather than aluminium. Of course that would be more expensive, but being easily solderable would be such an advantage that for one-off projects it seems worth it. It seems that they do make them with a copper core, so if I were buying some more then that is what I would try to get.
Reply by ●April 23, 20182018-04-23
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in news:PcCdnVaFf6trBEDHnZ2dnUU7-KHNnZ2d@supernews.com:> I have a customer who wants me to do an extreme shrink of our > semi-custom diode laser controller board, which leads to a lot of > thermal issues.OK. Use a 0.090" PCB and a LOT of COPPER. The obvious approach is an aluminum-core circuit> board,Ummm... no. Do you think Al conducts heat that much better than Cu? Get a custom copper heat pipe and use thermal epoxy to attach the LED PCB to that.> but I've never used one.I've never heard of one.> A few questions for the cognoscenti: >Right... snip.
Reply by ●April 23, 20182018-04-23
On 23/04/2018 09:31, Phil Hobbs wrote:> I have a customer who wants me to do an extreme shrink of our > semi-custom diode laser controller board, which leads to a lot of > thermal issues. The obvious approach is an aluminum-core circuit > board, but I've never used one. > > A few questions for the cognoscenti: > > 1. Can I get a 6- or 8-layer aluminum-core PCB? > > 2. How much more do they cost? > > 3. Any other constraints? > > Thanks > > Phil Hobbs >Be aware.... a faulty aluminium LED board is a nightmare to rework. Deffo not a DIY job... --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
Reply by ●April 23, 20182018-04-23
On Mon, 23 Apr 2018 04:31:46 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>I have a customer who wants me to do an extreme shrink of our >semi-custom diode laser controller board, which leads to a lot of >thermal issues. The obvious approach is an aluminum-core circuit >board, but I've never used one. > >A few questions for the cognoscenti: > >1. Can I get a 6- or 8-layer aluminum-core PCB? > >2. How much more do they cost? > >3. Any other constraints? > >Thanks > >Phil HobbsThere are also extreme copper boards, from 4 oz up to 20 oz. http://www.epectec.com/pcb/extreme-copper.html My current insane project has a 4-layer PCB bolted to a machined aluminum baseplate, with gap-pad and AlN insulators between. That approach might be more economical. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●April 23, 20182018-04-23
mandag den 23. april 2018 kl. 17.19.08 UTC+2 skrev John Larkin:> On Mon, 23 Apr 2018 04:31:46 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > > >I have a customer who wants me to do an extreme shrink of our > >semi-custom diode laser controller board, which leads to a lot of > >thermal issues. The obvious approach is an aluminum-core circuit > >board, but I've never used one. > > > >A few questions for the cognoscenti: > > > >1. Can I get a 6- or 8-layer aluminum-core PCB? > > > >2. How much more do they cost? > > > >3. Any other constraints? > > > >Thanks > > > >Phil Hobbs > > There are also extreme copper boards, from 4 oz up to 20 oz. > > http://www.epectec.com/pcb/extreme-copper.html > > My current insane project has a 4-layer PCB bolted to a machined > aluminum baseplate, with gap-pad and AlN insulators between. That > approach might be more economical. >some time ago I saw this 20oz board on reddit: https://usercontent.irccloud-cdn.com/file/gHochdce/irccloudcapture-1320676838.jpg the guy said it cost $2250
Reply by ●April 23, 20182018-04-23
On Mon, 23 Apr 2018 08:49:42 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>mandag den 23. april 2018 kl. 17.19.08 UTC+2 skrev John Larkin: >> On Mon, 23 Apr 2018 04:31:46 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >> >I have a customer who wants me to do an extreme shrink of our >> >semi-custom diode laser controller board, which leads to a lot of >> >thermal issues. The obvious approach is an aluminum-core circuit >> >board, but I've never used one. >> > >> >A few questions for the cognoscenti: >> > >> >1. Can I get a 6- or 8-layer aluminum-core PCB? >> > >> >2. How much more do they cost? >> > >> >3. Any other constraints? >> > >> >Thanks >> > >> >Phil Hobbs >> >> There are also extreme copper boards, from 4 oz up to 20 oz. >> >> http://www.epectec.com/pcb/extreme-copper.html >> >> My current insane project has a 4-layer PCB bolted to a machined >> aluminum baseplate, with gap-pad and AlN insulators between. That >> approach might be more economical. >> > >some time ago I saw this 20oz board on reddit: >https://usercontent.irccloud-cdn.com/file/gHochdce/irccloudcapture-1320676838.jpg > >the guy said it cost $2250 > > > >Looks silly, 20 oz copper and skinny traces. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●April 23, 20182018-04-23
On Monday, April 23, 2018 at 2:31:59 AM UTC-6, Phil Hobbs wrote:> I have a customer who wants me to do an extreme shrink of our > semi-custom diode laser controller board, which leads to a lot of > thermal issues. The obvious approach is an aluminum-core circuit > board, but I've never used one. > > A few questions for the cognoscenti: > > 1. Can I get a 6- or 8-layer aluminum-core PCB? > > 2. How much more do they cost? > > 3. Any other constraints? > > Thanks > > Phil Hobbs > > -- > Dr Philip C D Hobbs > Principal Consultant > ElectroOptical Innovations LLC / Hobbs ElectroOptics > Optics, Electro-optics, Photonics, Analog Electronics > Briarcliff Manor NY 10510 > > http://electrooptical.net > http://hobbs-eo.com10 units of, say: 50mm x 50mm, 8-layer, 1oz.Cu, 2mm thick aluminum boards are going to be around $400 - $500 (USD) from a Chinese shop. Going to 3oz. Cu is roughly double. Double the price again for US manufacture. Specs tend to be largely the same as for typical FR4 boards (trace/space, holes sizes, etc.). Not cheap, but if you need to spread the heat, it is a good way to go.
Reply by ●April 23, 20182018-04-23
Sorry, what is the benefit of Al over Cu here? Cu has higher thermal conductivity, 3x the density and is the standard material for PCBs. Is the idea that Al will radiate heat away faster? Wouldn't a Cu PCB with Al heatsink be the better choice then?
Reply by ●April 23, 20182018-04-23
Marke <mark.e.emerson@gmail.com> wrote:> Sorry, what is the benefit of Al over Cu here? Cu has higher thermal conductivity, 3x the density and is the standard material for PCBs.The Al is not instead of the Cu, it is instead of (part of) the FR4. Of course it would be even better to use an equivalent thickness of copper, but it would be more expensive.
