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Iâm dropping up to 40AAC thru a board. Selectable 50Hz / 60Hz. For my protoboard Iâm using 2oz copper on all 4 inner and outer layers, large planes not traces except near the fusing. Iâm not a proponent of fires 
. Standard FR4 material. All components are SMD. RoHS assembly. The components get hot, within worst-case specs, and the board is cool but for heat transfer from the hot components.
Do you recommend different approaches to this scheme? Different board material? 3oz copper on all layers? Different oz copper for different layers - say 2oz internal, 3 oz external? Or 3oz internal and 2oz external for easier assembly? What would that do to PCB cost? Manufacturability? Assembly costs - other than the Technicians will hate me. Itâs small volume. Best way to attach SMD parts to the PCBA to ensure they donât âmeltâ off?
Thanks.
Have you tried our current calculator tool? Kindly visit the link mentioned below and enter your values to find out the necessary conductor width for 40A. What about the number of vias used on the planes? What is the size of via used? You can also try our via current calculator tool. Apart from current, thermal management is also necessary for proper board operation, have you done the power dissipation calculations of various ICs in your board to find out if any additional heat sink is required?
https://www.protoexpress.com/tools/trace-width-and-current-capacity-calculator/
https://www.protoexpress.com/tools/via-current-capacity-temperature-rise-calculator/
Stick with 2oz copper on all layers for your initial protoboard but focus heavily on thermal vias directly under the hot components and also consider heatsinks for the hottest components.
Also need to consider conductor width & via count as per copper thickness & current on the board. You can try our tool from our website.
Iâve done many boards with relatively low current, usually less than 100 Amps on a core voltage. How do you decide how much copper to apply to distribute a core voltage to one of those 1000 Amp GPUs. I know that thermal enters into it but what are the limitations for max. thickness of the planes, how many planes and how much voltage drop you are able to live with on these low (<1Volt) core voltages in going from the supply to IC.
Interesting read: https://www.edn.com/pcb-design-a-close-look-at-facts-and-myths-about-thermal-vias/
thoughts on this?
From our perspective as a fab shop, we definitely agree with a lot of whatâs discussed here especially the point that the copper plane below the thermal vias makes a huge difference. In fact when weâre working with customers on thermal management, one of the 1st things we look at is where those vias are going. If theyâre just âhanging outâ without a good thermal mass to sink into, youâre not getting much benefit no matter how many vias you throw at it.
We also see the reality that while copper-filled vias are ideal for heat transfer (and we do offer them for blind vias), theyâre also a more expensive and time-consuming process than standard open vias or even via-in-pad with a cap. So in real-world designs, itâs a balance, not just thermal performance, but cost, manufacturability, and yield all come into play.
One thing weâd add is make sure your fab shop knows what youâre trying to achieve with your thermal vias. Stack-up planning, via fill type, plane connectivity and whatnot are conversations worth having early to make sure the board build actually supports your thermal goals.
Our design engineers say 100 Amp on a PCB is very special so they need more info from you. Greg will contact you.
Firstly, 1000 Amps will be a challenge to route. Power will have to be distributed across several power planes and routed. Also, equal number of ground plane will be needed along with the power planes to have a safe return path.
We do not have information on the size of the board and high-power components used, the application area, etc. We have done some rough calculations for plane design, assuming good thermal cooling is available. Assuming a 10% voltage drop is allowed, and the distance between the power input and power output of the plane as 10 inches, and the width of the plane is 4.1 inches. A 2-oz plane will support 130-140 Amps of current, and a 3-oz plane will support 200 Amps of current. 1000 Amps will have to be distributed along multiple planes and each plane also needs to have a ground plane as well.