We place them here in the shop and send them through our reflow oven. The direct fets were easier than expected to place.s28400 wrote:Very nice! I look forward to seeing the thermal performance on these! Where do you get the smd placement done after you order from oshpark if you don't mind me asking?
so in theory if you used a piece of kapton tape over each one (or one piece under the heatsink), you could lay one long heatsink over it on each side... then clamp them to the board somehow (maybe a new screwhole or something similar)chaka wrote:Yeah, you need to use a thermal adhesive to attach a heat sinks and keep them electrically insulated from the package. This is still very much in the alpha phase and I may make a few more changes before moving into manufacturing these.
the case sounds cool, but will it make it more difficult to mount to a skateboard?chaka wrote:Kapton might not be the best material. I use it to insulate plastic jst headers when reworking circuit boards. Better to use something like this: https://www.amazon.com/dp/B019MV1TAC/re ... B019MU7NTO
All that is really needed to assemble these is a smd station with a hot air attachment.
We are machining a double sided aluminum case instead of using commonly available heat sinks. You could use the two mounting holes near the phase wires to mechanically fasten some heat sink strips but I am thinking more thermal mass will perform better.
We may make a few more changes to the pcb layout and BOM so I would hold off from building from these files if you want something more polished and final. As stated earlier, we are doubling the amount of fets on the vesc also. If it tests well it may be a great addition for ebikes. Might handle as much as 100 amps constant or more? Time will tell.
I'm using VESC v4.12 on my e-bike. I built a heatsink case and I would like to use Direct FETs with original v4.12 PCB.chaka wrote: ↑Dec 08 2016 4:19pmFor us space is always an issue since we integrate everything into a cavity only 20mm deep and our electronics need to fit into a cavity around 50mm wide so v4.12 is a good fit. Once v6 goes public we will likely rework the pcb files and make a more compact version to suit our needs but it will be more costly so we will still manufacture version 4.12 to keep a lower cost alternative.
We could add all the fets to one side but we have the space for 6 more fets on the original footprint so why not jump up to 12 fets! The encased VESC will only be about 13mm thick so it will be very easy to mount inside an enclosure.