jlcpcb? @Hamspiced uses them.. seems to have descent results?
I think OSHPark is @enginerdās preferred supplier
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They are based in the US. And the quality of the purple fab is top notch!
Not sure if this stackup will fit the application tho:
Why did I get used to crayon eating units for PCB design!? I think thatās 0.22mm.
And apparently the flex service is suspended for the time being:
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I do not recommend oshpark for any antenna designs. My measurements are way off with them
Yes 100%. Pcbway is usually almost double if not more than that of jlcpcb and I had continual quality control issues with pcbway
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If that was with their flex service, we now know why itās suspended for the time beingā¦ Something something dielectric constantā¦
Are donations still open? Iād be willing to put at least some money towards the project to help with costs
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We used jlcpcb exclusively at my last job. Nothing fancy like flex pcb or on-board antennas but we were happy with them
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Iāve been back and forth with them and the costs seem unavoidable because of the vias filled with copper which is necessary for this design. If people keep donating it would be appreciated. I can probably cover most of it but Iāll request a reimbursement to the open collective after
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I ordered the PCB and paid for them. Theyāre 18% complete and Iām continuing to answer their questions about the fabrication. They were very expensive for 16 units.
I finally got through to several sellers on Alibaba and got quotes on the 128GB NAND flash eMMC chip. Unfortunately they want even more money for the flash chips than domestic suppliers. Theyāre currently $155 on Digikey with 74 in stock and the price is rising by the day. Iām currently struggling with a plan to address this since the PCBs were already unexpectedly 3.2x the price. Iāll have to ask Amal for more money for his units, and send another request to the open collective for the most recent donations, but that brings the total money Iāve raised from all sources to 2350USD. The PCBs were 1450USD, and each flash chip is $155 which is the limiting factor (the rest of the components are ~50USD). Iāll throw in some of my money and try for 7 units. Two will go to Amal and one will be sacrificed to the population daemons. That should leave 4 for development.
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Getting some of my other invoices sorted and then Iām gonna order the parts. If anybody wants to get in with a few more donations in the next couple days before I request a reimbursement from the open collective it would be greatly appreciated. Iām handling whatever the difference is and Iāve already put a lot of myself into this. I still need to get some machining or metal printing done to aid with population too. If anybody would be down to machine some aluminium for me feel free to reach out.
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What aluminium stuff do you need? Stencil?
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Nah I need an aluminium block to rest the PCB in during assembly and reflow. The NAND flash and DRAM chips on the bottom are BGA with unleaded solder balls. I usually use low melt bismuth solder for implant PCBs to not thermally stress the components, but you canāt mix that with BGA solder balls because it corrupts the integrity of the solder joints. My plan is to solder the two BGA chips first, then flip the PCB over and rest it in an aluminium block with cutouts for the PCB and those two components. Once resting in there it will be easy to apply the low melt solder to the top side and populate the components with my pick and place, then place the whole aluminium block in my reflow oven. The low temperature of the low melt reflow will leave the BGA parts unaffected. Iāll make a 3D model and share. Maybe somebody can take care of that for me, if not directly then maybe working with a service.
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I have some friends that have access to a machine shop. No promises but Iāll see what I can do
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Hereās some files that would help anyone make the assembly jig we need. I tried to make it as easy to manufacture as possible. Nothing needs to be very precise, even like 1mm tolerances are acceptable. The only kinda important bit is the size of the cutout in the center. The metal sheet must be at least 1mm thick but I donāt think I can support much more than 3.125mm (1/8ā) thick. It could be steel but I would prefer aluminium due to its thermal properties and corrosion resistance.
Bodybytesv1-0_AssemblyJib_TopPlate[Drawing].pdf (95.0 KB)
Bodybytes_AssemblyJig_STEPFiles.zip (782.9 KB)
I also need a solution to cut out the ferrite sheets to the correct shape, so maybe whoever can help with this can also come up with a solution for that.
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Oh yeah I mean I can just upload that to JLCPCB or PCBWay or send cut send. DM me your address. How many do you need? Any niceties youād want on the jig?
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What shape do you need the ferrite sheet in? Can you send a link to the sheet you want to use?
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Something more exact to the dimensions of the bodybytes would be cool but honestly kinda unnecessary. Iād be more worried that it will be off and too small so I left plenty of room. I also want to keep things as simple as possible in all aspects of this project since itās open source and I want anyone to be able to make it
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