Hi DS! > Just to understand a bit better the costs of fabrication of V2: > does the PCB fabrication include the pick and place of the various > components, or is it just the raw PCB?
The PCB fabrication cost which is expected to be somewhere in the $2600 to $3000 USD range is just the bare PCB panels. We need to use the same PCB fab (pcbcart.com) that was used for FCDEV3B V1 (the precise stackup and choice of specific dielectric materials matters a lot, we went through a lot of work to settle on a good stackup in the previous round that produced perfect RF tract performance on our V1 boards, and I am NOT willing to disrupt all that delicate balance just because someone else who is not in my shoes thinks another fab would be cheaper), and I am also keeping the same panelization structure: 4 boards per panel. If I am going to be paying for it on my own (in however many more months it will take before I can afford it), I will be ordering 5 panels this time, enough to make 20 boards, for me to subsequently sell or give away in the subsidy program as I see fit. > If so, what is the added cost > of the components plus soldering them on each board? The cost of components is not a factor because I have already bought all of the necessary parts (enough for 20 boards), they have already been paid for two months ago, and the physical parts are right here in my hands at FreeCalypso HQ. The final required step will be assembly; it is the step in which all of the components are populated and soldered onto the PCBs in a highly automated manner. It has to be done in a highly automated manner, using a laser-cut solder stencil and a pick-and-place machine because the components are far too small and fine-pitched to be placed by hand. Anyone who claims to be able to solder 0.5 mm pitch micro-BGAs by hand is deluding themselves. I have an established working relationship with Technotronix, an assembly shop here in Southern California, and I will NOT entrust this job to anyone else. The assembly at Technotronix is done on the granularity of panels, not individual boards: a panel that will eventually yield 4 boards is subjected to solder paste depositing (the laser-cut solder stencil covers a 4-up panel, not a single board), populated with components via the pick-and-place machine, and passed through the reflow oven before being split into individual boards. They do both visual and X-ray inspection to make sure that their assembly is correct. Because the pick-and-place machine has to be programmed specifically for our boards and the production line has to be tied up for the duration of our assembly run, doing larger quantities at a time is always appreciated. Doing just one panel at a time raises the cost, thus I strive to do at least two panels at a time (yielding 8 boards) whenever possible. I plan on ordering 5 panels from the PCB fab and then doing two assembly runs at Technotronix: first a run of two panels, then the remaining 3. The intent is to reduce the risk of losing all of the PCBs and all of the parts if someone makes a mistake somewhere: the machines are all automated, but someone has to program them manually, specifically for our board production. Cost-wise, after the initial $2600 to $3000 USD for the PCB fab run, we will need about $1100 for the first Technotronix assembly run ($300 for the stencil + $800 for the 8 boards) and about $1200 for the second assembly run (12 boards, no stencil cost). The laser-cut stencil is a one-time cost, but it will have to be repeated for FCDEV3B V2: we won't be able to reuse the one from V1 because the V2 change adds one fine-pitch SMT component (the 74AXP1T34 voltage level translating buffer), and the SMT pads for this component need to be added to the stencil. However, my main concern is getting the money for the PCB fab run ($2600 to $3000), not the subsequent assembly runs. Once the PCB fab order is placed, it will be another month and a half before we'll have the PCBs to take to Technotronix, and the amount needed for the first run at Technotronix ($1100) is small enough that I hope to be able to cover it on my own during that month and a half of waiting for the PCB fab to deliver. If anyone here would like to see FreeCalypso progress unblock and see FCDEV3B V2 become a reality, paving the way for further developments to follow, and is interested strongly enough to put forth some money, I make the following offer: if you donate $3000 right now and then another $1100 a month or two later (after the PCB fab successfully delivers the PCB panels), you can get two boards from my first assembly batch. Yes, I know full well that this deal is not fair at all in static (time-independent) terms: you would be paying a total of $4100 and getting only two boards for all that money, two boards which would regularly cost only $1000. However, the alternative is to wait an indefinitely long time for me to cover the upfront costs on my own. If no one donates and I have to cover the costs on my own, I *will* do it on my own, and once I have the first batch of boards produced, they will become available for retail sale for $500 each - however, the timeframe is completely indefinite in that case, and it could be many, many months from now. M~ _______________________________________________ Community mailing list [email protected] https://www.freecalypso.org/mailman/listinfo/community
