@sortius it’s recoverable, but a pain in the arse to do, and not really worth it for a first manual assembly of a first prototype where anything above “it doesn’t work at all” is a bonus!
@sortius and it’s 4 unusable, even though there’s bridges between 8 pins, because they are “simple” low-speed GPIO pins and I can still use either of the two bridged pins but not both independently
@jpm time to melt down a butter-stick-sized bit of rosin for some flux, steal the toaster oven from the kitchen and disable any smoke alarms in the garage for an hour
@ThermiteBeGiants mate I’m not trying to solder railway tracks together! But yeah it’s going to need plenty of flux, high-grade SAC305 solder, and a very steady hand
@ThermiteBeGiants as mentioned else-thread, this is even more insane than a normal 0.4 pitch BGA, because the lands have been slightly squished to fan out the middle ring without using vias while also meeting the 0.09mm trace and space.
Yes, those BGA lands have been squashed into ovals from their normal circular shape, so I could route traces between them. Doing that on 0.4mm BGA pitch is pretty insane, and this board is definitely walking straight into the realm of “I expect this to not work”
Hm, maybe I should keep the solder mask as normal 0.2mm circular holes, to keep the PCB manufacturing process a bit happier. It’s not like I care about matching the mask to the land, I just care about being able to solder to the land…
@jpm 0.4mm is pretty close to the smallest increment I'll bother adjusting by to get a 3d print to fit something else. That's the only thing that gives me any sense of scale to what you're attempting and my first thought is "could JLC have supplied the board with U1 pre-installed?"... But I assume what you're doing relies on being able to do that but yourself. Good luck!
@voltagex@timixretroplays sure they can, they only build the bits you specify. You’d need to make sure the solder stencil they create only has apertures for the part(s) you want though.
This board only has 6 parts in total - U1 and 5 passives…
@timixretroplays also for sense of scale, most 3D printer nozzles are 0.4mm diameter. Take a 3D printer nozzle, and the edges of the aperture will overlap the centers of 2 adjacent pads here. The pads themselves are nominally 0.25mm diameter, which is why I had to squish them a bit to fit the 0.09mm minimum trace width and spacing.
@timixretroplays and yes, JLC does offer PCB assembly services, but there’s a minimum board size required for that which blows the cost WAY out for just the board, let alone the assembly. Once I get happy with the prototypes I’ll see what the demand is like for actually doing a manufacturing run and slapping maybe 10 of these boards into a panel which can then be assembled
Add comment