Why the Raspberry Pi Won't Ship In Kit Form

An anonymous reader writes "A post at the Raspberry Pi blog shows an image containing the device's SoC and memory chip to help explain why the tiny PC won't ship in kit form. Clearly, the chips are so small, and the solder blobs required so tiny, that most people would mess up doing it by hand. Add to that the fact one chip has to sit on top of the other, and if you're a millimeter out, your chips are fried." The post also addresses the use of closed source libraries for graphics acceleration.

Comments

BGA packages are intimidating

[vlm]

BGA packages are intimidating, even to a guy who's been hand soldering other SMD packages since around/before 1990 (that being me)

Plain SMD is easy to do by hand, even the 0402 stuff.

The thing with BGA is its an alignment problem. Some entrepreneur will likely invent a magic clamp that holds the chip in perfect registration to the PCB, at which point it'll be dirt simple to solder BGAs.

I donno where the "if you're a millimeter out, your chips are fried" stuff comes from because thats /.ed. I've done analog microwave RF work where that is actually true. That is not possible on a logic level board. "oh noes, /ce has been grounded, whatever shall we do?" Well just fix the solder bridge and stop whining. Its not like you just shorted out a 20 amp 24 volt power supply thru the bias/bypass network of a microwave FET amplifier, nothings going to blow up on a digital ckt.

Re:BGA packages are intimidating

[allanw]

I don't understand why people even want a kit at all. The assembled version is already ridiculously cheap due to high volume. There's tons of surface mount parts that would be annoying to even package for people. Why ruin a perfectly good small form factor to make it a little easier for a few people who want to solder it themselves? Also, it would take you hours of your own time assembling it. Why don't people design their own hardware instead?

The much bigger problem is the lack of documentation on accessing the GPU (which is a more modern design and pretty powerful compared to the older ARM CPU core they're using)

Another issue is that it is very hard to debug an assembled board. If one of the pads on the BGA doesn't make contact it's nearly impossible to diagnose. A power to ground short would be very difficult to locate. They can't use their automated test jig to sort out defective parts or errors in assembly, etc. And then the manufacturer will be prompting tons of support requests by people. It really isn't worth the effort.

Re:Assumptions

[viperidaenz]

It would probably cost more to package the components for a kit than to assemble the thing anyway, so your kit would not only cost more, it would probably never work anyway.

Your reflow oven would need the correct temperature profile, you'd need a solder paste stencil, you'd also need fresh solder paste of the correct type - because it has an expiry date and should also be kept refrigerated.

Re:Worthless as a media streaming device

[Hatta]

HTPCs mess with the signal in all kinds of ways (YUV->RGB conversion is forced, even if you select YUV, it converts to RGB then converts back)

RGB to YUV is lossless in both directions.

Re:Assumptions

[RaySnake]

Well unfortunately the Broadcom SoC used in this is only available to official Broadcom partners. So no, the typical person who wants to do this CAN'T acquire the parts.

Re:Assumptions

[viperidaenz]

Have you ever reflowed a BGA package that sits on top of another BGA package, with 0.3mm pitch? It wasn't stuck down a tiny vibration moving it in to your toaster oven could mis-align it.

Re:Worthless as a media streaming device

[JDG1980]

RGB to YUV is lossless in both directions.

Only if you're working in infinite-precision floating point. In the real world, this is a lossy conversion.