Applying Raspberry Pi's PCB Manufacturing technique ?


Wiz

Still Fresh
Joined
Aug 28, 2010
Messages
7
Hello, awesome community ! :)


Long time lurker, enjoying my lovely 256MB CC Pandora since April 2011 with no problem :wub: , and now enjoying my Raspberry Pi as well !


... which made me read a interesting article, here's the link :


http://www.wired.com...ut-to-sell-out/


And here is what got my attention (sorry in advance if it's been discussed already) :

The problem? We couldn’t manufacture it anywhere near our target cost. It turned out that there was a looming problem routing the PCB to accommodate the design.

This wasn’t just a minor technical detail: The solution to the problem meant our budget would be well and truly blown. The core of the design involves wiring up all the peripheral connectors, support chips, and five power supplies – most of which have to fit under the processor. But we had 253 connections to bring out (the BGA escape) in an area much smaller than the size of a dime.


And while there are special high-density interconnect (HDI) techniques for densely layered PCBs, those would just reduce yield and increase processing steps not to mention the costs. We panicked when we realized we might have to increase prices to accommodate the HDI technology.


But failure was not an option – we simply had to find a way.


After much fiddling with all the possible variables, and a few frantic calls to our PCB manufacturers, we had our Eureka moment. What if we could steal the idea of “blind micro vias” from high-density interconnects, but apply it cheaply enough for the Pi design?





Instead of going through all the PCB layers, we made human-hair sized holes (micro vias) that go through only the first couple of layers (blind) – saving just enough space on the other layers for wiring up the other PCB components. At high volumes, these holes could be made quickly and efficiently with a laser. And it only cost a few cents extra. Making these tradeoffs resulted in a relatively simple six-layer board that didn’t compromise power distribution. And it enabled manufacturing at scale.

So, to make things clear, I'm not a PCB tech guy and I honestly don't get how it works exactly. :lol:


But to me, it looks like the RasPi team found a cheaper way to make complex, multi-layered PCBs.


So if I'm not wrong : could this manufacturing technique be of any use to the Pandora team for future projects ?


Here, question asked, and thanks everybody for being part of such a great community, long live the Pandora and the ICP :D
 
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