How Can Trace Mobile Pcb?

If I want to make a scalable electronic sensor device what is the slickest or most elegant way I can fashion an individual sensor PCB that would dock in concert with a scalable number of others to a data acquisition pcb?

• The sensor chip comes in a QFN package and is configured with some digital io inputs and sends data via spi bus.  I really want to get the "unit" sensor array as small as possible, probably 2 QFN chips mounted on either side of a 4 or 8 layer pcb w/ things wired as tight as possible.  I am thinking of starting with these 2 chip sensor units for initial designs ($100 per board in estimated parts and assembly), but could see wanting to scale it up flexibly, docking a handful to a dozen of these to a data acquisition pcb.  Anything especially neat out there I should consider for docking these small pcbs?  I want something that is stable and strong, locking in place, and also small. Is it better to just use wires for an interconnect, mechanically fastening the individual pcbs to an enclosure?  Or are there some other neat interconnects I should highly consider? My problem is in some applications these sensors may be used in the rugged field, whereas in other cases they may be in a stable indoor location.  Thus I need to think about every detail and how things will integrate best in all conceivable applications.

• Answer:

  Make it touch less. Depending on your bandwidth and power requirements it could be possible to make it completely wireless. In my opinion that would be slick. In the absence of that, choose a common and proven connector and protocol. There are many to choose from. Nothing is more frustrating than having to buy a proprietary cable. Personally I'd just put an Ethernet jack on it. Cheap, reliable, relatively high speed, can get cables everywhere. If you need a physical connection from PCB to PCB a flex connector works well for permanent connections. Or you could use a slot (like memory and PCI cards do)