Pin BGA Interconnects
My post "Speaking of Art in the Process " used a photo of a point of load power module as an example. The specifics aren't really relevant to this post though, but a commenter by the name of "Me" asked what type of pins those are connecting the module to the main PCB.
"Do you know where to get those pins to attach two boards like that?
I mean do they sell just the pin for example on digikey and give it a name, or is it just wire.
Can't see if they are pins with a lip to lift board to a set height."
  This part came with the pins already on so I don't have a specific part number for the interconnect pins. I have some underside photos here that give a better view. They are basically solder-type terminal pins with a solder washer and BGA ball on one side (to attach to the main PCB) and either a press-fit or solder type side to affix to the module PCB.
I wasn't able to find this exact part on DigiKey or Mouser. Vector sells the solder washers and lots of interconnect pins of this sort, so they may be able to steer you to them with a phone call. This board uses the BGA style, but we've seen other POL modules of a similar type with thru-hole solder pins too. DigiKey has lots like that. Here's one example  of some thru-hole terminal pins from Mil-Max. You could use the solder-washers (like a T124 from Vector) to put some space between the module and the PCB.