[LFS][WTB] 0.4mm-pitch, 49-ball BGA adapter

[blueskull]

Hi all. Is there anyone happens to have a 0.4mm 49 ball BGA socket for Lattice iCE40-CM49 package? Looking for this part number: ICESABCM49-01.
A brand new one from DK is $1300+, and from a smaller distributor it is still $1100+. I'm looking for an alternate solution.
Quality doesn't matter. I need to program a few chips before soldering, I don't need a socket that can be inserted for 10k times while maintaining electrical performance.
So far I can think of is to design a flex PCB, and place it on top of a rubber mat, then press down the chip to the flex with a flat tip tweezers or rubber stick.
I would like to know if anyone has tried this before to program CSP chips without spending $4-digit.

[Asmyldof]

I had a similar need a year ago (MachXO3 in that case). The company, located in the US and China (not 100% sure which one was the origin), stopped comunicating after I showed interest in the quoted figure for quick turn manufacture. In such away I wouldn't suggest them.

If you find a supplier I'm still happy to hear it, though the project parameters have changed (read: budget has shrunk).

The key if you need a socket for programming is to clarify you don't need any speed or power performance from the socket. Standard types are made for appreciable per-pin current and often 100's of MHz to GHz performance, since BGAs of fine pitch are very often found in such domains.

What I ended up doing is buy cheap fine-pitch pogo pins (3 prong, 0.18mm dia) and have 10 boards made with my proto fab that fit them at the premium cost of 3mil/3mil and then solder the pins into 3 boards stacked in a frame, to keep them straight and aligned and then pick the best of the three stacks and recycle the rest. I still prefer having an actual socket, but my time for re-negotiating is too valuable at the moment.

[MadTux]

What about buying a larger, generic 0.4mm pitch BGA socket and inserting the chip together with a spacer (e.g. made from 0.5mm blank PCB material)?

0.4mm BGA sockets aren't exactly cheap, but if you don't need a specific one, cheaper alternatives can be found on ebay, like this one:
http://www.ebay.com/itm/BGA-84X0-4-11-6X8-IC-Test-socket-Program-Burn-socket-Pitch-0-4-mm-IC-Test-socket-/302164037675?hash=item465a61502b:g:DlIAAOSw4GVYThFd

(looks to me as if it's a 0.4mm pitch one from the pictures and drawings, but the description and the pictures don't match)