[SI-LIST] Re: BGA sockets or a source of compression type material

Heidi,
You're right elastomer like Pariposer or the low cost PCR from RD Circuits
are an excellent choice for hi frequency hand test.  There are probably a
dozen suppliers that have 40GHz+ elastomer sheets, but only the ShinEtsu is
http://www.shinpoly.com/products/interconnectors/ doesn't have to be made
custom to the package and therefore should be lowest cost.  You're right, it
is a problem if you have solder plated pads or solder resist or any
contamination.  A low cost socket with the ShinEtsu could be had from
Ironwood Electronics www.ironwoodelectronics.com and a good low cost socket
with 4GHz pogo pins (~$500)(Low cost being relative) can be had from
www.contechsolutions.com 
Clear skies.
Nick

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Barnes, Heidi
Sent: Monday, February 16, 2009 6:11 PM
To: David Greig
Cc: SI-LIST
Subject: [SI-LIST] Re: BGA sockets or a source of compression type material

Hi Greig,
My favorite has always been Paricon Ball Wire vertical interconnect
PariPoser material for minimal performance difference from that of a
soldered down part at high frequencies.  www.paricon-tech.com I am usualy
dealing with a variety of parts and minimal lead time for custom sockets so
having the ability to just lay a small square of this material down on a PCB
footprint and then with some creative alignment holes or fixtureing I can
gently press the part down into place.  The material is somewhat see through
for the smaller pitches so there is some visibility for alignment to PCB
features.  The biggest issue is that everything must be kept planar and
clean... Which may mean removing soldermask from the PCB footprint and
getting out the fine emery paper to "planarize" the BGA balls. Each little
column of silver plated balls can handle 1 amp of current so I have never
run into the problem of melting the interconnects.  If you are below 1GHz or
~2Gbps in performance then you ca
 n probably find a lower cost pogo pin socket solution, but if high speed
performance is important for showing off your application the PariPoser
material is great for bench top testing and R&D work. 

Regards,
Heidi Barnes



-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of David Greig
Sent: Monday, February 16, 2009 12:32 PM
To: SI-LIST
Subject: [SI-LIST] BGA sockets or a source of compression type material

Dear List
 
I am intending to make physical timing/SI measurements for some DDR3 FPGA
memory controller IP that I have been developing.
This will involve testing with memory devices from several vendors, and
differing speed grades.
I do not have regular low cost access to BGA rework kit and was wanting to
keep the costs down (it's off my own back and funded out of my pocket). 
 
Are there any low cost sockets specifically for DDR bga's, or for that
matter sources of 0.8mm pitch compressible matrix material? Ideally thru
catalogue or online distribution. fclk <= 533MHz.
 
Best Regards
 
David Greig
 

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