The compute module 3 uses a “DDR2 SODIMM” 200pin connector

DDR2 is the 1.8V DRAM version of the connector, DDR is the same but designed for 2.5V DRAM modules. There is a difference in the gap size required on the PCB module for it to be able to be fitted, with the gap needing to be wider for DDR2.

Using a DDR connector

Some users have reported that hacking the compute module to widen its gap will allow it to fit in a DDR socket but can result in it no longer working, indicating there might be PCB traces very close to it – we’ve not confirmed this though. Regardless, with the connector having 0.6mm pad spacing it takes a very accurate hack to ensure that the contacts will be positioned correctly afterwards and avoid them not aligning correctly.

Horizontal mounting the Compute Module

TE Connectivity 1473005-4

Vertical mounting the Compute Module

Most DDR2 SODIMM connectors are right angle, in that the memory module / compute module fits into it so that is sits flat above the PCB. If you want to mount your compute module vertically, so that you increase height and reduce PCB footprint, then whilst there are some DDR connectors easily available in this format, DDR2 options seem to be pretty limited. Some connectors we’ve come across which may be suitable:

JST DM-7D4-H2500 (JST , JST ordering – min qty 224)
TE Connectivity 2040910-2 (looks hard to source in small quantities)
TE Connectivity 2040910-3 (looks hard to source in small quantities)