Thin Form Factor Tunable Cold Plates and Locking Tensioner Cooling Assemblies for Next Generation Memory Modules

Designing thermal solutions for memory is becoming challenging than before. DDRs are getting into the multi-gigabit range and is adopting power hungry technologies like equalization and multi-level modulation that produce distinct hotspots because of higher power density. In conventional Dual Inline Memory Module (DIMM) cooling solutions, heat flux generated on the active layers propagates through multiple layers and interfaces before the benefit of forced convection cooling can remove the heat fluxes thereby generating large thermal resistances. Also, the ever-increasing TDP on these DDR5 DIMMs and the tighter 300 mils pitch between DIMMs makes cooling these devices with adequate thermal margin for higher reliability a challenging proposition. In conventional DIMM passive cooling solutions, DIMMs are increasingly challenging to cool with higher power density and the ineffective capacity of passive system air-cooling solutions to cool them adequately demands active cooling solutions for the tight pitch configurations of the DIMMs.An innovative active DIMM cooling solution such as a tunable cold plate for liquid cooling and a springclip locking tensioner for air cooling is proposed. The springclip retention and locking tensioner heat sink holds the DIMMs captive. The springclip is held captive by a locking tensioner heat sink. The locking tensioner heat sink can be slid out and removed. Once the heat sink is cleared free from the springclips, the clips can be used as a lever to pull the DIMMs out of the DIMM socket. The springclip acts as a retention and no separate retention mechanism is needed. Each springclip is compact in nature and promotes serviceability of DIMMs with ease. The springclips can be made from copper or aluminum and are designed such that the lower part of the springclip is a thin cold plate that exchanges heat from the DIMMs since they are in direct contact with the DIMMs. Thus, the springclips also participate in heat transfer and making them metallic will benefit to spread the heat from the bottom DIMMs to the top heatsinks where the springclips act as an intermediary for heat transfer in conjunction to their primary purpose of retention. In the TDP scenario (24W per DIMM), using embedded Peltier devices showed 25% improvement in DRAM junction temperature. And for the future (DDR6) DIMM TDP scenario (40W), embedded Peltier devices shows a remarkable 41% improvement in DRAM junction temperatures. It is further shown that for higher TDP scenarios, direct cooling with cold plate yields higher than desirable temperature on the DRAMs dictating the need for novel thermal solutions such as the innovation proposed here.