Optimizing Signal Integrity in Immersion-Cooled IT Platforms.pdf

1、Optimising Signal Integrity in immersion cooled IT platformsDr Andy E Young,CTO,AsperitasOptimising Signal Integrity in immersion cooled IT platformsPOWER AND COOLINGCOOLING ENVAs data rates increase the impact of electromagnetic properties of fluids vs.air have an impact on signal integrity.Here we

2、 will learn about what the impact is,and what we can do about it.Credit due to col-lead:Kai Wang,Technical Lead,IntelThe vast majority of servers and switches are design for use in an air-cooled environmentElectrical signals travel along transmission lines inducing electromagnetic field in surroundi

3、ng materialsThese materials cause complicationsInsertion loss(attenuation)cause reflections anddelay transmissionReview of challengeThese complications are accounted for in design(wiggles!)Bringing a multi-gigabit system to market is a major undertaking,due to stringent electrical specificationsRepl

4、acing air with dielectric fluids means potentially that good work is un-done(reduces impendence)Remaking the design for immersion is not currently and optionSo we need to knowWhat are the critical fluid properties to control,and what is the acceptable range?What methods are available to quantify the

5、se effects?What mitigation strategies are used?Review of challengeMicrostripStriplineCablesSocketCritical fluid properitesSolid SubstrateDielectric ConstantLoss Tangent,tanFR4(3GHz)40.008PTFE(3GHz)20.00028Al2O390.002Fluid ImmersionDielectric ConstantLoss Tangent,tanAir10GTL Hydrocarbon2.02 0.02Two-p

6、hase1.9 0.02OCP base spec.2.3 98%After 24 months;no changePCIe 5.0/4.0 and UPI 85%;92%;98%After 24 months and 4 monthEthernet 56G PAM4 per LanePassAfter 24 months;no changeSealed OpticalEthernetPassWIPImmersed ServersBenchmark computational approach with simple microstrip model:Measured 0.20 dBSimul