Interconnect Design Optimization & Predictive Reliability Models for Immersion Cooled Interconnects

Author: Nunga (Technology Manager, Molex); co-authors: Sai Surya, Vishwas Patil, Harish Savant, Govind Tantri Collection: 2024 OCP Global Summit - Cooling Environments & Immersion

Summary

Molex presents a three-year research program (2022–2024) on interconnect design optimization and predictive reliability modeling for immersion cooled environments, focusing on two primary connector candidates: the OCP IT Gear input connector (ORv3 specification) and the Molex Extreme 1060 board-to-board connector. The research trajectory progressed from initial material compatibility mapping (2022, covering both single-phase and two-phase/2PIC fluids, including hydrocarbons and fluorocarbons), to comprehensive electrical/mechanical/environmental reliability testing showing up to 192% current carrying capacity increase in immersion (2023), to design optimization and predictive reliability modeling presented here (2024).

The core engineering insight is that immersion cooling's lower operating temperatures enable two complementary strategies: (1) uprate — use the same connector at higher current, or (2) downsize — use a smaller connector at the same current, recovering material and cost savings. The downsizing results are quantitatively significant: 28% reduction in plating weight (Gold, Nickel, Tin) and 35% reduction in copper content in terminals with negligible change in current carrying capacity; cable resizing delivers a 37% reduction in copper weight per cable at a 7.2% current carrying capacity penalty.

The predictive reliability framework uses three methodologies: accelerated life testing (ALT), run-to-failure (RTF), and Weibull analysis for MTTF (Mean Time to Failure) prediction, combined with the Arrhenius model to convert temperature reduction into reliability improvement. Quantitative result: connectors operating in liquid at 50°C field temperature (vs. 65°C in air) show MTTF of 14.8 years vs. 10 years in air — a 48% improvement in predicted lifetime — based on gold-plated copper activation energy approximation. This correlates to EIA-364-1000 standard correlation: 105°C for 240 hours = 65°C field life for 10 years.