I. Inherent Advantages Adapted to AI Liquid Cooling
Wave springs are manufactured by forming flat steel strips into wave profiles. Compared with conventional cylindrical coil springs, they feature three irreplaceable adaptive merits:
1.With identical load-bearing capacity, the axial installation height is reduced by approximately 50%, fitting the narrow installation space of high-density 1U/2U servers.
2.Multi-point annular force bearing delivers uniform pressure distribution and avoids localized stress concentration.
3.The wave structure comes with inherent damping and excellent fatigue resistance against high-frequency vibration, suitable for server rooms with 24/7 continuous vibration generated by fans and water pumps.
Applicable Working Conditions: Positions with frequent thermal cycling, limited assembly space, persistent vibration and stable pressure requirements. Conventional coil springs can serve as alternatives for low-power liquid cooling equipment with ample installation space.
II. Five Application Scenarios & Practical Functions
1. GPU/CPU Cold Plate Assembly: Stabilize Thermal Conduction & Compensate Thermal Deformation
Installation Position: Cold plate locking structure, located between screw gland and cold plate.
▫️ Uniformly compress TIM (Thermal Interface Material) to achieve full contact between cold plate and chips. Pressure is stable and controllable: insufficient pressure leads to gaps, elevated thermal resistance and chip frequency reduction; excessive pressure damages PCBs and chip packaging.
▫️ Temperature difference between server full load and standby status reaches 60~80℃. Thermal expansion and contraction of metal components causes axial expansion/contraction ranging from 0.02 mm to 0.1 mm. Wave springs dynamically compensate clearances via elastic travel, maintain consistent compression force throughout operation, and eliminate two heat dissipation faults: debonding under high temperature and over-compression under low temperature.
▫️ Accommodate axial dimensional limits of ultra-thin chassis.
Supplementary Note: Low-power liquid cooling systems commonly adopt rigid fastening with pure bolts. Wave springs are widely used for elastic preloading only on high-density, high-heat computing cards such as H100 and GB300.
2. UQD Blind-Mate Liquid Cooling Quick Disconnects: Leakage Prevention for Hot Swap + Long-Term Stable Sealing
AI cabinets realize hot-swap server maintenance relying on blind-mate connectors, which are the fluid components consuming the largest volume of wave springs.
▫️ Spool on-off control: When connectors separate, wave springs push spools to block flow channels, with residual liquid controlled at ≤0.1 mL per industry standard. When mated, connectors compress springs to retract spools and open coolant flow. Unstable spring force directly causes dripping leakage.
▫️ Backpressure compensation for sealing rings: Continuous backpressure is applied to FKM and EPDM sealing rings inside connectors. Against pipeline water pressure fluctuation and server room vibration, sealing surfaces stay tightly fitted. When sealing rings wear thin or swell after long-term coolant immersion, springs automatically extend travel to extend sealing service life.
▫️ Offset minor assembly tolerances to facilitate blind alignment; meanwhile lock fasteners and threads to prevent loosening induced by long-term vibration.
3. Liquid Cooling Valve Assemblies (CDU distribution valves, check valves, pressure relief valves, flow control valves): Controlled Fluid & Pressure Stabilization
▫️ Check valves: Springs drive spool reset to guarantee one-way coolant circulation, prevent liquid backflow during shutdown and avoid gas accumulation & flow blockage inside cold plates.
▫️ Pressure relief valves: Relief pressure threshold is calibrated by spring force. Spools lift for pressure release once pipeline water pressure exceeds the limit; spools reset for sealing after pressure drops, stabilizing pipeline hydraulic pressure and protecting microchannel cold plates from rupture caused by high pressure.
▫️ Multi-path flow regulating valves: Compress dynamic sealing rings to offset seal wear, ensuring long-term even coolant flow distribution among multiple GPUs without flow imbalance as service time accumulates.
4. Pipeline Flanges, End Caps & Water Pump Seals: Anti-loosening + Pressure Compensation for Wear
▫️ Wave spring washers are matched with bolts for cold plate end caps and pipeline flanges to mitigate thread loosening caused by vibration and prevent water seepage on flange surfaces.
▫️ Dynamic seals of water pumps and static pipeline seals maintain persistent compression via wave springs. Coolant immersion ages and thins rubber seals; springs supplement pressure to avoid seal failure and liquid leakage.
▫️ Corrosion-resistant spring materials are mandatory for components contacting coolant. Rust debris from carbon steel easily clogs micron-scale microchannels of cold plates.
5. Whole-Machine Vibration Damping & Assembly Tolerance Absorption
▫️ Absorb axial vibration generated by water pumps and fans, lower fatigue cracking risks of cold plates, pipelines and connectors, and reduce pipeline resonance noise.
▫️ Compensate assembly clearances resulting from sheet metal processing and machining, eliminate metal collision noise during equipment operation and improve long-term operational stability of the whole unit.
III. Material Selection Table Classified by Working Conditions
Materials are divided into dry-type and wet-type based on coolant immersion status:
|
Working Condition |
Recommended Material |
Stable Temperature Resistance Range |
Compatible Coolant |
| Cold plate compression (dry, no liquid contact) |
17-7PH, 304 stainless steel |
-40℃ ~ 180℃ |
No medium; withstands only temperature cycling and vibration |
| Immersed spools of connectors & general valve bodies |
316L stainless steel, Inconel X-750 |
-40℃ ~ 200℃ |
Deionized water, ethylene glycol aqueous solution |
| Severe corrosion immersion (fluorinated liquid, etc.) |
Hastelloy C-276 |
-40℃ ~ 200℃ |
Fluorinated liquid, various anti-corrosion special coolants |
Additional Explanation: 316L stainless steel suffices for cost control on conventional ethylene glycol loops. Inconel is selected to extend fatigue life under high-frequency reciprocation (over one million cycles) and continuous high-temperature thermal cycling.
IV. Objective Comparison Between Wave Springs & Conventional Cylindrical Coil Springs
|
Comparison Item |
Wave Spring |
Conventional Cylindrical Coil Spring |
Material Selection Logic for AI Liquid Cooling |
| Axial Space Occupancy |
50% lower height under equivalent load |
Large height occupation |
Wave springs are prioritized for compact 1U/2U chassis; coil springs are acceptable for equipment above 2U with sufficient space |
| Force Bearing Status |
Uniform multi-point compression |
Line contact prone to stress concentration |
Wave springs are preferred for chip cold plates and sealing surfaces to avoid damage from localized high pressure |
| Vibration Fatigue Resistance |
Damped structure with slow force attenuation under vibration |
No damping, prone to relaxation under long-term vibration |
Wave springs are selected for server rooms with chronic high vibration |
| Temperature Stability |
Minor force fluctuation within small travel |
Obvious force variation after expansion & contraction |
Wave springs fit equipment with large temperature fluctuation |
| Cost |
Higher cost for alloy grades; stainless steel grades share similar cost |
Lower cost for mass production |
Coil springs for cost-sensitive projects with ample space; wave springs for reliability-first scenarios |
V. Common Misconception Clarification
Force Tolerance: No unified industry tolerance of ±3%. Custom connectors from NVIDIA and high-end cold plates adopt ±3% tolerance; mass-produced equipment mostly features tolerance ranging from ±5% to ±8%.
Service Life: Stainless steel delivers cyclic service life of 500,000~1,000,000 cycles; Inconel high-temperature alloy reaches 1,000,000~3,000,000 cycles. No mandatory industry threshold of 1,000,000 cycles applies to all products.
Functional Boundary: Wave springs only stabilize pressure and compensate deformation instead of conducting heat. They cannot raise the upper heat dissipation limit, which is determined by cold plate channel design and coolant solutions.
Application Scope: Wave springs serve as preferred rather than mandatory components. Conventional springs are fully applicable to low-power equipment with adequate installation space.
VI. Final Conclusion
Wave springs are non-core heat dissipation components yet critical elastic parts ensuring reliability for AI liquid cooling systems. Their core value falls into three categories:
1.Pressure Stabilization & Thermal Control: Secure consistent contact pressure of cold plates and sustain heat dissipation performance via deformation compensation.
2.Pipeline Leakage Prevention: Support long-term reliable sealing of blind-mate connectors, valves and all sealing components to avoid damage to computing hardware caused by liquid leakage.
3.Harsh Environment Adaptability: Low-profile size fits compact servers; vibration resistance and thermal cycling tolerance meet the 24/7 operation requirements of data centers.
All specifications and materials must be customized according to installation space, coolant type, temperature and vibration intensity. No universal one-size-fits-all specification exists.
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