Water Cooled Heat Sink
A water cooled heat sink — more precisely a liquid cold plate — removes heat from high-power electronics by circulating a coolant through internal channels cut into a metal plate. Because a liquid carries orders of magnitude more heat per unit of flow than air, a cold plate holds thermal resistance roughly an order of magnitude below any finned air-cooled sink.
- Product Introduction
A water cooled heat sink - more precisely a liquid cold plate - removes heat from high-power electronics by circulating a coolant through internal channels cut into a metal plate. Because a liquid carries orders of magnitude more heat per unit of flow than air, a cold plate holds thermal resistance roughly an order of magnitude below any finned air-cooled sink. We manufacture water cooled heat sinks as machined-channel and brazed designs for IGBT, SiC, power modules, servers, EV, and energy-storage systems where convection simply tops out.
- Two build routes - CNC-machined channel plates and vacuum-brazed cores, tuned to pressure, flow, and power
- Very low resistance - case-to-coolant typically 0.03–0.15 °C/W, far below air-cooled limits
- Sealed and safe - 100% pressure- and leak-tested, with flow and pressure-drop curves per batch
- Built for your device - inlet/outlet, mounting, and fluid matched to your module and loop
What a Water Cooled Heat Sink Actually Does
A water cooled heat sink is not a finned radiator - it is a plate with coolant channels. Heat from the device flows into the plate by conduction, then into a moving liquid (water/glycol or a dielectric fluid). The warmed liquid is pumped to a remote radiator, where a fan rejects the heat to ambient. The plate itself stays small; the rejection happens far away, which is exactly why liquid cooling works in sealed or compact enclosures where a finned air sink has no airflow and no room.
The number that matters is case-to-coolant thermal resistance (°C/W). A good liquid cold plate lands at 0.03–0.15 °C/W, whereas even a large forced-air finned sink is typically 0.3–1.0 °C/W and a passive one is 1.0–5.0 °C/W. For a 3 kW module that is the difference between a 30 °C rise and a 200 °C rise - and the difference between a product that ships and one that de-rates in the field.
Engineering rule for buyers: Once your device exceeds roughly 100–150 W/cm², or your enclosure is sealed, or you have no forced-air budget, air cooling stops being viable. That is the moment to move to a water cooled heat sink. Send us the module footprint, total heat load, allowable flow and pressure drop, and the fluid you plan to run, and we return a channel layout and a case-to-coolant resistance estimate before any tooling.
Water Cooled Heat Sink: Three Views
A cold plate looks simple from outside; the work is inside. These three views show the internal channel, the finished part, and the device-on-plate assembly.
Channel cross-section
Machined or brazed internal path. Layout sets pressure drop and heat pickup.
Finished plate
Inlet/outlet fittings, drilled and tapped mount holes to match your module.
On-device
Module bolted to the flat face; loop moves heat off-board to a remote radiator.
Why Buyers Specify Our Water Cooled Heat Sinks
One Accountable Supplier
The plate, the fittings, the leak test, and the documentation come from one source - one PO, one CoC, one incoming-inspection routine instead of splitting a fluid part across shops.
For Procurement Teams
Resistance You Can Trust
We simulate the channel layout and report case-to-coolant resistance, flow, and pressure drop before tooling, so you size the pump and radiator against real, measured numbers.
For Thermal / Design Engineers
Clears the Power-Density Wall
For IGBT/SiC modules above ~100 W/cm², sealed enclosures, or compact inverters, a liquid cold plate is what makes the design feasible - air cooling cannot.
For Power Electronics OEMs
Stock & Private Label
Standard plate footprints kept neutral or branded, with tiered pricing for recurring programs across server, EV, and energy-storage customers.
For Distributors
Technical Specifications
Reference range for our machined-channel and brazed water cooled heat sinks. Exact values are set by your device footprint, flow, and fluid.
| Parameter | Specification |
| Construction | CNC-machined channel plate (tube-less) or vacuum-brazed fin/tube core |
| Plate Material | Aluminum 6063/6061; copper base on request for high flux |
| Coolant | Water/glycol(e.g., 50/50 EG), or dielectric fluid (two-phase) for isolated loops |
| Case-to-Coolant Rθ | 0.03–0.15 °C/W typical (design-dependent) |
| Operating Pressure | Up to 3–5 bar; burst tested to 2× working pressure |
| Flow Rate | 0.5–4 L/min per plate typical; matched to pump |
| Surface Flatness | ≤ 0.05 mm on the mounting face; lapped on request |
| Mounting | Drilled/tapped M3-M6, matched to module footprint |
| Fittings | Barb, compression, or threaded (G/NPT) per spec |
| Certifications | RoHS, REACH, ISO 9001; PPAP on request |
Water Cooled Heat Sink Selection Guide
Pick the construction and fluid from your power density, enclosure, and isolation needs. Air-cooled fins remain the default below the liquid threshold; a cold plate takes over above it.
| Application | Heat Load/Density | Recommended Build |
| Single IGBT/MOSFET module | 0.5-3 kW,＜ 80 W/cm² | Machined-channel aluminum plate, water/glycol |
| SiC / high-flux module | 3–10 kW, 80–200 W/cm² | Brazed copper-in-aluminum or copper plate, dielectric option |
| Server / rack blade | High uniform load | Machined micro-channel plate, water loop |
| EV inverter / on-board charger | Pulsed, vibration | Brazed plate, vibration-rated fittings, glycol |
| Energy-storage PCS | 10–100+ kW | Parallel brazed plates, glycol, remote radiator |
| Isolated / live loop | Any | Dielectric two-phase fluid; no conductive coolant |
| Below ~100 W/cm², open airflow | Low density | Use air-cooled finned sink instead - see related pages |
Technical Differences: Liquid Cold Plate vs Air-Cooled & Heat-Pipe Cooling
| Method | Thermal Resistance | Power Density | Enclosure | Complexity | Notes |
| Passive air finned sink | 1.0–5.0 °C/W | Low | Open/vented | Lowest | Cheapest; fails in sealed or high-density cases |
| Forced-air finned sink | 0.3–1.0 °C/W | Medium | Vented+fan | Low-Med | Good up to ~100 W/cm²; noisy, dusty |
| Heat pipe / vapor chamber | 0.15-0.5°C/W | Medium-High | Sealed ok | Medium | Spreads heat to a remote fin; still rejects by air |
| Liquid cold plate (this page) | 0.03–0.15 °C/W | High–Very high | Sealed ok | High (needs pump/loop) | Highest capability; moves heat fully off-board |
A water cooled heat sink is one of three ways to move large heat loads. Each trades cost, complexity, and capability differently. Here is how a liquid cold plate compares to the air-cooled finned sink and the heat-pipe / vapor-chamber approach.
Rule of thumb: Stay with a finned or heat-pipe air sink until you cross ~100 W/cm², run a sealed enclosure, or run out of space for fins and fan. At that point a liquid cold plate is not "better marketing" - it is the only option that holds junction temperature. We help you decide at RFQ and can supply both air and liquid routes, so the recommendation is not forced by what we happen to build.
Material & Fluid Comparison: Aluminum vs Copper Plate, Water vs Dielectric
The plate material and the coolant are independent choices. Each trades thermal performance, weight, cost, and safety differently - the table contrasts the practical properties a buyer cares about.
| Option | Thermal Conductivity | Weight | Cost | Corrosion/Safety | When to Use |
| Aluminum plate+water/glycol | Good (237 W/m·K) | Light | Low | Needs corrosion inhibitor | Default; most IGBT/PCS/server loops |
| Copper plate + water/glycol | Excellent (401 W/m·K) | Heavy | Med-High | Inbibitor;heavier bracket | High flux / SiC where every °C/W counts |
| Aluminum + dielectric fluid | Good | Light | Medium | Non-conductive, safe on live parts | Isolated loops, two-phase, electrical safety |
| Copper + dielectric fluid | Excellent | Heavy | High | Non-conductive, safe on live parts | Highest flux + isolation required |
| King | 183*203 | 37*37*193 | 108PCS | 252PCS |
The plate material and the coolant are independent choices. Each trades thermal performance, weight, cost, and safety differently - the table contrasts the practical properties a buyer cares about.
Recommendation: For the vast majority of power-electronics loops, an aluminum cold plate with inhibited water/glycol is the right default - strong thermal performance at the lowest weight and cost. Move to a copper base only when flux is extreme (SiC, >150 W/cm²) and the extra weight is acceptable. Choose a dielectric fluid when the loop can contact live parts or you need two-phase cooling; reserve stainless for genuinely corrosive coolants where conductivity is secondary.
Application
IGBT & SiC Power Modules
Traction, welding, and grid converters where junction temperature is the hard limit.
Energy Storage PCS
Parallel brazed plates for 10–100+ kW bi-directional converters with remote radiators.
Servers & Data Center
Liquid-cooled blades and GPUs where air cannot keep up with rack density.
EV Inverters & OBC
Vibration-rated brazed plates for on-board chargers and traction inverters.
Laser & Medical Imaging
Stable, low-noise cooling for high-power laser diodes and imaging detectors.
Industrial & Test Equipment
Sealed cabinets and bench equipment where dust and noise rule out fans.
Manufacturing Process
A water cooled heat sink is built and then validated as a pressure vessel - the chain ends with leak and flow testing, not just a visual check.
Design
Channel layout, R & Pressure-drop sim
Machine/Braze
CNC channels or vacuum-brazed core
Face Finish
Fly-cut / lap mounting face flat
Machine Ports
Drill, tap, fit inlet/outlet
Clean & Seal
Deburr, passive, plug openings
Leak & Flow Test
Pressure hold+flow curve per unit
Quality Inspection (Cold Plate & Leak Testing)
A water cooled heat sink is a pressure boundary, so inspection targets what causes field failures: leaks, blocked channels, and a flat face that will not transfer heat. Every plate is checked against the plan below.
| Inspection Point | Method | Acceptance |
| Incomming material | Mill cert+spectrometer spot check | 6061/6063 or copper per order |
| Leak / pressure | Helium or nitrogen pressure hold | No drop at 2x working pressure |
| Flow & pressure | Bench flow rig | Within ±10% of simulated curve |
| Channel continuity | Flow+optional dye trace | No blockage; full path wetted |
| Mounting-face flatness | Surface plate/CMM | ≤ 0.05 mm; lapped if specified |
| Surface finish/burr | 100% visual, deburr check | No sharp edge, no debris in channels |
| Fitting torque | Torque verification | Meets spec; no crack at ports |
| CoC/traceability | Batch record | Leak report, flow curve, material cert, RoHS/REACH |
For buyers: Ask for the leak-test and flow-curve record with your first order - we issue a Certificate of Conformity (CoC) and can supply PPAP-level documentation (including the thermal simulation report) for automotive or energy-storage programs on request.
Cost Factors
A liquid cold plate costs more than an air-cooled sink because it is a machined, tested pressure part - but it is almost always cheaper than re-rating or de-rating your whole system to stay within air-cooling limits. The levers that move price are below.
| Factor | Effect on Cost | Buyer Tip |
| Construction | Machined-channel | Machined-channel is enough for most single modules |
| Material | Aluminum< copper< stainless | Aluminum default; copper only for extrueme flux |
| Flatness/lap | Lapping adds cost | Spec lap only if the module requires it |
| Channels complexity | Micro-channel>serpentine | Serpentine convers most loads |
| Fittings | Standard barb | Use standard ports; custom adds machine time |
| Testing | Leak+flow standard; helium/Cert extra | Order certs only where the program requires |
| Batch size | Small runs carry setup | Consolidate; volume pricing at 500+ |
| Logistics | FOB vs DDP; carton vs crate | DDP simplifies import; consolidated saves freight |
Budget guidance: A machined-channel aluminum plate with standard fittings and leak/flow testing is the sensible default and the best value. Move to brazed copper only when flux is extreme or the design demands it, and keep helium leak certification and lapping for programs that explicitly call for them.
Customize Process
From your module drawing to a validated, leak-tested water cooled heat sink. A typical custom cold plate program runs in seven steps - fluid and fitting choices are locked in at RFQ.
RFQ
Module footpring, heat load, flow, pressure, fluid
Thermal Sim
Channel layout+R and pressure-drop estimate
Quote & DFM
Build route, material, fittings, lead time
Sample
Leak-tested sample+flow curve, 7-14 days
Mass Production
Machine/braze, face, ports, clean, seal
QC & Docs
Leak report, flow curve, CoC, RoHS/REACH
For modified standard plates we reuse an existing channel geometry, so leak-tested samples can ship in 7–10 working days. Fully custom brazed cores or copper plates add tooling/braze lead time, which we confirm in the quote.
What Customers Say
M. Hoffmann
Power Electronics Lead, Germany
S. Raman
Hardware Engineer, India
L. Bianchi
Procurement, Italy
FAQ
Q: When should I use a water cooled heat sink instead of an air-cooled one?
A: Move to liquid cooling when power density exceeds roughly 100–150 W/cm², the enclosure is sealed, there is no forced-air budget, or space for fins and a fan does not exist. Below that, a finned or heat-pipe air sink is cheaper and simpler. A liquid cold plate is the option that actually holds junction temperature at high density - it is not a cosmetic upgrade.
Q: What is the difference between a machined-channel and a brazed cold plate?
A: A machined-channel plate has internal paths cut directly into solid aluminum (or copper) and sealed with a cover - simpler, cheaper, ideal for single modules and moderate loads. A brazed core stacks fins or tubes into the plate and vacuum-brazes them, giving higher surface area and lower resistance for very high loads or many parallel devices. We recommend the route from your heat load and layout.
Q: Can you cool with a dielectric fluid instead of water/glycol?
A: Yes. We build plates for both inhibited water/glycol loops and dielectric (including two-phase) fluids. Use dielectric when the loop can contact live parts or you need electrical isolation and two-phase performance. The fluid choice is independent of the plate material and locked in at RFQ.
Q: How do you guarantee the plate will not leak?
A: Every plate is pressure-tested to 2× working pressure (helium or nitrogen hold test) and flow-profiled on a bench rig, with records shipped per batch. Channels are continuity-checked for blockage, fittings are torque-verified, and we issue a CoC. For automotive or energy-storage programs we can provide PPAP-level documentation.
Q: What documentation do you provide with the order?
A: Each batch ships with a thermal simulation report, leak-test record, flow and pressure-drop curve, mounting-face flatness check, material certificate, and RoHS/REACH statement, plus a Certificate of Conformity. STEP and 2D drawings are provided at sample stage.
Q: What is the MOQ and lead time for custom cold plates?
A: Leak-tested samples for modified standard plates ship in 7–10 working days with a low prototype MOQ. Fully custom brazed cores or copper plates add tooling/braze lead time, confirmed in the quote. Volume repeats run on a scheduled basis with tiered pricing for 500+ programs.
Q: Do you make aluminum or copper cold plates?
A: Both. Aluminum is the default - light and low cost with strong thermal performance for most loops. Copper is offered where flux is extreme (SiC, >150 W/cm²) and the extra weight is acceptable. We help you decide rather than pushing the more expensive material.
Related Heat Sink Pages
- Power Module Heat Sink - IGBT/SiC/MOSFET module cooling (air route)
- IGBT Module Heat Sink - IGBT-specific air-cooled cooling
- Aluminum IGBT Heatsink - why aluminum for IGBT cooling
- Skived Fin Heat Sink - high-power air-cooled, energy storage
- Custom Extruded Aluminum Heat Sink - hub for made-to-spec profiles
- CNC Machined Aluminum Heat Sink - precision machining capability
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