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Views: 5 Author: Site Editor Publish Time: 2026-01-23 Origin: Site
Pumping coolant through a metal block is easy; ensuring that coolant extracts maximum heat from a 100kW inverter without creating a pressure bottleneck is an engineering challenge. In high-power electronics cooling, the difference between a system that runs efficiently and one that throttles lies in the geometry of the fluid path.
For product designers and procurement managers, understanding the architecture of Multi-pass liquid cold plate design is essential. It is not just about the material; it is about how the fluid moves.
At Kingka Tech, we have spent over 10 years refining liquid cooling solutions. From simple 2-pass embedded tube designs to complex 4-pass friction stir welded (FSW) assemblies, we provide a one-stop solution—from thermal analysis to final testing. Below, I will break down how to optimize thermal performance in multi-pass cold plates and the manufacturing technologies that make them reliable.
The Single-Pass Limitation: Why We Need Multi-Pass Architectures
Manufacturing Reliability: The Role of Friction Stir Welding (FSW)
Why isn't a straight line always the shortest distance to thermal efficiency?
In a simple single-pass cold plate, coolant enters, heats up as it travels across the heat source, and exits. This creates a significant "thermal gradient" across the plate. The components near the inlet stay cool, while those near the outlet risk overheating.
Liquid cold plate thermal performance relies on uniformity. By implementing a multi-pass design (serpentine or parallel paths), we increase the total length of the tube within the active cooling zone. This ensures that a larger surface area of the coolant interacts with the heat source, smoothing out temperature gradients and allowing for higher total heat rejection for High power electronics cooling.
How do we determine the right tube layout?
Designing a flow path is a balancing act. At Kingka Tech, our engineering team uses CFD (Computational Fluid Dynamics) to simulate flow velocity and heat transfer before manufacturing begins.
We look at two main configurations:
Serpentine (Continuous Loop): Excellent for ensuring equal flow velocity throughout the plate. Ideal for ensuring every IGBT or MOSFET gets the same cooling attention.
Parallel (Manifold): Reduces pressure drop but risks flow imbalance if not designed carefully.
Kingka Tech Experience:
We tailor the loop count to the specific heat footprint. For concentrated heat sources, a multi-pass dense loop is required. For distributed loads, a wider spacing may suffice. This customization is central to our engineering capability.
What does a high-performance solution look like in practice?
Consider one of our flagship configurations: the 4 Pass Copper Tube FSW Liquid Cold Plate.
The Challenge: A client required cooling for a high-density power converter where a standard 2-pass loop left "hot spots" in the center of the module.
The Solution: Kingka Tech designed a 4-pass copper tube layout embedded into a base plate.
The Technology: We utilized Friction Stir Welding (FSW) to seal the assembly. Unlike standard pressed tubes, FSW creates a metallurgical bond that integrates the cover and base, ensuring the tubes are locked in position with maximum structural rigidity.
The Result: The 4-pass design doubled the internal surface area available for heat transfer, significantly lowering the junction temperature of the power modules.
The tube is round, but the plate is flat. How do we solve the gap?
One of the biggest killers of thermal performance in tube-based cold plates is the gap between the round copper tube and the channel it sits in. Air is a thermal insulator.
To solve this, Kingka Tech utilizes Hi-Contact Technology (often applied in our Liquid Cold Plate with 2 Pass Copper Tube designs).
The Process: Instead of simply gluing a round tube into a round groove, we use high-pressure pressing or swaging to flatten the tube surface so it is flush with the mounting surface.
The Benefit: This eliminates the layer of epoxy or aluminum between the coolant tube and the heat source. The heat source contacts the copper tube directly.
Impact: This dramatically reduces thermal resistance ($R_{th}$), making even a simple 2-pass design highly effective for mid-range loads.
How do we ensure the coolant stays inside the plate?
Leakage is the nightmare scenario for any data center or industrial operator. Traditional methods like epoxy bonding can degrade over time due to thermal cycling (heating up and cooling down repeatedly).
Kingka Tech's Copper FSW Liquid Cold Plate represents the gold standard in reliability.
Process: FSW uses a rotating tool to plasticize the metal, joining the channel cover to the base without melting it.
Advantage: This creates a joint that is as strong as the base material itself. It is impervious to vibration, high pressure, and thermal shock.
Application: We recommend FSW for any High power electronics cooling application where reliability is non-negotiable, such as in electric vehicles or critical power grid infrastructure.
Can we balance performance with weight and cost?
Material selection drives both the thermal performance and the budget. Kingka Tech supports a wide range of material combinations:
All-Copper: Best for maximum conductivity. Our Copper FSW Liquid Cold plates are used where heat flux is extreme.
Copper-Aluminum Hybrid: This is the most popular choice for "Tube-in-Plate" designs. We embed Copper tubes (for coolant compatibility and heat transfer) into an Aluminum base (for lightweight structure and mounting).
Engineering Note: When using hybrids, we ensure the mechanical fit is tight to prevent galvanic corrosion issues, often recommending specific coatings or inhibitors in the coolant.
How many passes are too many?
Adding more passes (e.g., going from 2-pass to 6-pass) improves thermal uniformity, but it increases the pressure drop ($\Delta P$). If the pressure drop is too high, your pump may not be able to maintain the required flow rate, or it will consume excessive energy.
Decision Guide:
Low Flow / High Efficiency: Use more passes with slightly larger tube diameters.
High Flow / Low Pressure: Use fewer passes or parallel loops.
At Kingka Tech, we don't just guess; we calculate. We help you find the "sweet spot" where Liquid cold plate thermal performance is maximized without exceeding your pump's capacity.
Optimizing Multi-pass liquid cold plate design is about more than just routing pipes. It requires a deep understanding of contact mechanics (Hi-Contact), manufacturing integrity (FSW), and fluid dynamics.
Whether you need a robust 4 Pass Copper Tube FSW solution for a heavy industrial load or a cost-effective 2 Pass design for a standard server, the key is customization.
Kingka Tech brings over a decade of engineering experience to the table. We don't just manufacture to print; we partner with you to optimize the flow path, select the right materials, and validate the reliability of the final product.
