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Heat Dissipation Principle

Heat dissipation refers to the process by which thermal energy transfers from a region of higher temperature to one of lower temperature, primarily through conduction, convection, and radiation.
Fourier’s law of heat conduction states that the conductive heat flux is proportional to the negative temperature gradient: q=−k∇T, where k is the material’s thermal conductivity.
Newton’s law of cooling describes convective heat transfer, stating that the rate of heat exchange between a surface and the surrounding fluid is proportional to their temperature difference: q = h A (Ts - T∞ ), where h is the convective heat transfer coefficient.
The Stefan–Boltzmann law states that the total radiant power emitted per unit area by a blackbody is proportional to the fourth power of its absolute temperature: q=σT4, where σ is the Stefan–Boltzmann constant.
These three laws correspond respectively to the fundamental heat transfer mechanisms—conduction, convection, and thermal radiation—and form the theoretical foundation for engineering thermal management and design.

What Is Heatsink？

A heatsink is a thermal management device designed to rapidly conduct and dissipate heat generated by electronic components, mechanical equipment, or other heat sources into the surrounding environment. Its primary purpose is to control temperature, prevent overheating, and ensure stable system operation. The fundamental principle of a heatsink is to reduce the thermal resistance between the heat source and the ambient environment. According to heat transfer theory, this can be achieved through three main approaches: shortening the heat transfer path, using materials with high thermal conductivity, and increasing the heat dissipation surface area. Common types of heatsinks include air-cooled fin stacks, vapor chambers, and liquid-cooled channels, which are widely used in applications such as computer CPUs/GPUs, power supply modules, LED lighting, electric vehicle power electronics, and industrial equipment.

Heatsink Structure

The structure of a heatsink typically consists of several core components. While different types of heatsinks may vary in specific forms, their basic construction principles are similar:

Base

Function: Directly contacts the heat source (such as a CPU or power device) and is responsible for rapidly absorbing and conducting heat.

Materials: Usually made from high thermal conductivity metals like pure copper (with a thermal conductivity of about 400 W/m·K) or aluminum alloy (about 200 W/m·K).

Requirements: High surface flatness to reduce thermal contact resistance between the heat source and the base; sometimes integrates heat pipes or vapor chambers to enhance lateral heat conduction.

Fins

Function: Increases the contact area with air (or cooling medium), enhancing convective cooling efficiency.

Forms: Can be parallel straight fins, pin fins, wavy fins, etc., with density, height, and thickness designed according to cooling requirements.

Materials: Typically the same as the base, but can also use a "copper base with aluminum fins" combination to balance performance and cost.

Heat Spreading Structures (Optional)

Heat Pipe: Utilizes phase change of internal working fluid to achieve efficient long-distance heat transfer, often embedded in the base to connect distant fins.

Vapor Chamber: A two-dimensional plane or 3D cavity structure that achieves rapid temperature uniformity over a large area, suitable for high heat flux scenarios.

Thermal Interface Material (TIM)

Function: Fills microscopic gaps between the heat source (such as a chip) and the heatsink base, displacing air (which has poor thermal conductivity), significantly reducing thermal contact resistance.

Types: Includes thermal paste, thermal pads, phase change materials, thermal gels, metal solders (like indium), etc., chosen based on application needs for different thermal conductivities, hardness, and reliability levels.

Mounting & Interface Structures

Includes screw holes, clips, spring plates, etc., used to securely mount the heatsink onto the heat source and ensure good contact.
Some high-end heatsinks integrate fan mounts, anti-vibration pads, or pre-applied thermal paste.

Surface Treatment (Optional)

Such as anodizing (to improve corrosion resistance and emissivity), nickel plating (to prevent oxidation), black coating (to enhance thermal radiation), etc., optimizing both thermal performance and appearance.

Heatsink Performance

Objective	Theoretical Method	Practical Method	Limiting Factors
Reduce thermal resistance	reduce conduction distance	Reduce substrate thickness Thinner thermal pad	1. Process: For heat sinks of different processes, the substrate thickness is not less than 1mm 2.Structural strength: A substrate that is too thin can cause deformation of the heat sink when it is locked in place 3.Flatness: Thin substrates have higher requirements for flatness
	Increase thermal conductivity	Select materials with higher thermal conductivity	1. Weight: Copper has a density 3.3 times that of aluminum, and the weight of copper fins is 3.3 times that of aluminum fins 2.Cost: The price of copper is 3.5 times that of aluminum, and the material cost of copper fins is 11.55 times that of aluminum fins
	Increase heat transfer area	Increase fin count and height Fully utilize heat dissipation space	1.Process: skiving > extrusion = stamping fin 2.Cost: extrusion < stamping fin < siving 3.Pressure drop: Increased fin density leads to increased pressure drop, reduced airflow, and reduced heat dissipation efficiency under certain conditions

Heatsink Manufacturing Methods

Extrusion

The process involves forcing heated aluminum ingots through a die under high pressure to form continuous finned profiles, which are then cut and surface-treated to create heatsinks. Suitable for mass production with low costs, but the thickness and spacing of fins are limited by the process, making it difficult to achieve ultra-high density.

Skiving

Utilizes high-precision tools to "shave" dense, thin, and tall fins from a solid block of copper or aluminum, forming an integrated base and fin structure. This method eliminates interface thermal resistance and offers excellent thermal performance, ideal for high heat flux applications. However, material utilization is low, leading to higher costs.

Stamping

Involves cutting, bending, or forming metal sheets using presses and dies, commonly used to produce thin fins or bracket structures. It is efficient and suitable for large-scale production but often requires additional processes (such as clinching or welding) to assemble complete heatsinks.

Die Casting

Molten aluminum or zinc alloy is injected into a precision mold under high pressure to form complex three-dimensional heatsink bodies in one step. It allows for intricate geometries and integrated structures, suitable for mass production. However, internal porosity may occur, resulting in slightly lower thermal conductivity compared to pure extruded aluminum.

CNC Machining

Uses computer numerical control machines to mill, drill, and otherwise process metal blocks, enabling the creation of high-precision, customized heatsink structures (such as liquid cooling channels or irregular fins). Highly flexible and precise, suitable for prototypes or small batches of high-end products. However, it has long processing times, high costs, and significant material waste.

Brazing / Soldering

Joins fins to the base or other components by melting brazing or soldering materials at high temperatures. Commonly used in assembling copper-copper or aluminum-aluminum heatsinks. This method achieves strong bonding and good thermal conductivity but requires careful control of thermal deformation and strict cleanliness and process standards.

Friction Stir Welding (FSW)

Generates frictional heat at the joint using a high-speed rotating non-melting tool, causing the metal to flow plastically and form a solid-state bond. Particularly suitable for large-area, high-strength, low-deformation welding of aluminum alloy heatsinks, with joint thermal conductivity close to that of the base material. Widely used in liquid cold plate manufacturing.