Heat sinks are crucial components in electronic devices, allowing for proper heat transfer and dissipation during operation. They are mostly made from aluminum alloys, copper, bronze or brass, and can be made into multiple design shapes to support its efficiency. Factors like thermal conductivity, weight and price all come into the considerations for making heat sinks. In today’s article, we explore the most common heat sink materials, and 6 most common types/methods of making heat sinks.
Aluminum vs Copper
From an energy and thermodynamic standpoint, the thermal conductivity of the material is the most crucial factor in making heat sinks. Aluminum heat sinks are the most common heat sinks on the market. This is because they are affordable and sufficient enough to meet basic heat dissipation needs. Extruded aluminum is often used as it fits the needs of most projects. The overall design of the device also benefits from the light weight of the aluminum material.
Copper heat sinks are equally common in high performance devices. The benefits of copper over aluminum lies in its better thermal conductivity. Copper, however, is heavier and more expensive than aluminum. It is also more challenging to process and oxidizes more easily than aluminum.
Making Electronic Heat Sinks
Electronic heat sinks can be made using a variety of methods. The most common techniques deployed include extrusion, casting, CNC machining, 3D printing, forging, skiving and stamping. The choice of technique depends on factors like cost and geometric complexity of the design.
• Aluminum Extruded Heat Sinks
Aluminum extrusions are the most common and most effective types of heat sinks on the market. They are very versatile, ranging across high and low performance applications. Extruded heat sinks are relatively easier to make as they can easily be made to custom specifications. The downside of aluminum extrusion lies in the limitation of the heat sinks to the dimensions of the extrusion.
• 3D Printing
While metal 3D printing is not as widespread as other materials, additive manufacturing can be used for rapid prototyping or quick iteration of heat sink designs. It is particularly suitable for low-volume prototyping of heat sinks with complex shapes and geometries. Metal 3D printing is also a feasible solution, using aluminum, bronze or copper to make heat sinks for more detailed prototypes or direct end usage.
• Die Casting
Die casting is very potent for making heat sink designs with complex geometries and very thin walls. It can be used with both aluminum, bronze, copper and other materials. Die casting is particularly cost-effective, and is one of the best choices for making large volumes of heat sink.
Forged heat sinks are used to make high volume of heat sinks at low cost. Forging may be hot or cold forging. The process is executed at high pressure and low temperature, giving the final heat sink great structural integrity and good performance. Forged heat sinks however, face some design limitations.
Skived heat sinks are high-performance heat sinks made from copper. They are used in applications that are not cost-sensitive, and can achieve a high degree of complexity in their design. Skiving creates increased surface area, enhanced heat dissipation, improved design flexibility and achieves high fin density. The drawback for skived heat sinks lies in their directional sensitivity and higher weight from copper usage.
Stamping is achieved through sheet metal processing. These heat sinks are made by stamping and soldering metal fins to the ground. The process is good for making heat sinks that are needed for low-performance applications, and tall heat sinks that host heat pipes within their fins. Stamped heat sinks are relatively easy to produce, and have low landing costs. The downside is in their performance and application limits.
• CNC machining
CNC machining is perfect for making heat sinks with the most complex geometric designs at quick speeds and high efficiencies. The thermal conductivity achievable with CNC machining also makes it one of the most effective production techniques. This high cost downside thus limits CNC to high-efficiency models and occasional uses as mass production is likely to impact business costs and profitability.