Publish Time: 2023-12-01 Origin: Site
Heat sinks are one of the most fundamental components in cooling electronic equipment. For any heat source that cannot be properly cooled by its own conductive cooling and requires more efficient cooling than a heat sink, a heat sink is required to move the heat away from the heat source and dissipate it through more optimized conduction or convection.
The radiator mainly consists of a base and fins. The base is usually the flat surface that is in contact with the heat source and spreads the heat from the hot spot to the fins. Fins can be cut or constructed into any number of geometric shapes, which are usually perpendicular to the base to spread heat. The goal is to optimize the surface area of the heat sink so that the most heat is transferred and dissipated.
With rare exceptions, heat sinks are made of thermally conductive metal, most commonly aluminum. With a thermal conductivity of 235 W/Kelvin per meter, aluminum is lightweight and inexpensive, making it ideal for lighter, more cost-effective radiators. Copper is also a popular choice. Although copper is more expensive and heavier, it may be necessary for high-performance applications due to its high thermal conductivity of 400 W/mK.
Finally, engineers typically classify heat sinks as having "natural" convection or "forced" convection. Natural convection (passive) heat sinks maximize surface area and conduct heat without adding active components. Forced convection (active) radiators are designed to use components such as fans and blowers to force cooler air across the fins, creating turbulence and increasing the radiator's cooling performance.
Board-level heat sinks can be stamped or extruded. Stamped radiators are made from sheet metal that undergoes a progressive stamping process, where each metal stamping adds detail and functionality as it passes through the stamping die. Stamped heat sink geometries are designed for specific electronic package types to ensure optimal fit and functionality on the PCB. These heat sinks can be passive or active, based on the addition of fans, which are often used to increase airflow throughout the board or system.
Advantage:
a.Ideal for low power applications (0-5W)
b.Options for quick and easy assembly
c.low cost
d.Scalable large capacity
e.Catalog options for all packaging types
Shortcoming:
a.Not suitable for applications above 5W
b.Size limit, no larger than 50mm
c.Can only be used on one device - cannot be used to cool multiple heat sources
Extruded aluminum is one of the most popular and cost-effective manufacturing methods. Extruded radiator sizes vary by application, ranging from smaller for board-level applications to larger for mid-power applications. They can be designed for passive or active cooling depending on fin shape and spacing. Board-level extruded heat sinks are common in packages such as BGAs and FPGAs.
Choosing the right extruded heat sink depends largely on the desired form factor. Extruded heat sinks are made by creating a profile mold that determines fin density, spacing and length, as well as base height and width. The softened aluminum is pushed into the mold to form a long rod, called a raw rod, with the same profile and dimensions as the mold. The bars are then cut into smaller standard shaped bars/rectangles or custom lengths. These are further machined and finished to create custom radiators. The process is fast, cost-effective, and scalable; which is why many people consider extruded heat sinks first when looking for a solution.
Advantage:
a.Ideal for low to medium power applications
b.Fast and cost effective
c.Scalable large capacity
d.Simple customization
e.One-piece construction with limited thermal resistance
Shortcoming:
a.Not suitable for high power applications
b.Size restrictions: no larger than approximately 23 inches wide by 47 inches long
c.Finishing limitations for larger sizes
Skiving is a method of machining materials made from a single piece of metal in which the layers are sliced from the top portion of the base. The layers are folded up perpendicular to the base, and the process is repeated periodically to create the fins. One-piece construction reduces thermal resistance because there are no seams or material between the fins and base. The process also enables high fin density and thin fin geometries, resulting in greater heat sink surface area and improved heat transfer performance.
Unlike extruded heat sinks, skived fin heat sinks do not rely on tools and multiple steps; instead, they use a cutting tool, resulting in lower tooling costs, increased design flexibility, and faster prototyping.
Advantage:
a.More efficient cooling and better performance
b.Thin fins and high fin density capabilities
c.Reduce mold costs
d.Economical copper manufacturing
Shortcoming:
a.Not suitable for high power applications
b.size limit
c.Thin fins may be more fragile
d.Not conducive to large quantities
A bonded fin heat sink is a two-piece assembly consisting of an extruded or machined base with grooves or troughs and fins that are bonded with a thermally conductive adhesive, usually a ring oxy resin or welding) connection. To improve structural integrity and thermal performance, these structures are sometimes brazed to enhance thermal and mechanical bonding.
The fins are usually stamped from coil stock or cut from thin sheet stock, while the base is usually extruded, die-cast or machined. Bases may also include additional thermal integration, such as embedded heat pipes or vapor chambers, for even higher performance. By supporting more and longer fins and additional customization, bonded heat sinks provide higher performance and greater surface area in a smaller footprint.
Advantage:
a.Smaller footprint, ideal for space-constrained applications
b.High thermal performance
c.Suitable for forced convection, no limit on airflow length
d.Close fin spacing
e.High fin aspect ratio
f.Easy to integrate and high design flexibility
g.Reduce mold costs
Shortcoming:
a.Not suitable for high vibration or shock applications
b.It cannot be used when the thermal resistance is required to be lower than 0.01°C/W.
The zipper fin stack is made from a series of individual stamped sheet metal fins that fold and zip together using an interlocking feature. Fin lengths and gaps vary depending on the stamping die. The fins can be closed to form finned ducts or left open for multi-directional airflow depending on application requirements. Fin stacks are often welded, brazed or epoxy to the heat sink base or heat pipe to achieve a complete thermal assembly. The connection of the top and bottom fins increases mechanical stability and makes the heat sink more durable. Zipper fin stacks offer a high degree of design flexibility and can be used in highly integrated solutions using a range of technologies from embedded and transport heat pipes and vapor chambers to fans and large systems.
Advantage:
a.High thermal performance
b.Ideal for forced convection
c.Easy to integrate and high design flexibility
d.Reduce mold costs
e.lighter weight
f.Can be used to improve heat pipe efficiency
g.Improve mechanical integrity
Shortcoming:
Some limitations of low thermal resistance requirements
Folded fins are constructed by putting metal sheets through a folding process to create a variety of geometric shapes with greater surface area. Although these fins can be used in a range of technologies, including liquid cold plates; they are often bonded or soldered to a base to form a heat sink.
Advantage:
a.Increased surface area and fin efficiency
b.High heat flux density
c.More material options
d.light weight
Shortcoming:
a.Best when air is piped directly to the radiator
b.May incur higher costs
The die casting heat sink is a one-piece structure. They are primarily intended for high-volume production in applications that are weight-sensitive, require excellent surface quality, or have highly complex geometries. These solutions are achieved by pouring a thermally conductive alloy into a near-net shape custom mold, then lightly machining and finishing to obtain the final product.
Advantage:
a.Ideal for high-volume, high-performance applications
b.Suitable for complex geometries
c.Low or no thermal resistance
Shortcoming:
High initial one-off mold cost
For diversified heat sinks, Winshare Thermal Energy has professional customization capabilities and diversified application markets, and can customize cooling products for different systems for customers. In the meantime, we will take many factors into account when designing the radiator and continue to optimize and improve the design of the radiator. If you have any other questions about heat sinks or need a cooling solution suitable for your business, please feel free to leave a comment or contact Winshare via email.
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