Copper shim and thermal pad are two common thermal interface materials, they have their own advantages and drawbacks. If you are deciding between the two materials, keep reading. This article will deeply analyze the differences between copper shim and thermal pad, telling you which one is suitable.
What Is Copper Shim
Copper shim is typically used in the heat dissipation of electric devices. It can fill the physical gap between heat generating surface and heat chips, making sure the heat can be transferred normally. The high purity copper is produced to thin slices, you can customize it by CNC machine, stamp or laser cut. Precision machined parts are also widely used for complex industrial components. And the surface of copper shim is usually nickel plated to prevent oxidation issues.
What Is Thermal Pad
Thermal pad is a type of flexible polymer composites, it is composed of base materials and thermal conductivity fillers. Common basic material is silicone, and the thermal conductivity fillers include ceramic powder, aluminum oxide, etc. The thermal pad can be designed of different thickness or cutted to various shapes, meeting different device requirements. It offers a certain degree of cushioning when transferring heat to protect components.
Differences Between Copper Shim And Thermal Pad
Thermal Conductivity
As a metal material, copper shim has an extremely high thermal conductivity. It almost does not produce heat loss, and can transfer the heat to the heat sink quickly. It is an ideal material for products with high power and high heat density. While the thermal pad is typically used in low to medium power devices because of its low thermal conductivity. When it is used in high heat density applications such as GPUs, the thermal resistance may be an obstacle.
Assembly Difficulty
It is important for installing copper shims to control the equipment gaps between chips and heat sinks, better to ensure a range in 0.02mm. If the gap is too big, copper shims cannot fill tightly, leading to decrease the efficiency of heat dissipation. In contrast, too small a gap is also difficult to install copper shims. It may provide high pressure to the copper shim, and make a damage failure.
Thermal pad has a feature of compressibility, it can be pressed to adapt the gaps. This can decrease the precision requirement of production, and make the thermal pad suitable for mass production and automated production lines. But if your project is connected with precision manufacturing or small-batch production, the copper shim is more suitable.
Flexibility
The copper shim is usually customized according to different devices, so it has a fixed structure. It has an explicit heat dissipation path, which means the components need to be fixed in the initial stage. Thermal pads allow some degree of adjustment after designing. If the components change, the thermal pad can be replaced or cutted to adapt to the new structure.
Stability
Many equipment will experience temperature change repeatedly, with long term operation, the thermal conductivity performance of materials may be affected. Copper shims have a rigid structure, it is difficult to change shape or age. It offers stable physical properties, and minimal thermal cycling impact. So the copper shim can maintain good performance even in a harsh environment.
While a long time of heat cycling may make the thermal pad become fatigued, gradually lose the pressibility. Issues such as harden, crack, or reduced tackiness may occur, especially in the condition with high temperature, high humidity or shock. But the flexible structure helps thermal pads absorb the stress of thermal expansion and contraction.
Maintenance
The copper shim is typically installed by screws or welding, and is difficult to replace. Due to the durability of copper shims, its maintenance cycle is very long. Once the copper shim has failures, the cost of maintenance is expensive and it is easy to harm surrounding components. You should also pay attention to avoid issues with the installing process, it may have a risk of chip damage or short circuit.
Compared to the copper shim, thermal pads have more flexibility in maintenance. It can be replaced efficiently without any damage to devices. If your equipment requires regular maintenance or upload, the substitutability of thermal pads can greatly reduce the overall cost. The thermal pad has good independence that it will not damage other components when some issues occur.
Insulation
In some industries such as automotive, medicine, consumer electronics, the heat dissipation material not only needs thermal conduction, but also satisfies the standard of insulation to prevent short circuit or other electronic issues. Copper shim has not insulation function, it must to be added insulating gasket or coating to improve material safety, which also increase the complexity of production. The thermal pad naturally possesses electrical insulation properties, it can meet the standards of UL94. So if the products have a requirement of insulation, you can choose thermal pads.
Cost
The overall cost includes material unit price, production, process, transportation, loss and other factors. Raw materials of copper shim have stable prices, but they need complex processing and molds. The thermal pad can be formed by cutting, and the production process is simple. So the copper shim has higher initial investment than thermal pad. However, for long term using, copper shim offers high performance and low maintenance frequency. You can consider the comprehensive factor to choose a better one.
Applications
Copper shims are designed for the applications that have high precision and short gaps between heat source and heat sink. The typical applications include high power consumption, AI servers, high performance computing, etc. The copper shim is used as a core heat dissipation medium to maintain high efficiency thermal conduction. It can significantly reduce the thermal resistance and make the system in a stable condition.
The thermal pad is typically used in medium to low power consumption, smart home devices, automotive control modules and so on. It can prevent electronic failures due to its excellent insulation performance. Thermal pads improve the efficiency of the installation process, and it is easy to maintain, which can decrease your cost.
Choose Between Copper Shim And Thermal Pad
When you choose the thermal materials, you should take all factors into consideration. Ensuring that the ultimate solution can not only satisfy performance requirements, but also meet the long term development goals. The followings for your reference:
- Product Positioning: Premium products prefer performances and stability, you can firstly consider copper shim to improve heat dissipation efficiency. While if your products are likely with common consumer electronics, thermal pads can decrease the cost and achieve mass production.
- Production Management: The copper shim requires high precision process and strict size control, it is suitable for automated production or other stable production lines. Thermal pads are easy to install and manage, they are more suitable for applications that need frequent adjustment.
- Maintenance Strategy: If your project does not need frequent maintenance, such as communication base stations or industrial controllers, the copper shim is better. But for the device that requires regular maintenance, the thermal pad can be easy to replace or repair, which can decrease your cost.
- Regulatory Compliance: Some special industries have a strict demand about insulation and flame-retardant, thermal pads will provide good performance in these industries. If you must use copper shims, adding insulation design to make sure they can meet the standard.
- Return on Investment: Your decision should a comprehensive evaluation include manufacturing inputs, repair rates, overall cost and customer satisfaction, etc. Targeted at different products to analyze the ROI, and choosing a suitable material.
Conclusion
It is difficult to determine which one is the best between copper shims and thermal pads. Different equipment have difficult requirements, so you should choose a suitable one according to the actual production. If you have any other questions about these thermal materials, feel free to contact us for a professional solution.
FAQs
1.Can the copper shim and thermal pad be used together?
Yes. In many high performance devices, one type of thermal material cannot meet the requirement of heat dissipation. The copper shim is typically used in the core high heat area, minimizing thermal resistance and maximizing efficiency. While the peripheral area or large structural tolerances components are filled by thermal pads, it can simplify the process and reduce the cost. This solution can balance performance and cost, reducing the maintenance cost.
2.How copper shims achieve insulation?
Copper is a highly conductive material. If it directly contacts chips or electric components, it may cause safety issues. A common method to achieve insulation is making insulating coating or nickel plating on the surface of copper shims. Or you can add an insulating film or mica sheets between the copper shim and chips. In the process of structure design, reserving a part of the space to separate the copper shim.
