With the continuous progress of electronic devices. The overheating risk grows gradually. Thermal management is very important to all the electronics. How to choose the right thermal pad in your products assembling? This article will introduce you to the difference between silicone pads and silicone-free pads and help you make the decision.
What are Silicone Thermal Pads?
Silicone pads are the thermal pad made from silicone elastomer with conductive fillers injection, such as metal oxides or ceramics to improve thermal conductivity. Silicone pads are used to enhance the heat transfer between the electronic component and heat sink.
What are Silicone-Free Thermal Pads?
As the name suggests, silicone-free pads are made from non-silicone polymers. Typically, it used acrylic resin, polyimide or ceramics and other alternative polymers as raw material. Silicone-free pads are designed to solve the silicone pads problems that exist.
What are the Characteristics Difference？
Silicone Thermal Pads
Advantages of Silicone Thermal Pads
High Thermal Conductivity
The biggest advantage of silicone pads is the high thermal conductivity. The thermal conductivity range is very wide from 1.0 to 15 W/m·K. Silicone pads can meet the different requirements about heat dissipation.
Silicone pads can help you achieve the effective heat transfer of cross-interface. If your electronic devices have a strict need for thermal management like electric vehicles, power systems or LED lighting, then silicone pads are suitable for you.
Strong Compressibility
Silicone pads also have a strong compressibility because of the silicone elastomer. The compressibility of silicone pads can reach 90%. The good compressibility means the silicone pads have certain flexibility to adapt the irregular surface of the electronic component to fill in the micro surface defect, air gap and areas with big size change.
Silicone pads can ensure thermal contact effectively and improve the heat dissipation situation of your electronic component.
Electrical Insulation
Silicone pads have the function of electrical insulation. They have low dielectric strength and reduce the risk of electrical interference. Silicone pads can greatly reduce the fire risk. Which means the silicone pads have a big safety and you can use them with low accidents.
Disadvantages of Silicone Thermal Pads
Outgassing Problem
The outgassing problem is a serious issue that happened in all the polymers. Silicone pads are no exception. When silicone pads are in the high temperature of low air pressure, then the outgassing process will be accelerated.
Silicone pads will release the volatile gases that can cause problems during the sealed cavity packing. Outgassing is especially a big problem in aerospace areas like sensitive electronic components or optical components.
Conductive Problem
Silicone pads are conductive under high temperature. The silicone electronics can get away from the silicone covalent bond. The change of chemical structure will cause the silicone electronics to run in the lattice, thus form conductivity.
When there is an exposed electrical connection or in the use of sensitive circuits application, it is better to use silicone pads carefully. The conductivity may cause a short circuit of your electronic devices.
Silicone Oil Migration
Silicone oil migration is also a headache-inducing problem to most silicone pads users. Actually most silicone pads are not pure silicone but use silicone oil as the basic component. After long-term use, the silicone oil will migrate and leak by the working of clamping force.
The silicone oil migration will reduce the contact quantity of material between the electronic component and heat sink, thus preventing the effective heat transfer. The leak of silicone oil will cause pollution and pollute the electric environment.
The silicone oil migration will affect the electronic device appearance to a great extent. If you are doing the auto business including automobile assembly and have a good-looking surface, then silicone pads may need to think it over again.
Silicone-Free Thermal Pads
Advantages of Silicone-Free Thermal Pads
Low Outgassing
From the chemical structure difference from silicone pads, there is no silicone resin in silicone-free pads. The special structure makes the silicone-free pads have a low outgassing possibility. This will help to reduce the pollution of electronic components surrounding and the risk of reduced performance.
According to the international professional outgassing test of silicone-free material, the weight loss is as low as 0.052% when test temperature rises. There is about 0.060% weight loss of silicone-free material under 200℃ baking in 30 mins.
These test data display the volatile substances that silicone-free material reduces are very small when in a high temperature. If you are doing the business of aerospace or semiconductor manufacturing or other high vacuum applications, then silicone-free pads are a suitable choice.
Strong Thermal Conductivity
Although the silicone-free pads are different from silicone pads in chemical structure aspect. But there is still a common advantage of the two pad materials: strong thermal conductivity.
The thermal conductivity of silicone-free pads is about 1.5-8.0W/m·K, as strong as silicone pads. If you want to choose the silicone-free pads for heat dissipation, then you don’t have to worry about its ability.
Electrical Insulation
Silicone-free pads have a perfect electrical insulation performance under a high temperature. The dielectric constant is lower than silicone pads and has a tiny conductive path, thus can reduce the short circuit or leakage risk of the sensitive electronic components.
Eco-friendly
The silicone-free pads are friendly to the environment. It has reached the RoHS, REACH and other environmental standards in the EU. Silicone-free can ensure the safety of electronic components assembly and sustainability development.
Disadvantages of Silicone-Free Thermal Pads
Low Compressibility
The compressibility of silicone-free pads is worse than silicone pads and have a low mechanical flexibility. They are hard to fit the uneven electronic components surface.
Silicone-free pads are hard to achieve the best surface touch and difficult to remove the air gap between heat resource and heat sink. The bad flexibility performance will affect the entire heat dissipation effect.
What are Application Differences?
Silicone pads are better suitable for the assembly of consumer electronic products or LED products. It can deeply reduce the temperature of LED lights and extend the service life. Typical applications include high power density LED modules, power supplies, UPS and so on.
While the silicone-free pads are better in the manufacture of electronic devices sensitive to silicone, such as precision electronics, medical equipment, automotive electronics and aerospace. Typical applications include medical equipment, camera, surveillance equipment.
How to Choose Silicone or Silicone-Free Thermal Pads?
About how to choose the thermal pad between the silicone pad and silicone-free pad, we suggest you consider 5 aspects. They are heat conductivity, electrically isolated, heat resistance, exhaust problems and cost budget.
Usually, silicone pads can withstand high temperature while keeping a strong mechanical properties, it is suitable for harsh environments. Silicone-free pads are suitable for applications that need electrically isolated and low pollution risk.
Generally speaking, if your electronic equipment is sensitive to silicone, then silicone-free pads are the first choice. They have higher performance and stability to avoid the compatibility problem. Otherwise, silicone pads are more affordable to choose.
Conclusion
A suitable TMI material can heat dissipation of electronic devices effectively. Both silicone pads and silicone-free pads have their own benefits to adapt to different situations. If you are still concerned about how to choose, please contact GALLOP INNOTEK. We are an experienced conductive material manufacturer that can offer you professional suggestions on business.
FAQs
Does Silicone have High Thermal Stability?
Yes, silicone has high thermal stability compared to other thermal materials. Silicone has a very low glass transition temperature. Whether the temperature is extremely low or high, it can keep good flexibility. Silicone can withstand temperatures between -60℃ and 200℃.
When switching the electronic equipment, the temperature will change a lot. Also, the season changes will cause temperature differences. Whatever the situation is, silicone can give an excellent response.
What is the Best Material for Thermal Pads?
There are many types of thermal pads with different performance in the market. We cannot say which one is the best. But you can find the most suitable thermal pad for your products.
Silicone is the most commonly used thermal material with good flexibility and temperature resistance, which is suitable for most types of electronic equipment.
Graphite is also a widely used material for thermal pad production. Its thin structure is very suitable for electronics with specific thickness requirements. Graphite thermal pad is a perfect alternative product to high price thermal paste and is easy to install.
Aluminum nitride pads have high conductivity and good electrical insulation performance, thus suitable for high power applications.
Carbon fiber pads also have high conductivity and are suitable for electronic equipment that need effective heat dissipation.
Phase change pads can transfer into liquid from solid in 45-55℃, which means it has great humidity and low thermal resistance. So phase change pads are better to use in CPU, GPU or other power supply applications.
Thermal Gel vs Thermal Pad: Which One is Better?
The selection of TIM(Thermal Interface Materials) type depends on your specific use. If your electronics need a strong connection, then thermal gel is suitable for you. If your electronics need to be maintained or replaced frequently, a thermal pad is a better choice.
