In - depth Analysis: The Impact of Oil Leakage Rate on Thermal Conductive Silicone Sheets

In the tide of modern technology, various electrical devices have become an indispensable part of people's lives and work. However, a common problem plagues everyone - device overheating. When electrical energy is converted into other forms of energy, it cannot achieve 100% efficient conversion. Inevitably, a part of the energy is lost in the form of heat. Whether it is a commonly used computer, mobile phone, or other complex electrical equipment, the continuous accumulation of heat may lead to a decline in device performance and even cause damage to the device in severe cases.

In the early days, people attempted to solve this problem by installing heat sinks on the surface of heat sources. However, the effect was not satisfactory. Through in - depth research, it was found that the key lies in the gaps between the heat source and the heat sink. These gaps are filled with air, and air, being a poor heat conductor, greatly hinders the effective transfer of heat to the heat sink. To improve the heat dissipation effect, filling a thermal conductive material between the heat source and the heat sink has become an inevitable choice, giving rise to thermal interface materials.

Thermal conductive silicone sheets, as a widely used type of thermal interface material, play an important role. They are usually made with silicone resin as the base material, added with high - temperature - resistant and thermal - conductive materials. Their main function is to fill the gaps between the heat source and the heat sink. Thermal conductive silicone sheets possess many excellent properties, such as high thermal conductivity, low interface thermal resistance, good insulation, and excellent compressibility. Due to their soft texture, they can exhibit a low thermal resistance under low pressure. They can also effectively expel the air between the contact surfaces and fully fill the rough contact surfaces, thus significantly enhancing the heat conduction effect. Thanks to their good filling performance, they can not only efficiently transfer the heat of the heat source to the outer shell, but also act as shock - absorbing pads due to their excellent compressibility and elasticity.

When selecting thermal conductive silicone sheets, it is necessary to comprehensively refer to multiple parameters to determine whether they meet the standards. Among these, the oil leakage rate is a crucial indicator. Many people are very concerned about the oil leakage rate of thermal conductive silicone sheets. But what exactly is the oil leakage rate, and what impact does it have on the performance of thermal conductive silicone sheets?

In fact, the oil - leakage phenomenon of thermal conductive silicone sheets is normal. This is because during the production process of thermal conductive silicone sheets, silicone oil is usually mixed with thermal - conductive, heat - resistant, and insulating materials in a specific proportion and then processed through special equipment. During this process, there are often some free small molecules in the finished product that have not fully combined with other substances. When exposed to high - temperature or high - pressure environments for a long time, these small silicone - oxygen - containing molecules will gradually precipitate, which is the reason for the oil leakage of thermal conductive silicone sheets.

However, if the oil leakage rate of the thermal conductive silicone sheet is too high, the precipitated small silicone - oxygen - containing molecules may adhere to the surface of the heat sink or the heat source, and may even penetrate into the circuit board, which will have a negative impact on the stability and reliability of the device. Therefore, controlling the oil leakage rate is an important criterion for evaluating the performance of thermal conductive silicone sheets.

In addition to the oil leakage rate, the thermal conductivity of thermal conductive silicone sheets is also a key indicator. Here are several common test methods for thermal conductivity:

1. Hot - Plate Method: Place the thermal conductive silicone sheet between a hot plate and a cold plate. The hot plate is maintained at a constant high temperature, and the cold plate is maintained at a constant low temperature. By measuring the heat transferred from the hot plate to the cold plate within a certain period of time, and combining parameters such as the thickness and area of the silicone sheet, the thermal conductivity of the thermal conductive silicone sheet is calculated using the heat conduction formula. This method is relatively simple to operate. However, since the contact conditions between the hot plate and the cold plate in actual use differ from the real - world environment, it may have a certain impact on the test results.
   
2. Laser Flash Method: The surface of the test sample is heated instantaneously by a laser on one side, causing the surface temperature of the sample to rise rapidly. The temperature change on the other side of the sample is measured by an infrared detector. According to the temperature - time curve, combined with parameters such as the thickness of the sample, the thermal diffusivity of the thermal conductive silicone sheet is calculated. Then, by combining with data such as specific heat capacity, the thermal conductivity can be further obtained. The laser flash method has the advantages of fast testing speed and high measurement accuracy, but the equipment cost is relatively high.
   
3. Steady - State Method: Keep the thermal conductive silicone sheet in a stable heat - flow state. By measuring the temperature difference and heat - flow density on both sides of the sample, the thermal conductivity is calculated according to Fourier's law. The advantage of the steady - state method is that the test results are relatively accurate and can reflect the thermal conductivity of the material in actual use. However, the testing time is long, and it takes a long time to reach a stable state.
   

So, how to test the oil leakage rate of thermal conductive silicone sheets? A common test method is to install the thermal conductive silicone sheet sample to be tested in a special test fixture and then place it in a high - temperature test chamber to simulate its long - term heating and pressure - bearing state in the actual working environment. After a period of heating and pressurization, the sample is taken out, and the oil leakage rate is evaluated by measuring the amount of oil on its surface. There are corresponding standards for the oil leakage rate of thermal conductive silicone sheets. Products with an oil leakage rate lower than the standard are considered qualified, while those higher than the standard are unqualified. Therefore, when purchasing thermal conductive silicone sheets, purchasers can request suppliers to provide test reports or conduct actual - machine tests by themselves to ensure that the product quality meets the requirements.

In conclusion, the oil leakage rate and thermal conductivity are key factors affecting the performance and reliability of thermal conductive silicone sheets. A reasonable oil leakage rate helps to maintain the stable performance of thermal conductive silicone sheets, while an excessively high oil leakage rate may pose potential risks to the reliability of the device. At the same time, accurately understanding the thermal conductivity of thermal conductive silicone sheets is crucial for ensuring the heat dissipation effect and long - term stable operation of electronic products. Having an in - depth understanding of and effectively controlling the oil leakage rate of thermal conductive silicone sheets, as well as correctly testing their thermal conductivity, are important links in the selection and use of thermal conductive silicone sheets.