Introduction of some relevant knowledge about silicon nitride sheet


Release time:

2021-11-02

Silicon nitride sheet is the heat dissipation substrate for high-power devices and LED high-power packaging. It is based on the high thermal conductivity of silicon nitride sheet, which can reach more than 170 watts, which is more than 5 times that of alumina ceramic substrate and 100 times that of ordinary PCB, far exceeding the heat dissipation capacity of copper substrate, aluminum substrate and PCB.

The silicon nitride plate is metallized by the silicon nitride plate, which has better thermal conductivity.

The silicon nitride sheet is processed from a silicon nitride sheet. After surface treatment such as copper plating, silver plating, gold deposition and silver deposition, the thermal conductivity is stronger, so it has better electrical properties. Since the silicon nitride plate is made of a ceramic substrate and the crystal is AIN, its hardness is higher than that of alumina, and it is thermally conductive and insulated. It is a "hot cake" in the field of heat dissipation ".

More and more high-power devices, modules and LED packaging to silicon nitride sheet.

As far as LED packaging is concerned, the production process of ceramic plates in previous years is immature, the cost is very expensive, and it cannot keep up with market demand. It has to use copper substrates, aluminum substrates and other metal substrates for heat dissipation. Using aluminum substrate or copper substrate to dissipate heat, due to insufficient thermal conductivity, it is easy to cause a lot of heat and heat, and it is easy to burn out the circuit, resulting in abnormal operation of the device. The aluminum nitride ceramic heat dissipation substrate has high thermal conductivity, low expansion coefficient, dielectric loss and insulating material, which can make the device work for a long time with less loss and maintenance pressure.

Visible, silicon nitride plate is a good heat dissipation substrate. Although the manufacturing cost is high, the overall performance is stable. In the long run, using silicon nitride sheet heat dissipation is a wise choice. The silicon nitride plate adopts mature thin film circuit technology or AMB technology, which can realize precision circuit, solid copper filling hole and dam. In addition to surface treatments such as gold deposition, silver deposition, copper plating and copper plating, it can also be made of gold-tin alloy and platinum.

When silicon nitride sheet manufacturers package ceramics and metals, they must first complete the metal packaging structure through design. So, how is the ceramic metal packaging structure designed? What are the design principles?

1. The primary expansion coefficient of the metal parts and ceramic parts of the ceramic metal seal inoculation should be consistent or close, and the difference between the whole area from room temperature to the welding temperature should be within 7% ~ 10%.

2. Low elastic modulus low yield limit principle. In mismatched seals, a low modulus of elasticity should be selected due to large differences in thermal expansion. Metal materials with low yield limit are classified as oxygen-free copper as parts.

3. Since the tensile strength of ceramics is about one-tenth of the compressive strength, it is necessary to apply stress to the ceramics as much as possible when designing sealing parts. For example, for stainless steel with high strength and high linear expansion coefficient, the outer sleeve sealing structure should be adopted.

4. The thermal conductivity is close to the principle. When choosing the mating material, the thermal conductivity of the two materials should be close, which is beneficial to the thermal stress of the small sealing parts.

5. Stress reduction principle Under the premise of ensuring that the butt joint has sufficient strength, the metal thickness on the sealing surface should be thinned as much as possible to release part of the pressure. For example, the metal thickness on the sealing surface is usually 0.5 to 1.0mm, and the tubular tube is better than the strong needle.