Silicon nitride Sheet is a man-made compound synthesized through several different chemical reaction methods. Due to its even performance at high temperatures, Si3N4 is a commonly used ceramic material in the metallurgical industry. It has excellent thermal shock resistance due to the microstructure. The creep and oxidation resistance of Si3N4 is also superior, its low thermal conductivity and high wear resistance also make it an outstanding material that can withstand conditions of most industrial applications.

Silicon nitride ceramics Performance

Item

Unit

Si3N4

Type

Gas pressure sintered

Density

g/cm3

3.2-3.3

Color

Black, Grey

Young Modulus

GPa

300~320

Vickers Hardness

GPa

15 – 17

Compressive Strength

MPa

2200

Bending Strength

MPa

600-1000

Thermal Conductivity

W/m.K

20-30

Thermal Expansion

10-6/°C

3.2

Max. Working Temp.

°C

1200

Volume Resistivity

Ω ·cm

> 1014

Dielectric Constant

6

Dielectric Strength

kV/mm

12

Fracture toughness

MPa·m1/2

5.0-7.0

*Tested at room temperature

*The above information is for comparison only. The exact characteristics will vary depending on the manufacturing method.

Typical characteristics of silicon nitride ceramic

-High strength over a wide temperature range

-High fracture toughness

-High hardness

-Outstanding wear resistance

-Low thermal expansion and high thermal conductivity

-Good thermal shock resistance

-Good chemical and oxidation resistance

Application of silicon nitride ceramics

In addition to superior mechanical properties, silicon nitride ceramics also exhibit a range of excellent thermal conductivity properties, making them suitable for use in the demanding semiconductor field. In the field of integrated circuits, the level of integration and power is constantly increasing, which places higher requirements on the bending strength, stability, and heat dissipation capabilities of the substrates for packaging chips.

Silicon nitride ceramic substrates have high thermal conductivity (typical values for commercial products are 80 to 90 W/mK). Compared with alumina substrates or ZTA substrates, its thermal conductivity is more than three times higher, and its thermal expansion coefficient (2.4ppm/K) is small, close to semiconductor chips (Si, SiC), and has good thermal matching.

In addition, silicon nitride ceramic substrates have excellent mechanical properties, taking into account high bending strength and high fracture toughness. Compared with the alumina matrix or aluminum nitride matrix, it has more than twice the flexural strength, the flexural strength is 600~850MPa, and the fracture toughness is 5~7MPa·m½, so it has extremely high resistance to cold and hot shocks (extremely high reliability) and can weld very thick copper metal (up to 800μm thick) to relatively thin silicon nitride ceramics. Therefore, the current carrying capacity is high and the heat transfer is good. Due to the excellent performance of silicon nitride substrates, it has good application prospects in power modules (IGBT/SiC power modules) such as rail transit, wind power, photovoltaics, and new energy vehicles.

Silicon nitride ceramic sheet production process

Utilizing the nature of Si3N4 decomposition temperature increases (usually in the N2 = 1 atm air pressure, from 1800 ℃ decomposition), in the temperature range of 1700-1800 ℃ for atmospheric pressure sintering, and then in the temperature range of 1800-2000 ℃ for air pressure sintering. The purpose of this method is to promote the densification of Si3N4 ceramics through pneumatic pressure, thereby increasing the strength of the ceramics. The properties of the resulting products are slightly lower than those of hot press sintering. The disadvantages of this method are similar to those of hot press sintering.

Packing

Silicon nitride sheets use appropriate outer boxes and internal buffer materials, and some components are also vacuum-packed.