HTCC circuit silver paste, silver palladium paste, gold conductor paste

High temperature co fired ceramic HTCC silver paste（High Temperature co-fired Ceramic）， Using materials such as tungsten, molybdenum, molybdenum, manganese and other high melting point metal heating resistor slurries, they are printed on 92-96% alumina cast ceramic green bodies according to the requirements of heating circuit design. 4-8% sintering aids are then stacked in multiple layers and co fired into one at high temperatures of 1500-1600 ℃.

Due to the high firing temperature of HTCC, it uses refractory metal materials such as tungsten, molybdenum, manganese, etc. These materials have low conductivity and can cause defects such as signal delay, making them unsuitable for use as substrates for high-speed or high-frequency micro assembly circuits. However, HTCC substrates have the advantages of high structural strength, high thermal conductivity, good chemical stability, and high wiring density, making them widely applicable in high-power micro assembly circuits.

The most important high-temperature co fired ceramics are those mainly composed of alumina, mullite, and aluminum nitride.

Aluminum oxide silver paste

Alumina ceramic technology is a relatively mature microelectronic packaging technology, which is made of 92-96% alumina and 4-8% sintering aids sintered at 1500-1700 ℃. Its wire materials are refractory metals such as tungsten, molybdenum, molybdenum manganese, etc.

The substrate technology is mature, the cost of dielectric materials is low, and the thermal conductivity and bending strength are high. However, aluminum oxide multilayer ceramic substrates have the following drawbacks:

(1) The high dielectric constant affects the improvement of signal transmission speed;

(2) The high resistivity of the conductor results in significant signal transmission losses;

(3) The thermal expansion coefficient is significantly different from that of silicon, which limits its application in supercomputers.

mullite

The dielectric constant of mullite is 7.3-7.5, while the dielectric constant of alumina (96%) is 9.4, which is higher than mullite. Therefore, the signal transmission delay time of mullite can be about 17% smaller than that of alumina. Moreover, the thermal expansion coefficient of mullite is very close to that of silicon, so this substrate material has been rapidly developed.

For example, companies such as Hitachi and Shinko have developed mullite multilayer ceramic substrates, and their products have good performance indicators. However, the wiring conductors of this substrate can only use tungsten, nickel, molybdenum, etc., which have high electrical resistivity and lower thermal conductivity than aluminum oxide substrates.

Aluminum nitride silver paste

For aluminum nitride substrates, due to their high thermal conductivity and thermal expansion coefficient matching semiconductor materials such as Si, SiC, and GaAs, their dielectric constant and dielectric loss are superior to aluminum oxide. Additionally, AlN is a relatively hard ceramic that can still work well under harsh environmental conditions.

For example, AlN ceramics still have excellent stability at high temperatures. Therefore, aluminum nitride has been widely studied and has made remarkable progress as a multi-layer substrate material both domestically and internationally.