IGBT module mainly consists of several hybrid IGBT chips, and the electrical connections are realized through aluminum wires.In the standard IGBT encapsulation, a single IGBT will also have a continuation diode, followed by a large amount of silicon gel over the chip, and finally wrapped in a plastic shell, the IGBT unit stack structure as below.
It is made up of chips, DBC, and metal cooling plates (usually Copper) from top and down .DBC consists of three layers of material the upper and lower layers are metal layers, and the middle layer is insulating ceramic layer.DBC has a better performance than ceramic substrate: it has lighter weight, better thermal conductivity and better reliability.
In the usual power cycle or temperature cycle, the chip, the solder layer, the substrate, the bottom plate and the package shell will experience the temperature and temperature gradient of different layers.Coefficient of Thermal Expansion (CTE, Coefficient of Thermal Expansion) is an important performance index of the materials, refers to in a certain temperature range temperature rise per 1 degree, to the line size of the increase in the ratio of the length of zero degrees.
Blow structure is commonly used in thermal expansion coefficient.
Due to the different thermal expansion coefficients of each materials, thermal strain between the temperature changes of different material, mutual connection layer between the joint produces due to thermal stress fatigue wear and tear.Therefore, the thermal behavior of devices is closely related to the structure of module encapsulation.
Research shows that working temperature every 10 ℃, caused by a temperature failure rate doubled.
In IGBT module, there is NTC thermistor chip components to control the temperature.
Due to the thermal expansion coefficients material has a relative with temperature.
So NTC thermistor chip is a key of IGBT Module, the characteristic is high accuracy and high stability. And the size also can be 0.3*0.3mm.