Osaka university and denso announced on March 28, 2016, in Japan's new energy and industrial technology development organization (NEDO) under the project, is expected to increase power semiconductor silicon carbide (SiC) were found bonding material self-healing phenomenon of long-term reliability. The researchers found that under the high temperature equipment working environment, used as a bonding material of silver sintering material to repair the cracks, which greatly improves the SiC semiconductor application possibility in the field of car and so on.
The SiC adhesive joint using silver paste sintering method, the method using the mixture of micron and submicron silver paste, 30 minutes at 250 ¡æ low temperature in air environment to implement joint craft, obtained the bare chip bonding structure. With the use of common nanoparticles under pressure than joint method has many advantages, including easy operation; Raw material is cheap; Strength higher than that of welding, to over 40 mpa; For more than five times as much as welding, the thermal conductivity of 150 w/mK above; Can be realized without pressure treatment or 1 mpa under low pressure.
The high density sintered silver particles was prepared in the experiment of the tensile test, tensile load is applied to form the crack. Then, considering the working temperature of SiC power semiconductor kept the test piece in air environment in the temperature of 200 ~ 300 ¡æ, the change of the crack front is studied, and the change of tensile strength. Results show that under the 200 ¡æ after 50 hours, crack closure gradually, begin to repair themselves, and, under the 300 ¡æ after 10 hours later, the cracks appeared a wider range of closed, self-healing phenomenon becomes more obvious. In addition, after 100 hours, the tensile strength back to test pieces of the same level with no crack.
Application in power converter power semiconductor products, the main reason for the failure is the strip joints. Previously in NEDO "low-carbon society of a new generation of power electronic project" (2009 ~ 2019), the research and development of electrical and thermal properties are welding material excellent silver sintering material than in the past, but in practical stripping of the question of short life. The discovery of the found by the possibility of repair to solve the problem of stripping life.
