Aiming at the chip crack problem of K1-5 shell using No. 10 steel as the substrate, the eutectic stress was simulated, and the procedure was optimized. The results show that no matter how slow or fast heat dissipation is adopted, the thermal stress caused by the huge difference in thermal expansion coefficient between No. 10 steel and Si chip can not be fundamentally changed. By comparing three different shell materials, it can be seen that the thermal stress of the K1-5 shell with Kovar material as the matrix is the lowest, 316 MPa, while the No. 10 steel is the highest, 19 800 MPa, far beyond the limit breaking strength of silicon chip 544 MPa. According to the basic theory of stress, and comparing the difference between the thermal expansion coefficient of the three materials and Si chip, it is found that the difference in the thermal expansion coefficient of Kovar and Si chip is the smallest, followed by oxygen-free copper, and No. 10 steel is the largest, which is the fundamental reason for chip cracking when sintering K1-5 shell with No. 10 steel as the matrix. From simulation analysis and practical experiments, it has been proved that replacing the shell with Kovar material can effectively solve the problem of chip cracking.