Simulation Study on Thermal Characteristics and Thermal Stress of Semiconductor Laser Package

In semiconductor lasers, chip heat dissipation is a hot topic in current research. The increase in chip temperature will not only affect the service life of the laser, but also the thermal stress will reduce the reliability of the laser. To solve this problem, this research starts with the bonding layer between the laser chip and the substrate, uses nano-silver solder paste with high thermal conductivity as the bonding material, and uses the finite element analysis method to simulate the heat dissipation and stress distribution of the semiconductor laser at room temperature. At the same time, under the different heat consumption of the laser chip, the heat dissipation performance of the nano-silver solder and the commonly used AuSn and In solders was compared. The results show that the use of nano-silver solder paste is more conducive to the heat dissipation of the laser chip, and can effectively reduce the thermal stress of the laser chip. The research method proposed in this paper illustrates the feasibility of using nano-silver solder paste as the bonding material between the laser chip and the heat sink, and provides a reference for the design of semiconductor laser packaging.

I. Introduction

With the advancement of technology, semiconductor lasers have been widely used in industries such as industry, medicine, aerospace, measurement and inspection. Therefore, higher requirements are placed on the reliability of semiconductor lasers. The electro-optical conversion efficiency of a semiconductor laser is about 70%[1], and excess heat will be generated during working. This will increase the temperature of the laser chip. Increasing the temperature of the laser will cause the center wavelength of the output spectrum to be red-shifted, the threshold current to increase, the slope efficiency and output power to decrease, the mode to be unstable, the active region structure to generate non-uniform thermal stress, and the device life to be reduced. The semiconductor laser is composed of different materials. The mechanical and thermal performance mismatch between different materials will cause a series of reliability problems such as warpage and deformation of the laser chip and cracking of the adhesive layer when the chip temperature increases.