# Reliability Prediction of Mixed-Signal Module Based on Multi-Stress Field Failure Mechanisms
## 5 Electro-Thermo-Mechanical Multi-Physics Coupling Analysis  
### D Model Construction of the Communication Module  
To determine the coupled stresses under different failure modes, this article adopts an electro-thermo-mechanical multi-physics coupling model, overcoming the limitations of  
Figure 11: Schematic diagram of the communication module simulation model.  
Figure 12: Communication module simulation test results showing transmit/receive timing strings.  
traditional single-stress superposition analysis. This model establishes a positive feedback loop to analyze the impact of electrical stress on the temperature rise, which subsequently induces thermal deformation and stress concentration. These variations may further lead to the loss of control over electrical stress within the module, ultimately negatively affecting its lifespan. By accurately capturing the amplification effects of stress interactions, this model avoids the underestimation of failure risks under extreme conditions commonly found in traditional static models, making it more suitable for scenarios involving transient power fluctuations in aerospace applications.  
Initially, a 3D model of the communication module is established using a cross-scale modeling method, integrating the microscopic thermal distribution of individual components with the board-level thermal distribution. This article primarily focuses on FPGA and SRAM, which generate relatively high heat and have numerous solder joints, for detailed microscopic structural modeling. For computational efficiency, the microscopic structures of other components are not included in the model.  
The 3D models of FPGA and SRAM are constructed based on their packaging types: the FPGA is packaged in FBGA-256, and the SRAM is packaged in TSOP-44. Figure 13 illustrates the package structures, with internal structures comprising the essential packaging components, bonding wires, die, die attach, and die pad.  
When constructing the 3D models for FPGA and SRAM, to reduce computational complexity, the bond wires, die attach, and the communication module structure are simplified. Additionally, the 3D model of the FPGA solder joints is simplified to a truncated spherical shape. The final 3D model is shown in Figure 14.  
Figure 14: Three-dimensional model of the communication module.  
Figure 13: Schematic diagram of internal structures. (a) FBGA-256 Solder Ball Chip Package; (b) TSOP-44 Pin Chip Package.  
The bonding wire in a semiconductor package plays a crucial role in providing electrical connections between the integrated circuit chip and the external pins or leads. It is typically made from gold, copper, or aluminum and serves as the pathway for electrical signals to and from the IC. In the context of the FPGA and SRAM 3D models, the bonding wire ensures that electrical signals can be properly transmitted between the chip and the external components, contributing to the overall functionality of the communication module. Although it is simplified in the 3D model to reduce complexity, in reality, the bonding wire ensures the reliable operation of the device by maintaining stable electrical connections.