# Reliability Prediction of Mixed-Signal Module Based on Multi-Stress Field Failure Mechanisms
## 3 Failure Modes and Mechanism Identification of Key Components in the Communication Module  
### Analysis of Communication Module Operation and Key Component Classification  
This article takes a specific communication module as an example to conduct a weakness analysis of its key components and identify their main failure mechanisms. The circuit structure of the communication module is shown in Figure 2, which primarily includes FPGA, SRAM, DS26C31, DS26C32, and a crystal oscillator. The communication module operates with the FPGA as its core, coordinating the submodules and processing signals to achieve system functionality. The SRAM stores received command data and telemetry data during the operation. The DS26C31 and DS26C32 convert between single-ended and differential signals, enabling asynchronous serial communication among the FPGA, the management unit, and other functional modules via the RS422 protocol. The main operational process of the communication module is outlined in Figure 3. First, the module receives command data from the management unit via RS422. The FPGA then decodes the command and stores the processed data in SRAM. Subsequently, the FPGA retrieves telemetry data from SRAM, assembles the data frame, and transmits it to the management unit via RS422. Afterward, the FPGA reads the stored command data from SRAM and forwards it to other functional modules through RS422. Finally, the FPGA collects the telemetry data returned by the functional modules, stores it in SRAM, and transmits it to the management unit upon receiving the next command. By considering the operational conditions of the spacecraft in orbit, a preliminary analysis of the failure modes and their impact on the key components within the communication module can be conducted. The results are summarized in Table 1. This article primarily focuses on the effects of three coupled factors--electrical, thermal, and mechanical stress--on the reliability of electronic components. It is considered that the shell and shielding layer of the spacecraft can achieve better protection against radiation and other stresses, and strict screening during the manufacturing process ensures that there are no manufacturing defects. Figure 2: Schematic diagram of the communication module circuit. The crystal oscillators, DS26C31, and DS26C32 are aerospace-grade components that meet the screening criteria and provide outstanding stability under harsh environmental conditions. The stability of crystal oscillators arises from their material characteristics, whereas DS26C31 and DS26C32 employ differential transmission, power isolation, and built-in hysteresis comparators that can adapt to varying signal levels, preventing misjudgment caused by threshold fluctuations. These features collectively enable them to maintain high reliability even when exposed to complex electromagnetic environments, temperature fluctuations, and mechanical stress, resulting in significantly lower failure rates compared to ordinary electronic components [18]. [PERSON] et al. [19] also confirmed the long-term reliability of mixed-signal interface circuits for aerospace applications, showing that under combined thermal and mechanical stress, the failure rate stays below 0.1% over 20 years; thus, they pose minimal reliability concerns. Consequently, this article does not analyze these components further. Although resistors, capacitors, and diodes are also part of the module, they do not appear in the circuit diagram. Thick-film resistors and capacitors experience only limited parameter drift under low electrical stress [20; 21; 22], and capacitors mainly serve as filters rather than playing a critical role in system functions. Even though resistor parameter drift may affect the amplitude of RS422 signals, this does not compromise the communication module's normal operation. Diodes primarily act as protection elements, and aerospace-grade diodes that have obtained relevant certifications demonstrate negligible failure rates in protection circuits [23; 24].