Fault Monitoring And Early Warning Of Board Level Solder Joint Interconnection

Micro-assembly and high-density packaging technology has been widely used in electronic industry, leading the number of solder joints is large and the tiny size of them. The most important function of these solder joints, which between the chip and the external circuit, is to realize the electrical connections and provide the mechanical support. Their function may be simple, but the impact is crucial. Statistics showed that:one of the main causes of the malfunction of electronic equipment is the failure of some (or one) solder joint. On the other hand, with the development of reliability assurance technology for electronic equipment, traditional post-maintenance reliability assurance is gradually changing to Condition Based Maintenance. So that, it must realize the failure prediction of the key component in the whole system, such as interconnect solder joints.PHM (prognostics and health management) technology is used to assess product reliability in actual use environment, in order to achieve the goal of "Condition Based Maintenance" Nowadays, solder joint failure monitoring and early warning technology become an important part of the ePHM technology. The embedded measurement structures which with early warning capability, are used to perform real-time, in-situ monitoring the solder joints, and that become the research focus of microelectronics packaging and assembly reliability.Firstly, focusing on the creep failure of solder joints, the general degeneration process of solder joints, which usually exposed to a variety of load conditions, was discussed. And on this basis, a monitoring circuit for prognosing solder joint degradation, using resistive bridge measurement, has been presented. Then, in view of Electronic Product Reliability Engineering applications, a method, that apply the circuit to monitor and alarm the degradation of board-level interconnected solder joints, also has been presented. In the slow and rapid degradation stage of solder joints which on service, the embedded monitoring circuit has been set a reasonable starting and ending point for real-time monitoring and assessment on their health. When the electrical properties of solder joint degradation in the early stages, it could alert and record the data for the solder joint resistance which is used for remaining life prediction. It realizes the function of early warning of solder joint degradati and remaining life prediction. Because of the two issues:the low-frequency resistance measurement is not an effective way to monitor the signal distortion caused by the solder joint, as well as high frequency electrical signals is much more sensitive on the defects of the solder joints than the low-frequency signals, the presence of cracks in the solder joint on the impact of high frequency electrical properties was preliminary studied by the way of software simulation and experimentation. On this basis, a brief circuit design which with real-time, on-situ monitoring function was proposed.Finally, the signal integrity problems for solder joints of digital circuit was discussed, and a built-in test circuit of the solder joints of FPGAs was described using verilog HDL. The design suitable for reliability assessment of FPGAs’solder joints and meet the "on-site, real-time testing" requirement.