Dynamic Response Determination of Electronic Printed Circuit Board (PCB)

摘要

The automotive electronic systems are composed of two major mechanical elements: an equipment housing or enclosure, and a printed circuit board (PCB) assembly. The PCB is made up of alternating layers of copper and FR-4 glass epoxy laminated together. An estimation of the mechanical reliability of a PCB in an electronic system is considered to be an important part of the overall reliability estimate of the entire system and vibration is often one of the key causes of system and component failures. As different kind of electronic components (like transformers, capacitors, chips etc) are mounted on both sides of the PCB using solder joints, adhesive etc, various complexities are encountered while modeling them for analysis. For avoiding those, simple PCBs without any components are considered for the present study. This paper focuses on the methodology to understand and predict the dynamic behavior of the system using various mechanical tests and simulations. The material properties (elastic modulus and Poisson's ratio) of the PCB are obtained from standard tensile testing based on ASTM D638. The modal response of the model, including modal frequencies and mode shapes, is acquired through testing. Next, the same model is also analyzed by finite-element simulations to determine the same dynamic properties. Thus, the results obtained through both approaches are compared in detail. Further, with an effort to understand the force response behavior of the system, a swept sine vibration test is carried out on the same model using specified vibration level as an input excitation and results in, response amplitude curves at specified locations. This same scenario is simulated with finite element analysis using commercial available software, assuming different damping ratios. These simulation results are compared with the test results for deducing the appropriate damping ratio which is one of the very important factors for dynamic analysis.