Life Predict and Simulation of the Copper Wire in Flexible Printed Circuit Board
Fatigue failure of the circuit board's research focuses on the influence to the circuit board of vibration of rigid circuit board type, distribution of Electronic Components on the board etc. And there is relatively little research to the flexible circuit board's fatigue life research. Local stress-strain method is used to predict the fatigue life. Simulate actual fatigue test load conditions to established finite element model of flexible printed circuit board. Perform fatigue analysis under the periodicity stress. Drawn fatigue life of copper wire in different loading conditions. There is guiding significance to the follow-up test.
Numerical Prediction of Solder Fatigue Life in a High Power IGBT Module Using Ribbon Bonding
This study focused on predicting the fatigue life of an insulated gate bipolar transistor (IGBT) power module for electric locomotives. The effects of different wiring technologies, including aluminum wires, copper wires, aluminum ribbons, and copper ribbons, on solder fatigue life were investigated to meet the high power requirement of the IGBT module. The module’s temperature distribution and solder fatigue behavior were investigated through coupled electro-thermo-mechanical analysis based on the finite element method. The ribbons attained a chip junction temperature that was 30° C lower than that attained with conventional round wires. The ribbons also exhibited a lower plastic strain in comparison with the wires. However, the difference in plastic strain and junction temperature among the different ribbon materials was relatively small. The ribbons also exhibited different crack propagation behaviors relative to the wires. For the wires, the cracks initiated at the outmost edge of the solder, whereas for the ribbons, the cracks grew in the solder layer beneath the ribbons. Comparison of fatigue failure areas indicated that ribbon bonding technology could substantially enhance the fatigue life of IGBT modules and be a potential candidate for high power modules.
Effects of signaling topic structure on text recall
Two experiments studied effects of signaling devices (headings, overviews, and summaries) on text memory. In Experiment 1, subjects read a text with or without signals, then recalled the topics of the text. Signaling produced better memory for the topics and their organization. In Experiment 2, subjects recalled the content of the text they read, and recalls were scored for the number of accurately recalled ideas. Signals produced recalls that were better organized by text topics. Signals also influenced the distribution of recall of ideas: Subjects remembered more topics but recalled less about each accessed topic if the text they read contained signals than if it did not