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.
Vapour phase soldering on flexible printed circuit boards
The paper presents experimental results about Vapour Phase Soldering on flexible printed circuit boards, where the standard Surface Mounted Technology process was used for investigation. Test boards were prepared from FR4 type Printed Circuit Boards and single-sided flexible polyimide substrates. Lead-free SAC305 paste and different chip size surface mounted resistors were used for the test assembly. The soldering was performed with heat-level vapour phase method in a commercial oven. The tests were composed of different board setups: where the FR4 or the flexible boards were soldered without fixtures, and where the flexible boards were supported by fixtures. The results were evaluated with X-ray microscopy, cross-section optical inspection (IMC tests) and shear tests. The conclusion reveals similar quality factors in all cases, rendering vapour phase soldering a plausible alternative reflow method for soldering on flexible printed circuit boards
Generalized Hamilton's Principle and Variational Equation of Motion in Nonlinear Elasticity Theory, with Application to Plate Theory
A generalized Hamilton's principle and the associated variational equation of motion are presented for finite elastic deformations. By means of the generalized variational equation of motion, it is possible to deduce immediately the usual nonlinear equations of elasticity, such as were discussed by Novozhilov. The inconsistence Novozhilov's work for a simplified nonlinear case of technical importance is pointed out. In its linearized version, the generalized variational equation of motion is next employed in the derivation of plate equations for both flexural and extensional motions, which are finally compared with those given by previous authors.