Evaluation of very low bending radius of flexible circuits beyond the standard design rules
The Flexible Printed Circuits (FPC) used in high-end applications have some specific characteristics. It has a more complex build-up and must be compatible with repair processes. Moreover, they are used in harsh environment and long mission profile. Current FPC design are based on industrial standards, which propose design rules, such as minimum bending radius calculated from the maximum accepted copper elongation. This work is part of a large study focused on the development of a new generation of digital board solutions for electronic interconnection. In this paper, a finite element simulation study will be applied to FPC bending analysis beyond industrial standard limits. As a conclusion, we propose to consider the maximum copper strain and the bending shape for the minimum bending radius definition.
Experimental and numerical analyses of flexible PCBs under various loading conditions
This work will present case studiesof three types of Flexible Printable Circuits subjected to different loading conditions in order to evaluate their tecnologies regarding mechanical reliability. Typical causes of failure in electronic devices are associated with mechanical stress, moisture, heat from transportation and field use. Typically manufacturers carry out tests to evaluate the reliability of electronic components regarding these environmental loads. Common tools used for this evaluation, in early stages of design, are FEA (Finite Element Analysis) and experimental laboratory tests. In this work simulation models were generated aiming at developing tools for early stages of design, and mechanical tests were performed to assess actual reliability of parts and also to provide information to evaluate the simulation models. The different types of failure in the flexible printed embeded circuits, such as delamination, will be presented. Failures due to high shear stresses in flex- rigid joints will also be evaluated. Experimental tests and computational simulation will also be applied in order to perform these evaluations.
Accurate measurements of output characteristics and detonations of motorbike high-speed racing engine and their optimization at actual atmospheric conditions and combusted mixture composition
Abstract At a motorbike high speed racing engine there is very important an output engine characteristics which depends significantly on a detonation combustion rate, atmospheric conditions and a combusted mixture composition. The combustion process has got a relevant influence on a wear degree of main engine parts or on their damage eventually. The detonation combustion rate is very important because this kind of burning can be not only destructive but a useful phenomenon, as well. If the process of detonation burning is kept on a certain level, it can help significantly to the next increasing of an engine power output. In this article there is described the measurements of output characteristics of a high-speed racing engine which were performed by means of a data-recording system and the detonation combustion was evaluated using a quantitative method. The actual values of atmospheric conditions and the mixture composition were added to the measured values. Then the obtained values are compared visually with a damage degree of an engine piston caused by the detonation burning. The result is a limit value expressed in a number of detonation units related to a run distance interval of the vehicle driven by the high-speed racing engine. In framework of this run distance interval there is the process of detonation burning profitable. As well as it increases an engine power output and together it is not destructive with regard to engine design parts.