Replace of vias with polymer thick film pastes (PTF) for the use on flexible substrates

The use of flexible flat cables (FFC) and flexible printed circuits (FPC) constantly increases in the next years. The development of competitive products can be improved on basis of these technologies. The advantages within the range reliability and costs could be used however only with the consideration of a complete view of the entire process chain efficiently and trend-setting. We made some investigations for simple replace of vias with two different and simple solutions for the use on flexible printed circuits. The goal is a simple, cheap und reliable technology on single-sided base materials. We select polyimide base material for the start of our investigations. We use the polymer thick film technology and the component placement of Resistors with 0 Ω for the crossing of the first layer. We manufactured some boards and use temperature storage and humidity tests for acceleration. During the tests we measure the change of resistance in the 3 different types of our test samples and characterize the technologies with the help of destructive and non-destructive tests. Especially the polymer thick film technology is a simple and fast method for solutions with flexible printed circuits. We describe our complete methods for manufacturing of the different sample types, the test methods and discuss our final view to the results. The complete verification and validating of the different methods we investigate in the last weeks and will be closed during February and March 2008. A lot of the main influences and factors for decisions on design and manufacturing we discussed during our examinations with test vehicles.