Characterisation of embedded filters in advanced printed wiring boards

This paper describes the design, fabrication and test of a range of third o rder LC low pass Butterworth filters in MCM-L technology. There are seven f ilters in the range, each consisting of two inductors and one capacitor wit h cut-off frequencies ranging from 10 to 540 MHz. Inductance values range f rom 9.9 to 530 nH, and capacitance values vary from 14 to 723 pF. Air-core (by which we mean no magnetic material) spiral winding structures are desig ned to provide the inductive functions. A new FR4 type laminate material, w hich was developed by ISOLA, is used to form integrated parallel plate capa citor structures. The range of filters was successfully manufactured and el ectrically characterised using a HP4195A impedance analyser. Some environme ntal testing was also carried out on the embedded filters. These included t hermal shock and humidity testing. There were no obvious changes in device performance after the environmental tests. (C) 2001 Elsevier Science Ltd. A ll rights reserved.