Thin film flexible circuits with embedded ASICs–Enabling technology for sophisticated medical applications

The requirements for thin film substrates have increased over the last years, as new materials, ongoing miniaturization and higher connectivity and complexity of circuit designs are arising. Especially the medical field, with its various application areas, drives the development of new technologies and new material combinations. Specifically, components for catheter or endoscope equipment are often difficult to realize, as limited space/cross section compete with the demand for higher functionality in the tip, and thus, requiring a higher number of connections to be routed out. One possibility to overcome this problem, is a local digitalization of the signals of the various sensors in the tip and doing a serial data transmission to the outside, reducing the required number of leads. To maintain a very small form factor, we have developed a technology that allows the direct integration of thinned ASIC chips into thin film flexible circuits. An example application, for the readout of catheter shape and positioning, was realized. Our contribution will give an overview of the target application and describe the integration technology for the thinned dies together with the build-up of the thin film flexible circuits.