Hybrid Integration; Case Study with Sun Sensor for Cube Satellites

Abstract

An innovative electronic system assembly approach, i.e. hybrid integration combining printed electronic components with/on Flexible Circuit Boards (FCBs) equipped with conventional Surface-Mounted components (SMDs) was implemented in order to realize a sun sensor. Technology-wise, a clear benefit was achieved from the combination of the advantages of both large area printed electronics based on printing processes (e.g. flexibility, light weight, cost effectiveness, etc.) and SMDs with high-end functionalities and robustness. Printed electronics uses additive deposition methods similar to conventional press printing -- such as inkjet printing, screen printing, gravure printing, etc. -- applying a stack of layers on flexible substrates. By depositing electrically active layers (e.g. conductors, semiconductors and insulators), basic electronic building blocks such as resistors, capacitors, thin film transistors, etc. can be made. On the other hand, FCBs are commonly used where flexibility, space savings, or production constraints limit the use of rigid PCBs. Typically, conventional photolithography and standard SMD integration are combined to realize FCBs. A hybrid sun sensor was demonstrated within the Swiss Space Office funded project hybSat (2014--2016), by HIGHTEC and CSEM. The developed sun sensor comprises inkjet printed organic photodiodes (OPDs), printed resistors, printed capacitors, high-end SMDs and operational amplifiers on a FCB. The fabricated flexible sun sensor is suitable for cube satellites since it is extremely thin, light weight and cost effective. The exampled hybrid technology offers new possibilities to the system designers (towards smart PCBs), material providers (printable functional inks) and extends the current range of products (e.g. wearable, flexible electronics).