Encapsulation utilizing a thin parylene-C
This paper presents an embedded chip integra- tion technology that incorporates silicon housings and ﬂexible Parylene-based microelectromechanical systems (MEMS) devices. Accelerated-lifetime soak testing is performed in saline at elevated temperatures to study the packaging performance of Parylene C thin ﬁlms. Experimental results show that the silicon chip under test is well protected by Parylene, and the lifetime of Parylene- coated metal at body temperature (37 ◦C) is more than 60 years, indicating that Parylene C is an excellent structural and packaging material for biomedical applications. To demonstrate the proposed packaging technology, a ﬂexible MEMS radio-frequency (RF) coil has been integrated with an RF identiﬁcation (RFID) circuit die. The coil has an inductance of 16 μH with two layers of metal completely encapsulated in Parylene C, which is microfabricated using a Parylene–metal–Parylene thin-ﬁlm technology. The chip is a commercially available read-only RFID chip with a typical operating frequency of 125 kHz. The functionality of the embed- ded chip has been tested using an RFID reader module in both air and saline, demonstrating successful power and data transmission through the MEMS coil.
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