NDLI: Fluxless packaging of an implantable medical device for transcorneal electrical stimulation

Content Provider	IEEE Xplore Digital Library
Author	Le, Fuliang Lo, Jeffery C. C. Qiu, Xing Lee, S. W. Ricky Li, Xing Tsui, Chi-Ying Ki, Wing-Hung
Copyright Year	2015
Description	Author affiliation: Department of Mechanical and Aerospace Engineering, Center for Advanced Microsystems Packaging (Le, Fuliang; Lo, Jeffery C. C.; Qiu, Xing; Lee, S. W. Ricky) \|\| Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (Li, Xing; Tsui, Chi-Ying; Ki, Wing-Hung)
Abstract	Transcorneal electrical stimulation (TcES) is one of the potential therapies to prevent retinal degeneration. This study reports on an implantable medical device for TcES. The regular TcES components, such as stimulator chips, metal wires, electrodes and printed circuit boards (PCBs), are all packaged into the device. The device has a thin-film shape and is soft enough to bend, thus it is placed beneath the cornea without exposure to the outside. The stimulator chip, with the function of generating precise stimulation current to prevent retinal degeneration, is flip bonded onto a flexible PCB using gold studs and thermosonic bonding process. Thermosonic bonding eliminates the use of flux, which is not biocompatible with in-vivo implants. The surfaces of the gold stud bumps are in general non-uniform. Coining is an essential pretreatment of compressing the gold stud bumps against a flat solid surface to obtain much smoother & larger surfaces. This pretreatment helps form high-strength joints between the gold stud bumps and the PCB pads. In the packaging process, underfill is applied in the gaps between the chips and the flexible PCB to enhance the reliability of the gold joints. A compression molding step is subsequently conducted to cover all internal components with a silicone material. The two electrodes, which are made of gold studs, can be exposed by grinding. A coining step is followed to ensure the flatness of the two electrodes.
Starting Page	1
Ending Page	5
File Size	1374177
Page Count	5
File Format	PDF
e-ISBN	9781467372695
DOI	10.1109/EPTC.2015.7412282
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2015-12-02
Publisher Place	Singapore
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Gold Electrodes Electrical stimulation Bonding Retina Wires Surface treatment
Content Type	Text
Resource Type	Article

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

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