TY - JOUR
T1 - Flexible chip-scale package and interconnect for implantable MEMS movable microelectrodes for the brain
AU - Jackson, Nathan
AU - Muthuswamy, Jitendran
N1 - Funding Information:
Manuscript received October 21, 2008; revised December 31, 2008. First published February 10, 2009; current version published April 1, 2009. This work was supported in part by NIH Grants R21NS051773 and R01NS055312 and in part by the Arizona Biomedical Research Commission. Subject Editor K. Najafi.
PY - 2009
Y1 - 2009
N2 - We report here a novel approach called microelectromechanical systems (MEMS) microflex interconnect (MMFI) technology for packaging a new generation of Bio-MEMS devices that involve movable microelectrodes implanted in brain tissue. MMFI addresses the need for the following: 1) operating space for movable parts and 2) flexible interconnects for mechanical isolation. We fabricated a thin polyimide substrate with embedded bond pads, vias, and conducting traces for the interconnect with a backside dry etch, so that the flexible substrate can act as a thin-film cap for the MEMS package. A double-gold-stud-bump rivet-bonding mechanism was used to form electrical connections to the chip and also to provide a spacing of approximately 15-20 μm for the movable parts. The MMFI approach achieved a chip-scale package that is lightweight and biocompatible and has flexible interconnects and no underfill. Reliability tests demonstrated minimal increases of 0.35, 0.23, and 0.15 mΩ in mean contact resistances under high humidity, thermal cycling, and thermal shock conditions, respectively. High-temperature tests resulted in increases of <90 and ∼4.2 mΩ in resistance when aluminum and gold bond pads were used, respectively. The mean time to failure was estimated to be at least one year under physiological conditions. We conclude that MMFI technology is a feasible and reliable approach for packaging and interconnecting Bio-MEMS devices.
AB - We report here a novel approach called microelectromechanical systems (MEMS) microflex interconnect (MMFI) technology for packaging a new generation of Bio-MEMS devices that involve movable microelectrodes implanted in brain tissue. MMFI addresses the need for the following: 1) operating space for movable parts and 2) flexible interconnects for mechanical isolation. We fabricated a thin polyimide substrate with embedded bond pads, vias, and conducting traces for the interconnect with a backside dry etch, so that the flexible substrate can act as a thin-film cap for the MEMS package. A double-gold-stud-bump rivet-bonding mechanism was used to form electrical connections to the chip and also to provide a spacing of approximately 15-20 μm for the movable parts. The MMFI approach achieved a chip-scale package that is lightweight and biocompatible and has flexible interconnects and no underfill. Reliability tests demonstrated minimal increases of 0.35, 0.23, and 0.15 mΩ in mean contact resistances under high humidity, thermal cycling, and thermal shock conditions, respectively. High-temperature tests resulted in increases of <90 and ∼4.2 mΩ in resistance when aluminum and gold bond pads were used, respectively. The mean time to failure was estimated to be at least one year under physiological conditions. We conclude that MMFI technology is a feasible and reliable approach for packaging and interconnecting Bio-MEMS devices.
KW - Bio-microelectromechanical systems (MEMS)
KW - Biomedical microdevices
KW - Brain implants
KW - Microflex technology
KW - Neural prostheses
KW - Polyimide
UR - http://www.scopus.com/inward/record.url?scp=67349098839&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=67349098839&partnerID=8YFLogxK
U2 - 10.1109/JMEMS.2009.2013391
DO - 10.1109/JMEMS.2009.2013391
M3 - Article
AN - SCOPUS:67349098839
SN - 1057-7157
VL - 18
SP - 396
EP - 404
JO - Journal of Microelectromechanical Systems
JF - Journal of Microelectromechanical Systems
IS - 2
ER -