F. Stam - Academia.edu (original) (raw)
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This paper describes the evaluation of chip-toboard interconnection for low I/O sensor attachment... more This paper describes the evaluation of chip-toboard interconnection for low I/O sensor attachment. In particular the interconnections of different chip and printed circuit board (PCB) pad size ratios with offsets were investigated. Initial assemblies were made using lead-free, 99.3Sn0.7Cu solder. Solder joint shape prediction software, "surface evolver", has been used to simulate the solder joint shape formation for different ratio chip-to-board bond pad areas with different offsets between the two surfaces during the interconnection. The preliminary results show that depending on the solder volume and the aspect ratio of the chip-to-board pads, a convex or concave curvature of the solder joint is observed. Further simulation suggests the pad size plays a major role in the shape of the considered joints. 500 m pad 500 m pad Passivation layer 500 nm Sub pad finish Gold 0.2 m Chip pad finish Gold 200nm Chip pad finish Gold 200nm Sub pad finish Gold 0.2 m 300 m pad 500 m pad Passivation layer 500 nm PCB 0.25mm silicon Silicon dioxide Chromium 50nm Gold 200nm Pad Substrate Copper 64.8 m Nickel 5 m Gold 0.2 m 100 m pad 500 m pad Passivation layer 500 nm
ABSTRACT Cardiovascular disease affects millions of patients every year worldwide. Electroactive ... more ABSTRACT Cardiovascular disease affects millions of patients every year worldwide. Electroactive hydrogel polymers have the ability to swell or shrink in a fluid environment, which makes them an ideal candidate for preventing blood flow through blood vessels. The authors present preliminary reliability testing results of the long-term use of implanted EAP hydrogel material for intravascular applications. Mechanical testing was performed to determine the Young’s modulus and the pressure threshold to cause failure of the material in DI and Krebs solution. Accelerated testing was performed at elevated temperatures to determine the mean-time-to-failure using an Arrhenius model. The affects of various sized proteins on the EAP hydrogel were also investigated with and without electrical bias. An artificial circulation setup with mock blood vessels was used to determine the optimal dimensions of the EAP hydrogel material to prevent blood flow and the required minimum pressure to cause failure. The outcome of this study enables researchers to design EAP hydrogels with greater reliability and optimal shapes.
…, 2009
Technological developments in biomedical microsystems are opening up new opportunities to improve... more Technological developments in biomedical microsystems are opening up new opportunities to improve healthcare procedures. Swallowable diagnostic capsules are an example of this. In this paper, a diagnostic capsule technology is described based on direct-access sensing of the Gastro Intestinal (GI) fluids throughout the GI tract.
2011 International Reliability Physics Symposium, 2011
in biomedical microsystems are opening up new opportunities to improve healthcare procedures. Swa... more in biomedical microsystems are opening up new opportunities to improve healthcare procedures. Swallowable diagnostic sensing capsules are an example of this. In this paper, a novel direct access sensor (DAS) has been demonstrated which uses Flip Chip (FC) technology to expose the sensor to the liquid medium. An electrochemical study showed that the Anisotropic Conductive Adhesive (ACA) joint provides good connection and does not impair the sensor functionality. The reliability test results showed that most of the samples survived the humidity aging test and that only 2 out of 9 ACA connections of the same electrode failed. For the failed samples, the failure analysis showed that the tensile stress at the chip/epoxy interface caused a delamination at this interface.
This paper describes the evaluation of chip-toboard interconnection for low I/O sensor attachment... more This paper describes the evaluation of chip-toboard interconnection for low I/O sensor attachment. In particular the interconnections of different chip and printed circuit board (PCB) pad size ratios with offsets were investigated. Initial assemblies were made using lead-free, 99.3Sn0.7Cu solder. Solder joint shape prediction software, "surface evolver", has been used to simulate the solder joint shape formation for different ratio chip-to-board bond pad areas with different offsets between the two surfaces during the interconnection. The preliminary results show that depending on the solder volume and the aspect ratio of the chip-to-board pads, a convex or concave curvature of the solder joint is observed. Further simulation suggests the pad size plays a major role in the shape of the considered joints. 500 m pad 500 m pad Passivation layer 500 nm Sub pad finish Gold 0.2 m Chip pad finish Gold 200nm Chip pad finish Gold 200nm Sub pad finish Gold 0.2 m 300 m pad 500 m pad Passivation layer 500 nm PCB 0.25mm silicon Silicon dioxide Chromium 50nm Gold 200nm Pad Substrate Copper 64.8 m Nickel 5 m Gold 0.2 m 100 m pad 500 m pad Passivation layer 500 nm
ABSTRACT Cardiovascular disease affects millions of patients every year worldwide. Electroactive ... more ABSTRACT Cardiovascular disease affects millions of patients every year worldwide. Electroactive hydrogel polymers have the ability to swell or shrink in a fluid environment, which makes them an ideal candidate for preventing blood flow through blood vessels. The authors present preliminary reliability testing results of the long-term use of implanted EAP hydrogel material for intravascular applications. Mechanical testing was performed to determine the Young’s modulus and the pressure threshold to cause failure of the material in DI and Krebs solution. Accelerated testing was performed at elevated temperatures to determine the mean-time-to-failure using an Arrhenius model. The affects of various sized proteins on the EAP hydrogel were also investigated with and without electrical bias. An artificial circulation setup with mock blood vessels was used to determine the optimal dimensions of the EAP hydrogel material to prevent blood flow and the required minimum pressure to cause failure. The outcome of this study enables researchers to design EAP hydrogels with greater reliability and optimal shapes.
…, 2009
Technological developments in biomedical microsystems are opening up new opportunities to improve... more Technological developments in biomedical microsystems are opening up new opportunities to improve healthcare procedures. Swallowable diagnostic capsules are an example of this. In this paper, a diagnostic capsule technology is described based on direct-access sensing of the Gastro Intestinal (GI) fluids throughout the GI tract.
2011 International Reliability Physics Symposium, 2011
in biomedical microsystems are opening up new opportunities to improve healthcare procedures. Swa... more in biomedical microsystems are opening up new opportunities to improve healthcare procedures. Swallowable diagnostic sensing capsules are an example of this. In this paper, a novel direct access sensor (DAS) has been demonstrated which uses Flip Chip (FC) technology to expose the sensor to the liquid medium. An electrochemical study showed that the Anisotropic Conductive Adhesive (ACA) joint provides good connection and does not impair the sensor functionality. The reliability test results showed that most of the samples survived the humidity aging test and that only 2 out of 9 ACA connections of the same electrode failed. For the failed samples, the failure analysis showed that the tensile stress at the chip/epoxy interface caused a delamination at this interface.