Informatics Publishing Limited

S. Harsha ¹, S. Mahalakshmi ¹, Alexander George ²

Affiliations
1 Central Manufacturing Technology Institute, Bengaluru, IN
2 Karunya Institute of Technology and Sciences, Coimbatore, IN

Abstract

In the wire bonding process, the ever increasing gold (Au) price has created a necessity for looking at alternate materials viz., copper (Cu) for wire bonding, allowing Cu wire bonding to make a dramatic progress in recent years. The trend to shift towards Cu wire is expected to advance further in future, thus further improvement of bonding technique is indispensable as there are many challenges viz., handling of fragile pad structure, peeling, cracking below the bond pad, high oxidation rate, hardness and lower bondability of the wire bonds. In this paper, a series of experiments and characterizations (Mechanical, Electrical & SEM (Scanning Electron Microscope) has been conducted with 1mil Au and Cu wires to experimentally prove that Cu is a reliable replacement for Au in wire bonding process.

Keywords

Gold, Copper Ball and Wedge Bonds, Bond Parameters and Characterization.

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Hemant Kumar Singh ¹, Balaji Subramanian ¹, N. Kusuma ², S. Harsha ²

Affiliations
1 Indian Institute of Technology (IIT), Tirupati, IN
2 Central Manufacturing Technology Institute, Bengaluru, IN

Abstract

MEMS offers the uses of the membrane in various applications such as pressure sensors and micro-pumps. The working principle of all these devices is based on the deflection of the membrane due to the application of force. Piezoresistive pressure sensors are simpler to integrate with electronics, and they are inherently more linear than capacitive pressure sensors. The parameter optimization of the membrane is the prime challenge for achieving the best performance of the device. In this paper, the parametric optimization is incorporated for aspect ratio in terms of excellent sensitivity and linearity with the help of the design of experiments (DOE) and ANSYS. It is observed that the aspect ratio of 0.04 gives the maximum deformation with the elastic behaviour, among other sample points of the design.

Keywords

MEMS, Piezoresistive, Sensitivity, Membrane, DOE.

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Prabhat Ranjan ¹, S. Harsha ¹, Megha Agrawal ¹

Affiliations
1 Central Manufacturing Technology Institute, Bangalore, IN

Abstract

This signal conditioning circuit design is a micro-power, three terminal electrochemical cell amplifier that uses less than 1-μA total supply current for battery-powered or energy-harvested sensor applications. Electrochemical cells necessitate constant bias, which requires the amplifier circuit to be powered continuously to eliminate sensor start-up and settling times. The design is assembled on a dotted board compatible with the development Kit platform to allow testing with an MSP430 ultra-low-power processor to utilize the launchpad processor analog to digital converters (ADCs) and liquid crystal display (LCD) for stand-alone operation. The whole design consideration is done after taking into consideration of three-terminal screen printed electrode that can have several applications as verified by experimentations and results. The design can be used for agricultural applications as a wide range of sensor current has been taken into design consideration. This needs simple modification based on sensitivity and response time of sensor.

Keywords

MSP430, Op-Amp, Screen Printed Electrode, Trans-Impedance Amplifier, Potentiostat, Current Source.

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M. K. Mayuresh ¹, S. Harsha ¹, S. Usha ¹

Affiliations
1 Central Manufacturing Technology Institute, Bengaluru, IN

Abstract

This article presents the development of thin-film temperature sensor with two different types of packaging techniques on silicon wafer. Platinum (Pt) thin film sensing element is designed and fabricated by MicroElectro-Mechanical Systems (MEMS) technology, based on photolithography, e-beam evaporation and liftoff techniques on silicon substrate for machine tools applications. SiO2 and Ti are used as insulation and adhesion layers respectively. The thickness of SiO2, Ti and Pt are in nanometers and coated using e-beam evaporation system. The electrical connections were established using Nickel (Ni) coated Copper (Cu) leads. Temperature sensor was extensively characterized using thermal cycling chamber and Fluke calibrator. We have observed 99.975% linearity and ± 0.50C accuracy for temperature range of -25 to 1800C. The temperature coefficient of resistance (TCR) or Alpha (α) was found to be 0.002335 / 0C after repetitive thermal cycling experiment. The sensor is packaged with two different techniques, epoxy packaging and stainless steel (SS) probe package. Two types of epoxies were used, one is electrically and thermally conductive and the other one is ceramic epoxy for isolation and protection. The response time of the sensor with epoxy packaging and SS packaging are 0.4 Sec and 3 Sec respectively. The response time of SS probe can be further reduced by using thin tubes.

Keywords

MEMS, Sensors, Temperature Sensor, Thin-Film, Platinum.

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