A batch-mode assembly and packaging technology for 3-axis tri-fold inertial measurement units
This paper reports a batch-mode generic 3-D precision assembly and wafer-level packaging technology for 3-axis tri-fold inertial measurement units (IMUs) using silicon mounting jig wafers with embedded vacuum channels. This approach allows use of optimized single-axis IMUs without manufacturing and structural constraints of forming 3-axis in a chip, and improving the overall yield by testing the chips prior to 3-D assembly. The 3-D chip assembly is performed by a controlled sequence of vacuum through the channels and bottom access holes, ambient pressurization, and raise of temperature to form permanent rigid tri-fold bond to the jig wafer.
A tri-fold inertial measurement unit fabricated with a batch 3-D assembly process
This paper reports a tri-fold inertial measurement unit (IMU) that is fabricated with a batch-mode 3-D assembly process. Each chip of a tri-fold die includes a single axis z-gyroscope and 0-2 lateral-accelerometers. The tri-fold dies are batch-mounted on sidewalls of silicon cavities on a wafer to form 6-axis IMUs. The accelerometer has a measured bias instability of 6.8 μg and a noise floor of 66 μg/rt-Hz. The gyroscope has a measured bias instability of 29 °/hr and an angle random walk of 0.020 °/s/rt-Hz (1.2 °/rt-hr).
Low-cost data acquisition systems for photovoltaic system monitoring and usage statistics
This paper presents the design of a low-cost data acquisition system for monitoring a photovoltaic system’s electrical quantities, battery temperatures, and state of charge of the battery. The electrical quantities are the voltages and currents of the solar panels, the battery, and the system loads. The system uses an Atmega328p microcontroller to acquire data from the photovoltaic system’s charge controller. It also records individual load information using current sensing resistors along with a voltage amplification circuit and an analog to digital converter. The system is used in conjunction with a wall power data acquisition system for the recording of regional power outages. Both data acquisition systems record data in micro SD cards. The data has been successfully acquired from both systems and has been used to monitor the status of the PV system and the local power grid. As more data is gathered it can be used for the maintenance and improvement of the photovoltaic system through analysis of the photovoltaic system’s parameters and usage statistics.