Manufacturing of an In-Package Relative Humidity Sensor for Epoxy Molding Compound Packages
Romina Sattari (TU Delft - Electronic Components, Technology and Materials)
Henk van Zeijl (TU Delft - Electronic Components, Technology and Materials)
Guo Qi Zhang (TU Delft - Electronic Components, Technology and Materials)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
This study presents the design and fabrication of an in-package relative humidity sensor for epoxy molding compound (EMC) packages. The sensor comprises shielded interdigital electrodes (SIDE) for in-situ monitoring of humidity absorption/desorption in the package encapsulation layer. A novel approach is employed in the device fabrication to maximize the electrical field lines to pass through the EMC and enhance the sensitivity. The manufactured wafer includes 6×6mm2 dies, each containing six identical capacitive sensors with an area of 480 × 620 μ m2. SU-8 through polymer vias (TPVs) with high aspect ratio were created to locally mold the sensors by EMC. The linear capacitance change with the relative humidity level is simulated in COMSOL Multiphysics. Three designs were compared, and the calibration results show the capacitance value of 1.54 pF and 5.85 pF before and after molding, respectively. The capacitance value stays within the range of 5.85 to 5.86 pF with less than 7 aF variation under different biasing voltages, indicating the stability and robustness of the capacitance.