The Effect Of The Adhesive Void In Packaging Structure On The Thermal Drift Of Micro-Accelerometer

The comb micro-accelerometer is widely applied in the fields such as entertainment, national defense, etc. It is also one of the important research objects in the micro sensors. However, the output thermal drift of micro-accelerometer due to the temperature variation of the ambient environment significantly reduces the measurement accuracy. The void in the adhesive will affect the packaging structure as the temperature varies and result in the output thermal drift. The influence of adhesive void on the output thermal drift should be concerned to improve the precision of the micro-accelerometer. In recent years, the studies on adhesive void mainly analyze the influence of void on the thermal aspects of packaging structure, and there is little research about the influence of void on the structure deformation or output thermal drift in micro-accelerometer. Therefore, it is necessary to analyze the effect of the void in adhesive layer on the output thermal drift to improve the accuracy of micro-accelerometer.In this article, the influence of adhesive void on micro-accelerometer output thermal drift is decomposed into two parts. Firstly, the influence of adhesive void on the packaging structure deformation is analyzed. Secondly, the influence of packaging structure deformation on micro-accelerometer output thermal drift is analyzed. The main contents are as follows:1. The influence of adhesive void on the packaging structure is analyzed by the theory and simulation calculations. The packaging structure model in simulation is built via ANSYS finite element software, in which the adhesive void are set up by ‘birth and death’ technology. A structural analysis approach is adopted in the theory calculation, and the standard method for solving differential equations is used to derive the analytical conclusion. The comparison of the interfacial shear stresses solved by theory and simulation calculations indicates that the deformation of the packaging structures with and without the adhesive void after cooling can be accurately calculated by the simulation model.2. The influence of the packaging structure deformation on micro-accelerometer output thermal drift is analyzed by theory and simulation calculations. The movement of the anchors after cooling is used to calculate the output thermal drift. The comparison of the thermal drifts calculated by theory calculations and simulation indicates that both the two methods could use the movement of anchors to calculate the micro-accelerometer output thermal drift. Meanwhile, the influence of the anchor movement in the insensitive direction on the output thermal drift is negligible.3. Based on the previous analyses, the influence of adhesive void on the micro-accelerometer output thermal drift is calculated. And the relationship between adhesive void and the output thermal drift of micro-accelerometer indicates that the increase in the distance between the void and the center of the adhesive layer will result in the up-down-up thermal drift trend. and larger void will generate higher thermal drift. The thermal drift caused by two adhesive void simultaneously is roughly equal to the sum of the drift caused by these two void separately.