Multilayer ceramic capacitors (MLCC) are the most 5 widely used capacitor type in the electronics industry. However, 6 the brittle ceramic dielectric makes MLCCs prone to mechanical 7 damage. Manufacturing defects or damage during board assembly 8 may cause a capacitor to prematurely fail during its operational 9 life. Here, we demonstrate the fast and non-destructive acoustic 10 screening of MLCCs. Soldered 2220-sized MLCCs were subjected 11 to ac voltage frequency sweeps, causing them to vibrate mechan-12 ically. Acoustic responses of the capacitors were measured before 13 and after subjecting the test circuit board to severe bending. The 14 results show that the cracks and delaminations caused by bending 15 induce characteristic changes in the capacitors' acoustic response. 16 A support vector machine classifier was trained to successfully 17 detect damaged capacitors based on their acoustic response. 18 Index Terms-Acoustic emission, ceramic capacitors, nonde-19 structive testing. 20 I. INTRODUCTION 21 M ULTILAYER ceramic capacitors (MLCCs) are com-22 monly used in the electronics industry [1]. The ceramic 23 dielectric gives MLCCs high capacitance per volume, but also 24 makes them prone to mechanical damage. 25 Voids and delaminations are typical manufacturing defects in 26 MLCCs, often related to thermal stresses [2], [3]. Mechanical 27 stress, such as improper printed circuit board (PCB) handling 28 during assembly, can lead to cracks or delamination in MLCCs 29 [4], [5]. Mechanical damage in MLCCs is often left unrec-30 ognized during production or assembly, as the capacitor may 31 operate normally electrically. However, in the field, a crack or 32 delamination in an MLCC may grow in size, resulting in loss of 33

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Heat flux sensors have potential in enabling applications that require direct and instantaneous tracking of thermal energy transfer. To facilitate widespread use of the sensors, the sensors have to be robust and feasible to implement, while maintaining high sensitivity, fast response time, and low thermal obtrusiveness. However, most currently available heat flux sensors are either challenging to manufacture or ill-suited for surface heat flux measurement because of their mechanical or thermal characteristics. In this paper, the design of a novel MEMS heat flux sensor structure intended for surface heat flux measurements is presented. A prototype batch is manufactured and the electrical performance of the prototype sensors is compared with commercially available heat flux sensors. Results show that sensors with a similar sensitivity as commercial sensors can be made by using MEMS methods.

Multilayer ceramic capacitors (MLCC) are the most widely used capacitor type in the electronics industry. However, the brittle ceramic dielectric makes MLCCs prone to mechanical damage. Manufacturing defects or damage during board assembly may cause a capacitor to prematurely fail during its operational life. Here, we demonstrate the fast and non-destructive acoustic screening of MLCCs. Soldered 2220-sized MLCCs were subjected to ac voltage frequency sweeps, causing them to vibrate mechanically. Acoustic responses of the capacitors were measured before and after subjecting the test circuit board to severe bending. The results show that the cracks and delaminations caused by bending induce characteristic changes in the capacitors' acoustic response. A support vector machine classifier was trained to successfully detect damaged capacitors based on their acoustic response. Index Terms-Acoustic emission, ceramic capacitors, nondestructive testing. I. INTRODUCTION M ULTILAYER ceramic capacitors (MLCCs) are commonly used in the electronics industry [1]. The ceramic dielectric gives MLCCs high capacitance per volume, but also makes them prone to mechanical damage. Voids and delaminations are typical manufacturing defects in MLCCs, often related to thermal stresses [2], [3]. Mechanical stress, such as improper printed circuit board (PCB) handling during assembly, can lead to cracks or delamination in MLCCs [4], [5]. Mechanical damage in MLCCs is often left unrecognized during production or assembly, as the capacitor may operate normally electrically. However, in the field, a crack or delamination in an MLCC may grow in size, resulting in loss of Manuscript