Drop test device for a micromechanical component

Abstract

The invention relates to a drop test device for a micromechanical component comprising a drop body (100) with a shell (110) and with an interior (120) for receiving at least one micromechanical component (1).

Description

State of the art

[0001] To determine the mechanical robustness of MEMS sensors, drop tests are typically performed in the prior art. In these tests, unsoldered sensors are usually dropped from a height of, for example, 2 meters onto a plate, such as one made of granite. This deflects the movable MEMS structure in a random direction, causing it to strike the stationary elements of the MEMS in that same direction. Electrical measurements of the sensors are then taken to determine whether any signals indicate a mechanical defect. If a defect is found, the sensor core is analyzed for mechanical damage using imaging techniques (such as infrared or SEM). Based on the specific damage findings, design optimizations for the MEMS can then be implemented.

[0002] In sensors encased in a chip package, for example made of plastic, the actual silicon-based MEMS sensor does not make direct contact with the base plate during drop tests. However, in MEMS sensors housed in a chip-scale package, the silicon components of the MEMS and the ASIC are exposed. Therefore, direct impact of the silicon against the hard base plate can cause significant damage to the sensor's outer casing, obscuring the actual test objective: inducing damage to the internal moving micromechanical structures. Object of the invention

[0003] The object of the invention is to create a drop test device for a micromechanical (MEMS) component, which is designed to subject the MEMS component to an impact from free fall without damaging it externally. Advantages of the invention

[0004] The invention relates to a drop test device for a micromechanical component comprising a drop body with a shell and with an interior space for receiving at least one micromechanical component. To examine micromechanical components in an undirected drop test, they are placed in a drop body, for example made of plastic, according to the invention. This prevents mechanical damage to the outer shell.

[0005] Particularly in the case of micromechanical components in a chip-scale package, mechanical damage to the exposed silicon substrates is advantageously prevented.

[0006] An advantageous embodiment of the invention provides that the micromechanical component can be placed inside the casing and connected to it in a form-fit and / or force-fit manner. This advantageously protects the component from hard impacts on a surface. Nevertheless, the shock from the impact of the falling object on a hard surface is transferred to the micromechanical structures inside the MEMS component.

[0007] An advantageous embodiment of the invention provides that the falling body is spherical. This advantageously avoids chaotic impact scenarios.

[0008] An advantageous embodiment of the invention provides that the casing is composed of two hemispheres. Advantageously, the micromechanical component can thus be placed in the center of the falling body, in the interior space formed by a recess in the hemispheres.

[0009] An advantageous embodiment of the invention provides that a test board for receiving the micromechanical component is arranged in the interior and that the micromechanical component can be connected to the test board by a positive fit, a force fit, and / or a material bond. Advantageously, the micromechanical component is mounted on the test board in the same way as in the later application on a printed circuit board with similar mounting and impact load. Advantageously, the micromechanical component is only attached to the test board, so that the remaining interior space can be freely designed and micromechanical components of various sizes and shapes can be positioned therein, as long as they are only attached to the test board.

[0010] On the one hand, avoiding external damage makes the actual drop test, or rather impact test, possible for components in chip-scale packages; on the other hand, another aspect of the old test is significantly improved: Previously, impacts on a corner or edge of the sensors could generate strong moments that depended not only on the operator of the machine (position and initial rotation of the sensor at the moment of drop), but were also impossible to simulate or predict due to their chaotic and random nature. The radially uniform distribution of impact points across the sphere's surface and the center of mass at the sphere's center minimize chaotic impact scenarios and make the experiment easier to simulate. This has the advantage that potential damage to the MEMS structures is more easily traceable and thus comparable with alternative designs. drawing Fig. Figure 1 schematically shows a micromechanical device in an LGA package in the prior art. Fig. Figure 2 schematically shows a micromechanical device in a bare-die chip-scale package in the prior art. Fig. Figure 3 schematically shows a drop test device according to the invention in the form of a spherical drop body in a first embodiment. Fig. Figure 4 schematically shows a drop test device according to the invention in the form of a spherical drop body in a second embodiment. Description

[0011] Fig. Figure 1 schematically shows a prior art micromechanical device in an LGA package. An ASIC chip 10 and a micromechanical (MEMS) chip 20 are stacked on top of each other and surrounded by a substrate printed circuit board (PCB) 30 on the bottom and potting compound 40 on the top and sides. Solder balls 50 are arranged on the underside of the PCB. A drop test of such a packaged MEMS component results in only minimal traces.

[0012] Fig. Figure 2 schematically shows a micromechanical device in a prior art bare-die chip-scale package. The stacked silicon substrates of MEMS chip 20 and ASIC chip 30 are exposed. During a drop test of such a packaged MEMS component, damage to the silicon, such as chip breakage or chipping, particularly at corners and edges, can occur upon impact with a hard surface.

[0013] Fig. Figure 3 schematically shows a drop test device according to the invention in the form of a spherical drop body in a first embodiment. The drop test device comprises a drop body 100 with a shell 110 and an interior 120 for receiving a micromechanical component 1. The figure shows a micromechanical component in a chip-scale package, installed in a drop body 100 with a shell 110 in the form of a sphere, consisting of two hemispheres 111, 112. The drop body is designed to fall freely and impact a surface. The micromechanical component is mounted in the drop body and protected by the shell. Thus, the micromechanical component experiences the impact event upon impact of the drop body on the surface without sustaining external damage.

[0014] Fig.Figure 4 schematically shows a drop test device according to the invention in the form of a spherical drop body in a second embodiment. The figure shows a micromechanical component 1 in a chip-scale package, soldered by means of solder balls 50 onto a test board 130 inside a sphere consisting of two hemispheres 111, 112. The micromechanical component is mounted in the drop body on the test board and protected by the casing. Reference symbol list 1 micromechanical component 10 ASIC Chip 20 micromechanical (MEMS) chip 30 Substrate printed circuit board (PCB) 40 potting compound 50 solder balls 100 falling bodies 110 case 111, 112 hemispheres 120 interior 130 test boards

Claims

[1] Drop test device for a micromechanical component comprising a drop body (100) with a shell (110) and with an interior (120) for receiving at least one micromechanical component (1). [2] Drop test device according to claim 1, characterized by , that the micromechanical component (1) can be placed in the interior (120) and connected to the shell (110) in a form-fitting and / or force-fitting manner. [3] Drop test device according to claim 1, characterized by , that the falling body (100) is spherical. [4] Drop test device according to claim 3, characterized by , that the shell (110) is composed of two hemispheres (111, 112). [5] Drop test device according to any one of the preceding claims 1 to 4, characterized by, that a test board (130) for receiving the micromechanical component (1) is arranged in the interior (120) and that the micromechanical component can be connected to the test board 2 in a form-fitting and / or force-fitting and / or material-fitting manner.

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