Sensor with dust-proof / noise-resistant structure

Abstract

To provide a sensor (e.g., a pressure sensor) having a dust- and noise-resistant structure and high workability of a lead.SOLUTION: A sensor includes a sensor element, a housing that houses the sensor element, a lead frame that is connected to external wiring, a cover plate that together with the lead frame forms a space surrounding the sensor element, and a port cover that has an outside air inlet hole and is arranged to cover the cover plate in a non-contact manner. In the sensor, the cover plate is fixed to the housing or port cover at multiple points, and only one of the multiple points is electrically connected to the lead frame through a connection with a conductive material to maintain a predetermined potential.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sensor having a dust-proof / noise-proof structure. [Background technology]

[0002] Conventionally, a known pressure sensor detects pressure by converting strain detected by a pressure-sensitive element such as a diaphragm into an electrical signal using a piezoresistor or the like. A known structure involves packaging a pressure-sensitive unit using this type of system and exposing the pressure-sensitive element to outside air (the gas whose pressure is to be measured or the outside air used to acquire atmospheric pressure) through an air inlet hole provided in the package (see, for example, Patent Documents 1 and 2). Another known structure involves sealing such a pressure-sensitive unit with a liquid such as silicone oil, which also serves as a pressure transmission medium (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-185214 [Patent Document 2] U.S. Patent No. 1,065,4709 [Patent Document 3] Patent No. 6820247 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in the pressure sensors disclosed in the above-mentioned Patent Documents 1 and 2, the pressure-sensitive element is exposed to the outside air introduced through the outside air inlet, and therefore is structured so as to be susceptible to adverse effects from dust or noise contained in the outside air. Also, since the leads of the pressure sensor have steps, it is desirable that the leads be highly workable, but for example, when a cover plate is provided on top of the pressure-sensitive element for the purpose of dust / noise resistance and the cover plate is fixed to the leads, there is a risk that the workability of the leads will be reduced if there are many fixing points.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has as its final object to provide a sensor that has a dust-proof / noise-proof structure and has leads that are easy to process. [Means for solving the problem]

[0006] A sensor element; a housing having a recess and accommodating the sensor element in the recess; a lead frame connectable to external wiring and to which electrodes of the sensor element are connected; a cover plate disposed opposite the bottom surface of the recess; a port cover having an outside air introduction hole and arranged to cover the cover plate, The sensor is characterized in that the cover plate is fixed to the housing or the port cover at multiple points, and at least one of the multiple points is electrically connected to the lead frame and maintained at a predetermined potential.

[0007] In the present invention, by electrically connecting the cover plate to the lead frame at at least one location, the potential of the cover plate can be maintained at the potential of a specific lead frame, and the processability of the lead frame can be improved. The fewer the connection locations on the lead frame, the easier it is to deform the lead frame, thereby improving the processability.

[0008] The present invention may also provide a sensor characterized in that the lead frame has a flat portion on the bottom surface of the recess of the housing on which the sensor element is placed, and the cover plate is disposed opposite the flat portion and, together with the flat portion, forms a space surrounding the sensor element. This reduces the adverse effects of dust because gas introduced into the sensor through the air inlet hole does not blow directly onto the surface of the sensor element but instead moves inside the package by an airflow that bypasses the cover plate. This also reduces the adverse effects of external noise.

[0009] In addition, the present invention may provide a sensor characterized in that the at least one location of the cover plate is electrically connected to the lead frame via a connection part having a through hole filled with a conductive material. This allows the cover plate to be more stably connected to the lead frame. Furthermore, since the cover plate can be fixed at an appropriate position on the housing, design freedom can be increased.

[0010] The present invention may also provide a sensor characterized in that the cover plate is at least partially made of metal and is positioned higher than the surfaces of the sensor element and the lead frame. In this case, the cover plate is electrically conductive. Furthermore, because metal materials have good thermal conductivity, even in situations where the sensor is exposed to a sudden temperature change and condensation occurs, condensation occurs on the cover plate rather than the sensor element, thereby protecting the sensor element from condensation. Furthermore, by positioning the cover plate higher than the surfaces of the sensor element and the lead frame, for example, when the sensor element and the lead frame are connected to a signal processing element by wires, the risk of the wires coming into contact with the cover plate and causing a short circuit can be reduced.

[0011] The present invention may also provide a sensor in which the lead frame has inner leads that are formed inside the housing in a plan view and outer leads that are formed outside the housing in a plan view, and the connection portion is located on a line connecting the inner leads and the outer leads in a plan view. This allows the cover plate and the lead frame to be reliably connected over a shorter distance. Furthermore, the structure can be simplified and reliability can be improved.

[0012] In addition, the present invention may be a sensor characterized in that the height of the cover plate can be adjusted by changing the depth of the through hole of the connection portion relative to the surface of the inner lead. By adjusting the height of the cover plate, it is possible to adjust the volume of the flow path for gas introduced through the outside air inlet, for example.

[0013] The present invention may also provide a sensor characterized in that the connection portion is disposed on either the GND or VDD lead frame, thereby maintaining the sensor at a predetermined potential as described above.

[0014] In addition, the present invention may be a sensor characterized in that the portion other than the connection portion is fixed to the housing at the upper part of the lead frame via an insulating fixing portion, whereby the fixing portion has insulating properties and therefore it is possible to reduce the risk of short-circuiting at the fixing portion.

[0015] Furthermore, the present invention may provide a sensor characterized in that the fixing portion is a bottomed or bottomless hole filled with an insulating material, or a bottomed hole filled with a conductive material. If the fixing portion is a bottomed hole, the cover plate is not connected to the lead frame via the fixing portion, so there is no risk of short circuiting even if the fixing portion is filled with a conductive material. Therefore, the fixing portion may be filled with either an insulating material or a conductive material. When the fixing portion is a bottomless hole, it can be formed more easily than when it is a bottomed hole.

[0016] The present invention may also provide a sensor in which the cover plate is integrally molded with the port cover such that a flow path exists from the outside air inlet to the inside of the housing. This allows the metal cover to be fixed to the housing simply by attaching the port cover to the housing. It also allows a flow path from the outside world to the sensor element, bypassing the metal plate.

[0017] In addition, in the present invention, the sensor may be characterized in that the cover plate is made of a multi-layer substrate, and by using a conductive layer as an intermediate layer, for example, the conductive layer is exposed to the outside air, and contamination or short circuits caused by foreign matter from the outside air adhering thereto can be suppressed.

[0018] The above means for solving the problems can be used in combination with each other whenever possible. [Effects of the Invention]

[0019] The present invention provides a sensor that has a dust-proof / noise-proof structure and high lead workability. Furthermore, by reducing the number of bonding points of the cover plate to the leads, the sensor can be made smaller. [Brief explanation of the drawings]

[0020] [Figure 1] Fig. 1A is a top view showing the appearance of a pressure sensor according to Example 1 of the present invention. Fig. 1B is a first schematic cross-sectional view showing the internal structure of the pressure sensor according to Example 1. Fig. 1C is a second schematic cross-sectional view showing the internal structure of the pressure sensor according to Example 1. [Figure 2] FIG. 2 is an explanatory diagram showing the flow of gas introduced into the pressure sensor according to the first embodiment. [Figure 3]3A and 3B are explanatory diagrams showing enlarged views of a part of the configuration shown in FIG. 1C. [Figure 4] FIG. 4 is a transparent top view showing the internal structure of the pressure sensor according to the first embodiment of the present invention. [Figure 5] FIG. 5A is a first diagram illustrating the flow of manufacturing the pressure sensor according to Example 1 of the present invention. FIG. 5B is a second diagram illustrating the flow of manufacturing the pressure sensor according to Example 1 of the present invention. FIG. 5C is a third diagram illustrating the flow of manufacturing the pressure sensor according to Example 1 of the present invention. FIG. 5D is a fourth diagram illustrating the flow of manufacturing the pressure sensor according to Example 1 of the present invention. FIG. 5E is a fifth diagram illustrating the flow of manufacturing the pressure sensor according to Example 1 of the present invention. [Figure 6] 6A and 6B are transparent top views showing the internal structure of a pressure sensor according to a second embodiment of the present invention. [Figure 7] Fig. 7A is a schematic cross-sectional view showing the internal structure of a pressure sensor according to Example 3 of the present invention, and Fig. 7B is an explanatory view showing an enlarged view of a part of the configuration shown in Fig. 7A. [Figure 8] 8A is a top view showing the outermost layer of a cover plate according to Example 4 of the present invention, and FIG. 8B is a top view and a see-through top view showing the outermost layer and an intermediate layer of a cover plate according to Example 4. [Figure 9] Fig. 9A is a transparent top view showing the appearance of a pressure sensor according to Example 5 of the present invention. Fig. 9B is a side view showing a cover plate integrally molded with a port cover according to Example 5. Fig. 9C is a schematic cross-sectional view showing the internal structure of a pressure sensor according to Example 5 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] [Application example] An outline of an application example of the present invention will be explained below with reference to some of the drawings. The present invention can be applied to pressure sensors such as those shown in FIGS. 1A, 1B, and 1C. FIG. 1A is a top view showing the appearance of pressure sensor 1 according to an application example. FIG. 1B is a schematic cross-sectional view showing the AA cross section of pressure sensor 1 shown in FIG. 1A. FIG. 1C is a schematic cross-sectional view showing the BB cross section of pressure sensor 1 shown in FIG. 1A. Note that outer lead 33a of lead 33, which is a connection terminal with external wiring, is omitted in FIG. 1A.

[0022] As shown in FIGS. 1A, 1B, and 1C, the pressure sensor 1 includes a package consisting of a case 30 and a port cover 40, and contains a MEMS (Micro Electro Mechanical Systems) sensor chip 10 and an ASIC (Application Specific Integrated Circuit) 20 connected to the MEMS sensor chip 10 via wires 71. The ASIC 20 is not essential to the pressure sensor 1; if the sensor size or cost is to be reduced, only the MEMS sensor chip 10 may be included. The ASIC 20 includes a power supply circuit, a signal conditioning circuit, an analog-to-digital conversion circuit, and other circuits. Having the ASIC 20 and the MEMS sensor chip 10 in the same package is advantageous in terms of ease of signal and power handling and noise reduction. Here, the MEMS sensor chip 10 and the case 30 in this application example correspond to the sensor element and the housing, respectively, in the present invention.

[0023] The MEMS sensor chip 10 includes a pressure reference chamber 11, a diaphragm 12, and a plurality of piezoresistance elements 13 (omitted in FIGS. 1A, 1B, and 1C) provided along the periphery of the diaphragm 12. The piezoresistance elements 13 are a type of sensor that can generate an electrical signal corresponding to the deformation of the diaphragm 12 when the diaphragm 12 is deformed due to the difference between the pressure inside the pressure reference chamber 11 and the external pressure. In this application example, four piezoresistance elements 13 are provided at equal intervals along the periphery of the diaphragm 12. However, the MEMS sensor chip 10 is not limited to this, and may be configured to include any number of piezoresistance elements 13 depending on the required accuracy.

[0024] The pressure reference chamber 11 communicates with a reference pressure introducing hole 31 provided in the case portion 30, and outside air serving as a reference pressure is introduced through the reference pressure introducing hole 31. Meanwhile, gas whose pressure is to be measured is introduced into the package through a pressure guiding hole 41 provided in the port cover portion 40. In other words, the pressure sensor 1 according to this application example is a differential pressure sensor in which the outside air introduced through the reference pressure introducing hole 31 serves as a reference pressure. Here, the pressure guiding hole 41 in this application example corresponds to the outside air introducing hole in the present invention.

[0025] 1B and 1C, the pressure-conducting hole 41 and the surface of the MEMS sensor chip 10 (i.e., the side where the piezoresistive elements 13 are provided) are arranged in a positional relationship facing each other, but a cover plate 50 is provided in a position that blocks the two. In FIG. 1C, the areas surrounded by dotted lines (a) and (b) include the locations where the cover plate 50 is fixed to the case part 30. Details will be explained below with reference to FIGS. 3A and 3B. Here, the cover plate 50 is a plate-like member formed, for example, from a conductive metal material. Note that the cover plate 50 is configured to cover the entire MEMS sensor chip 10 and the ASIC 20, but this is not necessarily the case as long as it covers the area on the surface of the MEMS sensor chip 10 that includes the piezoresistive elements 13. For example, it is also possible to configure the cover plate 50 so as not to cover the ASIC 20.

[0026] In this way, since the pressure sensor 1 according to this application example is provided with the cover plate 50, the gas introduced into the pressure sensor 1 from the pressure introducing hole 41 does not blow directly onto the surfaces of the MEMS sensor chip 10 and the ASIC 20, but moves inside the package as an airflow that bypasses the cover plate 50. In FIG. 2, the flow of the gas introduced from the pressure introducing hole 41 is indicated by white arrows. The gas flowing in from the pressure guide hole 41 passes through the narrow space between the cover plate 50 and the port cover portion 40, then passes between the side surface of the cover plate 50 and the side wall of the case portion 30, and reaches the MEMS sensor chip 10 and the ASIC 20. By detouring and passing through the narrow space, the possibility of dust contained in the gas adhering to the MEMS sensor chip 10 is reduced. Furthermore, the provision of the cover plate 50 can also reduce the adverse effects of external noise.

[0027] As described above, the pressure sensor 1 according to this application example can suppress the adverse effects of dust and noise even when the pressure introducing hole 41 and the surface of the MEMS sensor chip 10 are positioned in an opposing relationship. That is, by providing the cover plate 50, the pressure introducing hole 41 can be diverted by the cover plate 50 regardless of its position. This allows the pressure introducing hole 41 to be freely laid out without considering the adverse effects of dust and noise. Furthermore, by forming the cover plate 50 from a metal material, even in situations where the pressure sensor 1 is exposed to a sudden temperature change and condensation occurs, condensation occurs on the cover plate 50, not on the MEMS sensor chip 10, thereby protecting the MEMS sensor chip 10 from condensation. This is because metal materials have good thermal conductivity, and condensation occurs before condensation occurs on the case 30, which is made of resin.

[0028] FIG. 3A is an explanatory diagram showing an enlarged view of the area surrounded by the dotted line (a) in FIG. 1C. One end of the cover plate 50 shown in FIG. 3A is fixed to the case 30 by a fixing portion 63a. The hole of the fixing portion 63a is formed on the case 30, but has a bottom and does not penetrate to the lead 33. In other words, one end of the cover plate 50 shown in FIG. 3A is not electrically connected to the lead 33. As shown in FIGS. 3A and 3B, in a side view, the depth of the hole of the fixing portion 63a is shallower than the depth of the hole of the connection portion 64. In contrast, FIG. 3B is an explanatory diagram showing an enlarged view of the area surrounded by the dotted line (b) in FIG. 1C. The other end of the cover plate 50 shown in FIG. 3B is fixed to the case 30 by a connection portion 64. The hole of the connection portion 64 has no bottom and penetrates from the top of the case 30 to the lead 33. 3B is electrically connected to the lead 33. Note that the cover plate 50 is electrically connected to the lead 33 only at one point, the connection portion 64.

[0029] The lead 33 electrically connected to the other end of the cover plate 50 shown in Fig. 3B is further grounded to GND or VDD. In the present invention, the state in which the cover plate 50 is maintained at a predetermined potential refers to the state in which the cover plate 50 is grounded to GND or VDD via the connection portion 64 and the lead 33 at any location (the arrangement of the other end of the cover plate 50 shown in Fig. 3B is merely an example, and the position of the connection portion 64 is not limited thereto).

[0030] Example 1 Hereinafter, a pressure sensor 1 according to a first embodiment of the present invention will be described in more detail with reference to the drawings (including the drawings that were explained in the application examples above). Note that the pressure sensor according to the present invention is not intended to be limited to the following configuration. Furthermore, in the following embodiments, a pressure sensor is exemplified as an example of a sensor, but the present invention is not limited to this and other types of sensors may also be used.

[0031] <Pressure sensor configuration> Returning now to the explanation of Fig. 1, the pressure sensor 1 according to the first embodiment has a configuration in which a MEMS sensor chip 10 and an ASIC 20 are housed in a rectangular package consisting of a case part 30 and a port cover part 40, as shown in Figs. 1A, 1B, and 1C. That is, since it has the same configuration as the pressure sensor 1 explained in the application example, a detailed explanation of the contents explained in the application example will be omitted. Also, in this specification, the same components will be referred to as the same parts. The explanation will be given using symbols.

[0032] 1B and 1C, the MEMS sensor chip 10 and the ASIC 20 are fixed and placed on the lead plane 32 on the bottom surface of the recess of the case part 30 by a die bond resin 60. The MEMS sensor chip 10 and the ASIC 20, together with the lead plane 32 fixed by the die bond resin 60, are housed in a space surrounded by a cover plate 50. Here, the lead plane 32 in this embodiment corresponds to the flat portion in the present invention.

[0033] As shown in FIG. 1B, the port cover portion 40 is fixed to the case portion 30 by a cover bond resin 62 and is disposed so as to cover the cover plate 50.

[0034] 4 is a transparent top view showing the internal structure of the pressure sensor 1 according to the first embodiment of the present invention. In detail, this is a top view showing the port cover portion 40 and the cover plate 50 of the pressure sensor 1 in a transparent state. The MEMS sensor chip 10 has a plurality of piezoresistor elements 13 provided along the periphery of the diaphragm 12 on the front surface side, and a plurality of electrode pads 14. The ASIC 20 also has a plurality of electrode pads 21 on the front surface side, and the electrode pads 14 of the MEMS sensor chip 10 and some of the electrode pads 21 of the ASIC 20 are connected by conductive wires 71.

[0035] In FIG. 4 , the leads 33 include outer leads 33a that extend outside the case 30 in a plan view (specifically, the outer leads 33a are positioned outside the cover bond resin 62 in a plan view), and inner leads 33b that are positioned inside the case 30 in a plan view (specifically, the inner leads 33b are positioned inside the cover bond resin 62 in a plan view). The electrode pads 21 of the ASIC 20 are connected by wires 71 to the inner leads 33b, which serve as connection terminals for connecting to external wiring, and to the lead plane 32, which also serves as the die pad and inner leads 33b. The cover plate 50 is positioned higher than the surface where the electrode pads 21 are connected to the inner leads 33b and the lead plane 32 by the wires 71. (More specifically, the cover plate 50 is positioned higher than the surfaces of the MEMS sensor chip 10 and the ASIC 20.) The wires 71 are connected to the electrodes by wire bonding. The lead plane 32 and the leads 33 in this embodiment correspond to the lead frame in the present invention. It should be noted that it is not always necessary to use the lead plane 32 and the leads 33 as long as they are configured to be connectable to external wiring.

[0036] As shown in FIG. 3 , the cover plate 50 is fixed to the case 30 at two locations: the fixed portion 63 a and the connecting portion 64. Furthermore, as shown in FIG. 3 , the cover plate 50 is electrically connected to the leads 33 only at the connecting portion 64. Fixing the cover plate 50 to the case 30 at two locations: the fixed portion 63 a and the connecting portion 64 allows the pressure sensor 1 to be miniaturized while maintaining a certain level of fixation strength. Furthermore, since the cover plate 50 is electrically connected to the leads 33 only at the connecting portion 64, the processability of the leads 33 is improved, making it easier to provide steps in the leads 33, for example. Furthermore, the cover plate 50 can be connected only to the GND or VDD of the MEMS sensor chip 10, preventing short-circuiting with electrodes at other potentials. Furthermore, the potential of the cover plate 50 can be set to GND or VDD, thereby enhancing the shielding effect of the MEMS sensor chip 10 and the ASIC 20 and improving noise resistance. Furthermore, both the fixed portion 63a and the connection portion 64 are located on the line connecting the outer lead 33a and the inner lead 33b in a planar view (strictly speaking, in the case of the connection portion 64, it is located on the line connecting the outer lead 33a and the lead plane 32 which also serves as the die pad and inner lead 33b in a planar view).

[0037] <Pressure sensor manufacturing flow> 5A to 5E, a manufacturing flow of the pressure sensor 1 according to this embodiment will be described. Fig. 5A is a schematic cross-sectional view showing a state in which the lead plane 32 and the leads 33 are joined to the case part 30 having the reference pressure introducing hole 31 in the manufacturing flow of the pressure sensor 1. The MEMS sensor chip 10 and the ASIC 20 are mounted (die-bonded) on the lead plane 32 in this state using a die-bond resin 60, and the electrode pads 14, the electrode pads 21, the lead plane 32, and the inner leads 33b are connected by wire bonding with wires 71 (Fig. 5B).

[0038] Thereafter, the cover plate 50 is fixed to the case portion 30 by the fixing portions 63a and the connecting portions 64 (FIG. 5C). Furthermore, a cover bond resin 62 is applied near the upper end of the case portion 30 (FIG. 5D), and the port cover portion 40 having the pressure introducing hole 41 is bonded to the case portion 30 by the cover bond resin 62, and the package is sealed (FIG. 5E). Note that the cover bond resin 62 must completely seal the port cover portion 40 and the case portion 30 to prevent gas leakage. Then, the lead planes 32 and leads 33 are singulated to complete one pressure sensor chip.

[0039] Example 2 Next, a pressure sensor 2 according to a second embodiment of the present invention will be described with reference to Figures 6A and 6B. The pressure sensor 2 has many components in common with the pressure sensor 1 of the first embodiment, and therefore, the same components are denoted by the same reference numerals and will not be described again. The components shown in the pressure sensor 2 can also be applied to the pressure sensor 1 of the first embodiment.

[0040] <Pressure sensor configuration> 6A and 6B are transparent top views showing the internal structure of pressure sensor 2 according to Example 2 of the present invention. The number of holes in fixing portion 63a in pressure sensor 2 shown in FIG. 6A is greater than the number of holes in fixing portion 63a in pressure sensor 1 shown in FIG. 4 of Example 1 (hereinafter, all fixing portions 63a shown in FIG. 6A will be referred to as "island-shaped fixing portions"). In addition, the area of ​​the holes in fixing portion 63b in pressure sensor 2 shown in FIG. 6B is greater than the area of ​​the holes in fixing portion 63a in pressure sensor 1 shown in FIG. 4 of Example 1 (hereinafter, all fixing portions 63b shown in FIG. 6B will be referred to as "linear fixing portions"). In FIG. 6B, connecting portion 64 is formed on a linear fixing portion.

[0041] The area of ​​the opening of the hole in the island-shaped fixing portion and the area of ​​the opening of the hole in the linear fixing portion are both larger than the area of ​​the opening of the fixing portion 63a shown in Fig. 4. That is, in the pressure sensor 2 according to Example 2, the fixing strength of the cover plate 50 to the case portion 30 is higher than that of the pressure sensor 1 according to Example 1.

[0042] 6A and 6B, the area of ​​the opening of the hole in the island-shaped fixing portion is smaller than the area of ​​the opening of the hole in the linear fixing portion. That is, in manufacturing the pressure sensor 2, if priority is given to reducing the cost required to fix the cover plate 50 to the case portion 30, it is desirable to use the island-shaped fixing portion, and if priority is given to increasing the fixing strength of the cover plate 50 to the case portion 30, it is desirable to use the linear fixing portion.

[0043] Example 3 Next, a pressure sensor 3 according to a third embodiment of the present invention will be described with reference to Figures 7A and 7B. The pressure sensor 3 has many components in common with the pressure sensor 1 of the first embodiment, and therefore, the same components are denoted by the same reference numerals and will not be described again. The configuration of the pressure sensor 3 can also be applied to the pressure sensors 1 and 2 of the first and second embodiments.

[0044] <Pressure sensor configuration> FIG. 7A is a schematic cross-sectional view showing the internal structure of a pressure sensor 3 according to Example 3 of the present invention. Similar to pressure sensor 1 of Example 1 and pressure sensor 2 of Example 2, the cover plate 50 is electrically connected to the leads 33 only at one point via a connection portion 64. FIG. 7B is an explanatory diagram showing an enlarged view of the area surrounded by the dotted line (c) in FIG. 7A. The cover plate 50 is fixed to the case portion 30 by a fixing portion 63c. The fixing portion 63c has a bottomless hole that penetrates from above the case portion 30 to the leads 33. This allows for a higher fixing strength than the fixing portion 63a in pressure sensor 1 of Example 1. It is essential that the fixing portion 63c be made of an insulating material to prevent the cover plate 50 from being electrically connected to the leads 33 via the fixing portion 63c and damaging the pressure sensor 3 due to a short circuit.

[0045] Example 4 8A and 8B, a cover plate 50a according to a fourth embodiment of the present invention will be described. The cover plate 50a can be applied to the pressure sensors 1, 2, and 3 of the first to third embodiments (i.e., can be used in place of the cover plate 50).

[0046] <Cover plate configuration> FIG. 8A is a top view showing the outermost layer of a cover plate 50a according to Example 4 of the present invention. In Example 1, the cover plate 50 is illustrated as a plate-like member formed of a conductive metal material. However, the entire surface does not need to be formed of a conductive metal material. As shown in FIG. 8A, the cover plate 50a may include an insulating film 52 as long as the conductive film 51 is electrically connected to the connection portion 64. FIG. 8B is a top view and a see-through top view showing the outermost layer and intermediate layer of the cover plate 50a according to Example 4. The upper view in FIG. 8B shows the outermost layer formed only of the insulating film 52, excluding the connection portion 64. The lower view in FIG. 8B shows the intermediate layer formed of the insulating film 52, including the portion where the conductive film 51 is electrically connected to the connection portion 64. FIG. 8B shows the cover plate 50a as a printed circuit board. Either the cover plate 50a shown in FIG. 8A or the cover plate 50a shown in FIG. 8B may be applied to the pressure sensors 1, 2, and 3 described in Examples 1 to 3.

[0047] Example 5 Next, a pressure sensor 4 according to a fifth embodiment of the present invention will be described with reference to Figures 9A, 9B, and 9C. The pressure sensor 4 shares many components with the pressure sensor 1 of the first embodiment, and therefore, the same components are denoted by the same reference numerals and will not be described again. The configuration shown in the pressure sensor 4 can be applied to the pressure sensors 1, 2, and 3 of the first to third embodiments. The cover plate 50a of the fourth embodiment can be applied to the pressure sensor 4.

[0048] <Pressure sensor configuration> FIG. 9A is a transparent top view showing the appearance of a pressure sensor 4 according to a fifth embodiment of the present invention. As shown in FIG. 9A, the area of ​​the cover plate 50b is smaller than the area of ​​the port cover portion 40a in a plan view (in FIG. 9A, the port cover portion 40a covers the cover plate 50b). FIG. 9B is a side view of the port cover portion 40a and the cover plate 50b in the pressure sensor 4 shown in FIG. 9A. As shown in FIG. 9B, the cover plate 50b is integrally molded with the port cover portion 40a. In a side view, the cover plate 50b is closely fixed to the right side of the port cover portion 40a in FIG. 9B, and a space is generated between the port cover portion 40a and the cover plate 50b on the left side of the port cover portion 40a. Conversely, the cover plate 50b may be closely fixed to the left side of the port cover portion 40a, and a space may be generated between the port cover portion 40a and the cover plate 50b on the right side of the port cover portion 40a. FIG. 9C is a side view of the pressure sensor 4 shown in FIG. 9A. 9C is a schematic cross-sectional view showing the CC cross section of FIG. 4. Gas flowing in from pressure introducing hole 41a passes through a narrow space between cover plate 50b and port cover portion 40a, but this narrow space is formed only on the left side in FIG. 9C (or FIG. 9B). Therefore, the gas that flows in tends to bypass cover plate 50b in one direction, without branching and bypassing cover plate 50b in two directions.

[0049] In the manufacturing flow of the pressure sensor 4, by integrally molding the port cover portion 40a with the cover plate 50b, sufficient fixing strength can be obtained by fixing the port cover portion 40a to the case portion 30 with the cover bond resin 62, even if the cover plate 50b is not fixed to the case portion 30 with the fixing portions 63a, 63b, and 63c. It is also possible to reduce the number of mounting steps.

[0050] <Appendix 1> A sensor element (10); a housing (30) having a recess and accommodating the sensor element in the recess; lead frames (32, 33) that can be connected to external wiring and to which electrodes of the sensor element are connected; a cover plate (50, 50a, 50b) disposed opposite the bottom surface of the recess; a port cover (40, 40a) having an outside air introduction hole (41, 41a) and arranged to cover the cover plate, The cover plate is fixed to the housing or the port cover at multiple locations (63a, 63b, 63c, 64), and one of the multiple locations is electrically connected to the lead frame to be maintained at a predetermined potential. [Explanation of symbols]

[0051] 1, 2, 3, 4: Pressure sensors 10: MEMS sensor chip 11: Pressure reference chamber 12: Diaphragm 13: Piezoresistive element 14, 21: Electrode pads 20: ASIC 30: Case part 31: Reference pressure introduction hole 32: Lead plane 33: Lead 33a: Outer lead 33b: Inner lead 40, 40a: Port cover 41, 41a: Pressure hole 50, 50a, 50b: Cover plate 51: Conductive film 52: insulating film 60: Die bond resin 62: Cover bond resin 63a, 63b, 63c: Fixed part 64: Connection 71: Wire

Claims

1. A sensor element; a housing having a recess and accommodating the sensor element in the recess; a lead frame connectable to external wiring and to which electrodes of the sensor element are connected; a cover plate disposed opposite the bottom surface of the recess; a port cover having an outside air introduction hole and arranged to cover the cover plate, A sensor characterized in that the cover plate is fixed to the housing or the port cover at multiple locations and is maintained at a predetermined potential by being electrically connected to the lead frame via a connection portion at at least one of the multiple locations.

2. the lead frame has a flat portion on the bottom surface of the recess of the housing on which the sensor element is placed, The sensor according to claim 1 , wherein the cover plate is disposed opposite the flat portion and forms a space surrounding the sensor element together with the flat portion.

3. 3. The sensor according to claim 1, wherein the connection portion has a through hole filled with a conductive material.

4. 4. The sensor according to claim 1, wherein the cover plate is at least partially made of metal and is disposed at a position higher than the surfaces of the sensor element and the lead frame.

5. The sensor described in claim 3, characterized in that the lead frame has an inner lead which is a portion formed inside the housing in a planar view, and an outer lead which is a portion formed outside the housing in a planar view, and the connection portion is located on a line connecting the inner lead and the outer lead in a planar view.

6. The depth of the through hole of the connection part relative to the surface of the inner lead determines the thickness of the cover plate.

6. The sensor according to claim 5, wherein the height of the seat is adjustable.

7. 7. The sensor according to claim 5 or 6, characterized in that the connection is arranged on the lead frame at either GND or VDD.

8. 8. The sensor according to claim 1, wherein a portion other than the connection portion is fixed to the housing at an upper portion of the lead frame via an insulating fixing portion.

9. 9. The sensor according to claim 8, wherein the fixing portion comprises a hole with or without a bottom filled with an insulating material, or a hole with a bottom filled with a conductive material.

10. 10. The sensor according to claim 1, wherein the cover plate is integrally molded with the port cover in such a manner that a flow path is present from the outside air inlet hole to the inside of the housing.

11. 11. The sensor according to claim 1, wherein the cover plate comprises a multi-layer substrate.

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