Package element

Abstract

Provided is a package element in which occurrence of cracks in an internal element and breakage of the internal element can be reduced. The package element comprises: a package; an external electrode provided on an outer surface of the package; an internal element provided inside the package and having a main body and an element electrode provided on a part of an outer surface of the main body and electrically connected to the external electrode; and a coating film interposed between the internal element and the package and covering at least a part of the internal element. At least one of the bonding force between the coating film and the package and the bonding force between the coating film and the main body of the internal element is lower than the bonding force between the package and the main body of the internal element.

Description

Packaged Elements

[0001] The present disclosure relates to packaged devices in which internal components are contained within the package.

[0002] Patent Document 1 discloses, as an example of a package element, a component-embedded substrate in which circuit components corresponding to internal elements are embedded in a resin layer corresponding to the package. In the manufacturing process of the component-embedded substrate, a semi-cured resin sheet is placed on top of the circuit components and pressure-bonded. The pressure-bonded resin sheet fills the gaps between the circuit components. Heat is applied during or after pressure-bonding of the resin sheet. This hardens the resin sheet into a resin layer, and the circuit components and the resin layer are tightly attached to each other.

[0003] Patent No. 5012896

[0004] In the component-embedded substrate disclosed in Patent Document 1, excessive pressure such as that exemplified below may cause cracks or damage to the internal circuitry.

[0005] For example, when a component-embedded substrate is mounted on another external substrate by sintering, the component-embedded substrate may be pressed against the external substrate, and this pressurization may exert pressure on the component-embedded substrate. Furthermore, when a component-embedded substrate is incorporated into a module, the component-embedded substrate may bend, causing a load to act on the component-embedded substrate. Furthermore, when a component-embedded substrate is incorporated into a module, resin molding may be performed on the component-embedded substrate, and this resin molding may cause a load to act on the component-embedded substrate. Furthermore, when wire bonding is performed on the component-embedded substrate, loads or ultrasonic waves may act on the component-embedded substrate during the wire bonding process. Furthermore, when various products incorporating the component-embedded substrate are used or operating, heat, vibration, impact, and the like may act on the component-embedded substrate.

[0006] If the aforementioned pressure, load, ultrasonic waves, heat, vibration, and impact act excessively on the component-embedded substrate, cracks may occur in the internal circuitry or the internal circuitry may be damaged.

[0007] Therefore, an object of the present disclosure is to solve the above-mentioned problems by providing a packaged element that can reduce the occurrence of cracks in the internal element and damage to the internal element.

[0008] A packaged element of one aspect of the present disclosure comprises a package; an external electrode provided on the outer surface of the package; an internal element provided inside the package and having a main body and an element electrode provided on a portion of the outer surface of the main body and electrically connected to the external electrode; and a coating film interposed between the internal element and the package and covering at least a portion of the internal element, wherein at least one of the bonding strength between the coating film and the package and the bonding strength between the coating film and the main body of the internal element is lower than the bonding strength between the package and the main body of the internal element.

[0009] According to the present disclosure, it is possible to provide a packaged element that can reduce the occurrence of cracks in the internal element and damage to the internal element.

[0010] 8 is a side view showing a substrate, a heating element, and a packaged element according to a first embodiment of the present disclosure. 9 is a plan view showing a packaged element according to a first embodiment of the present disclosure. 10 is a bottom view showing a packaged element according to a first embodiment of the present disclosure. 11 is a cross-sectional view showing a cross section taken along line IV-IV in FIG. 2. 12 is an enlarged view of a portion surrounded by a dashed line in FIG. 10. 13 is an enlarged view of a portion surrounded by a dashed line in FIG. 10. 14 is a cross-sectional view showing a packaged element according to a second embodiment of the present disclosure. 15 is a plan view showing a packaged element according to a third embodiment of the present disclosure. 16 is a cross-sectional view showing a cross section taken along line IX-IX in FIG. 11.

[0011] An example of the present disclosure will now be described with reference to the accompanying drawings. The following description is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses. The drawings are schematic, and the dimensional ratios and the like do not necessarily correspond to reality. In the following description, terms indicating specific directions or positions (e.g., terms including "upper," "lower," "right," "left," "front," and "rear") may be used as necessary. The present specification and drawings define the X, Y, and Z directions. The Z direction is the thickness direction of the packaged element, and the X and Y directions are directions perpendicular to the thickness direction of the packaged element. The X and Y directions intersect each other (orthogonal in the present specification and drawings). The use of the terms indicating specific directions or positions described above is intended to facilitate understanding of the present disclosure with reference to the drawings, and the meanings of these terms do not limit the technical scope of the present disclosure.

[0012] First Embodiment A packaged element is provided in, for example, a power module or the like provided in an electric vehicle, a household electrical appliance, or the like. In each embodiment of this specification, the packaged element is a temperature sensor in which a temperature-sensing element for detecting temperature is built into the package. A temperature sensor is an example of a packaged element, and a temperature-sensing element is an example of an internal element. The packaged element is not limited to a temperature sensor, and the internal element is not limited to a temperature-sensing element. For example, the packaged element may be a capacitor element such as a multilayer ceramic capacitor (MLCC), which is an example of an internal element, built into the package, or an inductor element, which is an example of an internal element, built into the package.

[0013] FIG. 1 is a side view showing a substrate, a heating element, and a packaged element according to a first embodiment of the present disclosure. As shown in FIG. 1 , a temperature sensor 10, which is an example of a packaged element, is mounted on a mounting surface 2A of a substrate 2 provided on a power module or the like. A heating element 4 is mounted on the mounting surface 2A of the substrate 2. The heating element 4 is, for example, a semiconductor chip mounted on a power module. The temperature sensor 10 is mounted near the heating element 4. Most of the heat generated by the heating element 4 is transferred to the temperature sensor 10 via the substrate 2. The temperature sensor 10 detects the temperature of the heating element 4. The temperature sensor 10 outputs, for example, information about the temperature that changes in accordance with a change in the temperature of the heating element 4 to the outside via a wire 6 or the like. The information about the temperature of the heating element 4 is, for example, a current value or a voltage value within the temperature sensor 10.

[0014] Fig. 2 is a plan view showing the packaged element according to the first embodiment of the present disclosure, Fig. 3 is a bottom view showing the packaged element according to the first embodiment of the present disclosure, and Fig. 4 is a cross-sectional view showing the cross section IV-IV of Fig. 2.

[0015] As shown in FIGS. 2, 3, and 4, the temperature sensor 10 includes a package 20, a temperature sensitive element 30, an external electrode 40, a second electrode 50, an internal electrode 60, and a coating film 80.

[0016] The package 20 is made of an epoxy resin containing a filler such as silica. The material of the package 20 is not limited to epoxy resin, and may be, for example, urethane.

[0017] The package 20 has one main surface 20A facing one side in the Z direction, another main surface 20B facing the other side in the Z direction, and a side surface 20C as outer surfaces exposed to the outside of the package 20. The side surface 20C connects the one main surface 20A and the other main surface 20B.

[0018] As shown in Figures 2 and 4, an external electrode 40 is provided on one main surface 20A. As shown in Figures 3 and 4, a second-side electrode 50 is provided on the second main surface 20B. The external electrode 40 may be provided on an outer surface of the package 20 other than the first main surface 20A, and the second-side electrode 50 may be provided on an outer surface of the package 20 other than the second main surface 20B. For example, the external electrode 40 may be provided on the side surface 20C, or may be provided across both the first main surface 20A and the side surface 20C.

[0019] As shown in Figures 2 and 4, a temperature sensing element 30 and an internal electrode 60 are provided inside the package 20. As shown in Figure 4, a portion of the internal electrode 60 is exposed on the surface of the package 20, and this exposed portion is in contact with the external electrode 40 in the Z direction. Note that in Figure 2 and Figure 8, which will be described later, portions (e.g., the temperature sensing element 30) that are provided inside the package 20 and cannot be seen from the outside are indicated by dashed lines.

[0020] The external electrode 40, the other-side electrode 50, and the internal electrode 60 are formed by, for example, baking, plating, or sputtering a conductive material. Examples of the conductive material include silver (Ag), palladium (Pd), copper (Cu), nickel (Ni), and gold (Au). In the first embodiment, the bases of the external electrode 40 and the other-side electrode 50 are formed of copper foil and are plated with nickel, palladium, and gold. The internal electrode 60 is plated with copper.

[0021] In the first embodiment, the size of the package 20 is 2 mm in the X direction, 1.25 mm in the Y direction, and 0.85 mm in the Z direction, but is not limited to these sizes.

[0022] 2 and 4 is an electrode for extracting the characteristics from the temperature sensitive element 30. The characteristics of the temperature sensitive element 30 are, for example, a current value that varies depending on the temperature of the temperature sensitive element 30. The characteristics of the temperature sensitive element 30 correspond to information related to temperature that changes with the temperature change of the heating element 4.

[0023] 2 and 4 , in the first embodiment, the temperature sensor 10 has two external electrodes 40. The two external electrodes 40 are a first external electrode 41 and a second external electrode 42. The first external electrode 41 and the second external electrode 42 are arranged side by side along the X direction.

[0024] A conductive wire 6 (see FIG. 1 ) made of aluminum (Al) or the like is electrically connected to each of the first external electrode 41 and the second external electrode 42. As a result, each of the first external electrode 41 and the second external electrode 42 is electrically connected to the outside of the temperature sensor 10 via the wire 6. Note that although one wire 6 is shown in FIG. 1 , in reality, a different wire 6 is connected to each of the first external electrode 41 and the second external electrode 42. In other words, two wires 6 are connected to the temperature sensor 10. In the first embodiment, the diameter of the wire 6 is 300 μm, but the diameter of the wire 6 is not limited to 300 μm.

[0025] When viewed along the Z direction, the outer edge 40A of the external electrode 40 is located inside the outer edge of the one main surface 20A.

[0026] In the first embodiment, the size of the external electrode 40 is 0.8 mm or more in the X direction, 1.0 mm or more in the Y direction, and 0.02 mm in the Z direction. The surface roughness of the external electrode 40 is such that the maximum height (Sz), which is the sum of the maximum peak height (Sp) and the maximum valley depth (Sv), is 15 μm or less.

[0027] The number of external electrodes 40 is not limited to two. Furthermore, the position, size, surface roughness, and shape of the external electrodes 40 are not limited to those shown in Figs. 2 and 4 or described above.

[0028] 3 and 4 is for mounting the temperature sensor 10 on the substrate 2 (see FIG. 1) by solder reflow or the like. In the first embodiment, the other main surface 20B of the temperature sensor 10 is joined to the substrate 2 via the other electrode 50. The other main surface 20B is a surface that faces in the Z direction relative to the mounting surface 2A of the substrate 2 on which the temperature sensor 10 is mounted.

[0029] The means for joining the temperature sensor 10 to the substrate 2 is not limited to solder reflow, and other known means such as sintering may also be used. The temperature sensor 10 does not need to have the other electrode 50. In this case, the temperature sensor 10 can be joined to the substrate 2 by known means such as an adhesive.

[0030] In the first embodiment, the other electrode 50 is electrically insulated from the temperature sensitive element 30 (specifically, the internal element electrode 32 and external element electrode 33 of the temperature sensitive element 30), the external electrode 40, and the internal electrode 60. The other electrode 50 may be electrically connected to at least one of the temperature sensitive element 30, the external electrode 40, and the internal electrode 60.

[0031] As shown in FIG. 3 , in the first embodiment, the temperature sensor 10 has four other-side electrodes 50. The four other-side electrodes 50 are a first other-side electrode 51, a second other-side electrode 52, a third other-side electrode 53, and a fourth other-side electrode 54. The first other-side electrode 51, the second other-side electrode 52, the third other-side electrode 53, and the fourth other-side electrode 54 are arranged two by two in each of the X direction and the Y direction. Note that the number of other-side electrodes 50 is not limited to four. The positions, sizes, and shapes of the other-side electrodes 50 are not limited to those shown in FIGS. 3 and 4 .

[0032] When viewed along the Z direction, the outer edge 50A of the other electrode 50 is located inside the outer edge of the other main surface 20B.

[0033] As shown in Figures 2 and 4, the internal electrode 60 is provided inside the package 20 as described above. As shown in Figure 4, the internal electrode 60 is provided between the temperature sensing element 30 and the external electrode 40 in the Z direction. In the first embodiment, the thickness T of the internal electrode 60 (in other words, the length of the internal electrode 60 in the Z direction) is 20 µm or more. The thickness T may be less than 20 µm. In the first embodiment, the gaps G1 and G2 in the X direction between the inner edge of the internal electrode 60 in the X direction and the inner edge of the external electrode 40 in the X direction are 10 µm or more. The gaps G1 and G2 may be less than 10 µm. The gaps G1 and G2 may be the same value or different values.

[0034] In the first embodiment, the temperature sensor 10 has two internal electrodes 60. The two internal electrodes 60 are a first internal electrode 61 and a second internal electrode 62. The first internal electrode 61 and the second internal electrode 62 are arranged side by side in the X direction. The number of internal electrodes 60 is not limited to two. The position, size, and shape of the internal electrodes 60 are not limited to those shown in FIGS. 2 and 4 .

[0035] As described above, a portion of the internal electrode 60 is exposed on the surface of the package 20, and this exposed portion is covered by and in contact with the external electrode 40 in the Z direction (see FIG. 4 ). As a result, the internal electrode 60 is electrically connected to the external electrode 40. In detail, the first internal electrode 61 is electrically connected to the first external electrode 41, and the second internal electrode 62 is electrically connected to the second external electrode 42.

[0036] 2 , in the first embodiment, the internal electrode 60 is smaller than the external electrode 40 when viewed along the Z direction. Also, in the first embodiment, the outer edge 60A of the internal electrode 60 is located more inward than the outer edge 40A of the external electrode 40 when viewed along the Z direction.

[0037] 2 and 4, as described above, the temperature sensing element 30 is provided inside the package 20. In the first embodiment, the temperature sensing element 30 is a surface-mounted thermistor element.

[0038] 4, the thermosensitive element 30 has a main body 31, four internal element electrodes 32, and two external element electrodes 33. The external element electrodes 33 are an example of element electrodes.

[0039] As shown in FIGS. 2 and 4 , the main body 31 has an outer surface 31A. In the first embodiment, the main body 31 has a rectangular parallelepiped shape, and the outer surface 31A includes a pair of main surfaces 31Aa and 31Ab and four side surfaces 31Ac, 31Ad, 31Ae, and 31Af. The main surface 31Aa faces one side in the Z direction (in other words, toward the one main surface 20A of the package 20). The main surface 31Ab faces the other side in the Z direction (in other words, toward the other main surface 20B of the package 20). The four side surfaces 31Ac, 31Ad, 31Ae, and 31Af connect the main surface 31Aa and the main surface 31Ab. The side surface 31Ac faces one side in the X direction, and the side surface 31Ad faces the other side in the X direction. The side surface 31Ae faces one side in the Y direction, and the side surface 31Af faces the other side in the Y direction. The main body 31 may have a shape other than a rectangular parallelepiped, such as a cylindrical shape.

[0040] The body 31 is made of ceramic metal oxide, which is the material of the thermistor, such as oxides of iron (Fe), cobalt (Co), nickel (Ni), and manganese (Mn).

[0041] The internal element electrodes 32 and the external element electrodes 33 are made of materials such as silver (Ag), palladium (Pd), and copper (Cu).

[0042] As shown in Fig. 4, four internal element electrodes 32 are provided inside the main body 31. Each internal element electrode 32 is rectangular and plate-shaped when viewed along the Z direction. The four internal element electrodes 32 are arranged side by side at intervals in the Z direction. The four internal element electrodes 32 are arranged parallel or approximately parallel to each other. In the first embodiment, the intervals between the internal element electrodes 32 are equal, but may be different.

[0043] In the first embodiment, the four internal element electrodes 32 include two first internal element electrodes 321 and two second internal element electrodes 322. Note that the number of internal element electrodes 32 included in the temperature sensing element 30 is not limited to four.

[0044] The first internal element electrodes 321 and the second internal element electrodes 322 are arranged alternately in the Z direction. The first internal element electrodes 321 are arranged closer to one side in the X direction inside the main body 31. The second internal element electrodes 322 are arranged closer to the other side in the X direction inside the main body 31.

[0045] In the first embodiment, the two external element electrodes 33 include one first external element electrode 331 and one second external element electrode 332. Note that the number of external element electrodes 33 included in the temperature sensing element 30 is not limited to two.

[0046] Each of the two first internal element electrodes 321 penetrates the coating film 80 and is electrically connected to the first external element electrode 331. Each of the two second internal element electrodes 322 penetrates the coating film 80 and is electrically connected to the second external element electrode 332.

[0047] Each of the two external element electrodes 33 is provided on a part of the outer surface 31A of the main body 31. In the first embodiment, the first external element electrode 331 covers the entire side surface 31Ac and the ends of the principal surface 31Aa, the principal surface 31Ab, the side surface 31Ae, and the side surface 31Af on the side of the side surface 31Ac in the X direction. The second external element electrode 332 covers the entire side surface 31Ad and the ends of the principal surface 31Aa, the principal surface 31Ab, the side surface 31Ae, and the side surface 31Af on the side of the side surface 31Ad in the X direction.

[0048] The first external element electrode 331 is metal-bonded to the first internal electrode 61 via a bonding material 34 such as solder or a conductive adhesive. The second external element electrode 332 is metal-bonded to the second internal electrode 62 via a bonding material 35 such as solder or a conductive adhesive. As a result, the temperature sensing element 30 is mounted on the internal electrode 60 and is electrically connected to the internal electrode 60.

[0049] The first external element electrode 331 is electrically connected to the first external electrode 41 via the first internal electrode 61, and the second external element electrode 332 is electrically connected to the second external electrode 42 via the second internal electrode 62. In other words, the first external element electrode 331, which is one of the two external element electrodes 33, is electrically connected to the first external electrode 41, which is one of the two external electrodes 40. Furthermore, the second external element electrode 332, which is the other of the two external element electrodes 33, is electrically connected to the second external electrode 42, which is the other of the two external electrodes 40.

[0050] As described above, the internal element electrode 32 and the external element electrode 33 of the temperature sensitive element 30 are electrically connected to the external electrode 40 .

[0051] As a result, the current flowing through the temperature sensor 30 is output from the external electrode 40 via the wire 6 (see FIG. 1) to the outside of the temperature sensor 10. The temperature inside the temperature sensor 30 is detected according to the value of this current. For example, if the temperature sensor 30 is an NTC thermistor (negative temperature coefficient thermistor), the resistance of the temperature sensor 30 decreases as the temperature inside the temperature sensor 30 increases, resulting in a higher current being output to the outside. When the temperature inside the temperature sensor 30 increases due to the heat generated by the heating element 4 (see FIG. 1) being transferred to the temperature sensor 30 of the temperature sensor 10, the current output to the outside of the temperature sensor 10 increases.

[0052] When the temperature-sensing element 30 is a thermistor element, the temperature-sensing element 30 is not limited to an NTC thermistor, but may be, for example, a PTC thermistor (positive temperature coefficient thermistor). The temperature-sensing element 30 is not limited to a thermistor element as long as it is an element that can detect temperature by changing its characteristics in response to temperature. For example, the temperature-sensing element 30 may be a platinum-side temperature resistor (a so-called Pt sensor).

[0053] The distance D1 in the Z direction from the other side position of the temperature sensing element 30 closest to the other main surface 20B in the Z direction to the other main surface 20B is longer than the distance D2 in the Z direction from the other side position to the one main surface 20A.

[0054] For example, the distance D1 is designed to be 40 μm or more, and the volume resistivity between the other main surface 20B of the package 20 and the temperature sensitive element 30 is 0.1×10 １１ By combining the design of the distance D1 and the volume resistivity, a dielectric strength of 3.5 KV or more can be obtained.

[0055] The coating film 80 is interposed between the temperature sensitive element 30 and the package 20. In the first embodiment, the coating film 80 covers the entire outer surface 31A of the body 31 of the temperature sensitive element 30. The coating film 80 is in contact with the temperature sensitive element 30 and the package 20.

[0056] In the first embodiment, the coating film 80 is made of silica, but is not limited to silica. The coating film 80 may be made of a material other than silica, provided that the coating film 80 satisfies the bonding strength conditions described below. For example, the coating film 80 may be made of alumina.

[0057] The bonding strength between the coating film 80 and the package 20 is lower than the bonding strength between the package 20 and the body 31 of the temperature sensitive element 30. The bonding strength between the coating film 80 and the package 20 is the bonding strength at the interface between the coating film 80 and the package 20, which are in contact with each other. On the other hand, in the first embodiment, as described above, the coating film 80 completely covers the temperature sensitive element 30, so the package 20 and the temperature sensitive element 30 are not in contact with each other. Therefore, the bonding strength between the coating film 80 and the body 31 of the temperature sensitive element 30 is the bonding strength at the interface between the coating film 80 and the body 31 in the case where the coating film 80 and the body 31 are in contact with each other.

[0058] The aforementioned bonding strength is determined by various factors, such as the chemical bonding state of the two components (e.g., the coating film 80 and the package 20) that are in contact with each other and the surface roughness at the interface between the two components. For example, if the aforementioned chemical bonding state is strong, the bonding strength will be strong. Also, for example, if the aforementioned surface roughness at the interface is small (in other words, if the interface is smooth), the bonding strength will be weak. In the first embodiment, the arithmetic surface roughness Ra of the coating film 80 is approximately 0.025 μm. On the other hand, the arithmetic surface roughness Ra of the body 31 of the temperature sensing element 30 without the coating film 80 is approximately 0.2 μm.

[0059] The bonding strength between the coating film 80 and the package 20 is lower than the bonding strength between the package 20 and the body 31 of the temperature sensitive element 30, but is not limited to this. For example, the bonding strength between the coating film 80 and the body 31 of the temperature sensitive element 30 may be lower than the bonding strength between the package 20 and the body 31 of the temperature sensitive element 30. Of course, both the bonding strength between the coating film 80 and the package 20 and the bonding strength between the coating film 80 and the body 31 of the temperature sensitive element 30 may be lower than the bonding strength between the package 20 and the body 31 of the temperature sensitive element 30.

[0060] The temperature sensor 10 according to the first embodiment can achieve the following effects.

[0061] In a configuration in which the package 20 and the temperature-sensing element 30 are in contact with each other, when an external force or the like acts on the package 20, stress from the package 20 to the temperature-sensing element 30 may cause cracks in the temperature-sensing element 30 or damage to the temperature-sensing element 30.

[0062] According to the first embodiment, at least one of the bonding strength between the coating film 80 and the package 20 and the bonding strength between the coating film 80 and the body 31 of the temperature sensitive element 30 is weaker than the bonding strength between the package 20 and the temperature sensitive element 30 .

[0063] Therefore, when an external force or the like is applied to the package 20, the package 20 and the coating film 80 are likely to peel off from each other, and the coating film 80 and the temperature sensitive element 30 are likely to peel off from each other. This creates gaps between the package 20 and the coating film 80, and between the coating film 80 and the temperature sensitive element 30. These gaps buffer the action of stress from the package 20 to the temperature sensitive element 30. As a result, the occurrence of cracks in the temperature sensitive element 30 and damage to the temperature sensitive element 30 can be reduced.

[0064] According to the first embodiment, the coating film 80 covers the entire outer surface 31A of the body 31 of the temperature sensitive device 30. Therefore, the coating film 80 can buffer the action of stress on the temperature sensitive device 30 from all directions.

[0065] According to the first embodiment, because there is no electrical connection between the temperature sensor 30 and the other main surface 20B, it is easy to configure the temperature sensor 10 so that the temperature sensor 30 is located near the one main surface 20A and away from the other main surface 20B. This allows the length of the package 20 in the Z direction between the temperature sensor 30 and the mounting surface 2A to be increased when the other main surface 20B of the package 20 is mounted on the mounting surface 2A. This longer length makes it more difficult for external forces acting on the temperature sensor 10 from the mounting surface 2A to reach the temperature sensor 30. This reduces the occurrence of cracks in the temperature sensor 30 and damage to the temperature sensor 30.

[0066] According to the first embodiment, the other electrode 50 can be used as a mounting electrode when mounting the temperature sensor 10 on the mounting surface 2A. This allows the temperature sensor 10 and the mounting surface 2A to be easily joined by various means such as solder reflow or sintering.

[0067] <Modification of First Embodiment> In the above-described embodiment, the coating film 80 covers the entire outer surface 31A of the body 31 of the temperature sensitive element 30. However, the coating film 80 may cover only a part of the outer surface 31A of the body 31 of the temperature sensitive element 30.

[0068] For example, the coating film 80 may cover only the portions of the outer surface 31A of the body 31 of the temperature sensitive element 30 where the external element electrodes 33 are not provided. In the configuration shown in Fig. 4, the portions of the outer surface 31A where the external element electrodes 33 are not provided are the portions of each of the main surface 31Aa, the main surface 31Ab, the side surface 31Ae, and the side surface 31Af excluding both end portions in the X direction. The coating film 80 may cover the entire portions, or may cover only a portion of the portions. Furthermore, the coating film 80 may cover other portions in addition to the portions.

[0069] In the portions of the outer surface 31A of the body 31 of the temperature sensitive element 30 where the external element electrodes 33 are provided, the action of stress from the package 20 on the body 31 of the temperature sensitive element 30 is reduced by the presence of the external element electrodes 33. According to this modification, the coating film 80 covers the portions of the outer surface 31A of the body 31 of the temperature sensitive element 30 where the external element electrodes 33 are not provided. As a result, even in the portions where the action of the stress cannot be reduced due to the absence of the external element electrodes 33, the action of stress from the package 20 on the temperature sensitive element 30 can be buffered by the presence of the coating film 80.

[0070] Furthermore, for example, the coating film 80 may cover only the side surfaces 31Ac, 31Ad, 31Ae, and 31Af. In other words, the coating film 80 does not have to cover the pair of main surfaces 31Aa and 31Ab.

[0071] For example, when the temperature sensor 10 is mounted on the substrate 2 by sintering, the temperature sensor 10 is pressed in the Z direction toward the substrate 2. In this case, the temperature sensor 10 tends to expand in a lateral direction (e.g., the X direction or the Y direction) intersecting the Z direction. According to this modification, the side surfaces 31Ac, 31Ad, 31Ae, and 31Af of the outer surface 31A of the body 31 of the temperature sensor 30, which face the lateral direction, are covered with the coating film 80. Therefore, the force of expansion in the lateral direction easily causes the package 20 and the coating film 80 to peel away from each other, and the coating film 80 and the temperature sensor 30 to peel away from each other. In other words, according to this modification, the effect of buffering the action of stress from the package 20 on the side surfaces 31Ac, 31Ad, 31Ae, and 31Af of the temperature sensor 30 can be improved.

[0072] In the first embodiment, the coating film 80 is in contact with the temperature sensitive element 30 and the package 20. However, at least a portion of the coating film 80 may be separated from the temperature sensitive element 30 and the package 20.

[0073] Fig. 5 is an enlarged view of the portion surrounded by the dashed line in Fig. 4. In Figs. 4 and 5, the dashed line surrounding this portion is denoted by reference numeral 91. As shown in Fig. 5, a gap G3 may be provided in at least a portion between the coating film 80 and the package 20.

[0074] The gap G3 may be provided in a portion between the coating film 80 and the package 20. In this case, the coating film 80 and the package 20 are in contact with each other in a portion and are separated from each other in the remaining portion. For example, the portions where the coating film 80 and the package 20 are separated from each other may be provided sparsely.

[0075] The gap G3 may be provided over the entire space between the coating film 80 and the package 20. In this case, the coating film 80 and the package 20 are separated from each other and are not in contact with each other.

[0076] According to this modification, the gap G3 provided in at least a part between the coating film 80 and the package 20 can buffer the action of stress from the package 20 to the temperature sensitive element 30 .

[0077] Figure 6 is an enlarged view of the portion surrounded by the dashed line in Figure 4. In Figures 4 and 6, the dashed line surrounding this portion is given the reference numeral 92. As shown in Figure 6, a gap G4 may be provided between the coating film 80 and the main body 31 of the temperature sensitive element 30.

[0078] The gap G4 may be provided in a portion between the coating film 80 and the body 31 of the temperature sensitive device 30. In this case, the coating film 80 and the body 31 of the temperature sensitive device 30 are in contact with each other in a portion, and are separated from each other in the remaining portion. For example, the portions where the coating film 80 and the body 31 of the temperature sensitive device 30 are separated from each other may be provided sparsely.

[0079] The gap G4 may be provided throughout the entire space between the coating film 80 and the body 31 of the temperature sensitive device 30. In this case, the coating film 80 and the body 31 of the temperature sensitive device 30 are separated from each other and are not in contact with each other.

[0080] According to this modification, the gap G4 provided in at least a portion between the coating film 80 and the body 31 of the temperature sensitive element 30 can buffer the action of stress from the package 20 to the temperature sensitive element 30 .

[0081] <Manufacturing Method> A manufacturing method for the temperature sensitive element 30 and the temperature sensor 10 will be described below.

[0082] In the first step, the temperature sensing element 30 is manufactured. In the second step, the temperature sensor 10 is manufactured. Both the temperature sensing element 30 and the temperature sensor 10 are manufactured by known methods.

[0083] A method for manufacturing the temperature sensitive element 30 will be described below. Note that the following manufacturing method is an example.

[0084] First, the main body 31 is prepared. Specifically, the internal element electrodes 32 are formed on ceramic sheets by printing, and then a plurality of these ceramic sheets are stacked and pressure-bonded to form an unfired ceramic laminate. The ceramic laminate is then cut into individual pieces and fired to form the main body 31.

[0085] Next, the coating film 80 formation process is carried out. This will be described in detail below. A solvent and a catalyst are placed in a container and then stirred. In this embodiment, 2-propanol is used as the solvent, and aqueous ammonia is used as the catalyst. The aqueous ammonia functions as a catalyst that promotes the hydrolysis of tetraethyl orthosilicate, which will be described later. Next, one or more main bodies 31 are placed in the container. Next, tetraethyl orthosilicate is placed and stirred. This causes the tetraethyl orthosilicate to hydrolyze, and the hydrolyzed tetraethyl orthosilicate adheres to the outer surface 31A of the main body 31. As a result, the coating film 80 is formed. Thereafter, the main body 31 on which the coating film 80 has been formed is dried.

[0086] Next, an application process is performed to apply the external element electrodes 33. Conductive paste is applied to the entire surface of the side surface 31Ac of the main body 31, on which the coating film 80 has been formed on the outer surface 31A, and to the ends of the principal surface 31Aa, the principal surface 31Ab, the side surface 31Ae, and the side surface 31Af on the side surface 31Ac side in the X direction, to form the first external element electrodes 331. Conductive paste is also applied to the entire surface of the side surface 31Ad of the main body 31 and to the ends of the principal surface 31Aa, the principal surface 31Ab, the side surface 31Ae, and the side surface 31Af on the side surface 31Ad side in the X direction, to form the second external element electrodes 332. Of course, the first external element electrodes 331 and the second external element electrodes 332 may be formed by applying conductive paste to the entire outer surface of the package 20 and then removing unnecessary portions by etching or the like.

[0087] Next, a curing process is carried out in which the coating film 80 is formed on the outer surface 31A and the main body 31 to which the external element electrodes 33 are applied is cured. Specifically, the main body 31 after the application process is carried out is heated. This causes the coating film 80 to be baked and cured. This also causes the external element electrodes 33 to be baked.

[0088] In this embodiment, during heating in the curing process, the Kirkendall effect, which arises from the difference in diffusion rate between the internal element electrode 32 and the external element electrode 33, causes the silver contained in the internal element electrode 32 to be attracted to the external element electrode 33 containing palladium. As a result, the internal element electrode 32 extends through the coating film 80, and the internal element electrode 32 and the external element electrode 33 are connected to each other.

[0089] In this manner, the temperature sensitive element 30 is manufactured.

[0090] The following describes a method for manufacturing the temperature sensor 10. Note that the following manufacturing method is an example.

[0091] First, an internal electrode 60 is formed on the first metal foil. A film resist is applied to one main surface of the first metal foil, and the desired opening is formed by general exposure and development processes. A metal plating layer is formed in the opening by plating, and the resist is removed to form a partial convex portion on one main surface of the first metal foil. This convex portion is the electrode formation region, and becomes the internal electrode 60 through the process described below.

[0092] Next, a paste of bonding materials 34 and 35 is applied onto the electrode formation regions.

[0093] Next, the temperature sensitive element 30 is mounted on the electrode formation area to which the paste of the bonding materials 34, 35 has been applied by a known method such as reflow.

[0094] Next, a resin sheet, which will be the material for the package 20, is laminated on one main surface of the first metal foil. The resin sheet is a semi-cured (e.g., B-stage) sheet containing, for example, an inorganic filler and a thermosetting resin. As a result, the temperature-sensitive element 30 is covered by the package 20. The package 20 also fits into the recessed portion of one main surface of the first metal foil. A second metal foil is also laminated on top of the package 20. As a result, the package 20 is sandwiched between the first metal foil and the second metal foil. The laminated package 20, first metal foil, and second metal foil are pressure-bonded and then thermally cured.

[0095] Next, the first metal foil and the second metal foil are etched to form the external electrode 40 and the other-side electrode 50, respectively. Specifically, a film resist is applied to both sides, and then exposure, development, etching, and resist removal processes are performed. A plated metal coating of nickel (Ni), gold (Au), or the like is formed on the external electrode 40 and the other-side electrode 50 as needed.

[0096] In this manner, the temperature sensor 10 is manufactured.

[0097] Second Embodiment The temperature sensor may have any configuration as long as it includes a package 20, an external electrode 40 provided on the outer surface of the package 20, an internal element such as a temperature sensing element 30 provided inside the package 20, and a coating film 80 interposed between the internal element and the package 20. In other words, the temperature sensor is not limited to the configurations shown in Figures 2, 3, and 4, etc., provided that it has the above configuration. For example, the temperature sensor may have a configuration as shown in Figure 7.

[0098] 7 is a cross-sectional view showing a packaged element according to a second embodiment of the present disclosure. A temperature sensor 10A, which is an example of a packaged element according to the second embodiment, differs from the temperature sensor 10 according to the first embodiment in that the external electrodes 40 are provided on the other main surface 20B. Differences from the first embodiment will be described below. Components common to the temperature sensor 10 according to the first embodiment are denoted by the same reference numerals, and their description will be omitted in principle, and will be described only when necessary.

[0099] 7, in the temperature sensor 10A, the external electrode 40 is provided on the other main surface 20B. Therefore, in the temperature sensor 10A, the temperature sensing element 30 is provided in a position close to the other main surface 20B. In contrast, in the temperature sensor 10 according to the first embodiment described above, the temperature sensing element 30 is provided in a position close to the one main surface 20A.

[0100] Furthermore, the temperature sensor 10A does not have the other-side electrode 50. In the second embodiment, the external electrode 40 serves as a mounting electrode when the temperature sensor 10A is mounted on the mounting surface 2A.

[0101] Furthermore, the temperature sensor 10A does not have an electrode on the one main surface 20A. However, the temperature sensor 10A may have an electrode on the one main surface 20A. In this case, the temperature sensing element 30 may be electrically connected to the electrode. For example, the internal member 70 (see FIG. 9 ) described in the third embodiment may penetrate the package 20 in the Z direction and be connected to both the electrode provided on the one main surface 20A and the external electrode 40 provided on the other main surface 20B. In this case, the external element electrode 33 of the temperature sensing element 30 is electrically connected to the electrode provided on the one main surface 20A via the external electrode 40 and the internal member 70. A wire 6 or the like can be connected to the electrode.

[0102] Third Embodiment Fig. 8 is a plan view showing a package element according to a third embodiment of the present disclosure. Fig. 9 is a cross-sectional view showing a cross section taken along line IX-IX in Fig. 8. A temperature sensor 10B, which is an example of a package element according to the third embodiment, differs from the temperature sensor 10 according to the first embodiment in that it includes an internal member 70. Differences from the first embodiment will be described below. Components in common with the temperature sensor 10 according to the first embodiment are denoted by the same reference numerals, and their description will be omitted in principle, and will be described only when necessary.

[0103] 8 and 9, the temperature sensor 10B includes one or more internal members 70. The internal members 70 are provided inside the package 20. The internal members 70 are made of a material that is harder than the package 20. In other words, the internal members 70 are made of a material that has a greater modulus of elasticity than the package 20.

[0104] In the third embodiment, the temperature sensor 10B includes four internal members 70. The four internal members 70 are provided near the temperature sensing element 30 in a direction perpendicular to the Z direction. The four internal members 70 are provided two on each side of the temperature sensing element 30 in the Y direction. The internal members 70 are cylindrical and made of metal such as copper (Cu), copper nitride (Cu3N), a copper-tin alloy (Cu-Sn), phosphor bronze, a copper-magnesium-zinc alloy, a copper-nickel alloy (Cu-Ni), and a copper-iron alloy (Cu-Fe).

[0105] The shape, size, and position of the internal member 70 are not limited to those shown in Figures 8 and 9. Although the four internal members 70 have the same shape and size in Figures 8 and 9, they may have different shapes and sizes. The internal members 70 may be made of metal only, or may contain metal in part. The internal members 70 may also be made of a material other than metal, such as ceramic.

[0106] In the third embodiment, the internal member 70 is electrically connected to the external electrode 40, but may be electrically insulated from the external electrode 40. In the third embodiment, the internal member 70 is electrically insulated from the other-side electrode 50 and the internal electrode 60, but may be electrically connected to these electrodes.

[0107] The temperature sensor 10B according to the third embodiment can achieve the following effects.

[0108] According to the third embodiment, the effect of an external force acting on the temperature sensor 10B on the temperature sensitive element 30 can be reduced by the presence of the internal member 70.

[0109] According to the third embodiment, since the internal member 70 is made of metal, when the temperature sensing element 30 is an element that detects temperature, such as a thermistor, it is possible to improve the transfer of heat from the outside of the temperature sensor 10B to the temperature sensing element 30. This improves the detection accuracy of the temperature sensing element 30.

[0110] According to the third embodiment, the internal member 70 can be used to electrically connect the external element electrode 33 and the external electrode 40 of the temperature sensitive element 30. There is also an advantage in terms of manufacturing that the same material as the bonding materials 34, 35 used to mount the temperature sensitive element 30 can be used to bond the internal member 70 and the external electrode 40.

[0111] The package element described above can also be expressed as follows.

[0112] (1) A package element according to one aspect of the present disclosure comprises: a package; an external electrode provided on an outer surface of the package; an internal element provided inside the package, the internal element having a main body and an element electrode provided on a portion of the outer surface of the main body and electrically connected to the external electrode; and a coating film interposed between the internal element and the package and covering at least a portion of the internal element, wherein at least one of the bonding strength between the coating film and the package and the bonding strength between the coating film and the main body of the internal element is lower than the bonding strength between the package and the main body of the internal element.

[0113] (2) In the packaged element of (1), the coating film may cover the entire outer surface of the main body of the internal element.

[0114] (3) In the packaged element of (1), the coating film may cover a portion of the outer surface of the main body of the internal element where the element electrodes are not provided.

[0115] (4) In the package element of (1), the outer surface of the main body of the internal element may have a pair of main surfaces facing one side and the other side in the thickness direction of the package, and side surfaces connecting the pair of main surfaces, and the coating film may cover the side surfaces.

[0116] (5) In the packaged element of any one of (1) to (4), a gap may be provided at least partially between the coating film and the package.

[0117] (6) In the package element of any one of (1) to (5), a gap may be provided at least partially between the coating film and the main body of the internal element.

[0118] (7) In any one of the package elements (1) to (6), the outer surface of the package may have one main surface facing one side in the thickness direction and another main surface facing the other side in the thickness direction, the external electrode may be provided on the one main surface and electrically connected to a conductive wire, and the other main surface may be a surface facing a mounting surface on which the package element is mounted.

[0119] (8) The package element of (7) may further include a second electrode provided on the second main surface and electrically insulated from the external electrode and the element electrode.

[0120] (9) The package element of any one of (1) to (8) may further include an internal member provided inside the package and made of a material having a greater modulus of elasticity than the package.

[0121] (10) In the packaged element of (9), the internal member may be made of metal.

[0122] (11) In the packaged element of (10), the internal member may be electrically connected to the external electrode.

[0123] (12) In any one of the package elements (1) to (11), two of the external electrodes may be provided on the outer surface of the package, the internal element may have two of the element electrodes, one of the two external electrodes may be electrically connected to one of the two element electrodes, and the other of the two external electrodes may be electrically connected to the other of the two element electrodes.

[0124] Any of the various embodiments described above may be combined appropriately to achieve the effects of each of them.

[0125] While the present invention has been fully described in connection with preferred embodiments, with appropriate reference to the drawings, various changes and modifications will become apparent to those skilled in the art, and it is to be understood that such changes and modifications are included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

[0126] 2A Mounting surface 6 Wire 10 Temperature sensor 20 Package 20A One main surface 20B Other main surface 30 Temperature sensing element 31 Main body 31A Outer surface 31Aa Main surface 31Ab Main surface 31Ac Side surface 31Ad Side surface 31Ae Side surface 31Af Side surface 33 External element electrode 40 External electrode 50 Other side electrode 70 Internal member 80 Coating film

Claims

1. A packaged element comprising: a package; an external electrode provided on the outer surface of the package; an internal element provided inside the package and having a main body and an element electrode provided on a portion of the outer surface of the main body and electrically connected to the external electrode; and a coating film interposed between the internal element and the package and covering at least a portion of the internal element, wherein at least one of the bonding strength between the coating film and the package and the bonding strength between the coating film and the main body of the internal element is lower than the bonding strength between the package and the main body of the internal element.

2. The packaged element of claim 1, wherein said coating film covers all of the outer surface of said body of said internal element.

3. The packaged element according to claim 1, wherein the coating film covers a portion of the outer surface of the body of the internal element on which the element electrodes are not provided.

4. The package element according to claim 1, wherein the outer surface of the main body of the internal element has a pair of main surfaces facing one side and the other in the thickness direction of the package, and a side surface connecting the pair of main surfaces, and the coating film covers the side surface.

5. The packaged element according to any one of claims 1 to 4, wherein a gap is provided at least partially between the coating film and the package.

6. The packaged element according to any one of claims 1 to 5, wherein a gap is provided at least partially between the coating film and the body of the internal element.

7. A package element according to any one of claims 1 to 6, wherein the outer surface of the package has one main surface facing one side in the thickness direction and another main surface facing the other side in the thickness direction, the external electrodes are provided on the one main surface and electrically connected to conductive wires, and the other main surface is a surface facing a mounting surface on which the package element is mounted.

8. The packaged element according to claim 7, further comprising an other-side electrode provided on the other main surface and electrically insulated from the external electrode and the element electrode.

9. A packaged element according to any one of claims 1 to 8, further comprising an internal member disposed within the package and constructed of a material having a greater modulus of elasticity than the package.

10. The packaged element of claim 9, wherein said inner member is constructed of metal.

11. The packaged element of claim 10, wherein the internal member is electrically connected to the external electrode.

12. A packaged element according to any one of claims 1 to 11, wherein two external electrodes are provided on the outer surface of the package, the internal element has two of the element electrodes, one of the two external electrodes is electrically connected to one of the two element electrodes, and the other of the two external electrodes is electrically connected to the other of the two element electrodes.

Images