Temperature sensor and method for manufacturing the same

Abstract

To provide a temperature sensor which has better responsibility than a conventional temperature sensor without lowering strength.SOLUTION: A temperature sensor 1 has a pair of lead frames 3, a thermistor 5 provided on the pair of lead frames 3, a first resin part 7 which is composed of an epoxy resin, and covers the thermistor 5 and a part in the vicinity of the thermistor 5 of the pair of lead frames 3 with predetermined rigidity, and a second resin part 9 which covers a part of the first resin part 7 and a part of the pair of lead frames 3 so as to expose the part in the vicinity of the thermistor 5 out of the first resin part 7. As for the temperature sensor 1, there is the case where a width of a part of the lead frame 3 is narrowed, and a quantity of heat flowing through the lead frame 3 is decreased.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a temperature sensor and a method for manufacturing a temperature sensor. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is known a temperature sensor in which a temperature detection element (thermistor) and lead wires are coated with epoxy resin, which has excellent heat resistance and chemical resistance (see Patent Document 1).

[0003] Also, a temperature sensor has been known in the past in which a lead wire portion is connected to a heat-sensitive element (thermistor), and the two are sealed with a sealing layer, the sealing layer is connected to a resin base, and a heat transfer agent is provided in the gap between the sealing layer and the resin base (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-67493 [Patent Document 2] JP 2001-141573 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in the temperature sensor described in Patent Document 1, the temperature detection element (thermistor) and lead wires are protected by a coating of epoxy resin. However, the coating makes the epoxy resin thinner, and the outer shape of the epoxy resin conforms to the outer shapes of the thermistor and lead wires. In other words, the outer shape of the epoxy resin is slightly larger than the outer shapes of the thermistor and lead wires.

[0006] In the temperature sensor described in Patent Document 1, the thickness of the epoxy resin coating is thin, so the strength of the temperature sensor is low. In the temperature sensor described in Patent Document 2, the thermistor detects the heat that has flowed through three layers, the resin base, the heat transfer agent, and the sealing layer, so the response is poor.

[0007] An object of the present invention is to provide a temperature sensor having better response than conventional temperature sensors without reducing strength. [Means for solving the problem]

[0008] A temperature sensor according to one embodiment of the present invention includes a pair of lead frames, a thermistor provided on the pair of lead frames, and an epoxy resin, and includes a first resin portion covering the thermistor and a portion of the pair of lead frames near the thermistor with a predetermined rigidity, and a second resin portion covering a portion of the first resin portion and a portion of the pair of lead frames such that the portion of the first resin portion near the thermistor is exposed.

[0009] Furthermore, a method of manufacturing a temperature sensor according to this aspect of the present invention includes a thermistor installation step of installing a thermistor on a pair of lead frames, a first resin part installation step of providing a first resin part having a predetermined rigidity by covering the thermistor and portions of the pair of lead frames near the thermistor with epoxy resin by transfer molding after installing the thermistor on the pair of lead frames in the thermistor installation step, and a second resin part installation step of providing a first resin part in the first resin part installation step, by insert molding, so as to cover a portion of the first resin part and a portion of the pair of lead frames so that the portion of the first resin part near the thermistor is exposed. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a temperature sensor according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view of part II in FIG. 1, taken along a plane perpendicular to the vertical direction and located at the thermistor. [Diagram 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along the line IV-IV in FIG. [Diagram 5] 5A to 5C are diagrams illustrating a manufacturing process of a temperature sensor according to an embodiment of the present invention. [Figure 6] 5A to 5C are diagrams illustrating a manufacturing process of a temperature sensor according to an embodiment of the present invention. [Figure 7] FIG. 13 is a diagram showing a temperature sensor according to a comparative example. [Figure 8] FIG. 13 is a diagram showing a temperature sensor according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A temperature sensor 1 according to an embodiment of the present invention is installed in a mounting partner (not shown) for use, and measures the temperature of a fluid such as LLC (long life coolant). As shown in Figures 1 to 4, the temperature sensor 1 is configured to include a pair of lead frames 3, a thermistor 5, a first resin part 7, and a second resin part 9.

[0012] Here, for ease of explanation, a predetermined direction in the temperature sensor 1 is defined as the vertical direction, a predetermined direction perpendicular to the vertical direction is defined as the horizontal direction, and a direction perpendicular to the vertical and horizontal directions is defined as the height direction. Moreover, one end side in the vertical direction is defined as the first end side, and the other end side in the vertical direction is defined as the second end side. One end side in the horizontal direction is defined as the first end side, and the other end side in the horizontal direction is defined as the second end side. Furthermore, one end side in the height direction is defined as the upper side, and the other end side in the height direction is defined as the lower side.

[0013] The pair of lead frames 3 are made of a conductive material such as metal, each of which is elongated in the height direction and arranged side by side at a predetermined interval. The thermistor 5 is provided on the pair of lead frames 3 at the lower end of the pair of lead frames 3 in the height direction.

[0014] The thermistor 5 has a first end, which is one end thereof, mechanically and electrically joined to a first lead frame 3A, which is one of the pair of lead frames 3. The thermistor 5 has a second end, which is the other end thereof, mechanically and electrically joined to a second lead frame 3B, which is the other of the pair of lead frames 3.

[0015] The first resin portion 7 is made of an insulating epoxy resin and covers the thermistor 5 and the portions of the pair of lead frames 3 near the thermistor 5 (lower portions) with a predetermined rigidity while being in direct contact with the thermistor 5 and the pair of lead frames 3.

[0016] Epoxy resin is used to facilitate transfer molding of the first resin portion 7. Transfer molding makes it possible to obtain the first resin portion 7 with good shape accuracy, and to ensure that the position and posture of the pair of lead frames 3 relative to the first resin portion 7 are accurate.

[0017] The epoxy resin forming the first resin portion 7 has a high thermal conductivity of approximately 0.8 W / m·K. The thermal conductivity of the epoxy resin may be between 0.3 W / m·K and 2.0 W / m·K. Furthermore, the thermal conductivity of the first resin portion 7 is greater than that of the second resin portion 9.

[0018] The first resin portion 7 is not a thin film, but has a predetermined thickness, covering the thermistor 5 and the portions of the pair of lead frames 3 near the thermistor 5. This provides the first resin portion 7 with sufficient rigidity to maintain a predetermined shape even if the lead frames 3 and thermistor 5 are not present. More specifically, the rigidity of the first resin portion 7 is such that even if a person applies force to the first resin portion 7 with a finger, the deformation is hardly noticeable to the naked eye.

[0019] The second resin part 9 is made of a synthetic resin that is resistant to hydrolysis and has chemical resistance and toughness. For example, the second resin part 9 is made of syndiotactic polystyrene resin (SPS resin). The thermal conductivity of SPS resin is about 0.27 W / m K.

[0020] The second resin portion 9 covers a part of the first resin portion 7 and a part of the pair of lead frames 3 such that a portion of the first resin portion 7 near the thermistor 5 is exposed. That is, the second resin portion 9 is in direct contact with a part (upper end portion in the height direction) of the first resin portion 7 (epoxy resin) and a part (middle portion in the height direction) of the pair of lead frames 3, and is provided on the first resin portion 7 and the pair of lead frames 3. The second resin portion 9 has insulating properties and, like the first resin portion 7, has a predetermined rigidity.

[0021] The second resin part 9 is provided so that the ends (upper ends) of the pair of lead frames 3 opposite the thermistor 5 are exposed. The second resin part 9 is provided for mounting the temperature sensor 1 on a mating part of the temperature sensor 1. The second resin part 9 is provided for connecting a connector (not shown) to the exposed ends (upper ends) of the pair of lead frames 3.

[0022] To explain further, as described above, the pair of lead frames 3 extend in the height direction, slightly spaced apart and parallel to each other. The thermistor 5 is provided at the lower ends of the pair of lead frames 3 in the height direction. The first resin portion 7 is provided at the lower ends of the pair of lead frames 3 and thermistor 5 in the height direction. The first resin portion 7 covers the pair of lead frames 3 and thermistor 5.

[0023] The second resin portion 9 is provided at an upper end of the first resin portion 7 and at a middle portion in the height direction of the pair of lead frames 3. The second resin portion 9 covers the first resin portion 7 and the lead frame 3 such that a portion of the first resin portion 7 near the thermistor 5 (the lower end and middle portion of the first resin portion 7 in the height direction) is exposed. The lower end of the second resin portion 9 is located above the thermistor 5 in the height direction.

[0024] The upper ends of the pair of lead frames 3 in the height direction are not covered with the first resin portion 7 and the second resin portion 9 and are exposed.

[0025] The temperature sensor 1 is also provided with a potting material 13. The potting material 13 is provided at the boundary between the first resin portion 7 and the second resin portion 9. Furthermore, the potting material 13 is provided to seal an interface 37 between the first resin portion 7 and the second resin portion 9, and covers the interface 37.

[0026] Thermistor 5 is provided at a first end portion (lower end portion of lead frame 3 in the height direction), which is one end portion of a pair of lead frames 3 in the longitudinal direction (height direction).

[0027] The longitudinal (height) intermediate portion of each of the pair of lead frames 3 is configured to transmit heat more slowly than the other longitudinal portions (lower and upper portions in the height direction) of the pair of lead frames 3. That is, the value of the amount of heat conducted by the intermediate portion of the lead frame 3 is smaller than the value of the amount of heat conducted by the other longitudinal portions of the lead frame 3. Note that the longitudinal (height) intermediate portion of at least one of the pair of lead frames 3 may transmit heat more slowly than the other longitudinal portions of the pair of lead frames 3.

[0028] More specifically, each of the pair of lead frames 3 is formed in a long and narrow rectangular plate shape. The width direction of the lead frame 3 is the horizontal direction, and the thickness direction of the lead frame 3 is the vertical direction. The pair of lead frames 3 are arranged with a slight distance between them in the width direction.

[0029] The lead frame 3 is entirely made of the same material, but the width dimension of each of the pair of lead frames 3 is reduced over a predetermined length at the intermediate portion 17 in the longitudinal direction (height direction). This suppresses heat transfer in the intermediate portion in the longitudinal direction of the lead frame 3. Instead of reducing the width dimension of the intermediate portion as described above, the shape of the intermediate portion may be changed so that the area of ​​the cross section (cross section taken along a plane perpendicular to the longitudinal direction) of the intermediate portion is reduced. Instead of or in addition to changing the shape of the intermediate portion as described above, the material of the intermediate portion in the longitudinal direction of the lead frame 3 may be changed to one having a lower thermal conductivity than other portions of the lead frame 3. At least one of the pair of lead frames 3 may have a width dimension reduced over a predetermined length at the intermediate portion 17 in the longitudinal direction.

[0030] Here, the temperature sensor 1 will be described in more detail.

[0031] 3 and 5, the lead frame 3A has a first portion 15, a second portion 17, a third portion 19, a fourth portion 21, and a fifth portion 23, and is formed in a generally elongated rectangular plate shape. The lead frame 3A is obtained, for example, by pressing a plate-shaped material.

[0032] The first portion 15 is formed in a rectangular flat plate shape extending in the height direction with a predetermined width and a predetermined thickness. The second portion 17 is also formed in a rectangular flat plate shape extending in the height direction with a predetermined width and a predetermined thickness. The width dimension of the second portion 17 is smaller than the width dimension of the first portion 15, and the height dimension of the second portion 17 is approximately the same as the height dimension of the first portion 15 or smaller than the height dimension of the first portion 15.

[0033] The third region 19 is also formed in a rectangular flat plate shape extending in the height direction with a predetermined width and a predetermined thickness. The width dimension of the third region 19 is larger than the width dimension of the first region 15, and the height dimension of the third region 19 is larger than the height dimension of the first region 15.

[0034] The fourth region 21 is also formed in a rectangular flat plate shape with a predetermined width and thickness, extending in a direction slightly inclined with respect to the height direction. The width dimension of the fourth region 21 is approximately the same as that of the third region 19, and the height dimension of the fourth region 21 (in a direction slightly inclined with respect to the height direction) is smaller than that of the second region 17.

[0035] The fifth region 23 is also formed in a rectangular flat plate shape extending in the height direction with a predetermined width and a predetermined thickness. The width dimension of the fifth region 23 is approximately the same as that of the third region 19, and the height dimension of the fifth region 23 is greater than that of the first region 15 and smaller than that of the third region 19.

[0036] The first region 15, the second region 17, the third region 19, the fourth region 21, and the fifth region 23 are arranged in this order from bottom to top in the height direction.

[0037] The position of the widthwise end (end on the first horizontal end side) of the first region 15, the position of the widthwise end (end on the first horizontal end side) of the second region 17, and the position of the widthwise end (end on the first horizontal end side) of the third region 19 generally coincide with each other in the horizontal direction.

[0038] Since the fourth portion 21 is slightly inclined with respect to the height direction, the position of the widthwise end (the end on the first horizontal end side) of the fifth portion 23 is located closer to the first horizontal end side than the position of the widthwise end (the end on the first horizontal end side) of the third portion 19.

[0039] The other lead frame 3B is formed in the same shape as the lead frame 3A. The lead frame 3B is slightly spaced from the lead frame 3A and is located closer to the second lateral end than the lead frame 3A. The lead frame 3B is disposed symmetrically to the lead frame 3A with respect to a central plane that is perpendicular to the lateral direction and located in the middle between the lead frames 3A and 3B.

[0040] Thermistor 5 is provided at the lower ends of the pair of first portions 15 in the height direction, and on one surface in the thickness direction of lead frame 3 (the surface on the first end side in the vertical direction). Similarly to lead frames 3A and 3B, thermistor 5 is symmetrical with respect to the central plane.

[0041] 3 and 6, the outer shape of the first resin portion 7 is formed into a rectangular parallelepiped that is long in the height direction, and covers all of the first portion 15, all of the second portion 17, and all of the thermistor 5 of the lead frame 3. Furthermore, the upper end portion of the first resin portion 7 in the height direction contacts and covers the lower end portion of the third portion 19 of the lead frame 3 (both sides in the thickness direction of the lower end portion).

[0042] The lateral dimension of the first resin part 7 is roughly the same as the dimension between the end face of the third portion 19 of the lead frame 3A (the end face at the first lateral end) and the end face of the third portion 19 of the lead frame 3B (the end face at the second lateral end).

[0043] 3 and 4, the second resin part 9 is configured to include an insertion part 25, a flange part 27, and a cylindrical part 29. The insertion part 25, the flange part 27, and the cylindrical part 29 are arranged in this order from the bottom to the top.

[0044] The insertion portion 25 is a portion that is inserted into a mating object (not shown) when the temperature sensor 1 is installed in the mating object. The flange portion 27 is a portion that abuts against an end face of the mating object when the temperature sensor 1 is installed in the mating object. The cylindrical portion 29 is a portion into which a connector (not shown) enters when the upper end portion of the lead frame 3 is joined to the connector.

[0045] 3, a recess 31 is formed at the lower end of the insertion portion 25. The insertion portion 25 contacts and covers a portion below the fifth portion 23 of the lead frame 3, the fourth portion 21, and the third portion 19. In addition, by forming the recess 31, an annular gap is formed between the insertion portion 25 and the first resin portion 7.

[0046] An annular recess 33 is provided on the outer periphery of the insertion portion 25 at the middle part in the height direction, and an annular seal member (for example, an O-ring) 35 is installed in this recess.

[0047] An interface 37 between the first resin portion 7 and the second resin portion 9 is formed at the upper end of the recess 31. When the temperature sensor 1 is viewed from the bottom to the top, the interface 37 is formed in a ring shape at the outer periphery of the first resin portion 7. The potting material 13 is provided in the recess 31, and contacts the first resin portion 7 and the second resin portion 9, covering the entire interface 37.

[0048] Here, a description will be given of a manufacturing method (sensor manufacturing method) for the temperature sensor 1. The manufacturing method for the temperature sensor 1 includes a thermistor installation step, a first resin portion installation step, and a second resin portion installation step.

[0049] In the thermistor installation process, the thermistor 5 is installed on the pair of lead frames 3 (see FIG. 5).

[0050] In the first resin portion installation step, after the thermistor 5 is installed on the pair of lead frames 3 in the thermistor installation step, a first resin portion 7 having a predetermined rigidity is provided by transfer molding. More specifically, the thermistor 5 and the portions of the pair of lead frames 3 near the thermistor 5 are covered with epoxy resin by transfer molding to provide the first resin portion 7 (see FIG. 6).

[0051] In the second resin portion providing step, after the first resin portion 7 is provided in the first resin portion providing step, the second resin portion 9 is provided by insert molding. More specifically, the second resin portion 9 is provided by insert molding so as to cover a part of the first resin portion 7 and a part of the pair of lead frames 3, with a portion of the first resin portion 7 near the thermistor 5 being exposed.

[0052] The manufacturing method of the temperature sensor 1 also includes a potting agent providing step, in which an insulating potting agent 13 is provided so as to cover an interface (boundary surface) 37 between the first resin portion 7 and the second resin portion 9 after the second resin portion 9 is provided in the second resin portion providing step.

[0053] The temperature sensor 1 is configured to include a thermistor 5 provided on a pair of lead frames 3, and a first resin portion 7. The first resin portion 7 is made of epoxy resin, and covers the thermistor 5 and the portions of the pair of lead frames 3 near the thermistor 5 with a predetermined rigidity.

[0054] In addition, the temperature sensor 1 is configured to include a second resin part 9 that covers a portion of the first resin part 7 and a portion of the pair of lead frames 3 such that a portion of the first resin part 7 near the thermistor 5 is exposed.

[0055] With this configuration, the strength of the temperature sensor 1 is increased, and the thermistor 5 detects the heat that has flowed only through the first resin part 7, which has high thermal conductivity, improving responsiveness and temperature measurement accuracy.

[0056] That is, the exterior of the thermistor 5 (first resin part 7 provided by transfer molding) is in direct contact with the detection medium (for example LLC). Also, the thermal resistance at the part of the first resin part 7 covering the thermistor 5 is small, so that heat can be efficiently transferred to the thermistor 5 over the shortest distance in a short time. This improves temperature responsiveness and improves temperature measurement accuracy.

[0057] Furthermore, in the temperature sensor 1, the pair of lead frames 3 and thermistor 5 are covered with a single layer of the first resin portion 7, so that the number of parts is reduced and the configuration of the temperature sensor 1 is simplified, improving manufacturability.

[0058] Here, a temperature sensor 301 according to a comparative example will be described with reference to Fig. 7. In the temperature sensor 301, the thermistor 303 and lead wires 305 are coated with epoxy resin 307 that has excellent heat resistance and chemical resistance.

[0059] Since the temperature sensor 301 is coated with epoxy resin 307 with a very thin thickness, the strength of the temperature sensor 301 is low.

[0060] Next, a temperature sensor 311 according to another comparative example will be described with reference to Fig. 8. In the temperature sensor 311, a lead wire portion 315 is connected to a thermistor 313, and both are sealed with a sealing layer 317. In addition, the sealing layer 317 is connected to a resin base 319, and a heat transfer agent 321 is provided in the gap between the sealing layer 317 and the resin base 319.

[0061] Temperature sensor 311 detects heat that has flowed through three layers, namely resin base 319, heat transfer agent 321, and sealing layer 317, using thermistor 313, and therefore has poor response.

[0062] Moreover, in the temperature sensor 1, the heat transfer is suppressed more in the intermediate portion in the longitudinal direction (height direction) of the lead frame 3 than in other portions in the longitudinal direction of the lead frame 3.

[0063] This makes it possible to reduce the amount of heat dissipated from thermistor 5 to the opposite side (upper side) of thermistor 5 through lead frame 3, further improving the response to temperature.

[0064] In the temperature sensor 1, the pair of lead frames 3 have a smaller width dimension at their longitudinal intermediate portion (second portion) 17. This narrows the longitudinal intermediate portion 17 of the lead frame 3, which reduces the amount of heat dissipated from the thermistor 5 to the opposite side (upper side) of the thermistor via the lead frame 3, further improving the temperature responsiveness.

[0065] The lead frame 3 has a large width in the longitudinal direction except for the intermediate portion 17, so that the lead frame 3 is thick. This ensures that the lead frame 3 has a sufficient strength.

[0066] Moreover, in the temperature sensor 1, the lead frame 3 is formed in a long and narrow rectangular plate shape, which makes it easy to form the lead frame 3.

[0067] The manufacturing method of the temperature sensor 1 includes a thermistor installation step, a first resin portion installation step, and a second resin portion installation step. In the first resin portion installation step, the thermistor 5 and a part of the lead frame 3 are covered with epoxy resin by transfer molding to provide the first resin portion 7.

[0068] This makes it possible to obtain a transfer portion (the first resin portion 7 and the portion of the thermistor 5 and lead frame 3 covered by the first resin portion 7) with high dimensional accuracy and high strength, and makes it easier to provide the second resin portion 9 by stable insert molding. As a result, the manufacturability of the temperature sensor 1 is improved.

[0069] In addition, since the temperature sensor 1 is completed through the thermistor installation process, the first resin part installation process, the second resin part installation process, and the potting agent installation process, the number of parts in the temperature sensor 1 is reduced and the structure is simplified.

[0070] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment. [Explanation of symbols]

[0071] 1 Temperature Sensor 3 Lead Frame 5 Thermistor 7 First resin part 9 Second resin part 17 Middle section (second section)

Claims

1. A pair of lead frames; a thermistor provided on the pair of lead frames; a first resin portion made of epoxy resin and covering the thermistor and portions of the pair of lead frames near the thermistor with a predetermined rigidity; a second resin portion that is in contact with and covers a portion of the first resin portion and a portion of the pair of lead frames such that a portion of the first resin portion near the thermistor is exposed; and having The thermal conductivity value of the first resin portion is greater than the thermal conductivity value of the second resin portion. Temperature sensor.

2. Each of the pair of lead frames is elongated, the thermistor is provided at a first end portion, which is one end portion in a longitudinal direction of the pair of lead frames, 2. The temperature sensor according to claim 1, wherein the longitudinal middle portion of at least one of the pair of lead frames is adapted to suppress heat transfer more than other longitudinal portions of the pair of lead frames.

3. Each of the pair of lead frames is formed in a long and narrow rectangular plate shape, The pair of lead frames are arranged slightly apart from each other in the width direction, the thermistor is provided at a first end portion, which is one end portion in a longitudinal direction of the pair of lead frames, 2. The temperature sensor according to claim 1, wherein at least one of said pair of lead frames has a width dimension that is reduced in a longitudinal intermediate portion thereof.

4. a thermistor mounting step of mounting a thermistor on the pair of lead frames; a first resin portion installation step of installing a thermistor on the pair of lead frames in the thermistor installation step, and then covering the thermistor and portions of the pair of lead frames near the thermistor with epoxy resin by transfer molding to provide a first resin portion having a predetermined rigidity; a second resin portion providing step of providing a second resin portion by insert molding after providing a first resin portion in the first resin portion providing step, so as to cover a portion of the first resin portion and portions of the pair of lead frames while exposing a portion of the first resin portion near the thermistor; A method for manufacturing a temperature sensor having the above structure.

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