Infrared detector

Abstract

An infrared detector is provided with: a package having a base part, first to third pins, and a lid part; and a plurality of thermopile chips disposed on the main surface of the base part. The first and second thermopile chips are electrically connected in series, and a first chip unit including the first and second thermopile chips and a second chip unit including the third thermopile chip are electrically connected in parallel. The first and second pins are arranged in a second direction via a first straight line, the first and third pins are arranged in a first direction via a second straight line, and the first thermopile chip is arranged on the second straight line and on a straight line connecting the first and third pins. The second and third thermopile chips are arranged so as to be aligned on the first straight line via a reference position.

Description

Technical Field

[0001] The invention relates to an infrared detector. Background Art

[0002] As a technology related to an infrared detector, for example, Patent Document 1 describes an infrared detection element including a package having a base portion and a plurality of thermopile chips arranged on a main surface of the base portion. In the infrared detection element described in Patent Document 1, the plurality of thermopile chips are electrically connected in series.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2000-19019 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In recent years, for example, as the application of infrared detectors in various fields and uses continues to develop, a high-sensitivity infrared detector is desired. In the above-mentioned technology, due to the presence of multiple thermopile chips, there is a risk that the resistance value of the circuit constituting the infrared detector becomes large, making it difficult to improve the sensitivity. In addition, in the above-mentioned technology, there are restrictions on the arrangement of the thermopile chips on the main surface, making it difficult to ensure a large light receiving area, and thus it is difficult to improve the sensitivity.

[0008] Therefore, an object of the present disclosure is to provide an infrared detector capable of improving sensitivity.

[0009] Means used to solve problems

[0010] (1) An infrared detector according to one aspect of the present disclosure comprises: a package having a base portion, first to third leads protruding from a main surface of the base portion, and a cover portion arranged on the main surface of the base portion and defining a storage space together with the base portion; and a plurality of thermopile chips arranged on the main surface of the base portion, the plurality of thermopile chips having first to third thermopile chips, the first and second thermopile chips being electrically connected in series, a first chip unit including the first and second thermopile chips being electrically connected in parallel with a second chip unit including the third thermopile chip, and when viewed from a direction perpendicular to the main surface of the base portion, a straight line passing through a reference position and extending in a first direction is defined as a first straight line, and a straight line passing through the reference position and extending in a second direction orthogonal to the first direction is defined as a second straight line, the first and second leads are arranged so as to be arranged in the second direction via the first straight line, the first and third leads are arranged so as to be arranged in the first direction via the second straight line, the first thermopile chip is arranged on the second straight line and on a straight line connecting the first and third leads, and the second and third thermopile chips are arranged so as to be arranged on the first straight line via the reference position.

[0011] In an infrared detector according to one aspect of the present disclosure, a first chip unit including first and second thermopile chips electrically connected in series is electrically connected in parallel with a second chip unit including a third thermopile chip, which can reduce the resistance value of the circuit compared to the case where the first to third thermopile chips are electrically connected in series. In addition, since it is a packaging structure in which a plurality of pins protrude from the main surface, when there are restrictions on the configuration of the thermopile chips on the main surface, the configuration of the first to third thermopile chips can be optimized to ensure a larger light-receiving area. Therefore, according to the infrared detector according to one aspect of the present disclosure, the sensitivity can be improved.

[0012] (2) In the infrared detector described in (1) above, a light passage opening may be formed in the cover portion and is opposite to the main surface of the base portion, and the light passage opening overlaps with the first to third thermopile chips and does not overlap with the first to third pins when viewed from a direction perpendicular to the main surface of the base portion. In this way, it is possible to prevent infrared rays passing through the light passage opening from being diffusely reflected at the first to third pins to generate noise, and to allow infrared rays to be efficiently incident on the light-receiving surfaces of the first to third thermopile chips.

[0013] (3) In the infrared detector described in (1) or (2) above, the plurality of thermopile chips may further include a fourth thermopile chip, which is disposed on the main surface of the base and included in the second chip unit, and the third and fourth thermopile chips are electrically connected in series, and the first and fourth thermopile chips are arranged in a manner of being arranged on the second straight line via the reference position when viewed from a direction perpendicular to the main surface of the base. In this way, the resistance value of the circuit can be suppressed to the same resistance value as when one thermopile chip is used, and the arrangement of the first to fourth thermopile chips can be optimized to ensure a larger light receiving area.

[0014] (4) In the infrared detector described in any one of (1) to (3) above, a light passage opening may be formed in the cover portion and is opposite to the main surface of the base portion, and the light passage opening overlaps with the first to fourth thermopile chips and does not overlap with the first to third pins when viewed from a direction perpendicular to the main surface of the base portion. Thus, it is possible to prevent infrared rays passing through the light passage opening from being diffusely reflected at the first to third pins to generate noise, and to allow infrared rays to be efficiently incident on the light-receiving surfaces of the first to fourth thermopile chips.

[0015] (5) In the infrared detector described in any one of (1) to (4) above, the first thermopile chip may be electrically connected to the third pin via the first wire, the second thermopile chip may be electrically connected to the second pin via the second wire, the third thermopile chip may be electrically connected to the third pin via the third wire, the fourth thermopile chip may be electrically connected to the second pin via the fourth wire, the first and second thermopile chips may be electrically connected to each other via the fifth wire, and the third and fourth thermopile chips may be electrically connected to each other via the sixth wire. In this case, as the arrangement of the first to fourth thermopile chips can be optimized, the length of each wire can be shortened to reduce the resistance value, and the sensitivity can be further improved.

[0016] (6) In the infrared detector described in any one of (1) to (5) above, the thermopile chip and the light passage opening may be rectangular when viewed from a direction perpendicular to the main surface of the base, and a straight line along the diagonal of the thermopile chip may be inclined by 45° relative to a straight line along the diagonal of the light passage opening. Thus, infrared rays can be prevented from being irradiated to the first to third pins via the light passage opening, and infrared rays can be efficiently incident on the light receiving surfaces of the plurality of thermopile chips.

[0017] (7) In the infrared detector described in any one of (1) to (6) above, the thermopile chip and the light passage opening are both square in shape when viewed from a direction perpendicular to the main surface of the base, and the length of one side of the light passage opening is greater than twice the length of one side of the thermopile chip. By enlarging the light passage opening in this way, infrared rays can be efficiently incident on the light receiving surface of the thermopile chip.

[0018] (8) In the infrared detector described in any one of (1) to (7) above, each of the thermopile chips may include a film formed in a central portion and an edge portion surrounding the film when viewed from a direction perpendicular to the main surface of the base portion, and the light passage opening may overlap with the film of the thermopile chip and not overlap with at least a portion of the edge portion when viewed from a direction perpendicular to the main surface of the base portion. Thus, infrared rays can be efficiently incident on the film having the warm junction formed thereon, and a structure in which the light passage opening does not overlap with the first to third pins when viewed from a direction perpendicular to the main surface of the base portion can be easily realized.

[0019] (9) In the infrared detector described in any one of (1) to (8) above, the light passage opening may be arranged on a straight line connecting the first and second pins and on a straight line connecting the first and third pins when viewed from a direction perpendicular to the main surface of the base. Thus, the light passage opening is arranged on the plurality of thermopile chips, and infrared rays can be efficiently incident on the light receiving surfaces of the plurality of thermopile chips through the light passage opening.

[0020] (10) In the infrared detector described in any one of (1) to (9) above, when viewed from a direction perpendicular to the main surface of the base, at least a portion of the second thermopile chip is located between the first thermopile chip and the fourth thermopile chip, and at least a portion of the third thermopile chip is located between the first thermopile chip and the fourth thermopile chip. Thus, the second thermopile chip and the third thermopile chip can be brought close to each other in the first direction, and infrared rays can be efficiently incident on the light-receiving surfaces of the second and third thermopile chips.

[0021] (11) In the infrared detector described in any one of (1) to (10) above, the package may further include a fourth pin protruding from the main surface of the base, and when viewed from a direction perpendicular to the main surface of the base, the second and fourth pins are arranged in a manner arranged along the first direction via a second straight line, and the fourth thermopile chip is arranged on a straight line connecting the second and fourth pins. In this way, infrared rays can be efficiently incident on the light-receiving surface of the fourth thermopile chip.

[0022] (12) In the infrared detector described in any one of (1) to (11) above, a light passage opening may be formed in the cover portion and is opposite to the main surface of the base portion, and the light passage opening overlaps with the first to fourth thermopile chips and does not overlap with the first to fourth pins when viewed from a direction perpendicular to the main surface of the base portion. Thus, infrared rays can be prevented from being irradiated to the first to fourth pins via the light passage opening, and infrared rays can be efficiently incident on the light-receiving surfaces of the first to fourth thermopile chips.

[0023] (13) In the infrared detector described in any one of (1) to (12) above, the plurality of thermopile chips may further include a fifth thermopile chip disposed on the main surface of the base portion and included in the first chip unit, and the first, second, and fifth thermopile chips may be electrically connected in series. Thus, the presence of the fifth thermopile chip may further improve the sensitivity.

[0024] (14) In the infrared detector described in any one of (1) to (13) above, the plurality of thermopile chips may further include a fifth thermopile chip, which is disposed on the main surface of the base and included in the first chip unit, the first, second and fifth thermopile chips are electrically connected in series, and the fifth thermopile chip is disposed between the second and third thermopile chips in a manner overlapping with the reference position when viewed from a direction perpendicular to the main surface of the base. Thus, due to the presence of the fifth thermopile chip, the sensitivity can be further improved, and the arrangement of the first to fifth thermopile chips can be optimized to ensure a larger light receiving area.

[0025] (15) In the infrared detector described in any one of (1) to (14) above, a light passage opening may be formed in the cover portion and is opposite to the main surface of the base portion, and the light passage opening overlaps with the first to fifth thermopile chips and does not overlap with the first to third pins when viewed from a direction perpendicular to the main surface of the base portion. Thus, infrared rays can be prevented from being irradiated to the first to third pins via the light passage opening, and infrared rays can be efficiently incident on the light-receiving surfaces of the first to fifth thermopile chips.

[0026] (16) In the infrared detector described in any one of (1) to (15), the reference position overlaps with the center position of the light passage opening when viewed from a direction perpendicular to the main surface of the base. Thus, when viewed from a direction perpendicular to the main surface of the base, the plurality of thermopile chips can be arranged with the center position of the light passage opening as a reference, and infrared rays passing through the light passage opening can be efficiently incident on the light receiving surfaces of the plurality of thermopile chips.

[0027] Effects of the Invention

[0028] According to the present disclosure, it is possible to provide an infrared detector that can improve sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a plan view showing the infrared detector according to the first embodiment.

[0030] Figure 2 It is along Figure 1 Cross-sectional view along line II-II.

[0031] Figure 3 It is along Figure 1Cross-sectional view along line III-III.

[0032] Figure 4 To express Figure 1 A cross-sectional perspective view of a thermopile chip.

[0033] Figure 5 It is schematically indicated Figure 4 Figure 2. A cross-section of a thermopile chip.

[0034] Figure 6 It means omitted Figure 1 A plan view of the window portion of the infrared detector.

[0035] Figure 7 Yes means Figure 1 A perspective view of a portion of an infrared detector.

[0036] Figure 8 Yes means Figure 1 A plan view showing a schematic structure of an infrared detector.

[0037] Fig. 9 Yes means Figure 1 A schematic circuit diagram of the electrical connections of the thermopile chip in the infrared detector.

[0038] Fig.10 It is a perspective view showing a part of the infrared detector according to the second embodiment.

[0039] Fig.11 Yes means Fig.10 A plan view showing a schematic structure of an infrared detector.

[0040] Fig.12 Yes means Fig.10 A schematic circuit diagram of the electrical connections of the thermopile chip in the infrared detector.

[0041] Fig.13 It is a perspective view showing a part of the infrared detector according to the third embodiment.

[0042] Fig.14 Yes means Fig.13 A plan view showing a schematic structure of an infrared detector.

[0043] Fig.15 Yes means Fig.13 A schematic circuit diagram of the electrical connections of the thermopile chip in the infrared detector.

[0044] Fig.16 It is a perspective view showing a part of the infrared detector involved in the first modification.

[0045] Fig.17 Yes means Fig.16 A plan view showing a schematic structure of an infrared detector.

[0046] Fig.18 It is a perspective view showing a part of the infrared detector involved in the second modification.

[0047] Fig.19 Yes means Fig.18 A plan view showing a schematic structure of an infrared detector. DETAILED DESCRIPTION

[0048] Hereinafter, the implementation mode will be described in detail with reference to the accompanying drawings. In each of the drawings, the same or equivalent parts are given the same reference numerals, and repeated descriptions are omitted. For the convenience of description, three directions orthogonal to each other are respectively set as "X direction", "Y direction" and "Z direction" for description.

[0049] (First Embodiment)

[0050] like Figure 1 , Figure 2 as well as Figure 3 As shown, the infrared detector 1 involved in the first embodiment is a detector for detecting infrared rays. The infrared detector 1 is used for applications such as radiation thermometers, gas analysis, and flame detection. The infrared detector 1 here is a high-sensitivity detector for flame detection, and detects infrared rays radiated by resonance of CO2 from flames. The infrared detector 1 includes a package 10 having a storage space R, and a plurality of thermopile chips 30 arranged in the storage space R.

[0051] The package 10 has a base 11, a first pin 12, a second pin 13, a third pin 14, a fourth pin 15, a cover 16 and a window 17. The base 11 is in the shape of a disk with the Z direction being the thickness direction. A plurality of thermopile chips 30 are mounted on a main surface 11a on one side of the base 11 in the Z direction. The main surface 11a is a circular plane when viewed from the Z direction. A flange 11b protruding radially outward is provided at the end on the other side of the base 11 in the Z direction. The base 11 is formed of a material containing Kovar, for example. The diameter of the base 11 is, for example, about 10 mm. The thickness of the base 11 is, for example, about 2 mm.

[0052] The first to fourth pins 12 to 15 are terminal components protruding from the main surface 11a of the base 11. The first to fourth pins 12 to 15 extend in the Z direction in a manner penetrating the base 11. The first to fourth pins 12 to 15 also protrude from the main surface 11c on the other side of the Z direction of the base 11. The first to fourth pins 12 to 15 are arranged separately from each other. An insulating portion 11d such as sealing glass is provided around the first to third pins 12 to 14 in the base 11. Thus, the first to third pins 12 to 14 are insulated from the base 11. No insulating portion 11d is provided around the fourth pin 15 in the base 11. Thus, the fourth pin 15 is electrically connected to the base 11 and functions as a ground wire (see Fig. 9 The height from the main surface 11a of the base portion 11 to the upper surface of the first to fourth pins 12 to 15 (the protrusion amount of the first to fourth pins 12 to 15) is greater than the height from the main surface 11a of the base portion 11 to the upper surface of the thermopile chip 30 (the thickness of the thermopile chip 30).

[0053] The cover 16 is arranged on the main surface 11a of the base 11, and divides (delimits) the storage space R together with the base 11. The cover 16 is in the shape of a circular cup that is open on the other side in the Z direction. The inner diameter of the cover 16 corresponds to the outer diameter of the base 11. A flange portion 16a protruding radially outward is provided at the end of the opening side of the cover 16. The cover 16 is coaxially arranged with the base 11 in a manner covering the main surface 11a of the base 11. The cover 16 is fixed to the base 11 in a state where its flange portion 16a abuts against the flange portion 11b of the base 11. When viewed from the Z direction, the center position of the cover 16 coincides with the center position of the main surface 11a of the base 11. The storage space R is divided by the bottom surface and inner peripheral surface of such a cover 16 and the main surface 11a of the base 11.

[0054] The cover 16 is provided with a light passage opening 18 facing the main surface 11a of the base 11. The light passage opening 18 is a through hole that penetrates the cover 16 in the Z direction and connects the inside and outside of the cover 16 (accommodation space R). When viewed from the Z direction, the light passage opening 18 is rectangular, specifically, square.

[0055] The distance from the upper surface of the thermopile chip 30 to the inner surface of the thermopile chip 30 opposite to the cover 16 is, for example, about 1 mm. The distance from the upper surface of the thermopile chip 30 to the inner surface of the thermopile chip 30 opposite to the cover 16 is less than the thickness of the base. By reducing the distance from the upper surface of the thermopile chip 30 to the inner surface of the thermopile chip 30 opposite to the cover 16, the field of view of the thermopile chip 30 can be increased, and infrared rays can be efficiently incident on the light receiving surface. The distance from the main surface 11c on the other side of the base 11 in the Z direction to the outer surface of the cover 16 (the outer surface of the part where the window 17 is installed) is, for example, about 3 mm.

[0056] The window portion 17 is provided on the cover portion 16 in such a manner as to block the light passage opening 18. Here, the window portion 17 is fixed on the inner side of the cover portion 16 at the edge of the light passage opening 18 of the cover portion 16 in such a manner as to block the light passage opening 18. The window portion 17 is in the shape of a plate with the Z direction being the thickness direction. The window portion 17 is embedded in the light passage opening 18 from the inner side of the cover portion 16. The window portion 17 is formed of a material (e.g., silicon) that is permeable to infrared rays. The window portion 17, for example, constitutes a bandpass filter that cuts off light of wavelengths other than the wavelength of infrared rays. Infrared rays are incident on the accommodation space R through the window portion 17. In order to embed the cover portion 16, the window portion 17 is formed with a portion with a reduced thickness at the outer edge. Thus, the fixing strength between the cover portion 16 and the window portion 17 can be improved. The thickness of the window portion 17 is, for example, about 0.5 mm. The thickness of the window portion 17 is greater than the thickness of the thermopile chip 30.

[0057] The thermopile chip 30 is a thermal detection sensor that uses the Seebeck effect to obtain a thermoelectromotive force proportional to the incident energy of infrared rays. The thermopile chip 30 can detect the absolute amount of infrared rays. A plurality of thermopile chips 30 are arranged on the main surface 11a of the base 11. When viewed from the Z direction, the thermopile chip 30 is a rectangular chip. When viewed from the Z direction, the thermopile chip 30 is square. The surface of the thermopile chip 30 constitutes a light-receiving surface. The thermopile chip 30 is a single-element thermopile. When viewed from the Z direction, the central portion of the light-receiving surface of the thermopile chip 30 has a higher sensitivity than the edge portion.

[0058] like Figure 4 and Figure 5As shown, the thermopile chip 30 includes a substrate 3, an insulating film 4, an infrared absorption film 5, and a plurality of thermocouples 6 electrically connected in series. The substrate 3 is made of silicon, for example. The substrate 3 is rectangular when viewed from the Z direction, and a rectangular opening 3h is formed in the center. The insulating film 4 is provided on the substrate 3 in a manner that blocks the opening 3h formed in the substrate 3. The portion of the insulating film 4 that blocks the opening 3h of the substrate 3 constitutes a film 7. The film 7 is rectangular in shape and is suspended in the hollow. As a result, a space K is formed between the film 7 and the main surface 11a of the base 11, so that thermal separation of the film 7 and the base 11 can be achieved. The insulating film 4 is made of SiO2 or SiN, for example. A plurality of thermocouples 6 are formed inside the insulating film 4 in a manner that the warm junction 6a is located at the film 7 and the cold junction 6b is located at the edge 9 surrounding the film 7.

[0059] The infrared absorbing film 5 is provided on the film 7 on the surface of the insulating film 4. The infrared absorbing film 5 is a film for improving the absorption efficiency of infrared rays. The infrared absorbing film 5 is made of, for example, TiN. An electrode pad (output terminal) 8 is formed on the edge portion 9 of the film 7 on the surface surrounding the insulating film 4. The electrode pad 8 is a terminal for taking out the thermoelectromotive force as a signal to the outside, and is electrically connected to a plurality of thermocouples 6. The electrode pad 8 is formed at each of the four corners of the surface of the insulating film 4. Two of the four electrode pads 8 are electrically connected to the outside via a wire. When infrared rays are incident on the film 7, the warm junction 6a located at the film 7 becomes hot, and a temperature difference is generated between the warm junction 6a located at the edge portion 9 surrounding the film 7. By taking out the thermoelectromotive force accompanying the temperature difference from the electrode pad 8 as a signal to the outside, infrared rays can be detected. The size of the thermopile chip 30 is, for example, about 1 to 2 mm on one side. The thickness of the thermopile chip 30 is, for example, about 200 μm. The thickness of the substrate 3 is, for example, 200 μm, and the thickness of the insulating film 4 is, for example, several μm (in Figure 5 In the figure, the thickness of the insulating film 4 is shown as thick for the sake of explanation. The thickness of the insulating film 4 is smaller than the thickness of the substrate 3. The size of the film 7 is, for example, about 1 to 1.5 mm on one side.

[0060] like Figure 6 As shown, when viewed from the Z direction, the straight line along the diagonal of the thermopile chip 30 is inclined by 45° relative to the straight line along the diagonal of the light passage opening 18. When viewed from the Z direction, the length of one side of the light passage opening 18 is greater than twice the length of one side of the thermopile chip 30. The plurality of thermopile chips 30 include a first thermopile chip 31, a second thermopile chip 32, a third thermopile chip 33, and a fourth thermopile chip 34. The first and second thermopile chips 31, 32 are included in the first chip unit U1. The third and fourth thermopile chips 33, 34 are included in the second chip unit U2.

[0061] like Figure 8As shown, when viewed from the Z direction, the infrared detector 1 of this embodiment has the following characteristics when a straight line passing through the reference position O and extending in the X direction (first direction) is set as the first straight line L1, and a straight line passing through the reference position O and extending in the Y direction (second direction) is set as the second straight line L2. The reference position O is the center position (center of gravity position) of the main surface 11a of the base portion 11.

[0062] The first and second leads 12 and 13 are arranged on the main surface 11a in a manner that they are arranged along the Y direction via the first straight line L1. The first and third leads 12 and 14 are arranged on the main surface 11a in a manner that they are arranged along the X direction via the second straight line L2. The second and fourth leads 13 and 15 are arranged on the main surface 11a in a manner that they are arranged along the X direction via the second straight line L2.

[0063] In other words, when viewed from the Z direction, the first to fourth pins 12 to 15 are located at the corners of a square formed on the main surface 11a with the X direction and the Y direction as sides. The first to fourth pins 12 to 15 are located in each of the regions divided into four by the first and second straight lines L1 and L2 on the main surface 11a. The distance from each of the first to fourth pins 12 to 15 to the first straight line L1 is equal to the distance from each of the first to fourth pins 12 to 15 to the second straight line L2. When viewed from the Z direction, the first to fourth pins 12 to 15 are respectively arranged at rotationally symmetrical positions of 90° with the reference position O as the center. The distance from each of the first to fourth pins 12 to 15 to the first straight line L1 and the distance from each of the first to fourth pins 12 to 15 to the second straight line L2 are, for example, about 1 mm to 2 mm. The distance from the first pin 12 to the fourth pin 15 and the distance from the second pin 13 to the third pin 14 are, for example, about 5 mm.

[0064] When viewed from the Z direction, the first and fourth thermopile chips 31 and 34 are arranged on the second straight line L2 via the reference position O. The second and third thermopile chips 32 and 33 are arranged on the first straight line L1 via the reference position O. The first thermopile chip 31 is arranged on the straight line connecting the first and third pins 12 and 14. The fourth thermopile chip 34 is arranged on the straight line connecting the second and fourth pins 13 and 15.

[0065] When viewed from the Z direction, a portion of the second thermopile chip 32 is located between the first thermopile chip 31 and the fourth thermopile chip 34. A portion of the third thermopile chip 33 is located between the first thermopile chip 31 and the fourth thermopile chip 34. The second thermopile chip 32 and the third thermopile chip 33 are close to each other in the X direction. The first thermopile chip 31 is close to the second and third thermopile chips 32, 33 in the Y direction. The second and third thermopile chips 32, 33 are close to the fourth thermopile chip 34 in the Y direction. The thermopile chips 30 are arranged in a staggered manner on the main surface 11a. The thermopile chips 30 are arranged in the Y direction in a manner that forms a long rhombus as a whole. A maximum of two thermopile chips 30 are arranged in the X direction and a maximum of three are arranged in the Y direction.

[0066] When viewed from the Z direction, the light passage opening 18 overlaps with the first to fourth thermopile chips 31 to 34, and does not overlap with the first to fourth pins 12 to 15. When viewed from the Z direction, the light passage opening 18 includes at least a portion of the first to fourth thermopile chips 31 to 34, and does not include the first to fourth pins 12 to 15. In other words, there is a light passage opening 18 directly above the first to fourth thermopile chips 31 to 34, but there is no light passage opening 18 directly above the first to fourth pins 12 to 15. When viewed from the Z direction, the reference position O overlaps (coincides) with the center position of the light passage opening 18.

[0067] When viewed from the Z direction, the light passage opening 18 overlaps with at least a portion of the film 7 formed in the center of the first to fourth thermopile chips 31 to 34. When viewed from the Z direction, the light passage opening 18 does not overlap with at least a portion of the edge portion 9 of the thermopile chip 30 surrounding the film 7. When viewed from the Z direction, the light passage opening 18 overlaps with a portion of the insulating portion 11d of the first to third leads 12 to 14. When viewed from the Z direction, the light passage opening 18 overlaps with the entire surface of the second and third thermopile chips 32 and 33, and overlaps with a portion of the first and fourth thermopile chips 31 and 34. One corner of the light passage opening 18 is located on the second straight line L2 on the opposite side of the reference position O across the first thermopile chip 31, and the corner opposite to the corner is located on the second straight line L2 on the opposite side of the reference position O across the fourth thermopile chip 34. The size of the light passage opening 18 is, for example, about 4 to 5 mm on one side.

[0068] When viewed from the Z direction, the light passage opening 18 is arranged on a straight line connecting any two of the first to fourth pins 12 to 15. Specifically, when viewed from the Z direction, the light passage opening 18 is arranged on a straight line connecting the first and second pins 12 and 13, and on a straight line connecting the first and third pins 12 and 14. When viewed from the Z direction, the light passage opening 18 is arranged on a straight line connecting the second and fourth pins 13 and 15, and on a straight line connecting the third and fourth pins 14 and 15. When viewed from the Z direction, the light passage opening 18 is arranged on a straight line connecting the first and fourth pins 12 and 15, and on a straight line connecting the second and third pins 13 and 14.

[0069] like Figure 8 and Fig. 9 As shown, the first and second thermopile chips 31, 32 are electrically connected in series. The third and fourth thermopile chips 33, 34 are electrically connected in series. The first chip unit U1 including the first and second thermopile chips 31, 32 and the second chip unit U2 including the third and fourth thermopile chips 33, 34 are electrically connected in parallel.

[0070] The first thermopile chip 31 is electrically connected to the third pin 14 through the first wire 41. The second thermopile chip 32 is electrically connected to the second pin 13 through the second wire 42. The third thermopile chip 33 is electrically connected to the third pin 14 through the third wire 43. The fourth thermopile chip 34 is electrically connected to the second pin 13 through the fourth wire 44. The first and second thermopile chips 31 and 32 are electrically connected to each other through the fifth wire 45. The third and fourth thermopile chips 33 and 34 are electrically connected to each other through the sixth wire 46. Figure 8 In the figure, the electrode pads 8 formed on the surface of the thermopile chip 30 are omitted (see Figure 7 ), but each of the wires 41 to 46 and the electrode pads 8 (refer to Figure 7 )Electrical connection (in the following Figure 8 , Fig.11 , Fig.14 , Fig.17 , Fig.19 (same in ).

[0071] The wire bonding between the thermopile chip 30 and the second and third pins 13 and 14 may also use the second reinforcement method, for example. The second reinforcement method is a method of forming a reinforcement ball at the second bonding location where the strength tends to be weaker than the first bonding location after performing normal wire bonding. In addition, the wire bonding between multiple thermopile chips 30 may also use the BSOB (Bond Stick on Ball) method. The BSOB method is a method of forming a ball in advance at the location where the second bonding is performed before performing normal wire bonding to strengthen the second bonding location.

[0072] As described above, in the infrared detector 1, by electrically connecting the first chip unit U1 including the first and second thermopile chips 31 and 32 electrically connected in series and the second chip unit U2 including the third thermopile chip 33 in parallel, the resistance value (total resistance value) of the circuit can be reduced compared to the case where the first to third thermopile chips 31 to 33 are electrically connected in series. In addition, since the first to fourth pins 12 to 15 are a package structure protruding from the main surface 11a, the configuration of the first to third thermopile chips 31 to 33 can be optimized under the constraints of the configuration of the thermopile chips 30 on the main surface 11a, thereby ensuring a larger light receiving area. A plurality of thermopile chips 30 can be effectively spread over a large area on the main surface 11a. Therefore, according to the infrared detector 1, the sensitivity can be improved.

[0073] In the infrared detector 1, the cover portion 16 is provided with a light passage opening 18, and when viewed from the Z direction, the light passage opening 18 overlaps with the first to third thermopile chips 31 to 33, and does not overlap with the first to third pins 12 to 14. Thus, it is possible to prevent infrared rays passing through the light passage opening 18 from being irradiated to the first to third pins 12 to 14, and the infrared rays from being diffusely reflected at the first to third pins 12 to 14 to generate noise, and to allow the infrared rays to be efficiently incident on the light receiving surfaces of the first to third thermopile chips 31 to 33.

[0074] In the infrared detector 1, the plurality of thermopile chips 30 further includes a fourth thermopile chip 34. The third and fourth thermopile chips 33 and 34 are electrically connected in series. When viewed from the Z direction, the first and fourth thermopile chips 31 and 34 are arranged on the second straight line L2 in a manner arranged via the reference position O. Thus, the resistance value of the circuit can be suppressed to the same resistance value as when one thermopile chip 30 is used, and the arrangement of the first to fourth thermopile chips 31 to 34 can be optimized to ensure a larger light receiving area.

[0075] In the infrared detector 1, when viewed from the Z direction, the light passage opening 18 overlaps with the first to fourth thermopile chips 31 to 34, and does not overlap with the first to third pins 12 to 14. Thus, it is possible to prevent the infrared rays passing through the light passage opening 18 from being diffusely reflected by the first to third pins 12 to 14 to generate noise, and the infrared rays can be efficiently incident on the light receiving surfaces of the first to fourth thermopile chips 31 to 34.

[0076] In the infrared detector 1, the first and third thermopile chips 31 and 33 are electrically connected to the third pin 14, the second and fourth thermopile chips 32 and 34 are electrically connected to the second pin 13, the first and second thermopile chips 31 and 32 are electrically connected to each other, and the third and fourth thermopile chips 33 and 34 are electrically connected to each other according to the first to sixth wires 41 to 46. In this case, as the arrangement of the first to fourth thermopile chips 31 to 34 can be optimized, the length of the first to sixth wires 41 to 46 can be shortened to reduce the resistance value, and the sensitivity can be further improved.

[0077] In the infrared detector 1, when viewed from the Z direction, the thermopile chip 30 and the light passage opening 18 are both rectangular. The straight line along the diagonal of the thermopile chip 30 is inclined at 45 degrees relative to the straight line along the diagonal of the light passage opening 18. As a result, it is possible to prevent infrared rays from being irradiated to the first to third pins 12 to 14 via the light passage opening 18, and it is possible to make infrared rays efficiently incident on the light receiving surfaces of the plurality of thermopile chips 30. In addition, since the light passage opening 18 is inclined at 45 degrees as described above, it is possible to easily realize the above-mentioned configuration structure in which the light passage opening 18 overlaps with the first to third thermopile chips 31 to 33 and does not overlap with the first to third pins 12 to 14.

[0078] In the infrared detector 1, the thermopile chip 30 and the light passage opening 18 are both square in shape when viewed from the Z direction. The length of one side of the light passage opening 18 is greater than twice the length of one side of the thermopile chip 30. By enlarging the light passage opening 18 in this way, infrared rays can be efficiently incident on the light receiving surface of the thermopile chip 30.

[0079] In the infrared detector 1, when viewed from the Z direction, each of the thermopile chips 30 includes a film 7 formed in the center and an edge portion 9 surrounding the film 7. When viewed from the Z direction, the light-passing opening 18 overlaps with the film 7 of the thermopile chip 30 and does not overlap with at least a portion of the edge portion 9. Thus, infrared rays can be efficiently incident on the film 7 having a warm junction, and a structure in which the light-passing opening 18 does not overlap with the first to third pins 12 to 14 when viewed from the Z direction can be easily realized. Figure 6 In the case where it is assumed that the light passage opening 18 overlaps with all parts of the plurality of thermopile chips 30 , the light passage opening 18 also overlaps with the first to third leads 12 to 14 .

[0080] In the infrared detector 1, when viewed from the Z direction, the light passage opening 18 is arranged on a straight line connecting the first and second pins 12 and 13, and is arranged on a straight line connecting the first and third pins 12 and 14. Thus, the light passage opening 18 is arranged on the light receiving surfaces of the plurality of thermopile chips 30, so that infrared rays can be effectively incident on the light receiving surfaces of the plurality of thermopile chips 30 through the light passage opening 18.

[0081] In the infrared detector 1, when viewed from the Z direction, at least a portion of the second thermopile chip 32 is located between the first thermopile chip 31 and the fourth thermopile chip 34. When viewed from the Z direction, at least a portion of the third thermopile chip 33 is located between the first thermopile chip 31 and the fourth thermopile chip 34. Thus, the second thermopile chip 32 and the third thermopile chip 33 can be brought close to each other in the X direction, and infrared rays can be efficiently incident on the light receiving surfaces of the second and third thermopile chips 32 and 33.

[0082] In the infrared detector 1, the package 10 further includes a fourth pin 15, and when viewed from the Z direction, the second and fourth pins 13 and 15 are arranged in the X direction via the second straight line L2, and the fourth thermopile chip 34 is arranged on the straight line connecting the second and fourth pins 13 and 15. Thus, infrared rays can be efficiently incident on the light receiving surface of the fourth thermopile chip 34.

[0083] In the infrared detector 1, when viewed from the Z direction, the light passage opening 18 overlaps with the first to fourth thermopile chips 31 to 34, and does not overlap with the first to fourth pins 12 to 15. Thus, infrared rays can be prevented from being irradiated to the first to fourth pins 12 to 15 via the light passage opening 18, and infrared rays can be efficiently incident on the light receiving surfaces of the first to fourth thermopile chips 31 to 34.

[0084] In the infrared detector 1, when viewed from the Z direction, the reference position O overlaps with the center position of the light passage opening 18. Thus, when viewed from the Z direction, the plurality of thermopile chips 30 can be arranged with the center position of the light passage opening 18 as a reference, and infrared rays passing through the light passage opening 18 can be efficiently incident on the light receiving surfaces of the plurality of thermopile chips 30.

[0085] In addition, in the infrared detector 1, since a plurality of thermopile chips 30 are arranged as described above, it is possible to configure the plurality of thermopile chips 30 in a manner such that the central portion of the light receiving surface of each of the plurality of thermopile chips 30 is close to the central position of the light passage opening 18, for example, compared with the case where the plurality of thermopile chips 30 are arranged in a lattice shape. The center distance of the light receiving surface of each thermopile chip 30 can be reduced. As a result, the central portion of the thermopile chip 30 has a higher sensitivity than the edge portion 9, so that the infrared rays passing through the light passage opening 18 can be effectively incident on the light receiving surfaces of the plurality of thermopile chips 30. In addition, the field angle of the infrared rays incident on the plurality of thermopile chips 30 via the light passage opening 18 can be increased. As a result, the sensitivity of the infrared detector 1 can be further improved.

[0086] In the infrared detector 1, when viewed from the Z direction, the light passage opening 18 is arranged on a straight line connecting the second and fourth pins 13 and 15, and is arranged on a straight line connecting the third and fourth pins 14 and 15. In addition, when viewed from the Z direction, the light passage opening 18 is arranged on a straight line connecting the first and fourth pins 12 and 15, and is arranged on a straight line connecting the second and third pins 13 and 14. According to such a structure, since the light passage opening 18 is arranged on the light receiving surfaces of the plurality of thermopile chips 30, infrared rays can be efficiently incident on the light receiving surfaces of the plurality of thermopile chips 30 through the light passage opening 18.

[0087] In the infrared detector 1, a general package in which the positions of the first to fourth pins 12 to 15 are standardized relative to the main surface 11a of the base 11 is used as the package 10. This allows commonality of components with general packages. As a general package, for example, TO-5 can be used.

[0088] (Second Embodiment)

[0089] Next, a second embodiment will be described. In the description of this embodiment, points different from the above-mentioned first embodiment will be described, and duplicate descriptions will be omitted.

[0090] like Fig.10 , Fig.11 and Fig.12 As shown, the infrared detector 101 involved in the second embodiment is different from the first embodiment described above in that it does not include the fourth thermopile chip 34. The first chip unit U1 including the first and second thermopile chips 31 and 32 is electrically connected in parallel with the second chip unit U2 including the third thermopile chip 33. The second thermopile chip 32 is electrically connected to the second pin 13 through the seventh wire 47. The third thermopile chip 33 is electrically connected to the second pin 13 through the eighth wire 48.

[0091] As described above, the infrared detector 101 also has the same effects as those of the first embodiment, that is, the effects of being able to improve sensitivity and the like.

[0092] (Third Embodiment)

[0093] Next, a third embodiment will be described. In the description of this embodiment, points different from the first embodiment described above will be described, and duplicate descriptions will be omitted.

[0094] like Fig.13 , Fig.14 and Fig.15As shown, the infrared detector 201 involved in the third embodiment is different from the above-mentioned first embodiment in that it further includes a fifth thermopile chip 35. When viewed from the Z direction, the fifth thermopile chip 35 is arranged in a manner overlapping with the reference position O. When viewed from the Z direction, the fifth thermopile chip 35 is arranged between the second and third thermopile chips 32 and 33. When viewed from the Z direction, the fifth thermopile chip 35 is arranged between the first and fourth thermopile chips 31 and 34. The fifth thermopile chip 35 is electrically connected in series with the first and second thermopile chips 31 and 32. The fifth thermopile chip 35 is included in the first chip unit U1.

[0095] The second thermopile chip 32 is arranged on a straight line connecting the first and second pins 12 and 13. The third thermopile chip 33 is arranged on a straight line connecting the third and fourth pins 14 and 15. The thermopile chips 30 are arranged in a cross shape in the X direction and the Y direction as a whole. A maximum of three thermopile chips 30 are arranged in the X direction and a maximum of three are arranged in the Y direction. When viewed from the Z direction, the light passes through the opening 18 and overlaps with the first to fifth thermopile chips 31 to 35. The first chip unit U1 including the first, second and fifth thermopile chips 31, 32, 35 is electrically connected in parallel to the second chip unit U2 including the third and fourth thermopile chips 33, 34.

[0096] The first thermopile chip 31 is electrically connected to the third pin 14 through the ninth wire 51. The second thermopile chip 32 is electrically connected to the second pin 13 through the tenth wire 52. The third thermopile chip 33 is electrically connected to the third pin 14 through the eleventh wire 53. The fourth thermopile chip 34 is electrically connected to the second pin 13 through the twelfth wire 54. The first and fifth thermopile chips 31 and 35 are electrically connected to each other through the thirteenth wire 55. The second and fifth thermopile chips 32 and 35 are electrically connected to each other through the fourteenth wire 56. The third and fourth thermopile chips 33 and 34 are electrically connected to each other through the fifteenth wire 57.

[0097] As described above, the infrared detector 201 also has the same effect as the first embodiment, that is, the effect of improving sensitivity. The infrared detector 201 further includes the fifth thermopile chip 35. Thus, due to the presence of the fifth thermopile chip 35, the sensitivity can be further improved. In the infrared detector 201, when viewed from the Z direction, the fifth thermopile chip 35 is arranged to overlap the reference position O between the second and third thermopile chips 32 and 33. Thus, the arrangement of the first to fifth thermopile chips 31 to 35 can be optimized to ensure a larger light receiving area.

[0098] In the infrared detector 201, the light passage opening 18 overlaps with the first to fifth thermopile chips 31 to 35, and does not overlap with the first to fourth pins 12 to 15. Thus, infrared rays can be prevented from being irradiated to the first to fourth pins 12 to 15 via the light passage opening 18, and infrared rays can be efficiently incident on the light receiving surfaces of the first to fifth thermopile chips 31 to 35.

[0099] (Variation Example)

[0100] One aspect of the present disclosure is not limited to the above-described embodiment.

[0101] In the above embodiment, the direction of the thermopile chip 30 when viewed from the Z direction (the angle between each side of the thermopile chip 30 and the X direction and the Y direction) is not particularly limited. Fig.16 and Fig.17 As shown, in the infrared detector 1A according to the modified example, the first to fourth thermopile chips 31 to 34 may be arranged in a manner corresponding to the infrared detector 1 (see Figure 7 ) is arranged in a manner that the direction of the thermopile chip 30 is rotated 45° when viewed from the Z direction. In this case, the first to fourth thermopile chips 31 to 34 are arranged in a manner that the angle between each side and the X direction or the Y direction is 45°. The first to fourth thermopile chips 31 to 34 are arranged in a lattice shape. The first to fourth thermopile chips 31 to 34 are arranged in a square shape as a whole. In this case, the same effect as the above-mentioned embodiment is also achieved.

[0102] In addition, for example Fig.18 and Fig.19 As shown, in the infrared detector 101A according to the modified example, the first to third thermopile chips 31 to 33 may be arranged relative to the infrared detector 101 (see Fig.10 ) is arranged in a direction rotated 45° from the Z direction. In this case, the first to third thermopile chips 31 to 33 are arranged in a manner that the angle between each side and the X direction or the Y direction is 45°. In this case, the same effect as the above embodiment is achieved.

[0103] In the above embodiment, the first to fifth thermopile chips 31 to 35 are rectangular chips of the same size, but the present invention is not limited thereto. Part or all of the first to fifth thermopile chips 31 to 35 may be different shapes from each other, or may be different sizes from each other. In the above embodiment, the first pin 12 is not used, but the present invention is not limited thereto. For example, the first pin 12 may be electrically connected to an output correction thermistor disposed on the main surface 11a.

[0104] In the above embodiment, the light passage opening 18 is formed so as not to overlap with the first to fourth pins 12 to 15 when viewed from the Z direction, but it is sufficient to form the light passage opening 18 so as not to overlap with the first to third pins 12 to 14. In this case, it is possible to prevent infrared rays from irradiating the first to third pins 12 to 14. In the above embodiment, the reference position O is set to the center position of the main surface 11a of the base 11 and the center position of the light passage opening 18, but it is not limited thereto. The reference position O may be any position on the main surface 11a.

[0105] Each structure in one embodiment or variant example described above can be arbitrarily applied to each structure in other embodiments or variant examples. In the above, "45°" includes not only a perfect 45°, but also approximately 45°, and may include errors in manufacturing and design. In the above, "2 times" includes not only a perfect 2 times, but also approximately 2 times, and may include errors in manufacturing and design. In the above, "arranged in a manner arranged along the first / second direction" is not limited to the case where multiple elements are arranged on a straight line extending parallel to the first or second direction, but may also be a case where multiple elements are offset in a direction intersecting the first / second direction.

[0106] Description of Reference Numerals

[0107] 1, 1A, 101, 101A, 201: infrared detector, 7: film, 9: edge portion, 10: package, 11: base portion, 11a: main surface, 12: first pin, 13: second pin, 14: third pin, 15: fourth pin, 16: cover portion, 18: light passage opening, 30: thermopile chip, 31: first thermopile chip, 32: second thermopile chip, 33: third thermopile chip, 34: fourth thermopile chip, 35: fifth thermopile chip, 41: first wire, 42: second wire, 43: third wire, 44: fourth wire, 45: fifth wire, 46: sixth wire, L1: first straight line, L2: second straight line, O: reference position, R: accommodation space, U1: first chip unit, U2: second chip unit.

Claims

1. An infrared detector, wherein: have: A package having a base portion, first to third leads protruding from a main surface of the base portion, and a cover portion disposed on the main surface of the base portion and defining a storage space together with the base portion; as well as a plurality of thermopile chips arranged on the main surface of the base portion, The plurality of thermopile chips include first to third thermopile chips, The first and second thermopile chips are electrically connected in series, A first chip unit including the first and second thermopile chips is electrically connected in parallel with a second chip unit including the third thermopile chip, When viewed from a direction perpendicular to the main surface of the base portion, a straight line passing through a reference position and extending in a first direction is set as a first straight line, and a straight line passing through the reference position and extending in a second direction orthogonal to the first direction is set as a second straight line, The first and second pins are arranged in a manner of being arranged along the second direction via the first straight line, The first and third pins are arranged in the first direction via the second straight line. The first thermopile chip is arranged on the second straight line and on a straight line connecting the first and third pins. The second and third thermopile chips are arranged to be aligned on the first straight line through the reference position.

2. The infrared detector according to claim 1, wherein: The cover portion has a light passage opening opposite to the main surface of the base portion. The light passage opening overlaps the first to third thermopile chips and does not overlap the first to third leads when viewed from a direction perpendicular to the main surface of the base portion.

3. The infrared detector according to claim 1, wherein: The plurality of thermopile chips further include a fourth thermopile chip, the fourth thermopile chip being arranged on the main surface of the base portion and included in the second chip unit, The third and fourth thermopile chips are electrically connected in series, The first and fourth thermopile chips are arranged to be aligned on the second straight line through the reference position when viewed from a direction perpendicular to the main surface of the base portion.

4. The infrared detector according to claim 3, wherein: The cover portion has a light passage opening opposite to the main surface of the base portion. The light passage opening overlaps the first to fourth thermopile chips and does not overlap the first to third leads when viewed from a direction perpendicular to the main surface of the base portion.

5. The infrared detector according to claim 3 or 4, wherein: The first thermopile chip is electrically connected to the third pin via a first wire. The second thermopile chip is electrically connected to the second pin via a second wire, The third thermopile chip is electrically connected to the third pin via a third wire. The fourth thermopile chip is electrically connected to the second pin via a fourth wire, The first and second thermopile chips are electrically connected to each other via a fifth wire, The third and fourth thermopile chips are electrically connected to each other through a sixth wire.

6. The infrared detector according to claim 2 or 4, wherein: The thermopile chip and the light passage opening are both rectangular when viewed from a direction perpendicular to the main surface of the base portion, and a straight line along a diagonal of the thermopile chip is inclined by 45° relative to a straight line along a diagonal of the light passage opening.

7. The infrared detector according to claim 2 or 4, wherein: When viewed from a direction perpendicular to the main surface of the base portion, the thermopile chip and the light passage opening are both square-shaped, and a length of one side of the light passage opening is greater than twice a length of one side of the thermopile chip.

8. The infrared detector according to claim 2 or 4, wherein: Each of the thermopile chips includes a film formed in a central portion and an edge portion surrounding the film when viewed in a direction perpendicular to the main surface of the base portion. The light passage opening overlaps with the film of the thermopile chip and does not overlap with at least a part of the edge portion when viewed from a direction perpendicular to the main surface of the base portion.

9. The infrared detector according to claim 2 or 4, wherein: The light passage opening is arranged on a straight line connecting the first and second leads and on a straight line connecting the first and third leads when viewed from a direction perpendicular to the main surface of the base portion.

10. The infrared detector according to claim 3 or 4, wherein: When viewed from a direction perpendicular to the main surface of the base portion, at least a portion of the second thermopile chip is located between the first thermopile chip and the fourth thermopile chip, and at least a portion of the third thermopile chip is located between the first thermopile chip and the fourth thermopile chip.

11. The infrared detector according to claim 3, wherein: The package further includes a fourth lead protruding from the main surface of the base portion, When viewed from a direction perpendicular to the main surface of the base portion, The second and fourth pins are arranged in the first direction via the second straight line. The fourth thermopile chip is disposed on a straight line connecting the second and fourth pins.

12. The infrared detector according to claim 11, wherein: The cover portion has a light passage opening opposite to the main surface of the base portion. The light passage opening overlaps the first to fourth thermopile chips and does not overlap the first to fourth leads when viewed from a direction perpendicular to the main surface of the base portion.

13. The infrared detector according to claim 1 or 3, wherein: The plurality of thermopile chips further include a fifth thermopile chip that is disposed on the main surface of the base portion and included in the first chip unit. The first, second and fifth thermopile chips are electrically connected in series.

14. The infrared detector according to claim 3, wherein: The plurality of thermopile chips further include a fifth thermopile chip that is disposed on the main surface of the base portion and included in the first chip unit. The first, second and fifth thermopile chips are electrically connected in series, The fifth thermopile chip is arranged between the second and third thermopile chips so as to overlap with the reference position when viewed from a direction perpendicular to the main surface of the base portion.

15. The infrared detector according to claim 14, wherein: The cover portion has a light passage opening opposite to the main surface of the base portion. The light passage opening overlaps the first to fifth thermopile chips and does not overlap the first to third leads when viewed from a direction perpendicular to the main surface of the base portion.

16. The infrared detector according to claim 2 or 4, wherein: The reference position overlaps with a center position of the light passage opening when viewed from a direction perpendicular to the main surface of the base portion.

Images