Infrared sensor

Abstract

Infrared sensor (10), which includes: a printed circuit board (20) having a top main surface (30u) formed with a plurality of electrodes (32a, 32b, 32c, 32d); at least two support sections (72), each of the support sections (72) having an upper surface (72u) and a lower surface (72l) in a vertical direction, each of the support sections (72) further comprising an upper conductor pattern (76a, 76d) formed on the upper surface (72u) and a lower conductor pattern (74a, 74d) formed on the lower surface (72l), the upper conductor pattern (76a, 76d) being electrically connected to the lower conductor pattern (74a, 74d), the lower conductor pattern (74a, 74d) being connected to one of the plurality of electrodes (32a, 32d) of the upper main surface (30u) of the circuit board (20); a FET element (60) located between the at least two support sections (72) and arranged on the upper main surface (30u) of the circuit board (20); a pyroelectric element (90) which is electrically connected to the upper conductor patterns (76a, 76d) of the support sections (72), wherein the pyroelectric element (90) is supported by the support sections (72) such that it is located above the FET element (60); a shielding housing (110) made of metal, wherein the shielding housing (110) is arranged on the upper main surface (30u) and surrounds the pyroelectric element (90), the support sections (72) and the FET element (60); and an infrared transmission filter (130) which is attached to the shielding housing (110), characterized in that the infrared sensor (10) further comprises: a covering resin (120) which is attached to the upper main surface (30u) and covers the shielding housing (110) from the outside, wherein the shielding housing (110) is connected to and attached to the circuit board (20) not only by soldering but also by the covering resin (120).

Description

[0001] The present invention relates to an infrared sensor comprising a pyroelectric element.

[0002] Such an infrared sensor is disclosed, for example, in JP 2012-122908 A (Patent Document 1), JP 2012-37250 A (Patent Document 2), and WO 2006 / 120863A1 (Patent Document 3), the contents of which are incorporated herein by reference. Furthermore, EP 0781982A1 (Patent Document 4) relates to an infrared sensor with a field-effect transistor mounted on a substrate while positioned within a space maintained by a spacer arranged on a base. An infrared detector element is provided on the substrate with the spacer between them, the infrared detector element being in such a planar position that it is superimposed on the field-effect transistor.US 2002 / 0175285A1 (Patent Document 5) relates to an infrared sensor comprising a shaft, a pyroelectric element arranged on one side of the shaft, a conversion circuit for converting the electrical charge generated in the pyroelectric element into a signal, and a plurality of line terminals configured to extend to the other side of the shaft and electrically connected to the conversion circuit.

[0003] The infrared sensor of each patent document 1 to 5 comprises a pyroelectric element and a FET driven by the pyroelectric element.

[0004] It is an object of the present invention to provide an infrared sensor that can be arranged in a space-saving manner.

[0005] One aspect of the present invention provides for an infrared sensor comprising a printed circuit board, at least two support sections, a FET element, and a pyroelectric element. The printed circuit board has a top main surface formed by a plurality of electrodes. Each of the support sections has a top surface and a bottom surface in the vertical direction. Each of the support sections further comprises a top conductor pattern formed on the top surface and a bottom conductor pattern formed on the bottom surface. The top conductor pattern is electrically connected to the bottom conductor pattern. The bottom conductor pattern is connected to one of the plurality of electrodes of the top main surface of the printed circuit board. The FET element is located between the at least two support sections and is arranged on the top main surface of the printed circuit board. The pyroelectric element is electrically connected to the top conductor patterns of the support sections.The pyroelectric element is supported by the support sections so that it is positioned above the FET element. The infrared sensor further comprises a metal shielding housing, the shielding housing being arranged on the upper main surface and surrounding the pyroelectric element, the support sections, and the FET element; a coating resin attached to the upper main surface and covering the shielding housing externally; and an infrared transmission filter attached to the shielding housing. The shielding housing is connected to and attached to the circuit board not only by soldering but also by the coating resin.

[0006] An appreciation of the objectives of the present invention and a more detailed understanding of its structure can be obtained by studying the following description of the preferred embodiment and by referring to the accompanying drawings. Fig. Figure 1 is a perspective view showing an infrared sensor according to an embodiment of the present invention. Fig. 2 is a view that shows the infrared sensor. Fig. 1 along a line II-II in cross-section. Fig. Figure 3 is a perspective exploded view showing the infrared sensor. Fig. Figure 1 shows, but excludes a topcoat resin, a sealing resin, a conductive adhesive, and an adhesive for the infrared sensor. Fig. Figure 4 is a schematic view, mainly showing an arrangement of electrodes in each layer of the multilayer printed circuit board of the infrared sensor. Fig. Figure 1 shows some of the electrodes hatched for better understanding. Fig. Figure 5 is a bottom view showing a FET element of the infrared sensor. Fig. 1 shows. Fig. Figure 6 is a top view showing a spacer for the infrared sensor. Fig. 1 shows. Fig. 7 is a bottom view showing the spacer made of Fig. 6 shows. Fig. Figure 8 is a top view showing a pyroelectric element of the infrared sensor. Fig. 1 shows. Fig. 9 is a bottom view showing the pyroelectric element. Fig. 8 shows. Fig. Figure 10 is a perspective view showing a multitude of the pyroelectric elements arranged on a main circuit board, with the pyroelectric elements undergoing a manufacturing process. Fig. Figure 11 is a diagram showing a noise resistance characteristic of an infrared sensor, which serves as an “example” of the present invention. Fig. Figure 12 is a diagram illustrating an effect caused by a sealing resin of the infrared sensor, which serves as an “example” of the present invention.

[0007] While the invention is accessible in various modifications and alternative forms, specific embodiments are illustrated by way of example in the drawings and are described in detail below. It should be understood, however, that the drawings and the detailed description thereto are not intended to limit the invention to any particular disclosed form, but rather, on the contrary, to cover all modifications, correspondences, and alternatives that fall within the spirit and scope of the present invention as defined in the accompanying claims.

[0008] With reference to the Fig. 1, Fig. 2, Fig. 3 to Fig. Figure 4 shows an infrared sensor 10 surface-mounted according to one embodiment of the present invention. However, the present invention is not limited to the present embodiment. The infrared sensor 10 can, for example, be mounted through a through-hole, similar to the one in patent document 2.

[0009] As in the Fig. 1, Fig. 2, Fig. 3 to Fig. As shown in Figure 4, the infrared sensor 10 according to the present embodiment comprises a printed multilayer printed circuit board (PCB) 20, a FET element 60 arranged on the printed multilayer PCB 20, a spacer block 70 surrounding the FET element 60, a sealing resin 80 sealing the FET element 60 in the spacer block 70, a pyroelectric element 90 supported by the spacer block 70 by a conductive adhesive 100, a shielding housing 110 made of metal and arranged on the printed multilayer PCB 20, a cover resin 120 covering the shielding housing 110, and an infrared transmission filter 130 attached to the cover housing 110.

[0010] As in the Fig. 1, Fig. 2, Fig. 3 to Fig. As shown in Figure 4, the printed multilayer printed circuit board 20 according to the present embodiment is, for example, an epoxy glass printed circuit board made of FR-4, which is popular and inexpensive. The printed multilayer printed circuit board 20 consists of two double-printed boards, namely a first printed circuit board 30 and a second printed circuit board 40. As is best seen in Figure 4, the printed multilayer printed circuit board 20 consists of two double-printed boards, namely a first printed circuit board 30 and a second printed circuit board 40. Fig. As shown in Figure 4, the first circuit board 30 has a first upper main surface 30u and a first lower main surface 30l, while the second circuit board 40 has a second upper main surface 40u and a second lower main surface 40l. As shown in Figure 4, the first circuit board 30 has a first upper main surface 30u and a second lower main surface 30l. Fig. As can be seen in Figure 2, the first upper main surface 30u represents the upper main surface of the multilayer printed circuit board 30, while the second lower main surface 401 represents the lower main surface of the printed multilayer printed circuit board 20.

[0011] As in Fig. As shown in Figure 4, the first upper main surface 30u of the first circuit board 30 is formed with a plurality of electrodes 32a, 32b, 32c, and 32d, while the first lower main surface 301 is formed with a first inner conductive plane 36. The first circuit board 30 is further formed with a plurality of through-holes 34b, 34c, and 34d. According to the present embodiment, each of the through-holes 34b, 34c, and 34d is completely filled with a first filler material made of a conductive or non-conductive resin. In other words, according to the present embodiment, none of the through-holes 34b, 34c, and 34d has a space that is not filled with the first filler material. The first filler materials and the through-holes 34b, 34c, and 34d have first ends on the first upper main surface 30u.The first ends of the first filler materials and the first ends of the through holes 34b, 34c and 34d are coated.

[0012] Electrode 32a has a T-shape. In detail, electrode 32a consists of three end sections and a remaining section, which contains a connected part of the T-shape as a main part. The three end sections are exposed on the first upper main surface 30u, and a solder mask is applied to the remaining section. As will be described later, a solder mask is also applied to another section, which is different from electrode 32a. The solder mask formed on the aforementioned other section is necessarily shown in some figures. However, the solder mask formed on electrode 32a is not shown in any of the figures, so the relationship of the connection of electrode 32a is more clearly shown. Electrodes 32b and 32c are accordingly connected to the through holes 34b and 34c.Electrode 32d has a frame-like section and a T-like section, the frame-like section enclosing electrodes 32a, 32b, and 32c, and the T-like section extending inward from the frame-like section. Electrode 32d is connected to the eight through-holes 34d. As described later, electrode 32d and the through-holes 34d are grounded when the infrared sensor 10 is used.

[0013] The first inner conductive layer 36 is located in a first inner layer of the printed multilayer circuit board 20. The through-holes 34b and 34c, which are connected to the electrodes 32b and 32c, extend to the first inner layer, such that the first inner layer has two (i.e., a plurality of) first predetermined regions. Each of the first predetermined regions consists of one of the cross-sections of the through-holes 34b and 34c and one of the regions 38b and 38c, which enclose the cross-sections of the through-holes 34b and 34c, respectively. The first inner conductive layer 36 completely covers the first inner layer of the printed multilayer circuit board 20, except for the first predetermined regions. Therefore, the first inner conductive layer 36 is separated from the through-holes 34b and 34c by the region 38b and 38c. On the other hand, the eight through holes 34d are connected to the first inner conductive plane 36.

[0014] The second upper main surface 40u of the second circuit board 40 is formed with a second inner conductive plane 44, while the second lower main surface 40l is formed with a plurality of electrodes 48b, 48c, and 48d. The second circuit board 40 is further formed with a plurality of through-holes 42b, 42c, and 42d. Each of the through-holes 42b, 42c, and 42d according to the present embodiment is completely filled with a second filler material made of a conductive or non-conductive resin. In other words, none of the through-holes 42b, 42c, and 42d according to the present embodiment has a space that is not filled with the second filler material. The second filler materials and the through-holes 42b, 42c, and 42d have second ends on the second lower main surface 40l. The second ends of the second filler materials and the second ends of the through holes 42b, 42c and 42d are coated.

[0015] The second inner conductive layer 44 is located in a second inner layer of the printed multilayer circuit board 20. The through-holes 42b and 42c extend to the second inner layer, so that the second inner layer has two (i.e., a plurality of) second predetermined regions. Each of the two predetermined regions consists of one of the cross-sections of the through-holes 42b and 42c and one of the regions 46b and 46c, which enclose the cross-sections of the through-holes 42b and 42c, respectively. The second inner conductive layer 44 completely covers the second inner layer of the printed multilayer circuit board 20, except for the second predetermined regions. Therefore, the second inner conductive layer 44 is separated from the through-holes 42b and 42c by the regions 46b and 46c. On the other hand, the eight through-holes 42d are connected to the second inner conductive layer 44.

[0016] The first inner conductive layer 36 and the second inner conductive layer 44 are placed on top of each other to act as a shielding pattern that almost completely covers the inner layers (i.e. the first inner layer and the second inner layer) of the printed multilayer circuit board 20.

[0017] Electrodes 48b and 48c are connected to the through-holes 42b and 42c accordingly. As can be seen from the aforementioned relationship of the connections, electrodes 48b and 48c function as the input and output terminals of the infrared sensor 10. In detail, electrodes 48b and 48c are each connected to a drain terminal 64b and a source terminal 64c. Electrode 48d is connected to the eight through-holes 42d. Electrode 48d is a grounded electrode. Electrode 48d is separated from electrodes 48b and 48c by solder mask regions 52. Electrode 48d is provided with solder regions 50. Although each of the solder regions 50 is electrically connected to a remaining part of the electrode 48d, each of the solder regions 50 is separated from the remaining part of the electrode 48d by the solder mask region 52, so that it can be seen as an angular region.

[0018] According to the present embodiment, each of the through-holes 34b, 34c, 34d, 42b, 42c, and 42d is buried. Furthermore, each of the through-holes 34b, 34c, and 34d is coated on the upper main surface (the first upper main surface 30u), and each of the through-holes 42b, 42c, and 42d is coated on the lower main surface (the second lower main surface 40l). Accordingly, undesirable environmental influences, such as moisture, transferring from the lower main surface (the second lower main surface 40l) to the upper main surface (the first upper main surface 30u) of the printed multilayer circuit board 20 are prevented.

[0019] As it is in the Fig. 2, Fig. 3 and Fig. As shown in Figure 5, the FET element 60 is surface-mounted. The FET element 60 can be mounted on a surface using an automatic component feeder. In detail, the FET element 60 has a top surface which is formed flat to allow it to be received by a vacuum clamping device of the automatic component feeder. The FET element 60 also has a bottom surface 62 and three (i.e., a plurality of) ports, namely a gate port 64a, a drain port 64b, and a source port 64c, located on the bottom surface 62. The FET element 60 is conveyed to be mounted by the automatic component feeder on the top main surface (the first top main surface 30u).Therefore, the FET element 60 is arranged on the upper main surface (the first upper main surface 30u) of the printed multilayer circuit board 20 in a state in which the bottom surface 62 faces the upper main surface (the first upper main surface 30u) of the printed multilayer circuit board 20. Subsequently, the gate terminal 64a, the drain terminal 64b, and the source terminal 64c are each connected to the electrodes 32a, 32b, and 32c, respectively.

[0020] As in the Fig. 3, Fig. 6 and Fig. As shown in Figure 7, the spacer block 70 according to the present embodiment is made mainly of resin. The spacer block 70 has a closed, frame-like shape with an interior space 70s. The spacer block 70 has two sections opposite each other in the X-direction. As will be described later, the two sections act as support sections 72, which support the pyroelectric element 90. Each of the support sections 72 has a top surface 72u and a bottom surface 721 in the Z-direction (vertical direction). Each of the support sections 72 further has lower conductor patterns 74a and 74d formed on the lower surface 721, and upper conductor patterns 76a and 76d formed on the upper surface 72u. Each of the lower conductor patterns 74a and 74d according to the present embodiment has two electrodes (see Figure 7). Fig. 7). Each of the upper conductor diagrams 76a and 76d has a single electrode that has a square shape (see Fig. 6) The lower circuit pattern 74a is electrically connected to the upper circuit pattern 76a through through holes 78a, while the lower circuit pattern 74d is electrically connected to the upper circuit pattern 76d through through holes 78d. The spacer block 70 is mounted on the upper main surface (the first upper main surface 30u) of the printed multilayer circuit board 20. The lower circuit pattern 74a is connected to opposite ends of the tip of the T-shape of the electrode 32a. The lower circuit pattern 74d is connected to the tip of the T-shaped section of the electrode 32d.

[0021] The FET element 60 is arranged in the interior 70s of the spacer block 70. The sealing resin 80 fills the interior 70s to seal the FET element 60 located therein. According to the present embodiment, the sealing resin 80 completely fills the interior 70s of the spacer block 70. In particular, the connected parts where the gate terminal 64a, the drain terminal 64b, and the source terminal 64c are connected to the corresponding electrodes 32a, 32b, and 32c are completely covered by the sealing resin 80. Accordingly, even if the infrared sensor 10 is used for a long time in a very humid environment, for example, the gate terminal 64a, the drain terminal 64b and the source terminal 64c of the FET element 60 are protected by the sealing resin 80, so that the insulation resistance between the terminals is kept at a predetermined value.According to the present embodiment, sealing with the sealing resin 80 prevents the insulation resistance between the terminals from being reduced, so that the infrared sensor 10 remains stable in terms of performance.

[0022] The sealing resin 80 according to the present embodiment has a linear expansion coefficient of 9.9x10 -6 / °C. Therefore, the linear expansion coefficient of the sealing resin 80 corresponds approximately to the linear expansion coefficient of the printed multilayer circuit board 20, which is an epoxy glass circuit board. According to the present embodiment, a resin having a linear expansion coefficient close to that of the printed multilayer circuit board 20 is used as the sealing resin 80, thus preventing the sealing provided by the sealing resin 80 from being diminished even under very harsh environmental conditions. More precisely, the aforementioned protection of the connections by the sealing resin 80 can be maintained for a long time if a resin having a linear expansion coefficient close to that of the printed multilayer circuit board 20 is used as the sealing resin 80. The aforementioned value of 9.9 x 10 -6 / °C is one of the preferred values ​​for the linear expansion coefficient. In other words, a resin with a linear expansion coefficient of 9.9 x 10 -6 The linear expansion coefficient of the sealing resin 80 is preferably between 5×10⁻⁵ / °C and is exhibited by the sealing resin 80 being used. -6 / °C and 20×10 -6 / °C. Otherwise, the said protection by sealing the connections of the FET element 60a could be destroyed by a stress resulting from a difference between the expansions if the sealing resin 80 expands in an environment of high temperature and high humidity.

[0023] According to the present embodiment, the FET element 60 is arranged within the interior 70s of the spacer block 70, so that the sealing resin 80 effectively seals the FET element 60. According to the present embodiment, the FET element 60 is completely covered by the sealing resin 80, which is attached to the upper main surface (the first upper main surface 30u) of the printed multilayer circuit board 20.

[0024] As it is in the Fig. 8 and Fig. As shown in Figure 9, the pyroelectric element 90 has two sets, each consisting of an upper electrode 92 and a lower electrode 94. As shown in Figure 9, the pyroelectric element 90 has two sets, each consisting of an upper electrode 92 and a lower electrode 94. Fig. As can be seen in Figure 8, the two upper electrodes 92 are coupled together. As can be seen from Figure 8, the two upper electrodes 92 are coupled together. Fig. As can be seen in Figure 9, the two lower electrodes 94 are connected by corresponding connection patterns 96. As can be seen from the Fig. 3, Fig. 8 and Fig. As can be seen in Figure 9, the infrared sensor 10 according to the present embodiment is a so-called dual sensor. As shown in Figure 9, the infrared sensor 10 is a so-called dual sensor. Fig. As shown in Figure 2, the pyroelectric element 90 is connected to and attached to the support sections 72 of the spacer block 70 using a conductive adhesive 100. Specifically, one of the connection patterns 96 is electrically connected to and attached to the upper conductor pattern 76a of one of the support sections 72 by the conductive adhesive 100, while the remaining connection pattern 96 is electrically connected to and attached to the upper conductor pattern 76d of the remaining support section 72 by the conductive adhesive 100. Therefore, the pyroelectric element 90 is supported by the support sections 72 to be located above (i.e., on a positive Z-side of) the FET element 60. Accordingly, the mounting area of ​​the infrared sensor 10 can be reduced. More precisely, according to the present embodiment, the area of ​​the lower main surface 401 of the printed multilayer circuit board 20 of the infrared sensor 10 can be reduced.As described above, the FET element 60 and the pyroelectric element 90 are arranged to be in line with the vertical direction, thus making it possible to reduce the size of the printed multilayer circuit board 20. Accordingly, the infrared sensor 10 can also be of a reduced size.

[0025] As in the Fig. 2 and Fig. As shown in Figure 3, the shielding housing 110 is arranged on the upper main surface (the first upper main surface 30u) of the printed multilayer circuit board 20 to surround and cover the FET element 60, the spacer block 70 (i.e., the support sections 72), and the pyroelectric element 90. Unlike the infrared sensor from Patent Document 3, the shielding housing 110 according to the present embodiment is not formed by bending a stamped metal plate. Therefore, the shielding housing 110 has neither a break nor a gap in its cover portion. Consequently, the infrared sensor 10 according to the present embodiment exhibits improved noise resistance compared to the infrared sensor from Patent Document 3.

[0026] As in Fig. As shown in Figure 2, the shielding housing 110 has a lower housing 112, an upper housing 114 located above (i.e., on the positive Z-side) the lower housing 112, and a boundary section 116 located at a boundary between the lower housing 112 and the upper housing 114. The lower housing 112 is connected to the electrode 32d on the upper main surface (the first upper main surface 30u) of the printed multilayer circuit board 20. The lower housing 112 is smaller than the upper housing 114 in the XY plane. In detail, the lower housing 112 has a lower region in the XY plane, while the upper housing 114 has an upper region in the XY plane, with the lower region being smaller than the upper region. Accordingly, the boundary section 116 is open at the top (in the positive Z-direction). The FET element 60, the spacer block 70 (i.e.The support sections 72 and the pyroelectric element 90 are located within a space enclosed by the lower housing 112 (i.e., within the lower housing 112). According to the present embodiment, each of the FET element 60 and the pyroelectric element 90 is located only a short distance from the shielding housing 110, although the infrared sensor 10 has a large aperture section formed by the upper housing 114. The infrared sensor 10 according to the present embodiment therefore exhibits even better noise resistance.

[0027] As in the Fig. 1 and Fig. As shown in Figure 2, the coating resin 120 is attached to the upper main surface (the first upper main surface 30u) of the printed multilayer circuit board 20, covering the shielding housing 110 from the outside. Accordingly, the shielding housing 110 is connected to and attached to the printed multilayer circuit board 20 not only by soldering but also by the coating resin 120. The coating resin 120 is made of a resin, such as an epoxy resin, which is not damaged even in a soldering furnace. When the infrared sensor 10 is mounted to a circuit board (not shown) according to the present embodiment, the infrared sensor 10 is placed in the soldering furnace. Even if the solder metal connecting the shielding housing 110 to the printed multilayer circuit board 20 is melted again in the furnace, the coating resin 120 can hold the shielding housing 110 and the printed multilayer circuit board 20 firmly connected.Accordingly, the space in which the pyroelectric element 90 and the FET element 60 are housed can remain airtight. Furthermore, the shielding housing 110, which is made of metal susceptible to temperature changes in the external environment, is covered with the resin 120, so that the temperature changes of the external environment do not significantly affect it.

[0028] As in Fig. As shown in Figure 2, the boundary section 116 is located below the infrared transmission filter 130. The boundary section 116 supports the infrared transmission filter 130. In detail, the infrared transmission filter 130 is attached to the boundary section 116 from above (i.e., along the negative Z-direction). The infrared transmission filter 130 is connected to and fastened to the shielding housing 110 using the conductive adhesive 100. Any gap remaining between the infrared transmission filter 130 and the shielding housing 110 after this fastening with the conductive adhesive 100 is filled with an adhesive 140. This makes the space in which the pyroelectric element 90 is housed even more airtight.

[0029] The infrared sensor 10, which has the aforementioned structure, is manufactured as described below. As in Fig. As shown in Figure 10, a plurality of infrared sensors 10 are simultaneously formed on a first printed circuit board 20'. Subsequently, the first printed circuit board 20' is cut into multiple infrared sensor 10 parts. A solder paste is printed onto the first printed circuit board 20', which can be divided into a plurality of printed multilayer printed circuit boards 20. An automatic component feeder then arranges the FET elements 60, the spacer blocks 70, and the shielding housings 110 on the first printed circuit board 20' (i.e., on the printed multilayer printed circuit boards 20) in that order. The solder paste is then melted in the melting furnace, so that the FET elements 60, the spacer blocks 70, and the shielding housings 110 are bonded to the first printed circuit board 20' (i.e., to the printed multilayer printed circuit boards 20).The sealing resin 80 is then poured into each of the interior spaces 70s to fill the space between the FET element 60 and the spacer block 70. The topcoat resin 120 is then poured over to cover the shielding housing 110. The conductive adhesive 100 is then applied to each of the spacer blocks 70. The pyroelectric elements 90 are then attached to the corresponding spacer blocks 70. The infrared transmission filters 130 are then mounted to the corresponding shielding housings 110. Specifically, the infrared transmission filter 130 and the shielding housing 110 are bonded together using the conductive adhesive 100 and the adhesive 140. Finally, the first circuit board 20' is cut into the numerous parts of the infrared sensor 10.

[0030] As can be seen from the above description, the infrared sensor 10, according to the present embodiment, is assembled by layering the components onto the printed multilayer circuit board 20 in a sequential order. Accordingly, the plurality of infrared sensors 10 are formed simultaneously and efficiently on the first circuit board 20'.

[0031] The present invention is not limited to the aforementioned embodiment. The present invention can be modified and adapted in various ways.

[0032] For example, according to the embodiment described above, the spacer block 70 has a closed, frame-like shape. However, the spacer block 70 can also have an open shape. For example, the spacer block 70 can have a C-shape. Furthermore, the spacer block 70 described above has two support sections 72 and coupling sections that couple the support sections 72 to each other. However, the spacer block 70 can also consist of only the two support sections 72. In this case, the two support sections 72 are arranged to be spaced apart from each other, while the FET element 60 is provided between the support sections 72. Furthermore, the infrared sensor 10 can have three or more support sections 72. In each case, the FET element 60 is located between the at least two support sections 72.In any case, it is preferred that the FET element 60, in particular the connecting parts of the terminals 64a, 64b and 64c of the FET element 60, which are connected to the electrodes 32a, 32b and 32c of the printed multilayer circuit board 20, are completely covered with the sealing resin 80 in order not to be exposed to a very humid atmosphere.

[0033] The infrared sensor 10, which has the structure according to the embodiment described above, served as an “example.” Additionally, an infrared sensor having a structure as disclosed in patent document 3, and an infrared sensor having a structure as disclosed in patent document 2, were provided as “Comparative Example 1” and “Comparative Example 2,” respectively. Furthermore, an infrared sensor having a structure similar to the “example” was provided as “Comparative Example 3.” The FET element 60 of “Comparative Example 3” was sealed with a resin having a linear expansion coefficient of over 20 x 10 -6 / °C, instead of the sealing resin 80, which has a linear expansion coefficient of 9.9x10 -6 / °C. A noise resistance property of each of the “Example”, “Comparative Example 1”, and “Comparative Example 2”, was measured under conditions in which low-frequency noise was applied. A voltage across the source terminal 64c of each of the “Example” and “Comparative Example 3” was measured after each of the “Example” and “Comparative Example 3” was subjected to an environmental influence of high temperature (specifically 60°C) and high humidity (specifically 95%) for a period of time. The results of the measurements are presented accordingly in the Fig. 11 and Fig. 12 shown.

[0034] The shielding housing 110 of the infrared sensor 10 of the "Example" is not formed by bending a metal plate, so that the covering part of the shielding housing 110 of the "Example", unlike the infrared sensor of Comparative Example 1 (Patent Document 3), is formed without any interruption or gap. Accordingly, the infrared sensor 10 of the "Example", as shown from Fig. As is evident from Figure 11, the infrared sensor exhibits a better noise resistance property than the infrared sensor of "Comparative Example 1", which is surface-mounted similarly to the infrared sensor 10 of the "Example". Furthermore, the infrared sensor 10 of the "Example" exhibits a noise resistance property that corresponds to the infrared sensor of "Comparative Example 2", which is mounted in a through-hole and is of a CAN type.

[0035] As from Fig.As can be seen in Figure 12, the "Example" shows an almost unchanged and stable voltage at the source terminal 64c when the time period is equal to or less than 1,000 hours. On the other hand, the voltage at the source terminal 64c of "Comparative Example 3" increases gradually when the time period is equal to or more than 250 hours. This can be explained by the fact that the sealing resin of "Comparative Example 3" expands under the influence of high humidity, thus reducing the protection of the terminal.

Claims

[1] Infrared sensor (10) comprising: a printed circuit board (20) having a top main surface (30u) formed with a plurality of electrodes (32a, 32b, 32c, 32d); at least two support sections (72), each of the support sections (72) having an upper surface (72u) and a lower surface (72l) in a vertical direction, each of the support sections (72) further comprising an upper conductor pattern (76a, 76d) formed on the upper surface (72u) and a lower conductor pattern (74a, 74d) formed on the lower surface (72l), the upper conductor pattern (76a, 76d) being electrically connected to the lower conductor pattern (74a, 74d), the lower conductor pattern (74a, 74d) being connected to one of the plurality of electrodes (32a, 32d) of the upper main surface (30u) of the circuit board (20); a FET element (60) located between the at least two support sections (72) and arranged on the upper main surface (30u) of the circuit board (20); a pyroelectric element (90) which is electrically connected to the upper conductor patterns (76a, 76d) of the support sections (72), wherein the pyroelectric element (90) is supported by the support sections (72) such that it is located above the FET element (60); a shielding housing (110) made of metal, wherein the shielding housing (110) is arranged on the upper main surface (30u) and surrounds the pyroelectric element (90), the support sections (72) and the FET element (60); and an infrared transmission filter (130) which is attached to the shielding housing (110), characterized by , that the infrared sensor (10) further comprises: a covering resin (120) which is attached to the upper main surface (30u) and covers the shielding housing (110) from the outside, wherein the shielding housing (110) is connected to and attached to the circuit board (20) not only by soldering but also by the covering resin (120). [2] Infrared sensor (10) according to claim 1, wherein the FET element (60) is completely covered with a sealing resin (80) which is attached to the upper main surface (30u) of the circuit board (20). [3] Infrared sensor (10) according to claim 2, wherein: the printed circuit board (20) is an epoxy glass printed circuit board; and the sealing resin (80) has a linear expansion coefficient between 5×10 -6 / °C and 20×10 -6 / °C. [4] Infrared sensor (10) according to one of claims 2 or 3, wherein the infrared sensor (10) further comprises a spacer block (70), wherein: the spacer block (70) has a closed frame-like shape which has an interior space (70s) therein; the support sections (72) are each part of the spacer block (70); the FET element (60) is arranged in the interior (70s) of the spacer block (70); and The sealing resin (80) fills the interior (70s) of the spacer block (70) to seal the FET element (60). [5] Infrared sensor (10) according to any one of claims 1 to 4, wherein: the circuit board (20) is formed with a plurality of through holes (34b, 34c, 34d); Each of the through-holes (34b, 34c, 34d) is filled with a filler material made of a conductive or non-conductive resin; and the filler materials and the through holes (34b, 34c, 34d) have ends on the upper main surface (30u) of the printed circuit board (20), wherein the ends of the filler materials and the ends of the through holes (34b, 34c, 34d) are coated. [6] Infrared sensor (10) according to claim 5, wherein: the printed circuit board (20) is a multilayer printed circuit board (20) which has an inner conductive layer (36) located in an inner layer of the multilayer printed circuit board (20); through holes (34b, 34c) extend to the inner layer such that the inner layer has a plurality of predetermined regions, each of the predetermined regions consisting of a cross-section of one of the through holes (34b, 34c) and enclosing a region of the cross-section of the through hole (34b, 34c); and the inner conductive plane (36) the inner layer of the multilayer printed circuit board (20), except for one or more of the predetermined areas, completely covered. [7] Infrared sensor (10) according to any one of claims 1 to 6, wherein: the shielding housing (110) comprises a lower housing (112), an upper housing (114) and a boundary section (116) located at a boundary between the upper housing (114) and the lower housing (112); the upper housing (114) has an upper region in a horizontal plane perpendicular to the vertical direction, wherein the lower housing (112) has a lower region in a horizontal plane, the lower region being smaller than the upper region; the pyroelectric element (90), the support sections (72) and the FET element (60) are located inside the lower housing (112); and the boundary section (116) is located below the infrared transmission filter (130), wherein the boundary section (116) supports the infrared transmission filter (130). [8] Infrared sensor (10) according to any one of claims 1 to 7, wherein: the FET element (60) is surface-mounted, wherein the FET element (60) has a bottom surface (62) and a plurality of terminals (64a, 64b, 64c) located on the bottom surface (62), and the FET element (60) is arranged on the upper main surface (30u) of the circuit board (20), wherein the bottom surface (62) faces the upper main surface (30u), and wherein the plurality of terminals (64a, 64b, 64c) are connected to the plurality of electrodes (32a, 32b, 32c).

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