JP2009128227A - Infrared detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared detector capable of miniaturizing, thinning, and preventing degradation of detection sensitivity. <P>SOLUTION: The infrared detector A comprises a circuit block 3 to which mounting surface 33a a heat detection element 1 is mounted and an electronic component 20 of an electronic circuit element 2 is embedded and a metal package consisting of a stem 4 and a cap 5 to house them; a terminal pin 6 for outputting a detected signal is provided to penetrate between the surface of the stem 4 opposite to the side of the circuit block and the mounting surface 33a of the heat detection element 1 in the circuit block 3 and electrically connected with the circuit block 3 at the mounting surface 33a; a filter 9 formed of a conductive material and transmissive for infrared radiation is attached to the cap 5 in a manner to block a lighting window aperture 5a and capable of communicating with the cap 5; and a shielding conductor pattern 33f is formed around the terminal pin 6 in the mounting surface 33a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an infrared detector used for human body detection and the like.

  Conventionally, various infrared detectors used for human body detection and the like have been provided. In such infrared detectors, heat detection elements (infrared detection elements and heat ray detection elements) that detect the amount of infrared radiation emitted from the human body are provided. Pyroelectric elements using the pyroelectric effect are often used.

  As this type of infrared detector, the infrared rays generated by the action of the human body are condensed on the light receiving part of the pyroelectric element by the lens, and the signal due to the polarization of the pyroelectric element generated according to the change of the infrared ray is converted into a current-voltage conversion circuit. After the signal is converted into a voltage signal, a predetermined frequency band is selectively amplified by a band-pass amplifier, and a detection signal of “H” level or “L” level is output from a window comparator in which a threshold is set in advance. Proposed. The detection signal of such an infrared detector is used for intrusion detection for crime prevention and load control such as lighting.

  In Patent Document 1, as shown in FIGS. 14A to 14C, a three-dimensional circuit block (MID substrate) 100 made of a resin molded product has a heat detection element 110 made of a pyroelectric element and a bandpass. An infrared detector A is disclosed that is miniaturized by mounting an electronic circuit element 120 constituting an amplifier or window comparator, and enclosing and sealing it in a package made up of a cap 130 and a stem 140. In FIGS. 14B and 14C, reference numeral 150 denotes a terminal pin used for connection to an external circuit (that is, a terminal pin for power supply, a terminal pin for ground, a terminal pin for detection signal output), Reference numeral 131 denotes an infrared passage window provided in the cap 130 for allowing infrared rays to enter the heat detection element 110. The infrared passage window 131 is provided with a band-pass optical filter 160 that allows only infrared rays in a predetermined frequency range to pass. Is done.

  The three-dimensional circuit block 100 is a vertically long block that has a vertical surface and a vertical surface, and has an electronic circuit element 120 mounted on the vertical surface and a heat detection element 110 on the top. A recess 101 that creates a space for heat insulation is integrally formed, and the heat detection element 110 is mounted on the three-dimensional circuit block 100 across the recess 101. The concave portion 101 prevents the portion of the heat detection element 110 that receives infrared rays from coming into contact with the three-dimensional circuit block 100. Therefore, when the heat detection element 110 receives infrared rays, the infrared energy does not escape and the sensitivity is increased. be able to.

Moreover, in what is shown in patent document 1, as shown in FIG.14 (b), (c), in the package (CAN package) which consists of metal caps 130 and stems 140, the heat detection element 110 and the three-dimensional circuit By housing the block 100, the heat detection element 110 and the three-dimensional circuit block 100 are shielded from external noise. This is because the charge of the heat detection element 110 is very small, and therefore it is necessary to perform a very large amplification using an amplifier or the like. This is because noise is also amplified, making it difficult to distinguish the original signal from noise.
Japanese Patent No. 3211074 (see paragraphs [0018] to [0021] and FIGS. 6 to 13 in particular)

  In the infrared detector A shown in Patent Document 1 described above, since the concave portion 101 for floating the heat detection element 110 is directly formed in the three-dimensional circuit block 100, the number of parts can be reduced and the cost can be reduced. In addition, since the infrared detector A shown in Patent Document 1 can shorten the distance between the heat detection element 110 and the input part of the band-pass amplifier, it is difficult for external noise to enter and has a configuration that is resistant to noise. Further, since the heat detection element 110 and the three-dimensional circuit block 100 are housed in a package including the metal cap 130 and the stem 140, there is an advantage that a configuration extremely resistant to external noise can be realized. In addition, since the bandpass amplifier and the window comparator can be integrated into an IC, further miniaturization can be achieved.

  However, in the infrared detector A shown in Patent Document 1, an electronic component or an IC is mounted on a circuit portion in which the three-dimensional circuit block 100 stands vertically and forms a front surface and a back surface. , The package becomes vertically long.

Therefore, in the infrared detector A shown in Patent Document 1, since the thickness of the device to which the infrared detector A is attached is limited, it is difficult to reduce the thickness, and there is a request for reducing the size and thickness of such a device. Here, when the three-dimensional circuit block 100 was downsized to reduce the size of the infrared detector A as a whole, there were the following two problems.

  The first problem is that the circuit space for mounting the electronic circuit elements is insufficient. That is, in the above-described three-dimensional circuit block 100, the portion where the front and back surfaces are formed is used as a circuit space for mounting electronic circuit elements, but when the three-dimensional circuit block 100 is simply reduced in size, naturally The circuit space is narrowed, and a sufficient space cannot be secured. Therefore, the three-dimensional circuit block 100 cannot be simply reduced in size.

  The second problem is that the distance between the heat detection element 110 and the detection signal output unit (terminal pin for detection signal output) or the input unit for power supply (terminal pin for power supply) is short. It is. That is, since the change in the electric charge of the heat detection element 110 is very weak, the subsequent circuit (the bandpass amplifier in the above example) amplifies the femtoampere level current change to the level of several hundred millivolts and outputs it. In addition, external power supply voltage (superimposed noise from commercial power supply and radiation noise from mobile phone) is also superimposed on the supplied power supply voltage, so detection signal output terminal pins and power supply terminal pins When the distance to the heat detection element approaches, capacitive coupling occurs between them, which causes a problem such as an oscillation phenomenon or a deterioration in frequency characteristics, resulting in a problem that the detection sensitivity is deteriorated. Therefore, it is necessary to sufficiently separate the heat detection element 110 from the detection signal output unit or the power supply input unit, which hinders downsizing.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an infrared detector that can be reduced in size and thickness, and can prevent deterioration in detection sensitivity.

  In order to achieve the above object, in the invention of claim 1, a circuit block having a heat detection element and an electronic circuit element constituting a drive circuit for the heat detection element, and a stem and a stem to which the circuit block is attached And a metal package made of a cap attached to the stem so as to accommodate the circuit block between the first resin layer in which at least a part of the electronic circuit element is embedded, A second resin layer provided on a side opposite to the stem side of the first resin layer via a shield layer, and heat detection comprising one surface of the second resin layer opposite to the shield layer side A recess for heat insulation is formed on the mounting surface for the element, and the heat detection element is mounted on the mounting surface so as to straddle the recess for heat insulation, and is located at a portion of the cap facing the heat detection element. For daylighting A hole is formed, and the cap is an infrared detector that is made of a conductive material and transmits infrared rays, closes the window hole, and is connected to the cap so as to be electrically connected to the cap. The terminal pin for electrically connecting the drive circuit of the circuit block and the external circuit is provided so as to penetrate between the surface opposite to the first resin layer side of the stem and the mounting surface. The surface is electrically connected to the circuit block, and a shielding conductor pattern is formed around the terminal pin on the mounting surface.

  According to the first aspect of the invention, since the electronic circuit element is embedded in the first resin layer, a space (mounting area) for mounting the electronic circuit element that has been an obstacle to downsizing in the standing direction. Therefore, the size and thickness can be significantly reduced as compared with the conventional example using the three-dimensional circuit block. In addition, since the recess for heat insulation of the heat detection element is directly formed in the second resin layer, the number of parts can be reduced and the cost can be reduced, and the circuit board for mounting the electronic circuit elements can be fine. A circuit board can be made into a multilayer board structure that can be easily manufactured by pressing using a printed board or a board using a thin copper foil that can form a fine pitch circuit by a general circuit board forming method. In addition, since the terminal pin is electrically connected to the circuit block on the mounting surface of the heat detection element, the connection between the heat detection element and the circuit block (mounting the heat detection element on the circuit block), the terminal pin and the circuit block, Can be performed in the same process, the number of processes can be reduced, and inspection of each bonding state can be performed by visual inspection, which facilitates the inspection in the manufacturing process and reduces the manufacturing cost. It can be reduced (low cost can be achieved). Further, by interposing a shield layer between the first resin layer and the second resin layer, it is possible to prevent noise generated in the electronic circuit element from being superimposed on the detection output of the heat detection element. .

  Furthermore, the circuit block is housed in a metal package composed of a stem and a cap, the cap window hole is closed with a conductive filter, and the filter and the cap are electrically connected. In addition to reducing the effects of noise, it is possible to suppress capacitive coupling between the heat detection element and the terminal pin via the space in the package, and a conductive pattern for shielding is provided on the mounting surface. Therefore, capacitive coupling between the heat detection element and the terminal pin can be further suppressed, detection sensitivity can be prevented from being deteriorated, and noise resistance can be improved.

  According to a second aspect of the invention, in the first aspect of the invention, the conductor pattern is formed to surround the terminal pin except for the side opposite to the heat detection element side of the terminal pin. To do.

  According to the invention of claim 2, since the conductor pattern is provided between the terminal pin and the heat detection element that need the most shielding, the conductor pattern is reduced while suppressing the deterioration of the shielding performance of the conductor pattern. Space saving of the part to be arranged can be achieved, the circuit block can be reduced in size, and the terminal pin and the circuit block can be connected on the side opposite to the heat detection element side of the terminal pin not provided with the conductor pattern. The terminal pin and the conductor pattern can be prevented from being short-circuited by a conductive adhesive or the like used for this connection.

  According to a third aspect of the invention, in the first or second aspect of the invention, the potential of the conductor pattern is a ground potential.

  According to the invention of claim 3, since it is only necessary to connect the conductor pattern to the ground that is most often used on the circuit, the wiring work of the conductor pattern is easy, and capacitive coupling can be prevented.

  According to a fourth aspect of the present invention, in the first or second aspect of the invention, the potential of the conductor pattern is a predetermined constant potential.

  According to the invention of claim 4, capacitive coupling can be prevented.

  According to a fifth aspect of the present invention, in the first or second aspect of the present invention, the potential of the conductor pattern is a reference potential for the heat detection element.

  According to the invention of claim 5, since capacitive coupling can be prevented and the electrode for applying the reference potential to the heat detection element is formed on the mounting surface of the circuit block, the same mounting surface Can be easily connected to the conductor pattern formed on the substrate.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the thermal detection element comprises a plurality of sensing elements formed by sandwiching a pyroelectric body between a detection electrode and a reference potential electrode. And the sensing element closest to the terminal pin among the plurality of sensing elements is characterized in that the reference potential electrode is located on the side opposite to the second resin layer side with respect to the pyroelectric body. To do.

  According to the invention of claim 6, it is possible to prevent the terminal pin and the detection electrode from being capacitively coupled by the space portion in the package.

  According to a seventh aspect of the present invention, in the invention according to any one of the first to fifth aspects, the thermal detection element comprises a plurality of sensing elements formed by sandwiching a pyroelectric body between a detection electrode and a reference potential electrode. And the sensing element closest to the terminal pin among the plurality of sensing elements is characterized in that the reference potential electrode is located on the second resin layer side with respect to the pyroelectric body.

  According to the invention of claim 7, it is possible to prevent the terminal pin and the detection electrode from being capacitively coupled by the second resin layer.

  The invention of claim 8 is characterized in that, in the invention of any one of claims 1 to 7, the conductor pattern is covered with an insulating portion.

  According to invention of Claim 8, it can prevent that a terminal pin and a conductor pattern short-circuit by the conductive adhesive etc. which are used for the connection of a terminal pin and a circuit block.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the conductor pattern is formed around a terminal pin for detection signal output of the drive circuit. .

  According to the ninth aspect of the present invention, capacitive coupling between the heat detection element and the detection signal output terminal pin can be prevented by the shielding effect of the conductor pattern, and as a result, sensitivity deterioration can be prevented and noise resistance can be improved. . In particular, the detection signal output terminal pin has a great influence on the heat detection element due to capacitive coupling. Therefore, by preventing capacitive coupling between the detection signal output terminal pin and the heat detection element, further deterioration in sensitivity can be prevented. Can be planned.

  In the present invention, since the electronic circuit element is embedded in the first resin layer, there is an effect that it can be significantly reduced in size and thickness as compared with the conventional example using the three-dimensional circuit block. Since the capacitive coupling between the heat detection element and the terminal pin can be suppressed by the shield conductor pattern, the detection sensitivity can be prevented from being deteriorated, and the noise resistance can be improved.

  In addition to the effects described above, the present invention can reduce the number of parts and reduce the cost by forming a recess for heat insulation of the heat detection element directly in the second resin layer. A multilayer substrate structure that can be easily manufactured by pressing can be obtained, and bonding of the heat detection element and the circuit block (mounting of the heat detection element to the circuit block) and bonding of the terminal pin and the circuit block are performed in the same process. The number of processes can be reduced, inspection of each joining state can be performed by visual inspection, the inspection in the manufacturing process becomes easy, and the cap of the circuit block 3 is stored in the metal package. Since the window hole is closed with a conductive filter and the filter and the cap are electrically connected, the influence of external noise can be reduced, and the filter is interposed between the first resin layer and the second resin layer. The shielding layer in which an effect that noise generated by the electronic circuitry can be prevented from being superimposed on the detection output of the thermal detection element.

  As shown in FIGS. 1A to 1C, an infrared detector A according to an embodiment of the present invention is an electronic circuit that constitutes a heat detection element 1 and a drive circuit for the heat detection element (see FIG. 5). A metal block comprising a circuit block 3 having elements (chips), a stem 4 to which the circuit block 3 is fixed, and a cap 5 attached to the stem 4 so as to house the circuit block 3 And package. In the following description, for simplification of description, the side on which the circuit block 3 is attached in the stem 4 (upper side in FIG. 1A) is defined as the upper side of the infrared detector A.

As shown in FIGS. 2 and 3, the heat detection element 1 includes a plurality (four in this embodiment) of sensing elements 1 a formed by sandwiching a pyroelectric body 10 between a detection electrode 11 and a reference potential electrode 12. It has a so-called quad type. In the following description, to distinguish the four sensing elements 1a, represented by reference numeral _1a 1 to 1A ₄ as necessary.

The pyroelectric body 10 is formed in a substantially square plate shape by a pyroelectric material (for example, PZT), and two detection electrodes 11 and two reference potential electrodes 12 are provided on both surfaces in the thickness direction. Is formed. The two detection electrodes 11 and the two reference potential electrodes 12 are arranged in a 2 × 2 matrix, and the same type of electrodes 11 and 12 are positioned on the diagonal line of the pyroelectric body 10 (FIG. 2). In (a), the detection electrode 11 is located on the upper left and lower right, and the reference potential electrode 12 is located on the lower left and upper right). 2A and 2B, the detection electrode 11 on the one side in the thickness direction of the pyroelectric body 10 includes a reference potential electrode 12 on the other side in the thickness direction and a reference potential electrode 12 on the other side in the thickness direction. The detection electrode 11 is provided so as to overlap with the reference potential electrode 12 on one side in the thickness direction in the thickness direction. In the heat detection element 1 of the present embodiment, in the sensing elements 1a ₁ and 1a ₄ , as shown in FIG. 3A, the detection electrode 11 is on the upper side of the pyroelectric body 10, and the reference potential electrode 12 is As shown in FIG. 3B, in the sensing elements 1a ₂ and 1a ₃ located below the pyroelectric body 10, the detection electrode 11 is below the pyroelectric body 10, and the reference potential electrode 12 is pyroelectric. It is located on the upper side of the electric body 10.

  A detection terminal 13 connected to the detection electrode 11 is formed on one side of each side of the pyroelectric body 10 in the thickness direction (the left side in FIGS. 2A and 2B), and is opposite to the one side. A reference potential terminal 14 connected to the reference potential electrode 12 is formed on the other side (the right side in FIGS. 2A and 2B). The electrodes 11 and 12 and the terminals 13 and 14 are formed by sputtering or the like. 2 and FIG. 11, the illustration of the electrodes 11 and 12 and the terminals 13 and 14 is omitted. Further, in FIG. 2B and FIG. 11B, in the thickness direction for simplification of illustration. The illustration of the electrodes 11 and 12 and the terminals 13 and 14 on the one surface side is omitted.

  In the heat detection element 1 in the present embodiment, four sensing elements 1 a are connected in parallel between the detection terminal 13 and the reference potential terminal 14. The heat detection element 1 is not limited to the one shown in the above example. For example, the heat detection element 1 is a so-called dual-type element in which a series circuit composed of two sensing elements 1a is connected in parallel, or two sensing elements 1a. It may be a thing. As the heat detection element 1, in addition to the one using a pyroelectric material, one using a thermopile or a bolometer can be adopted.

  As shown in FIG. 4, the circuit block 3 includes a circuit board 30 formed in a disk shape having an outer diameter similar to the outer diameter of the mounting portion 4a of the stem 4 described later using a glass epoxy board or the like. ing. The circuit board 30 has a chip-like electronic component 20 to be an electronic circuit element mounted on one side in the thickness direction (upper surface side in FIG. 2), and an electronic circuit on the other side in the thickness direction (lower surface side in FIG. 2). An integrated circuit (hereinafter abbreviated as “IC”) 21 serving as an element is mounted, and a drive for the heat detection element 1 is provided on each of both sides in the thickness direction of the circuit board 30 together with the electronic circuit elements described above. A wiring pattern (not shown) for forming a circuit is formed. The chip-shaped electronic component 20 is mounted on the circuit board 30 by reflow soldering or the like, and the IC 21 is mounted on the circuit board 30 by flip chip mounting.

  As shown in FIG. 5, the drive circuit generates a reference potential (2 V in this embodiment) to be applied to the reference potential electrode 12 of the heat detection element 1 and detects the detection output of the heat detection element 1 (with respect to the ground level). (A detection output having a level in either positive or negative direction), a band-pass filter 30b for removing a noise component from the output of the current amplification circuit 30a, and an output from the band-pass filter 30b A window comparator 30c that outputs a detection signal (see FIG. 10) composed of a voltage of “H” level or “L” level by comparing the level of the detected output to a predetermined threshold value. When performing human body detection, generally, a frequency response having a peak of about 1 Hz is given.

  A first resin layer 31 is provided on one side in the thickness direction of the circuit board 30, and the chip-shaped electronic component 2 mounted on one side in the thickness direction of the circuit board 30 is embedded in the first resin layer 31. Will be. A shield portion 32 is provided on the opposite side of the first resin layer 31 from the circuit board 30 side (stem 4 side).

  The shield portion 32 is obtained by forming a shield layer 32b on the surface (the upper surface in FIG. 4) of an insulating substrate 32a such as a circular glass epoxy substrate having the same size as the circuit board 30. More specifically, the shield part 32 insulates the shield layer 32b made of a metal foil (for example, a copper foil) for preventing an oscillation phenomenon caused by capacitive coupling between the detection output of the heat detection element 1 and the current amplification circuit 30a. It is formed on the surface of the substrate 32a (in this embodiment, it is formed on the upper surface in FIG. 4, but it may be formed on the lower surface or on both upper and lower surfaces). By having some specific potential, it acts as a shield. The shield layer 32b is formed so as to avoid a place where a through hole 3a and a through hole 3b described later are formed in the insulating substrate 32a. The shield part 32 is not limited to the shield layer 32b formed on the insulating substrate 32a, and the shield layer 32b may be formed directly on the first resin layer 31 by plating or the like.

  A second resin layer 33 is provided on the surface side of the shield part 32 (on the opposite side of the shield part 32 from the first resin layer 31 side). What is the shield part 32 side of the second resin layer 33? One surface on the opposite side is used as a mounting surface 33a on which the heat detection element 1 is mounted.

  As described above, the circuit block 3 in the present embodiment includes the first resin layer 31 laminated on the circuit board 30, the shield part 32 laminated on the first resin layer 31, and the shield part 32. A board unit having a multilayer structure composed of the second resin layer 33 is provided, and in this board unit, the chip-like electronic component 20 mounted on the circuit board 30 is embedded (embedded) in the first resin layer 31. Therefore, the entire circuit block 3 can be reduced in thickness.

  In such a board unit, through holes 3a through which three terminal pins (power supply terminal pins, ground terminal pins, detection signal output terminal pins) 6 are inserted are provided in the thickness direction. In addition, the pyroelectric element 1 (the detection terminal 13 and the reference potential terminal 14 of the pyroelectric element 1) and the through hole 3b for forming a through-hole wiring (not shown) for connecting the drive circuit to each other. Is provided. The substrate unit is provided with a through hole (not shown) for connecting the shield layer 32b of the shield part 32 to a predetermined potential site.

  As shown in FIGS. 1B and 6, an oblong hole-shaped recess 33 b is provided at the center of the mounting surface 33 a of the circuit block 3. Further, a land 33c connected to the detection terminal 13 of the heat detection element 1 and a land 33d connected to the reference potential terminal 14 are formed at both edges in the short direction of the recess 33b on the mounting surface 33a. Has been. Therefore, the heat detection element 1 is mounted on the mounting surface 33a so as to straddle the recess 33b in the short direction, and at this time, each sensing element 1a of the heat detection element 1 does not come into contact with the mounting surface 33a. ing. By this recess 33b, an air layer for thermal insulation is secured between the sensing element 1a serving as a heat ray detection part (light receiving surface) of the heat detection element 1 and the second insulating layer 33 of the circuit block 3, Highly sensitive measurement is possible. The lands 33c and 33d are connected to the through wirings in the corresponding through holes 3b, whereby the drive circuit and the heat detection element 1 are connected.

  By the way, land 33e for terminal pin joining is formed in the opening periphery of each penetration hole 3a in mounting surface 33a, respectively. The mounting surface 33a is provided with a conductor pattern 33f for shielding. The conductor pattern 33f has a land (lower land in FIG. 6) 33e corresponding to the detection signal output terminal pin 6 on the opposite side (lower side in FIG. 6) to the heat detection element 1 side in the land 33e. It is formed in a U-shape that is enclosed on three sides except for. The lands 33c to 33e and the conductor pattern 33f are not shown in FIG.

Next, a method for manufacturing the circuit block 3 described above will be briefly described with reference to FIG. First, as shown in FIG. 7A, the first resin layer 31 is formed on one surface in the thickness direction (the upper surface in FIG. 7A) of the circuit board 30 on which the chip-shaped electronic component 20 has been mounted in advance. A plurality of (three in the illustrated example) organic green sheets 34 serving as a base are stacked and arranged. Here, the organic green sheet 34 is the same as the circuit board 30 made by highly filling (for example, 85 wt%) an inorganic filler such as silica (SiO ₂ ) into a thermosetting resin such as an epoxy resin in a B stage (semi-cured) state. It is formed into a circular sheet of size, has high elongation and tensile strength, and has the characteristics of being tough and difficult to break at room temperature. In addition to the epoxy resin, a phenol resin, a cyanate resin, or the like can be used as the thermosetting resin. In addition to silica, aluminum oxide (Al ₂ O ₃ ), magnesium oxide ( MgO), boron nitride (BN), or a mixture of two or more of these can be used.

  After the organic green sheet 34 that is the basis of the first resin layer 31 is overlaid on the circuit board 30, the shield part 32 is placed on the organic green sheet 34, and then the second part is placed on the shield part 32. A plurality (two in the present embodiment) of organic green sheets 34 serving as the basis of the resin layer 33 are arranged to overlap. Here, in order to prevent capacitive coupling by the second resin layer 33, it is effective to reduce the thickness of the second resin layer 33, and in general, it is preferable to set the thickness to 0.3 mm or less. The thickness and number of the organic green sheets 34 are set so that the collection of the second resin layers 33 is 0.3 mm or less.

  As described above, the organic green sheet 34 that is the basis of the first resin layer 31, the shield portion 32, and the organic green sheet 34 that is the basis of the second resin layer 33 are sequentially stacked on the circuit board 30. The body is put into a press mold, and then heated while being evacuated (for example, 100 ° C.) to thermally dissolve the organic green sheet 34, and pressurized at a predetermined pressure (for example, 3 Mpa) for a certain time. At this time, the dissolved organic green sheet 34 flows into the unevenness of the chip-shaped electronic component 20 on the circuit board 30 and the gap between the electronic component 20 and the circuit board 30. After pressurizing for a certain period of time, the temperature is raised to a predetermined temperature (the curing temperature of the thermosetting resin constituting the organic green sheet 34, in the case of an epoxy resin, 175 ° C.) and completely cured.

  As a result, as shown in FIG. 7B, the first resin layer 31 containing the chip-like electronic component 20 is formed integrally with the circuit board 30, and the circuit board 30 side of the first resin layer 31 is formed. The second resin layer 33 is integrally formed on the side opposite to the first layer, and a shield portion 32 (shield layer 32a) is interposed between the first resin layer 31 and the second resin layer 33. That is, the first resin layer 31 in which the chip-like electronic component 20 that is a part of the electronic circuit element 2 is embedded, and the shield layer 32b on the opposite side of the first resin layer 31 from the stem 4 side are provided. The circuit block 3 having the second resin layer 33 provided therebetween is obtained. In addition, if the convex part (not shown) for forming the recess 33b is provided in the metal mold | die of a press, the recess 33b can be formed simultaneously.

  As described above, after the circuit board 30, the first resin layer 31, the shield part 32, and the second resin layer 32 are integrated, the through hole 3a and the through hole 3b are formed using a router or the like. The After that, a conductive layer (not shown) is formed on the mounting surface 33a by electroless plating or the like, and through hole plating for interlayer connection (for through hole wiring) is applied to the inner surface of the through hole 3a and the through hole 3b. After the plating, a part of the conductive layer is removed using a photolithography technique, an etching technique, and the like to form lands 33c to 33e, a conductor pattern 33f, and the like, thereby obtaining the configuration shown in FIG.

  The stem 4 is formed in a disk shape from a metal material (for example, SPC or Kovar). The central portion of the stem 4 protrudes from the peripheral portion to one surface in the thickness direction (the upper side in FIG. 1A), and this protruding central portion is the mounting portion 4a on which the circuit block 3 is mounted. A plurality (three in this embodiment) of insertion holes 4b through which the terminal pins 6 are inserted are formed in the mounting portion 4a. The terminal pin 6 is for electrically connecting a drive circuit of the circuit block 3 housed in the package and an external circuit, and is made of a conductive material, and the first resin layer 31 side in the stem 4 It is formed in the shape of a round bar that can penetrate between the opposite surface (the lower surface in FIG. 1A) and the mounting surface 33a. In the infrared detector A of the present embodiment, a power supply terminal pin 6 (hereinafter, indicated by reference numeral 6A if necessary), a ground terminal pin 6 (hereinafter, indicated by reference numeral 6B, if necessary), , Three terminal pins 6 with detection signal output terminal pins 6 (hereinafter, indicated by reference numeral 6C if necessary) are used.

  By the way, the inner diameter of the insertion hole 4b corresponding to the terminal pin 6B is set to be slightly larger than the outer diameter of the terminal pin 6B. After the terminal pin 6B is inserted into the insertion hole 4b, the terminal pin 6B is made of a conductive adhesive ( It is fixed to the stem 4 using a conductive paste such as silver paste) and is electrically connected to the stem 4. On the other hand, the insertion holes 4b corresponding to the terminal pins 6A and 6C are set to have larger inner diameters than the insertion holes 4b corresponding to the terminal pins 6C, and the terminal pins 6A and 6C are inserted into the corresponding insertion holes 4b. In this state, the terminal pins 6A and 6C are electrically insulated from the stem 4 by sealing the gap between the terminal pins 6A and 6C and the insertion hole 4b with an insulating sealing material 7 such as glass. Then, it is fixed to the stem 4.

  As shown in FIG. 1A, the circuit block 3 is attached to the stem 4 with a spacer 8 interposed between the circuit block 3 and the stem 4. The spacer 8 is for securing a space for accommodating the IC 21 mounted on the circuit board 30 between the circuit block 3 and the stem 4. Such a spacer 8 is a resin molded product made of an insulating resin material, and is formed in a disk shape. A substantially rectangular opening 8a is formed at the center of the spacer 8, and the IC 21 mounted on the circuit board 30 is accommodated in the opening 8a. Further, the spacer 8 is provided with insertion holes 8b through which the terminal pins 6 are inserted in the thickness direction.

  The cap 5 is formed in a circular box shape (cylindrical shape with one open end closed) having one surface in the thickness direction (the lower surface in FIG. 1A) opened by a metal material (for example, SPC or Kovar). Yes. The inner diameter of the cap 5 is slightly larger than the outer diameter of the central portion of the stem 4, whereby the mounting portion 4 a of the stem 4 is inserted into the cap 5. The circuit block 3 is housed in a space surrounded by the cap 5 and the stem 4.

  A rectangular window hole 5a is opened at the center of the other wall portion in the thickness direction of the cap 5 (the upper wall portion in FIG. 1A). The window hole 5a is for taking light into the package (for lighting), and is formed in a size that allows the heat detection element 1 to face the outside of the cap 5. A circular flange 5b is formed at the opening edge of the cap 5 on the one surface side in the thickness direction. The outer diameter of the flange portion 5 b is approximately the same as the outer diameter of the stem 4, and when the cap 5 is attached to the stem 4, the flange portion 5 b comes into contact with the peripheral portion of the stem 4.

  A filter 9 is attached to such a cap 5 so as to close the window hole 5a. The filter 9 is a band-pass optical filter that transmits only infrared rays in a specific frequency range. When the use of the infrared detector A is human detection, the filter 9 has a wavelength of about 4 μm or more. The one that transmits the light of the above and cuts infrared rays having a shorter wavelength than that is used. The filter 9 is formed using a conductive material, for example, a semiconductor (for example, a low-resistance silicon substrate doped with impurities) or a conductor. The filter 9 is joined to the cap 5 using a conductive adhesive (for example, a silver paste) so as to be electrically connected to the cap 5. That is, a filter 9 made of a conductive material and transmitting infrared rays is attached to the cap 5 so as to close the window hole 5a and to be electrically connected to the cap 5. Note that an electrode (not shown) that is ohmically connected to the filter 9 may be provided, and the filter 9 and the cap 5 may be electrically connected by electrically connecting the electrode and the cap 5.

  The circuit block 3 is housed in the package including the stem 4 and the cap 5 as follows.

  That is, the circuit block 3 is mounted on the mounting portion 4a of the stem 4 via the spacer 8, and the circuit block 3 and the spacer 8, and the spacer 8 and the mounting portion 4a are joined with an adhesive or the like. At this time, the IC 21 is accommodated in the opening 8 a of the spacer 8.

  The terminal pin 6 passes through the insertion hole 8 b of the spacer 8 and the insertion hole 3 a of the circuit block 3, and one end thereof (the upper end portion in FIG. 1A) protrudes from the mounting surface 33 a of the circuit block 3. It will be.

After the circuit block 3 is mounted and fixed on the stem 4, the heat detection element 1 is bridged between the lands 33 c and 33 d on both sides of the recess 33 b of the second resin layer 33, and in this state, the heat detection element 1 is used for detection. The terminal 13 is connected to the land 33c and the reference potential terminal 14 is connected to the land 33d by a conductive adhesive (the heat detecting element 1 is mounted on the mounting surface 33a so as to straddle the heat insulating recess 33b). . At this time, as shown in FIG. 3B, the heat detection element 1 has the reference potential electrode 12 on the side opposite to the second resin layer 33 side (that is, the filter 9 side) with respect to the pyroelectric body 10. The located sensing element 1a is arranged so as to be located at a position closest to the detection signal output terminal pin 6C among the plurality of sensing elements 1a. In the illustrated example, the sensing element 1a ₄ is closest to the terminal pin 6C for the detection signal output.

  Simultaneously with the mounting operation of the heat detection element 1, the tip portions of the terminal pins 6 protruding on the mounting surface 33 a of the second resin layer 33 are formed on the lands 33 e on the peripheral edge of the through hole 3 a by the conductive adhesive 35. The terminal pins 6 and the circuit block 3 are electrically connected to each other.

  As described above, the detection terminal 13 of the heat detection element 1 passes through the land 33c and the through hole wiring of the through hole 3b, and the reference potential terminal 14 passes through the land 33c and the through hole wiring of the through hole 3b. Each terminal pin 6 is connected to the drive circuit of the circuit block 3 via the through hole wiring of the through hole 3a, and the circuit configuration shown in FIG. 5 is obtained. In the infrared detector A, the operation power is supplied from the outside via the power supply terminal pin 6A and the ground terminal pin 6B, and the detection signal output terminal pin 6C and the ground terminal pin are supplied. With 6B, it becomes possible to output a detection signal to the outside.

  After the joining of the heat detection element 1 and the terminal pin 6 is finished, the joining state is visually inspected, and then the cap 5 is attached to the stem 4. The cap 5 is attached to the stem 4 such that the mounting portion 4 a of the stem 4 enters the cap 5 and the flange portion 5 b abuts on the peripheral portion of the stem 4. The cap 5 is fixed to the stem 4 by welding the flange portion 5b to the peripheral portion of the stem 4, thereby hermetically sealing the inside of the package. In this way, the infrared detector A shown in FIG. 1C is obtained.

  According to the infrared detector A of the present embodiment described above, since the chip-like electronic component 20 of the electronic circuit element 2 is embedded in the first resin layer 31, it becomes an obstacle to downsizing in the standing direction. Since a space (mounting area) for mounting the electronic circuit element 2 that has been used can be secured, the size and thickness can be significantly reduced as compared with the conventional example using the three-dimensional circuit block 100 (see FIG. 14). Can be achieved.

  In addition, since the recess 33b for heat insulation of the heat detection element 1 is directly formed in the second resin layer 33, the number of parts can be reduced and the cost can be reduced, and the electronic circuit element 2 is mounted. A circuit board 30 having a multilayer board structure that can easily manufacture a circuit block 3 by pressing using a printed board that can form a fine fine pitch circuit by a general circuit board forming method or a board that uses a thin copper foil. can do.

  Further, since the terminal pin 6 is electrically connected to the circuit block 3 on the mounting surface 33a of the heat detection element 1, the junction between the heat detection element 1 and the circuit block 3 (mounting of the heat detection element 1 to the circuit block 3). ) And the terminal pin 6 and the circuit block 3 can be joined in the same process, the number of processes can be reduced, and inspection of each joined state can be performed by visual inspection. Inspection can be facilitated, and the manufacturing cost can be reduced (low cost can be achieved).

  In addition, noise generated in the electronic circuit element 2 is superimposed on the detection output of the heat detection element 1 by interposing the shield layer 32b between the first resin layer 31 and the second resin layer 33. Can be prevented.

  Further, the circuit block 3 is housed in a metal package constituted by the stem 4 and the cap 5, the window hole 5 a of the cap 5 is closed with a conductive filter 9, and the filter 9 and the cap 5 are electrically connected. Since it is connected to (can be conducted), the influence of external noise can be reduced.

  When the terminal 6 protrudes from the mounting surface 33a as in the infrared detector A of the present embodiment, the heat detection element 1 and the terminal pin 6 are capacitively coupled through the space in the package. However, by using a conductive material as the filter 9 and electrically connecting the cap 5 and the filter 9, the capacitance of such capacitive coupling can be reduced.

  The graph shown in FIG. 8 is a graph showing the relationship between the distance t (see FIG. 9) between the filter 9 and the heat detection element 1 and the magnitude of the capacitance generated by capacitive coupling. It can be seen that the shorter the distance from 1, the less the influence of capacitive coupling.

  Here, if the capacitance due to capacitive coupling is 0.02 fF or less, as shown in FIG. 10A, chattering does not occur in the detection signal, but if the capacitance exceeds 0.02 fF, FIG. As shown in (b), chattering may occur in the detection signal.

  8A shows the case where there is no shield conductor pattern 33f, and B shows the case where the conductor pattern 33f is formed around the detection signal output terminal pin 6C as in this embodiment. As is apparent from the graph shown in FIG. 8, it can be seen that the capacitance of capacitive coupling can be reduced as a whole by providing the conductor pattern 33f.

  In the graph indicated by A in FIG. 8, chattering cannot be effectively prevented unless the distance between the filter 9 and the heat detection element 1 is suppressed to 0.4 mm or less. However, in the graph indicated by B in FIG. If the distance between 9 and the heat detection element 1 is suppressed to 0.9 mm or less, chattering can be effectively prevented.

  Therefore, by providing the conductor pattern 33f as in this embodiment, the capacitive coupling between the heat detection element 1 and the detection signal output terminal pin 6C can be further suppressed by the shielding effect of the conductor pattern 33f. Thus, it is possible to prevent sensitivity deterioration and improve noise resistance. In particular, since the detection signal output terminal pin 6C has a great influence on the heat detection element 1 due to capacitive coupling, the capacitive coupling between the detection signal output terminal pin 6C and the heat detection element 1 can be further suppressed. It is possible to prevent the deterioration of sensitivity.

  In the infrared detector A of the present embodiment, the conductor pattern 33f is formed to surround the terminal pin 6C except for the side opposite to the heat detection element 1 side of the terminal pin 6C. In this way, since the shielding conductor pattern 33f is provided between the terminal pin 6C and the heat detection element 1 that need the most shielding, the deterioration of the shielding performance of the conductor pattern 33f is suppressed. However, the space where the conductor pattern 33f is arranged can be saved, the circuit block 3 can be reduced in size, and the terminal pin 6C on which the conductor pattern 33f is not provided is connected to the terminal on the side opposite to the heat detection element 1 side. By connecting the pin 6C and the circuit block 3, it is possible to suppress a short circuit between the terminal pin 6C and the conductor pattern 33f due to a conductive adhesive or the like used for this connection.

  Furthermore, in the infrared detector A of the present embodiment, since the potential of the conductor pattern 33f is the reference potential for the heat detection element, capacitive coupling can be prevented by the conductor pattern 33f, and the heat detection element Since the land 33d serving as an electrode for applying a reference potential to 1 is formed on the mounting surface 33a of the circuit block 3, it can be easily connected to the conductor pattern 33f formed on the same mounting surface 33a. There are advantages.

In the present embodiment, among the plurality of sensing elements _1a 1 to 1A ₄ thermal detection element 1, closest to the sensing element 1a to the terminal pin 6C conductor pattern 33f is provided in the peripheral _4, to the pyroelectric 10 The reference potential electrode 12 is located on the side opposite to the second resin layer 33 side (that is, the filter 9 side). Therefore, the reference potential electrode 12 acts as a shield, and it is possible to prevent the terminal pin 6C and the detection electrode 11 from being capacitively coupled by the space in the package.

  By the way, as the heat detection element 1, what is shown to Fig.11 (a), (b) is employable. As in the case shown in FIG. 2, the heat detection element 1 shown in FIG. 11 includes a plurality of (four in the illustrated example) sensing elements in which the pyroelectric body 10 is sandwiched between the detection electrode 11 and the reference potential electrode 12. A so-called quad type having 1a, the arrangement positions of the detection electrode 11 and the reference potential electrode 12 are different from those shown in FIG.

That is, in the heat detection element 1 shown in FIG. 11, the positions of the detection electrode 11 and the reference potential electrode 12 are changed from those shown in FIG. 2 (in FIG. 11A, the reference is on the upper left and lower right). The potential electrode 12 is located, and the detection electrode 11 is located at the lower left and upper right. In FIG. 11B, the detection electrode 11 is located at the upper left and lower right, and the reference potential is located at the lower left and upper right. Electrode 12 is located). Therefore, in the heat detection element 1 shown in FIG. 11, in the sensing elements 1 a ₁ and 1 a ₄ , as shown in FIG. 3B, the detection electrode 11 is on the lower side of the pyroelectric body 10 and the reference potential electrode 12. Is located above the pyroelectric body 10, and in the sensing elements 1a ₂ and 1a ₃ , as shown in FIG. 3A, the detection electrode 11 is above the pyroelectric body 10 and the reference potential electrode 12 is pyroelectric. Located below the body 10.

Therefore, in the infrared detectors A using thermal detection element 1 shown in FIG. 11, the sensing element 1a ₄ closest to the terminal pin 6C conductor pattern 33f is provided around among the plurality of sensing elements 1a ₁ to 1A ₄ is The reference potential electrode 12 is located on the second resin layer 33 side (the opposite side of the pyroelectric body 10 from the filter 9 side) with respect to the pyroelectric body 10.

  In this case, the reference potential electrode 12 acts as a shield, and it is possible to prevent the terminal pin 6C and the detection electrode 11 from being capacitively coupled by the second resin layer 33.

  As shown in FIG. 12, the entire conductor pattern 33f may be covered with an insulating portion 33g made of a resist formed of an insulating material (for example, an epoxy resin). In this way, it is possible to prevent the terminal pin 6 and the conductor pattern 33f from being short-circuited by the conductive adhesive 35 used for the connection between the terminal pin 6 and the circuit block 3, and the assembly work is very easy. You can do it.

  In the infrared detector A of the present embodiment described above, the potential of the conductor pattern 33f is used as the reference potential of the heat detection element 1, but as shown in FIG. 13, the conductor pattern 33f is electrically connected to the ground terminal 6B. The conductor pattern 33f may be connected to the ground potential. In FIG. 13, only the configuration of the conductor pattern 33f is different from the above example, and the description thereof is omitted. In FIG. 13, the land 33e corresponding to the terminal pin 6C is omitted.

  If the potential of the conductor pattern 33f is set to the ground potential in this way, it is only necessary to connect the conductor pattern 33f to the ground that is most often used in the circuit. Therefore, the wiring work of the conductor pattern is facilitated and capacitive coupling is prevented. be able to. Further, when the ground potential is used, there is an advantage that there is no possibility of adversely affecting the heat detection element 1 as compared with the case where the reference potential of the heat detection element 1 is used.

  When it is difficult to set the potential of the conductor pattern 33f as a reference potential or a ground potential, a potential applying circuit (not shown) for applying a stable potential to the conductor pattern 33f is configured. By connecting the conductor pattern 33f to the potential applying circuit, the potential of the conductor pattern 33f may be set to a predetermined constant potential (stable potential) of the potential applying circuit. In this case as well, capacitive coupling can be suppressed. . In addition, when a potential applying circuit for applying a potential to the conductor pattern 33f is separately provided, such a potential applying circuit is provided in a place where the connection with the conductor pattern 33f is easily performed, so that the connection with the conductor pattern 33f can be achieved. Simplification can be achieved. Moreover, even if the conductor pattern 33f is not connected to any circuit, it can exhibit a shielding performance and suppress capacitive coupling.

  In the present embodiment, the conductor pattern 33f is provided around the detection signal output terminal pin 6C. However, the conductor pattern 33f may also be provided around other terminal pins 6. In addition, this embodiment is merely one form to which the technical idea of the present invention is applied, and is not intended to limit the present invention to this embodiment, and design changes and the like within a scope that does not depart from the spirit of the present invention. Of course you can.

The infrared detector of one Embodiment of this invention is shown, (a) is a disassembled perspective view, (b) is a perspective view of the state which removed the cap, (c) is a perspective view. The heat detection element in the same as above is shown, (a) is a top view, and (b) is a perspective view seen from the upper surface side. It is a fragmentary sectional view of the heat detection element same as the above. It is a schematic sectional drawing of the circuit block in the same as the above. It is a circuit block diagram same as the above. It is a top view in the state where the cap of the infrared detector same as the above was removed. It is explanatory drawing of the manufacturing process of the circuit block in the same as the above. It is a graph which shows the relationship between the distance of a heat detection element and a filter, and an electrostatic capacitance. It is explanatory drawing same as the above. It is a graph which shows the time change of a detection signal same as the above. The other example of the heat detection element same as the above is shown, (a) is a top view and (b) is a perspective view seen from the upper surface side. It is a top view in the state where the cap of the infrared detector of other examples same as the above was removed. It is a top view in the state where the cap of the infrared detector of other examples same as the above was removed. The infrared detector of a prior art example is shown, (a) is an exploded perspective view of a three-dimensional circuit block, (b) is a perspective view with a cap removed, and (c) is a perspective view.

Explanation of symbols

1 heat detecting element _{1a (1a} 1 ~1a 4) sensing element 2 electronic circuitry third circuit block 4 stem 5 cap 5a window hole 6 (6A, 6B, 6C) terminal pins 9 filter 10 pyroelectric 11 sensing electrode 12 reference Potential electrode 20 Electronic component 31 First resin layer 32b Shield layer 33 Second resin layer 33a Mounting surface 33b Recess 33f Conductor pattern 33g Insulation part A Infrared detector

Claims (9)

The circuit block is attached to the stem in such a manner that the circuit block is housed between the circuit block having the heat detection element and the electronic circuit element constituting the drive circuit for the heat detection element, and the stem to which the circuit block is attached. A metal package consisting of a cap,
The circuit block includes a first resin layer in which at least a part of an electronic circuit element is embedded, and a second resin layer provided on a side opposite to the stem side of the first resin layer via a shield layer. Have
A recess for heat insulation is formed on the mounting surface of the heat detection element consisting of one surface opposite to the shield layer side in the second resin layer,
The heat detection element is mounted on the mounting surface in a form straddling the recess for thermal insulation,
In the portion of the cap facing the heat detection element, a window hole for daylighting is formed,
The cap is an infrared detector that is made of a conductive material and transmits infrared rays, closes the window hole, and is attached to the cap in a conductive manner.
The terminal pin for electrically connecting the drive circuit of the circuit block housed in the package and the external circuit is provided so as to penetrate between the surface opposite to the first resin layer side of the stem and the mounting surface. Are electrically connected to the circuit block on the mounting surface,
An infrared detector, wherein a shielding conductor pattern is formed around a terminal pin on the mounting surface.   2. The infrared detector according to claim 1, wherein the conductor pattern is formed so as to surround the terminal pin except for a side opposite to the heat detection element side of the terminal pin.   The infrared detector according to claim 1, wherein the conductor pattern has a ground potential.   3. The infrared detector according to claim 1, wherein the conductor pattern has a predetermined constant potential.   3. The infrared detector according to claim 1, wherein the potential of the conductor pattern is a reference potential for the heat detection element. The heat detection element has a plurality of sensing elements in which a pyroelectric material is sandwiched between a detection electrode and a reference potential electrode,
The sensing element closest to the terminal pin among the plurality of sensing elements is characterized in that the reference potential electrode is located on the opposite side to the second resin layer side with respect to the pyroelectric body. The infrared detector according to any one of 1 to 5. The heat detection element has a plurality of sensing elements in which a pyroelectric material is sandwiched between a detection electrode and a reference potential electrode,
The sensing element closest to the terminal pin among the plurality of sensing elements has a reference potential electrode positioned on the second resin layer side with respect to the pyroelectric material. The infrared detector of any one of them.   The infrared detector according to claim 1, wherein the conductor pattern is covered with an insulating portion.   The infrared detector according to any one of claims 1 to 8, wherein the conductor pattern is formed around a terminal pin for detection signal output of the drive circuit.

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