JPH0628663U - Infrared detector holding structure - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an infrared detector that does not generate single noise due to temperature change and has high mounting accuracy. [Structure] There is a base 1 having lead terminals 31, 32 and 33, a substrate 5 is installed on the base 1, light receiving electrodes 10A and 10B are provided on the front surface, and a pair of back surface electrodes 12A and 12B are also provided on the back surface. The pyroelectric element 9 and the supports 81A and 81B supporting the pyroelectric element, and the circuit components 6 and 7 are mounted, and the cap 2 provided with the window on which the optical filter 4 is installed is provided on the base. In the infrared detector, which is covered with air and is hermetically sealed, the bonding area of each of the supports is narrower than the formation area of at least the one light-receiving electrode, and the focus area is formed from the formation area of each of the light-receiving electrodes. It was bonded to the back surface electrode in the region where the light was transmitted to the back surface side of the electric element at the shortest distance.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a holding structure for a detection element mounted on a pyroelectric infrared detector, and more particularly to a holding structure for a detection element in a pyroelectric infrared detector generally called a two-element type.

[0002]

[Prior art]

 The structure of a conventional pyroelectric infrared detector will be described with reference to the drawings. As shown in FIG. 3, the lead terminals 31, 32, and 33 are hermetically sealed and sealed in the through holes of the base 1 via glass. A printed wiring insulating substrate 5 is provided on the base 1, and circuit components such as the FET 6 and the resistor 7 and supports 8A and 8B made of metal pillars are mounted on the front and back surfaces thereof. Then, the pyroelectric element 9 which is a ceramic substrate having pyroelectricity, on which the light receiving electrodes 10A and 10B, the back electrodes 12A and 12B, and the connecting electrode 11 of the light receiving electrodes 10A and 10B are formed, is formed at both ends of the pyroelectric element. Then, it is fixed on the support with a conductive bonding material. The base 1 configured as described above is covered with the cap 2 provided with the window having the optical filter 4 to hermetically seal it.

[0003]

[Problems to be solved by the device]

 However, since both ends of the pyroelectric element 9 are fixedly joined to the supports 8A and 8B, as shown in FIG. 4, when the pyroelectric element is mounted on the support, the pyroelectric element may be displaced. Thus, the contact regions 13A and 13B between the pyroelectric element 9 and the supports 8A and 8B have different areas depending on the left and right supports. Therefore, a difference occurs between the thermal conductivity of the support 8A and the light-receiving electrode 10A and the thermal conductivity of the support 8B and the light-receiving electrode 10B, which causes variations in sensitivity between the left and right pyroelectric elements, and a single noise caused by a temperature change. May occur.

[0004]

Therefore, the holding structure for an infrared detection element of the present invention has a base having a plurality of electrically independent lead terminals, and a printed wiring board is provided above the base. When installed, a pair of light-receiving electrodes is provided on the front surface, and a pair of back surface electrodes is also provided on at least the back surface, which is a facing surface, and at least two pyroelectric elements that support the pyroelectric element. A support and circuit parts are mounted, a cap is placed on the base to make it airtight, a window is provided on the top of the cap, and an optical filter that transmits infrared rays of a desired wavelength is installed in this window. In the infrared detector, the joint area of each support is narrower than at least one light receiving electrode forming area, and the pyroelectric area is formed from each of the light receiving electrode forming areas. Was bonded to the back surface electrode in the region is transmitted through the shortest distance to the rear surface side of the child.

[0005]

[Action]

 The bonding area of each support is narrower than the area where each light-receiving electrode is formed, and the area where each light-receiving electrode is formed is the shortest distance (vertical) to the back side of the pyroelectric element. Since it is bonded to the back electrode of the support, the contact area between the pyroelectric element and the support does not differ between the left and right supports even if the pyroelectric element is slightly displaced when mounted on the support. The contact area of the same area is obtained at, and the thermal conductivity between the left support and the left light receiving electrode is equal to the thermal conductivity between the right support and the right light receiving electrode.

[0006]

【Example】

 Next, the present invention will be described with reference to the drawings. FIG. 1 is a front view of a perspective view showing an embodiment of the present invention, and FIG. 2 is a plan view before sealing the cap of FIG. It should be noted that the same numbers are assigned to the same parts as the conventional ones. The pyroelectric element 9 is made of lead titanate-based pyroelectric ceramic, is polarized in the plate thickness direction, and is cut into a rectangular shape. The pyroelectric element 9 is generally called a two-element type and has the following electrode configuration. That is, the front surface is provided with metal film electrodes (Cr or Ni-Cr or the like) 10A and 10B for light reception at predetermined intervals by means such as vapor deposition, and the back surface is provided with the metal film electrodes (Ag or the like) 12A. , 12B are provided. The light-receiving electrodes 10A and 10B are commonly connected by a connecting electrode (Cr or Ni-Cr) 11. The base 1 is made of metal, and an insulating substrate 5 having a printed wiring is installed on the upper part thereof, and on the front and back surfaces thereof, an FET 6 constituting an external circuit, an electronic component 7 such as a resistor, and a pyroelectric element 9 are supported to support a metal pillar or the like. Supports 81A and 81B made of are mounted and necessary connections are made. Further, the joint portions of the supports 81A and 81B with the pyroelectric element are formed so as to be narrower than the vertical and horizontal widths of the light receiving electrodes 10A and 10B of the pyroelectric element, and on the electrodes 12A and 12B, In addition, an electrically and mechanically joined to the pyroelectric element 9 by a conductive joining material in a region which is vertically transmitted from the region where the light receiving electrode is formed to the back surface side of the pyroelectric device. Further, the base 1 has a plurality of lead terminals 31, 32, 33 which are electrically independent of each other, and are hermetically and electrically insulated and sealed in the through holes of the base 1 via glass. An infrared radiation window is provided near the center of a cap 2 that seals each of these components, and an optical filter 4 that transmits only infrared radiation in a specific wavelength region is attached below the infrared radiation window. This is because the pyroelectric element is not wavelength-dependent in sensitivity, and it is necessary to select a desired wavelength region in advance. Then, the cap 2 and the base 1 are hermetically sealed.

Next, dimensional examples of the pyroelectric element 9, the support (81A, 81B), and the electrodes (10A, 10B, 11, 12A, 12B) in this embodiment are shown in FIG. 5, FIG. 6, and FIG. Let me explain with reference. The pyroelectric element 9 has a longitudinal dimension (l₀) Is 5.2 mm, and the dimension in the lateral direction (w₀) Is 3.8 mm, and the surface of the pyroelectric element 9 is 1.1 mm inward (l) from both ends of the pyroelectric element in the longitudinal direction.₃ , l_Four), Which is 0.9 mm inward from both ends in the lateral direction of the pyroelectric element (w₂, W₃), Vertical (w₁) 2 mm wide (l₁, L ₂ ) 1 mm light receiving electrodes 10A and 10B are formed, and the width (w) is provided between the light receiving electrodes 10A and 10B._Four) A connecting electrode 11 of 0.2 mm is formed. Then, on the back side, 2.1 mm inward from each end of the pyroelectric element in the longitudinal direction (l_Five, L₆), Rear surface electrodes 12A and 12B are formed on the entire surface. The supports 81A and 81B are formed to have a length (L) of 1.5 mm, a width (W) of 0.5 mm, and a height (H) of 0.6 mm. Further, the pyroelectric element 9 and the supports 81A and 81B described above are arranged in the region {w₁× l₁(Length 2mm, width 1mm), w₁× l₂(2 mm in length, 1 mm in width)} is in a region vertically transmitted to the back surface side of the pyroelectric element, and is electrically connected to the pyroelectric element 9 by a conductive bonding material on the back surface electrodes 12A and 12B. Mechanically and mechanically joined. That is, the mountable areas 15A and 15B on the back surface electrode (1.1 mm inward from both longitudinal ends of the back surface of the pyroelectric element and 0.9 mm inward from both lateral ends of the back surface of the pyroelectric element). The support may be joined to the pyroelectric element in a region of 2 mm in length and 1 mm in width of the side portion). Therefore, even if the pyroelectric element is slightly displaced when mounted on the support, the contact areas 14A and 14B between the pyroelectric element 9 and the support (81A and 81B) shown in FIG. To be

[0008]

[Effect of device]

 According to the present invention, the contact area between the pyroelectric element and the supporting body does not differ between the left and right supporting bodies even when the pyroelectric element is displaced when mounted on the supporting body. The thermal conductivity between the support on the left side and the light receiving electrode on the left side and the thermal conductivity between the support on the right side and the light receiving electrode on the right side became equal, and the sensitivity did not fluctuate between the left and right pyroelectric elements. In addition, single noise due to temperature change is no longer generated. For this reason, a highly reliable pyroelectric infrared detector can be obtained, and since there is no problem even if there is some misalignment, it is possible to obtain a pyroelectric element that has high mounting accuracy and is suitable for automatic machines.

[Brief description of drawings]

FIG. 1 is a perspective front view showing an embodiment of the present invention.

FIG. 2 is a plan view before sealing the cap of FIG.

FIG. 3 is a perspective front view showing a conventional example.

FIG. 4 is a plan view in the case where a shift occurs in the element in the embodiment before sealing the conventional cap.

FIG. 5 is a plan view of the device of the present invention.

FIG. 6 is a perspective view of a support according to the present invention.

FIG. 7 is a bottom view of the device of the present invention.

[Explanation of symbols]

 1 ... Base 2 ... Cap 31, 32, 33 ... Lead terminal 4 ... Filter 5 ... Insulating substrate 6 ... FET 7 ... Resistor 8A, 8B, 81A, 81B ... Support 9 ... Pyroelectric element 10A, 10B ... Light receiving electrode 11 ... Connection electrode 12A, 12B ... Back surface electrode 13A, 13B, 14A, 14B ... Contact area 15A, 15B ... Mountable area

Claims (1)

[Scope of utility model registration request] 1. A base having a plurality of electrically independent lead terminals is provided, a printed wiring board is provided on the base, and a pair of light receiving electrodes is provided on the surface, and A pyroelectric element provided with a pair of back surface electrodes on at least the back surface, which is the opposite surface, and at least two supports for supporting the pyroelectric element, and a circuit component are mounted, and a cap is placed on the upper part of the base. In an infrared detector, which is hermetically sealed with a window provided on the upper surface of the cap, and an optical filter for transmitting infrared rays having a desired wavelength is installed in the window, the bonding region of each of the supports is at least the It is made narrower than the area where one light-receiving electrode is formed, and is bonded to the back surface electrode in the area that is transmitted from the area where each light-receiving electrode is formed to the back surface side of the pyroelectric element in the shortest distance. Characteristic infrared detector holding structure.