JPH07280653A - Infrared detector - Google Patents

Abstract

PURPOSE:To provide a more reliable infrared detector with a higher manufacturing efficiency while enhancing the electromagnetic shielding effect of the case. CONSTITUTION:The infrared detector comprises an infrared detector element 9, a metallic case 2 therefor having a window 21 passing the infrared rays, and an optical filter 4 transmitting the infrared rays. The optical filter 4 comprises a semiconductor substrate coated, on the opposite major surfaces thereof, with an optical filter film transmitting an infrared ray of desired wavelength. The optical filter film is at least partially stripped from a part where the optical filter 4 is joined to the case thus exposing the semiconductor substrate at the thin part. The thin part of the optical filter 4 is then coated with a conductive bonding material and bonded electrically to the case 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared detector, particularly a pyroelectric element, which is used for non-contact temperature detection and human body detection.

[0002]

2. Description of the Related Art The structure of a conventional pyroelectric infrared detector will be described with reference to the drawings. As shown in FIGS. 9 and 10, the plurality of lead terminals 31 and 32 are hermetically and insulatively sealed to the through holes of the base 1 via glass. A printed wiring insulating substrate 5 is installed on the base 1, and circuit components such as the FET 6 and the resistor 7 and supports 8A and 8B made of metal columns are mounted on the front and back surfaces of the insulating substrate 5. Then, the light receiving electrodes 10A and 10B, the back surface electrode 12
A, 12B, connecting electrode 1 of the light receiving electrodes 10A, 10B
The pyroelectric element 9, which is a ceramic substrate having pyroelectricity in which 1 is formed, is fixed to the support body by a conductive bonding material at both ends of the pyroelectric element. The metallic cap 2 for sealing the above-described components has a window 21 on its upper part and an optical filter 4 for transmitting infrared rays. The optical filter 4 is, for example, a semiconductor substrate 4 made of silicon or the like.
An optical filter film 42 that transmits infrared rays having a desired wavelength is formed on both main surfaces of No. 1. Electromagnetic noise generated from other electronic components on the circuit board is also absorbed by these optical filters 4. Therefore, as a countermeasure against these electromagnetic noises, the exposed portion 41a of the semiconductor substrate 41 or the optical filter 4 at the cut surface of the optical filter 4 is prevented. After electrically connecting the cap 2 to the portions 41b and 41c of the optical filter film 42 of No. 4 where the semiconductor substrate 41 is exposed by shaving the portion to be joined to the cap 2 with the conductive joining material 13, The upper part is mechanically bonded by the bonding material 14 and attached to the window 21 of the cap 2. Then, the cap 2 is placed on the base 1 to hermetically seal it.

[0003]

However, in the conduction between the exposed portion 41a of the semiconductor substrate 41 and the cap 2 on the cut surface of the optical filter 4 formed by the conductive bonding material, the coating state of the bonding material and the conductive bonding material is used. Due to this, the conductivity with the exposed portion 41a is likely to vary, and perfect conduction may not be ensured. In addition, in the conduction of the portions 41b and 41c of the optical filter film 42 of the optical filter 4 made of a conductive bonding material, in which the bonding portion with the cap 2 is shaved to expose the semiconductor substrate 41, as shown in FIG. In some cases, the method of shaving the film 42 was liable to vary, and perfect conduction could not be ensured. For these reasons, electromagnetic noise cannot be completely grounded and is detected by the element, causing malfunction. Therefore, there is a problem in reliability as a shield structure for electromagnetic noise. In order to simplify the process, there is a method of applying the conductive bonding material first and then hardening the conductive bonding material before hardening. When the material and the material are used, the respective bonding materials may be dispersed, the conductivity of the conductive bonding material may be reduced, and it may not be possible to sufficiently secure conduction between the optical filter and the cap. Therefore, similarly to the above-described case, the electromagnetic noise cannot be completely grounded and is detected by the element, which causes a malfunction. Therefore, there is a problem in reliability as a shield structure for electromagnetic noise.

An object of the present invention is to provide a more reliable infrared detector having an improved electromagnetic shielding effect of the case and having high manufacturing efficiency.

[0005]

Therefore, the infrared detector of the present invention has an element for detecting infrared rays, and a metallic case for accommodating the element is provided with a window through which infrared rays pass, and the infrared ray is provided in this window. In an infrared detector provided with an optical filter that transmits light, the optical filter is made of a semiconductor substrate and at least both main surfaces thereof are provided with an optical filter film that transmits infrared light of a desired wavelength. At least a part of the case bonding portion is shaved off to form the thin film shape so that the semiconductor substrate is exposed, and a conductive bonding material is applied to the thin portion of the optical filter to electrically bond the case. gave.

In addition, in an infrared detector having an element for detecting infrared rays, a metal case for accommodating the element is provided with a window for passing infrared rays, and an optical filter for transmitting infrared rays is installed in the window. The optical filter is composed of a semiconductor substrate, at least both main surfaces of which are provided with an optical filter film that transmits infrared rays having a desired wavelength, and a case joint portion of the optical filter is formed by cutting at least a part of the optical filter film, A groove was formed so that the semiconductor substrate was exposed, and a conductive bonding material was applied to the groove of the optical filter to electrically bond it to the case.

Further, the joining portion of the case joined to the thin portion of the optical filter is formed with a thick portion that fits in the thin portion or groove of the optical filter.

[0008]

The case joint portion of the optical filter is formed in a thin shape so as to expose at least a part of the optical filter film (insulating property) so as to expose the semiconductor substrate (conductivity), and the conductive part is formed in the thin portion of the optical filter. By applying the bonding material, only the conductive bonding material is accumulated in the thin portion of the optical filter, and the conductive portion with the semiconductor substrate is formed on the case bonding side main surface of the optical filter. Then, the conductive portion surely electrically bonds the case and the optical filter bonded to the case. Therefore, the electromagnetic shield effect of the case is improved.

In addition, at least a part of the optical filter film (insulating property) is shaved in the case joining portion of the optical filter to form a groove so that the semiconductor substrate (conductive property) is exposed, and in the groove of the optical filter, the conductive property is provided. By applying the bonding material, only the conductive bonding material is accumulated in the groove of the optical filter, and the conductive portion with the semiconductor substrate is formed on the case bonding side main surface of the optical filter. Then, the conductive portion surely electrically bonds the case and the optical filter bonded to the case. Therefore, the electromagnetic shield effect of the case is improved. Further, since the periphery of the conductive portion is protected by the optical filter itself, the conductive bonding material accumulated in the conductive portion is not affected by external influences (bonding material, moisture in air, etc.).

Further, since the thin-walled portion of the optical filter is joined to the thin-walled portion of the case, the thin-walled portion or groove of the optical filter is fitted to the thick-walled portion so that when the optical filter is attached to the case, there is a deviation. The positional accuracy is improved and the bonding strength is improved. And
The thick-walled portion (conductive) of the case contacts the semiconductor substrate of the optical filter, and the conductive bonding material accumulates between the thin-walled portion or groove of the optical filter and the thick-walled portion of the case. A conductive portion with the semiconductor substrate is formed on the surface. Then, the conductive portion surely electrically bonds the case and the optical filter bonded to the case. Therefore, the electromagnetic shield effect of the case is further improved. Further, since the periphery of the conductive portion is protected by the optical filter itself, the conductive bonding material accumulated in the conductive portion is not affected by external influences (bonding material, moisture in air, etc.).

[0011]

Next, a first embodiment of the present invention will be described with reference to the drawings. 1 is a perspective front view showing a first embodiment of the present invention, and FIG. 2 is an enlarged front view of the cap shown in 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 structure. That is, a metal film electrode (Cr or Ni-Cr) for light reception is formed on the surface by means such as vapor deposition at predetermined intervals.
Etc.) 10A, 10B are provided, and metal film electrodes (Ag etc.) 12A, 12B are provided on the back surface. The electrodes 10A and 10B for receiving light are connected electrodes (C
r or Ni-Cr or the like) 11.
The base 1 is made of metal, and an insulating substrate 5 having a printed wiring is installed on the top of the base 1, and FETs 6 constituting an external circuit, electronic components 7 such as resistors, and a support 81 are provided on the front and back surfaces thereof.
A and 81B are mounted, and the pyroelectric element 9 is mounted on the upper portions of the supports 81A and 81B by a conductive bonding material. In addition, the base 1 has a plurality of lead terminals 31 and 32 that are electrically independent of each other, and is hermetically and electrically insulated and sealed in the through hole of the base 1 via glass. The metallic cap 2 for sealing these components is provided with the window 21 on its upper part, and the optical filter 4 for transmitting infrared rays is installed. This optical filter 4 is an optical filter film 4 that transmits only infrared rays in a specific wavelength range to both main surfaces of a semiconductor substrate 41 made of, for example, silicon, germanium or the like.
2 is formed. This is because the sensitivity of the pyroelectric element 9 does not depend on wavelength, and it is necessary to select a desired wavelength region in advance. Electromagnetic noise generated from other electronic components on the circuit board is also absorbed by these optical filters 4, so it is necessary to take measures against these electromagnetic noises. That is, the grooves 41d and 41e as thin portions are formed in the cap joint portion 4a of the optical filter 4.
And a conductive bonding material 13 is provided on the cap bonding portion 4a.
After applying the epoxy resin mixed with a filler (powder) such as silver, copper, or gold, the bonding material 14 (for example, epoxy resin) is applied on top of the conductive bonding material 13 before the conductive bonding material 13 is cured. Then, the two types of bonding materials were cured at once to bond them. Therefore, the grooves 41d, 41 of the optical filter 4 are
Only the conductive bonding material 13 is accumulated in e to form the conductive portion 13a with the semiconductor substrate 41, so that the cap 2 and the optical filter 4 bonded to the cap are reliably electrically bonded. Then, the cap 2 is placed on the base 1 to hermetically seal it.

Next, a second embodiment of the present invention will be described with reference to the drawings. 3 is a front view of a perspective view showing a second embodiment of the present invention, and FIG. 4 is an enlarged front view of the cap of FIG. The same parts as those in the first embodiment are designated by the same reference numerals. 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 structure. That is, on the surface, a metal film electrode (Cr or N) for light reception is formed at a predetermined interval by means such as vapor deposition.
i-Cr, etc.) 10A, 10B, and metal film electrodes (Ag, etc.) 12A, 12B are provided on the back surface. The light-receiving electrodes 10A and 10B are commonly connected by a connecting electrode (Cr or Ni—Cr) 11. Then, the base 1 is made of metal, and the insulating substrate 5 having printed wiring is installed on the upper part, and the FET 6 and the electronic components 7 such as resistors and the supports 81A and 81B forming an external circuit are mounted on the front and back surfaces thereof. Supports 81A, 81B
A pyroelectric element 9 is mounted on the upper part of the by a conductive bonding material. In addition, the base 1 has a plurality of lead terminals 31 and 32 that are electrically independent of each other, and is hermetically and electrically insulated and sealed in the through hole of the base 1 via glass. The metallic cap 2 for sealing these components is provided with the window 21 and the optical filter locking portions 22 and 23 on the upper part thereof, and the optical filter 4 which transmits infrared rays is installed. The optical filter 4 is composed of (for example) an optical filter film 42 that transmits only infrared rays in a specific wavelength range to both main surfaces of a semiconductor substrate 41 made of, for example, silicon, germanium or the like.
Are formed. This is because the sensitivity of the pyroelectric element 9 does not depend on wavelength, and it is necessary to select a desired wavelength region in advance. Electromagnetic noise generated from other electronic components on the circuit board is also absorbed by these optical filters 4, so it is necessary to take measures against these electromagnetic noises. That is, the grooves 41f and 41g as thin portions are provided in the cap joint portion 4b of the optical filter 4, and the conductive joint material 13 (polyimide is mixed with filler (powder) such as silver, copper, or gold) in the cap joint portion 4b. Object) and then the optical filter locking portion 2 of the cap 2
The grooves 41f and 41g of the optical filter 4 are locked and attached to 2 and 23. Then, before the conductive bonding material 13 was hardened, the bonding material 14 (polyimide) was applied to the upper part of the conductive bonding material 13, and the two kinds of bonding materials were hardened at once to bond them. Therefore, only the conductive bonding material 13 is accumulated in the grooves 41f and 41g of the optical filter 4 through the optical filter locking portions 22 and 23 of the cap 2 to form the conductive portion 13b with the semiconductor substrate, and the cap 2 The optical filter 4 bonded to the cap is securely electrically bonded. Then, the cap 2 is placed on the base 1 to hermetically seal it.

The grooves 41d and 41e and the grooves 41f and 41g are illustrated as the thin portions of the optical filters described in the first and second embodiments. 5 and 6 can be considered as plan views of these grooves. However, the thin portion of the optical filter is not limited to the groove, and as shown in FIG. 7, the recessed portions 411a, 411b, 411c, 411 are formed.
A configuration in which d is provided may be used. The number of recesses is not limited to the number shown in the figure, and may be such that a conductive part with the semiconductor substrate is formed as a countermeasure against electromagnetic noise and the case and the optical filter can be reliably electrically joined (at least one or more). Good. Further, as shown in FIG. 8, a configuration in which a groove and a recess are provided may be used.

[0014]

According to the first aspect of the present invention, only the conductive bonding material is accumulated in the thin portion of the optical filter, and the conductive portion with the semiconductor substrate is formed on the case bonding side main surface of the optical filter. Therefore, in the conductive portion, there is no variation in application of the bonding material and the conductive bonding material. In order to simplify the process, there is a method of applying and hardening the bonding material before applying and hardening the conductive bonding material. In the case of using, the joining materials do not disperse in the conducting portion. Then, the conductive portion surely electrically bonds the case and the optical filter bonded to the case.
Moreover, since the thermal expansion coefficients of these bonding materials are close to each other, stress is less likely to be applied to the interface between the bonding materials when the temperature changes. Therefore, it is possible to provide a highly reliable infrared detector in which the electromagnetic shielding effect of the case is improved and which is less affected by the environment and has high manufacturing efficiency.

According to the second aspect of the present invention, only the conductive bonding material is accumulated in the groove of the optical filter, and the conductive portion with the semiconductor substrate is formed on the case bonding side main surface of the optical filter. Therefore, in the conductive portion, there is no variation in application of the bonding material and the conductive bonding material. In order to simplify the process, there is a method of applying and hardening the bonding material before applying and hardening the conductive bonding material. In the case of using, the joining materials do not disperse in the conducting portion. Then, the conductive portion surely electrically bonds the case and the optical filter bonded to the case. Moreover, since the thermal expansion coefficients of these bonding materials are close to each other, stress is less likely to be applied to the interface between the bonding materials when the temperature changes. Therefore, it is possible to provide a highly reliable infrared detector in which the electromagnetic shielding effect of the case is improved and which is less affected by the environment and has high manufacturing efficiency.

According to the third aspect of the present invention, when the optical filter is attached to the case, there is no deviation, the positional accuracy is improved, and the bonding strength is improved. Then, only the conductive bonding material is accumulated in the thin portion or groove of the optical filter through the thick portion of the case, and a conductive portion with the semiconductor substrate is formed on the case bonding side main surface of the optical filter. Therefore, in the conductive portion, there is no variation in application of the bonding material and the conductive bonding material. In order to simplify the process, there is a method of applying and hardening the bonding material before applying and hardening the conductive bonding material. Even if the above is used, the bonding materials do not disperse in the conductive portion. Then, the conductive portion surely electrically bonds the case and the optical filter bonded to the case. Moreover, since the thermal expansion coefficients of these bonding materials are close to each other, stress is less likely to be applied to the interface between the bonding materials when the temperature changes. Therefore, it is possible to provide an infrared detector in which the electromagnetic shielding effect of the case is further improved, which is more reliable, is less affected by the environment, and has higher manufacturing efficiency.

[Brief description of drawings]

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

2 is an enlarged front view of the cap of FIG. 1. FIG.

FIG. 3 is a perspective front view showing a second embodiment of the present invention.

FIG. 4 is an enlarged front view of the cap shown in FIG.

FIG. 5 is a first plan view of the optical filter.

FIG. 6 is a second plan view of the optical filter.

FIG. 7 is a third plan view of the optical filter.

FIG. 8 is a fourth plan view of the optical filter.

FIG. 9 is a perspective front view showing a conventional example.

FIG. 10 is an enlarged front view of the cap of FIG.

[Explanation of symbols]

 1 ... Base 2 ... Cap 31, 32 ... Lead terminal 4 ... Optical filter 5 ... Insulating substrate 6 ... FET 7 ... Resistor 81A, 81B ... Support 9 ... ..Pyroelectric elements 10A, 10B ... Light receiving electrodes 11 ... Connection electrodes 12A, 12B ... Back surface electrodes 13 ... Conductive bonding material 14 ... Bonding materials

Claims (3)

[Claims] 1. An infrared detector comprising an element for detecting infrared rays, wherein a metallic case accommodating the element is provided with a window for transmitting infrared rays, and an optical filter for transmitting infrared rays is installed in the window. The optical filter is made of a semiconductor substrate, at least both main surfaces of which are provided with an optical filter film that transmits infrared rays having a desired wavelength, and a case joint portion of the optical filter is formed by cutting at least a part of the optical filter film. An infrared detector characterized in that the substrate is formed in a thin shape so as to be exposed, and a conductive bonding material is applied to a thin portion of the optical filter to electrically bond with the case. 2. An infrared detecting device, characterized in that a groove is formed as a thin-walled shape to expose the semiconductor substrate, and a conductive bonding material is applied in the groove to electrically bond with the case. vessel. 3. The joint portion of the case joined to the thin portion of the optical filter is a thin portion of the optical filter,
The infrared detector according to claim 1 or 2, characterized in that a thick portion is formed to be fitted therein.