JPH09311076A - Pyroelectric infrared detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pyroelectric infrared detector of superior productivity. SOLUTION: A circuit board 17 is set in a container 1 having an infrared transmission window 4 at an upper part thereof. The circuit board 17 is spaced a predetermined distance from a stem 18 sealing a lower part of the container 1. A pyroelectric infrared thin film element 6 as an infrared detection element which has a pyroelectric thin film 9, an upper electrode 10 and a lower electrode 11 holding the thin film 9 therebetween is arranged on an upper face of the circuit board 17 so that an infrared detection part 12 faces the infrared transmission window 4. A high resistor 24 of a chip type and an FET 25 of a mold type are soldered to the circuit board 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric infrared detector.

[0002]

2. Description of the Related Art Pyroelectric infrared detectors are used in the fields of human body detection, gas analysis, non-contact temperature measurement, etc., but a pyroelectric body as a detection element for detecting infrared rays incorporated in a container. Is PZT, LiTiO ₃ , PVDF
Ceramics, single crystals, and polymer films are used. These pyroelectric materials are used as desired pyroelectric pellets, for example, 4 m based on a block or sheet-shaped base material.
It is processed into a shape of m square × several tens to 100 μm thick, and electrodes are formed to be a predetermined infrared detection element.

The pyroelectric infrared detector requires a high resistance for controlling an electric time constant and an FET for impedance conversion in addition to the infrared detection element. These infrared detection element, high resistance and It is necessary to store the FET inside the container while maintaining hermeticity. Therefore, conventionally, the TO-5 (diameter of about 8 mm) was housed in a metal container having an opening at the bottom, and the opening was sealed with a stem. Note that TO means Transist
It is an abbreviation for or Outline and is used for transistors in the package outline standardized by JEDEC in the United States.

In recent years, in the field of application of the pyroelectric infrared detector, while high-speed response and miniaturization are required, thinning of the pyroelectric body is becoming popular along with establishment of thin film technology. That is, a pyroelectric thin film having a thickness of several μm is formed on a single crystal substrate by a CVD method or a sputtering method as opposed to a conventional method of forming a pyroelectric body by processing a block or sheet-shaped base material. It is a technology. For example, a paper entitled "Development of Micro Pyroelectric Infrared Sensors and Applied Products" (Lighting Society Research Group material: 1996.2.16) has a thickness of 2
MOCVD method (Metal Organic Chemical Vapor Deposition), as introduced in ultra-small element of 100 μm and 100-500 μm square
It has become possible to manufacture a pyroelectric thin film having a thickness of about several μm by such a thin film forming method as described above.

By the way, when a pyroelectric infrared thin film element having an upper electrode and a lower electrode provided on the pyroelectric thin film is used as an infrared detecting element, the container is TO-46 or TO for the purpose of downsizing. Although it may be housed in a shape of about −18, in such a pyroelectric infrared detector, in addition to the infrared detection element, high resistance and FE are also included.
It is necessary to store T in the container.

[0006]

However, the above-mentioned TO-
46 and TO-18 due to restrictions on the arrangement of each element, FE
As T, a small non-molded component called a bare chip must be adopted, and the connection between the lead pin and each component and the mutual connection between components must be performed by wire bonding. There was a problem.

That is, since it is a bare chip part, it is difficult to handle. While the electrodes of the component are exposed on the surface, the stem on which this component is placed is metal, so it is necessary to fix the component with an insulating adhesive. When fixing the above-mentioned components, positioning thereof requires considerable effort. Since wire bonding is used to connect the parts and the lead pins, the production equipment is required. And so on.

The present invention has been made in view of the above matters, and an object thereof is to provide a pyroelectric infrared detector having excellent productivity.

[0009]

In order to achieve the above object, the pyroelectric infrared detector of the present invention comprises a stem having an infrared transmitting window in an upper part, and a stem for sealing the lower part of the container. A circuit board is provided so as to be separated by a predetermined dimension, and a pyroelectric infrared thin film element having a pyroelectric thin film as an infrared detection element and an upper electrode and a lower electrode sandwiching the pyroelectric thin film on the upper surface of the circuit board. Is provided so that its infrared detecting portion faces the infrared transmitting window, and chip type high resistance and mold type FETs are attached to the circuit board by soldering.

In the pyroelectric infrared detector of the present invention, a pyroelectric infrared thin film having a pyroelectric thin film as an infrared detecting element and an upper electrode and a lower electrode sandwiching the pyroelectric thin film are provided on a circuit board. Since the element is provided and the chip type high resistance and the mold type FET are simultaneously attached to the circuit board by soldering, known surface mounting technology such as solder reflow (Surface Mount Technology) is used.
y: SMT), and productivity is improved because it is not necessary to separately perform wire bonding. Since components such as high resistance and FET can be fixed to the circuit board by soldering, the positioning of them is easy due to the effect of self-alignment.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention. First, FIGS. 1A and 1B show an example of a pyroelectric infrared detector of the present invention.
In (A) and (B), 1 is a lower open type tubular container made of metal such as iron, nickel or Kovar,
An opening 3 is formed substantially in the center of the upper surface 2. Reference numeral 4 denotes an infrared transmitting window member provided so as to close the opening 3 from above the container 1, which is not shown in detail,
A wavelength-selective multilayer film is formed on both sides of a base material made of an infrared ray transmissive material such as silicon or germanium, and substantially the entire outer peripheral side surface and the entire peripheral portion of the opening 3 are electrically connected, for example. The material 5 is used to join the container 1 from above the upper surface 2.

Reference numeral 6 is a pyroelectric infrared thin film element as an infrared detecting element provided in the container 1. The structure of the pyroelectric infrared thin film element 6 will be described with reference to FIG. 2. In FIG. 2, 7 is a single crystal substrate made of MgO (magnesium oxide) and has a thickness of about 500 μm. Reference numeral 8 is a minute recess formed on the surface of the substrate 7 by etching. Reference numeral 9 denotes a pyroelectric thin film, which is made of, for example, a PZT-based ferroelectric thin film or a PLZT-based ferroelectric thin film, and has a thickness of about 2 μm. This pyroelectric thin film 9
An upper electrode 10 and a lower electrode 11 made of, for example, Pt (platinum) are provided on both upper and lower surfaces of the so as to correspond to each other. The thickness of these electrodes 10 and 11 is 0.2, for example.
It is about μm. The portion where the electrodes 10 and 11 and the pyroelectric thin film 9 overlap with each other when viewed in the direction of arrow A is referred to as an infrared detection unit 12.

Reference numeral 13 denotes an infrared absorbing film provided so as to cover the upper surface of the upper electrode 10 as a light receiving electrode in the infrared detecting section 12, and a photosensitive organic thin film capable of photolithography is provided with an infrared absorbing material such as carbon black. It is appropriately mixed. Reference numeral 14 denotes an insulating thin film formed around the infrared detecting unit 12 for holding the infrared detecting unit 12 with respect to the substrate 7. The insulating thin film is an organic insulating thin film such as a polyimide resin thin film or an inorganic insulating film such as a SiO ₂ thin film. It consists of a thin film. 15 and 16 are the upper electrode 10 and the lower electrode 1
One is an upper extraction electrode and the other is a lower extraction electrode.

As can be understood from the above description, the pyroelectric infrared thin film element 6 used in the present invention is extremely thin.
The thickness is less than or equal to mm, and the size is at most about 1 mm square. It should be noted that the detailed structure of the pyroelectric infrared thin film element 6 having such a structure and the manufacturing method thereof are separately applied for a patent.

Referring back to FIGS. 1A and 1B again, the pyroelectric infrared thin film element 6 is provided on the circuit board 17 made of ceramic or the like so that the infrared detecting portion 12 thereof faces the infrared transmitting window material 4. Has been. This circuit board 17
It is provided so as to be separated from the upper surface of the stem 18 for sealing the lower part of the container 1 by a predetermined dimension. That is, 19 and 20 are lead pins extending outside the case 1 through a through hole 21 provided in the stem 18, and are arranged concentrically so as to divide the circumference into four equal parts, for example, as shown in FIG.
As shown in (B), the two lead pins 19 are arranged in the XX direction, and the other two lead pins 20 are arranged in the YY direction orthogonal to the XX direction. These lead pins 1
9 and 20 are elongated cylindrical shapes having the same diameter as each other, and the lead pin 19 is formed slightly longer than the lead pin 20.

The upper end 19a of one lead pin 19 is inserted into each of the two through holes formed in the circuit board 17 so that the upper end 19a does not project from the upper surface of the circuit board 17. It is fixed by a conductive bonding material 22 such as solder for bonding with the circuit pattern of the board 17. As a result, the position of the circuit board 17 in the X and Y directions is fixed.

The upper end surface of the other lead pin 20 is brought into contact with the lower surface of the circuit board 17, and is fixed by an appropriate adhesive 23. As a result, the circuit board 17 is fixed in position in the Z direction shown in FIG. The adhesive 23 may be the same material as the conductive bonding material 22.

Reference numeral 24 is a chip type high resistance provided on the upper surface side of the circuit board 17 for setting the time constant of the output circuit, and 25 is a mold type for impedance conversion provided on the lower surface side of the circuit board 17. FET. The high resistance 24 and the FET 25 are attached to the circuit board 17 by a surface mounting technique such as a solder reflow technique.

As described above, in the pyroelectric infrared detector according to the present invention, the circuit board 17 is provided in the container 1 at the upper ends of the plurality of lead pins 19 and 20 which are inserted into the container 1 from the outside. On this circuit board 17, a pyroelectric infrared thin film element 6 having a pyroelectric thin film 9 and an upper electrode 10 and a lower electrode 11 provided so as to sandwich the pyroelectric thin film 9 is provided as an infrared detecting element, and at the same time, Since the chip type high resistance 24 is mounted on the upper surface and the mold type FET 25 is mounted on the lower surface by soldering, respectively, it can be produced by using a known surface mounting technique such as solder reflow, and wire bonding is frequently used. Productivity is improved because there is no need.

As described above, the high resistance 24 and the FE
Since components such as T25 can be fixed to the circuit board 17 by soldering, their positioning is easy due to the effect of self-alignment.

In the pyroelectric infrared detector of the present invention, the infrared detecting element is composed of the pyroelectric infrared thin film element 6, is extremely thin and compact, and has a high resistance 24.
Since the FET 25 and the FET 25 are small and easy to handle, and can be mounted compactly on the circuit board 17,
The entire pyroelectric infrared detector can be made compact.

The attachment of the components such as the high resistance 24 and the FET 25 to the circuit board 17 is not limited to the above-described embodiment, and the high resistance 24 and the FET 25 are provided on the lower surface of the circuit board 17, for example. It suffices that the solder be attached using solder.

[0024]

As described above, according to the present invention, a pyroelectric infrared detector having excellent performance such as high-speed response can be mass-produced at low cost.

[Brief description of drawings]

FIG. 1 shows an example of a pyroelectric infrared detector of the present invention,
(A) is a longitudinal sectional view, (B) is a plan view.

FIG. 2 is a vertical view showing an example of a pyroelectric infrared thin film element incorporated in the pyroelectric infrared detector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Container, 4 ... Infrared transmitting window, 6 ... Pyroelectric infrared thin film element, 9 ... Pyroelectric thin film, 10 ... Upper electrode, 11 ... Upper electrode, 12 ... Infrared detector, 17 ... Circuit board, 18 ... Stem , 24 ... High resistance, 25 ... FET.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Matsumoto 2 Higashimachi, Kichijoin Miya, Minami-ku, Kyoto-shi, Kyoto

Claims (3)

[Claims] 1. A container provided with an infrared transmitting window at the top,
A circuit board is provided apart from the stem for sealing the lower part of the container by a predetermined dimension, and a pyroelectric thin film and an upper electrode and a lower electrode provided so as to sandwich the pyroelectric thin film are provided on the upper surface of the circuit board. The pyroelectric infrared thin film element is provided so that its infrared detecting portion faces the infrared transmitting window, and a chip type high resistance and a mold type FET are attached to the circuit board by soldering. Infrared detector. 2. A high resistance is provided on the upper surface of the circuit board, and FE is provided on the lower surface.
The pyroelectric infrared detector according to claim 1, wherein T is arranged. 3. The inner diameter of the container is 5 mm or less.
Alternatively, the pyroelectric infrared detector described in 2.