JPH063184A - Infrared detector of pyroelectric type - Google Patents

Abstract

PURPOSE:To provide the title device the insulation resistance of which is sufficiently secured. CONSTITUTION:The title device is provided with a substrate 14, on which a conductive pattern is formed, within a case 7, FETs 3, 4 connected to the conductive pattern and gate bias resistors 5, 6 thereof, on the substrate, and also pyroelectric elements 1, 2, above the substrate 14. Through holes 30, 31 are formed between the conductive pattern between the FETs 3, 4 and the resistors 5, 6, and the conductive pattern of earth side.

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 for human body detection sensors and sensors for automatic lighting devices. Pyroelectric infrared detectors are used in a metal case with a window.
A substrate on which a conductive pattern is formed is provided, an FET connected to the conductive pattern and its gate bias resistor are provided on the substrate surface, and a pyroelectric element is provided above the substrate so as to face the window. .

As the gate bias resistor incorporated in the pyroelectric infrared detector, a thick film resistor manufactured by applying a resistance paste on a ceramic substrate and firing the paste is used. This gate bias resistance is usually 10 ¹¹ Ω (10
It has a very high resistance value of 0 GΩ) or more,
In order to maintain the stability and insulation of the resistance value, protect the resistor part by coating it with glass, etc., and change the temperature and humidity, and the resistance value due to surface adsorbed substances by setting a sufficient insulation distance. To prevent fluctuations and deterioration.

[0004]

By the way, recently, in the pyroelectric infrared detector, there is a tendency to combine the pyroelectric elements into multiple elements (integration), but on the substrate of the resistor portion. Occupies an increased area, which has become one of the major obstacles in realizing this multi-element structure.
Therefore, it is conceivable to use a chip resistor instead of the thick film resistor. According to this, although the size of the resistor itself is considerably reduced, it is necessary to sufficiently insulate it from the conductive pattern formed on the substrate, which is an obstacle to increasing the degree of integration on the substrate. Was there.

The present invention has been made in consideration of the above matters, and an object of the present invention is to provide a pyroelectric infrared detector in which sufficient insulation is ensured, which is a problem in integration. To do.

[0006]

To achieve the above object, in the present invention, a substrate on which a conductive pattern is formed is provided in a case, and an FET and its gate bias connected to the conductive pattern are provided on the substrate surface. In a pyroelectric infrared detector having a resistor and a pyroelectric element above a substrate, a through hole is formed between a conductive pattern between the FET and the gate bias resistor and a conductive pattern on the ground side. is doing.

[0007]

In the pyroelectric infrared detector having the above structure, the through hole formed in the substrate allows the creepage distance between the conductive pattern between the FET and the gate bias resistor and the conductive pattern on the ground side to be reduced. growing. Therefore, even if, for example, a chip resistor is used as the gate bias, the insulation between the gate of the FET and the conductive pattern on the ground side of the substrate can be sufficiently maintained.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an example of a pyroelectric infrared detector according to the present invention. The pyroelectric infrared detector in this embodiment is of a dual twin type, as can be understood from the internal circuit shown in FIG. That is, in FIG. 3, 1 and 2 are pyroelectric elements, 3 and 4 are, for example, J-FETs (junction type field effect transistors) corresponding to the pyroelectric elements 1 and 2, 5 and 6 are J-FETs 3, 3.
4 are gate bias resistors corresponding to 4 respectively. V _D
Is a power input terminal, S ₁ and S ₂ are signal output terminals, and E is a ground terminal.

Next, FIG. 1 shows the structure of the pyroelectric infrared detector. In this figure, 7 is a metal case, and the center of the upper surface of the case is made of an infrared transparent material, for example, a rectangular shape. Transparent window 8 is formed. Reference numeral 9 denotes a metal stem that closes the lower opening of the case 1, and four lead pins 10 to 13 are held therethrough. These lead pins 10, 11, 12, and 13 form the power input terminal V _D , the signal output terminals S ₁ and S ₂ , and the ground terminal E, respectively.

Reference numeral 14 denotes a glass epoxy resin substrate, for example, its size is 0.5 mm in thickness and 10 mm.
There are four sides. The board 14 is held on the upper ends of the lead pins 10 to 13. Then, connection points 15 to 18 made of conductive through holes are formed at four corners of the substrate 14, and the lead pins 10 to 13 are respectively inserted into these connection points 15 to 18 to provide an appropriate seal. The lead pins 10-13 and the connection points 15-18
And are electrically connected to each other.

As shown in FIG. 2, the J-FETs 3 and 4 and the gate bias resistors 5 and 6 are provided on the upper surface of the substrate 14, and the respective parts of the J-FETs 3 and 4 and the gate biases are provided. A plurality of conductive patterns 19 to 26 for appropriately connecting the resistors 5 and 6 and the connection points 15 to 18 to each other.
Is formed, and further, connection points 27 and 28 formed of conductive through holes are formed.

That is, the drain 3D of one J-FET 3 is connected to the connection point 15 via the conductive pattern 19, the source 3S thereof is connected to the connection point 16 via the conductive pattern 20, and further the gate thereof. 3G is connected to one end of the gate bias resistor 5 via the conductive pattern 21. The other end of the gate bias resistor 5 is connected to the connection point 18 via the conductive pattern 22.

The drain 4D of the other J-FET 4 is connected to a connection point 27 via a conductive pattern 23, and this connection point 27 is connected via a conductive pattern (not shown) provided on the back surface of the substrate 14. It is connected to point 15. The source 4S of the J-FET 4 is connected to the connection point 17 via the conductive pattern 24, and its gate 4G is provided.
Is connected to one end of the gate bias resistor 6 via the conductive pattern 25. The other end of the gate bias resistor 6 is connected to a connection point 28 via a conductive pattern 26, and the connection point 28 is connected via a conductive pattern (not shown) provided on the back surface of the substrate 14. It is connected to 18.

29 is, for example, PZT (titanium zircon
Ferroelectric material such as lead-based oxide ceramics),
By subjecting this to polarization processing, four light receiving parts a,
b and cd are formed, and the pyroelectric elements 1 and 2 are formed by appropriately connecting them, and one terminal of the pyroelectric element 1 is connected to the conductive patterns 21 and 22. Both terminals of the other pyroelectric element 2 are connected to the conductive patterns 25 and 26.

In this embodiment, through holes 30 and 31 are formed in the substrate 14. More specifically, a width of 0.3 mm and a length of 2.5 mm are provided between the conductive patterns 21 and 25 between the J-FETs 3 and 4 and the gate bias resistors 5 and 6 and the conductive patterns 22 and 26 on the ground side.
Through holes 30 and 31 are formed. As a means for providing such through holes 30 and 31 in the substrate 14, a die-cutting mask member is used to form a through hole 10
Processing by so-called sandblasting in which fine particles of a certain degree are sprayed is, for example, chemical etching processing using a strong acid such as HCl.

In this embodiment, the gate bias resistors 5 and 6 are provided so as to straddle the through holes 30 and 31, respectively.

In the pyroelectric infrared detector constructed as described above, the through holes 30, 31 formed in the substrate 14 are formed.
Therefore, the J-FETs 3, 4 and the gate bias resistor 5,
The creeping distance between the conductive patterns 21 and 25 between 6 and 6 and the conductive patterns 22 and 26 on the ground side increases. J
-The insulating properties between the gates 3G and 4G of the FETs 3 and 4 and the conductive patterns 22 and 26 on the ground side of the substrate 14 can be sufficiently maintained.

The present invention is not limited to the above embodiment, but alumina ceramics or silicon wafers can be used as the material of the substrate 14, for example. When the substrate 14 is made of alumina ceramic, the through holes 30, 31
It is preferable that the above-mentioned processing is performed by the above-mentioned means. When the substrate 14 is formed of a silicon wafer, the through holes 30,
For the processing of 31, any of the above-mentioned means may be used.

A FET other than the J-FET may be used. Further, the pyroelectric infrared detector may be one other than the above dual twin type, and the present invention exerts a great effect particularly in a multi-element of four elements, eight elements or more.

[0020]

As described above, according to the present invention,
Since the insulation between the conductive pattern between the FET and the gate bias resistor and the conductive pattern on the ground side is sufficiently maintained, sufficient insulation can be obtained even if other conductive patterns are brought close to each other, and as a result, the integration of components can be achieved. Can be promoted to a higher degree. In addition, since the insulation is further increased by the through holes formed in the substrate, it is possible to prevent the insulation deterioration due to surface ionic conduction caused by the adsorption of moisture or gas on the substrate surface. The reliability of the pyroelectric infrared detector against environmental changes is improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a pyroelectric infrared detector according to an embodiment of the present invention.

FIG. 2 is a diagram showing a planar configuration of a substrate in the pyroelectric infrared detector.

FIG. 3 is a diagram showing a configuration example of an internal circuit of the pyroelectric infrared detector.

[Explanation of symbols]

1, 2 ... Pyroelectric element, 3, 4 ... FET, 5, 6 ... Gate bias resistance, 7 ... Case, 14 ... Substrate, 19-26 ... Conductive pattern, 30, 31 ... Through hole.

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

Claims (1)

[Claims] 1. A substrate on which a conductive pattern is formed is provided in a case, and an FET connected to the conductive pattern and its gate bias resistor are provided on the surface of the substrate.
In a pyroelectric infrared detector having a pyroelectric element above a substrate, a through hole is formed between a conductive pattern between the FET and the gate bias resistor and a conductive pattern on the ground side. Pyroelectric infrared detector.