JPS6015008B2 - thermal infrared detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal infrared detector, and more particularly to a thermal infrared detector using, for example, a pyroelectric effect type infrared detecting element and provided with a novel package.

2. Description of the Related Art As thermal infrared detectors, for example, those using torpedo-shaped detection elements or thermistors are known. An infrared detector using a dew-type detection element, which is the background of this invention, is shown in FIG. As shown in FIG. 1, a conventional infrared detector has a pyroelectric effect element, that is, an infrared detection element 3, fixed to an insulating substrate 2 through which external lead-out pins 1 and 1' are fixed, and the substrate 2 is fixed in a space. 4 to the hermetic base 5. Then, a metal case 6 having a hole 6a for receiving infrared rays is hermetically sealed to the hermetic base 5 so as to surround the substrate 2. A window member 7 made of a material capable of transmitting infrared rays in a desired wavelength range is provided in the hole 6a of the metal case 6. As is generally known, packages using a hermetic seal structure have a metal case, which provides an electrical shielding effect, and is also structurally strong. When applied to containers, the following drawbacks arise that must be resolved.

That is, {1) Since the package cost is high, it can only be applied to expensive special uses. (2) It is difficult to construct a so-called vertical structure in which external leads are drawn out parallel to the substrate. {3} It is difficult to use flexible covered lead wires as external leads. [41] Since the case is made of metal, when a window member made of a material such as polyethylene is attached to the case with adhesive, the adhesive may seep into the infrared transmitting area, causing sensitivity fluctuations.
It also has poor workability. '5} Since the metal case has a large heat capacity, when the ambient temperature around the detector suddenly changes from low to high, fog will form around the case and the fog will be transmitted to the window parts, blocking infrared rays and causing damage to the window parts. Moisture may enter the case through the parts that are attached to the case. ■When storing a field-effect transistor (hereinafter referred to as "FET") that is connected after the detection element in a case, the moisture resistance of the FET itself is still insufficient, so it is necessary to prevent the influence of moisture from entering the case. For example, it is necessary to coat this FET with a resin.

The '71 metal case has good thermal conductivity, and the board on which the detection element is mounted is usually an alumina board with good thermal conductivity, so if the case and the board come into contact during assembly, infrared rays with gradual energy changes can be detected. It is difficult to do so.
Furthermore, since the shelf uses a metal case, it is inevitably large, making it difficult to downsize it. Therefore, in this invention,
A thermal infrared detector with a new package structure that can overcome all the above-mentioned drawbacks is provided.

In summary, the present invention is such that a thermal infrared detection element is attached to one main surface of a solid or hollow cylindrical support to which an external lead is attached, and the support is protruded toward the other main surface. A heat-shrinkable tube with a length longer than A resin layer, such as paraffin resin, is formed on the inwardly contracted portion.

The above objects and other objects and features of the invention will become more apparent from the following detailed description with reference to the drawings.

In addition, in the following examples, as a thermal infrared detection element,
For example LITa03, PbTj03, SBN, PZT
I will explain the pyroelectric element which is processed into small pieces.
The invention further provides, for example, Ni, Co, Mn, Cu,
It should be noted in advance that it can also be applied to composite oxides such as Fe in the form of flakes, or composite oxides formed as thick or thin films on substrates, that is, those using thermal infrared detection elements such as thermistor bolometers. Let me point this out.

FIG. 2 is a structural sectional view showing an embodiment of the present invention.
In construction, this example uses a cylindrical support 10 having a hollow section 12. The cylindrical support 10 is made of an insulator such as alumina ceramic. The hollow portion 12 of the cylindrical support 10 is formed to obstruct the heat sink of the pyroelectric infrared detection element 20 attached to one main surface of the cylindrical support 10. For example, the hollow portion 12 is formed between the element 20 and the support 10. If you insert a heat insulating substrate etc.
This support 10 may be solid. In this specification, both solid and hollow supports are expressed as the cylindrical support 10. The infrared detection element 20 is, for example, a third
It is configured as shown in the figure.

That is, in the element 20, electrodes 22 and 23 are provided on both sides of a ceramic substrate 21 such as PbTi03, and after polarization treatment is performed between the electrodes 22 and 23 to give an exposure effect, one electrode is A blackened film 24 is formed on the surface of 23. This blackened film 24 becomes a light-receiving surface for effectively receiving infrared rays. Therefore, this element 20 is mounted on the cylindrical support 1 such that the light-receiving surface, that is, the blackened film 24 faces outward.
Adhesive or attached to the - side main surface of 0. External lead-out leads 11, 11' are provided on the other main surface side of the cylindrical support 10.
is fixed.

Further, on the other main surface side of the support body 10, an FET 30 connected to the rear stage of the element 20 is provided in the hollow portion. The FET 30 is fixed to the other main surface of the support 10 by FET leads 31 and 32. Furthermore, a film resistor 40 is formed on the other main surface, which serves as an operating resistance (Rg, Rs) of the FET 30. These elements 20, FET 30, film resistor 40, and external leads 11, 11' are connected, for example, as shown in FIG. 4. Further, a heat-shrinkable tube 60 is placed over the circumferential side of the cylindrical support 10 .

The length of this heat-shrinkable tube 60 is selected to be longer than the length of the cylindrical support 10, and its long portion 61 protrudes toward one main surface side of the support 10, that is, the side on which the element 20 is attached. It is covered like this. When the heat-shrinkable tube 60 is shrunk by heating, the long portion 61 is shrunk so that its green end faces inward, as shown in FIG. The space defined by the long portion 61 of the heat-shrinkable tube 60 and the other main surface of the cylindrical support 10 are filled with a paraffin resin such as polyethylene, polypropylene, etc.
Resin layers 71 and 72 that transmit predetermined infrared rays are formed.

When forming the resin layers 71 and 72, this resin may also flow into the hollow portion 12 of the cylindrical support. After curing, the paraffin-based resin layer 71 formed in this manner is held down by the long portion 61 of the heat-shrinkable tube 60, so that it becomes a mechanically strong environmentally resistant coating material and also prevents infrared rays from transmitting to the element 20. It also serves as a window. For example, if polyethylene is used as the material for this resin layer 71, this polyethylene has superior water vapor impermeability compared to other resins, and therefore, water vapor impermeability is the most important environmental resistance characteristic. This is particularly good in the case of a detector using a dew-type detection element. According to an experiment, when the detector was left in a high-temperature atmosphere for about 10 hours and then taken out and tested, for example, in the conventional infrared detector shown in Figure 1, the gap between the metal case and the window member was Because water vapor enters the product, it only returns to its state before being left in the humidity about 7 hours after it is removed from this humid environment. This is because water vapor is trapped inside the metal case and it takes time for this water vapor to be released to the outside again. On the other hand, according to this embodiment, no matter what kind of humidity it is left in, it returns to its state before being left in the greenery within about one hour. It can be seen from such test data that the environmental resistance properties of this example are good. FIG. 5 is an illustrative diagram showing an example of using such an infrared detector.
Since the infrared detector 100 normally has a small amount of change in output as it is, it is necessary to amplify the amount of change in output by an electric circuit like the FET 30 shown in FIG. 4 or optically. Optical amplification means include a method using an infrared transmitting lens and a method using a concave mirror as shown in FIG. Lenses are very expensive, so in most cases a condenser mirror is used. As shown in FIG. 5, the condensing mirror 200
When using, the incident infrared radiation is 30 degrees, and this mirror is 200 degrees.
The reflected infrared light 300a enters the light-receiving surface of the detector 100 provided at a certain point. However, when such a condensing mirror 200 is used, the portion of the total incident infrared rays that is blocked by the detector 10 does not reach the mirror 200 and therefore does not enter the light receiving surface of the detector 100. become. Therefore, as long as a method using such a condensing mirror 200 is explored, the detector 10
It is necessary to suppress the decrease in the amount of incident light due to "obstruction" of zero. For this reason, it is desired that the detector 100 itself be made as small as possible. Therefore, in the case of the embodiment shown in FIG. 2, it can be made much smaller than the conventional one using a metal case, and therefore the decrease in the amount of light incident on the light receiving surface of this detector 100 can be minimized. It can be stopped. Note that when such an infrared detector 100 is actually used, the electrical shielding effect is poorer than that of a conventional metal case package. By housing a circuit such as an amplifier (not shown) and the detector 100 in the same shield case, electrostatic induction can be avoided and stable operation can be achieved.

Next, an embodiment of a method for manufacturing such an infrared detector will be described with reference to FIG. 2, FIG. 6, and FIG. 7.

First, a cylindrical support 10 made of, for example, alumina ceramic is prepared.

Then, if necessary, for example, a resistor Rg shown in FIG.
Then, the film resistor 40 corresponding to Rs and the electrodes associated therewith are formed by a method such as printing or bonding. after that,
A tortoise-shaped infrared detection element 2 is mounted on one main surface of the support 10.
0 with an adhesive such as epoxy resin. At the same time, the FET 30 is attached to the other main surface side of the support body 10 and located in the hollow portion 12 using FET leads 31 and 32. The external leads 11, 11' of this support 10' are connected to the lead wires 3.
(FIG. 6) is attached, and wires are connected using the connecting portions 51, 51' and 52 so as to have a circuit configuration as shown in FIG. 4, for example. Thereafter, as shown in FIG. 7, a heat-shrinkable tube such as ST-40D having a portion 61 longer than the length of the support 10 is attached to the circumferential side of the support 10.
Cover with G (product name: Shin-Etsu Silicon). At this time,
The long portion 61 is always placed over one main surface of the support 10 so as to protrude therefrom. Thereafter, it is heated, for example, at about 150°C. Accordingly, the long section 6 of the heat-shrinkable tube 60
1 has its edges contracted and contracted inward as shown in FIG. At this time, as the material of the heat-shrinkable tube 60, when the resin layers 71 and 72 are made of paraffin resin, it is desirable to use the same type of paraffin resin. By doing so, the resin layer 71 and the tubes 60, 6
The adhesion with 1 becomes better. Subsequently, after being heat-shrinked as described above, it is immersed in a liquid of melted paraffin wax at about 110 qo. Then, it is taken out from the liquid and cured at room temperature. In this way, an infrared detector 100 having a structure as shown in FIG. 2 is obtained. In the above-mentioned embodiment, an example was explained in which the heat-shrinkable tube 60 was shrunk and then dipped in a paraffin wax liquid, but the following method is also conceivable. That is, as shown in FIG. 7, a heat-shrinkable tube is placed over the cylindrical side of the support 10, and then dipped in a molten polyethylene solution at about 150 to 180 qo. then,
Since the temperature is high, the heat-shrinkable tube 60 contracts and resin layers 71 and 72 as shown in FIG. 2 are formed. In addition, in this case as well, as in the previous example,
It is desirable that the materials of the heat-shrinkable tube 60 and the resin layers 71 and 72 contain the same components. As a result, the tube and the resin layer will be welded to each other, and an infrared detector that is even stronger and has excellent moisture resistance will be obtained. As described above, according to the present invention, since the detector is coated with a heat-shrinkable tube and paraffin resin, it is more efficient and economical than the conventional one using a metal case. Capable of mass production.

Further, the detector structure can have any configuration such as horizontal, vertical, or structure using flexible covered lead wires, increasing flexibility in design. Furthermore, since there is no need to glue the window material as in the past, there is no need for adhesive to adhere to the light-receiving part of the detection element, and it can be manufactured without worrying about adhesion, eliminating variations in performance and increasing workability. . This detector is coated with resin, so
Even if the ambient temperature suddenly changes, fog is hardly generated and the light receiving part of the element is not affected. moreover,
As shown in FIG. 2, if the resin layer 72 is also formed on the other main surface side of the cylindrical support 10, the built-in FET etc. will be wrapped in a resin exterior, and this FET
There is no need for special treatment to improve moisture resistance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustrative structural diagram showing a conventional infrared detector which is the background of the present invention.

FIG. 2 is a structural diagram showing an embodiment of the present invention.
FIG. 3 is an illustrative diagram showing the structure of the aggressive type infrared detection element 20. FIG. 4 shows an equivalent circuit of the embodiment shown in FIG. FIG. 5 is an illustrative diagram showing an example of optically amplifying the amount of change when the infrared detector 100 is actually used. 6 and 7 are structural diagrams showing the manufacturing process of the embodiment shown in FIG. 2. FIG. In the figure, 100 is an infrared detector, 10 is a cylindrical support, 20' is a dew-type infrared detection element, 30 is an FET, 40 is a film resistor, 6 is a heat-shrinkable tube, and 61 is a long tube 60. Portions 71 and 72 indicate resin layers. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1 Made of an insulator and formed into a solid or hollow cylinder,
a support body with an external lead-out lead attached to a predetermined position;
A thermal infrared detection element attached to one main surface of the cylindrical support, and a heat-shrinkable tube to be placed over the side surface of the support, the length of which is selected to be longer than the length of the support. and this long portion protrudes toward said one major surface and is contracted inwardly when said tube is placed over the side surface of the support, and at least said inner side of said heat-shrinkable tube. formed in a space defined by the long portion contracted to
A thermal infrared detector comprising a resin layer made of a resin material that transmits predetermined infrared rays.