JPH0783755A - Infrared detector - Google Patents

Abstract

PURPOSE:To improve the cooling efficiency of an infrared detecting element and, at the same time, to reduce the size and cost of the infrared detector., CONSTITUTION:In the infrared detector in which electronic cooling elements 21 provided in contact with the internal surface of a sealed case and infrared detecting element 24 which is cooled by means of the elements 21 are housed in the sealed case, the element 24 is directly put on the bottom of the recessed thin section 23 of a wiring board 22 having the thin section 23 and a wiring pattern for connecting the element 24 to an external circuit and the electronic cooling elements 21 are stuck to the rear surface of the wiring board 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically cooled infrared detector. Generally, an infrared detection element (photoelectric conversion element for infrared detection) made of a binary or ternary compound semiconductor is
Used in the cooled state to obtain the desired sensitivity characteristics. As a cooling means, a Joule-Thomson cooler or the like is known, but an electronic cooling element using the Peltier effect or the like is excellent in outdoor use because it does not require replenishment of the refrigerant, and is relatively It is attracting attention because it is cheap.

Since these electronic cooling element and infrared detecting element are housed in a hermetically sealed case, a wiring structure for electrically connecting a circuit outside the case and the infrared detecting element is required. However, this wiring structure does not hinder the cooling of the infrared detection element and needs to be provided at a low cost.

[0003]

2. Description of the Related Art FIG. 7 is a sectional view showing a conventional technique. In the figure, 1 is a sealed case, and the sealed case 1 is
It is composed of a lower case (base part) 2, a middle case 3 and an upper lid 4. A wiring board 5 is integrally attached to the middle case 3 so as to penetrate the wall thereof. The wiring board 5 is made of, for example, ceramics, and a wiring pattern is formed on the surface thereof. The upper lid 4 is integrally provided with an infrared transmitting window 6 near the center thereof. The lower case 2, the middle case 3 and the upper lid 4 are joined to each other by a joint 7
Are assembled by welding.

An electronic cooling element 8 utilizing the Peltier effect is provided substantially at the center of the bottom surface of the lower case 2 (two stages are shown in the figure, but one stage or more stages are also available. ) Is provided, a wiring substrate 9 made of sapphire or the like having a wiring pattern formed thereon is adhered to the electronic cooling element 8, and an infrared detection element 10 is further adhered. The infrared detection element 10 is generally mounted on the electronic cooling element 8 after having been evaluated for characteristics and the like while being fixed integrally on the wiring board 9.

The infrared detection element 10 and the wiring pattern on the wiring board 9 are bonded and connected by a wire such as gold, and the wiring pattern of the wiring board 9 and the wiring pattern of the wiring board 5 are similarly bonded and connected by the wire 11. As a result, the infrared detection element 10 and the circuit outside the case are connected.

[0006]

However, according to the prior art, since the infrared detecting element 10 is mounted on the electronic cooling element 8 via the wiring board 9, heat generated according to the thickness of the wiring board 10 is eliminated. There is a problem that the infrared detection element 10 does not reach the required cooling temperature due to the resistance. Here, in order to reach the required cooling temperature, the cooling capacity of the electronic cooling element may be improved, but this measure causes the infrared detector to become large due to the large electronic cooling element, and the cost increases. There is a problem of inviting.

Further, the conventional hermetically sealed case 1 has a large number of constituent parts and a large number of welded parts, so that there is a problem in cost and airtightness as a whole from the viewpoint of the cost of each part and the number of assembling steps, and it is also miniaturized. There is a problem that there is a problem.

The present invention has been made in view of the above points, and it is an object of the present invention to improve the cooling efficiency of an infrared detecting element and to reduce the size and cost of an infrared detector. is there.

[0009]

[Means for Solving the Problems]

(1) First configuration of the present invention In an infrared detector containing an electronic cooling element provided in contact with an inner wall of the case and an infrared detection element cooled by the electronic cooling element in the sealed case, The detection element is provided in contact with the bottom surface of the thin portion of the wiring board having a concave thin portion on the front surface side and having a pattern for connecting the infrared detection element to a circuit outside the case, and the back surface of the wiring board. The side is bonded to the electronic cooling element. (2) Second configuration of the present invention An infrared detector comprising an electronic cooling element provided in contact with an inner wall of the case and an infrared detecting element cooled by the electronic cooling element in a sealed case, wherein the infrared rays are A sensing element is directly bonded onto the electronic cooling element, and a wiring pattern for connecting the infrared sensing element to a circuit outside the case is provided on the surface of the electronic cooling element to which the infrared sensing element is bonded. . (3) Third configuration of the present invention A case, which is composed of a lower case having an opening on the upper surface thereof and an upper lid having an infrared transmitting window for sealing the opening of the lower case, and is provided in contact with the bottom surface of the lower case. An electronic cooling element, an infrared detecting element provided on the electronic cooling element, a plurality of lead pins penetrating the wall of the lower case, and a plurality of integrally provided on the inner wall of the lower case. And a wiring board having a pattern for connecting the infrared detection element and the lead pin while being supported in the vicinity of the infrared detection element by the first projection and the lead pin.

In this structure, a plurality of getter support pins provided through the wall of the lower case and a getter supported by the getter support pins are provided, and the wiring board is also supported by the getter support pins. Can be configured as.

Further, a plurality of second protrusions provided on the upper lid of the case corresponding to the first protrusions of the lower case are provided,
The wiring board may be configured to be fixed by being sandwiched by the first protrusion and the second protrusion.

[0012]

[Action]

(1) According to the first configuration of the present invention, the infrared detecting element is
It is provided in contact with the bottom surface of the thin portion of a wiring board having a concave thin portion on the front surface side and having a wiring pattern for connecting the infrared detection element to a circuit outside the case, and the back surface of the wiring board. Since it is joined to the electronic cooling element, the thickness of the wiring substrate existing between the infrared detection element and the electronic cooling element can be made thinner than before, so that the reduction of the cooling capacity due to the thermal resistance of this portion is reduced. be able to. (2) According to the second aspect of the present invention, the infrared sensing element is directly bonded onto the electronic cooling element, and the infrared sensing element is provided on the surface of the electronic cooling element where the infrared sensing element is bonded. Since the wiring pattern for connecting to the external circuit is provided, the thermal resistance between the infrared detection element and the electronic cooling element is almost eliminated, and the decrease in cooling capacity can be further reduced. (3) According to the third configuration of the present invention, the substrate is supported by the protrusions on the inner wall of the lower case and the lead pins, and the infrared detection element and the circuit outside the case are connected by the lead pins and the wiring pattern of the wiring substrate. Done through. Since the number of constituent parts of the case is smaller than that of the conventional case and the number of joints is also smaller, it is possible to reduce costs, reduce the number of assembling steps, improve airtightness, and reduce the size.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. (1) First Embodiment of the Present Invention FIG. 1 is a cross-sectional view showing the configuration of the main part of a first embodiment of the present invention. In the figure, reference numeral 21 is an electronic cooling element utilizing the Peltier effect, and this electronic cooling element 21 is provided so as to come into contact with the inner wall of the lower case of a sealed case (not shown).

Reference numeral 22 is a wiring substrate made of sapphire or borosilicate glass. The wiring substrate 22 has a substantially trapezoidal concavity (thin portion) 23 near the center on the front surface side, and a wiring pattern is formed on the surface thereof. Are formed.

Reference numeral 24 denotes an infrared detection element (photoelectric conversion element for infrared detection). The infrared detection element 24 is formed in a substantially trapezoidal shape and is wired so that opposing surfaces (especially bottom surface) are joined. It is fitted in the recess 23 of the substrate 22 and fixed to the wiring substrate 22 with an adhesive or the like.

The infrared detection element 24 and the wiring pattern on the wiring board 22 are bonded and connected by a wire 25 such as gold. The infrared detection element 24 mounted on the wiring board 22 is, in this state, evaluated for characteristics and the like, and then is fixedly bonded to a predetermined position of the electronic cooling element 21 as shown in FIG. However, they are closed by an upper lid having an infrared transmitting window at a predetermined position while accommodating them. Wire 2 between the infrared detector and the circuit outside the case
5, connection is made via the wiring pattern on the wiring board 22 and other means.

According to this embodiment, the concave portion 2 is formed in the wiring board 22.
3 is formed so that the infrared detecting element 24 is fitted into the concave portion 23 so that the surface of the wiring board 22 facing the concave portion 23 is joined. Therefore, between the electronic cooling element 21 and the infrared detecting element 24. The thickness of the wiring board 22 interposed is small,
Therefore, the thermal resistance of this portion is small, and the cooling power of the electronic cooling element 21 can be more efficiently applied to the infrared detection element 24. Therefore, the infrared detection element 24 is cooled to a required cooling temperature without causing any trouble to the wiring (wiring for connecting the infrared detection element and the external circuit) and without causing the electronic cooling element 21 to become large. be able to. (2) Second Embodiment of the Present Invention FIG. 2 is a side view showing the configuration of the main part of the second embodiment of the present invention. In the figure, reference numeral 26 is an electronic cooling element utilizing the Peltier effect, and the electronic cooling element 26 is provided so as to come into contact with the inner wall of the lower case of the sealed case (not shown).

A wiring pattern 27 is formed on the infrared detection element mounting portion of the electronic cooling element 26. Reference numeral 28 denotes an infrared detection element (photoelectric conversion element for infrared detection). The infrared detecting element 28 is fixed on the electronic cooling element 26 with the back surface thereof being directly joined by an adhesive or the like.

The infrared detecting element 28 and the wiring pattern 27 on the electronic cooling element 26 are bonded and connected by a wire 29 such as gold. The infrared detection element 28 is bonded and fixed to a predetermined position of the electronic cooling element 26 as shown in FIG.
The upper opening of the lower case is closed by an upper lid having an infrared transmitting window at a predetermined position while accommodating the openings.
The infrared detecting element 28 and the circuit outside the case are connected to the wire 2
9, the wiring pattern 27 on the electronic cooling element 26 and other means (lead pins or the like) are used for connection.

According to the present embodiment, since the infrared detecting element 28 is directly bonded onto the electronic cooling element 26 having the wiring pattern 27 formed, the portion between the electronic cooling element 26 and the infrared detecting element 28 is formed. Has almost no thermal resistance, and the cooling power of the electronic cooling element 26 can be more efficiently applied to the infrared detection element 28. Therefore, the infrared detection element 28 is cooled to the required cooling temperature without causing any trouble in the wiring (wiring for connecting the infrared detection element and the external circuit) and without increasing the size of the electronic cooling element 26. be able to. (3) Third Embodiment of the Present Invention FIG. 3 is a sectional view showing the structure of a third embodiment of the present invention. In the figure, 31 is a sealed case, and the sealed case 31
Is composed of a lower case (base portion) 32 and an upper lid 33.

The lower case 32 is provided with a plurality of lead pins 34 so as to penetrate the bottom wall thereof. These lead pins 34 are airtightly provided by a method such as hermetic sealing. Further, a plurality of protrusions 35 projecting inward are arranged in an array at a portion slightly below the tip of the lead pin 34 on the side wall of the lower case 32. The protrusion 35 can be formed by pressing from the outside, or can be formed by fixing an independent member by welding or the like.

An electronic cooling element 36 utilizing the Peltier effect is provided in the substantially central portion of the bottom surface of the lower case 32 (two stages are shown in the same drawing, but one stage or more stages are also available. ) Is provided, and this electronic cooling element 36 is provided.
A wiring substrate 37 made of sapphire or the like having a wiring pattern formed thereon is adhered, and further an infrared detection element 38 is adhered. The infrared detection element 38 is generally the wiring board 3
It is mounted on the electronic cooling element 36 after undergoing evaluation of characteristics and the like in a state of being integrally fixed on 7.

Reference numeral 39 is a wiring board made of ceramics or the like on which a wiring pattern is formed.
5 and the lead pin 34. That is, the peripheral portion of the wiring board 39 is placed on the protrusion 35, and
The lead pins are fixed to the through holes of the wiring board 39 by soldering or the like while penetrating the tips of the lead pins. Corresponding portions of the protrusion 35 and the wiring board 39 can be fixed with an adhesive or the like, if necessary.

The infrared detecting element 38 and the wiring pattern on the wiring board 37 are connected by bonding with a wire (not shown) made of gold or the like, and the wiring patterns of the wiring board 37 and the wiring board 39 are also the wires 40. The wiring pattern of the wiring board 39 is soldered to the lead pins 34.

As a result, the infrared detecting element 38 includes the wires (not shown), the wiring pattern of the wiring board 37, the wires 40, the wiring pattern of the wiring board 39, and the lead pins 34.
Is connected to a circuit outside the case via.

The upper lid 33 of the case 31 is integrally provided with an infrared transmission window 41 near the center thereof. The lower case 32 and the upper lid 33 are hermetically assembled by welding the opposite joint portions 42 and the like.

According to this embodiment, the wiring board 39 is supported by the projections 35 on the side wall of the lower case 32 and the lead pins 39, and the infrared detection element 38 and the circuit outside the case are connected by the lead pins 39 and the wiring board 39. This is done through the wiring pattern and the like. Further, the number of constituent parts of the case 31 is the lower case 32 and the upper lid 33, which are smaller than those in the conventional case, and the number of the joints 42 is also smaller.

Regarding the mounting of the infrared detecting element 38 on the electronic cooling element 36, in this example, a structure similar to that of the conventional one shown in FIG. 7 is adopted.
It goes without saying that the structures shown in the examples can be adopted. (4) Fourth Embodiment of the Present Invention FIG. 4 is a sectional view showing the structure of a fourth embodiment of the present invention. This is a modification of part of the third embodiment, and only parts different from the third embodiment will be described.

That is, in the third embodiment, the lead pin 3
4 has a linear shape and is provided so as to penetrate the bottom wall of the lower case 32, but in this embodiment, the lead pin 43 is an L-shaped one bent at a substantially right angle. It penetrates through the side wall of.

By adopting the structure shown in this example according to the structure of the electronic cooling element 36, the infrared detector can be downsized. That is, in the third embodiment, a space for providing the lead pin is required on the bottom surface of the lower case 32, but this is not necessary in this example. (5) Fifth Embodiment of the Present Invention FIG. 5 is a diagram showing a configuration of a fifth embodiment of the present invention.
Is a plan view with the upper lid removed, and FIG.
This is a modification of part of the third embodiment, and the third embodiment
Only parts different from the embodiment will be described.

That is, in the third embodiment, the wiring board 39
Is supported by the projection 35 and the lead pin 34,
In this embodiment, the wiring board 3 is further provided by the getter support pins 44 and the electronic cooling element pins (lead pins) 45.
9 is supported.

The inside of the hermetically sealed case 31 is vacuum-sucked in order to keep the infrared detection element 38 at a predetermined cooling temperature. However, the degree of vacuum is deteriorated due to the release and leakage of gas from each member and the like. Is a getter (gas molecule sorption means)
46 is provided. While supporting the getter 46, the getter support pin 44 as a terminal for energizing the getter 46 also supports the wiring board 39.
The wiring board 39 is securely fixed.

The wiring board 39 can also be supported by the electronic cooling element pins (lead pins) 45 for energizing the electronic cooling element 36. If the number of getter support pins 44 and electronic cooling element pins 45 is appropriate, part or all of the support of the wiring board 39 by the lead pins 34 may be omitted. (6) Sixth Embodiment of the Present Invention FIG. 6 is a sectional view showing the structure of the sixth embodiment of the present invention. This is a modification of part of the third embodiment, and only parts different from the third embodiment will be described.

That is, a plurality of protrusions (second protrusions) 47 are provided near the inner peripheral edge of the upper lid 33. The protrusion 47 is arranged at a position substantially corresponding to the protrusion (first protrusion) 35 of the lower case 32, and the upper opening of the lower case 32 is covered with the upper lid 33.
When the wiring board 39 is closed by the protrusion 3 of the lower case 32,
The wiring board 39 is securely fixed by being sandwiched by the protrusions 5 and the protrusions 47 of the upper lid 33. In particular, it is effective as a vibration countermeasure.

[0035]

Since the present invention is configured as described above, it is possible to improve the cooling efficiency of the infrared detecting element. In addition, it is possible to reduce the size and cost of the infrared detector.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a first embodiment of the present invention.

FIG. 2 is a side view showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is a sectional view showing a configuration of a third exemplary embodiment of the present invention.

FIG. 4 is a sectional view showing a configuration of a fourth exemplary embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a fifth exemplary embodiment of the present invention,
(A) is a plan view with an upper lid removed, and (B) is a sectional view.

FIG. 6 is a sectional view showing the structure of a sixth embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a conventional configuration.

[Explanation of symbols]

 21 Electronic Cooling Element 22 Wiring Board 23 Recessed Section (Thin Section) 24 Infrared Detection Element 25 Wire 26 Electronic Cooling Element 27 Wiring Pattern 28 Infrared Detection Element 29 Wire 31 Sealed Case 32 Lower Case 33 Upper Lid 34 Lead Pin 35 Protrusion (First Protrusion) 36 Electronic cooling element 37 Wiring board 38 Infrared detection element 39 Wiring board 40 Wire 41 Infrared transmission window 42 Joining part (welding part) 43 Lead pin 44 Getter support pin 45 Electronic cooling element pin 46 Getter 47 Projection (second projection)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomofumi Ueda 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Shigeki Hamajima 1015, Kamiodanaka, Nakahara-ku, Kawasaki, Kanagawa Within Fujitsu Limited

Claims (8)

[Claims] 1. An electronic cooling element (21) provided in a sealed case in contact with an inner wall of the case, and the electronic cooling element (21).
In an infrared detector containing an infrared detection element (24) cooled by, the infrared detection element (24), the thin surface portion of the concave portion (23)
And the wiring board (22) provided in contact with the bottom surface of the thin portion (23) of the wiring board (22) having a pattern for connecting the infrared detection element (24) to a circuit outside the case. )
An infrared detector characterized in that the back side is joined to the electronic cooling element (21). 2. An electronic cooling element as a cooling means for an infrared detecting element, characterized in that a wiring pattern (27) is provided on a surface to which the infrared detecting element (28) is joined. . 3. A case (31) comprising a lower case (32) having an opening on the upper surface and an upper lid (33) having an infrared transmitting window (41) for sealing the opening of the lower case (32), Infrared detecting element (38) provided at a predetermined position, a plurality of lead pins (34, 43, 45) provided through the wall of the lower case (32), and lead pins (34, 43, 45) And a wiring board (39) having a wiring pattern for electrically connecting the infrared detection element (38) and the lead pin (34) while being supported in the vicinity of the infrared detection element (38) by A featured infrared detector. 4. The infrared detector according to claim 3, further comprising a support pin (44) that is not connected to an infrared detection element that is provided through the wall of the lower case (32), An infrared detector (39) is also supported by a support pin (44). 5. The infrared detector according to claim 3, wherein at least one first protrusion (35) provided on the inner wall of the lower case (32) and the first protrusion (35) of the lower case (32). 35) corresponding to the above case
The upper lid (33) of the (31) is provided with a second protrusion (47), the wiring board (39), the first protrusion (35) and the second protrusion (47)
An infrared detector characterized by being fixed by being sandwiched by. 6. The infrared detector according to claim 1, wherein the wiring board (22) is made of sapphire or borosilicate glass. 7. An infrared detector characterized in that an infrared detecting element (28) is joined to an electronic cooling element (26) provided with the wiring pattern (27) according to claim 2. 8. The infrared detector according to claim 3, wherein the wiring board (39) is at least one of the inner walls of the lower case (32).
An infrared detector characterized by being supported by one or more protrusions (35) and the lead pin (34).