JPH08128890A - Infrared sensor - Google Patents

Abstract

PURPOSE: To provide an infrared sensor wherein the occurrence of noise by an outside electromagnetic wave is small and whose effective manufacture can be performed at low cost. CONSTITUTION: At least a part of a thermoplastic resin 29 having conduction making a purpose of an electromagnetic shield and at least a part of a cross section of an optical filter 27 composed of an interference film formed on both the faces of a silicon plate are bonded by epoxy resin which makes main structure of bisphenol A. As a result, a resistance value between an outer resin and an optical filter is small, and a piece difference by samples can be reduced. Material cost can be reduced and a process of painting-hardening of a conductive bonding agent can be eliminated because the conductive bonding agent is not completely used. An infrared sensor having stable shield performance at a low price is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared sensor used for human body detection, disaster detection for disaster prevention, temperature measurement and the like.

[0002]

2. Description of the Related Art Conventionally, infrared sensors have been widely used for human body detection of automatic doors, automatic flushing devices for toilets, lighting equipment, air conditioning equipment, security equipment, disaster detection for disaster prevention, temperature measurement, and the like. The conventional infrared sensor will be described below.

FIG. 10 is a side sectional view of a conventional pyroelectric infrared sensor. In FIG. 10, a field effect transistor (hereinafter abbreviated as FET) 3, a resistor 4, and an infrared detection element 5 are fixed to an insulating circuit board 2 that penetrates an external lead-out pin 1, and the circuit board 2 is led out to the outside. Attach to pin 1. Then, the metal case 6 having the infrared introducing hole 6a is sealed to the hermetic base 7. The infrared introducing hole 6a of the metal case 6 is provided with an optical filter 8 composed of an interference film formed on both surfaces of a silicon plate that transmits only a desired wavelength region. The surface 8a of the optical filter 8 has no electrical conduction. Since it is difficult to obtain, a part of the cut surface 8b is connected with the conductive adhesive 9. By electrically connecting the metal case 6 and the optical filter 8, the electromagnetic shield effect of the optical filter portion is improved. In order to further enhance the airtightness, an insulating adhesive 10 is applied along the outer edge of the optical filter so as to cover the conductive adhesive.

FIG. 11 is a side sectional view of another conventional pyroelectric infrared sensor. The pyroelectric infrared sensor was proposed for the purpose of reducing the package cost and simplifying the construction method. In FIG. 11, a lead frame 11 that also serves as an external lead-out pin and an internal circuit board, a resistor 12 and an FET 13 that are electrically and mechanically connected to the lead frame 11 are integrally molded with an insulating resin 14, and are further electromagnetically shielded. An element output take-out terminal 16 is used by using a case molded with the intended exterior resin 15 having conductivity.
After connecting the infrared detecting element with a conductive adhesive, the surface 17a of the optical filter 17 made of the interference film formed on both surfaces of the silicon plate is cut with the insulating resin 14 by the insulating adhesive. The surface 17b is connected to the exterior resin 15 having conductivity using a conductive resin.

[0005]

However, in the above-mentioned conventional structure, a large amount of conductive adhesive is required to obtain stable conduction between the optical filter and the outer package, which leads to an increase in material cost. Insulating adhesive is also applied,
An extra step for curing is required, and further, the insulating adhesive and the conductive adhesive are contact-reacted with each other, which may cause insufficient conduction, resulting in a large variation in the electromagnetic shielding effect. Had a point.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an infrared sensor having a stable electromagnetic shield effect at low cost and in a small number of steps.

[0007]

To achieve this object, at least a part of a thermoplastic exterior molding resin having conductivity for the purpose of electromagnetic shielding, a silicon plate and an interference film formed on both surfaces thereof are used. At least a part of the cut surface of the optical filter was bonded with an epoxy adhesive containing bisphenol-A as a main structure.

[0008]

With the above construction, the electric resistance between the exterior resin and the optical filter is small and stable, so that a stable electromagnetic shield effect can be obtained. Further, since the conductive adhesive is not used at all, the material cost can be reduced, and the steps of applying and curing the conductive adhesive can be reduced.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of an infrared sensor according to the first embodiment of the present invention. In FIG.
Is a resistor provided in parallel with the infrared detection element 18, and the resistor 19 is provided for current stabilization. 20 is an FET.

FIG. 2 is a partial perspective view of an infrared sensor according to the first embodiment of the present invention, FIGS. 3 and 4 are the same perspective views, and FIG.
FIG. In FIG. 2, 21 is a lead frame, and the lead frame 21 includes a pair of bases 21a,
Connecting portions 21b, 2 provided across the pair of bases 21a
1c and extended portions 21d and 21e extended from a pair of bases 21a, respectively.

The connecting portions 21b and 21c each have an element mounting portion 21 projecting in a direction facing each other.
f and 21g are provided, and the element mounting portion 2 is further provided.
1f and 21g are provided with joints 21h and 21i standing upright in the same direction. The resistor 19 is joined to both the element mounting portion 21g and the connecting portion 21b by soldering or the like, and the FET 20 includes the portion forming the element mounting portion 21g of the connecting portion 21c and the extending portions 21d and 21e.
Are similarly joined to each other with solder or the like.

Next, the lead frame 21 is cut along the dotted line shown in FIG. That is, both ends of the connecting portion 21b are cut, the connecting portion 21c is cut so that only the central portion of the connecting portion 21c is left, and both end portions of the extending portions 21d and 21e are cut. In this way, the portion on which the semi-finished electronic component mounted with the unnecessary portion cut is mounted is covered with a material having weather resistance or the like. This work is integrally molded with the insulating resin 23 by a transfer molding machine into a shape as shown in FIG. 3, for example.
At this time, the pair of output terminals 22 connected to the external lead-out leads 24 a and 24 b, which are a part of the lead frame 21, and the infrared detection element 18 are not covered with the insulating resin 23. Further, a concave portion 26 into which the element is inserted is formed.

At this time, the external lead-out lead 24c is formed by cutting the connecting portion 21b shown in FIG. 2, and the external lead-out leads 24a and 24b are extended portions 21c and 21c, respectively.
It is configured by cutting 21d. The pair of output terminals 22 are connected to the semi-finished product joints 21h,
21i. In addition, external lead-outs 24a, 24
Of the b and 24c, a molding step 25 is provided at the root of each of the external lead 24a serving as a drain lead and the external lead 24b serving as a source lead.

Next, the outer peripheral portion of the insulating resin 23 is coated with the conductive thermoplastic resin 29 on the insulating resin 23 using an injection molding machine (FIG. 4). As the conductive thermoplastic resin 29, a material such as a resin containing polycarbonate as a main component and having conductive carbon fiber and having a specific resistance of 10 ^-1 Ωcm was used.
FIG. 4 shows a shape after the conductive thermoplastic resin 29 is formed. At this time, the thermoplastic resin 29 having conductivity
No output is obtained when the external lead-out leads 24a, 24b are brought into contact with the external lead-out leads 24a, 24b. Therefore, the thermoplastic resin 29 having conductivity must be constructed so as not to come into contact with the external lead-out leads 24a, 24b. The two external lead-outs 24c serve as ground terminals and are electrically connected to the thermoplastic resin 29 having conductivity. Further, a thermoplastic resin 29 having conductivity
Is not provided in the recess 26, but a filter insertion frame 30 larger than the outer edge of the recess 26 is provided.

Next, in the side sectional view of FIG. 5, the infrared detecting element 18 is electrically and mechanically connected to the output terminal 22 in the recess 26 by using a conductive adhesive, and is formed on the silicon plate and both surfaces thereof. Optical filter 27 consisting of an interference film
Bottom surface 27b of the resin and the upper surface 23b of the insulating resin 23, and the cut surface 27a of the optical filter 27 and the inner surface 29a of the filter provided on the thermoplastic resin 29 having conductivity are epoxy adhesives containing bisphenol-A as a main component. Adhere with to obtain an infrared sensor.

The conductive thermoplastic resin 29 may be made of a resin such as ABS or polystyrene containing fibers such as copper and stainless steel. However, the resin containing these metal fibers is thin. The shape is difficult to form, and the conduction between the conductive thermoplastic resin 29 and the optical filter 27 is worse than that using the carbon fiber, which is not preferable.

Ten infrared sensors were manufactured by the above method, the resistance value between the optical filter 27 and the external lead-out terminal was measured, and the average value: X and the standard deviation: σ _n were calculated. Since electrical conductivity cannot be directly obtained from the surface of the optical filter 27, the insulating interference film on the surface of the optical filter 27 is cut and removed, and then the resistance value is measured between the central portion of the optical filter 27 and the tip of the ground terminal. did. The obtained results are shown in (Table 1). For comparison, the infrared sensor according to the conventional example shown in FIG. 10 is used as Comparative Example 1 and the infrared sensor shown in FIG. 11 is used as Comparative Example 2, and the resistance value between the optical filter 27 and the ground terminal is measured by the same method to obtain the result. It shows in (Table 1).

[0018]

[Table 1]

As is clear from (Table 1), the infrared sensor according to the present embodiment has a smaller resistance between the optical filter 27 and the ground terminal than the conventional sensor, and has a very small difference between the samples. This means that a stable shielding property of the filter portion can be obtained as a function of the sensor.

In the present invention, stable and sufficient electrical continuity between the optical filter 27 and the ground can be obtained without using a conductive adhesive when the epoxy adhesive containing bisphenol-A as a main component is reacted and cured. As a result of the fact that the surface of the thermoplastic resin is attacked and the conductive material inside is taken into the epoxy adhesive side, stable conduction at the adhesive interface can be obtained.

6 and 7 are side sectional views of an infrared sensor according to the second embodiment of the present invention. In FIG. 6, the FET 33 and the resistor 34 are soldered to the insulative substrate 32 that penetrates the external lead-out pin 31a of the hermetic base 31, and the infrared detection element 35 is electrically and mechanically connected by a conductive adhesive. . The board 32 is soldered to the external lead-out pin 31a to form a sensor base.

In FIG. 7, a light introducing hole is formed in the thermoplastic resin 36 having conductivity, and the thermoplastic resin 36
The portion 36a facing the introduction hole of 1 and the cut surface 37a of the optical filter 37 are bonded with an epoxy adhesive containing bisphenol-A as a main component to form a sensor cap. Further, the outer edge portion 31b of the hermetic base 31 in FIG. 6 and the bottom portion 36b of the conductive thermoplastic resin 36 in FIG. 7 are bonded with an epoxy adhesive containing bisphenol-A as a main component to obtain an infrared sensor. Ten infrared sensors were manufactured by the above method, and the resistance value between the optical filter 37 and the externally derived ground terminal was measured by the same method as in Example 1, and the results are shown in (Table 1). Similar to the first embodiment, as is clear from (Table 1), the infrared sensor according to this embodiment has a smaller resistance between the optical filter 37 and the ground terminal than the conventional sensor, and the individual difference due to the sample is extremely small.

FIG. 8 is a side sectional view of an infrared sensor according to the third embodiment of the present invention. In FIG. 8, the thermoplastic resin 36 having conductivity is provided with a light introducing hole and a recess for inserting the optical filter 37 in the light receiving surface. The outer peripheral surface 36a of the recess and the cut surface 37a of the optical filter 37 are Further, the lower surface 36b of the concave portion of the thermoplastic resin 36 and the bottom surface 37b of the optical filter 37 are bonded with an epoxy adhesive containing bisphenol-A as a main component to form a sensor cap. Further, the outer edge portion 31b of the hermetic base 31 in FIG.
Then, the bottom portion 36b of the thermoplastic resin 36 having conductivity shown in FIG. 8 is bonded with an epoxy adhesive containing bisphenol-A as a main component to obtain an infrared sensor.

Ten infrared sensors were manufactured by the above method, and the resistance value between the optical filter 37 and the external lead-out terminal was measured by the same method as in Example 1, and the results are shown in (Table 1). . Similar to the first embodiment, as is clear from (Table 1), the infrared sensor according to this embodiment has a smaller resistance between the optical filter 37 and the ground terminal than the conventional sensor, and the individual difference due to the sample is extremely small.

FIG. 9 is a side sectional view of an infrared sensor according to the fourth embodiment of the present invention. In FIG. 9, a thermoplastic resin 36 having conductivity is provided with a light introducing hole and a recess for inserting the optical filter 37 on the back surface of the light receiving surface. The outer peripheral surface 36a of the recess and the cut surface 37a of the optical filter 37 are formed.
And the bottom surface 36b of the concave portion of the thermoplastic resin 36 and the bottom surface 37b of the optical filter 37 are bonded with an epoxy adhesive containing bisphenol-A as a main component to form a sensor cap. Further, the outer edge portion 31b of the hermetic base 31 shown in FIG. 6 and the thermoplastic resin 3 having conductivity shown in FIG.
The bottom portion 36b of 6 is bonded with an epoxy adhesive containing bisphenol-A as a main component to obtain an infrared sensor.

Ten infrared sensors were manufactured by the above method, and the resistance value between the optical filter and the external lead-out ground terminal was measured by the same method as in Example 1, and the results are shown in (Table 1). Similar to the first embodiment, as is clear from (Table 1), the infrared sensor according to this embodiment has a smaller resistance between the optical filter and the ground terminal than the conventional sensor, and the individual difference due to the sample is extremely small.

[0027]

As described above, the present invention is an optical filter comprising at least a part of a conductive thermoplastic exterior molding resin for the purpose of electromagnetic shielding, a silicon plate and an interference film formed on both surfaces thereof. By bonding at least a part of the cut surface with an epoxy resin having bisphenol-A as a main structure, the resistance value between the exterior resin and the optical filter is small, and individual differences due to the sample can be reduced. Further, since the conductive adhesive is not used at all, the material cost can be reduced, and the steps of applying and curing the conductive adhesive can be eliminated, and an infrared sensor having a stable shield performance at a low price can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an infrared sensor according to a first embodiment of the present invention.

FIG. 2 is a partial perspective view of an infrared sensor according to the first embodiment of the present invention.

FIG. 3 is a perspective view of an infrared sensor according to the first embodiment of the present invention.

FIG. 4 is a perspective view of an infrared sensor according to the first embodiment of the present invention.

FIG. 5 is a side sectional view of the infrared sensor according to the first embodiment of the present invention.

FIG. 6 is a side sectional view of an infrared sensor according to a second embodiment of the present invention.

FIG. 7 is a side sectional view of an infrared sensor according to a second embodiment of the present invention.

FIG. 8 is a side sectional view of an infrared sensor according to a third embodiment of the present invention.

FIG. 9 is a side sectional view of an infrared sensor according to a fourth embodiment of the present invention.

FIG. 10 is a side sectional view of a conventional pyroelectric infrared sensor.

FIG. 11 is a side sectional view of another conventional pyroelectric infrared sensor.

[Explanation of symbols]

 18 Infrared detecting element 21 Lead frame 23 Insulating resin 27, 37 Optical filter 27a, 37a Cut surface 29, 36 Thermoplastic resin 31 Hermetic base 32 Substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Watanabe 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (11)

[Claims] 1. At least a part of a conductive thermoplastic exterior molding resin for electromagnetic shielding, and at least a part of a cut surface of an optical filter composed of a silicon plate and an interference film formed on both surfaces thereof are covered with bisphenol. An infrared sensor characterized by being bonded with an epoxy resin having a main structure of -A. 2. The infrared sensor according to claim 1, wherein a material in which carbon fibers are dispersed in polycarbonate is used as the thermoplastic exterior molding resin. 3. At least one or more of the circuit components excluding the infrared detecting element, an insulating resin portion integrally molded with a part of a lead electrically and mechanically connecting them and leading out to the outside, and this insulating property. The case has a lead case made of a conductive thermoplastic exterior molding resin that further molds at least a part of the resin part, the infrared detection element built into this case, and the interference formed on both sides of the silicon plate. An infrared sensor composed of an optical filter made of a film, wherein an interference film surface of the optical filter is an insulating resin portion, a cut surface of the optical filter is an exterior molding resin having conductivity, and bisphenol-A is respectively added. The infrared sensor according to claim 1, wherein the infrared sensor is bonded with an epoxy resin as a main structure. 4. The infrared sensor according to claim 3, wherein a material in which carbon fibers are dispersed in polycarbonate is used as the thermoplastic exterior molding resin. 5. The infrared sensor according to claim 3, wherein an epoxy resin is used as the insulating resin material. 6. An infrared detection element and a circuit component, and a sensor base with leads for mechanically connecting and electrically leading them, and light introduction to a part separately connected to the structure. A thermoplastic molded resin case having a hole having conductivity, and an optical filter composed of an interference film formed on both surfaces of a silicon plate, and a bisphenose-shaped inner surface of the light introduction hole and a cut surface of the optical filter. The infrared sensor according to claim 1, wherein the infrared sensor is bonded with an epoxy resin having A as a main structure. 7. The infrared sensor according to claim 6, wherein a material in which carbon fibers are dispersed in polycarbonate is used as the thermoplastic molded resin case. 8. An infrared detection element and a circuit component, a sensor base with leads for mechanically connecting and electrically leading them, and a part of the base separately connected to the structure for introducing light. A thermoplastic molding resin case having a hole provided with conductivity, and an optical filter composed of an interference film formed on both surfaces of a silicon plate, and a concave portion is formed on the light-receiving surface of the thermoplastic molding resin case. The infrared sensor according to claim 1, wherein the optical filter is bonded with an epoxy resin having bisphenol-A as a main structure. 9. The infrared sensor according to claim 8, wherein a material in which carbon fibers are dispersed in polycarbonate is used as the thermoplastic molded resin case. 10. An infrared detection element and a circuit component, and a sensor base with leads for mechanically connecting and electrically leading them, and light introduction to a part separately connected to the structure. A thermoplastic molding resin case having conductivity provided with a hole, and an optical filter consisting of an interference film formed on both sides of a silicon plate, a recess is formed on the light receiving surface facing side of the thermoplastic molding resin case, The infrared sensor according to claim 1, wherein an optical filter is bonded thereto with an epoxy resin having bisphenol-A as a main structure. 11. The infrared sensor according to claim 10, wherein a material in which carbon fibers are dispersed in polycarbonate is used as the thermoplastic molded resin case.