JPS6351494B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a pyroelectric infrared detector.

Normally, pyroelectric pellets that generate electric charge according to the amount of change in incident infrared rays have the characteristic that the smaller their dissipated heat, the higher the output and the better the signal-to-noise ratio. In the detector, the pellet was suspended and insulated. However, the thickness of pyroelectric pellets is several tens of μm.
Because it is extremely thin and has a small shape of only a few millimeters square,
As mentioned above, when the detector is suspended in the air, it is difficult to handle and the mass productivity of the detector is low.

Therefore, recent detectors have a structure in which a pyroelectric pellet is adhered to the upper surface of a support base having a recessed portion using an epoxy adhesive to support the pellet. Since the pellets are sufficiently insulated due to the presence of the recesses, the heat dissipated from the pellets is kept to an extremely low level.

FIG. 1 shows such a pyroelectric infrared detector, particularly a pyroelectric infrared detector used in a detection section of an intruder alarm.

1 is a pyroelectric pellet formed from lithium tantalate (LiTaO ₃ ) crystal, etc., which generates a charge according to the amount of change in incident infrared rays; 2 and 3 are the above pellets formed by vacuum evaporation of nichrome (Ni-Cr), respectively. The front electrode 2 consists of first and second front electrodes 2a and 2b which are separated from each other and have the same shape, and the back electrode 3 is formed on the entire back surface of the pellet 1. There is. 4a and 4
Reference characters b denote first and second pads for ultrasonic bonding the first and second lead wires 5a and 5b to the first and second surface electrodes 2a and 2b, respectively, and the first and second pads are made of aluminum, respectively. It is made of a vacuum-deposited film such as and provided at the corners of the first and second surface electrodes 2a and 2b.

Note that the first lead wire 5a is grounded, and an output is obtained from the second lead wire 5b.

6 is a support made of phosphor bronze, etc., and 7 is an acid-etched top surface of the support with a depth of 0.1 to 0.2 mm.
The pellet 1 is sufficiently insulated by the recess, and the heat dissipated from the pellet 1 is suppressed to an extremely low level. 8 is an epoxy adhesive.

Therefore, in the front of the pyroelectric pellet 1,
When the human body passes as shown by arrow A, pellet 1
The amount of incident infrared rays changes based on the infrared rays emitted from the human body on the first surface electrode 2a side. Then, a charge is generated on the first surface electrode 2a side of the pellet 1, and a signal due to the charge is led out from the second lead line 5b via the back surface electrode 3 and the second surface electrode 2b. Next, the second surface electrode 2b of the pellet 1
The amount of incident infrared rays changes on the side. In such a case, the signal is similarly led out from the second lead line 5b. Then, based on these signals, an alarm is issued from the intruder alarm.

Incidentally, the pellet 1 receives infrared rays from sunlight as well, but in this case it does not output any signal. In other words, the infrared rays from sunlight etc. are incident on the entire surface of the pellet 1 at the same time in equal amounts,
Equal charges are simultaneously generated on the first and second surface electrodes 2a and 2b of the pellet 1, and therefore, these charges cancel each other out, so that no signal is output from the second lead line 5b.

Next, a manufacturing method for obtaining the above detector will be explained with reference to FIG. First, as shown in Figure 2a,
A wide-area support base original plate 6' that will eventually be divided into support bases 6 is prepared. A large number of recesses 7, 7, . . . are formed in advance at equal intervals on the upper surface of the original plate by acid etching.

Then, as shown in FIG. 2b, an epoxy adhesive 8 is applied only to the upper surface of the original plate 6' other than the recesses 7, 7, . A 0.2 mm pyroelectric wafer 1' is placed with the back electrode 3' facing down, and then the adhesive 8 is cured by heating.

Next, as shown in FIG. 2C, after polishing the surface of the wafer 1' to make the thickness of the wafer 1' several tens of μm,
First surface electrodes 2a, 2a, . . . and second surface electrodes 2b, 2b, . After that, the first surface electrode 2
First leader lines 5a, 5a... and second leader lines 5b, 5 are attached to a, 2a... and second surface electrodes 2b, 2b, respectively.
If b... is subjected to ultrasonic bonding, a large quantity of detectors as shown in FIG. 1 can be obtained.

Here, in the step of applying the adhesive 8 to the upper surface other than the recesses 7, 7, etc. of the original plate 6', if the amount of adhesive applied is too large, the adhesive 8 will be spread horizontally when the wafer 1' is placed next. It sticks out and adheres over a wide area to the portions of the back electrode 3' that are opposed to the recesses 7, 7, . . . .

Then, the heat insulating effect of the pellet 1 in the detector deteriorates, and the S/N ratio of the pellet 1 decreases significantly.
Furthermore, such an adhesive 8 generally generates static electricity which becomes noise, and therefore, when the adhesive 8 is adhered to a wide area as described above, the SN ratio of the pellet 1 is significantly lowered from this point as well.

The present invention has been made in view of this point, and a method for manufacturing a pyroelectric infrared detector according to an embodiment of the present invention will be described below with reference to FIGS. 3 and 4. Note that the same parts as in FIGS. 1 and 2 are denoted by the same reference numerals, and the explanation thereof will be omitted.

First, as shown in FIG. 3a, a support base plate 6' is prepared. A large number of pillars 9, 9... are formed in advance on the upper surface of the original plate by acid etching at predetermined intervals in the vertical and horizontal directions, and each of the pillars 9, 9... has cross-shaped grooves 10, 10... in the vertical and horizontal directions. is formed by acid etching.

For example, the vertical interval m and the horizontal interval n of each of the above-mentioned supports 9, 9... are 2 mm and 3 mm, respectively.
The radius r and height h of the pillars 9, 9... are 1.4 mm and 0.1 to 0.15 mm, respectively, and the groove 1
The width w and depth d of 0, 10... are 0.25 mm and 0.25 mm, respectively.
It is 0.1~0.15mm.

Next, as shown in FIG. 3b, epoxy adhesive 8 is applied only to the upper surface of the pillars 9, 9 of the original plate 6', and the pyroelectric wafer 1' is placed thereon with the back electrode 3' facing down. Place it like this.

Here, since the total area of the supporting end surfaces of the columns 9, 9... is extremely small, even if the amount of adhesive 8 applied to the supporting end surfaces of the columns 9, 9... is too large, the amount will be smaller than before. Very little, and moreover, when the wafer 1' is next placed on the supporting end surfaces of the supports 9, 9,
Most of the excess adhesive 8 flows into the grooves 10, 10, . . . for draining and dividing the excess adhesive. Therefore, when the wafer 1' is placed in this manner, the adhesive 8 protrudes outside the supporting end surfaces of the support columns 9, 9, and damages the back electrode 3'.
The area of attachment other than the portions facing the pillars 9, 9, .

After that, the adhesive 8 is heated and cured.

Next, as shown in FIG. 3C, after polishing the surface of the wafer 1' to make the thickness of the wafer 1' several tens of μm,
First surface electrodes 2a, 2a, . . . and second surface electrodes 2b, 2b, . . . are vacuum deposited on the surface of the wafer 1'. After that, as shown by the dashed line, the grooves 10, 10...
The wafer 1', original plate 6', etc. are diced at the position passing through. Then, the first lead wires 5 are connected to the first surface electrodes 2a, 2a... and the second surface electrodes 2b, 2b..., respectively.
A, 5a, . . . and second lead wires 5b, 5b are subjected to ultrasonic bonding to obtain a large quantity of detectors as shown in FIG.

Although the pillars 9, 9, . . . are circular in the above embodiment, they may be square.

As is clear from the above description, according to the present invention, there is a step of forming struts having grooves at predetermined intervals in the vertical and horizontal directions on the main surface of the support base plate, and after applying an adhesive to the supporting end surface of a small area of the struts. , a step of placing a pyroelectric wafer on the supporting end surfaces of a plurality of support columns and adhering the wafer, and a step of dividing the pyroelectric wafer and the support base plate at positions passing through the grooves,
The mass productivity of the detector can be significantly improved.

Furthermore, since the pyroelectric wafer can be almost lifted off the support plate and the adhesion of adhesive to the pyroelectric wafer side can be sufficiently suppressed, the SN ratio of the pyroelectric pellets in mass-produced detectors can be significantly reduced. You can improve.

[Brief explanation of the drawing]

Figure 1a is a perspective view of a conventional pyroelectric infrared detector, Figure 1b is a perspective view of the same essential parts, and Figures 2a, b, and c.
are a perspective view, a cross-sectional view, and a cross-sectional view to show the same manufacturing process, respectively.
3A, 3B, and 3C are respectively a perspective view, a sectional view, and a sectional view showing the manufacturing process of a pyroelectric infrared detector according to an embodiment of the present invention, and FIG. 4A is a perspective view of the same detector. , FIG. 4b is a perspective view of the same essential parts. 6'...supporting base plate, 1'...pyroelectric wafer,
9,9...post, 10,10...groove.

Claims (1)

[Claims] 1. A step of forming a plurality of columns having grooves for draining and dividing excess adhesive on the main surface of the original support plate at predetermined intervals in the vertical and horizontal directions, and after applying adhesive to the supporting end surface of a small area of the columns, The present invention is characterized by comprising the steps of: placing an electric wafer on the supporting end surfaces of the plurality of supports and adhering the wafer; and dividing the pyroelectric wafer and the support base plate at positions passing through the grooves. A method for manufacturing a pyroelectric infrared detector.