JPH10153616A - Acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the acceleration sensor, which is mounted on a printed circuit board together with other circuit elements, can apply a coating agent at the same time and can perform the efficient mounting work. SOLUTION: A second space B at the upper side of a silicone gel 8 convering one surface of a thin part 6a of a pressure sensitive element 6 and first space A formed at the other surface of the thin part 6a are communicated through an air hole 10a, a path 2c, a recess part 2b, a path 2d, an air hole 10b and a path 5a. Therefore, even if the first and second spaces A and B are tightly closed to the outside, the thin part 6a of the pressure sensitive part 6 can be bent and vibrated without suppression to the upper and lower directions. Thus, an acceleration sensor 1 can detect the acceleration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor, and more particularly to a diaphragm type acceleration sensor using a gel composition as an inertial body.

[0002]

2. Description of the Related Art The present applicant has proposed various diaphragm type acceleration sensors using a gel composition as an inertial body.
FIG. 4 shows a cross section of a main part for describing an example of the acceleration sensor. The acceleration sensor 50 has a cylindrical case 52 placed and fixed on a printed circuit board 51, and a ventilation hole 53 is provided at a central position of the substrate 51 surrounded by the case 52.
Are formed, and a diaphragm-type semiconductor pressure-sensitive sensor chip, that is, a pressure-sensitive element 54 is bonded and fixed with an adhesive so as to close the ventilation hole 53. Pressure sensing element 54
The bottom of the base material is cut out in a truncated pyramid shape, and the space formed by the cutout communicates with the ventilation hole 53.
The thin portion 54a above the hollowed portion functions as a diaphragm, and a diffusion strain gauge 54b is formed on the upper surface of the thin portion 54a. The case 52 to which the pressure-sensitive element 54 is fixed is filled with a silicone gel 55 which is a gel composition as an acceleration transmission medium so as to cover the element 54. A cap 56 is mounted on the upper part of the case 52 to prevent dust from entering the case 52.

When acceleration is applied to the sensor 50, pressure propagates to the pressure-sensitive element 54 via the silicone gel 55. In the pressure sensing element 54, the thin portion 54a bends and vibrates relative to the magnitude of the received pressure, and outputs an electric signal.

[0004]

The acceleration sensor 50 is used by being mounted on a printed circuit board 51 together with other circuit elements 57 such as ICs, resistors, and capacitors. The printed circuit board 51 on which the various circuit elements 57 are mounted is coated with a coating agent to protect the mounted circuit elements 57 and the like. This application method
Generally, this is performed by immersing the printed circuit board 51 in a tank storing the coating liquid.

At this time, the acceleration sensor 50 is
Is formed, when the printed circuit board 51 is immersed in the coating liquid, the air holes 53 are clogged, or the pressure-sensitive element 54 is hollowed out in a truncated square pyramid shape through the air holes 53. The coating liquid penetrates into. As a result, the pressure sensing element 54 cannot function as a sensor.

Therefore, conventionally, the printed circuit board 51 excluding the acceleration sensor 50 is immersed in a coating solution to form a protective film, and then the acceleration sensor 50 is mounted on the printed circuit board 51. Therefore, the acceleration sensor 50 must be mounted on the printed circuit board 51 in a later step, and the work efficiency is very poor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to efficiently mount a semiconductor device on a printed circuit board together with other circuit elements by applying a coating agent together. An object of the present invention is to provide an acceleration sensor capable of performing work.

[0008]

According to a first aspect of the present invention, a thin portion is formed with an acceleration transmitting medium housed in a case, one surface of which is covered with the acceleration transmitting medium and the other surface is covered with a thin portion. And a pressure-sensitive element for detecting an acceleration by bending and vibrating the thin portion in the acceleration transmission medium that forms and vibrates and vibrates based on an externally applied acceleration. The gist of the invention is that ventilation means is provided which is isolated from the outside air and communicates the first space with the second space above the acceleration transmitting medium in the case.

According to a second aspect of the present invention, in the acceleration sensor according to the first aspect, the pressure-sensitive element is fixed on a lead, and a recess is formed in a sealing resin material for sealing the lead. The case is placed and fixed on the lead of the concave portion, and the ventilation means extends vertically in a side wall of the case, and a passage communicating with the second space at an upper portion thereof, and a passage in the sealing resin material. A first ventilation hole communicating from the first space to a lower portion of the lead, and a second ventilation hole communicating from the lower portion of the passage of the case to the lower portion of the lead in the sealing resin material;
The gist is that the sealing resin material includes a communication hole that communicates the first air hole and the second air hole.

According to a third aspect of the present invention, in the acceleration sensor according to the second aspect, a detection signal of the acceleration detected by the pressure-sensitive element is amplified on a lead sealed with the sealing resin material. The gist of the present invention is that an integrated circuit device is provided.

According to the first aspect of the present invention, the first space formed on the other surface of the thin portion of the pressure-sensitive element and the second space above the acceleration transmission medium communicate with each other by the ventilation means. .
Also, the ventilation means is isolated from the outside air. Therefore, the thin portion of the pressure-sensitive element can bend and vibrate, and the acceleration sensor can detect the acceleration. Moreover, the coating agent can be applied together with the other circuit elements while being mounted on the printed circuit board.

According to the second aspect of the present invention, a passage extending in the vertical direction in the side wall of the case and communicating with the second space is formed at an upper portion thereof. The passage communicates with the first space via a first ventilation hole, a passage hole, and a second ventilation hole in the sealing resin material. Therefore, the ventilation means having a closed structure can be formed without providing another member for communicating the first space and the second space.

According to the third aspect of the present invention, since the pressure-sensitive element and the integrated circuit device are provided on the same lead and are sealed with the sealing resin material, the detection signal detected by the pressure-sensitive element is The signal is amplified and output by the integrated circuit device.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional side view of a main part showing an acceleration sensor according to the present embodiment. FIG. 2 is a plan view showing the acceleration sensor according to the present embodiment.

In FIG. 1, an acceleration sensor 1 has an integrated circuit device (IC) 4 constituting an amplifier circuit for amplifying a detection signal adhered on a die pad portion of a lead 3 sealed with a sealing resin material 2. Have been. A first concave portion 2a for mounting the sensor body is formed on one side of the upper surface of the acceleration sensor 1, and the surface of the lead 3 is exposed on the bottom surface thereof. A cylindrical case 5 is fitted and fixed to the first concave portion 2a. A die pad portion 3a of the lead 3 is exposed at the center surrounded by the case 5, and a diaphragm-type semiconductor pressure-sensitive sensor chip, that is, a pressure-sensitive element 6, is bonded and fixed to the die pad portion 3a with an adhesive. .

The pressure-sensitive element 6 is formed by cutting a bottom of the base material into a truncated pyramid shape, and a space A is formed by the cut-out. The thin portion 6a above the hollowed portion functions as a diaphragm, and a plurality of diffusion strain gauges 6b are formed on the upper surface of the thin portion 6a. Each diffusion strain gauge 6b is connected to each lead 3 by a bonding wire 7, and is connected to the input side of the IC 4. Also IC
Each terminal 4 is connected to a lead pin 3b extending downward from the sealing resin material 2.

In the case 5 to which the pressure-sensitive element 5 is fixed,
Silicone gel 8, which is a gel composition as an acceleration transmission medium, is filled to a predetermined position so as to cover the element 6. A cap 9 for preventing dust from entering the case 5 is attached to an upper portion of the case 5. As shown in FIG. 2, the case 5 has a cylindrical shape with a part of its wall swelling, and a passage 5a is formed in the swelling part. When the cap 9 is attached, the case 5 And the space B above the silicone gel 8 are formed so as to communicate with each other.

The die pad portion 3a of the lead 3 to which the pressure-sensitive element 6 is fixed has a first ventilation hole 10a communicating with the hollow A. Further, a second ventilation hole 10b communicating with the passage 5a is formed in the die pad portion 3a of the lead 3 corresponding to the passage 5a formed in the case 5. A second concave portion 2b is formed on one side of the lower surface of the acceleration sensor 1. Second recess 2
In b, passages 2c and 2d communicating with the first and second ventilation holes 10a and 10b are formed. The second concave portion 2b is sealed from the outside by the stopper 11. Therefore, the space A formed by hollowing communicates with the space B above the silicone gel 8 via the first ventilation hole 10a, the concave portion 2b, the second ventilation hole 10b, and the passage 5a. In addition, the first
The second recesses 2a and 2b and the passages 2c and 2d are formed by a mold when the IC 4 is sealed with the sealing resin material 2.

The acceleration sensor 1 thus formed is
As shown in FIG. 3, it is used by being mounted on a printed circuit board 13 together with other circuit elements 12 such as ICs, resistors, and capacitors.

Next, the operation of the acceleration sensor 1 configured as described above will be described. When acceleration is applied to the acceleration sensor 1, the pressure-sensitive element 6 immediately receives pressure via the silicone gel 8. Then, the thin portion 6a of the pressure-sensitive element 6 bends and vibrates relative to the magnitude of the received pressure. At this time, the hollowed space A of the pressure-sensitive element 6 includes the first ventilation hole 10a, the second concave portion 2b, and the second ventilation hole 1a.
Ob and the passage 5a communicate with the space B above the silicone gel 8, so that even if the volume of the hollowed-out space A changes due to the bending and vibration of the thin portion 6a, the increase and decrease are reversed. Since the space B above the silicone gel 8 increases and decreases, the thin portion 6a bends and vibrates without being suppressed. The diffusion strain gauge 6b senses the bending and vibration of the thin portion 6a, and detects the distortion due to the bending and vibration (ie,
An electric signal corresponding to the acceleration is output as a detection signal.

The acceleration detection signal is transmitted to the IC 4 via the bonding wire 7 and the lead 3. The detection signal is amplified by the IC 4 before the lead pin 3b
Are output to various circuit elements 12 on the substrate 13 through
Various processes are performed.

Next, the features of the present embodiment configured as described above will be described below. (1) In the present embodiment, the hollow space A of the pressure-sensitive element 6 is located above the silicone gel 8 via the first ventilation hole 10a, the second concave portion 2b, the second ventilation hole 10b, and the passage 5a. Therefore, even if the volume of the hollowed-out space A changes due to the bending and vibration of the thin portion 6a, the space B above the silicone gel 8 increases and decreases. I do. Therefore, the thin portion 6a can bend and vibrate without being restrained in the vertical direction.
Can detect acceleration.

(2) In the present embodiment, the first vent 1
0a, second concave portion 2b, second vent hole 10b and passage 5
The path consisting of a is a closed structure that is isolated from the outside. As a result, the printed circuit board 1 together with the other circuit elements 12
3 and a coating agent can be applied together, so that an efficient mounting operation can be performed.

(3) In this embodiment, the path has a closed structure isolated from the outside. Therefore, the acceleration sensor 1
Has a completely closed structure and can completely prevent dust from entering the silicone gel 8, so that the mass and viscosity of the silicone gel 8 are kept constant, and the life of the acceleration sensor 1 can be extended.

(4) In the present embodiment, the case 5 has a cylindrical shape with a part of its wall bulging, and a passage 5a is formed in a part of the bulging wall. Accordingly, the space B side above the silicone gel 8 and the hollowed space A
There is no need to provide another member for communicating with the side.
Further, the manufacturing process can be simplified.

The present invention is not limited to the above embodiment, but may be implemented as follows. (1) In the present embodiment, the acceleration sensor 1 is formed by mounting and fixing the case 5 and the pressure-sensitive element 6 on the bottom surface of the first concave portion 2 a of the sealing resin material 2. The case 5 and the pressure-sensitive element 6 are mounted and fixed, and ventilation holes are formed through the alumina substrate at positions corresponding to the hollowed space A of the pressure-sensitive element 6 and positions corresponding to the lower part of the passage 5a. The two ventilation holes may be embodied as a configuration in which the ventilation holes communicate with each other, for example, by a pipe or the like.

(2) In this embodiment, the pressure-sensitive element 6
The hollowed-out space A was communicated with the space B above the silicone gel 8 through the first ventilation hole 10a, the second concave portion 2b, the ventilation hole 10b, and the passage 5a. The space A may be configured in any manner as long as it can communicate with the space B above the silicone gel 8.
For example, they may be connected by a pipe or the like.

(3) In the present embodiment, an integrated circuit device (IC) 4 constituting an amplifier circuit for amplifying a detection signal is adhered on the die pad portion of the lead 3, but the IC 4 is eliminated. In this configuration, the detection signal output from the diffusion strain gauge 6b is not amplified and the lead pins 3b are not amplified.
May be output.

(4) In this embodiment, the cylindrical case 5 is inserted and fixed in the first concave portion 2 a of the sealing resin material 2. It may be integrally formed by itself. In this case, the mold used for sealing the IC 4 needs to be a mold in which the shape corresponding to the case 5 of the above embodiment is formed by the sealing resin material 2.

Next, technical ideas other than the claims that can be grasped from the embodiment will be described below together with the effects. (1) In the acceleration sensor according to claim 2, the communication holes (2b, 2c, 2d) form a second recess (2b) in the sealing resin material (2), and the second recess (2b) is formed in the recess (2b). On the other hand, an acceleration sensor characterized in that it is sealed by providing a plug (11). Thereby, the second concave portion (2
The communication holes (2b, 2c, 2d) having a closed structure can be easily formed simply by plugging the plug (11) with respect to b).

[0031]

As described above in detail, according to the first aspect of the present invention, the acceleration sensor can be mounted on a printed circuit board together with other circuit elements, and a coating agent can be applied at the same time. Has excellent effects that can be performed.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, there is an excellent effect that the ventilation means of a closed structure can be formed without providing another member.
According to the third aspect of the invention, in addition to the effects of the first and second aspects of the invention, there is an excellent effect that the signal detected by the pressure-sensitive element can be amplified and output by the integrated circuit device.

[Brief description of the drawings]

FIG. 1 is a sectional side view of a main part showing an acceleration sensor according to the present embodiment.

FIG. 2 is a plan view showing the acceleration sensor according to the embodiment.

FIG. 3 is an essential part cross-sectional view for describing the acceleration sensor according to the present embodiment.

FIG. 4 is a cross-sectional view of a main part for describing an acceleration sensor according to the related art.

[Description of References] 2 ... sealing resin material, 3 ... lead, 5 ... case, 6 ... pressure sensitive element, 8 ... silicone gel, 2a ... first recess, 2b ... second recess, 2c, 2d ... passage 5a: passage, 6a: thin portion, 10a: first ventilation hole, 10b: second ventilation hole, A
... first space, B ... second space.

Claims (3)

[Claims] 1. A thin portion (6a) is formed with an acceleration transmitting medium (8) housed in a case (5), one surface of which is covered with the acceleration transmitting medium (8) and the other surface is a first surface. Is formed, and the thin portion (6a) bends and vibrates in the acceleration transmission medium (8) that bends and vibrates based on an externally applied acceleration. An acceleration sensor including an element (6), wherein the first space (A) and the case (5) are isolated from the outside air.
Ventilation means (10a, 2b, 2c, 2d, 1) for communicating with the second space (B) above the acceleration transmission medium (8) in the inside.
0b, 5a). 2. The acceleration sensor according to claim 1, wherein said pressure-sensitive element is fixed on a lead.
A recess (2a) is formed in the sealing resin material (2) for sealing the lead (3), and the lead (3) of the recess (2a) is formed.
The case (5) is mounted and fixed thereon, and the ventilation means (10a, 2b, 2c, 2d, 10b, 5)
a) extends vertically in the side wall of the case (5) and communicates with the second space (B) at an upper portion thereof.
And a first ventilation hole (10a) leading from the first space (A) to a lower portion of the lead (3) in the sealing resin material (2).
And a second ventilation hole (10b) extending from the lower part of the passage (5a) of the case (5) to the lower part of the lead (3) in the sealing resin material (2); ), A communication hole (2b, 2c, 2d) for communicating the first ventilation hole (10a) and the second ventilation hole (10b). 3. The acceleration sensor according to claim 2, wherein a detection signal of an acceleration detected by the pressure-sensitive element (6) is provided on a lead (3) sealed with the sealing resin material (2). An acceleration sensor, comprising an integrated circuit device (4) for amplifying the acceleration.