JP3081179B2 - Pressure sensor and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor for detecting a pressure of a fluid, and more particularly to a pressure sensor for receiving a fluid pressure by a semiconductor element and electrically detecting the pressure, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a semiconductor type pressure sensor has been provided as a small pressure sensor capable of accurately measuring the pressure of a fluid. In this semiconductor type pressure sensor, as shown in a longitudinal sectional view of FIG. 5, a sensor element 3 is fixed to a metal main body 1 via a glass pedestal 2. The main body 1 is covered with a cover 4, and the inside of the cover 4 is open to atmospheric pressure.
A through hole 5 is formed in a mounting portion of the sensor element 3 of the main body 1, and a pressure introducing cylinder 6 is mounted in the through hole 5.
The sensor element 3 and the glass pedestal 2 are joined in an airtight state by anodic bonding, and the glass pedestal 2 and the main body 1 are sealed by soldering. Therefore, the pressure introduced from the pressure introducing cylinder 6 is applied to the sensor element 3 so that the pressure is not released to the atmospheric pressure. Further, the electrode portion of the sensor element 3 and the terminal 7 attached to the main body 1 are wire-bonded by a gold wire 8.

In this method of measuring a semiconductor pressure sensor, first, when a measured pressure is applied from the pressure introducing cylinder 6, a physical distortion occurs in the sensor element 3 due to a difference between the atmospheric pressure and the measured pressure. This distortion is proportional to the difference between the measured pressure and the atmospheric pressure. Then, when distortion occurs on the pressure detection surface of the sensor element 3, the value of the resistance formed on the sensor element 3 changes in proportion to the magnitude of the distortion. By detecting the change in the resistance value, amplifying and outputting the amplified value, the pressure difference between the measured pressure and the atmospheric pressure can be measured.

Further, Japanese Patent Application Laid-Open No. 4-155 by the present applicant
As disclosed in Japanese Patent Publication No. 970, a pressure sensor in which a lead frame terminal is insert-molded in a resin case in a semiconductor pressure sensor and a sensor element is fixed to a base end of the terminal in the case has been proposed. In this case, the sensor element is air-tightly fixed to the connection piece connected to the base end of the terminal.

[0005]

However, in the former case, the sensor element 3 is brought into close contact with the glass pedestal 2, and the glass pedestal 2 and the main body 1 are soldered. The cost of parts is also high. Furthermore, there are many joints between the sensor element and other members, and the introduced pressure is likely to leak to the atmosphere side, so that accurate measurement cannot be performed or toxic gas may leak to the outside. Also, in the latter case of the above conventional technology,
There is no airtightness between the connection piece and the resin of the insert-molded lead frame, and the measured pressure leaks from between the connection piece and the resin, causing the same problem as described above.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has a sensor having a high airtightness, a pressure medium to be measured which is safe without leaking to the outside, and a simple structure. It is an object of the present invention to provide a manufacturing method thereof.

[0007]

SUMMARY OF THE INVENTION The present invention provides a semiconductor pressure sensor element and a metal tube having a coefficient of thermal expansion close to the coefficient of thermal expansion of the sensor element and having a flange at a base end thereof.
And has a pressure introduction for introducing the measurement pressure, together with a resin sensor case for accommodating the sensor element, and insert molding the flange portion of the pressure introducing tube, the sensor
The base section of the flange exposed in the case
Sensor element and a silicon-based element around the sensor element.
Adhesive is applied to the sensor element and the pressure introducing cylinder.
It is a pressure sensor characterized by being joined in an airtight state .

[0008] The present invention, the proximal end portion to introduce the measuring pressure
A pressure introducing cylinder having a flange portion, a lead frame having a lead frame terminal to which a plurality of sensor elements are respectively connected, a plurality of resin sensor cases accommodating the sensor elements, and a plurality of the pressure introducing cylinders The above-mentioned flange portion is insert-molded integrally with the lead frame,
Base end face of the flange portion exposed in the sensor case
The sensor element is brought into contact with the
The sensor element and the pressure
A method of manufacturing a pressure sensor, comprising joining an introduction cylinder in an airtight state, and thereafter separating the lead frame terminal for each sensor element.

In the pressure sensor according to the present invention, since the sensor element is directly adhered to the pressure introducing cylinder, the pressure medium to be measured directly penetrates into the back surface of the semiconductor pressure sensor element via the pressure introducing cylinder, and the pressure is reduced. The measured pressure is not applied to components other than the pressure introducing cylinder and the sensor element of the sensor.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The pressure sensor according to this embodiment includes:
A sensor element 20 of a Si semiconductor is provided in a sensor case 21, and the sensor element 20 and a base end 22 a of a lead frame terminal 22 are wire-bonded by a gold wire 23. The sensor case 21 is a heat-resistant resin such as PPS resin, and the lead frame terminal 22 and the pressure introducing cylinder 25 are integrally provided by insert molding.

The pressure introducing cylinder 25 is an iron-nickel alloy having a coefficient of thermal expansion close to that of silicon (3.2 × 10 −6), and may further contain chromium, aluminum or copper. . The pressure introducing cylinder 25 is a cylindrical tube formed by forging, and a flange 26 for mounting a sensor is formed at a base end, and an adhesive 27 for bonding silicon or metal is used. Are bonded in an airtight state. The pressure introducing cylinder 25 is formed to protrude downward from the center of the sensor case 21.

The method for manufacturing the pressure sensor according to this embodiment is as follows.
First, the lead frame 30 shown in FIG. 4 is formed, and the base end 22a of each lead frame terminal 22 of the lead frame 30 and the flange portion 26 of the pressure introducing cylinder 25 are installed so as to face each other, and the lead frame 30 is surrounded. And the sensor case 21
Is insert molded. At this time, the end surface of the flange portion 26 is formed in a rectangular shape and has an exposed portion not covered with the resin, and the surface of the base end portion 22a of the lead frame terminal 22 is also exposed so as not to be covered with the resin. Then, the flange portion 26 of the pressure introducing cylinder 25 located inside the sensor case 21
Then, the sensor element 20 is adhered with an adhesive 27 to seal the periphery of the sensor element 20 so that gas does not leak between the front and back of the sensor element 20. Then, between the base end portion 22a of the lead frame terminal 22 and the electrode of the sensor element 20,
Wire bonding is performed with the gold wire 23. Further, a resin coating or the like is applied to the surface side of the sensor element 20, and the lead frame terminal 22 is bent and formed into a predetermined shape, and the assembly of the pressure sensor of this embodiment is completed.

Here, a large number of such pressure sensors are formed on the lead frame 30 at the same time and then attached to individual substrates. Therefore, even if the lead frame terminals 22 are cut off from the holding portions 32 on both sides of the lead frame 30, the sensor case 21 and the pressure introducing cylinder 25 do not fall off from the holding portions 32 of the lead frame 30. The holding piece 34 that is insert-molded with the case is formed on all sides. The holding piece 34 is connected to the holding portion 32 and is connected to the lead frame terminal 2.
2 is cut and formed into a predetermined shape, and then cut when the pressure sensor is incorporated into a substrate.

In the pressure sensor configured as described above, as shown in FIG.
And is electrically connected to an external connection terminal 42 attached to the substrate 40. Here, in FIG. 3, the right side of the center line is a vertical section in the extension direction of the lead frame terminal 22, and the left side of the center line is a vertical section in a direction orthogonal to the extension direction of the lead frame terminal 22. The sensor case 21 to which the substrate 40 is fixed is attached to the outer case main body 41, and the pressure introducing cylinder 25 is fitted into the mounting portion 44 of the outer case main body 41. Mounting part 44
Is formed integrally with the outer case main body 41 and coaxially communicates with a pressure introducing portion 45 to which the pressure medium to be measured is guided. The outer case body 41 is formed of a resin having excellent chemical resistance and corrosion resistance such as PPS resin. And
An O-ring 46 is tightly fitted between the outer surface of the pressure introducing tube 25 fitted into the mounting portion 44 and the inner wall surface of the mounting portion 44. The O-ring 46 has a pressure introducing cylinder 2 on both sides.
5 and the mounting portion 44 are elastically pressed in an airtight state, do not contact the lower surface of the mounting portion 44, and do not contact the stopper plate 47 fixed to the upper surface of the mounting portion 44. Fixed.

In the sensor case 21, the surface of the sensor element 20 is filled with a filler such as a flexible polyurethane gel or silicone gel, and the sensor element 20 and the like are completely sealed. Further, a lid member 48 is attached to the outer case main body 41. The opening of the sensor case 21 fits into the mounting portion 50 formed on the inner surface of the lid member 48 to securely hold the sensor case 21 and prevent the pressure introducing cylinder 25 from falling out of the mounting portion 44. keeping. An atmospheric pressure inlet 49 connected to the atmospheric pressure side is formed in the lid member 48 so that the atmospheric pressure is reliably applied to the front side of the sensor element 20.

The method of using the pressure sensor of this embodiment is as follows.
The pressure introducing section 45 is connected to the measured pressure side, and the atmospheric pressure introducing port 49 is opened to the atmospheric pressure side. The pressure medium to be measured can be used, for example, as a combustible gas such as LP gas, other toxic gas, high-pressure gas, or the like.

According to the pressure sensor of this embodiment, the gas or the like whose pressure is to be measured passes through the pressure introducing section 45, directly contacts the back side of the sensor element 20 via the pressure introducing cylinder 25, and the pressure is directly applied to the sensor element 20. Such is the case. Accordingly, the sensitivity is extremely high, the apparatus can be downsized, and extremely accurate measurement can be performed even when detecting a low pressure. Further, the sensor element 20 is provided with a pressure introducing cylinder 25 having a thermal expansion coefficient close to this.
Therefore, stress due to thermal strain is hardly transmitted to the sensor element 20, and the airtightness is extremely high and the reliability is high. In particular,
An adhesive 27 is adhered around the sensor element 20 so that the sensor element
Since the armature 20 and the pressure introducing cylinder 25 are joined, airtightness is improved.
The coefficient of thermal expansion between the sensor element 20 and the pressure introducing cylinder 25 is high.
Absorbs misalignment due to slight differences, and breaks airtightness
I try not to. Further, the franc of the pressure introducing cylinder 25
The insert part is insert-molded in the sensor case 21
The airtightness between the pressure introducing cylinder 25 and the sensor case 21
And the strength is extremely high.
The input cylinder 25 and the sensor case 21 do not come off, and
Since the joint area between them is large, some airtightness can be secured.
Wear. Further, it has high durability against corrosive gas and the like. Also, in the sensor device of the outer case main body 41 incorporating the pressure sensor, the gas for measuring the pressure contacts only the pressure introducing part 45, the O-ring 46, the pressure introducing cylinder 25, and the sensor element 20, Without touching other components or joints, each of the above members can be selected to have extremely high reliability against corrosion, durability and the like. Therefore, sufficient safety can be ensured even when measuring a toxic gas or a flammable gas.

The pressure sensor according to the present invention is not limited to the above-described embodiment, and the joining method between the sensor element and the pressure introducing cylinder may be a joining method other than the adhesive. Further, the sensor element may be joined to the pressure introducing cylinder before insert molding. The material of the pressure introducing cylinder can be changed as appropriate, and may be any material as long as it is close to the coefficient of thermal expansion of the sensor element.

[0019]

According to the pressure sensor of the present invention, since the above-mentioned sensor element and the pressure introducing cylinder are directly joined to each other, the reliability for airtightness can be made extremely high. Furthermore, in this pressure sensor, since the sensor element was attached to the pressure introducing cylinder having a coefficient of thermal expansion close to that of the sensor element,
Accurate measurement is possible without transmitting thermal strain to the sensor element. Also, the pressure sensor can be easily manufactured by insert molding, the sensor element and the pressure introducing cylinder can be easily joined, and the manufacturing cost can be reduced. Further, the pressure sensor can be reduced in size and can be efficiently assembled. And the flange of the pressure introducing cylinder is the sensor case
Since it is insert-molded on the pressure introduction cylinder and sensor
The airtightness and strength between the case and the case are extremely high. In addition,
The sensor element is bonded to the pressure introducing cylinder with a silicone-based adhesive.
Absorbs thermal displacement and contraction due to contraction,
Airtightness is reliably maintained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a pressure sensor according to an embodiment of the present invention.

FIG. 2 is a plan view of the pressure sensor according to the embodiment.

FIG. 3 is a longitudinal sectional view showing a state in which the pressure sensor of this embodiment is attached to an outer case.

FIG. 4 is a plan view of a lead frame used for the pressure sensor of the embodiment.

FIG. 5 is a longitudinal sectional view of a conventional pressure sensor.

[Explanation of symbols]

 Reference Signs List 20 sensor element 21 sensor case 22 lead frame terminal 25 pressure introducing cylinder

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-155970 (JP, A) JP-A-3-37536 (JP, A) JP-A-4-69535 (JP, A) JP-A-63- 238535 (JP, A) Hikaru 2-144744 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01L 9/04 101 H01L 29/84

Claims (2)

(57) [Claims] 1. A pressure sensor element comprising a semiconductor pressure sensor element and a metal pipe having a coefficient of thermal expansion close to the coefficient of thermal expansion of the sensor element and having a flange at a base end thereof for introducing a pressure to be measured. And the like, and the flange portion of the pressure introducing cylinder is insert-molded integrally with the resin-made sensor case for housing the sensor element, and is exposed in the sensor case
The sensor element is brought into contact with the base end face of the flange,
Apply a silicone adhesive around the sensor element to
A pressure sensor wherein the sensor element and the pressure introducing cylinder are joined in an airtight state . 2. A pressure-measured pressure is introduced, and a flange portion is provided at a base end portion.
And a lead frame having a lead frame terminal to which a plurality of sensor elements are respectively connected, a plurality of resin sensor cases accommodating the sensor elements, and the plurality of flanges of the plurality of pressure introduction cylinders a part integrally insert molded with the lead frame, the Sensake
The sensor is mounted on the base end face of the flange exposed in the base.
Contact the element and bond silicon based around the sensor element
A method for manufacturing a pressure sensor, comprising: adhering an agent, joining the sensor element and the pressure introducing cylinder in an airtight state, and thereafter separating the lead frame terminal for each sensor element. .