JP2001033326A - Pressure detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure detector capable of high pressure measurement of gas, with simple constitution of low cost. SOLUTION: A semiconductor pressure sensor 4 is arranged in an accommodating part 4, and detects the pressure of fluid applied from an aperture part of the accommodating part 4. Lead pins (lead part) 9 are arranged in the vicinity of the sensor 4 of the accommodating part 4. Lead wires 10 connect electrically the lead pins 9 with the sensor 4. A gel type member (first protective member) 11 covers a diaphragm (pressure receiving part) of the sensor 4, and makes it possible to detect the pressure of fluid with the pressure receiving part. Protective member (second protective member) 12 covers a part of the sensor which is not covered with the gel type member 11, lead pins 9 and the connection wires 10, and is harder than the gel type member 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure detector for protecting a semiconductor pressure sensor with a gel member, and more particularly to a pressure detector which can be used for measuring high-pressure gas.

[0002]

2. Description of the Related Art For detecting pressure, a semiconductor type pressure sensor having a thin diaphragm on which a piezoresistive element is formed is often used. A pressure detector using this pressure sensor is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-26483.
There is one disclosed in Japanese Patent Publication No. 0 (JP-A) No.

[0003] This pressure detector will be described with reference to FIG. 2. The pressure detector A is a case body composed of a base plate 1 made of a metal material such as Kovar and a cylindrical portion 2 made of a metal material such as SPC. And a semiconductor pressure chip 6 having a thin film diaphragm on a glass pedestal 5 bonded to the bottom surface of a concave storage portion 4 formed by the base plate 1 and the cylindrical portion 2 by an anodic bonding method. A pressure sensor 7 is provided. In the pressure detector A, an electrode portion (not shown) formed on the surface of the pressure chip 6 in the pressure sensor 7 and a plurality of lead pins 9 fixed to the base plate 1 via a sealing glass 8 by a connection wire 10. The pressure sensor 7, the lead pins 9, and the connection wires 10 are electrically connected and filled in the housing 4 with a gel member 11 made of silicon gel, fluorosilicon gel, or the like.
Is not affected by the pressure medium. Since the pressure detector A has a simple configuration and is inexpensive, it is generally used as a low pressure measurement pressure detector using gas as a pressure medium.

[0004]

In the pressure detector A having such a structure, the gel-like member 11 is filled in the entire accommodating portion 4, and the pressure sensor 7, the lead pins 9 and the connection wires 10 are connected by the gel-like member 11. For example, 1.5MPa (15kg / cm2)
When the high-pressure fluid (particularly gas) is applied to the gel-like member 11, the gel-like member 11 is moved in the shearing direction (downward along the wall) at the interface between the wall of the case body 3 and the gel-like member 11. When the gel member 11 is displaced by being pressed in the direction (direction) and tries to return to the original position due to the reaction that is pressed, the pressure medium is entangled in the gel member 11. Therefore, the pressure detector A having the gel member 11 in which the pressure medium is mixed as described above.
Is used as a pressure detector for measuring high pressure under severe environmental conditions, such as a vehicle, when the characteristics of the pressure sensor 7 change due to thermal expansion of the mixed pressure medium,
Further, there is a possibility that the connection wire 10 may be cut, and the pressure detector A having such a configuration cannot be used for high-pressure measurement of gas, and is generally installed in a housing provided with a pressure sensor. A so-called two-diaphragm pressure detector is used, which is filled with a filling member such as silicone oil and covers the opening of the housing with a thin metal diaphragm. However, since the structure of the double-diaphragm pressure sensor is complicated and expensive, it is desirable to use a simple structure as described above and to enable high-pressure measurement of gas with an inexpensive pressure sensor. It is rare.

The present invention has been made in view of the above problems, and has as its object to enable high pressure measurement of gas with a simple configuration and an inexpensive pressure detector.

[0006]

According to the present invention, there is provided a semiconductor pressure sensor provided on a base plate for detecting a pressure of a fluid, and provided near the semiconductor pressure sensor. A lead portion provided on the base plate, a connection wire for electrically connecting the lead portion and the semiconductor type pressure sensor, and a pressure receiving portion of the semiconductor type pressure sensor. A first protection member that is capable of detecting the pressure of the semiconductor pressure sensor, a portion of the semiconductor pressure sensor that is not covered by the first protection member, the lead portion, and the connection wire. And a second protection member which is harder than the above protection member.

In addition, a semiconductor pressure sensor is provided in the storage section and detects a pressure of a fluid applied from an opening of the storage section, and is provided in the storage section in the vicinity of the semiconductor pressure sensor. A lead portion, a connection wire for electrically connecting the lead portion and the semiconductor type pressure sensor, and a pressure receiving portion of the semiconductor type pressure sensor are covered, and the pressure of the fluid can be detected by the pressure receiving portion. A first protection member that covers the portion of the semiconductor pressure sensor that is not covered by the first protection member, the lead portion, and the connection wire, and a second protection member that is harder than the first protection member. And a protective member.

[0008] The first protective member is made of silicon gel or fluorosilicon gel.

The second protective member is made of silicone rubber or silicone-modified epoxy.

Further, the first protection member is provided so as to protrude from an upper end of the second protection member.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the same or corresponding parts as those in the conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted. still,
The pressure detector described below is used for high pressure measurement of gas.

In FIG. 1, a pressure detector A 'includes a base plate 1 made of a metal material such as Kovar and a case body 3 made up of a cylindrical portion 2 made of a metal material such as SPC. A semiconductor pressure sensor 7 formed by joining a semiconductor pressure chip 6 on a glass pedestal 5 by an anodic bonding method is provided on the bottom surface of a concave storage portion 4 obtained by welding the cylindrical portion 2. .

The pressure detector A 'includes a plurality of lead pins (electrode terminals) 9 made of a conductive material that is electrically connected to each electrode (not shown) formed on the surface of the pressure chip 6 in the pressure sensor 7. Each of the lead pins 9 is fixed around the pressure sensor 7 in the storage section 4 via a sealing glass 8 and is electrically connected to the pressure sensor by a connection wire 10 made of a conductive material such as gold or aluminum.

A feature of the pressure detector A 'of the present invention is that the pressure sensor 7 covers a diaphragm, which is a pressure receiving portion displaced by the gas pressure of the pressure chip 6, and detects the gas pressure by the diaphragm. A gel-like member (first protection member) 11 that enables the above-mentioned operation, and a protection member (second protection member) 12 that covers portions of the pressure sensor 7 other than the diaphragm, the lead pins 9 and the connection wires 10 of the pressure sensor 7. In that it comprises:

That is, in the pressure detector A 'of the present invention, a portion other than the diaphragm of the pressure sensor 7, the lead pin 9, and the connection wire 10 are connected to the gel-like member 11 in the housing portion 4 in which the pressure sensor 7 is provided. The protective member 12 is covered with a harder member, and the diaphragm is covered with a gel-like member 11 whose cured shape protrudes upward from the upper end of the protective member 12. As the material of the gel member 11, silicon gel or fluorosilicon gel is used, and as the material of the protective member 12, silicon rubber or silicone-modified epoxy is used.

When the pressure detector A 'is used as a pressure detector for measuring a high pressure of a gas under severe operating conditions, the protective member 12 is moved in the shearing direction at the interface between the wall of the case body 3 and the protective member 12. Even when pressed (in a downward direction along the wall), there is no displacement, so that the pressure medium is not involved, and the connection wire 10 can be prevented from being cut. Further, since the gel-like member 11 is provided so as to protrude above the protection member 12, the interface between the wall surface of the protection member 12 and the gel-like member 11 does not exist on the surface. Elimination of the pressure medium (for example, air bubbles) is eliminated, and a change in characteristics of the pressure sensor 7 can be prevented. Accordingly, since the above-described effect can be obtained by the above-described pressure detector A ′ with a relatively simple configuration, it is possible to measure the high pressure of gas with an inexpensive pressure detector.

Further, as in the pressure detector A 'shown in the embodiment of the present invention, the gel member 11 is made of silicon gel or fluorosilicon gel, and the protective member 12 is made of silicon rubber or silicone-modified epoxy. Accordingly, the pressure sensor 7 is covered by the gel-like member 11 and the protection member 12 that are close to the thermal expansion coefficient of the pressure sensor 7, and therefore, the distortion caused by the difference in the thermal expansion coefficient between the members can be suppressed. Characteristic changes in the pressure sensor 7 can be suppressed, and accurate pressure detection can be obtained.

Next, a method of manufacturing the above-described pressure detector A 'will be described. In the method of manufacturing the pressure detector A ', after preparing the base plate 1 having the lead pins 9 and disposing the pressure sensor 7 (the glass pedestal 5 in the pressure sensor 7).
A metallized layer is formed on the surface facing the base plate 1 and fixed to the base plate 1 by soldering), and the electrode portions of the pressure sensor 7 and the lead pins 9 are connected by connecting wires 10 (wire bonding). Part 2 to base plate 1
And weld both members.

The storage section 4 in the pressure detector A '
Inside, the protective member 12 is formed using a dedicated jig for separating the diaphragm of the pressure sensor 7 from other portions.
Is filled in the storage portion 4 and the protective member 12 is defoamed, and then the protective member 12 is thermally cured. Next, remove the jig,
The cured gel-like member 1 is placed in a concave portion formed at a position corresponding to the diaphragm by removing the jig.
The gel-like member 11 is filled in such a manner that the shape 1 protrudes upward from the upper end of the protective member 12, and the pressure sensor 7
The above-mentioned diaphragm is covered with a gel-like member 11 and the gel-like member 11 is defoamed and cured (cured by heat or at room temperature) to complete the pressure detector A 'of the present invention.

In the embodiment of the present invention, the base plate 1
The case body 3 forms the housing part 4 for housing the pressure sensor 7 with the cylinder part 2. The present invention constitutes a housing part for housing the pressure sensor 7 with the case body itself having a concave shape. Is also good.

Further, in the embodiment of the present invention, the lead pins 9 are fixed to the base plate 2 of the case body 1 with the glass 8 for sealing. However, the present invention comprises the case body made of a resin material. Alternatively, a lead portion electrically connected to the pressure sensor may be insert-molded in the case body.

In the embodiment of the present invention, the gel member 11 is provided so as to protrude above the upper end of the protective member 12 after curing. If it can be neglected, it is not always necessary to provide the gel-like member in a protruding state, and in this case, the gel-like member is formed such that the gel-like member and the protection member are flat, and the gel-like member is more than the protection member. What is necessary is just to be provided so that it may become one step lower.

Although the embodiment of the present invention has been described as a pressure detector for measuring high pressure of gas, the pressure detector of the present invention can also be used for measuring low pressure of gas or liquid.

Further, in the embodiment of the present invention, the case body 3 is constituted by the base plate 1 and the cylindrical portion 2.
According to the present invention, in the step of forming the protective member 12, for example, a state in which the protective member 12 is exposed by removing the tubular portion 2 after the protective member 12 is cured, that is, a pressure detector without the outer frame is formed only by the base plate 1. In addition, the configuration can be simplified and an inexpensive pressure detector can be obtained.

[0025]

According to the present invention, a first protection member that covers a pressure receiving portion of a semiconductor type pressure sensor and enables the pressure of the fluid to be detected by the pressure receiving portion is provided. The semiconductor pressure sensor has a simple configuration in which the semiconductor pressure sensor is covered with a second protection member harder than the first protection member, while covering a portion of the semiconductor pressure sensor that is not covered, a lead portion, and a connection wire. In addition, the entrainment of the pressure medium at the time of application of the gas high-pressure fluid is eliminated, and it is possible to prevent disconnection of the connection wire that electrically connects the semiconductor type pressure sensor and the lead portion.

Further, since the first protection member is provided so as to protrude from the second protection member, an interface between the wall surface of the second protection member and the first protection member exists on the surface. Therefore, the entrainment of the pressure medium when a high-pressure fluid (especially a gas) is applied is eliminated, and it is possible to prevent a change in the characteristics of the semiconductor pressure sensor.

Further, the first protective member is made of silicon gel or fluorosilicone gel, and the second protective member is made of silicon rubber or silicone-modified epoxy, so that the coefficient of thermal expansion of the semiconductor pressure sensor is approximated. Since the semiconductor pressure sensor is covered by the first and second protection members, it is possible to suppress distortion caused by a difference in thermal expansion coefficient between the members,
A characteristic change in the semiconductor pressure sensor can be suppressed, and accurate pressure detection can be obtained.

Further, since the second protective member is hard, an outer frame such as a case surrounding the protective member is not required, the structure of the pressure detector is further simplified, and an inexpensive pressure detector can be provided. Obtainable.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a pressure detector according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a conventional pressure detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base plate 2 Cylindrical part 3 Case body 4 Storage part 7 Semiconductor type pressure sensor 9 Lead pin (lead part) 10 Connection wire 11 Gel-like member (first protection member) 12 Protection member (second protection member) A 'pressure Detector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F055 AA39 BB20 CC02 DD04 EE13 FF01 FF43 FF49 GG01 GG12 GG25 HH11 4M112 AA01 BA01 CA14 EA14 FA07 GA01

Claims (5)

[Claims] A semiconductor pressure sensor disposed on a base plate for detecting a pressure of a fluid; a lead portion provided near the semiconductor pressure sensor and disposed on the base plate; A connection wire for electrically connecting the pressure sensor and the semiconductor pressure sensor; and a first protection member that covers the pressure receiving portion of the semiconductor pressure sensor and enables the pressure of the fluid to be detected by the pressure receiving portion. And a second protection member that is harder than the first protection member, and covers a portion of the semiconductor pressure sensor that is not covered by the first protection member, the lead portion, and the connection wire. A pressure detector, comprising: 2. A semiconductor pressure sensor disposed in a storage portion for detecting a pressure of a fluid applied from an opening of the storage portion, and is disposed in the storage portion in the vicinity of the semiconductor pressure sensor. A lead portion, a connection wire for electrically connecting the lead portion and the semiconductor type pressure sensor, and a pressure receiving portion of the semiconductor type pressure sensor are covered, and the pressure of the fluid can be detected by the pressure receiving portion. A first protection member that covers the portion of the semiconductor pressure sensor that is not covered by the first protection member, the lead portion, and the connection wire, and a second protection member that is harder than the first protection member.
And a protective member. 3. The pressure detector according to claim 1, wherein the first protection member is made of silicon gel or fluorosilicon gel. 4. The pressure detector according to claim 1, wherein the second protection member is made of silicone rubber or silicone-modified epoxy. 5. The pressure detector according to claim 1, wherein the first protection member is provided so as to protrude from an upper end of the second protection member. .