JP2004309329A - Pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify the component constitution, while keeping a function for preventing a an adverse influence when an electric potential is generated between a device frame earth and a secondary power source. <P>SOLUTION: In a pressure detection element 10, a hermetic glass 13 is hermetically fixed on a center aperture 12 of a metal element housing 11. In the hermetic glass 13, a lead pin 14 for leading an electric signal from a sensor chip 18 to the outside, a conductive member fixing lead pin 14-2, and a sensor chip mounting glass member 16 for holding the sensor chip 18 are provided. The conductive member 1 welded on the lead pin 14-2 is arranged between a metal diaphragm 20 and the sensor chip 18, and the lead pin 14-2 is electrically connected to a lead pin 14-1 connected to the zero electric potential of an electronic circuit loaded on the sensor chip 18 by a wiring pattern 2 on a substrate 35 for external output. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid-ring type one-chip semiconductor pressure sensor.
[0002]
[Prior art]
Pressure sensors include refrigerant pressure sensors for refrigeration, refrigeration, and air conditioning equipment, water pressure sensors for water supply and industrial pumps, steam pressure sensors for steam boilers, air / hydraulic sensors for air / hydraulic industrial equipment, pressure sensors for automobiles, etc. Is used for various purposes.
As such a pressure sensor for detecting a fluid pressure, a diaphragm is separated from a non-measurement fluid area by a diaphragm, and pressure detection of a piezoresistive element or the like is performed in a sealed chamber (liquid sealing chamber) in which an incompressible fluid such as oil is sealed. 2. Description of the Related Art A liquid ring type pressure sensor in which an element is arranged and a fluid pressure of a non-measuring fluid acting on a diaphragm is transmitted to a pressure detecting element via an incompressible fluid in a liquid ring chamber is known (Patent Document 1). ).
In recent years, with the advance of semiconductor technology, a one-chip semiconductor pressure sensor in which a pressure detecting element and a signal processing circuit are integrated on the same silicon chip has been developed.
[0003]
FIGS. 2A and 2B are diagrams showing the configuration of such a conventional liquid-ring type one-chip semiconductor pressure sensor, wherein FIG. 2A is a cross-sectional view showing the configuration of a liquid-ring type one-chip semiconductor pressure sensor, and FIG. It is sectional drawing which expands and shows the part of a chip.
As shown in this figure, the liquid ring type pressure sensor is roughly composed of a pressure detecting element 10, a joint part 30, and a connector part 40.
The pressure detecting element 10 includes a metal element housing 11, a hermetic glass 13 fixed hermetically to a central opening 12 of the element housing 11, a plurality of lead pins 14 hermetically mounted through the hermetic glass 13, and an oil. It comprises a filling pipe 15, a sensor chip mounting member 16, and a pressure detecting sensor chip 18 fixed to the upper end surface of the sensor chip mounting member 16 via a glass 17.
As shown in FIG. 2B in an enlarged manner, the sensor chip 18 has a diaphragm (silicon diaphragm) formed by etching the center of the back surface of the silicon substrate, and a bridge circuit is provided above the silicon diaphragm. A plurality of pressure detecting elements (piezoresistive elements) 18-1 to be formed are formed, and electronic circuits such as an amplifier circuit for processing an output signal of the bridge circuit, a linear correction circuit, a temperature correction circuit, and a correction data holding circuit are formed therearound. 18-2 is integrated by a semiconductor circuit integration technique, and an oxide film 18-3 is formed on the surface side. The pressure detection sensor chip 18 and the lead pin 14 are connected by a wire (not shown) or the like.
[0004]
Further, a metal diaphragm 20 and a diaphragm protection cover 22 having a communication hole 21 covering the metal diaphragm 20 are hermetically sealed at the upper opening edge of the central opening 12 of the element housing 11 by welding their outer peripheral edges. It is fixed to. The central opening 12 of the element housing 11, the hermetic glass 13, and the metal diaphragm 20 form a liquid sealing chamber 23 in which oil such as silicon oil is sealed.
For example, the oil filling pipe 15 made of stainless steel is used as a filling port for filling the liquid sealing chamber 23 with oil, and after the oil filling is completed, the tip of the outer pipe is crushed and brought into close contact, and the portion is welded. Thus, the oil is sealed in the liquid sealing chamber 23.
[0005]
The pressure detecting element 10 is fitted into the element housing hole 31 of the joint 30 together with the O-ring 24. Further, the connector portion 40 is fitted together with the O-ring 25 into the element housing hole 31 of the joint portion 30, and the opening edge 32 of the element housing hole 31 is swaged, so that the joint portion 30 sandwiches the pressure detecting element 10. And fixedly connected.
[0006]
The joint portion 30 is attached to the portion to be measured by the screw portion 33 for sensor attachment, and the pressure of the fluid is transmitted to the metal diaphragm 20 via the fluid pressure passage 34 to be measured. Since the metal diaphragm 20 is extremely thin, the pressure is transmitted to the oil without lowering the pressure. The silicon diaphragm of the sensor chip 18 is deformed by this pressure, and an electric signal detected by the piezoresistive element 18-1 is converted into an electric signal by the electronic circuit 18. -2 and output to the lead pin 14. An external output board 35 such as a flexible printed circuit board (FPC) for electrically connecting the lead pins 14 to the terminals 41 of the connector section 40 is provided. An electric signal from the sensor chip 18 is transmitted through the lead pins 14 and the terminals 41. To be taken out.
A plurality of lead pins connected to a power supply potential, a zero potential, an output terminal, and one or more test points of the sensor chip 18 are provided as the lead pins 14. And three terminals of a power supply terminal, a ground terminal, and an output terminal which are respectively connected to the power supply potential, the zero potential, and the output terminal.
[0007]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-35850
[Problems to be solved by the invention]
When such a one-chip semiconductor pressure sensor is used, a secondary voltage (for example, DC 5V) of a device to which the pressure sensor is attached is supplied to an electronic circuit on the sensor chip 18 and the element housing 11 The frame ground of the device is connected. Here, the electronic circuit on the sensor chip 18 and the element housing 11 are in a highly insulated state. Although the secondary power supply is insulated from the primary power supply by a transformer or the like, since the impedance of the sensor is higher, a potential is generated between the metal diaphragm 20 welded to the element housing 11 and the sensor chip 18. This may adversely affect the electronic circuits in the sensor chip 18, the nonvolatile memory, and the like.
[0009]
In view of this, the present applicant has proposed a pressure sensor capable of preventing the occurrence of an adverse effect even when a potential is generated between the apparatus frame ground and the secondary power supply (Japanese Patent Application No. 2002). -192207).
FIG. 3 is a diagram showing one form of the pressure detecting element 10 in the pressure sensor proposed by the present applicant. The same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. Further, the sensor chip 18 is simply shown, and the glass 17 is not shown.
As shown in this figure, in the pressure detecting element 10, the height of the outer peripheral portion of the hermetic glass 13 is formed higher than the center portion, and a ring-shaped metal member 51 is fitted inside the outer peripheral portion. I am trying. Then, a hole for inserting the lead pin 14-1 connected to the zero potential of the electronic circuit is made in the metal member 51, and the lead pin 14-1 is inserted into the hole, and the metal member 51 is crushed and crimped. Thus, the metal member 51 and the lead pin 14-1 are mechanically and electrically connected. A metal plate 52 is electrically and mechanically connected to the upper surface of the metal member 51 by welding. The metal plate 52 has an opening 53.
[0010]
Thereby, between the sensor chip 18 and the metal diaphragm 20, the metal plate 52 and the metal member 51 which are set to the same potential as the zero potential of the electronic circuit integrated on the sensor chip 18 can be arranged. Even when there is a potential difference between the metal diaphragm 20 and the zero potential of the electronic circuit on the sensor chip 18, a potential difference exists between the zero potential of the electronic circuit on the sensor chip 18 and the metal plate 52. Since this does not occur, an adverse effect on the electronic circuit integrated on the sensor chip 18 can be prevented.
[0011]
However, in the configuration shown in FIG. 3, since a part obtained by caulking the metal member 51 and the lead pin 14-1 for zero potential is subjected to glass hermetic processing, the structure becomes complicated, and it is very difficult to manufacture the glass hermetic. There was a problem that it was difficult.
In the caulking process of caulking and connecting the lead pin 14-1 and the metal member 51, very small parts are handled, so that there is a problem in management of the mold.
[0012]
Therefore, the present invention provides a pressure sensor with a simplified component configuration while maintaining the function of preventing the occurrence of adverse effects even when a potential is generated between the apparatus frame ground and the secondary power supply. It is intended to be.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a pressure sensor according to the present invention includes a metal housing, a sensor chip mount member fixed to a central opening provided in the metal housing, and supporting a pressure sensor chip, Liquid seal including a pressure detection element having a hermetic glass provided with a lead pin for leading out an electric signal from the pressure pipe and the pressure sensor chip to the outside, and a metal diaphragm bonded to one end surface of the housing. Type pressure sensor, a conductive member disposed between the pressure sensor chip and the metal diaphragm, and a conductive member provided on the hermetic glass and electrically and mechanically connected to the conductive member. Conductive member supporting pin, the conductive member supporting pin and the zero voltage of an electronic circuit mounted on the pressure sensor chip. And it has a means for electrically connecting connected a lead pin.
Means for electrically connecting the conductive member support pin and a lead pin connected to zero potential of an electronic circuit mounted on the pressure sensor chip derives an electric signal from the pressure sensor chip to the outside. Wiring patterns provided on an external output substrate for connecting lead pins and output terminals.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram showing a configuration of a pressure detecting element 10 according to an embodiment of the pressure sensor of the present invention. FIG. 1A is a cross-sectional view showing the configuration of the pressure detecting element 10, and FIG. FIG. 3A is a diagram showing a state in which an external output board 35 such as a flexible printed circuit board (FPC) connected to terminals of the pressure detecting element is viewed from below in FIG. In this figure, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals, and description thereof will be omitted.
[0015]
In FIG. 1A, reference numeral 1 denotes a conductive member disposed between the metal diaphragm 20 and the sensor chip 18. The conductive member 1 may have an arbitrary shape such as a disk shape. In this embodiment, as shown in the figure, the peripheral portion is directed downward (in the direction of the sensor chip 18) in the figure. It has a bent shape. With such a shape, the periphery of the sensor chip 18 can be surrounded.
Reference numeral 14-2 denotes at least three or more conductive member fixing lead pins provided to support the conductive member 1, and other lead pins 14, an oil filling pipe 15, and a sensor chip mounting member 16 are provided. Like the above, it is hermetically mounted on the hermetic glass 13 in a penetrating state. The conductive member fixing lead pin 14-2 is made of metal, and as shown in the drawing, the upper end (the sensor chip 18 side) in the figure is in contact with the conductive member 1, and is subjected to spot welding or the like. It is electrically and mechanically connected to the conductive member 1.
[0016]
In FIG. 1B, an external output board 35 connects the lead pin 14 described with reference to FIG. 2 and the terminal 41 of the connector section 40 (FIG. 2). At least one of the conductive member fixing lead pins 14-2 and a lead pin (zero potential lead pin) 14- of the lead pins 14 connected to a zero potential of an electronic circuit on the sensor chip 18 are connected. 1 is provided. The lead pin 14-1 for zero potential and the lead pin 14-1 for fixing the conductive member are soldered or laser spot-welded to the wiring pattern 2 or the like. 14-2 can be electrically connected.
Thus, the conductive member 1 is set to the same potential as the zero potential of the electronic circuit on the sensor chip 18 by the lead pin 14-1 for zero potential, the wiring pattern 2, and the lead pin 14-2 for fixing the conductive member. . Therefore, between the sensor chip 18 and the metal diaphragm 20, the conductive member 1 having the same potential as the zero potential of the electronic circuit integrated on the sensor chip 18 can be disposed. Even when there is a potential difference between 20 and the zero potential of the electronic circuit on the sensor chip 18, it is possible to prevent adverse effects on the electronic circuits integrated on the sensor chip 18.
[0017]
When manufacturing such a pressure detecting element 10, the conductive member fixing lead pins 14-2 (for example, three) are combined with other lead pins 14 and 14-1, an oil filling pipe 15 and a sensor chip mounting member 16. After inserting into the hermetic glass 13 and performing glass hermetic processing, the sensor chip 18 is fixed to the upper end surface of the sensor chip mounting member 16 and wire bonding is performed. Thereafter, the conductive member 1 and the conductive member fixing lead pin 14-2 are integrated by spot welding or the like. At this time, as can be seen by comparing the shape of the hermetic glass 13 in FIG. 3 with the shape of the hermetic glass 13 in FIG. 1, since the shape of the glass portion is simple, the reliability of the glass hermetic is eliminated, for example, micro cracks are eliminated. And the flowability of glass are improved, and the yield of non-defective parts can be greatly improved.
[0018]
Thus, in the pressure sensor of the present invention, the conductive member fixing lead pins (three) 14-2 are used instead of the metal members 51 in the configuration shown in FIG. 2 and the conductive member 1 are welded to make a mechanical and electrical connection, and the electrical connection between the zero potential lead pin 14-1 and the conductive member fixing lead pin 14-2 is made in a pattern such as the external output board 35. By performing the connection, the same function as in the case of FIG. 3 is performed.
Therefore, the caulking step can be omitted, and the cost of parts and the number of man-hours for manufacturing parts can be reduced.
[0019]
The shape of the conductive member 1 is not limited to the shape shown in FIG. 1, but may be an arbitrary shape such as a disk shape.
In the above-described embodiment, the conductive member fixing lead pin 14-2 and the conductive member 1 are electrically and mechanically connected by welding. However, a conductive adhesive is used. For example, other connection methods may be adopted.
Further, the material of the conductive member 1 is not limited to metal, but may be a conductive resin or the like as long as it can be electrically and mechanically connected to the conductive member fixing lead pin 14-2. Can be used.
Furthermore, in the above-described embodiment, the external output substrate is used to electrically connect the zero potential lead pin 14-1 and at least one of the conductive member fixing lead pins 14-2. Although the wiring pattern 2 provided on the 35 is used, the present invention is not limited to this, and a conductive component that engages with both the zero potential lead pin 14-1 and the conductive member fixing lead pin 14-2. May be inserted or fitted.
[0020]
【The invention's effect】
As described above, according to the pressure sensor of the present invention, the sensor chip can be placed in no electric field (zero potential), and the circuit in the chip is affected by the potential generated between the device frame ground and the secondary power supply. And the non-volatile memory and the like can be prevented from being adversely affected.
Since the conductive member fixing lead pin 14-2 is provided instead of the metal member 51 and the electrical connection with the conductive member 1 is performed by the external output board 35 or the like, the caulking step is omitted. Effects such as reduction in parts cost and man-hours for manufacturing parts can be achieved.
Further, the reliability of the glass hermetic and the flowability of the glass can be improved, and the non-defective product rate can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a pressure detecting element in an embodiment of a pressure sensor according to the present invention, wherein (a) is a cross-sectional view of the pressure detecting element, and (b) is a pressure detecting element and the pressure detecting element. It is a figure which shows the mode which looked at the board | substrate for external output which consists of a flexible printed circuit board (FPC) etc. connected to a terminal from FIG.
FIGS. 2A and 2B are diagrams showing a conventional liquid-ring type one-chip semiconductor pressure sensor, in which FIG. 2A is a cross-sectional view showing the configuration of a liquid-ring type one-chip semiconductor pressure sensor, and FIG. FIG.
FIG. 3 is a cross-sectional view showing one configuration example of a pressure detecting element in the proposed pressure sensor.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 conductive member 2 wiring pattern 10 pressure detecting element 11 element housing 12 central opening 13 hermetic glass 14 lead pin 14-1 lead pin for zero potential 14-2 lead pin for fixing conductive member 15 oil filling pipe 16 sensor chip mounting member 18 Pressure sensor chip 20 Metal diaphragm 35 External output board

Claims (2)

A metal housing and a sensor chip mounting member fixed to a central opening provided in the metal housing and supporting the pressure sensor chip, an oil filling pipe, and an electric signal from the pressure sensor chip are led out. A liquid ring type pressure sensor including a hermetic glass provided with a lead pin for performing, and a pressure detection element having a metal diaphragm bonded to one end surface of the housing,
A conductive member disposed between the pressure sensor chip and the metal diaphragm,
A conductive member support pin provided on the hermetic glass and electrically and mechanically connected to the conductive member,
Means for electrically connecting the conductive member support pin and a lead pin connected to zero potential of an electronic circuit mounted on the pressure sensor chip. Means for electrically connecting the conductive member support pin and a lead pin connected to a zero potential of an electronic circuit mounted on the pressure sensor chip, for leading an electric signal from the pressure sensor chip to the outside. 2. The pressure sensor according to claim 1, wherein the wiring pattern is a wiring pattern provided on an external output board for connecting the lead pin and the output terminal.

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