JP4118729B2 - Pressure sensor - Google Patents

Description

[0001]
BACKGROUND 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. It is used for various purposes.
As such a pressure sensor for detecting fluid pressure, a pressure sensor such as a piezoresistive element is enclosed in a sealed chamber (liquid sealed chamber) separated from a non-measuring fluid area by a diaphragm and filled with an incompressible fluid such as oil. There is known a liquid-sealed pressure sensor in which an element is arranged to transmit a fluid pressure of a non-measuring fluid acting on a diaphragm to a pressure detecting element via an incompressible fluid in a liquid-sealed chamber (Patent Document 1). ).
In recent years, with the progress of semiconductor technology, one-chip semiconductor pressure sensors in which a pressure detection element and a signal processing circuit are integrated on the same silicon chip have been developed.
[0003]
FIG. 2 is a diagram showing the configuration of such a conventional liquid-sealed one-chip semiconductor pressure sensor, (a) is a cross-sectional view showing the configuration of the liquid-sealed one-chip semiconductor pressure sensor, and (b) is a semiconductor sensor. It is sectional drawing which expands and shows the part of a chip | tip.
As shown in this figure, the liquid ring type pressure sensor is roughly composed of a pressure detection element 10, a joint part 30, and a connector part 40.
The pressure detection element 10 includes a metal element housing 11, a hermetic glass 13 hermetically fixed to the central opening 12 of the element housing 11, a plurality of lead pins 14 hermetically attached to the hermetic glass 13 in a penetrating manner, an oil It consists of a filling pipe 15 and a sensor chip mount member 16, and a pressure detection sensor chip 18 fixed to the upper end surface of the sensor chip mount member 16 through a glass 17.
As shown in an enlarged view of FIG. 2B, the sensor chip 18 is formed by etching the center of the back surface of the silicon substrate to form a diaphragm (silicon diaphragm). A bridge circuit is formed on the upper part of the silicon diaphragm portion. A plurality of pressure detection elements (piezoresistive elements) 18-1 to be formed are formed, and an electronic circuit such as an amplifier circuit, a linear correction circuit, a temperature correction circuit, and a correction data holding circuit that processes the output signal of the bridge circuit around it 18-2 is integrated by a semiconductor circuit integration technique, and an oxide film 18-3 is formed on the surface side. The pressure detecting sensor chip 18 and the lead pin 14 are connected by a wire (not shown).
[0004]
Further, a metal diaphragm 20 and a diaphragm protective cover 22 having a communication hole 21 for covering the upper edge of the central opening 12 of the element housing 11 are hermetically sealed 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 enclosed.
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 adhered, and the portion is welded. Thereby, the oil is sealed in the liquid sealing chamber 23.
[0005]
The pressure detection element 10 is fitted into the element housing hole 31 of the joint portion 30 together with the O-ring 24. Further, the connector portion 40 is fitted together with the O-ring 25 into the element storage hole 31 of the joint portion 30, and the opening edge portion 32 of the element storage hole 31 is caulked to sandwich the pressure detection element 10. And fixedly coupled.
[0006]
The joint portion 30 is attached to the measured portion by a sensor attaching screw portion 33, and the fluid pressure is transmitted to the metal diaphragm 20 via the measured fluid pressure passage 34. Since the metal diaphragm 20 is very thin, the pressure is transmitted to the oil without being reduced, and the pressure causes the silicon diaphragm of the sensor chip 18 to be deformed, and an electric signal detected by the piezoresistive element 18-1 is an electronic circuit 18 -2 and output to the lead pin 14. An external output substrate 35 such as a flexible printed circuit board (FPC) for electrically connecting the lead pin 14 and the terminal 41 of the connector unit 40 is provided, and an electrical signal from the sensor chip 18 passes through the lead pin 14 and the terminal 41. Will be taken out.
The lead pin 14 is provided with a plurality of lead pins respectively connected to the power supply potential, the zero potential, the output terminal, and one or a plurality of test points of the sensor chip 18, and the terminal 41 includes the lead pin 14. Are connected to the power supply potential, the zero potential, and the pin of the output terminal, respectively, and are provided with three terminals, a ground terminal and an output terminal.
[0007]
[Patent Document 1]
Japanese Patent 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 is 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 source is insulated from the primary power source 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. As a result, the electronic circuit and the non-volatile memory in the sensor chip 18 may be adversely affected.
[0009]
Therefore, the present applicant has proposed a pressure sensor that can prevent the occurrence of adverse effects even when a potential is generated between the apparatus frame ground and the secondary power supply (Japanese Patent Application 2002). -192207).
FIG. 3 is a diagram showing an embodiment of the pressure detection element 10 in the pressure sensor proposed by the present applicant. In addition, the same number is attached | subjected to the same component as the said FIG. 2, and description is abbreviate | omitted. Further, the sensor chip 18 is simply shown and the glass 17 is not shown.
As shown in this figure, in this pressure detection element 10, the height of the outer peripheral part of the hermetic glass 13 is formed higher than the center part, and a ring-shaped metal member 51 is fitted inside the outer peripheral part. 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, the lead pin 14-1 is inserted into the hole, and the metal member 51 is crushed and caulked. Thus, the metal member 51 and the lead pin 14-1 are mechanically and electrically connected. Further, a metal plate 52 is electrically and mechanically connected to the upper surface of the metal member 51 by welding. The metal plate 52 is provided with an opening 53.
[0010]
As a result, the metal plate 52 and the metal member 51 that have the same potential as the zero potential of the electronic circuit integrated on the sensor chip 18 can be disposed between the sensor chip 18 and the metal diaphragm 20. 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, there is a potential difference between the zero potential of the electronic circuit on the sensor chip 18 and the metal plate 52. Since it does not occur, adverse effects on the electronic circuit integrated on the sensor chip 18 can be prevented.
[0011]
However, in the configuration shown in FIG. 3, the glass hermetic treatment is applied to the parts in which the metal member 51 and the zero-potential lead pin 14-1 are crimped. There was a problem that it was difficult.
Further, in the caulking process in which the lead pin 14-1 and the metal member 51 are caulked and connected, very small parts are handled, and thus there is a problem in the management of the mold.
[0012]
Accordingly, 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. The purpose is to do.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a pressure sensor of the present invention includes a metal housing, a sensor chip mounting member that is fixed to a central opening provided in the metal housing and supports the pressure sensor chip, and oil filling A liquid seal comprising a pressure detecting element having a hermetic glass provided with a lead pin for leading an electric signal from the pipe and the pressure sensor chip to the outside, and a metal diaphragm joined to one end face of the housing A pressure sensor of a type, 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, and the zero electric power of the electronic circuit mounted on the conductive member supporting pin and the pressure sensor chip. And it has a means for electrically connecting connected a lead pin.
Further, 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 derives an electrical signal from the pressure sensor chip to the outside. Therefore, the wiring pattern is provided on the external output board for connecting the lead pin and the output terminal.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a configuration of a pressure detection element 10 according to an embodiment of the pressure sensor of the present invention, in which (a) is a cross-sectional view showing the configuration of the pressure detection element 10, and (b) is a pressure detection element 10. FIG. 3 is a diagram showing a state in which an external output substrate 35 made of a flexible printed circuit board (FPC) connected to a terminal of the pressure detection element is viewed from the lower side of FIG. In this figure, the same components as those in FIG. 2 and FIG.
[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, but in this embodiment, as shown in the drawing, the peripheral edge is in the downward direction in the figure (the direction of the sensor chip 18). It has a bent shape. With this shape, the sensor chip 18 can be surrounded.
Reference numeral 14-2 denotes at least three conductive member fixing lead pins provided to support the conductive member 1, and the other lead pins 14, the oil filling pipe 15 and the sensor chip mounting member 16 are provided. Like the above, the hermetic glass 13 is hermetically mounted 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) end of the drawing is in contact with the conductive member 1, and spot welding or the like is used. It is electrically and mechanically connected to the conductive member 1.
[0016]
In FIG. 1B, reference numeral 35 denotes an external output board for connecting the lead pin 14 described with reference to FIG. 2 and the terminal 41 (FIG. 2) of the connector section 40. On the external output board 35, In addition, at least one of the conductive member fixing lead pins 14-2 and a lead pin (zero potential lead pin) 14-connected to the zero potential of the electronic circuit on the sensor chip 18 of the lead pins 14. 1 is provided. The wiring pattern 2 is provided to electrically connect 1 to the wiring pattern 2. The zero potential lead pin 14-1 and the conductive member fixing lead pin 14-2 and the conductive member fixing lead pin 14-2 are soldered to the wiring pattern 2 or laser spot welded, etc. 14-2 can be electrically connected.
Accordingly, 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 zero potential lead pin 14-1, the wiring pattern 2, and the conductive member fixing lead pin 14-2. . Therefore, 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 between the sensor chip 18 and the metal diaphragm 20, and the metal diaphragm 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, adverse effects on the electronic circuit integrated in the sensor chip 18 can be prevented.
[0017]
When manufacturing such a pressure detection element 10, the conductive member fixing lead pins 14-2 (for example, three) are used together with the other lead pins 14, 14-1, the oil filling pipe 15 and the sensor chip mounting member 16. After inserting into the hermetic glass 13 and performing glass hermetic treatment, 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 from the comparison between the shape of the hermetic glass 13 in FIG. 3 and the shape of the hermetic glass 13 in FIG. And glass flowability 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 14-2 are used instead of the metal member 51 in the configuration shown in FIG. 3. 2 and the conductive member 1 are welded and mechanically and electrically connected to each other, and the zero potential lead pin 14-1 and the conductive member fixing lead pin 14-2 are electrically connected in a pattern such as the external output substrate 35. By performing the connection, the same function as in the case of FIG. 3 is achieved.
Therefore, the caulking process can be omitted, and the part cost and the part manufacturing man-hour can be reduced.
[0019]
The shape of the conductive member 1 is not limited to the shape shown in FIG. 1, and can be any 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, but a conductive adhesive is used. Other connection methods may be employed.
Further, the material of the conductive member 1 is not limited to metal, and any conductive resin can be used as long as it can be electrically and mechanically connected to the lead pin 14-2 for fixing the conductive member. Can be used.
Furthermore, in the above-described embodiment, an external output board 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. However, the present invention is not limited to this, and the conductive component that engages with both the zero potential lead pin 14-1 and the conductive member fixing lead pin 14-2 is used. May be inserted or inserted.
[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 source. In addition, non-volatile memory and the like can be prevented from being adversely affected.
And, 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 substrate 35 or the like, the caulking step is omitted. Effects such as reduction of parts costs and parts man-hours can be achieved.
In addition, the reliability of the glass hermetic and the glass flowability can be improved, and the yield of non-defective parts can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a pressure detection element in an embodiment of a pressure sensor according to the present invention, wherein (a) is a cross-sectional view of the pressure detection element, and (b) is a pressure detection element and the pressure detection element. It is a figure which shows a mode that the board | substrate for external output which consists of a flexible printed circuit board (FPC) etc. which are connected to a terminal was seen from the downward direction in (a) figure.
2A and 2B are diagrams showing a conventional liquid-sealed one-chip semiconductor pressure sensor. FIG. 2A is a cross-sectional view showing the configuration of the liquid-sealed one-chip semiconductor pressure sensor, and FIG. 2B is an enlarged view of the semiconductor sensor chip. It is sectional drawing shown.
FIG. 3 is a cross-sectional view showing a configuration example of a pressure detection element in a proposed pressure sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Conductive member 2 Wiring pattern 10 Pressure detection element 11 Element housing 12 Center opening part 13 Hermetic glass 14 Lead pin 14-1 Zero potential lead pin 14-2 Conductive member fixing lead pin 15 Oil filling pipe 16 Sensor chip mounting member 18 Pressure detecting sensor chip 20 Metal diaphragm 35 External output substrate

Claims (2)

A metal housing and a sensor chip mount member that is fixed to a central opening provided in the metal housing and supports the pressure sensor chip, an oil filling pipe, and an electrical signal from the pressure sensor chip are led out to the outside. A liquid ring type pressure sensor including a pressure detecting element having a hermetic glass provided with a lead pin for performing the above and a metal diaphragm joined to one end face of the housing,
A conductive member disposed between the pressure sensor chip and the metal diaphragm;
A conductive member supporting pin provided on the hermetic glass and electrically and mechanically connected to the conductive member;
A pressure sensor comprising: 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. 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 is for deriving an electric signal from the pressure sensor chip to the outside. 2. The pressure sensor according to claim 1, wherein the pressure sensor is a wiring pattern provided on an external output substrate for connecting the lead pin and the output terminal.

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