JP2003262560A - Pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure sensor for simpler configuration, which allows re-trimming. <P>SOLUTION: An input/output pin and a trimming pin are all provided on a single pin header 7 provided on an HIC2. A potting part 12 is so provided as to cover the surface of pin header 7, so that the input/output pin and the trimming pin are kept exposed. <P>COPYRIGHT: (C)2003,JPO

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 measuring fluid pressure.

[0002]

2. Description of the Related Art Conventionally, this type of pressure sensor has been used in the field of various construction machines, industrial equipment, etc., for measuring various fluid pressures such as hydraulic pressure in a hydraulic circuit.

An example of a conventional pressure sensor is shown in FIG.
And FIG. 4 will be described. FIG. 3 is a schematic sectional view of a pressure sensor according to the related art. FIG. 4 is a plan view of a HIC (hybrid IC) in a pressure sensor according to the related art.

A pressure sensor 101 according to the prior art generally includes a HIC (hybrid IC) 102 provided with an ASIC (application-specific IC) 103, and a sub-circuit 104 having a circuit for converting an electric signal. A sensor chip 106 for detecting pressure and a pin 105 for electrically connecting the sensor chip 106 and a circuit on the sub-circuit 104 are provided.

The pressure sensor 101 is a HIC 102.
Terminal pin 11 electrically connected to the HIC 102 via the upper output lands 114a, 114b, 114c
3, the feedthrough capacitor 110 provided so that the terminal pin 113 penetrates, and the flexible flat cable 109 electrically connected to the terminal pin 113.
And a connector 108 for electrically connecting to the outside via a flexible flat cable 109.

Further, a trimming connector 107 is provided for external electrical connection when the ASIC 103 is trimmed during the manufacturing process.

The HIC 102, ASIC 103, sub-circuit 104 and the like are sealed and fixed by a potting agent. The potting portion 112 sealed and fixed in this manner improves vibration resistance, thermal coupling, and corrosion resistance.

With the above structure, in the pressure sensor 101, when the sensor chip 106 receives pressure, the sensor chip 106 converts the pressure into an electric signal according to the magnitude of the pressure. The electrical signal is converted to the sub-circuit 104 through the pin 105 and then transmitted to the HIC 102.

The ASI provided in the HIC 102
The electric signal is amplified and corrected by C103. The corrected output signal is sent from the output lands 114a to 114c on the HIC 102 to the outside through the terminal pin 113 and further through the flexible flat cable 109 connected to the terminal pin 113.

Since it is necessary to trim the ASIC 103 in the middle of the manufacturing process of the pressure sensor 101, the trimming connector 107 is formed after assembling various substrates and electronic parts and before the potting portion 112 is formed. Trimming was done by connecting the mating connector for trimming to.

As described above, the pressure sensor 101 needs two types of I / O units for exchanging signals with the outside. That is, one is an I / O for a power supply, an output, and a GND required for use as a product, and the other is an I / O for digital trimming.

The former is used as a product, while the latter is usually used only once during the manufacturing process.
In the prior art, each I / O employs a different electrical bonding method because it is unnecessary after the product is completed.

However, since the two types of electric joining methods are adopted, the number of parts is increased and the structure is complicated,
As a result, it was a cause of increasing costs.

Further, in the above-mentioned conventional technique, the terminal portion of the trimming connector 107 is also covered with the potting agent by the formation of the potting portion 112 due to its constitution. This is the trimming connector 10
Since there is a lateral hole in 7, the potting agent enters the inside of the trimming connector 107, and the trimming connector 107 is normally used only once, so that the trimming connector 107 can be reused by design. It was because it was not configured in.

Therefore, after forming the potting portion 112, re-trimming could not be performed.

However, the accuracy of the ASIC 103 is not within the allowable range at the final inspection stage due to some influence (for example, when the device is abnormal in the manufacturing process or pressure control error) after the trimming is performed once. In some cases, trimming may be necessary again. In such a case, in the conventional technique, since re-trimming is impossible, such products must be disposed of such as discarded.

[0017]

As described above, in the case of the prior art, there is a problem that the number of parts is increased and the structure is complicated. There is also a problem that re-trimming cannot be performed.

It is an object of the present invention to provide a pressure sensor having a simplified structure and enabling re-trimming.

[0019]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a substrate with different types of input / output electrical connection portions used for exchanging electrical signals with the outside of the device. Configured as one above.

Here, the input / output electrical connection portion is an input / output pin for exchanging electrical signals between the pressure detecting means and the outside, and a trimming for exchanging electrical signals for adjusting the ASCI in the manufacturing process. It is a pin for.

The ASIC is for amplifying and correcting the output signal obtained from the pressure detecting means, and is necessary when using the pressure sensor. The input / output pins are used when the product is used to exchange these signals. Also, the ASIC needs to be trimmed during the manufacturing process. The trimming pin is used for trimming the ASIC in the manufacturing process.

The number of these input / output pins and trimming pins is set according to the needs of the product, and the number is not limited.

These input / output pins and trimming pins are integrated into one pin header on the substrate on which the ASIC is provided.

Also, the vibration resistance of the pin header and the substrate can be improved by filling and fixing the portion including the pin header and the substrate with the filler while leaving the portions of the input / output pin and the trimming pin exposed. In this case, since the portion of the trimming pin is exposed, trimming is possible even after the filling and fixing with the filler.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions of the components described in this embodiment,
Unless otherwise specified, the material, the shape, the relative arrangement, and the like are not intended to limit the scope of the present invention thereto.

A pressure sensor according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic sectional view of a pressure sensor according to an embodiment of the present invention.
FIG. 2 shows H in the pressure sensor according to the embodiment of the present invention.
It is a top view of IC (hybrid IC).

The pressure sensor 1 according to the present embodiment is generally a HI provided with an ASIC (application specific IC) 3.
A C (hybrid IC) 2, a sub-circuit 4 having a circuit for converting an electric signal, a sensor chip 6 for detecting pressure, and a sensor chip 6 and a circuit on the sub-circuit 4 are electrically connected. And a pin 5 for connection. The sensor chip 6 and the pin 5 are electrically connected via the bonding wire 13 or the like.

The sensor chip 6 uses a strain gauge in this embodiment, and is provided with four gauge films (strain gauges), and a gauge pattern is formed by these gauge films to form a circuit. When the pressure (stress) on the sensor chip 6 changes, the sensor chip 6 deforms accordingly, and the strain amount of each gauge film changes.

Since the stress coefficient on the sensor chip 6 differs depending on the position, the strain amount of each gauge film is not uniform. As a result, the strain amount of each gauge film changes in accordance with the pressure change, and the electric resistance of each gauge film also changes. Therefore, since each resistance value of each gauge film portion changes according to the pressure, the output voltage with respect to the input voltage changes, and this output voltage changes linearly according to the pressure change. It can be measured.

In the case of the present embodiment, a cover 61 having a plurality of holes at the tip of the pressure sensor 1, a diaphragm 62 provided inside the cover 61, and a guide 63 having a through hole.
Is provided, and the sensor chip 6 is provided inside thereof. The inside of the sealed space formed by the diaphragm 62 and the sensor chip 6 is filled with silicone oil.

As a result, the external fluid enters the inside of the cover 61, so that the fluid pressure directly acts on the diaphragm 62. Therefore, the diaphragm 62 deforms according to the pressure received. This deformation amount (strain amount) corresponds to the pressure applied to the diaphragm 62. Then, according to the deformation, the sensor chip 6 is deformed by receiving pressure through the silicon oil, and the pressure can be measured as described above. The guide 63 is provided with a through hole at a portion corresponding to the sensor chip 6 so that the pressure can be accurately transmitted to the sensor chip 6 portion through the silicone oil.

Further, four pins 5 for input / output are provided for exchanging electric signals with the sensor chip 6. And because of space, HIC2
Since the pin 5 cannot be directly attached to the board by soldering, the sub-circuit 4 having a circuit for converting an electric signal is provided. As a result, the output signal from the sensor chip 6 is sent to the sub-circuit 4 via the pin 5, where the electric signal is converted and then sent to the HIC 2.

The pressure sensor 1 has four input / output pins 71a, 71b, 71 electrically connected to the HIC 2.
c, 71d and a flexible flat cable 9 whose one end is electrically connected to these input / output pins 71a to 71d.
A connector terminal 81 electrically connected to the other end of the flexible flat cable 9; a connector 8 for electrically connecting the connector terminal 81 to an external device; And a feedthrough capacitor 10.

One end of the flexible flat cable 9 is directly soldered to the input / output pins 71a to 71d. The feedthrough capacitor 10 is fixed to a plate 11 supported by the case.

Further, the pressure sensor 1 is provided with an ASIC 3,
Trimming pins 71e, 71f, 71 for electrical connection from the outside when trimming in the middle of manufacturing
g, 71h, 71i, 71j, 71k, 71l are provided.

In this embodiment, as is clear from FIG. 2, the input / output pins 71a to 71d and the trimming pins 71e to l are all provided on one pin header 7 provided in the HIC 2. Has been. In the pin header 7, as shown in the drawing, the input / output pins 71a to 71d
Area 71 in which is arranged and trimming pin 71e
A second region 72 is formed in which ~ l is arranged.

When trimming the ASIC 3,
The trimming pins 71e to 71 are joined to unillustrated receptacles (female connectors) provided in the trimming device to perform trimming.

The HIC2, ASIC3, sub-circuit 4, etc. are sealed and fixed by a potting agent. The purpose of providing the potting portion 12 for sealing and fixing will be described.

The first is to improve the vibration resistance.
That is, if the substrate or the like is not sealed and fixed, the substrate may shake due to the vibration, and the pins or the like may be broken. In order to prevent this, the potting part 1
2, the various members such as the substrate are constrained and fixed to improve the vibration resistance.

The second is to improve the thermal bondability. The ASIC 3 has a temperature sensitive element built therein. This is because the strain deformation degree of the sensor chip 6 differs depending on the environmental temperature, and thus the output data is corrected according to the environmental temperature. Therefore, it is desirable that the temperature sensitive element and the sensor chip 6 have the same temperature as much as possible. Therefore, in order to make the temperatures as equal as possible, the potting portion 12 is used to improve the thermal coupling between the ASIC 3 and the case or the like.

Thirdly, it is intended to improve the corrosion resistance of the substrate and the like. That is, if the substrate or the like is not sealed and fixed, the substrate or the like may be corroded by the influence of humidity or the like. In order to prevent this, the potting portion 12 covers the surface of the substrate or the like to improve the corrosion resistance.

In the present embodiment, the potting portion 12 is provided to the extent that it covers the surface of the pin header 7, and the input / output pins 71a to 71d and the trimming pin 7 are provided.
1e to 1 maintain the exposed state.

With the above configuration, in the pressure sensor 1 according to this embodiment, when the sensor chip 6 receives pressure, the sensor chip 6 converts the pressure into an electric signal according to the magnitude of the pressure. The electric signal is converted to the sub-circuit 4 through the pin 5 and then transmitted to the HIC 2.

Then, the ASIC3 provided in the HIC2
The electrical signal is thereby amplified and corrected. The corrected output signals are input / output pins 71a to
From d, it is sent to the connector terminal 81 through the flexible flat cable 9, and is sent to the external device via the mating connector connected to the connector 8.

As described above, in the present embodiment,
I / O of different types provided for exchanging signals inside and outside the device, that is, input / output pin 7
1a-d and the trimming pins 71e-l are gathered in one place by one pin header 7.

Therefore, the number of parts can be reduced, and the structure can be simplified. Also, HIC
The space above 2 can be saved significantly, and the degree of freedom in design can be improved. In fact, by adopting this configuration, even a circuit of current output type, which is disadvantageous in comparison with the voltage type in terms of space, can be accommodated in the HIC of the same size.

Also, with the reduction of the number of parts and the abolition of the costly trimming connector and the like,
It has also become possible to reduce costs. In addition, the simplification of the configuration also improves the assemblability.

In the present embodiment, the trimming pins 71e to 71e are not buried in the potting portion 12 but exposed, so that the ASIC 3 is trimmed even after the potting portion 12 is formed. Is possible.

Therefore, even if the accuracy of the ASIC 3 is out of the allowable range due to some influence after the trimming is performed once in the manufacturing process, the re-trimming can be performed and the yield is improved. be able to.

That is, it is usually sufficient to perform the trimming once, but due to an abnormality in the device, an error in pressure control, or the like,
The accuracy of the ASIC 3 may fall outside the allowable range. On the other hand, the pressure sensor 1 is a completed product by caulking the connector 8 in the case (body), but the final inspection of the pressure sensor 1 is performed with the connector 8 temporarily inserted in the case. Therefore, even when it is found that the accuracy of the ASIC 3 is out of the allowable range at the final inspection stage, re-trimming can be performed unlike the conventional technique, so that defective products can be reduced and yield can be improved. It becomes possible.

[0051]

As described above, according to the present invention, the structure can be simplified. Further, re-trimming can be performed even after filling and fixing with the filler.

[Brief description of drawings]

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

FIG. 2 is a plan view of the HIC in the pressure sensor according to the embodiment of the present invention.

FIG. 3 is a schematic sectional view of a pressure sensor according to a conventional technique.

FIG. 4 is a plan view of a HIC (hybrid IC) in a pressure sensor according to a conventional technique.

[Explanation of symbols]

1 Pressure Sensor 2 HIC (Hybrid IC) 3 ASIC (Application Specific IC) 4 Sub Circuit 5 Pin 6 Sensor Chip 7 Pin Header 8 Connector 9 Flexible Flat Cable 10 Penetrating Capacitor 11 Plate 12 Potting Part 13 Bonding Wire 61 Cover 62 Diaphragm 63 Guide 71a, 71b, 71c, 71d Input / output pins 71e, 71f, 71g, 71h, 71i, 71j, 7
1k, 71l Trimming pin 81 Connector terminal

Claims (2)

[Claims] 1. An ASIC for amplifying and correcting an output signal obtained from a pressure detecting means, a substrate provided with the ASIC, a signal provided on the substrate and amplified and corrected by the ASIC, An input / output pin serving as an electrical connection portion for exchanging an electrical signal between the pressure detection means and the outside; a trimming pin serving as an electrical connection portion for exchanging an electrical signal for trimming the ASCI in a manufacturing process; A pressure sensor comprising: the input / output pin and the trimming pin, each of which is provided in one pin header. 2. The part including the pin header and the substrate is filled and fixed with a filler while the parts of the input / output pin and the trimming pin are exposed. Pressure sensor.