JP2003194768A - Water sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water sensor for securing high reliability regardless of a long-term wetting state. <P>SOLUTION: The water sensor 30 comprises an operation electrode 24 that provides a sensor chip 4 having an ion-sensitive-type field effect transistor 29, and a comparison electrode 22. In the water sensor 30, a printed circuit board 1 having an electrode section 2 at the side of the printed circuit board for external connection, and a wire-bonding electrode section 3 at the side of the printed circuit board for connecting chip sensors is provided inside a forming body 8 for forming the appearance of the counter electrode 24. At the same time, the sensor chip 4 is provided on the printed circuit board 1. The sensor chip side wire-binding electrode section 6 that is provided at the sensor chip 4, and the printed circuit board side wire bonding electrode section 2 of the printed circuit board 1, are connected by a wire 5, thus sealing at least the connection section in the forming body 8 by resin 9. <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 water quality sensor for measuring ion concentration, and more particularly to a sensor mounting structure.

[0002]

2. Description of the Related Art As a water quality sensor using an ion sensitive field effect transistor, for example, Japanese Patent Application No. 50-102678.
There is an ion sensor described in Japanese Patent Application Publication No. Hei 5-1.
It is proposed in Japanese Patent No. 28735.

When a sensor chip using a semiconductor and an external electrode are bonded to each other in a water quality sensor, bump bonding as described in Japanese Patent Application Laid-Open No. 4-258755 has been conventionally used as a bonding method. However,
In the water treatment equipment incorporating the water quality sensor as described above, the water quality sensor is always in a wet state, and in the case where bump bonding is performed, there is no problem in a short-time wet state but a long-term wet state. For example, there was a problem with reliability such as insulation failure due to corrosion of the joint.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a water quality sensor that ensures high reliability even in a long-term wet condition. It is a thing.

[0005]

In order to solve the above-mentioned problems, the first aspect of the present invention provides a water quality sensor comprising a working electrode provided with a sensor chip having an ion-sensitive field effect transistor and a reference electrode. The molded body forming the outer shape of the working electrode is provided with a printed circuit board provided with an electrode part for external connection and a wire bonding electrode part for sensor chip connection, and the sensor chip is arranged on the printed circuit board. The wire bonding electrode portion provided on the printed circuit board and the wire bonding electrode portion of the printed circuit board are connected by a wire, and at least the connection portion inside the molded body is resin-sealed. By doing so, watertightness is secured by resin sealing, and high reliability is secured even in a long-term wet state such as being incorporated into a domestic water treatment device for use.

Further, in order to solve the above-mentioned problems, the second invention is to provide a water quality sensor comprising a working electrode provided with a sensor chip having an ion-sensitive field effect transistor and a reference electrode, and the outer shape of the working electrode. In the reinforcing plate installed inside the molded body forming the, the flexible printed circuit board and the sensor chip, which are provided with an electrode part for external connection and a wire bonding electrode part for sensor chip connection, are arranged adjacent to each other, The wire bonding electrode portion provided on the sensor chip and the wire bonding electrode portion of the flexible printed circuit board may be connected by a wire, and at least the connection portion inside the molded body may be resin-sealed. By doing so, watertightness is secured by resin sealing, and high reliability is secured even in a long-term wet state such as being incorporated into a domestic water treatment device for use.

Further, in order to solve the above-mentioned problems, the third invention is to provide a water quality sensor comprising a working electrode provided with a sensor chip having an ion-sensitive field effect transistor and a reference electrode, and the outer shape of the working electrode. Inside the molded body forming the, the flexible printed circuit board and the sensor chip, which are provided with an electrode portion for external connection and a wire bonding electrode portion for sensor chip connection, are arranged adjacent to each other,
The wire bonding electrode portion provided on the sensor chip and the wire bonding electrode portion of the flexible printed circuit board may be connected by a wire, and at least the connection portion inside the molded body may be resin-sealed. By doing so, watertightness is secured by resin sealing, and high reliability is secured even in a long-term wet state such as being incorporated into a domestic water treatment device for use.

Further, in order to solve the above-mentioned problems, a fourth invention is directed to a water quality sensor comprising a working electrode provided with a sensor chip having an ion-sensitive field effect transistor and a reference electrode, and the outer shape of the working electrode. A wire provided on the sensor chip, in which a conductive plate formed with an electrode portion for external connection and a wire bonding electrode portion for sensor chip connection and a sensor chip are arranged adjacent to each other inside the molded body forming The water quality sensor may be characterized in that the bonding electrode portion and the wire bonding electrode portion of the conductive plate are connected by a wire, and at least the connection portion inside the molded body is resin-sealed. By doing so, watertightness is secured by resin sealing, and high reliability is secured even in a long-term wet state such as being incorporated into a domestic water treatment device for use.

Further, as a fifth invention, in the second or third invention, it is also preferable to provide a wire bonding electrode portion for connecting a sensor chip at an end portion of the flexible printed circuit board. Since the flexible printed circuit board and the sensor chip can be arranged at a predetermined distance and the respective wire bonding electrode portions can be connected by wires, it is not necessary to form the flexible printed circuit board in a large size.

As a sixth invention, in the second or third invention, it is also preferable that the wire bonding electrode portion for connecting the sensor chip is provided at a position sandwiched by both ends of the flexible printed circuit board. By doing so, the sensor chip can be arranged on the portion of the flexible printed circuit board between the end portion and the wire bonding electrode portion, and at that time, the sensor chip can be arranged on the portion of the flexible printed circuit board where the sensor chip is arranged. By indicating a positioning line or providing a hole for accommodating the sensor chip or the like, it becomes easy to position each wire bonding electrode portion, and highly accurate wire bonding becomes possible.

As a seventh invention, in any one of the third, fifth and sixth inventions, it is preferable that the flexible printed circuit board is insert-molded inside the molded body.
By doing so, the flexible printed circuit board is integrated with the molded body to improve reliability, and since the internal space of the molded body is eliminated, the resin sealing process is reduced and the manufacturing is simplified.

Further, as an eighth invention, in the fourth invention, it is also preferable that the conductive plate is insert-molded inside the molded body. By doing so, the conductive plate is integrated with the molded body and reliability is improved. In addition, since the internal space of the molded body is eliminated, the resin sealing process is reduced and the manufacturing is simplified.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the embodiments shown in the accompanying drawings. 1 to 3 show the working electrode 24 of the first example in the embodiment of the present invention and each member incorporated therein. A plurality of electrode portions are printed on the printed circuit board 1, and one end side of each electrode portion forms a printed circuit board side electrode portion 2 for external connection. On the other end side of each electrode part, a printed board side wire bonding electrode part 3 for connecting a sensor chip is formed,
The surface is subjected to surface treatment with Ni and Au for wire bonding. Further, a sensor chip 4 is arranged on the printed circuit board 1 adjacent to the printed circuit board side wire bonding electrode portion 3, and the sensor chip 4 has a sensitive film and a temperature for measuring hydrogen ion concentration and calcium ion concentration. An ion-sensitive field effect transistor (hereinafter, abbreviated as ISFET) 29 including a correction diode is provided. A sensor chip side wire bonding electrode portion 6 is provided on an end portion of the sensor chip 4 adjacent to the printed board side wire bonding electrode portion 3,
The sensor chip side wire bonding electrode portion 6 and the printed board side wire bonding electrode portion 3 are electrically connected by a gold wire 5. Further, a lead wire 7 for communicating with an external input / output device such as an amplifier circuit 23 is connected to the printed board side electrode portion 2 formed on the printed board 1.

The printed circuit board 1 and the members arranged therein are housed and held inside a molded body 8 forming the outer shape of the working electrode 24. Further, in order to ensure reliability even in a wet condition for a long period of time, the connection portion between the wire bonding electrode portion 3 of the printed circuit board side and the wire bonding electrode portion 6 of the sensor chip side and the wire 5 and the metal exposed portion of the printed circuit board 1 And the space inside the molded body 8 including the connection part between the printed circuit board side electrode portion 2 and the lead wire 7 is sealed with the resin 9. The resin 9 is preferably silicone or epoxy resin from the viewpoint of both waterproofness and durability. In addition, a thermosetting material may be used in terms of adhesion with the molded body 8. In this case, the molded body 8 is formed of a heat resistant material such as PPS.

Next, a second example of the embodiment of the present invention will be described with reference to FIGS. A flexible printed circuit board (hereinafter, abbreviated as FPCB) 28 shown in FIG. 6 is formed by including a plurality of electric wiring circuits formed of thin conductor foils 11 inside an insulating film 10 such as polyimide. The flexible printed circuit board side electrode portion for external connection (hereinafter, F
A PCB side electrode portion) 12 is formed, and a flexible printed circuit board side wire bonding electrode portion (hereinafter abbreviated as FPCB side wire bonding electrode portion) 13 for sensor chip connection is formed on the other end side. The FPCB side electrode portion 12 for external connection is made of a conductive material and surface-treated, and the FPCB side wire bonding electrode portion 13 is made of Ni.
And Au are surface-treated. Also, this FPC
B28 is adhered to the reinforcing plate 14 as shown in FIG. 5 and the like to facilitate wire bonding. The reinforcing plate 14 is made of a heat-resistant material such as glass epoxy so that it can withstand heat during wire bonding.

Further, the sensor chip 4 is disposed on the reinforcing plate 14 adjacent to the FPCB side wire bonding electrode portion 13. The sensor chip 4 is the same as that of the first example, and the sensor chip side wire bonding electrode portion 6 provided in the center chip 4 and the FPCB provided in the FPCB 28.
The side wire bonding electrode portion 13 is connected to the gold wire 5
It is electrically connected by. Reinforcing plate 14 described above
And each member arranged therein are housed and held inside the molded body 8 forming the outer shape of the working electrode 24, and at least the FPCB side wire is secured in order to ensure reliability even in a wet state for a long period of time. A resin 9 is used to seal a space in the molded body 8 including the bonding electrode portion 13, the sensor chip side wire bonding electrode portion 6 and the connection portion of the wire 5. As the resin 9, the same resin as in the first example is used.

Next, a third example of the embodiment of the present invention will be described with reference to FIG. However, the description of the same configuration as the second example is partially omitted, and the characteristic configuration will be described below. In the working electrode 24 of this example, the FPCB 28 is directly fixed to the inner surface of the molded body 8 with an adhesive or the like instead of providing the reinforcing plate 14 inside the molded body 8 as in the second example. , Like this FPCB2
The sensor chip 4 is arranged on the inner surface of the molded body 8 which is integrated with 8 and adjacent to the FPCB side wire bonding electrode portion 13, and the sensor chip 4 and the FPCB 28 are connected by the gold wire 5. . Then, as in the second example, at least the space portion inside the molded body 8 including the connection points is sealed with the resin 9 to improve reliability in a wet state.

In this case, the FPCB2 is compared with the second example.
Since it is not necessary to provide the reinforcing plate 14 for fixing the eight, the number of parts is reduced, the space portion in the molded body 8 is small, and the work of resin sealing is also simplified.

FIG. 8 shows the positional relationship between the FPCB 28 and the sensor chip 4 of this example. As described above, in this example, the FPCB side wire bonding electrode portion 13 is connected to the FP.
The FPCB 28 is provided at the end of the CB 28 and from the end where the FPCB side wire bonding electrode portion 13 is provided.
The sensor chip 4 is arranged at a position separated by a predetermined distance from the sensor chip 4. On the other hand, as shown in FIG.
The side wire bonding electrode portion 13 is provided at a position sandwiched between both ends of the FPCB 28, and the end portion of the FPCB 28 and the F
The sensor chip 4 may be arranged at a location between the PCB side wire bonding electrode section 13 and the opposite side of the FPCB side electrode section 12. At that time, FPCB28
By arranging a positioning line in the upper portion where the sensor chip 4 is arranged or by providing a hole in which the sensor chip 4 can be accommodated, the sensor chip side wire bonding electrode portion 6 and the FPCB side wire bonding electrode portion 13 are separated. Positioning becomes easier, and highly accurate wire bonding becomes possible.

In addition, the same arrangement as the arrangement of the FPCB 28 and the sensor chip 4 of the present example described above is applied to the working electrode 2 of the second example.
It may be used for 4.

Next, a fourth example of the embodiment of the present invention will be described with reference to FIG. However, the description of the same configuration as the second example is partially omitted, and the characteristic configuration will be described below. In the working electrode 24 of this example, the conductive plate 15 formed of the conductive plate side electrode portion 31 for external connection and the electrode plate side wire bonding electrode portion 16 for sensor chip connection is formed on the molded body 8. The wire bonding electrode portion 16 is provided on the inner surface of the molded body 8 integrally fixed to the inner surface of the electrically conductive plate 15 at the end portion of the electrically conductive plate 15. The sensor chip 4 is arranged at an adjacent position, and the sensor chip side wire bonding electrode portion 6 and the conductive plate side wire bonding electrode portion 16 are connected by the gold wire 5. Then, as in the second example, the space portion inside the molded body 8 including at least the connection portion is sealed with the resin 9 to improve reliability in a wet state.

Also in this example, since it is not necessary to provide a member such as the reinforcing plate 14 used in the second example, the number of parts can be small and the space in the molded body 8 can be small, and the resin can be used. The work of sealing is simplified.

Next, a fifth example of the embodiment of the present invention will be described with reference to FIG. The working electrode 24 of this example is substantially the same as that of the third example, and the description of the same configuration is omitted, but it is different from the third example in that the FPCB 28 is insert-molded inside the molded body 8. It has a characteristic structure. By performing the insert molding in this way, the positioning of the FPCB 28 is performed accurately, and since the space between the molded body 8 and the FPCB 28 is eliminated, the sealing process by the resin 9 can be reduced. Further, as in the third example, as compared with the second example, a member such as the reinforcing plate 14 is not necessary, so the number of parts is reduced.

Next, a sixth example of the embodiment of the present invention will be described with reference to FIG. The working electrode 24 of this example is substantially the same as that of the fourth example, and the description of the same configuration is omitted, but it is the fourth example that the conductive plate 15 is insert-molded inside the molded body 8. It has a characteristic configuration different from. By performing the insert molding in this way, the conductive plate 15 is accurately positioned, and the space between the molded body 8 and the conductive plate 15 is eliminated, so that the sealing process by the resin 9 can be reduced. .

Next, the working electrode 2 of any one of the examples described above.
A water quality sensor 30 provided with 4, which is used by being incorporated into a flow path in a domestic water treatment device will be described with reference to FIGS. 13 to 15. As shown in FIG. 15, the inside of the main body case 17 of the water quality sensor 30 is divided into two parts, and in one of the divided parts, an upper packing 18 made of silicon and a lower packing 20 having a liquid junction ceramic 19 are provided. It has a space sandwiched between and. The space is filled with saturated KCl21 containing CMC for adjusting the elution amount from the liquid junction ceramic 19 during long-term use, and further, inside the saturated KCl21, Ag / Ag is contained.
The reference electrode 22 formed of Cl or the like is located. ISFE is provided in the other internal space of the main body case 17 which is divided.
The amplifier circuit 23 for processing the input and output of T29 is arranged, and the upper portion of the working electrode 24 is fitted and positioned from the lower side. Further, this internal space is sealed with a potting agent using urethane resin for waterproofing in consideration of use in domestic water treatment equipment, etc., and the potting agent is prevented from leaking to the upper outer periphery of the working electrode 24. For the purpose, a leak prevention O-ring 26 is fitted. Further, the amplifier circuit 23 is electrically connected to the electrode portion for external connection built in the working electrode 24 and the comparison electrode 22, respectively.

In addition, a main body cap 25 is provided on the upper part of the main body case 17 for the purpose of waterproofing, and the water quality sensor 30 is installed at the place where the main body case 17 and the working electrode 24 are incorporated in the flow path. Waterproof O-rings 27 are fitted to each other for the purpose of preventing water leakage from the flow channel when incorporated into the flow channel in the device.

According to the water quality sensor 30 as described above, even when the water quality sensor 30 is installed in a water treatment apparatus and is always in a wet state, the connection points in the working electrode 24 and High reliability is ensured because the exposed metal portion, the space inside the molded body 8 and the like are preferably resin-sealed.

[0028]

As described above, in the inventions according to claims 1 to 4, the watertightness is ensured by the resin sealing, and it is used in a long-term wet state such that it is incorporated into a domestic water treatment equipment for use. Even if there is, there is an effect that high reliability is secured.

According to the invention of claim 5, in addition to the effect of the invention of claim 2 or 3, the flexible printed circuit board and the sensor chip are arranged at a predetermined distance from each other. Since the bonding electrode portions can be connected by wires, there is an effect that it is not necessary to form the flexible printed circuit board in a large size.

According to the invention of claim 6, in addition to the effect of the invention of claim 2 or 3, a flexible printed circuit board is provided between the end portion and the wire bonding electrode portion. Since it is possible to place the sensor chip in that part, at that time, each wire can be provided by indicating a positioning line in the sensor chip placement part on the flexible printed circuit board or providing a hole in which the sensor chip can be placed. There is an effect that the positioning of the bonding electrode portion is facilitated and highly accurate wire bonding becomes possible.

According to the invention of claim 7, in addition to the effect of the invention of claim 3, 5, or 6,
The flexible printed circuit board is integrated with the molded body to improve reliability, and since the internal space of the molded body is eliminated, the resin sealing process is reduced and manufacturing is simplified.

According to the invention of claim 8, in addition to the effect of the invention of claim 4, the conductor plate is integrated with the molded body to improve reliability, and the internal space of the molded body is improved. Since there is no such problem, there is an effect that the resin sealing process is reduced and the manufacturing is simplified.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a working electrode of a first example in an embodiment of the present invention.

FIG. 2 is a schematic side view showing each member housed in the molded body of the working electrode of the above.

FIG. 3 is a schematic plan view showing each member housed in the molded body of the working electrode of the same.

FIG. 4 is a schematic sectional view showing a working electrode of a second example in the embodiment of the present invention.

FIG. 5 is a schematic side view showing each member housed in the molded body of the working electrode of the same.

FIG. 6 is a schematic plan view showing each member housed in the molded body of the working electrode of the same.

FIG. 7 is a schematic cross-sectional view showing a working electrode of a third example in the embodiment of the present invention.

FIG. 8 is a schematic plan view showing each member housed in the molded body of the working electrode of the above.

FIG. 9 is a schematic plan view showing another arranging means of each member housed in the molded body of the working electrode of the same.

FIG. 10 is a schematic cross-sectional view showing a working electrode of a fourth example in the embodiment of the present invention.

FIG. 11 is a schematic sectional view showing a working electrode of a fifth example in the embodiment of the present invention.

FIG. 12 is a schematic cross-sectional view showing a working electrode of a sixth example in the embodiment of the present invention.

FIG. 13 is a perspective view showing a water quality sensor using any of the working electrodes of the first to sixth examples in the embodiment of the present invention.

FIG. 14 is an exploded view showing the above water quality sensor.

FIG. 15 is a schematic cross-sectional view showing the above water quality sensor.

[Explanation of symbols]

1 Printed Circuit Board 2 Printed Circuit Board Side Electrode Section 3 Printed Circuit Board Side Wire Bonding Electrode Section 4 Sensor Chip 5 Wire 6 Sensor Chip Side Wire Bonding Electrode Section 7 Lead Wire 8 Molded Body 9 Resin 12 Flexible Printed Circuit Board Electrode Section 13 Flexible Printed Circuit Board Side wire bonding electrode portion 14 reinforcing plate 15 conductive plate 16 electrode plate side wire bonding electrode portion 22 reference electrode 24 working electrode 28 flexible printed circuit board 29 ion sensitive field effect transistor 30 water quality sensor 31 conductive plate side electrode portion

Claims (8)

[Claims] 1. A water quality sensor comprising a working electrode provided with a sensor chip having an ion-sensitive field effect transistor and a reference electrode, wherein an electrode portion for external connection is provided inside a molded body forming the outer shape of the working electrode. A printed circuit board provided with a wire bonding electrode part for connecting the sensor chip and a sensor chip on the printed circuit board, and the wire bonding electrode part provided on the sensor chip and the wire bonding electrode part of the printed circuit board. A water quality sensor characterized in that it is connected by a wire, and at least the connection portion inside the molded body is resin-sealed. 2. A water quality sensor comprising a working electrode provided with a sensor chip having an ion-sensitive field effect transistor and a reference electrode, wherein a reinforcing plate installed inside a molded body forming the outer shape of the working electrode is externally mounted. A flexible printed circuit board formed by including an electrode portion for connection and a wire bonding electrode portion for connecting a sensor chip and a sensor chip are arranged adjacent to each other, and a wire bonding electrode portion and a flexible printed circuit provided on the sensor chip. A water quality sensor characterized in that a wire bonding electrode portion of a substrate is connected by a wire, and at least the connecting portion inside a molded body is resin-sealed. 3. A water quality sensor comprising a working electrode provided with a sensor chip having an ion-sensitive field effect transistor and a reference electrode, wherein an electrode portion for external connection is provided inside a molded body forming the outer shape of the working electrode. And a flexible printed circuit board formed by including a wire bonding electrode portion for connecting the sensor chip and the sensor chip are arranged adjacent to each other, and the wire bonding electrode portion provided on the sensor chip and the wire bonding electrode of the flexible printed circuit board. The water quality sensor is characterized in that at least the connection portion inside the molded body is resin-sealed by connecting the portion with a wire. 4. A water quality sensor comprising a working electrode provided with a sensor chip having an ion-sensitive field effect transistor and a reference electrode, wherein an electrode part for external connection is provided inside a molded body forming the outer shape of the working electrode. And a wire bonding electrode portion for connecting the sensor chip, the conductive plate and the sensor chip are arranged adjacent to each other, and the wire bonding electrode portion provided on the sensor chip and the wire bonding electrode portion of the conductive plate are connected to each other. A water quality sensor characterized in that it is connected by a wire, and at least the connection portion inside the molded body is resin-sealed. 5. The water quality sensor according to claim 2, wherein the wire bonding electrode portion for connecting the sensor chip is provided at an end portion of the flexible printed circuit board. 6. A wire bonding electrode portion for connecting a sensor chip is provided at a position sandwiched by both ends of the flexible printed circuit board.
Water quality sensor described. 7. The flexible printed circuit board is insert-molded inside the molded body.
The water quality sensor according to any one of 5 and 6. 8. The water quality sensor according to claim 4, wherein a conductive plate is insert-molded inside the molded body.