JPH0732533U - Pressure sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] The gold wire and the lead wire are not directly connected to each other by soldering to simplify the connection work and prevent the decrease in reliability due to the occurrence of eutectic. [Structure] The sensor chip 23 is fixed to the recess 22a of the silicon pedestal 22. The output of the bridge circuit 25 formed in the diaphragm 23a portion of the sensor chip 23 is output via the electrodes 26a to 26e. The five lead wires 12a to 12e to be inserted into the catheter are formed by a conductor foil on each of the two laminated strip-shaped insulating films 27a and 27b. The electrodes 26a-26e of the sensor chip 23 are connected to the lead wires 12a-12.
Bonding pads 28a-2 formed at the tip of e
8e and gold wire 29a ~ 2 by a bonding device
9e is electrically connected by thermocompression bonding or the like. The connection work is simple and eutectic is not possible, so the reliability is improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pressure sensor in which a detection signal output from a sensor chip that detects pressure is taken out to the outside through a thin tube.

[0002]

[Prior art]

 Conventionally, as this type of pressure sensor, for example, there is one as shown in FIG. This has a structure in which a sensor chip is built in the tip of an elongated tubular measurement unit so that it can be inserted into the waist of the human body or the like to measure the local pressure inside the body.

That is, in FIG. 7, the semiconductor sensor chip 1 is formed with a diaphragm (not shown) that displaces in response to pressure, and its resistance value changes on the upper surface 1 a according to the amount of displacement of the diaphragm. A bridge circuit 2 that outputs an electric signal is formed. Five electrodes 3a to 3e are formed on the upper surface 1a of the semiconductor sensor chip 1 by an aluminum pattern, and the five output terminals of the bridge circuit 2 are led to the ends of the upper surface 1a.

The semiconductor sensor chip 1 is fixedly attached to a recess 4 a formed in a long silicon pedestal 4. The five lead wires 5a to 5e in a state where the copper wires are covered with an insulating material and bundled in a ribbon shape are for electrical connection with the electrodes 3a to 3e of the semiconductor sensor chip 1 and have a tip portion. Is obliquely cut to have an elliptical shape and is fixed to the upper surface 4b on one end side of the silicon pedestal 4 in a state where the conductor surface is exposed.

Gold wires 6a to 6e as bonding wires are electrically connected to each other via solder 7 at the tips of the five lead wires 5a to 5e. Each of the other ends is electrically connected to the corresponding one of the electrodes 3a or 3e of the semiconductor sensor chip 1 by thermocompression bonding.

As a result, the bridge circuit 2 of the semiconductor sensor chip 1 is electrically connected to the outside through the five lead wires 5a or 5e, and when the diaphragm of the semiconductor sensor chip 1 is displaced according to the pressure, the bridge circuit 2 is bridged. The resistance value of the circuit 2 changes, and the change can be taken out as an electric signal.

[0007]

[Problems to be solved by the device]

 However, the conventional structure as described above has the following problems. That is, in this type of small-sized pressure sensor, the diameter of the thin tube of the unit in which the pressure sensor is provided is, for example, about 1 mm, and the diameters of the signal lines 5a to 5e inserted through the inside are small in order to downsize the entire structure. Since the wire diameter of the gold wires 6a to 6e is about 100 μm and the wire diameter of the gold wires 6a to 6e is, for example, about 25 μm, it is extremely difficult to connect the gold wires 6a or 6e to the signal wires 5a to 5e by soldering. Since it is necessary to perform fine processing in a narrow range, workers are required to have highly accurate technology.

Further, since the gold wires 6a to 6e and the signal wires 5a to 5e are connected by soldering, the gold wires 6a to 6e and the solder generate a eutectic, so that the eutectic portion is large. If so, the gold wires 6a to 6e tend to melt into the solder due to aging and become brittle. Therefore, in order to suppress the occurrence of eutectic as much as possible, it is necessary to quickly perform the soldering work.

Therefore, in the prior art, when connecting between the gold wires 6a to 6e and the lead wires 5a to 5e, a very advanced technique is required in the soldering work, and Since eutectic of gold and solder occurs in the soldered part, there is a problem that reliability cannot be secured.

The present invention has been made in view of the above circumstances, and an object thereof is to facilitate the work of connecting a lead wire and a bonding wire to reduce the number of steps, and to eliminate the occurrence of eutectic to improve the reliability. It is to provide a pressure sensor capable of improving the above.

[0011]

[Means for Solving the Problems]

 The pressure sensor of the present invention comprises a thin tube to be inserted into a measurement target region, a connecting member formed in a state in which two or more strip-shaped insulating films each having a plurality of conductor foils inserted into the thin tube are laminated, and A sensor chip that is provided inside the tip of the thin tube and converts the pressure received by the diaphragm into an electric signal according to the amount of displacement and outputs the electric signal through a plurality of electrodes, and each electrode of this sensor chip and the conductor foil of the connecting member. It is characterized in that it is provided with a bonding wire for electrically connecting it to the tip of the.

[0012]

[Action]

 According to the pressure sensor of the present invention, the connecting member for connecting to the plurality of output terminals of the sensor chip is formed by laminating two or more strip-shaped insulating films each having a plurality of conductor foils formed in a predetermined width. Since the sensor chip outputs the detection signal by inserting it into the narrow tube, even if one strip-shaped insulating film cannot form a sufficient number of conductor foils connected to each output terminal of the sensor chip. , It is possible to configure so as to correspond, and by this, it becomes possible to electrically connect the lead wire and each electrode of the sensor chip by a bonding wire, so that the connection work can be performed. In addition to being simple, the occurrence of eutectic crystals can be eliminated and reliability can be improved.

[0013]

【Example】

 An embodiment in which the present invention is applied to a small-sized medical pressure sensor will be described below with reference to FIGS. In FIG. 2 showing the overall configuration, a catheter 11 as a thin tube is made of, for example, tephron and has a tubular shape with a diameter of about 1 mm, and its distal end portion is easily inserted into a sheath (outer cylinder) not shown. It is formed as a truncated cone portion 11b, and a connecting member 13 having lead wires 12a to 12e formed of five conductor foils is inserted therein (see FIG. 3). A window 11a for pressure detection is formed at the tip of the catheter 11, and the base end is fixed to the grip 14. Inside the grip 14, there is provided a printed circuit board 20 on which four resistors 16 to 19 constituting a compensation circuit 15 are arranged (see FIG. 4).

FIG. 3 shows an enlarged cross section of the distal end portion of the catheter 11, and a pressure detection portion 21 is provided inside the catheter 11. The silicon pedestal 22 is fixed to the inner wall of the catheter 11, and a recess 22a is formed on the upper surface side, and the sensor chip 23 is adhesively fixed to the recess 22a. Further, a hole portion 22b is formed on the rear surface side corresponding to the recess 22a so as to penetrate from the upper surface side. The pressure detecting portion 21 is filled with a deformable resin 24 such as a silicone resin on the surface portion thereof so that the diaphragm 23a of the sensor chip 23 does not come into direct contact with the outside air, and the window portion 11a of the caterel 11 is exposed from the outside. The pressure applied to the inside via the resin 24 is received.

In FIG. 1 showing the portion of the pressure detecting portion 21, a bridge circuit 25 of a well-known structure formed so as to bridge-connect four diffusion piezoresistors is integrally formed on the diaphragm 23a of the sensor chip 23. (See FIG. 6), and the five output terminals are led out by five electrodes 26a to 26e formed by an aluminum pattern on the upper surface. Then, pad portions for bonding are formed at the tips of the electrodes 26a to 26e, and the pad portions are provided at different positions as shown in the figure.

The lead wires 12a to 12e described above are configured as follows. Two strip-shaped insulating films 27a and 27b are inserted in the catheter 11 in a superposed state, and lead wires 12a, which are two conductor foils having a predetermined width, are formed on the strip-shaped insulating film 27a. 12b is provided, and lead wires 12c, 12d, 12e are provided as three conductor foils of a predetermined width formed on the band-shaped insulating film 27b (see FIGS. 1 and 3).

In this case, the two strip-shaped insulating films 27a and 27b are made of, for example, a polyimide resin, and for example, those used in a bonding technique called TAB (Tape Automated Bonding) are used. The strip-shaped insulating films 27a and 27b have a thickness of about 50 μm and a width of about 0.5 mm, and the conductor foils forming the lead wires 12a to 12e are formed of copper foil with a thickness of about 35 μm. I did it. Since about three lead wires can be formed on the band-shaped insulating film having a width that can be inserted into the catheter 11, in order to allow the five lead wires 12a to 12e to be inserted into the catheter 11, The strip-shaped insulating films 27a and 27b may be stacked in two layers.

Further, on the tip portions of the strip-shaped insulating films 27a and 27b, that is, on the sensor chip 23 side, bonding pads 28a to 28b are formed in which the tip portions of the lead wires 12a to 12e are formed wider than the line width. . The tip ends of the band-shaped insulating films 27a and 27b are adhered to the connecting portion 22c formed on one end side of the silicon pedestal 22, and the bonding pads 28a to 28e are respectively used as bonding wires. The gold wires 29a to 29e each having a wire diameter of about 25 μm are connected to the electrodes 26a to 26e of the sensor chip 23 by a thermocompression bonder or the like. The bonding portion including the gold wires 29a to 29e is coated with the resin 30.

On the other hand, on the base end side of the strip-shaped insulating films 27a and 27b, that is, on the grip 14 side, the portions 31a and 31b led out from the catheter 11 are formed wide and the lead wires 12a to 12e. The conductors forming are also formed as wide connection portions 32a to 32e. Further, the lead wires 12a to 12e are extended so as to project in a bare state from each of the strip-shaped insulating films 27a and 27b. As shown in FIG. 5, the connection portions 32a to 32e of the lead wires 12a to 12e are electrically connected to the terminal pattern portions formed at the corresponding positions of the printed circuit board 20 by soldering.

FIG. 6 shows an electrical equivalent circuit in a state in which the sensor chip 23 and lead wires 12a to 12e are connected to the compensation circuit 15 of the printed circuit board 20, which is formed on the diaphragm 23a of the sensor chip 23. The four resistors R1, R2, R3, and R4 are bridge-connected, and their output terminals are connected to the respective resistors 16 to 19 of the compensation circuit 15 via lead wires 12a to 12e as shown in the figure. Five output terminals P1 to P5 including the ground line are led to the connector 33 (see FIGS. 2 and 4).

According to the above configuration, when the sheath (outer cylinder) for inserting the pressure sensor is inserted into the affected part of the human body and the catheter 11 is inserted into the affected part through the sheath, the distal end part thereof is inserted. The diaphragm 23a of the sensor chip 23 is displaced through the resin 24 by the pressure exerted on the window portion 11a. When the diaphragm 23a is displaced, the resistance value of the resistor of the bridge circuit 25 is changed by the piezoelectric effect by an amount corresponding to the pressure.

At this time, a bias voltage is applied to the bridge circuit 25 from the outside through the connector 33 of the grip 14 from the lead wires 12a to 12e, and the change in the resistance value is output as an electric signal. The electric signal can be taken out as a pressure detection signal again through the lead wires 12a or 12e and the compensation circuit 15 arranged on the printed circuit board 20.

According to this embodiment, the conductor wires formed on each of the strip-shaped insulating films 27a and 27b are five lead wires 12a to 12e, and the strip-shaped insulating films 27a and 27b are stacked in two stages. Since it is configured to be inserted into the catheter 11 in this state, even if the one strip-shaped insulating film cannot be inserted into the catheter 11 due to its width when forming the five lead wires 12a to 12e. This allows the pressure sensing portion 21 side to be electrically bonded by thermocompression bonding between the electrodes 26a to 26e of the sensor chip 23 with gold wires 22a to 22e between the electrodes 26a to 26e. Since it becomes possible to connect, it is possible to eliminate the need for fine and skilled connection work due to soldering as in the past. In addition, the connection work becomes easy and the number of steps can be reduced, and since no solder is used, the occurrence of a eutectic between the gold wire and the solder can be eliminated and the reliability can be improved.

[0024]

[Effect of device]

 As described above, according to the pressure sensor of the present invention, the lead wires connected to the plurality of output terminals of the sensor chip are formed by laminating two or more strip-shaped insulating films each having a plurality of conductor wires of a predetermined width. Since the lead wire is inserted into the thin tube and the detection signal from the sensor chip is output to the outside, the number of conductor wires connected to each output terminal of the sensor chip is one. Even if the number is small, it is possible to cope with it. Further, since the lead wire and each electrode of the sensor chip can be electrically connected by a bonding wire, the connection work is simplified and the eutectic crystal is formed. This has the excellent effect of improving reliability by eliminating the occurrence of

[Brief description of drawings]

FIG. 1 is an external perspective view of an essential part showing an embodiment of the present invention.

FIG. 2 is a side view of the overall configuration.

FIG. 3 is a vertical sectional side view of the tip portion.

FIG. 4 is a plan view of a compensation circuit portion.

[Fig. 5] Side view of the same section

FIG. 6 is an electrical equivalent circuit diagram.

FIG. 7 is a view corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

11 is a catheter (capillary tube), 12a to 12e are lead wires (conductor foil), 13 is a connecting member, 14 is a grip, 15 is a compensation circuit, 16 to 19 are resistors, 20 is a printed circuit board, 2
1 is a pressure detection part, 22 is a silicon pedestal, 23 is a sensor chip, 24 is a resin, 25 is a bridge circuit, and 26a to 26a.
e is an electrode, 27a and 27b are strip-shaped insulating films, 28a
28e are bonding pads, 29a to 29e are gold wires (bonding wires), and 32a to 32e are connecting portions.

Claims (1)

[Scope of utility model registration request] 1. A thin tube to be inserted into a measurement target region, a connecting member formed by stacking two or more strip-shaped insulating films that are inserted into the thin tube and have a plurality of conductor foils formed thereon, and a tip of the thin tube. A sensor chip that is provided inside to convert the pressure received by the diaphragm into an electric signal corresponding to the amount of displacement and output the electric signal via a plurality of electrodes; and each electrode of the sensor chip and the tip of the conductor foil of the connecting member. A pressure sensor comprising a bonding wire for electrically connecting the two.