JP3096087B2 - Ion sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor ion sensor for performing ion measurement and the like, and more particularly to a mounting structure of an ion sensor.

[0002]

2. Description of the Related Art Conventionally, mounting of an ion-sensitive field effect transistor (hereinafter referred to as ISFET) involves directly bonding a wire to an ISFET chip or attaching it to a flexible printed circuit (hereinafter referred to as FPCB). The first problem is the positioning of the electrode part during bonding. Since the ISFET is expected as a microsensor, the distance between the electrode portions is small, and alignment is difficult. The next problem is insulation sealing with a resin after bonding. In the past, the structure was not taken so as to be easily sealed, and was carefully performed manually one by one. Because of this IS
The assembling cost of the FET has increased, and an inexpensive ion sensor could not be supplied.

[0003]

The object of the present invention is to provide an ISFET that is easy to automate.
It is intended to provide a sealing technology and a structure of the above, improve the workability of the above-mentioned assembling process, and realize an inexpensive ion sensor.

FIGS. 1 (a) and 1 (b) are a plan view of a flexible printed circuit board (hereinafter referred to as "FPCB") used in the present invention and a sectional view taken along the line AA 'of FIG. 1 (a). The conductor foil 2 is formed inside by an insulating film such as the above, and the conductor foil 2 forms an electric wiring circuit.
An external (connector) connection terminal portion 3 connected to the conductor foil 2 and a sensor chip (ISFET) connection bump electrode portion 4 described later are formed. Reference numeral 5 denotes an ion sensitive window for exposing the sensitive portion of the sensor chip, and reference numeral 6 denotes a liquid junction hole forming a liquid junction. Reference numeral 7 denotes a heat-resistant reinforcing plate which is integrated with the insulating film 1 by bonding or the like. An opening 8 for attaching a sensor chip and a liquid junction hole 6 are provided at a portion facing the bump electrode portion 4 and the ion-sensitive window. Openings 9 are respectively formed in the opposed portions of. The opening 8 is formed larger than the shape of the sensor chip.

FIGS. 2 (a), 2 (b) and 2 (c) are assembly explanatory views of the present invention for mounting a sensor chip. Reference numeral 10 denotes a sensor chip in which a bonding bump electrode 10a and an ion sensitive portion 10b are formed in advance. I have. Then, as shown in FIG. 2A, the bump electrodes 4 and 10a are joined in the chip hole 8. Next, the sensor chip 10 is sealed with an insulating resin 11 so that the ion-sensitive portion 10b region is exposed and the opening 8 of the reinforcing plate 7 is filled. The sheet-like ion sensor can be realized by the structure shown in FIG. With such a configuration, since the reinforcing plate is attached to the FPCB when bonding the ISFET chip, the bonding position can be accurately adjusted. Further, by adjusting the size of the opening window of the reinforcing plate, the bonding position can be automatically adjusted just by inserting the ISFET into the window. Further, the resin 11 is also used for sealing the insulating resin to the chip.
By adjusting the viscosity of the resin, it is possible to seal automatically so that the ion-sensitive part is exposed by dropping a certain amount on the window. Next, as shown in FIG. 2 (c), a metal dummy electrode 14 is embedded in a case 13 filled with a saturated KCl gel 12, and the above-mentioned sheet-like sensor is integrally formed so that a liquid junction is in contact therewith.

FIG. 3 is a structural view of another embodiment of the present invention, showing an example in which a differential configuration is formed using two sheet-like sensors.
A structure in which sheets bonded with 0 and 10 'are bonded to each other, a liquid junction 9 is provided near the ISFET on the outwardly facing sheet, and a case is filled with a saturated KCl gel 12 and a metal pseudo electrode 14 is provided therein. And ISFET in contact with the saturated KCl gel in the case with this configuration
10 'functions as a reference ISFET, and the ISFET 10 facing the outside of the case detects the ion concentration of the solution to be measured. The two ISFETs are opposed to the metal pseudo electrode 14 in the saturated KCl gel, and can output a differential voltage as a result.

FIG. 4 is a structural view of another embodiment of the present invention, in which ISFETs 10 and 10 'are adhered to both surfaces of one substrate (sheet), in a direction in contact with a saturated KCl gel and in a direction in contact with a solution to be measured. Two ISFETs 10, 10 'are attached to a sheet-like bonding portion in opposite directions, respectively, and are attached to a case 13 with this configuration, a liquid junction 9 is provided, the inside of the case is filled with a saturated KCl gel 12, and a pseudo metal is formed. By providing the electrode 14, an ion sensor having a differential configuration can be easily manufactured. An ion-insensitive film such as a diamond-like thin film is formed in advance on the ion-sensitive portion 10b 'of the sensor chip 10', and functions as a reference or reference electrode.

[0008]

According to the present invention, ISFET bonding and resin encapsulation are facilitated and automation is possible with simple equipment, so that the assembly cost is greatly reduced and the effect of realizing an inexpensive ion sensor is great. .

[Brief description of the drawings]

FIG. 1 is a structural diagram of a flexible printed circuit board (FPCB) used in the present invention.

FIG. 2 is an explanatory view of the assembly of the present invention.

FIG. 3 is a structural view of another embodiment of the present invention.

FIG. 4 is a structural view of another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating film 2 Conductor foil 3 External connection electrode 4 Bump electrode 5 Ion sensitive window 6 Liquid junction hole 7 Reinforcement plate 8 Chip mounting opening 9 Liquid junction opening 10 Ion sensor chip 10a Bump electrode 10b Ion sensitive part 12 Saturated KCl gel 13 Case 14 Metal pseudo electrode

Claims (2)

(57) [Claims] 1. A flexible printed circuit board (hereinafter referred to as "FPCB") in which an electric wiring circuit made of a semiconductive foil is provided with an electrode portion for external connection and a bump electrode portion for sensor chip connection, and a liquid junction penetrating the FPCB. A hole and an ion-sensitive window are provided, and a reinforcing plate having an opening in a portion opposite to the electrode portion for connecting the sensor chip of the FPCB, the ion-sensitive window and the liquid junction hole is integrally formed with the FPCB,
The sensor chip was provided in one opening of the reinforcing plate, the bump electrode of the sensor chip was joined to the bump electrode for connection, and the sensor chip in the opening was resin-sealed and filled with saturated KCl gel. A metal pseudo electrode is embedded in the case, and the case and the ion sensor are saturated with KCl.
An ion sensor, wherein the gel and the opening for liquid junction or the ion sensitive window are integrally formed so as to be in contact with each other. 2. The ion sensor according to claim 1, wherein a plurality of bump electrodes for connecting sensor chips are provided on the FPCB.