JP3768611B2 - Sensor structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention particularly relates to a sensor structure having an improved signal extraction site such as a magnetic sensor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a signal extraction structure such as a magnetic sensor as shown in FIG. 2 or FIG. 3 is known.
[0003]
In the case of FIG. 2, a thin pedestal 5 is disposed on the upper surface of the hollow portion 4 of the mount substrate 3, and a magnet 6 for applying a bias magnetic field is provided on the pedestal 5. In the hollow portion 4, a magnetic sensor chip 8 is disposed via a pedestal 7 joined to the pedestal 5, and the chip 8 and the electrodes of the mount substrate 3 are connected via a number of wires 9. In this case, the wire 9 is soldered by connecting a minute solder ball melt-bonded to the electrode of the chip 8 and the pad of the mount substrate 3. Reference numeral 10 denotes a lead wire.
[0004]
Then, the sensor housing 1 is attached to the measurement site via the spacer 2 so as to maintain a minute (for example, 0.1 mm) gap between the sensor housing 1 and the chip 8 from the inside. In order to absorb various errors, spacers 2 of different sizes are attached individually.
[0005]
In the case of FIG. 3, solder coating is applied to the electrode of the chip 8 having the magnet 6 attached to the upper surface, and the electrode at one end of the flexible wiring board 13 is connected thereto by solder bonding. Then, the chip 8 is bonded via a double-sided tape (or insulating sheet) 12 located at the measurement site of the sensor housing 1. The double-sided tape 12 also has a function of maintaining a minute distance between the sensor chip 8 and the sensor housing 1.
[0006]
[Problems to be solved by the invention]
However, in the signal extraction structure shown in FIG. 2, work is very complicated because minute solder bumps are attached to many electrodes of the chip 8, and the wires 9 are soldered one by one by a minute welding machine. In addition, since the chip 8 is attached to the sensor housing 1, it is necessary to prevent the wire joint portion from being in electrical contact with the sensor housing 1 and to be attached at the smallest possible interval. There is a problem that the height of each unit must be measured and mounting is performed using the spacer 2 having a thickness suitable for this, which requires a large number of work steps and high production costs.
[0007]
Further, in the signal extraction structure of FIG. 3, it is difficult to align the flexible wiring board 13 and the chip 8, and the flexible wiring board 13 is bent near the joint, but the reliability of the joint strength at this time is lowered. There is. In addition, the adhesive strength of the double-sided tape 12 is relatively small, and there is a problem that the chip 8 is displaced with long-term use.
[0008]
The present invention has been proposed to solve such a problem, eliminates the complexity of electrode bonding to the chip, has high electrical insulation with respect to the sensor housing, and sufficiently secures the electrode bonding strength. An object is to provide a highly reliable sensor structure.
[0009]
[Means for Solving the Problems]
The present invention arranges a flexible wiring board so as to cover the entire area of the sensor chip surface, solders the flexible wiring board and the electrode portion of the chip to each other, and covers the back surface covering the entire chip area of the flexible wiring board. It adhere | attaches via the adhesive agent with respect to the measurement part of a sensor housing.
[0010]
[Operation and effect of the invention]
Since all the electrode portions of the chip and the flexible wiring board are positioned and solder-bonded by a single alignment, the number of man-hours for electrode bonding is greatly reduced and the workability is improved. In addition, since the flexible wiring board that covers the entire area of the chip surface is directly bonded to the sensor housing, even if the signal extraction part of the flexible wiring board is bent, the electrode joint is not connected between the chip and the sensor housing. Since it is completely sandwiched between them, its bonding strength does not decrease, it exhibits high durability, and it can maintain good electrical insulation against the chip, and these together provide sufficient sensor reliability Sex is secured.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, a chip 8 having a magnet 6 attached to one surface is solder-bonded to a flexible wiring board 13 disposed so as to cover the entire front side where the sensor pattern of the chip 8 is disposed.
[0012]
In this case, the electrodes of the chip 8 are soldered to electrode pads provided on the mounting surface of the chip 8 of the flexible wiring board 13 so as to correspond to the electrode portions 8A of the chip 8, and the chip 8 is fixed. As a solder bonding method, solder bumps are provided on the chip 8 or solder is plated on the electrode pads of the flexible wiring board, and at the time of bonding, thermocompression bonding is performed with a fine iron, or melting is performed in a constant temperature bath. There are methods.
[0013]
A portion 13A that covers the entire front side of the chip 8 of the flexible wiring board 13 is adhered to the inside of the measurement site of the sensor housing 1 with an adhesive, whereby the thickness of the flexible wiring board 13 functions as a spacer. In addition, insulation between the chip 8 and the sensor housing 1 is also ensured.
[0014]
In this manner, since the chip 8 is bonded to the pad provided at the portion corresponding to the extraction electrode of the chip 8 of the flexible wiring board 13 with the solder, the bonding of all the electrodes is performed by one alignment. The position is determined, and a lot of wire handling and alignment are not required, greatly reducing the number of manufacturing steps.
[0015]
In addition, since the entire area of the surface of the chip 8 is covered with the flexible wiring board 13 and the flexible wiring board 13 in this portion is used as a spacer and is directly bonded to the sensor housing 1, the signal of the flexible wiring board 13 is used. Even if the lead-out portion is bent, the electrode joint portion is completely sandwiched between the chip 8 and the sensor housing 1, so that the joint strength does not decrease, and the chip 8 can be provided without any trouble. The electrical insulation between the sensor housing 1 and the sensor housing 1 is also reliably maintained.
[0016]
Since the flexible wiring board 13 is firmly bonded to the measurement site of the sensor housing 1 by an adhesive over a region corresponding to at least the surface area of the chip 8, the flexible wiring board 13 is high without causing misalignment even for long-term use. Maintain mounting durability.
[Brief description of the drawings]
FIG. 1 is an enlarged sectional view schematically showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a conventional example.
FIG. 3 is a cross-sectional view of another conventional example.
[Explanation of symbols]
1 Sensor housing 6 Magnet 8 Chip 13 Flexible wiring board

Claims (1)

A flexible wiring board is arranged so as to cover the entire surface of the sensor chip, the flexible wiring board and the electrode part of the chip are soldered together, and the back surface covering the entire chip area of the flexible wiring board is measured on the sensor housing. A sensor structure, wherein the sensor structure is bonded to a part via an adhesive.

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