JPH073373B2 - Method of manufacturing distributed pressure sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a distributed pressure sensor, and more specifically, a plurality of sensor cells mounted on a robot hand for detecting a force received from a grasped object are arranged in a matrix. Arranged,
The present invention relates to a method for manufacturing a distributed pressure sensor in which a flexible printed wiring board is finely soldered to these sensor cells.

[Conventional technology]

Conventional robots are often driven by sequence control or open-loop control, and work is performed in a specific limited environment. Therefore, the work content and the ability of the robot are limited. For example, in the case of a pick-and-place robot, parts are mounted in a flow work, and it is limited to a series of specific works such as gripping a specific part, and the function of selecting and gripping different kinds of parts is not available. I don't have it.

However, recently, as robots have become more intelligent, visual sensors and pressure sensors corresponding to human sense have been developed, and robots that can operate in various environments are being put to practical use. There is a distributed pressure sensor as each pressure sensor for such an intelligent robot, but when such a sensor is attached to a robot hand or the like and the robot hand grips an object, the output obtained from the sensor is detected and feedback control is performed. By doing so, the gripping force of the object can be controlled and the hardness can be recognized.

FIG. 4 shows an example of a conventional distributed pressure sensor. In this example, fine conductive rubber strips 101 and 102 intersecting at right angles to each other are combined in two layers, and when a force in the vertical direction is applied to the rubber strip array surface, the contact portions of the rubber strips 101 and 102 contact each other. Since the area increases and the resistance changes, this is detected to know the magnitude of the applied force.
However, with such a distributed pressure sensor, an output proportional to the applied force cannot be obtained, and the output becomes non-linear,
Further, there is a drawback that it is not suitable for detecting the distribution of force with high density.

Therefore, in order to solve such a drawback, a distributed pressure sensor as shown in FIGS. 5 to 8 has been proposed.

In FIGS. 5 and 6, 1 is a sensor cell, 2 is a pressure-receiving portion mounted on the sensor cell 1, and 3A to 3D are arranged around the pressure-receiving portion 2 on the sensor cell 1 to detect strain generated in the sensor cell 1. A semiconductor strain gauge, 4A is an electrode of a solder bump which is also arranged on the sensor cell 1, 5 is an elastic floor which holds the sensor cell 1 and acts as an elastic body, and 6 is a solder bump which is arranged on the sensor cell 1. The flexible printed wiring board is electrically connected to the electrode 4A. Here, the semiconductor strain gauges 3A to 3D are incorporated in the Wheatstone bridge circuit as shown in FIG. 7, and the resistance change in the semiconductor strain gauges 3A to 3D is added to the sensor cell 1 by taking out from terminals at diagonal positions. Force is detected as the strain value, power supply to the bridge circuit and semiconductor strain gauge 3A
Output signals from 3D can be taken out to the outside through the electrode 4A and the flexible printed wiring board 6.

Therefore, in the manufacturing process of such a distributed pressure sensor, when fine soldering is performed between the sensor cell 1 and the flexible printed wiring board 6, in the conventional case, as shown in FIG. The flexible printed wiring board 6 is placed on the frame 7 having a hole into which the portion 2 can be inserted, the sensor cell 1 is placed upside down, and the pressure receiving portion 2 is placed in the through hole 6A of the flexible printed wiring board 6.
Laser light is irradiated from the back side of the upper sensor cell 1 fitted in the above to melt the solder bumps of the electrodes 4A and weld them to the solder lands 4 on the flexible printed wiring board 6 to obtain an electrical connection.

[Problems to be Solved by the Invention]

However, in the above-described conventional method for manufacturing the distributed pressure sensor, when soldering is performed, as shown in FIG.
When the sensor cell 1 is locally heated, the side opposite to the soldered side of the sensor cell 1 jumps up, and the sensor cell 1 is connected while being inclined (also called tombstone). By the way, originally, the sensor cell 1 and the flexible printed wiring board 6 must be connected in parallel, and the detection function is impaired in the above-mentioned connected state. Further, as shown in FIG. 10, the solder land 4 of the flexible printed wiring board 6 is
When the sensor cell 1 is displaced and placed on the solder land 4
The sensor cells 1 are connected at an angle of θ degrees with respect to the arrangement direction.

An object of the present invention is to solve the above-mentioned conventional problems,
It is an object of the present invention to propose a method of manufacturing a distributed pressure sensor that has a highly reliable electrical connection between electrodes of a plurality of sensor cells and a solder land of a flexible printed wiring board in a correct posture and with durability.

[Means for Solving the Problems]

In order to achieve such an object, the present invention has a semiconductor strain gauge for detecting strain and an electrode of a solder bump, and a sensor cell provided with a pressure receiving portion for receiving a load is provided in a matrix, and the electrode is provided as an electrode. In manufacturing a distributed pressure sensor in which a flexible printed wiring board in which a conductor pattern electrically connected and a through hole penetrating a pressure receiving portion are formed is provided on a sensor cell, the shape of the flexible printed wiring board was adjusted to match. A positioning member having a concave portion and a plurality of sensor cell positioning holes in which the pressure receiving portion can be fitted in the concave portion, and a cutout window corresponding to the shape of the flexible printed wiring board, are cut out around the flexible printed wiring board. The flexible printed wiring board is fixed by the fixing frame that can be held around the window, and the pressure receiving part of each sensor cell is positioned. The electrode is positioned so as to keep contact with the conductor pattern by fitting in the sensor cell positioning hole of the member, and the glass plate is placed on the cutout window to be formed between the glass plate and the flexible printed wiring board. Each sensor cell is held in the space of the cutout window, and the sensor cell and the flexible printed wiring board are heated through the glass plate to solder-connect the electrode solder bumps to the conductor pattern. .

[Action]

According to the present invention, the flexible printed wiring board is fixedly held between the positioning member for positioning the flexible printed wiring board and the fixed frame having the cutout window, and the through hole of the held flexible printed wiring board is formed. The pressure receiving portion of each sensor cell is fitted into the sensor cell positioning hole of the positioning member via the positioning member for positioning, and in this state, the electrode of each sensor cell is kept in contact with the conductor pattern of the flexible printed wiring board. A glass plate is placed on the glass plate, which is heated from above the glass plate so that soldering is performed between the electrode and the conductor pattern.The sensor cell is held in the space of the cutout window.
Even when locally heated, the glass plate prevents the jumping up, and the tombstone does not occur. Therefore, a stable and reliable electrical connection state can always be obtained.

〔Example〕

Hereinafter, the present invention will be described in detail and specifically with reference to the drawings. FIG. 1 shows an example of a jig for carrying out the present invention. Here, reference numeral 21 is a positioning member for positioning and holding the flexible printed wiring board 6, and a concave portion having a shape matching the outer periphery of the flexible printed wiring board 6.
22 and screw holes 23 and the through holes 6A provided in the flexible printed wiring board 6 are provided at the same intervals.
There is a sensor cell positioning hole 24 into which the pressure receiving portion of the sensor cell can be inserted, and the depth of the recess 22 is made slightly shallower than the plate thickness of the flexible printed wiring board 6. Further, one flexible printed wiring board 6 is provided with a conductor pattern, a solder land 4, and the above-mentioned through hole 6A for projecting the pressure receiving portion 2 of the sensor cell 1 (second).
See figure).

31 is a positioning member for the flexible printed wiring board 6
The fixed frame 31 has a similar shape slightly smaller than the outer circumference of the flexible printed wiring board 6 and has a cutout window 32 for penetrating the laser beam downward. It has a recess 33 and a fixing hole 34 into which the glass plate 9 can be fitted into the fixing frame 31 from above the cutout window 32.

Therefore, the sensor cell 1 and the flexible printed wiring board 6 are combined by the jig as described above so that electrical connection can be obtained. First, as shown in FIG. The flexible printed wiring board 6 is placed so as to be fitted, and the through hole 6A of the flexible printed wiring board 6 is attached to the sensor cell positioning hole.
Align the fixing hole 34 with the screw hole of the positioning member 21 while aligning with 24.
The fixed frame 31 is aligned with the fixed frame 31, and the flexible printed wiring board 6 is held and fixed between the fixed frame 31 and the positioning member 21 by the overlapping bolt 35.

Next, after applying a surface active agent to each of the solder lands 4 of the flexible printed wiring board 6, the pressure receiving portion 2 of the sensor cell 1 is attached to the through hole 6A of the flexible printed wiring board 6.
Then, the electrode 4A of the solder bump on the sensor cell 1 and the solder land 4 are kept in contact with each other. Then, in this state, the glass plate 9 is placed in the recess 33 on the upper surface of the fixed frame 31. At this time, a slight margin is kept between the sensor cell 1 and the glass plate 9, but the flexible printed wiring board 6 and the sensor cell 1 may be kept at least to an allowable degree of parallelism. desirable. When the sensor cell 1 and the glass plate 9 are in contact with each other, there is a risk that the sensor cell 1 is pressed by the glass plate and the sensor cell is damaged, or the electrode 4A of the solder bump is crushed by the pressure and a bridge is formed in the solder. However, in the present embodiment, since a slight gap is provided between the sensor cell 1 and the glass plate 9 as described above, such a problem does not occur.

By locally heating or entirely heating the sensor cell 1 and the flexible printed wiring board 6 from above the glass plate 9 of the jig set in this way, the electrode 4A of the solder bump is melted and the solder land 4 is formed. It can be electrically connected. FIG. 3 shows a state of the distributed pressure sensor in which a plurality of fine soldering operations can be carried out between the individual sensor cells 1 and the flexible printed wiring board 6 according to the present invention in the correct posture as described above.

〔The invention's effect〕

As described above, according to the present invention, a positioning member having a plurality of sensor cell positioning holes, into which the pressure receiving portions of the sensor cells can be fitted, respectively, in a concave portion matching the shape of the flexible printed wiring board, and the flexible printed wiring board. With a cutout window corresponding to the shape of the flexible printed wiring board and a fixed frame that can hold the periphery of the flexible printed wiring board, the flexible printed wiring board is held between them, and The sensor cell of the positioning member is fitted in the positioning hole so that the electrode of the sensor cell is positioned so as to maintain contact with the conductor pattern of the flexible printed wiring board. So that it is held and heated through the glass plate, Since so soldering is performed between, by heating the flexible printed circuit board and the sensor cell while maintaining the normal posture is performed,
Tombstones do not occur and fine soldering with good soldering property and high reliability can be performed.

[Brief description of drawings]

1 is an exploded perspective view showing a jig for carrying out the present invention, FIG. 2 is a sectional view showing a process of an embodiment of the present invention, and FIG. 3 is a distributed pressure sensor according to the present invention. FIG. 4 is a cross-sectional view showing the structure, FIG. 4 is a perspective view showing the structure of a conventional distributed pressure sensor, FIG. 5 is a plan view of a sensor cell to which the present invention is applicable, and FIG. 6 is applicable to the present invention. FIG. 7 is a sectional view of a pressure sensor, FIG. 7 is a configuration diagram of a bridge circuit formed between semiconductor strain gauges on a sensor cell, FIG. 8 is a sectional view of a conventional soldering method, and FIG. 9 is a defective state of a conventional example. FIG. 10 is a cross-sectional view and FIG. 10 is a plan view showing another defect state of the conventional example. 1: Sensor cell, 2: Pressure receiving part, 4: Solder land, 4A: Electrode,
6: Flexible printed wiring board, 6A: Through hole, 9: Glass plate, 21: Positioning member, 22: Recessed part, 23: Screw hole, 24: Sensor cell positioning hole, 31: Fixed frame, 32: Cutout window, 33: Recessed part , 3
4: Fixed hole.

Claims (1)

[Claims] 1. A sensor cell having a semiconductor strain gauge for detecting strain and an electrode of a solder bump, in which a pressure receiving portion for receiving a load is provided in a projecting manner, is arranged in a matrix and electrically connected to the electrode. In manufacturing a distributed pressure sensor in which a flexible printed wiring board having a conductor pattern and a through hole penetrating the pressure receiving portion is provided on the sensor cell, a concave portion that matches the shape of the flexible printed wiring board is formed. A positioning member having a plurality of sensor cell positioning holes capable of fitting the pressure receiving portion in the recess, and a cutout window corresponding to the shape of the flexible printed wiring board, and the periphery of the flexible printed wiring board. The flexible printed wiring board is fixed by a fixing frame capable of holding around the cutout window, The pressure receiving portion of the positioning member by fitting it into the sensor cell positioning hole of the positioning member so that the electrodes are kept in contact with the conductor patterns respectively, and a glass plate is placed on the cutout window and The individual sensor cells are held in the space of the cutout window formed between the flexible printed wiring board and the flexible printed wiring board, and the electrodes are heated by heating the sensor cells and the flexible printed wiring board through the glass plate. A method for manufacturing a distributed pressure sensor, wherein the solder bumps of 1 are soldered to the conductor pattern.