JPH0663885B2 - 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, it has a columnar pressure-receiving portion for receiving a vertical load, and a single crystal via the pressure-receiving portion. The present invention relates to a method for manufacturing a distributed pressure sensor in which a plurality of detection elements capable of detecting a load applied to a silicon plate are arranged in a matrix and a flexible printed wiring board is provided for the plurality of detection elements.

[Prior Art] Conventional robots are often driven by sequence control or open-loop control, and work is performed in a specific limited environment. Therefore, there is a limit to the work content and the ability as a robot. It was 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 operations such as gripping specific parts, and there is no function to select and grip different types of parts. I haven't.

However, recently, with the advancement of intelligent robots, visual sensors and pressure sensors equivalent to human sense have been developed,
Robots that can operate in various environments are becoming practical. There is a distributed pressure sensor as a pressure sensor for such an intelligent robot. Such a sensor is attached to a robot hand or the like, and when the robot hand grips an object, the output obtained from the sensor is detected and feedback control is performed. By controlling the gripping force of the object,
The hardness can be recognized.

Therefore, the functions required for such a sensor are high sensitivity, high distribution density, uniform sensor characteristics, high reliability and durability, and low nonlinearity and hysteresis. It is small, lightweight and inexpensive.

FIG. 5 shows an example of a conventional distributed pressure sensor, and this example is a thin conductive rubber system 100 and 200 which intersect each other at right angles.
The strength of the applied force is detected by detecting that the area of the contact area of the rubber strip increases and the resistance changes in response to the force applied in the direction perpendicular to the rubber strip array surface. I tried to know that. However, in such a distributed pressure sensor, an output proportional to the applied force cannot be obtained, the output becomes non-linear, and it is not suitable for detecting the force distribution with high density.

Further, FIG. 6 shows another conventional example in which the Hall element 400 attached to the head 300 is opposed to the magnet 500, and when the vertical force is applied to the head 300, the Hall element 400 resists the spring force of the spring 600. The displacement is performed, and the change in the magnetic flux density in the Hall element portion is detected by the Hall element 400 to know the magnitude of the applied force.

However, such a pressure sensor has a drawback that the output sensitivity is different depending on whether the object to be grasped is a magnetic substance or a non-magnetic substance because the structure is complicated and the miniaturization is difficult. .

Therefore, in order to solve the above-mentioned drawbacks, the present applicant previously proposed a distributed pressure sensor as shown in FIGS. 7 to 9.

In FIGS. 7 and 8, 10 is a sensor cell of a detection element, 11 is a columnar pressure-receiving member (hereinafter referred to as a mesa) attached to a joint 12 on the sensor cell 10 using an adhesive, 13A.
13D is a semiconductor strain gauge that is arranged around the mesa 11 on the sensor cell 10 to detect strain generated in the sensor cell 10, 14 is an electrode of a solder bump that is also arranged on the sensor cell 10, and 15 is a sensor cell. An elastic floor that holds 10, acts as an elastic body, 16 is placed on the sensor cell 10,
The flexible printed wiring board (hereinafter referred to as FPC) is electrically connected to the electrodes 14.

Here, the semiconductor strain gauges 13A to 13D are incorporated in a Wheatstone bridge circuit as shown in FIG.
By extracting the resistance change in the semiconductor strain gauges 13A to 13D from the terminals at diagonal positions, the force applied to the sensor cell 10 is detected as the value of strain, thus supplying power to the bridge circuit and the semiconductor strain gauge 13
Output signals from A to 13D can be taken out through the electrode 14 and the FPC 16.

By the way, when manufacturing such a distributed pressure sensor, in the conventional case, as shown in FIG.
A frame 22 having a cell holding hole 21 formed thereon is placed, and after the sensor cell 10 is fitted into the cell holding hole 21, an adhesive agent is applied to the mesa joint 12 or the mesa 11 on the sensor cell 10.
Apply 23. Then, while holding the mesa 11 by the pickup 24, the mesa 11 is fixed on the joining portion 12 of the mesa and the adhesive 23
Then, the detecting element 25 is formed by curing the resin, and thereafter, the detecting element 25 is vertically mounted in the mesa through hole 26 formed in the FPC 16 as shown in FIG.
Thus, the laser beam 27 is radiated from the back surface side of the sensor cell 10, and the solder bump of the electrode 14 and the conductor pattern on the FPC 16 are irradiated.
28 was welded to obtain an electrical connection.

[Problems to be Solved by the Invention] However, in the above-described conventional manufacturing method, the mesa 11 is inclined as shown in FIG. 12, and further, the electric connection portion 30 between the FPC 16 and the sensor cell 10 and the adhesive 23 are formed. Deterioration may occur, impairing the high reliability and durability of the pressure sensor. Further, it is sufficient that the mesa 11 is fixed to the normal position on the sensor cell 10 as shown in FIG. 13A, but if the mesa 11 is fixed while being displaced as shown in FIGS. 13B and 13C, as shown in FIG. The sensitivity varies as shown in FIGS. 13A and 13B, and the sensitivity decreases as shown by b and c in FIGS. 13B and 13C. Therefore, there is a problem in signal processing of the output from the distributed pressure sensor.

Further, when the layer thickness of the adhesive 23 at the joint 12 between the mesa 11 and the sensor cell 10 is different as shown in FIGS. 15A and 15B, the hysteresis is different as shown in FIGS. 16A and 16B, respectively. This has caused a problem that the characteristics of a plurality of pressure sensors are not constant.

It is an object of the present invention that all of the plurality of detection elements that make up the distributed pressure sensor have uniform characteristics and have high reliability.
It is to propose a method of manufacturing a distributed pressure sensor having excellent durability.

[Means for Solving the Problems] In order to achieve such an object, the present invention has a semiconductor strain cage for detecting strain and electrodes of solder bumps, and a pressure receiving portion for receiving a vertical load is provided in a protruding manner. A single-crystal silicon cell is arranged in a matrix on an elastic floor, and a flexible printed wiring board having a conductor pattern electrically connected to an electrode and a through hole for penetrating a pressure receiving portion is provided on the single-crystal silicon cell. In manufacturing the distributed pressure sensor, the first positioning member having a plurality of first positioning holes capable of individually positioning the single crystal silicon cell, and the plurality of second positioning capable of individually positioning the pressure receiving portion. The first positioning member and the second positioning member are arranged so that the first positioning member and the second positioning member face each other in a state of being overlapped with the second positioning member having the hole. The flexible printed wiring board has a second through hole between it and the positioning member.
The electrode and the conductor pattern are welded while the electrode is kept in contact with the conductor pattern by fitting the single crystal silicon cell in the first positioning hole by fitting the electrode and the conductor pattern so that they are held so as to coincide with the positioning hole. The pressure receiving portion is fitted into the second positioning hole so that the pressure receiving portion can be bonded to the single crystal silicon cell, and the pressure receiving portion is bonded to the single crystal silicon by applying uniform pressure from the plurality of pressure receiving portions. It is a thing.

[Operation] According to the present invention, the flexible printed wiring board is first held in a positioned state between the first positioning member and the second positioning member, and then the single crystal silicon cell is fitted into the first positioning hole. By doing so, the relative position between the individual single crystal silicon and the flexible printed wiring board is positioned, and in this state, the electrodes and the conductor pattern are welded by laser light or the like so that electrical connection can be obtained. After that, the pressure-receiving portions are fitted into the second positioning holes in a state in which they can be bonded to keep contact with the single crystal silicon cells, and uniform pressure is applied from above these pressure-receiving portions to wait for the adhesive to cure. As a result, the bonding position between the pressure receiving portion and the single crystal silicon cell can be maintained accurately, and the occurrence of variations in the output characteristics from each detection element can be suppressed. be able to.

Embodiments Embodiments of the present invention will be described in detail and specifically below with reference to the drawings.

FIG. 1 shows an example of a jig for carrying out the present invention. Here, 41 shown in (A) is a glass holding frame, and the glass holding frame 41 has an irradiation window 42 at the center thereof for irradiating laser light as described later. 43 is a fixing screw hole. 51 shown in (B) is a glass plate, shown in (C)
61 is a sensor cell positioning frame, and the sensor cell positioning frame 61 is a recess into which the glass plate 51 can be fitted
62 has a sensor cell positioning frame 61 in this recess 62.
Is thinner than the thickness of the sensor cell 10 described above.

Reference numeral 63 denotes a sensor cell positioning hole formed by penetrating the recess 62, and the recess 62 has a plurality of sensor cell positioning holes.
63 are formed in a matrix. 64 is a screw hole for fixing the glass holding frame 41, and 65 is a mesa positioning frame 17 shown in (D).
Reference numeral 66 is a screw hole for fixing the space between and, and 66 is a pin hole for relative positioning between the frames.

The mesa positioning frame 71 has a mesa holding plate 8 shown in (E) on its lower surface.
There is a recess 72 into which 1 can be fitted, and the thickness of the plate in this recess 72 is smaller than the height of the mesa 11.
Mesa positioning holes 73 are formed at positions corresponding to the sensor cell positioning holes 63 in the above. 75 is a fixing screw hole between the frames corresponding to the screw hole 65, and 76 is a pin hole
It is a pin hole for positioning with 66. Further, in the mesa holding plate 81, 84 is a hole for a fixing screw.

Therefore, when assembling the distributed pressure sensor using such a jig, first, the FPC 16 having the through hole 26 for the mesa is placed on the mesa positioning frame 71, and the through hole 26 is positioned by the mesa. It is arranged to be aligned with the mesa positioning hole 73 of the frame 71. After that, the sensor cell positioning frame 61 is superposed on it, and the pin hole 66 is aligned with the pin hole 76 and positioned, as shown in FIG. Then, the taper pin 91 is driven, and the bidirectional positioning is fixed.

From the above, as shown in FIG. 2, the sensor cell 10 and the mesa are
The relative position between the FPC 16 and the FPC 16 can be precisely positioned. In such a state, the sensor cell 10 is inserted into each sensor cell positioning hole 63 of the sensor cell positioning frame 61.
, And then stack the glass plate 51 on top of it, and press the glass plate 51 with the glass holding frame 41 (not shown) and clamp it to the sensor cell positioning frame 61.
Hold 10 in the state shown in FIG. Then, the laser beam 27 is irradiated from the irradiation window 42 of the glass holding frame 41 (see (A) of FIG. 1) to weld the solder bumps of the electrode 14 and the conductor pattern 28 on the FPC 16.

Next, when the electrical connection between the FPC 16 and the sensor cell 10 is made by such welding, in this state, the mesa positioning frame 71 is turned upside down as shown in FIG. , The mesas 11 are fitted into the respective mesa positioning holes 73, and at this time, the adhesive 23 is applied to the side of the mesas 11 or directly below the joint 12 on the sensor cell 10, that is, the mesas positioning 73. The adhesive 23 is applied to the corresponding position.

When the mesa 11 is thus fitted into the mesa positioning hole 73, the mesa holding plate 81 is superposed on the upper portion of the mesa 11 via the elastic body 82, and the mesa positioning frame is provided so that uniform pressure can be obtained.
Waiting for the adhesive 23 to cure while being clamped at 71, removing the clamped fixing screw when the adhesive 23 is cured, and disassembling the jig. FIG. 4 shows the structure of the distributed pressure sensor manufactured in this manner.

[Effects of the Invention] As described above, according to the present invention, a first positioning member having a plurality of first positioning holes capable of individually positioning silicon cells arranged in a matrix,
When the second positioning member having the plurality of second positioning holes capable of individually positioning the pressure receiving portion are overlapped with each other, the first positioning hole and the second positioning hole are arranged at positions facing each other. None, first, the FPC is held between the first positioning member and the second positioning member such that the through hole of the FPC is aligned with the second positioning hole, and the silicon cell of the first positioning hole has the electrode of the FPC. After fitting so as to keep contact with the conductor pattern and soldering between the electrode and the conductor pattern, the pressure receiving portion is made to be in a state in which it can be adhered to the silicon cell with an adhesive, and then fitted into the second positioning member. Since even pressure is applied from above to bond, it is possible to prevent the relative position between the pressure receiving part and the silicon cell from shifting and the adhesion state to be non-uniform. It becomes possible to suppress the variation in the detection characteristics.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing each jig for carrying out the present invention, FIGS. 2 and 3 are sectional views schematically showing each step of the present invention, and FIG. FIG. 5 is a cross-sectional view showing an example of the configuration of the distributed pressure sensor obtained by the above, FIG. 5 is a perspective view showing an example of the conventional distributed pressure sensor, and FIG. 6 is another form of the conventional distributed pressure sensor. Sectional view, FIG. 7 is a plan view of a sensor cell to which the present invention is applicable, FIG. 8 is a sectional view of a detection element to which the present invention is applicable, and FIG. 9 is configured between strain gauges on the sensor cell. FIG. 10 and FIG. 11 are cross-sectional views showing each step in the conventional distributed pressure sensor manufacturing method, and FIG. 12 is a cross-sectional view showing a state of a defective product by the conventional manufacturing method. 13A to 13C show that the relative position between the sensor cell and the mesa (pressure receiving part) is good or not good. FIG. 14 is a state diagram showing goodness, FIG. 14 is a curve diagram of output characteristics obtained from each state of FIGS. 13A to 13C, and FIGS. 15A and 15B are adhesive layers between the mesa (pressure receiving portion) and the sensor cell. Sectional views showing examples of different thicknesses, FIGS. 16A and 16B are characteristic curve diagrams relating to hysteresis obtained from FIGS. 15A and 15B, respectively. 10 ... Sensor cell, 11 ... Mesa (pressure receiving part), 12 ... Joining part, 13A-13D ... Strain gauge, 14 ... Electrode, 15 ... Elastic floor, 16 ... Flexible printed wiring board (FPC), 23 ... Adhesive, 27 ... Laser light, 28 ... Conductor pattern, 41 ... Glass holding frame, 42 ... Irradiation window, 51 ... Glass plate, 61 ... Sensor cell positioning frame, 62, 72 ... Recess , 63 …… Sensor cell positioning hole, 66,67 …… Pin hole, 71 …… Mesa positioning frame, 73 …… Mesa positioning hole, 81 …… Mesa holding plate.

Claims (1)

[Claims] 1. A single crystal silicon cell having a semiconductor strain gauge for detecting strain and electrodes of solder bumps, and projecting a pressure receiving portion for receiving a vertical load is arranged in a matrix on an elastic floor, In manufacturing a distributed pressure sensor including a flexible printed wiring board having a conductor pattern electrically connected to an electrode and a through hole penetrating the pressure receiving portion formed on the single crystal silicon cell, A first positioning member having a plurality of first positioning holes capable of individual positioning of the crystalline silicon cell and a second positioning member having a plurality of second positioning holes capable of individual positioning of the pressure receiving portion are superposed on each other. The first positioning hole and the second positioning hole are positioned so as to face each other in a closed state, and the first positioning member and the second positioning member are disposed between the first positioning member and the second positioning member. The flexible printed wiring board is held so that the through hole is aligned with the second positioning hole, and the single crystal silicon cell is fitted into the first positioning hole so that the electrode keeps contact with the conductor pattern. In a state where the electrodes and the conductor pattern are welded to each other, the pressure receiving portion is set in a state in which the pressure receiving portion can be adhered to the single crystal silicon cell with an adhesive, and the pressure receiving portion is fitted into the second positioning hole. A method for manufacturing a distributed pressure sensor, wherein the pressure receiving portion is bonded to the single crystal silicon cell by applying a uniform pressure from above the pressure receiving portion.