JPH0546889B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a pressure sensor that detects the magnitude and direction of pressure. The present invention relates to a pressure sensor in which pressure sensitive modules capable of detecting force in three directions are arranged in an array.

[Prior Art] This type of pressure sensor is generally used in places where tactile sensing is to be obtained when it is necessary to know the strength of gripping force, surface pressure distribution, etc. in robot hands, etc. Research and development has been carried out for this purpose.

FIG. 3 shows an example of such a conventional pressure sensor. Here, 1 and 2 are pressure sensitive cells held perpendicularly to the groove 4 of the lower substrate 3. A pressure-receiving plate 5 is provided on the upper surface between the two pressure-sensitive cells 1 and 2 that are arranged in parallel to each other, thereby forming a pressure-sensor module 6 as one unit.

Furthermore, as shown in FIG. 4, for example, each pressure-sensitive cell 1 and 2 has a plurality of strain gauges 7 formed at predetermined positions on the side surface of each pressure-sensitive cell 1 and 2 to reduce the load acting on each pressure-receiving plate 5. By transmitting it to these strain gauges 7 via pressure sensitive cells,
The force can be separated into a horizontal component force Fx, Fy along the pressure receiving plate 5 and a component force Fz perpendicular to the pressure receiving plate 5 for detection.

If the pressure sensitive cells 1 and 2 described above are constructed of, for example, a single crystal silicon wafer, and the strain gauge 7 is formed on the surface thereof using the diffusion principle of a semiconductor process,
The size of the pressure sensitive cell can be made very small, and as a result, the pressure sensor module 6 can also be made small.

The shapes of such miniaturized pressure sensitive cells shown in FIGS. 5 and 6 are conventionally known. The pressure sensitive cell 8 in FIG. 5 is a ring-shaped pressure sensitive cell, which has a circular hole 9 in its center, and projections 10 for insertion into grooves at both vertical ends of the pressure receiving plate. There is. The pressure sensitive cell 11 in FIG. 6 has an octagonal outer periphery, has a circular hole 12 in its center, and has protrusions at both ends of the pressure receiving plate in the vertical direction for insertion into the groove. 13 are formed.

[Problems to be Solved by the Invention] However, such conventional pressure sensitive cells have the following drawbacks.

It is difficult to process the outer periphery.

In the ring-shaped cell 8 shown in FIG. 5, the outer periphery must be processed into a curved surface, and in the octagonal cell shown in FIG. 6, the outer periphery must be finished with multiple surfaces. However, it is very difficult to precisely process silicon, which is a hard and brittle material, into such a complex shape, and even if it could be processed, it would take a long time.

Stress concentration occurs.

In the pressure sensor shown in FIG. 3, forces are applied to the pressure sensitive cells 1 and 2 in all directions. However, in the case of the pressure-sensitive cells 8 and 11 shown in FIGS. 5 and 6, there are notches 14 and 15 at the bases of the projections 10 and 13 for insertion into the grooves, so stress is applied to these portions 14 and 15. Concentration may occur. According to experiments, the stress generated in this stress concentration area may be the largest among the stresses generated in the pressure-sensitive cell, and may cause the pressure-sensitive cell to break.

The pad density at the wiring outlet is high.

In order to extract the signal inside the pressure sensitive cell to the outside,
Wiring between the pressure sensitive cell 1 and the lower substrate 3 is connected, and it is necessary to provide a pad portion at the tip of each wiring in order to facilitate wiring connection. A pressure sensitive cell 8 as shown in FIGS. 5 and 6,
In the case of No. 11, it is necessary to provide pads at the base portions of the projections 10 and 13, but since this portion is narrow, the pads must be made smaller and their density must be increased.

Assembly work is complicated.

To assemble the pressure sensor as shown in Figure 3,
The protrusions 10 or 13 of the pressure sensitive cells must be inserted one by one into the groove 4 of the lower substrate 3 for assembly. In order to increase the detection resolution of a pressure sensor, the pressure-sensitive cell must be made smaller.
This insertion and assembly work is complicated.

In order to avoid the complexity of such assembly work, a pressure sensor manufacturing method involves assembling a plurality of pressure sensitive cells in a connected state, and cutting and separating them into individual pressure sensor modules after completion of adhesion. has already been proposed by the present inventor (Japanese Patent Application No. 58-201962, Japanese Patent Application No. 58-205251)
issue).

In view of the above-mentioned points, the present invention is suitable for the above-mentioned method of manufacturing a pressure sensor that is easy to assemble, facilitates processing of the outer periphery of a pressure-sensitive cell, avoids stress concentration, and eliminates the need for a wiring extraction portion. It is an object of the present invention to provide a pressure sensor equipped with a pressure-sensitive cell having a shape that can be formed in a wide range of shapes.

[Means for Solving the Problems] In order to achieve the present object, the present invention provides two sensors made of single crystal silicon in a ring shape or a shape similar to the ring shape and arranged vertically and facing each other on a substrate. One pressure-sensitive module is composed of a pressure cell and a pressure-receiving plate attached to the top surface of two pressure-sensitive cells, and a strain gauge formed on the side surface of the pressure-sensitive cell absorbs the load applied to the pressure-receiving plate. In a pressure sensor that separates and detects a horizontal component force Fx parallel to the side surface of the pressure sensitive cell, a horizontal component force Fy perpendicular to the side surface of the pressure sensitive cell, and a vertical component force Fz perpendicular to the pressure receiving plate. , a plurality of pressure-sensitive cells are connected at their lower portions, and each pressure-sensitive cell has a center hole, and the outer periphery of each pressure-sensitive cell is adjacent to each other; a first hole intermediate between the two pressure-sensitive cells; It is characterized by having a shape formed by second holes that overlap each other at the upper and lower positions of the hole, and a cut groove that communicates the first and second holes.

[Function] In the present invention, the shape of the unit pressure-sensitive cell is formed by a center hole, a plurality of holes forming the outer peripheral surface, and a cut for separating adjacent pressure-sensitive cells. Machining of the surface becomes easier, improving machining accuracy, and there are no notches, eliminating stress concentration. Furthermore, since the pressure-sensitive cell has arms that generate less stress even when a load is applied to the pressure-sensitive cell in any direction, a semiconductor element that needs to avoid the influence of stress is formed in this arm. becomes possible.

Furthermore, in the present invention, since the plurality of pressure-sensitive cells are connected at the lower part, the plurality of pressure-sensitive cells can be handled as one unit, making assembly work easier, and a pad for taking out the wiring is provided at the connection part. By forming the pad, the density of the pad can be lowered.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a configuration example of a pressure sensor of the present invention, and FIG. 2 shows an embodiment of a pressure sensor constituting the pressure sensor. FIG. 2 shows a strip-shaped triple cell 26 in which three pressure-sensitive cells 25 are connected at the bottom.
The number is not limited to one, and the number may be increased as necessary. However, since strain gauges and other semiconductor elements are formed on the surface of the pressure sensitive cell 25 by a semiconductor process, considering the yield of current semiconductor processes, it is thought that the optimal number of elements to be connected is about 3 to 5. It will be done.

As shown in the figure, the pressure sensitive cell 25 of this example has a circular center hole 27, and two pressure sensitive cells on both sides adjacent to the outer periphery of the center hole 27 have two pressure sensitive cells located in the center. A relatively small circular hole 28 formed;
It has a double circular hole 29 which overlaps each other with a slight shift in the horizontal direction at the upper and lower positions of the circular hole 28, and a cut groove 30 whose upper part is opened at the above-mentioned intermediate position, and each cut groove 30 pass through one circular hole 28 and two circular holes 29, respectively.

In the pressure sensitive cell 25 having such a shape, the notches 14 and 15 as shown in FIGS. 5 and 6 are used.
Since this eliminates stress concentration, stress concentration can be avoided. In addition, in this shape, the small diameter hole 28 and the large diameter hole 29
An arm portion 31 is inevitably formed between the pressure sensor 25, but no matter what load is applied to the pressure sensor 25, the stress generated in the arm portion 31 is greater than the stress generated in other parts. It has been experimentally confirmed that it is also very small. Therefore, the arm portion 31 can be formed with a semiconductor element (for example, an analog switch, a temperature sensor, etc.) that would be in trouble if subjected to stress.

Furthermore, since the single crystal silicon that constitutes the pressure sensitive cell 25 is a hard and brittle material, it is relatively difficult to process, but since each hole 27, 28, 29 is a circular hole,
The hole machining can be done relatively easily and accurately by laser beam machining or the like.

Therefore, if a pressure sensor is equipped with a plurality of pressure-sensitive cells that have an easy-to-process shape that allows the outer shape to be obtained using only a combination of circular holes and a straight cut, the processing time for the pressure-sensitive cells can be shortened and Since the dimensional accuracy of each pressure-sensitive cell is improved and the shape is uniform, there is an advantage that variations in detection accuracy of the pressure-sensitive cells 25 are reduced.

Further, as mentioned above, the stress generated in the arm portion 31 is small, so even if the length of the arm portion 31 changes slightly,
This has little effect on the overall stress state. Therefore, even if the machining accuracy of the cut groove 30 between the two pressure sensitive cells is somewhat degraded due to its position or groove width, the detection accuracy of the pressure sensitive cells 25 will not be greatly affected.

Furthermore, a pad 33 for extracting a signal within the pressure-sensitive cells can be provided at the connecting portion 32 that connects the pressure-sensitive cells 25 at the bottom. Since the connecting portion 22 has a wide width, it is possible to form the pad 33 with sufficient margin.

Further, since the three pressure sensitive cells 25 can be handled as one unit in the triple cell 26, it goes without saying that the assembly work of inserting the three pressure sensitive cells 25 into the groove 41 of the substrate 40 becomes easier.

The method of manufacturing the pressure sensor unit 42 as shown in FIG. 1 from the triple cell 26 described above has already been proposed by the present inventor (Japanese Patent Application No.
No. 272025), detailed explanation thereof will be omitted. In addition,
43 is a pressure receiving plate.

[Effects of the Invention] As explained above, according to the present invention, a plurality of pressure sensitive cells of a pressure sensor are connected at the lower part thereof, and each pressure sensitive cell having a center hole is formed with a plurality of holes on the outer periphery thereof. Since the shape is formed by the cut grooves between adjacent pressure sensitive cells, the following advantages can be obtained.

It becomes easier to process the outer periphery of the pressure sensitive cell.

Stress concentration can be avoided.

Wire extraction pads can be placed with plenty of room.

Assembly work becomes easier.

Analog switches and temperature sensors can be formed.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an example of a pressure sensor unit of the present invention, Fig. 2 is a front view showing the shape of a pressure sensitive cell constituting the pressure sensor unit, and Fig. 3 is an example of a conventional pressure sensor. FIG. 4 is a perspective view showing the position of a strain gauge formed on the surface of a conventional pressure-sensitive cell, and FIGS. 5 and 6 are front views showing the shape of the conventional pressure-sensitive cell, respectively. 25...pressure sensitive cell, 26...triple cell, 27...
... center hole, 28 ... hole, 29 ... overlapping holes, 30 ... cut groove, 31 ... arm, 32 ...
Connecting portion, 33... Pad, 40... Lower board, 4
1...Groove, 42...Pressure sensor unit, 43...
...Pressure plate.

Claims (1)

[Scope of Claims] 1. Two pressure-sensitive cells made of ring-shaped or similar ring-shaped single crystal silicon arranged vertically and facing each other on a substrate, and the upper surfaces of the two pressure-sensitive cells. One pressure-sensitive module is constructed by the pressure-receiving plate attached to the pressure-sensitive cell, and the load applied to the pressure-receiving plate by the strain gauge formed on the side surface of the pressure-sensitive cell is transferred to a horizontal plane parallel to the side surface of the pressure-sensitive cell. component force
Fx and the horizontal component Fy perpendicular to the side surface of the pressure sensitive cell
and a vertical component Fz in a direction perpendicular to the pressure-receiving plate, the plurality of pressure-sensitive cells are connected at the lower part thereof, and each pressure-sensitive cell has a center hole. a first hole in the middle between two pressure sensitive cells whose outer peripheries are adjacent to each other; a second hole that overlaps each other above and below the first hole; and the first and second holes. A pressure sensor characterized by having a shape formed by a cut groove that communicates with the hole.