JPH0329319B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for three-dimensionally connecting a tactile sensor to a wiring board.

[Prior Art] Conventional tactile sensors used in robots, manipulators, etc. are formed flat, such as conductive sheets, and are often of the type that simply detects pressing force. Therefore, there is no need for special considerations regarding the substrate on which such a sensor is provided. However, in recent years, there has been a desire to develop sensors that have functions similar to the human tactile sense for objects and can obtain information such as contact and slippage.For example, tactile sensors that can detect force components in three directions are being developed. It is being considered. In such a tactile sensor, the shape of the sensor is not planar, but must have a three-dimensional structure relative to the substrate, and in particular, the substrate on which such a sensor is placed is becoming more and more dimensional as the sensor becomes three-dimensional. The wiring density must be high, and the connection strength must be sufficient to withstand external forces applied to the pressure-receiving surface of the sensor. Therefore, it has been considered to arrange such tactile sensors in a matrix on a wiring board.

However, when a three-dimensional sensor as described above is connected two-dimensionally to a wiring board using the conventional method, sufficient mechanical strength cannot be maintained, and there are also major problems in the electrical connection itself.

Figure 2 shows how the tactile sensor is connected to the wiring board. In the figure, 1' is a wiring board, 2 is a pressure receiving plate made of ceramic or the like, 3 is a tactile sensor using a semiconductor strain gauge made of a Si wafer in which a p-type or n-type dopant is appropriately diffused, and 4 is a tactile sensor that uses a semiconductor strain gauge on the sensor 3. The electrodes are provided by a method such as embedding, and the appropriate number is determined depending on the design. Reference numeral 5 denotes an electrode provided in advance on the wiring board, and the electrode 4 and the electrode 5 are electrically connected. Here, an example will be shown in which one pressure receiving plate 2 is bonded to two tactile sensors to detect forces in three directions. It is desirable that the plurality of pressure receiving plates 2 bonded on the plurality of tactile sensors 3 are on the same plane, and for this reason, not only the positional relationship between the pressure receiving plates 2 and the sensors 3 but also the position of the sensor 3 and the wiring board 1 is determined. Relationships also need to be defined precisely. For example, a bridge wiring pattern is precisely formed in the tactile sensor 3 by a semiconductor process, and the position of the electrode 4 connected to this wiring pattern is also precise. In order to arrange a plurality of pressure receiving plates 2 on the same plane, this electrode 4 and
The electrode 5 on the wiring board must be connected while maintaining accurate positional relationship.

If the tactile sensor 3 is placed on the board 1 and the electrodes 4 and 5 are connected by soldering or the like, it is not possible to maintain sufficient strength after connection, so a groove is provided on the wiring board 1 to connect the tactile sensor Attempts have been made to create a three-dimensional connection by inserting the legs of No. 3 into the grooves to obtain sufficient strength. FIG. 3 is a perspective view showing how the groove 6 provided in the substrate 1 and the leg portion 3A of the tactile sensor 3 fit together, and FIG. 4 is a sectional view thereof. In order to bond the tactile sensor 3 to the substrate 1, as shown in FIG. 4, adhesive 7 is applied to the groove 6 of the substrate 1, and the leg portion 3A of the sensor 3 is fitted into the groove 6 and bonded. After that, electrode 4 and electrode 5 are connected by soldering. By such a method, the sensor 3 and the substrate 1 are bonded with sufficient strength. However, since the electrode 4 provided on the sensor 3 is a thin layer plated with Ni or the like, the electrode 4 also gets into the groove 6, as shown in FIG. Even if the bottom surface 6A is provided parallel to the surface of the substrate 1, it is extremely difficult to maintain the lower end of the leg portion 3A at a constant distance from the bottom surface 6A of the groove 6. ) and the lower end of the electrode 4 differs for each tactile sensor or even for both ends of the same tactile sensor 3. FIG. 5 is a side view of the tactile sensor 3 seen from the electrode 4 side to explain the situation.
At one end of the tactile sensor 3. The height b of the electrode 4 from the surface of the substrate 1 is different from the height c at the other end, and as a result, the pressure receiving plate 2 on the sensor 3 is
It will not be parallel to the substrate 1, and it will no longer be possible to arrange a plurality of pressure receiving plates on the same plane.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned conventional drawbacks, maintains sufficient connection strength that will not be impaired even when forces are applied in three directions, and enables accurate alignment. It is an object of the present invention to provide a method for connecting a tactile sensor and a board, which provides a highly reliable connection state.

[Means for Solving the Problems] In order to achieve the above object, in the method for connecting a tactile sensor and a substrate of the present invention, a plurality of bump-shaped electrodes are provided in parallel on the tactile sensor, and a plurality of bump-shaped electrodes are provided on the substrate. The legs of the tactile sensor are inserted into the grooves up to the positions of the plurality of bump-shaped electrodes, and the lower edges of the plurality of bump-shaped electrodes are placed one-on-one with the plurality of electrodes arranged side by side on the substrate. After bonding the legs and the substrate so that the lower edges of the plurality of bump-shaped electrodes are parallel to the surface of the substrate, the bump-shaped electrodes of each pair and the electrodes are brought into contact with each other as a pair. Then, cream solder is applied over the entire length of the plurality of bump-shaped electrodes arranged in parallel, and a laser beam is irradiated to connect the plurality of bump-shaped electrodes and the plurality of electrodes on the substrate. Solder each pair separately.

[Function] Since the legs of the tactile sensor are fitted into the grooves provided in the upper layer of the wiring board and bonded, they are firmly joined, and the bump-shaped electrodes provided in advance on the sensor act as a stopper during fitting. A well-aligned fit is achieved, and since cream solder is applied around the bump and irradiated with a laser beam, fine right-angle wiring connections are possible.

[Examples] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the state in which the tactile sensor 3 is fitted into the groove of the substrate 1. A bump-shaped electrode 8 is provided at a desired position on the tactile sensor 3. Soldering was performed using a mask on the Ni base formed in the same manner as the conventional electrode 4.
Electrodes 8 made of solder bumps with a thickness of 100 to 150 μm can be formed. At this time, by using a mask, the lower edge of the electrode 8 can be made accurately parallel to the adhesive surface of the tactile sensor 3 and the pressure receiving plate 2.

FIG. 6 is a sectional view showing how the leg portion 3A fits into the groove 6. The leg portion 3A is inserted into the groove 6 coated with adhesive, but the bump-shaped electrode 8 is in contact with the electrode 5 provided on the substrate 1 and does not enter the groove 6.
As mentioned earlier, the lower edge of the bump-shaped electrode 8 is parallel to the bonding surface between the tactile sensor 3 and the pressure receiving plate 2, so the bonding surface of the tactile sensor 3 and the pressure receiving plate 2 is parallel to the surface of the substrate 1. . FIG. 7 is a side view of the tactile sensor 3 seen from the side where the bump-shaped electrode 8 is provided to explain the state, and the height b from the surface of the bump-shaped electrode 8 at one end of the sensor 3 is is equal to the height c at . Therefore, the pressure receiving plate 2 on the tactile sensor 3
is parallel to the substrate 1, and the plurality of pressure receiving plates 2 are located in the same plane.

Next, the connection between the bump-shaped electrode 8 of the tactile sensor 3 bonded to the substrate 1 in this manner and the electrode 5 on the substrate 1 will be explained. Since the widths of the electrodes 5 and the bump-like electrodes 8 are both about several hundred micrometers, a normal soldering iron cannot be used, so a laser soldering method is used. However, even if the solder bumps constituting the bump-shaped electrode 8 are melted by laser irradiation, a good connection with the electrode 5 cannot be obtained. Therefore, as shown in FIG. 8, cream solder 9 is applied across both electrodes 5 and 8, and the laser beam 10 is
Good soldering 11 can be obtained by moving the laser beam 10 while partially irradiating the soldering. Even if the cream solder 9 is applied between adjacent electrodes, when the cream solder is melted by laser beam irradiation, the molten solder selectively gathers in areas with good solder wettability, and the surface tension As a result, the molten solder concentrates on the electrode and does not remain in the middle of the electrode. Therefore, the irradiation area of the laser beam is not the area of one electrode, but the area of the 8th electrode.
As shown in the figure, multiple locations can be irradiated simultaneously. The perspective view of FIG. 9 shows the completed soldering process in this manner.

[Effects of the Invention] As explained above, according to the present invention, a visual sensor is provided with a plurality of bump-shaped electrodes arranged in parallel, and a leg portion of a tactile sensor is placed in a groove provided in a substrate using a plurality of bump-shaped electrodes. The lower edges of the plurality of bump-shaped electrodes are brought into contact with the plurality of electrodes arranged in parallel on the substrate as a one-on-one pair, and the lower edges of the plurality of bump-shaped electrodes are After gluing the legs and the board with the edges parallel to the surface of the board,
A plurality of bump-shaped electrodes are provided in parallel and across each pair of bump-shaped electrodes, and cream solder is applied over the entire length of the electrodes and a laser beam is irradiated to form a plurality of bump-shaped electrodes. Since the bump-shaped electrode and the plurality of electrodes on the substrate are soldered to each pair, the following effects are achieved.

When the tactile sensor and the groove were fitted together, the lower edge of the bump-shaped electrode was brought into contact with the electrode (ie, the shoulder of the groove) provided on the substrate. Therefore, the lower ends of the legs of the tactile sensor are kept at a constant distance from the bottom surface of the groove, regardless of the amount of adhesive in the groove. Therefore, the top surface of the tactile sensor is always parallel to the substrate surface, making it possible to significantly improve the positioning accuracy of the tactile sensor, particularly in the vertical direction.

Cream solder is applied over the entire length of the bump-shaped electrode and the electrode provided on the substrate, so when the laser beam is irradiated, the heat is absorbed by the cream solder. Therefore, it is possible to prevent the bridge wiring pattern, etc., which is normally formed in a tactile sensor and which is precisely formed by a semiconductor process, from being burnt out.

As mentioned above, since the lower edge of the bump-shaped electrode is brought into contact with the electrode provided on the substrate, even if the adhesive in the groove deteriorates, the bump will still connect the tactile sensor to the substrate. A strong bond is maintained. Therefore, even when an external force is applied to the tactile sensor, it is possible to prevent the joint portion, which is a fine right-angled wiring connection, from being damaged.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an embodiment of the present invention, Fig. 2 is a perspective view illustrating a tactile sensor, Fig. 3 is a perspective view illustrating the fit between the tactile sensor and the groove of the substrate, and Fig. 4 is a perspective view of a conventional tactile sensor. 5 is a side view of the connection method, FIG. 6 is a sectional view of the connection method of the present invention, FIG. 7 is a side view of the connection method, and FIG. 8 is a side view of the soldering method of the present invention. FIG. 9 is a perspective view of a tactile sensor connected by the method of the present invention. 1... Substrate, 2... Pressure receiving plate, 3... Tactile sensor, 4, 5... Electrode, 6... Groove, 7... Adhesive,
8... Bump-shaped electrode, 9... Cream solder, 1
0... Laser beam, 11... Soldering part.

Claims (1)

[Claims] 1. A tactile sensor is provided with a plurality of bump-shaped electrodes arranged in parallel, and a leg portion of the tactile sensor is inserted into a groove provided in a substrate up to the position of the plurality of bump-shaped electrodes. The lower edges of the bump-shaped electrodes are brought into contact with a plurality of electrodes arranged in parallel on the substrate as a one-to-one pair, and the lower edges of the plurality of bump-shaped electrodes and the surface of the substrate are parallel to each other. After bonding the leg portion and the substrate,
Cream solder is applied over the entire length of the plurality of bump-shaped electrodes provided in parallel and across each pair of the bump-shaped electrodes and the electrode, and a laser beam is applied to the bump-shaped electrodes. A method for connecting a tactile sensor and a substrate, characterized in that the plurality of bump-shaped electrodes and the plurality of electrodes on the substrate are soldered for each pair.