JPH03163321A - Manufacture of distribution type pressure-sensitive sensor - Google Patents

Abstract

PURPOSE:To make it possible to achieve durable electric connections at a right attitude by heating a sensor cell and a flexible printed wiring board through a glass plate, and soldering and connecting the solder bump on an electrode to a conductor pattern. CONSTITUTION:A board 6 is fixed and held between a positioning member 21 for determining the position of a flexible printed wiring board 6 and a fixing frame 31 having a through window 32. A pressure receiving part 2 of each cell of a sensor 1 is coupled into a cell positioning hole 24 of the member 21 by way of a through hole 6A, and the position is determined. Under this state, an electrode 4A of the cell 1 is brought into contact with the conductor pattern of the board 6. A glass plate 9 is mounted on the through window 32 of the fixing frame 31. Soldering between the electrode and the conductor pattern is performed by heating from the upper part of the glass plate 9. The cell 1 is held in the space in the through window 32. Even if the heating is locally performed, the splashing-up of the solder is prevented with the glass plate 9, and tombstones are not formed. Therefore, the state of the stabilized highly- reliable electric connection is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a distributed pressure sensor, and more specifically, a plurality of sensor cells attached to a robot hand to detect the force received from an object to be grasped are arranged in a matrix. arranged,
This paper relates to a method for manufacturing distributed pressure sensors in which a flexible printed circuit 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 and limited environment, so there are limits to the work content and robot capabilities. ．． For example, in the case of a pick-and-place robot, which places parts in assembly line work, it is limited to a series of specific operations such as grasping a specific part, and the function is to select and grasp dissimilar parts. does not have.

However, recently, as robots have become more intelligent, visual sensors and pressure sensors that correspond to human senses have been developed, and robots that can operate in various environments are being put into practical use. There is a distributed pressure sensor as a pressure sensor for intelligent robots, but such a sensor is attached to a robot hand, etc., and when the robot hand grasps an object, it detects the output from the sensor and performs a feed hack. By controlling the gripping force of an object,
It is possible to recognize hardness. FIG. 4 shows an example of a conventional distributed pressure sensor. In this example, two layers of fine conductive rubber strips 101 and 102 that intersect at right angles to each other are combined, and when a force is applied perpendicularly to the rubber strip array surface, the contact area between the rubber strips 101 and 102 is Since the area increases and the resistance changes, this is detected to determine the magnitude of the applied force.

However, with such distributed pressure sensors, it is not possible to obtain an output proportional to the applied force, and the output becomes non-linear.
Another disadvantage is that it is not suitable for detecting force distribution in a high density. In order to solve these drawbacks, distributed pressure sensors as shown in FIGS. 5 to 8 have been proposed.

In Figs. 5 and 6, 1 is the sensor cell, 2 is the pressure receiving part installed on the sensor cell 1, and 3A to 3B are arranged around the receiving pressure @2 on the sensor cell l, and the pressure generated on the sensor cell l. 4A is a solder bump electrode also placed on the sensor cell 1; 5 is an elastic floor that holds the sensor cell 1 and acts as an elastic body; 6 is a semiconductor strain gauge placed on the sensor cell 1; This is a flexible printed wiring board that is arranged and electrically connected to the electrodes 4A of the solder bumps. Here, the semiconductor strain gauges 3A to 3D are incorporated in a Wheatstone bridge circuit as shown in FIG.
The force applied to the sensor cell 1 is detected as a strain value by extracting the resistance change in 3D from diagonally positioned terminals, and it supplies power to the bringer circuit and output signals from the semiconductor strain gauges 3A to 30. Electrode 4A
, can be taken out to the outside via the flexible printed wiring board 6.

Therefore, in the manufacturing process of such a distributed pressure sensor, when performing fine soldering 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 was placed on the frame 7 which had a hole into which the part 2 could be inserted, and the pressure receiving part 2 was fitted into the through hole 6A of the flexible printed wiring board 6 with the sensor cell 1 up and down. A laser beam was irradiated from the back side of the upper sensor cell 1 to melt the solder bumps of IHFi4A 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 a distributed pressure sensor, as shown in FIG.
When the sensor cell 1 is locally heated, the side of the sensor cell 1 opposite to the side to be soldered will spring up, and the sensor cell 1 will be connected in an inclined (also called tombstone) state. By the way, the sensor cell 1 and the flexible printed wiring base 6 should originally be connected in parallel, and the detection function will be impaired in the above-mentioned connection state. Also, as shown in Figure 10,
When the sensor cell 1 is placed on the solder land 4 of the flexible printed wiring board 6 with a shift R, the sensor cell 1 is connected with an angle shifted by θ degrees with respect to the arrangement direction number 2 of the solder land 4. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a reliable, correct and durable electrical connection between the electrodes of a plurality of sensor cells and the solder lands of a flexible printed wiring board. The purpose of this paper is to propose a manufacturing method for a distributed pressure sensor that achieves the following. [Means for Solving the Problems] In order to achieve the above object, the present invention provides a sensor cell having a semiconductor strain gauge for strain detection and a solder bump electrode, and having a protruding pressure receiving part for receiving a load. In manufacturing a distributed pressure sensor, in which a flexible printed wiring board is provided on a sensor cell, in which conductor patterns electrically connected to electrodes and through-holes passing through pressure-receiving parts are formed. , a positioning member that has a recess that matches the shape of the flexible printed wiring board, a positioning member that has a plurality of sensor cell positioning holes that allow the pressure receiving part to fit into the recess, and a cutout window that matches the shape of the flexible printed wiring board. Then, the flexible printed wiring board is fixed with a fixing frame that can be held around the cutout window, and the pressure receiving part of each sensor cell is fitted into the sensor cell positioning hole of the positioning member, so that the electrodes are connected to the conductive pattern. A glass plate is placed on top of the cutout window so that each sensor cell is held in the space of the cutout window formed between the glass plate and the flexible printed wiring board. This method is characterized in that the sensor cell and the flexible printed wiring board are heated through the glass plate to connect the tFj solder bumps to the conductor pattern.

[Function] According to the present invention, the flexible printed wiring board is fixedly held between the positioning member that positions the flexible printed wiring board and the fixed frame having the cutout window, and then the held flexible printed wiring board is Fit the pressure receiving part of each sensor cell into the sensor cell positioning hole of the positioning member through the through hole and position it, and in this state, the electrode of each sensor cell maintains contact with the conductor pattern of the flexible printed wiring board, and then fix the fixed frame. A glass plate is placed over the cut-out window of the sensor, and the glass plate is heated to solder between the electrode and the conductor pattern, and the sensor cell is held in the space of the cut-out window. Even if the glass is heated locally, the temporary glass will prevent it from popping up and will not cause tombstones. Therefore, a stable and highly reliable electrical connection can always be obtained.
[Example] The present invention will be described below in detail and specifically based on the drawings. Figure 1 shows an example of a jig for carrying out the present invention. Here, 2l is a positioning member for positioning and holding the flexible printed wiring board 16, and includes a recess 22 and a screw hole 23 shaped to match the outer periphery of the flexible printed wiring board 6, and a flexible printed wiring board 6.
It has a sensor cell positioning hole 24 that is bored at the same interval as the through hole 6A provided in the I base 6 and into which the pressure receiving part of the sensor cell can be inserted. It is made slightly shallower than the board thickness of the 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 protruding the pressure receiving part 2 of the sensor cell 1 (see FIG. 2). 3l is a fixed frame for holding the flexible printed wiring board 6 on the positioning member 2l, and the fixed frame 3l has a similar shape that is slightly smaller than the outer circumference of the flexible printed wiring board temporary 6, and is penetrated to direct the laser beam downward. It has a cutout window 32 for guiding the glass plate 32 to the fixing frame 31, and also 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 assembled using the jig described above to obtain an electrical connection. First, as shown in FIG. Place the flexible printed wiring board 6 so that they fit together, and align the fixing hole 34 with the screw hole 23 of the positioning member 21 with the through hole 6^ of the flexible printed wiring board 6 aligned with the sensor cell positioning hole 24. In this way, the fixed frame 31 is overlapped with the positioning member 21 using the bolt 35.
The flexible printed wiring board 6 is held and fixed between the two. Next, after applying a surfactant to each of the solder runs l''4 of the flexible printed wiring board vi6, the pressure receiving part 2 of the sensor cell l is fitted into the through hole 6A of the flexible printed wiring board 6, and the solder on the sensor cell 1 is bump t
Keep JM4A and solder land 4 in contact.
Then, in this state, the glass plate 9 is placed in the recess 33 on the upper surface of the fixed frame 3. At this time, sensor cell 1 and glass v
i. 9, so that some margin is maintained between the two.
It is desirable that the flexible printed wiring board 6 and the sensor cell l be maintained at least to an acceptable degree of parallelism. Note that if the sensor cell 1 and the glass temporary 9 are in contact with each other, there is a risk that the sensor cell 1 will be pressed by the glass plate and the sensor cell will be damaged, or that the pressure will crush the electrode 4A of the solder bump and create a bridge in the solder. However, in this embodiment, since a slight gap is provided between the sensor cell 1 and the glass temporary 9 as described above, such a problem does not occur. By heating the sensor cell 1 and the flexible printed wiring board 6 locally or entirely using a laser beam or the like from above the glass plate 9 of the jig set in this way, the electrodes 4A of the solder bumps are melted and the solder lands 4 are heated. It can be electrically connected. FIG. 3 shows the state of the distributed pressure sensor in which a plurality of fj & thin solders can be soldered between each sensor cell 1 and the flexible printed wiring board 6 while maintaining the correct posture according to the present invention. show.

C. Effects of the Invention] As described above, according to the present invention, the positioning member has a plurality of sensor cell positioning holes in which the pressure receiving portions of the sensor cells can be respectively fitted in recesses that match the shape of the flexible printed wiring board. , has a cutout window corresponding to the shape of the flexible printed wiring board, and a fixing frame that can hold the periphery of the flexible printed wiring board to hold the flexible printed wiring board between them. Fit the pressure receiving part of the sensor cell into the sensor cell positioning hole of the positioning member, position the sensor cell so that the electrodes of the sensor cell are in contact with the conductor patterns of the flexible printed wiring board, and place the glass plate on top of the cutout window. Each sensor cell is held in the space of the cutout window and heated through the glass plate,
Since soldering is performed between the electrode and the conductor pattern, heating is performed with the flexible printed wiring board and the sensor cell maintained in their normal postures, thereby preventing tombstones from occurring. It is now possible to perform highly reliable fine soldering with good solder wettability.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of a jig for carrying out the present invention, Fig. 2 is a sectional view showing the process of an embodiment of the present invention, and Fig. 3 is a distributed pressure sensor according to the present invention. 4 is a perspective view showing the i-prevention of a conventional distributed pressure sensor; FIG. 5 is a plan view of a sensor cell to which the present invention can be applied; and FIG. A cross-sectional view of a possible pressure sensor, Fig. 7 is a diagram of the structure of a bridge circuit arranged between semiconductor strain gauges on a sensor cell, Fig. 8 is a cross-sectional view of a conventional soldering method, and Fig. 9 is a conventional example. FIG. 10 is a cross-sectional view showing a defective condition of the conventional example, and FIG. 10 is a plan view showing another defective condition of the conventional example. l: Sensor cell, 2: Pressure receiving part, 4: Solder land, 4A
: electrode, 6: flexible printed wiring board, 6A: through hole, 9: glass plate, 2l: positioning member, 22: recess, 23: tapped hole, 24: sensor cell positioning hole, 3l:
Fixed frame, 32: Cutout window, 33: Recess, 34: Fixed hole.

Claims (1)

[Claims] 1) Sensor cells having semiconductor strain gauges for detecting strain and electrodes of solder bumps, each having a protruding pressure-receiving part for receiving a load, are arranged in a matrix, and the electrodes are electrically connected to each other. In manufacturing a distributed pressure sensor in which a flexible printed wiring board having a conductor pattern connected to the sensor cell and a through hole passing through the pressure receiving part is provided on the sensor cell, a positioning member having a recessed portion and a plurality of sensor cell positioning holes into which the pressure receiving portion can be fitted; and a cutout window corresponding to the shape of the flexible printed wiring board; The flexible printed wiring board is fixed by a fixing frame that can hold the periphery of the board around the cutout window, and the pressure receiving parts of the individual sensor cells are fitted into the sensor cell positioning holes of the positioning member, so that the electrodes are connected to the conductor. The glass plate is positioned so as to maintain contact with each pattern, and a glass plate is placed on the cutout window, and each of the cutouts is placed in the space of the cutout window formed between the glass plate and the flexible printed wiring board. A distributed pressure sensor characterized in that the sensor cell is held, the sensor cell and the flexible printed wiring board are heated through the glass plate, and the solder bumps of the electrode are soldered to the conductor pattern. Production method.