JPS6410118B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention When automatically wiring discrete wires on a printed circuit board, it is required that the distance between the bonding pad of the printed circuit board and the bonding tool be constant. be done. Therefore, if the printed circuit board is warped or has poor flatness, it is difficult to maintain this distance constant. The present invention relates to an apparatus for automatically measuring the flatness of a printed circuit board in order to enable automatic wiring even when the flatness of the printed circuit board is poor.

(b) Background of the Technology In printed circuit boards, in addition to wiring using inner layer patterns, wiring with discrete wires is widely practiced. FIG. 1 shows wiring using discrete wires, in which the starting end of a discrete wire 1 is connected to a pad 2a on a printed circuit board, and the terminal end is connected to another pad 2b on the printed circuit board. This discrete line is an example in which a signal line and a ground line are paired, where 1s is a signal line and 1g is a signal line.
is the ground line.

Such wiring has come to be automatically performed by automatic wiring devices. In this case, on the X-Y table, move the starting end of the discrete wire 1 onto the pad 2a at position A, perform bonding to the pad 2a, and then indicate the end position of the discrete wire with another B. Move it to the connection position of pad 2b. Then, by bonding the terminal end to the pad 2b and cutting it, a discrete wiring whose both ends are connected to the pads 2a and 2b as shown in the figure is completed.

The starting end of the discrete wire 1c cut at position B is again transferred to another wiring position, for example position C, on the X-Y table and soldered to the pad 2a. Then, the terminal end is cut at position D in the same manner as described above.

(c) Prior art and its problems FIG. 2 is a longitudinal sectional view showing a state in which discrete wires are bonded. Printed circuit board 3
With the wire guide 5 and bonding tool 6 positioned on the pad 4, the discrete wire 1 is pressed onto the pad 4 with the tip of the bonding tool 6, and the laser beam 7 is irradiated to melt the preliminary solder. Move and bond.
In this case, unless the distance between the wire guide 5 or the bonding tool 6 and the pad 4 is constant, bonding cannot be performed reliably and stably.

By the way, it is fine as long as the flatness of the printed circuit board is constant, but if it is warped or has poor flatness, the pads 4 and wire guides 5 may be bonded at raised positions and recessed positions. The distance from the tool 6 is different, and the reliability of bonding is reduced.

(d) Purpose of the Invention The present invention solves these problems in conventional automatic wiring devices, and makes it possible to always keep the distance between the bonding tool or wire guide and the pad constant even when the flatness of the printed circuit board is poor. The purpose is to

(e) Structure of the Invention In order to achieve this object, the present invention provides an automatic wiring system that automatically performs wiring by bonding discrete wires to pads of a printed circuit board using a laser beam. This is a device for measuring the degree of power, and includes a measuring bit that is arranged perpendicular to the surface of a printed circuit board and moves up and down by a motor. The measuring bit is attached to a holder via a biasing means for biasing it in a downward direction, and the holder is connected to a motor via a vertically moving mechanism. This method requires that the measuring bit be provided with means for detecting the amount of vertical movement of the measuring bit at the measuring position.

(f) Embodiments of the Invention Next, examples will explain how the automatic wiring device according to the present invention is actually implemented. FIG. 3 is a longitudinal sectional view of the flatness detection section. Reference numeral 6 denotes a measuring bit which also serves as a bonding tool, and is made of a tapered cylinder, as shown in an enlarged view in FIG. The tip of the measurement bit 6 is provided with a cutting edge 6a that also serves as a cutter and wire holder. The measurement bit 6 is attached to the lower end of a cylindrical slider 8, and the slider 8 is inserted into a guide 9.
The guide 9 is provided with a stopper 10 on the lower side of the large diameter portion of the slider 8, and a return spring 11 for biasing is wound on the upper side of the large diameter portion of the slider 8. 9 is provided with a nut 12 for adjusting the spring pressure.

The guide 9 is screwed into a feed screw 13 rotated by a vertical drive motor M. In the frame 14,
A feed screw 13 is attached via a bearing, and a motor M is mounted. Further, a reflective photo sensor 16 is attached to the guide 9 which is driven up and down by a feed screw 13 via an attachment member 15 .

Next, the operation will be explained. The flatness measurement point on the printed circuit board 3 is selected in advance, and the measurement bit 6 is moved to the selected point. Then, at the selected measurement point, a drive motor M such as a pulse motor is operated to rotate the feed screw 13 and lower the guide 9. Since the slider 8 is pressed down by the biasing spring 11, when the guide 9 descends, the slider 8 and the measurement bit 6 also descend, and the measurement bit 6 comes into contact with the pad 4 of the printed circuit board 3. Even if the measuring bit 6 contacts the pad 4, the motor is further driven to lower the measuring bit 6. When the measuring bit 6 comes into contact with the pad 4, the measuring bit 6 cannot be lowered any further, but is moved against the biasing spring 11 by the guide 9.
can go down further. When the slider 8 descends a predetermined amount and rises above the position of the photo sensor 16, the fifth
As shown in the figure, the photo sensor 16 detects the upper end of the slider 8. Upon receiving this detection signal, motor M stops.

The vertical position of the guide 9 at the start of measurement, ie, the position at which the slider 8 starts descending, is always set constant. Therefore, the measuring bit 6 descends and comes into contact with the printed circuit board 3, and further descends to touch the photo sensor 16.
By detecting the amount of descent of the slider 8 until the slider 8 is detected at , the distance from the measurement point on the printed circuit board to the motor M or the feed screw 13 can be measured. If a pulse motor or the like is used as the drive motor M, the above distance can be easily measured by counting the number of drive pulses from when the slider 8 starts descending until the signal from the photo sensor 16 is input.

Such measurements are performed at each measurement point on the printed circuit board 3. If the position is raised, the amount of fall of the measurement bit 6 is small, and if it is a recessed position, the amount of fall of the measurement bit 6 is large, so the flatness of the printed circuit board 3 can be measured by measuring at multiple locations. can. Then, the address of each measurement point and the amount of fall of the measurement bit at each measurement point are stored in the memory of the control unit, and when bonding is performed as shown in Figure 2, the above measurement data is taken into account. The amount by which the bonding tool 6 and wire guide 5 are lowered is controlled. Within a certain distance from a certain measurement point, if the amount of descent is corrected based on the data of that measurement point, it is sufficient to measure only representative points, and there is no need to measure all bonding locations.

Note that although the bonding tool 6 itself is also used as a direct measurement bit, dedicated tools may be used for each.

(g) Effects of the Invention As described above, according to the present invention, the flatness of each point on the printed circuit board is measured by lowering the measuring bit and detecting the amount of movement thereof. Therefore, the flatness of the printed circuit board can be easily measured, and by controlling the amount of descent of the bonding tool based on this measurement data, it is possible to reliably connect discrete wires even on printed circuit boards with poor flatness. Bonding can be performed, improving the reliability of discrete wiring.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the wiring state of discrete wires on a printed circuit board, and FIG. 2 is a longitudinal cross-sectional view showing the state in which the discrete wires are bonded.
FIG. 3 is a longitudinal sectional view showing an embodiment of the flatness measuring section of the automatic wiring device according to the present invention, FIG. 4 is an enlarged side view of the tip of the measurement bit, and FIG. 5 is a side view showing the detection state of the slider. be. In the figure, 1 is a discrete wire, 3 is a printed circuit board, 4 is a pad, 5 is a wire guide, 6 is a bonding tool (measurement bit), 7 is a laser beam, 8 is a slider, 9 is a guide, 11 is a bias spring, 13 is a feed screw, 16 is a photo sensor, M
indicate the motors, respectively.

Claims (1)

[Scope of Claims] 1. A device for measuring the flatness of the surface of a printed circuit board in an automatic wiring device that automatically performs wiring by bonding discrete wires to the pads of a printed circuit board with a laser beam, comprising: Providing a measurement bit that is arranged perpendicular to the surface of the substrate and moves up and down by a motor, and forming the measurement bit into a cylindrical shape so that a laser beam passes through the measurement bit. The measurement bit is attached to a holder via a biasing means for biasing it in the downward direction, and the holder is connected to a motor via a vertical feeding mechanism, and An automatic wiring device characterized by comprising means for detecting the amount of movement.