JPS62293799A - Method of applying cream solder to printed board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] This invention is a printed circuit board in which a pattern of cream solder is printed at the component connection position in accordance with the wiring pattern on the printed circuit board. Concerning cream solder printing method.

[Conventional technology]

In recent years, as the pattern accuracy of printed circuit boards has improved, cream solder printing is also required to have higher accuracy.

Therefore, in order to improve the accuracy of cream solder printing on printed circuit boards, a specific pattern for positioning that corresponds to the cream solder printing mask and printed circuit board is prepared in advance, and the specific pattern position is determined by trial printing. A method of correcting the position of the printing mask by visually determining the deviation from the reference position, and a method of photographing the above-mentioned specific pattern position of the printed circuit board mounted at a position other than the printing position on the board transport device using an image recognition camera. Then, image processing is performed to calculate the deviation from the reference position, and after correcting the relative position between the printing mask and the printed circuit board by the amount of deviation, the printed circuit board is moved a predetermined distance to the printing position by the board transport device. There is a method in which the printed circuit board is transported and a pattern of a printing mask is printed on the printed circuit board using cream solder.

[Problem that the invention seeks to solve]

However, in the conventional method of printing cream solder on printed circuit boards, the former requires extremely high skill and several trial printings.

The latter method relies only on the mechanical precision of the transport device to determine the stopping position after the board is transported, so there is a problem in that the position of the printed circuit board that has been transported to the printing position may be misaligned.

The present invention provides a method of printing cream solder onto a printed circuit board, which can solve these conventional problems.

[Means for solving problems]

Therefore, in the cream solder printing method on a printed circuit board according to the present invention, a printing mask pattern is printed on a reference board in advance, and an image of a specific pattern position on the printed reference board is detected and stored as coordinate values. After that, the reference board is replaced with a printed circuit board, an image corresponding to the above-mentioned specific position of the wiring pattern is detected and its coordinate values are determined, and the deviation of the coordinate values of the corresponding patterns of the printed board and the above-mentioned reference board is determined. The above problem is solved by calculating the relative position of the printing mask and printed circuit board by the amount of deviation, and then printing the pattern of the printing mask on the printed circuit board with cream solder. It is.

[For production]

By doing the above, the reference board on which the printing mask pattern is printed in advance is replaced with a printed circuit board, and images of corresponding pattern positions are detected at the actual printing position and their coordinate positions are compared. Therefore, the pattern of the printing mask can be perfectly matched to the wiring pattern position of the printed circuit board on which cream solder is to be printed.

〔Example〕

Hereinafter, the present invention will be described based on specific embodiments with reference to the accompanying drawings.

FIG. 2 shows the entire cream solder printing machine to which the present invention is applied.

This cream solder printing machine 1 is a board transport device that inputs a reference board and printed circuit board to be printed at a predetermined position, transports them below the printing position, and discharges each board that has been printed with cream solder! ! 10. A substrate lifting device 20 that lifts and lowers the substrate transported below the printing position, a printing bag [30, a printing bag [30] that prints cream solder on the board lifted to the printing position by this substrate lifting device 20, A camera device that images and detects the pattern and the position of the specific pattern on the printed circuit board corresponding to this specific pattern! ! ! 40. This camera device [40] performs image processing on each pattern detected, determines each position as each coordinate value in the X, Y, and θ directions, and calculates the deviation thereof! i! (not shown), and an X fine adjustment device 50 for correcting the relative position of the cream solder printing mask and the printed circuit board by the calculated deviation. Y fine adjustment device 60. θ
It consists of a shaft fine adjustment device 70 and the like.

Here, the details of each of the above devices 10 to 70 are shown in FIGS. 3 and 4.
This will be explained with reference to the figures.

The substrate conveying device 10 includes a pair of belts 11. which convey the substrate in the X-axis direction indicated by the arrow. A substrate carry-in sensor 12 detects the presence or absence of a substrate to be carried to the left end side of the belt 11 in FIG. Transport motor 1
3. A fixed base that detects when a substrate moving in the direction of the arrow X comes below a printing mask (not shown) disposed in a recess 3a on a base 3 that can be slid in the Y-axis direction by a base driving device 2. Substrate sensor 14. As a result of the substrate detection by the fixed base substrate sensor 14, the substrate holder 21 (see Fig. 3) of the lifting device 20 is lifted up with the substrate mounted thereon, and the cylinder IS
A (see FIG. 3(b)) and a direction changing cam mechanism to project a positioning pin 15b and press the substrate against the transfer device reference surface 10a to position the substrate; a substrate positioning member 15;
It is constituted by a substrate ejection sensor 16 that detects the substrate moved to the ejection position by the conveyor belt 11 after cream solder printing and stops the conveyor motor 13.

Further, the elevating device 20 includes a board holder 21 and a screw 22 that are raised and lowered by the rotation of a trapezoidal screw 22, as shown in FIG.
The Z-axis motor 23 is loosely fitted to the top 22a of the trapezoidal screw 22 so as to be relatively rotatable, and rotates in the direction of rotation with the board holder 21 by means of a key and a keyway.
The axis fine adjustment member 71 is connected to a θ-axis stepping motor 72 that drives the θ-axis fine adjustment member 71 via a timing belt.
Together, they constitute a θ-axis fine adjustment device 70.

The board holder 21 is provided with a stopper 24 that can be moved up and down by a cylinder 24a so that the board can move up and down. In addition to allowing the movement to stop at a predetermined position below the printing mask, a position reference plate 73 is provided on the θ-axis fine adjustment member 71, and the position of the position reference plate 73 is determined by a θ-axis sensor 74 provided on a fixed part. By detecting this, the θ-axis stepping motor 72 is rotated in forward and reverse directions to correct the inclination of the substrate on the substrate holder 21.

The printing device 2!30 is operated by a stepping motor 31. a squeeze member 33 that squeezes the cream solder on the printing mask by moving in the Y-axis direction via the timing belt 32 and extends it onto the substrate fixed to the substrate holder 21 to print the pattern of the printing mask; Squeeze member 3
Squeeze cylinder 33. have.

The camera device 40 includes an imaging lens 41 as shown in FIG.
It consists of a camera stand 44 equipped with a CCD line sensor 42 and a light projection system 43 that illuminates the pattern on the board, and a ball screw mechanism 45 that moves this camera stand 44 in the X-axis direction. Send the data of the specific pattern detected by x to an image processing device (not shown)
,y.

Find and store the coordinate value of θ.

Note that the X fine adjustment device 50 and the Y fine adjustment device 60 each have stepping motors 51 and 61.

The X-axis adjusting table 53 and YI'II are provided so as to be movable in the X4illI and Y-axis directions within the plane of the pedestal 3 by rotating the screw portions 52 and 62 via a timing belt.
Each of the 11 IWR units 63 is slightly moved to correct the position of the printing mask in accordance with the amount of deviation of the printed circuit board.

Next, a method of printing on a printed circuit board using the cream solder printing machine 1 configured as described above will be explained step by step in accordance with the process diagram of FIG. 1 with reference to FIGS. 2 to 4.

First, the pedestal 3 is moved from the state shown in FIG. 2 to the left end in the figure, and the pattern frame jig 5 with the printing mask 4 attached is placed on the pedestal 3 as shown in FIG. 1(a). Recessed portion 3a
cream solder 6 is set on this pattern frame jig 5.

Next, when the reference board 7 without a wiring pattern is placed onto the belt 11 which is in a stationary state as shown in FIG. While being transported in the direction of the arrow 4, the cylinder 24a provided on the substrate pedestal 21 is operated and the stopper 24 protrudes.

When the reference substrate 7 comes below the cream solder printing position, its end surface comes into contact with the protruding stopper 24 and is stopped, and only the belt 11 moves by sliding on the lower surface of the reference substrate 7.

When the fixed base board sensor 14 detects this at this position,
The Z-axis motor 23 rotates and raises the substrate pedestal 21.

As the substrate holder 21 rises, the reference substrate 7 on the belt 11
is mounted on the board holder 21, and when it rises to the first position and stops, the cylinder ISa of the board positioning member 15
is activated to project the positioning pin 15b and press the reference board 7 against the reference surface 10a (see FIG. 3(b)) to position it.

In this state, after the reference substrate 7 is attracted and fixed to the substrate holder 21, the stopper 24 and the positioning pin ISb are retracted, and the transport motor 13 is stopped.

Here, the Z-axis motor 23 is further rotated to move the board holder 2.
1 to the second position, and after holding the reference board 7 on the board holder 21 in a position where it is almost in contact with the printing mask board 4 fixed to the pedestal B, move the printing device f130 to the right in FIG. Then, in the process shown in FIG. 1(b), the pattern of the printing mask 4 is printed on the reference substrate 7 with cream solder 6.

When the printing of the reference board 7 is completed, the Z-axis motor 23 rotates in reverse to lower the board holder 21 to the third position.

The pedestal driving device 2 starts, the pedestal 3 retreats a predetermined distance in the Y-axis direction, and then stops.

Here, as shown in FIG. 1(c), the camera stand 44 moves in the X-axis direction, and the camera device 40 scans a specific cream solder pattern 7a on the reference board 7.
The image detection signal is subjected to image processing and arithmetic processing to determine the coordinate values x, l YO* θ0 of the specific pattern and are stored.

Thereafter, the camera stand 44 returns to its origin, releases the reference board 7 from adsorption, and further reverses the Z-axis motor 23 to lower the board holder 21 and mount the reference board 7 on the belt 11. When the fixed base board sensor 14 detects this, the transport motor 13 rotates to transport the reference board 7 in the discharge direction, and the board holder 21 further descends to the origin.

When the reference substrate 7 arrives at the unloading position, the substrate unloading sensor 1
6 detects this and stops the transport motor 13, and at this stage the printing and image processing steps for the reference substrate 7 are completed.

Next, the printed circuit board 8 that will become a product is put into the transport device 10, and the printed circuit board 8 on the board holder 21 is raised to the third position and stopped in the same manner as the reference board 7.
As shown in Figure (d), the camera stand 44 moves from the origin in the X-axis direction, and the camera device 4 moves the position of the pattern 8a on the printed circuit board 8 corresponding to the predetermined pattern position of the reference board 7.
0, and the image detection signal is subjected to image processing and arithmetic processing to obtain the coordinate values x1. y,.

After determining θ1, the camera stand 44 is returned to the origin.

The coordinate values XI ty, t θ are compared with the coordinate values x, l'yol θ0 of a specific pattern position on the reference substrate, and the deviation amounts ΔX, ΔY, and Δθ are calculated, respectively. .

Regarding the amount of deviation, as shown in FIG. 1(e), the θ-axis motor 72 of the θ-axis fine adjustment device 70 is rotated in the required direction, and the board holder 21 is rotated by the angle Δθ. Correcting the tilt and regarding the deviation amounts ΔX and ΔY,
X fine adjustment device so.

The stepping motors 51 and 61 of the Y fine adjustment device 60 are rotated, and the X fine adjustment 53 and the Y fine adjustment 63 of the pedestal 3 are slightly moved to correct the position of the printing mask plate fixed to the pedestal O.

In parallel with this, the pedestal 3 is moved to the left from the position shown in FIG. 2 and returned to the origin, and the board holder 21 is raised to the second position, and then printing is performed in the process shown in FIG. 1(f). The printing mask 4 is placed on the printed circuit board 8 by moving the device 30 in the Y-axis direction.
Print the pattern with cream solder 6.

When printing is finished, the board holder 21 is lowered to the first position and
Fine adjustment fi! 50. The Y fine adjustment device 60 and the θ-axis fine adjustment device 70 each return to their origin, the suction of the product substrate 8 is released, and the substrate holder 21 further descends to the origin.

As a result, the printed printed circuit board 8 is mounted on the belt 11, and when the fixed base board sensor 14 detects this, the transport motor 13 rotates to transport the printed circuit board 8 to the ejection position, and the ejection board sensor 16 detects this. is detected, the conveyance motor 13 is stopped, and the cream solder printing process for the first product board 8 is completed.

For the second and subsequent printed circuit boards, the image of the pattern position of the printed circuit board 8 corresponding to the specific pattern 7a of the reference board 7 is detected each time, and the coordinate values of that pattern are used as the coordinate values of the pattern 7a of the reference board 7. Cream solder printing is performed after performing position correction compared to .

In this embodiment, regarding the positional deviation between the printing mask 4 and the printed circuit board 8 corresponding to the reference substrate 7, Δθ, the printed circuit board 8 side is set to ΔX.

Regarding ΔY, the printing mask 4 side was slightly moved, but the reverse may also be used, and Δθ.

There is no problem even if ΔX and ΔY are all corrected on the printed circuit board 8 side or the printing mask 4 side.

〔Effect of the invention〕

As described above, in the cream solder printing method on a printed circuit board according to the present invention, a printing grid pattern is printed on a reference board in advance, and an image of a specific pattern position on the reference board at the printing position is printed. The image of the corresponding pattern position on the printed circuit board at the same position is detected, the deviation of each coordinate value is calculated, and the relative position between the printing mask and the printed circuit board is corrected by the deviation. Unlike the method of transporting the printed circuit board to the printing position after correcting the relative position between the printed circuit board and the printing mask at a position other than the printing position, there is no risk of transport errors, and the accuracy of cream solder printing is greatly improved. can be improved.

In addition, as the specific corresponding pattern of the reference board and the printed circuit board, it is possible to use a pattern that is commonly used for both, such as a land for connecting lead wires of electronic components, among the patterns that are actually used. This eliminates the need to additionally print patterns dedicated to image processing.

[Brief explanation of the drawing]

1(a) to 1(f) are explanatory diagrams showing the main steps of the present invention; FIG. 2 is a perspective view showing the entire cream solder printing machine to which the present invention is applied; 4(b) is a side view and a plan view of essential parts showing the substrate lifting device and the θ-axis correction device, and FIGS. 4(a) and 4(b) are a front view and a side view schematically showing the camera device.1 ...cream solder printing machine 3...pedestal 4...
・Printing mask 5...Pattern frame jig 6...
・Cream half 1) 7... Reference board 8... Printed circuit board 10... Board transport device 20... Board lifting device 30... Printing device 40... Camera device 50... X fine adjustment Device 60...Y fine adjustment device 70...θ axis fine adjustment device Fig. 1 Fig. 3 Fig. 4 (b) -12

Claims (1)

[Claims] 1. Print a printing mask pattern on a reference board in advance, detect an image of a specific pattern position on the printed reference board and store it as a coordinate value, then replace the reference board with a printed circuit board, and An image corresponding to the specific position on the wiring pattern is detected, its coordinate values are determined, a deviation between the coordinate values of the corresponding patterns on the printed circuit board and the reference board is calculated, and a printing mask is applied by the amount of the deviation. 1. A method of printing cream solder on a printed circuit board, comprising correcting the relative position between the printed circuit board and the printed circuit board, and then printing a pattern of a printing mask on the printed circuit board with cream solder.