JP2000269695A - Method and device for adjusting printed-wiring board surface height - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for adjusting printed-wiring board surface height, that can eliminate surface height adjustment errors caused by the dimensional tolerance of a printed-wiring board and can solve a problem where measurement and height adjustment differ due to warpage of the printed-wiring board, when registering the printed-wiring board in a printing, coating, or mounting machine. SOLUTION: When a printed-wiring board 5 is to be carried to a printing, coating, or mounting machine by a carrier belt 4 and a carrier rail 3, the plate thickness of the printed-wiring board 5 to be carried in is measured by plate-thickness measuring instrument 11. The plate thickness of the printed-wiring board 5 passing through the plate-thickness measuring instrument 5 is measured along its entire length, the measurement value is inputted to an operation control circuit 12, and the average value of the plate thickness is calculated. The operation control circuit 12 outputs a pulse signal, based on the difference between a calculation average value and a setting value to a pulse motor 10 for control. A pedestal 7 moves vertically by the rotation of a ball screw 9 to match and controls the surface height of the printed- wiring board 5 to a reference surface 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for adjusting the surface height of a printed wiring board when performing printing, coating, mounting, or the like.

[0002]

2. Description of the Related Art When printing, coating, or mounting on a printed wiring board, it is necessary to match the surface height of the printed wiring board with a reference plane for printing, coating, or mounting. FIG. 4 shows a configuration of a conventional apparatus for adjusting the surface height. A printed wiring board 5 is loaded vertically by a transport rail 3 and a transport belt 4 onto a paper surface and positioned at a required position. At this time, the height of the printed wiring board 5 is adjusted by raising and lowering the pedestal 7 and holding the lower surface of the printed wiring board 5 with backup pins or plates 6. The pedestal 7 is guided by a shaft 8, and the ball screw 9 is screwed up and down. The ball screw 9 is rotated by driving a pulse motor 10 to adjust the height of the pedestal 7. As a result, the printed wiring board 5 is connected to the backup pins 6.
To adjust the level so that the surface height of the printed wiring board 5 matches the reference surface 1 for work such as printing. For the level adjustment, as shown in FIG. 5, the thickness data of the printed wiring board 5 is input, the pulse motor 10 is driven according to the data value, the ball screw 9 is rotated, and the height is adjusted. Then, screen printing or surface mounting is performed with the adjusted height kept as it is.

[0003] For example, a case where cream solder printing is performed on the printed wiring board 5 will be described. First, the printed wiring board 5 is carried into a printing machine. Then, after positioning and fixing by the pedestal 7, the ball screw 9 is rotated by driving the pulse motor 10, and the surface of the printed wiring board 5 is raised or lowered to just below the reference plane 1 by the pedestal 7 and the backup pin 6. A screen plate (not shown) is arranged on the reference plane 1. Thereafter, the squeegee is lowered, and the print head is moved to print the cream solder on the printed wiring board. When printing is completed, the pedestal 7 is lowered to lower the printed wiring board 5 away from the screen plate, and the squeegee is raised. Thereafter, the pedestal 7 is rapidly lowered, the printed wiring board 5 is carried out of the printing machine, and printing is completed.

[0004]

The above-mentioned conventional configuration has the following problems.

(1) When a rigid printed circuit board having a thickness of 0.8 mm and 4 layers to 6 layers is used, the dimensional tolerance of the thickness is as large as ± 0.1 mm. The printed wiring board 5
In some cases, a gap 2 corresponding to a variation in dimensional tolerance may occur between the reference surface 1 and the reference surface 1.

(2) If the gap 2 is large at the time of printing, the printing amount increases, and if the gap 2 is small, blurring occurs. In addition, poor threading at the time of application, component bounce at the time of mounting, and component cracking due to excessive pushing may occur.

(3) The printed wiring board is warped. Conventional methods include measuring the surface height of the board and adjusting the table height accordingly.However, due to the warpage of the printed wiring board, the method of measuring the surface height position requires a printing squeegee or blade. In such a case, the warpage is corrected when pressed, so that the measurement and the adjustment have different heights, and there is a problem that the printing condition is different from a predetermined value.

In addition, a method described in Japanese Patent Application Laid-Open No. 9-76455 is known. In this method, the position of the upper surface of the printed wiring board is measured by a camera in a free state without pressing the printed wiring board. In this case, since the thickness of the printed wiring board and the height of the warped and deformed surface are measured, the warpage corrected by the pressure of the squeegee when applying the cream solder, the board reference to the stage surface, The change of the holding posture due to the pressing of the surface cannot be considered. Conventionally used substrates generally have a thickness of about 2 mm and are difficult to deform, but for the latest 6-layer or more built-up substrates etc., the base material became a thin film or epoxy It is easily deformed, and changes in the pattern of the copper foil pattern of the intermediate layer and the thickness of the adhesive material are notably reflected in the substrate thickness, and it is also deformed by squeegee pressure, so the surface of the printed wiring board There is a problem that it is inappropriate to determine the posture and height during squeegee from the height.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the problems of the prior art, such as variations in print thickness due to variations in the tolerance of printed wiring boards, variations in the amount of coating, defects in which mounting shortages occur, and the like. It is an object of the present invention to provide a printed wiring board surface height adjusting method and apparatus which can solve the problem of warpage which cannot be solved by the printed wiring board surface height measuring method.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is to provide a means for measuring the thickness of a printed wiring board which is fed to a printing, coating or mounting machine, and to measure the thickness of the printed wiring board over the entire length of the printed wiring board from the measured thickness. This is achieved by providing means for calculating the average value of the thickness, and means for adjusting the height so that the surface of the printed wiring board matches the reference surface for printing, coating, or mounting based on the average value of the thickness. .

The above means measures the thickness of the printed wiring board conveyed and supplied over the entire length when adjusting the surface height of the printed wiring board on which printing, coating or mounting is performed.
The average value of the thickness of the printed wiring board is obtained from the measured value,
Based on the average value, height adjustment control is performed so that the surface of the printed wiring board matches the reference plane. According to this, it is possible to solve the problem of the variation in the thickness tolerance of the printed wiring board and the error of the height adjustment due to the warpage.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. The printed wiring board 5 is mounted on a transport belt 4, guided and transported by a transport rail 3, and carried into a printing machine, a coating machine, a mounting machine, and the like. The conveyed printed wiring board 5 is guided on a backup pin or plate 6 of a pedestal 7 and positioned and controlled. Thereafter, the pedestal 7 is moved up and down and supported by the backup pin or the plate 6 to adjust the height. The pedestal 7 is vertically moved by a ball screw 9 guided and screwed by a shaft 8. The ball screw 9 is rotated by driving the pulse motor 10 to adjust the height of the pedestal 7.

The printed wiring board 5 carried in by the transport belt is disposed in the middle of the left and right transport rails 3 and passes through a thickness measuring device 11 which is vertically opposed with the printed wiring board 5 interposed therebetween. As a result, the printed wiring board 5 is
, The thickness of the facing portion is measured, and the thickness of the printed wiring board 5 is measured over the entire length of the printed wiring board 5 which is conveyed and passed. The measured values of the thickness measuring device 11 are sequentially input to the arithmetic and control circuit 12. The arithmetic and control circuit 12 calculates the average value of the board thickness by adding the inputted board thickness measurement values and calculating from the total length of the printed wiring board 5, and outputs a control pulse signal to the pulse motor 10. The obtained average thickness may be compared with a set value corresponding to the thickness data of the printed wiring board registered first, and a control pulse signal corresponding to the difference may be output to the pulse motor 10.

Although the height of the pedestal 7 is set to a height corresponding to the thickness data of the printed wiring board 5 by initial setting,
If there is a difference between the detected average value and the set value, the arithmetic control circuit 1
2 outputs a control pulse signal, so that the pulse motor 1
Numeral 0 rotates according to the signal and drives the ball screw 9 to control the pedestal 7. By controlling the height of the pedestal 7, the positioning can be adjusted so that the surface height of the printed wiring board 5 accurately matches the reference surface 1 on which printing, coating, or mounting is performed.

FIG. 2 shows a cream solder printing apparatus, in which 13 is a print head having a squeegee 14,
The squeegee 14 moves by pressing against the printing screen plate 15. Reference numeral 16 denotes cream solder supplied on the screen plate 15. The printed wiring board 5 is carried into the printing machine in the previous process, and is positioned on the pedestal 7. After the pedestal 7 is driven by the pulse motor 10, the height of the pedestal 7 is controlled according to the measured average thickness of the printed wiring board 5. The height is adjusted so that the upper surface of the printed wiring board 5 is located directly below the printing screen plate 15. Thereafter, the squeegee 14 is lowered, and the cream head 1 is moved by the squeegee 14 by the movement of the print head 13.
6 is printed on the printed wiring board 5. When printing is completed, the pedestal 7 descends under the control of the pulse motor 10 and descends until the printed wiring board 5 separates from the screen plate 15. Thereafter, the squeegee 14 is raised and the pedestal 7 is lowered, and the printed wiring board 5 is carried out of the printing press.

In a coating and mounting machine other than printing, a printed wiring board is loaded into a mechanical device, positioned,
The steps of height adjustment, processing, and unloading are repeated.

FIG. 3 is a flowchart showing a case where the loading, positioning adjustment, printing, coating, or mounting of the printed wiring board 5 is performed by automatic operation. First, the automatic operation of the printing press is started (S1). The printed wiring board 5 is carried into the printing machine by the conveyor belt 4. Printed wiring board 5 when loading
Is passed through the thickness measuring device 11 to measure the thickness (S2). The measured values of the thickness measuring device 11 are sequentially input to the arithmetic control circuit 12 and added. When the measured values over the entire length of the printed wiring board 5 are input, the arithmetic control circuit 12 calculates the average thickness (S3). ).

Then, the arithmetic and control circuit 12 compares the obtained average value with the set value based on the preset thickness data and outputs a pulse signal corresponding to the difference signal to the pulse motor 10 (S4). The pulse motor 10 rotates in accordance with the input signal, rotates the ball screw 9 to control the pedestal 7, and adjusts the height of the printed wiring board 5 carried by the backup pin 6 (S5). Thereby, the printed wiring board 5
Is adjusted to a height that matches a reference surface on which printing is to be performed, and printing or component mounting is performed on this reference surface by a printing squeegee or screen (S6). When printing or mounting is completed, the pedestal 7 is lowered and the squeegee is raised to carry out the printed wiring board 5 (S7). Further, the next printed wiring board 5 is carried in, and steps (S2 to S7) are repeated to perform printing.

The illustrated thickness measuring device 11 is a non-contact type, and includes an infrared sensor, an LED sensor, a laser sensor,
An ultrasonic sensor or the like is used. This is the detection sensor 11
Are arranged vertically facing each other with the printed wiring board 5 interposed therebetween, and a reference plane is provided by the two sensors 11 to measure the difference in distance between the printed wiring boards 5, or the thickness of the printed wiring board 5 is measured by a light emitting / receiving sensor. For example, a method of directly measuring the plate thickness based on a change in the light amount due to the difference is used.

A device for measuring the thickness of the printed wiring board 5 by contact is used. A digital meter is mounted on the upper surface of the printed wiring board 5 with the lower surface of the printed wiring board 5 being transported as a reference (zero point). A method of measuring the thickness of a printed circuit board, a method of setting a digital meter on each of the upper and lower surfaces of the printed wiring board 5, and adding the scale of the upper surface and the scale of the lower surface to measure the thickness of the printed wiring board 5 is used.

The measured value of the sheet thickness is calculated by the arithmetic and control circuit 12.
To calculate the average value of the total length of the printed wiring board. Then, a control pulse signal corresponding to the plate thickness average value is output, and the pulse motor 10 is driven. In this way, the height of the pedestal 7 is controlled, and the height of the printed wiring board 5 is controlled to coincide with the reference plane. Since this height control is performed based on the measurement of the thickness of the printed wiring board 5, errors due to variations in the tolerance of the thickness can be removed. In addition, the printed wiring board 5
Since the height is controlled by the average value of the thickness of the printed wiring board, it is possible to perform the height adjustment with high accuracy by removing the error of the height adjustment due to the warpage of the printed wiring board 5, and print, apply,
It is possible to accurately match the reference surface on which the mounting is performed.

In the above embodiment, the control device for adjusting the height of the printed wiring board is provided with a ball screw and a pulse motor. However, a microswitch, a magnetism, an optical sensor, an encoder and the like are used as sensors.
A control device using a hydraulic cylinder, a servomotor, or the like can be used.

[0024]

As described above, according to the present invention, the thickness of a printed wiring board to be transported is measured, and the average value of the thickness is calculated. Since the adjustment is performed, the height adjustment error due to the variation of the tolerance of the printed wiring board can be eliminated, and the effect that the measurement due to the warpage of the printed wiring board and the height adjustment are different can be easily solved. is there.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a height adjustment device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a printing apparatus according to an embodiment of the present invention.

FIG. 3 is a flowchart illustrating a control procedure according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional device.

FIG. 5 is a flowchart showing a control procedure of a conventional apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reference surface, 2 ... Gap, 3 ... Transport rail, 4 ... Transport belt, 5 ... Printed wiring board, 6 ... Backup pin or plate, 7 ... Pedestal, 8 ... Shaft, 9 ... Ball screw,
10: pulse motor, 11: thickness measuring instrument, 12: arithmetic control circuit, 13: print head, 14: squeegee, 15: screen plate, 16: cream solder.

Claims (2)

[Claims] 1. The thickness of a printed wiring board conveyed and supplied is measured over the entire length, and the average value of the thickness of the printed wiring board is determined from the measured values. A method for adjusting the surface height of a printed wiring board, wherein the height is adjusted to match the surface. 2. A means for measuring a thickness of a printed wiring board conveyed and supplied to a printing, coating or mounting machine, and a means for calculating an average value of the thickness over the entire length of the printed wiring board from the measured thickness. And a means for adjusting the height so that the surface of the printed wiring board matches the reference surface for printing, coating, or mounting based on the average value of the thickness of the printed wiring board.