Electronic component mounting method and mounting apparatus

The substrate recognition time is shortened, and the productivity is enhanced. This is an electronic component mounting method for mounting a plurality of electronic components on a substrate by using a plurality of moving tables. Each moving table of the plurality of moving tables has a mounting head for picking up and transferring each electronic component, and a camera for recognizing the substrate. The mounting method includes the steps of (a) taking a calibration substrate having a reference mark for position calibration by the camera, and obtaining a position calibration data intrinsic to each moving table having the camera, (b) taking the substrate by only one of the cameras prior to mounting of each electronic component, and recognizing the position of the substrate, and (c) picking up each electronic component by each mounting head, and mounting the electronic component on the substrate. The step of mounting each electronic component on the substrate includes a step of controlling the position of the moving table on the basis of the substrate position recognition result and the position calibration data.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an electronic component mounting method of mounting electronic components on a substrate, and an electronic component mounting apparatus.

BACKGROUND OF THE INVENTION

An electronic component mounting apparatus comprises a moving table for moving a mounting head which picks up an electronic component from an electronic component feeder onto an object substrate. As such moving table, an orthogonal coordinate system table for making linear motions in the X, Y, Z directions is widely employed. This moving table generally comprises a substrate recognition camera which moves together with the mounting head. By taking the substrate by this camera, the position of the substrate is detected, and the position is adjusted when mounting the electronic component on the basis of the result of position detection.

Other conventional electronic component mounting apparatus comprises a plurality of moving tables for the purpose of enhancing the mounting efficiency, and by using a plurality of mounting heads for one substrate, electronic components are mounted simultaneously by parallel operation. In such conventional mounting apparatus, each one of the plurality of moving tables has a substrate recognition camera. Prior to mounting of electronic components, the object substrate is recognized by a plurality of cameras of the plurality of moving tables.

In such conventional method, however, one substrate must be recognized plural times, and the time of moving the camera to the recognition point on the substrate is duplicated. As a result, the cycle time of the entire mounting process is longer, and the productivity is lowered:

It is hence an object of the invention to present an electronic component mounting method capable of shortening the cycle time and enhancing the productivity.

SUMMARY OF THE INVENTION

The electronic component mounting method of the invention is a method of mounting a plurality of electronic components on a substrate by using a plurality of moving tables. Each moving table of the plurality of moving tables has a mounting head for picking up and transferring each electronic component, and a camera for recognizing the substrate. The mounting method comprises:

(a) a step of taking a substrate for calibration having a reference mark for position calibration by the camera, and obtaining position calibration data intrinsic to each moving table having the camera,

(b) a step of taking the substrate by only one of the cameras prior to mounting of each electronic component, and recognizing the position of the substrate, and

(c) a step of picking up each electronic component by each mounting head, and mounting the electronic component on the substrate.

The step of mounting each electronic component on the substrate includes a step of controlling the position of the moving table on the basis of the substrate position recognition result and the position calibration data.

The electronic component mounting apparatus of the invention comprises:

(b) a first moving table and a second moving table installed on the base, in which the first moving table and second moving table are movable on the base, the first moving table has a first mounting head and a first camera, the second moving table has a second mounting head and a second camera, and the first mounting head and second mounting head have a function of picking up and transferring a plurality of electronic components,

(c) position calibration data acquiring means for recognizing the position of the first moving table and second moving table, and calibrating the position of the first moving table and second moving table,

(d) position recognizing means for recognizing the position of the substrate mounted on the base, in which the position recognizing means is recognized when taken by the first camera only,

(e) controlling means for controlling the position of the first moving table and second moving table on the basis of the position recognizing means and position calibration data acquiring means, and

(f) driving means for driving the first moving table, second moving table, first mounting head and second mounting head.

In this configuration, the cycle time is shortened. As a result, the productivity is enhanced.

REFERENCE NUMERALS

3 a Recognition mark

3 b Reference mark

4 A First moving table

4 B Second moving table

5 A First Y-table

6 A First X-table

7 A First mounting head

7 B Second mounting head

8 A First camera

8 B Second camera

9 M Reference position recognition mark

11 Position calibration data acquisition unit

12 Substrate position recognition unit

13 Control unit

14 Drive control unit

DETAILED DESCRIPTION OF THE INVENTION

An electronic component mounting method in an embodiment of the invention is a method of mounting electronic components on a single substrate by using a plurality of moving tables. Each moving table of the plurality of moving tables has a mounting head for picking up and transferring electronic component, and a camera for recognizing the substrate on which the electronic component is mounted.

The mounting method comprises a step of taking a substrate for calibration having a reference mark for position calibration by the camera, and obtaining position calibration data intrinsic to the moving table having the camera, a step of taking the substrate by any one of the cameras prior to mounting of electronic components, and recognizing the position of the substrate, and a step of picking up each electronic component by each mounting head of the plurality of moving tables, and mounting on the substrate.

This mounting step includes a step of controlling the position of the moving table on the basis of the substrate position recognition result and the position calibration data intrinsic to the moving table.

An electronic component mounting method in other embodiment of the invention comprises:

(a) a step of preparing a base, and a first moving table and a second moving table installed on the base, in which the first moving table and second moving table are movable on the base, the first moving table has a first mounting head and a first camera, the second moving table has a second mounting head and a second camera, and the first mounting head and second mounting head pick up and transfer a plurality of electronic components,

(b) a step of acquiring position calibration data intrinsic to each moving table of the first moving table and second moving table,

(c) a step of conveying a substrate onto the base,

(d) a step of recognizing the position of the substrate by at least one camera of the first camera and second camera, and acquiring the position recognition data,

(e) a step of controlling the position of the first moving table and second moving table on the basis of the position calibration data and position recognition data, and

(f) a step of picking up the plurality of electronic components by the first mounting head and second mounting head, and mounting on the substrate.

Preferably, the following calibration is provided.

The step of acquiring the position recognition data is a step of recognizing the position of the substrate by only one camera of the first camera and second camera.

The step of acquiring the position calibration data includes:

(1) a step of mounting a substrate for calibration having a reference mark on the base, and

(2) a step of taking the reference mark by at least one camera of the first camera and second camera, and acquiring the position calibration data for calibrating the position deviation.

The reference mark has a plurality of reference marks, and the step of acquiring the position calibration data includes a step of taking all of the plurality of reference marks by the first camera, and recognizing the position deviation of each reference mark of the plurality of reference marks.

The step of acquiring the position recognition data includes a step of moving the first moving table, and recognizing the position of the recognition mark set on the substrate by the first camera.

The recognition mark has a plurality of recognition marks, and the first camera recognizes each recognition mark of the plurality of recognition marks sequentially.

The step of acquiring the position recognition data includes a step of acquiring the position recognition data by moving the first moving table, and recognizing the position of the recognition mark set on the substrate by the first camera, and the step of mounting the plurality of electronic components on the substrate includes a step of mounting the electronic component on the substrate by the first mounting head, on the basis of the position calibration data and position recognition data of the first moving table, and a step of mounting the electronic component on the substrate by the second mounting head, on the basis of the same position recognition data as the position calibration data and position recognition data of the second moving table.

The step of acquiring the position calibration data includes:

(1) a step of acquiring the position calibration data for calibrating the position deviation, by mounting a substrate for calibration having a reference mark on the base, and taking the reference mark by at least one camera of the first camera and second camera, and

(2) a step of acquiring further position calibration data for correcting position deviation due to temperature changes of the first moving table and second moving table, by taking a position recognition mark set on the base by at least one camera of the first camera and second camera.

In this configuration, in recognition of substrate by the camera conducted prior to the mounting step of electronic components on the substrate by a plurality of mounting heads, the substrate is recognized by one camera only of the plurality of cameras, and the plurality of mounting heads are positioned on the basis of the result of this recognition. Therefore, the substrate recognition time can be shortened.

Referring now to the drawings, exemplary embodiments of the invention are described below.

FIG. 1 and FIG. 2 ( a ) are plan views of an electronic component mounting apparatus in an exemplary embodiment of the invention. FIG. 2 ( b ) shows an image diagram for substrate recognition of an electronic component mounting apparatus in an exemplary embodiment of the invention. FIG. 3 is a flowchart of electronic component mounting process in an exemplary embodiment of the invention. FIG. 4 is a schematic view of an electronic component mounting apparatus in an exemplary embodiment of the invention.

Referring first to FIG. 1 and FIG. 4 , the structure of the electronic component mounting apparatus is explained.

In FIG. 4 , the electronic component mounting apparatus comprises a base 1 , a first moving table 4 A, a second moving table 4 B, a position calibration data acquisition unit 11 , a substrate position recognition unit 12 , a control unit 13 , and a drive control unit 14 .

The position calibration data acquisition unit 11 recognizes the position of the first moving table 4 A and second moving table 4 B, and calibrates the position of the first moving table 4 A and second moving table 4 B. The substrate position recognition unit 12 recognizes the position of a substrate 3 mounted on the base 1 . The control unit 13 controls the position of the first moving table 4 A and second moving table 4 B, on the basis of the substrate position recognition unit 12 and position calibration data acquisition unit 11 . The drive control unit 14 drives the first moving table 4 A, second moving table 4 B, first mounting head 7 A and second mounting head 7 B.

The first moving table 4 A and second moving table 4 B are movable on the base 1 . The first moving table 4 A has a first mounting head 7 A and a first camera 8 A. The second moving table 4 B has a second mounting head 7 B and a second camera 8 B. The first mounting head 7 A and second mounting head 7 B have a function of picking up and transferring a plurality of electronic components. The substrate position recognition unit 12 is recognized when taken by the first camera 8 A only,

The position calibration data acquisition unit 11 has a substrate for calibration 3 e set on the base 1 . The substrate for calibration 3 e has a reference mark 3 b (FIG. 2 ( a )). The first camera 8 A and second camera 8 B recognizes the reference mark 3 b . The position calibration data acquisition unit 11 has a reference position recognition mark 9 M (FIG. 2 ( a ))set on the base 1 , and a substrate for calibration 3 e set on the base 1 . The first camera 8 A and second camera 8 B recognizes the reference mark 3 b . At least one camera of the first camera 8 A and second camera 8 B takes the reference position recognition mark 9 M, thereby acquiring further position calibration data for correcting position deviation due to temperature changes of the first moving table 4 A and second moving table 4 B.

In FIG. 1 , a conveying path 2 is disposed on the base 1 . The conveying path 2 conveys the substrate 3 delivered from the preceding process, and positions it at the electronic component mounting position. At both sides of the conveying path 2 , the first moving table 4 A and second moving table 4 B are disposed. The first moving table 4 A and second moving table 4 B have an identical structure.

The first moving table 4 A has a first Y-table 5 A and a first X-table 6 A. The first mounting head 7 A is mounted on the first X-table 6 A. The second moving table 4 B has a second Y-table 5 B and a second X-table 6 B. The second mounting head 7 B is mounted on the second X-table 6 B. By driving the first moving table 4 A and second moving table 4 B, the first mounting head 7 A and second mounting head 7 B move horizontally, and the first mounting head 7 A and second mounting head 7 B pick up electronic components from an electronic component feeder (not shown), and transfer and mount them on the substrate 3 .

A first camera 8 A is mounted on the first X-table 6 A. A second camera 8 B is mounted on the second X-table 6 B. The first camera 8 A moves integrally with the first mounting head 7 A. The second camera 8 B moves integrally with the second mounting head 7 B. By driving the first moving table 4 A and second moving table 4 B, the first camera 8 A and second camera 8 B are moved on the substrate 3 . When the first camera 8 A takes the recognition marks 3 a provided at diagonal positions of the substrate 3 , the position of the substrate 3 is recognized. On the basis of the result of this position recognition, position deviation of the substrate 3 is detected. When mounting electronic components, this position deviation is corrected, and the first moving table 4 A and second moving table 4 B are driven.

Referring next to FIG. 2 ( a ) and FIG. 2 ( b ), the calibration for correcting the individual positioning errors of the first moving table 4 A and second moving table 4 B is explained.

As shown in FIG. 2 ( a ), the first moving table 4 A has an intrinsic orthogonal coordinate system X 1 -Y 1 . The second moving table 4 B has an intrinsic system X 2 -Y 2 . However, due to mechanical error in coupled state of the first X-table 6 A and first Y-table 5 A, the intersection angle 1 of the X-axis and Y-axis is not a complete right angle. Similarly, due to mechanical error in coupled state of the second X-table 6 B and second Y-table 5 B, the intersection angle 2 of the X-axis and Y-axis is not a complete right angle. Moreover, the first X-table 6 A, second X-table 6 B, first Y-table 5 A, and second Y-table 5 B individually have pitch errors of ball screws or fluctuation in linearity of the guide unit.

Accordingly, the position indicated on the control data and the position of the mounting head actually driven and moved by the moving table do not always coincide with each other precisely. As a result, a position deviation occurs between the mounting position when mounting the electronic components and the mounting point indicated by the data. This position deviation is not constant, and the position deviation differs depending on each position in the moving range of the moving tables. Therefore, when mounting electronic components on a substrate by moving the mounting heads by a plurality of moving tables, a different position deviation occurs at each position on the substrate in each moving table.

To correct these position deviations, calibration is done. In the calibration, a calibration substrate (position calibration substrate) 3 e is used. The calibration substrate 3 e is manufactured according to the standard so as not to cause positioning error. On the surface of the calibration substrate 3 e , as shown in FIG. 2 ( a ), a plurality of reference marks 3 b are disposed in a lattice form at specified precision. First, driving the first moving table 4 A, the first camera 8 A is moved onto the calibration substrate 3 e positioned at the specified position. Taking each reference mark 3 b sequentially, the position of each reference mark 3 b is recognized.

At this time, the move of the first camera 8 A is controlled so that the origin O of the optical coordinate system on the control data may coincide with the center of the reference mark 3 b . However, as a result of position recognition by the camera, the origin O does not always coincide with the center of the reference mark 3 b due to mechanical error of the first moving table 4 A. FIG. 2 ( b ) shows the image diagram when the position is recognized by referring to one reference mark 3 bn of the plurality of reference marks 3 b . Herein, by position recognition, with respect to the reference mark 3 bn , the position deviations of xn, yn from the origin O of the optical coordinate system are detected. The reference mark 3 bn is the central coordinates (Xn, Yn) in the machine coordinate system.

That is, when mounting an electronic component near the coordinates (Xn, Yn) in the machine coordinate system, the substrate position recognized by the first camera 8 A must be further corrected by xn and yn. Therefore, upon start of assembling finishing process of the electronic component mounting apparatus, by determining the position deviation amount in all reference marks of the plurality of reference marks 3 b , the position calibration data for calibrating the position deviation intrinsic to the coordinate system X 1 -Y 1 of the first moving table 4 A may be obtained.

Such calibration is conducted also on the second moving table 4 B, in the same manner as in the first moving table 4 A, and position calibration data for the second moving table 4 B is obtained. That is, driving the second moving table 4 B, the second camera 8 B is moved onto the calibration substrate 3 e positioned at the specified position. Taking each reference mark 3 b sequentially, the position of each reference marks 3 b is recognized. Then, by the same manner as above, the position calibration data of the second moving table 4 B is obtained.

Herein, the reference position incorporation in the initial state conducted simultaneously with the calibration is described. In FIG. 2 ( a ), at the fixed position on the base 1 , the reference position recognition mark 9 M as the reference position is set. That is, four reference position recognition marks 9 M are disposed at specified positions on the base 1 . These reference position recognition marks 9 M have the function of calibrating the time-course changes of the position deviation state due to thermal distortion by temperature changes after start of operation of the mounting apparatus.

These reference position recognition marks 9 M are recognized by the camera of the moving table at the time of calibration of each moving table, and the result of recognition is stored as the reference position. After start of operation, by a specified interval, the position of these reference position recognition marks 9 M is recognized again. The obtained result of position recognition is compared with the stored reference position. As a result, the change of the position deviation state due to time-course changes after operation is detected. That is, the intersection angles 1 , 2 shown in FIG. 2 ( a ), and the displacement state due to thermal distortion of the mechanical parts can be detected. By adding this detection result to the position calibration data by calibration, the change of position deviation state due to time-course change can be corrected on every occasion.

The mounting process of a plurality of electronic components is described below by referring to the flowchart in FIG. 3 .

(1) Step ST 1 : First, the substrate 3 is delivered from the preceding step, and is positioned at the electronic component mounting position on the conveying path 2 .

(2) Step ST 2 : Next, the first moving table 4 A is driven, and the first camera 8 A is positioned on the recognition marks 3 a of the substrate 3 . The first camera 8 A recognizes the position of recognition marks 3 a sequentially. As a result, the position of the substrate 3 is recognized.

(3) Step ST 3 : In succession, the first moving table 4 A is driven, and the first mounting head 7 A is moved to the feeder (not shown). At the feeder, the first mounting head 7 A picks up an electronic component. Then the mounting head 7 A is moved onto the substrate 3 , and the electronic component is mounted on the substrate 3 . In this mounting operation, the first moving table 4 A is driven on the basis of the position recognition result of the substrate 3 at step ST 2 and the position calibration data intrinsic to the first moving table 4 A determined in the calibration.

(4) Step ST 4 : Later, by the second mounting head 4 B, an electronic component is mounted on the substrate 3 . At this time, the position of the substrate 3 is not recognized. By using the position recognition result determined by taking by the first camera 8 A at step ST 2 and the position calibration data intrinsic to the second moving table 4 B, similarly, driving of the second moving table 4 B is corrected. Thus, the substrate position recognition of each moving table required in the prior art for mounting electronic components by using a plurality of moving tables can be omitted, and, as a result, the total mounting time can be shortened.

(5) Step ST 5 : Then, by the first mounting head 7 A and second mounting head 7 B, a specified number of electronic components are mounted on the substrate 3 . The plurality of electronic components are mounted on a same substrate simultaneously by parallel operation.

(6) Thus, the mounting process of plurality of electronic components is completed.

In this way, when mounting a plurality of electronic components by a plurality of moving tables, the position deviation in mounting is corrected on the basis of the position recognition result determined by taking by only one camera of the plurality of cameras. As a result, the mounting time is shortened, and the productivity is enhanced.

According to the invention, in the substrate recognition by the camera conducted prior to mounting of electronic components on the substrate by means of a plurality of mounting heads, the substrate is recognized by only one camera of the plurality of cameras, and the plurality of mounting heads are positioned on the basis of this recognition result. Therefore, the substrate recognition time is shortened, the cycle time is shortened, and the productivity is enhanced.