JPH0537197A - Mounting method for electronic component - Google Patents

Abstract

PURPOSE:To efficiently and accurately screen print solder paste for mounting an electronic component such as various chip component, a surface mounting IC, etc., on a board on the board, and to accurately mount the component on the board. CONSTITUTION:An aiming point of an aligning mark 2 is brought into coincidence with a reference point of an aligning hole to a board 1 formed with a connecting conductor pattern and the mark 2 by using a printing screen formed with an aligning hole which can transparently observe the mark 2, the screen is superposed, and solder paste is screen printed. Thereafter, the position of the paste 30 corresponding to the aligning hole, printed to be superposed on the mark is detected, the position of a mounting head for holding the board 1 or an electronic component, and is corrected to mount the component at a designated position on the board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component mounting method capable of mounting various chip components and electronic components such as surface mounting ICs on a substrate with high accuracy.

[0002]

2. Description of the Related Art Conventionally, when an electronic component is mounted with high accuracy on a printed circuit board on which a connecting conductor pattern and a positioning mark (fiducial mark) are formed, as shown in FIG. An XY-θ table (a table that can be moved not only in the X and Y directions but also in the rotation direction in the horizontal plane) on which the printed circuit board 1 is mounted by copying the mark 2 with a television camera 3 as an image pickup device, or electronic parts The X and Y coordinates and the rotation angle θ of the mounting head holding the are corrected to mount the electronic component at the specified position on the substrate.

[0003]

By the way, in the case of the method of detecting the alignment mark formed on the printed circuit board from the beginning with the image pickup device as shown in FIG. 9, in the screen printing process executed before mounting the electronic parts. It is necessary to devise so that the solder paste does not adhere to the alignment mark. For example, Japanese Patent Application No. 2-28 proposed by the applicant
As shown in 1996, the substrate side alignment mark (fiducial mark) is seen through from the through hole formed on the printing screen side, and the position of both is adjusted by using the alignment mark and the outline of the through hole. The alignment is performed, but at this time, a transparent member is arranged in the through hole to prevent the solder paste from adhering to the substrate side alignment mark during screen printing. However, in this case, there is a problem in the durability of the transparent member, and there is also a problem that the transparency of the transparent member deteriorates during use.

On the other hand, the substrate side alignment mark and the screen side alignment mark are separately imaged by an image pickup device before the printing screen is placed on the substrate, and the positional relationship between the two is detected by the image processing device. It may be possible to perform screen printing by correcting the positional relationship between the screen and the screen, but in this case, if there is an error in the means for moving the screen or the board so as to overlap, there is a problem that the print displacement occurs in the solder paste. ..

In view of the above points, the present invention is capable of surely aligning both the substrate side alignment mark and the printing screen side alignment hole when screen printing. In addition, when mounting the electronic component, the solder paste mark printed on the substrate side alignment mark is imaged by the image pickup device to correct the position of the mounting head holding the substrate or the electronic component.
An object of the present invention is to provide an electronic component mounting method capable of mounting electronic components at specified positions on a substrate with high accuracy.

[0006]

In order to achieve the above object, in the electronic component mounting method of the present invention, the alignment mark can be seen through the substrate on which the connection conductor pattern and the alignment mark are formed. Using a printing screen with alignment holes formed, after aligning the aiming point of the alignment mark with the reference point of the alignment hole and screen printing the solder paste by overlapping the printing screen, the position The position of the solder paste mark corresponding to the alignment hole printed on the alignment mark is detected to correct the position of the board or the electronic component to be mounted on the board, and the electronic position is specified on the board. It is characterized by mounting parts.

[0007]

In the electronic component mounting method of the present invention, the substrate and the printing screen are positioned in a state in which the substrate having the connection conductor pattern and the alignment mark and the printing screen having the alignment hole are superposed on each other. In addition, solder paste screen printing can be performed. Therefore, there is no need to provide a transparent member or the like in the alignment hole to prevent the solder paste from adhering to the alignment mark on the substrate, and avoid problems such as durability of the transparent member and deterioration of transparency. You can In addition, there is no need to adopt a method of separately imaging and aligning the board-side alignment mark and the alignment mark of the printing screen, and the alignment between the substrate and the printing screen is easy and highly accurate. Screen printing of paste is possible. In addition, as a result of screen printing, the position of the solder paste mark printed on the alignment mark on the board is detected to correct the position of the mounting head that holds the board holding mechanism and electronic components, Electronic components can be accurately mounted at designated positions. As a result, it is possible to prevent a soldering failure and a standing phenomenon of a small chip component or the like due to a displacement of a printing pattern of a solder paste or a displacement of a mounting position of an electronic component. Therefore, it is possible to accurately and efficiently mount the fine-pitch surface mounting IC or the micro chip component.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an electronic component mounting method according to the present invention will be described below with reference to the drawings.

FIG. 1 is a front sectional view showing a process of picking up an image of a position of a solder paste mark printed on an alignment mark of a substrate by a television camera as an image pickup device.
5 to 5 illustrate the solder paste screen printing process.

First, the screen printing process will be described with reference to FIGS. In these figures, on the printed circuit board 1, connection conductor patterns (not shown) corresponding to electrodes, leads and various wirings of electronic parts to be mounted and circular alignment marks (fiducial marks) 2 are formed. This printed circuit board 1 is an X-Y of a screen printing machine.
Positioned and placed on the θ table 10. on the other hand,
The printing screen 11 fixed to the screen frame 15 of the screen printing machine as shown in FIG. 4 is a sheet of stainless steel or the like, and together with the printing pattern (the pattern for screen printing formed by the punched holes), the substrate side alignment mark. It has a circular alignment hole 12 corresponding to 2. Here, the positional relationship between the connection conductor pattern and the alignment mark 2 on the printed circuit board 1 is accurately defined, and the positional relationship between the print pattern on the screen 11 and the alignment hole 12 is also accurately defined. Note that FIG.
, The screen side alignment holes 12 are located at two corners of the screen 11, and the board side alignment marks 2 are also located at the two corners of the substrate 1 correspondingly. Aim point of circular alignment mark 2 of
(Center of circle) and reference points of two circular alignment holes 12
It is assumed that the mutual intervals of (circular centers) are set to be equal. As described above, the marks 2 and the holes 12 are provided at two positions respectively so that the shift in the rotational direction between the substrate 1 and the screen 11 can be detected and corrected.

A television camera 25 as an image pickup device included in the image processing apparatus 20 shown in FIG. 6 is arranged above the printing screen 11, and the circular alignment hole 12 of the screen 11 and the circular alignment mark on the substrate side are arranged. 2 A ring illuminator 26 is provided to illuminate the surrounding area. The irradiation range W of the ring illuminator 26 is set to be a region sufficiently larger than the screen side alignment hole 12. As shown in FIG. 6, the image processing device 20 includes a television camera 25 as an imaging device that captures an image in the field of view including the screen alignment hole 12 and the board-side alignment mark 2.
An image signal processing unit 21 for processing an image signal (luminance signal representing light and dark) from the television camera 25, an image memory 22 for storing processed image information, and an image information in the image memory 22 provided at two locations. Correction of the X-coordinate and Y-coordinate positions of the XY-θ table 10 on which the substrate 1 is positioned and mounted by recognizing the deviation between the reference point of the circular alignment hole 12 and the aiming point of the circular alignment mark 2 The calculation control unit 23 calculates the correction amounts Δθ for the amounts ΔX and ΔY and the rotation direction and corrects and drives the XY-θ table 10.

Using the above configuration, first, the step # 1 of aligning the printing screen and the substrate in the screen printing machine of FIG. 8 is executed. That is, the printing screen 11 fixed to the screen frame is superposed on the printed board 1 mounted and fixed on the XY-θ table 10, and the board-side circular alignment mark 2 is inserted through the screen-side circular alignment hole 12. It is set to be optically transparent. Then, the circular alignment hole 12 and the circular alignment mark 2
Both are captured by the TV camera 25 to capture an image. As shown in FIG. 3, the image viewed from above the screen side alignment hole 12 with the television camera 25 has a circular alignment mark 2 such as a copper foil as a bright portion a, a substrate surface as a dark portion b, and the outside thereof is a screen 11 made of stainless steel or the like. It becomes the light part c. Therefore, the television camera 25 can capture the circular contour of the circular alignment mark 2 and the circular contour of the circular alignment hole 12, and the reference point (center point) of the circular alignment hole 12 and the aiming point of the circular alignment mark 2 can be taken. The deviation from the point (center point) can be recognized on the image processing device 20 side, and the XY based on the recognition result can be obtained.
−X using the correction amounts ΔX, ΔY, and Δθ of the θ table 10 −
Operate the Y-θ table 10 to make a circular alignment hole 12
And the aiming point of the circular alignment mark 2 are matched.

Then, the solder paste screen printing step # 2 of FIG. 8 is executed in a state where the reference point of the circular alignment 12 and the aiming point of the circular alignment mark 2 are aligned. That is, as shown in FIG. 5, the squeegee 28 is moved in the direction of arrow K to spread the solder paste 27 thinly on the screen, and the screen printing operation is performed. After the screen printing step # 2 is performed, as shown in FIG. 1, the circular solder paste mark 30 formed for screen printing is concentrically formed so as to overlap the circular alignment mark 2 of the printed board 1. This solder paste mark 30 is the screen 1
The alignment hole 12 has a contour that matches the circular shape of the alignment hole 12 and has the same height as the thickness of the screen 11.

As shown in FIG. 7, the electronic component mounting machine comprises a mounting head 41 having a suction nozzle 42 for sucking and holding an electronic component 40 to be mounted on the printed circuit board 1, and the television camera 25A and the ring shown in FIG. Illuminator 26A
Have Then, prior to the mounting of the electronic component 40, an image capturing step # of the solder paste mark in FIG.
Execute 3. That is, as shown in FIG. 1, the solder paste mark 30 is used as a television camera 25 as an imaging device.
The image is captured at A and the image is captured. At that time, the ring illuminator 26A illuminates the substrate surface around the mark 30. Then, the position correcting step # 4 of the mounting head or the substrate supporting mechanism is performed. That is, also in this case, using the same image processing apparatus as in FIG. 6, the X coordinate of the mechanism such as the mounting head 41 holding the electronic component 40 to be mounted shown in FIG. The correction amounts ΔX and ΔY of the Y coordinate position and the correction amount Δθ for the rotation direction θ are calculated. As a result, when the substrate is fixedly positioned by a mechanism such as a table, the X and Y coordinate positions of the mounting head 41 are corrected by ΔX and ΔY, and the suction nozzle 42 is rotated by correction by Δθ. After that, the electronic component mounting step # 5 of FIG. 8 is executed. That is, when the mounting head 41 is moved downward with respect to the connection conductor pattern 50 and the solder paste pattern 51 formed on the board, the electronic component 4 is moved to a correct designated position on the printed board as shown by a virtual line in FIG.
Wear 0.

In the above embodiment, the relationship between the circular solder paste mark 30 and the solder paste pattern 51 applied on the printed circuit board is precisely defined, and the circular solder paste mark 30 and the printed circuit board 1 are formed from the beginning. Since the circular alignment mark (fiducial mark) 2 that has been formed has a concentric relationship, the relationship between the solder paste mark 30 and the connection conductor pattern 50 on the substrate is also accurately defined, so that the electronic component 40 is connected. The conductor pattern 50 and the solder paste application pattern 51 can be accurately mounted. As a result, when soldering is performed by the solder reflow, it is possible to prevent the displacement of the mounted component and the rising of the mounted component due to the melting of the solder. Therefore, it is possible to effectively cope with the mounting of fine-pitch components having a narrow lead interval and very small chip components.

In the case of the structure in which the printed board 1 is positioned and placed on the XY table, the XY table is moved by ΔX, ΔY in the position correction step # 4 of FIG.
The coordinate position may be corrected and the suction nozzle 42 may be corrected and rotated by Δθ.

Further, in the case of the structure in which the printed circuit board 1 is positioned and mounted on the XY-θ table, the XY-θ table is moved by Δθ for correction rotation, and
Correct the X and Y coordinate positions by ΔX and ΔY. At that time, Δθ
The amount of deviation in the X and Y directions due to the correction rotation of is also corrected.

Although the substrate-side alignment mark 2 and the screen-side alignment hole 12 have circular shapes in the above-mentioned embodiments, square, regular polygonal, triangular or other shapes may be adopted. ..

Further, the timing of cleaning the screen 11 can be recognized by detecting the deformation of the screen side alignment hole 12 (reduction of the area due to the attachment of the solder paste).

[0020]

As described above, according to the electronic component mounting method of the present invention, both the substrate side alignment mark and the printing screen side alignment hole are overlapped during screen printing. It is possible to surely align the positions, and it is possible to apply the solder paste accurately to the substrate surface. Moreover, when mounting the electronic component, the solder paste mark printed on the board side alignment mark is imaged by the image pickup device to correct the position of the mounting head holding the substrate or the electronic component with high accuracy. Electronic parts can be mounted at specified positions on the board. Also, because the solder paste mark is imaged, it is not necessary to place a transparent member in the alignment hole on the screen side to prevent the solder paste from adhering to the alignment mark on the board surface from the beginning. The screen structure is also simple.

[Brief description of drawings]

FIG. 1 is a front view with a part in section when a television camera images a solder paste mark after screen printing in an embodiment of an electronic component mounting method according to the present invention.

FIG. 2 is a partial cross-sectional front view showing a step of aligning a substrate and a printing screen in screen printing.

FIG. 3 is a plan view showing a positional relationship between a substrate side alignment mark and a screen side alignment hole.

FIG. 4 is a plan view showing an arrangement example of alignment holes formed in a printing screen.

FIG. 5 is a cross-sectional view showing a screen printing process of a solder paste after the substrate and the screen are aligned.

FIG. 6 is a block diagram showing an example of an image processing apparatus.

FIG. 7 is a front view showing an electronic component mounting process in the electronic component mounting machine.

FIG. 8 is a flowchart showing the operation of the embodiment.

FIG. 9 is a sectional view illustrating a conventional method of mounting electronic components.

[Explanation of symbols]

 1 Printed Circuit Board 2 Alignment Mark 3,25,25A TV Camera 10 XY-θ Table 11 Printing Screen 12 Alignment Hole 20 Image Processing Device 30 Solder Paste Mark 40 Electronic Component 41 Mounting Head 42 Adsorption Nozzle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 13/08 B 8315-4E

Claims (1)

Claim: What is claimed is: 1. A printing screen comprising: a substrate on which a connection conductor pattern and alignment marks are formed, and alignment holes through which the alignment marks can be seen.
After aligning the aiming point of the alignment mark with the reference point of the alignment hole and performing screen printing of the solder paste by overlapping the printing screen, the alignment printed on the alignment mark. Electronic component mounting characterized in that the position of the solder paste mark corresponding to the hole is detected, the position of the substrate or the electronic component to be mounted on the substrate is corrected, and the electronic component is mounted at a specified position on the substrate. Method.