JP2001315298A - Screen printing apparatus and screen printing process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screen printing apparatus and a screen printing process by which printing conditions can be easily set without deviation and quality of printing can be ensured. SOLUTION: In a screen printing process in which a screen mask is brought into contact with a base sheet to print a cream solder on the base sheet, based on results on measurement obtained by measuring the top face of the screen mask at a printing position and the top face of the base sheet at a base sheet measuring position by means of a laser measuring device 20 on the base sheet and the screen mask after printing, the screen printing conditions are set by using set data in a printing condition library stored in a data storing part 32 by means of a printing condition setting part 35 and the set printing conditions are stored in the data storing part 32. It is possible thereby that setting works can be easily performed and deviation in setting of printing conditions can be excluded and quality of printing can be stably ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing apparatus and a screen printing method for printing paste such as cream solder or conductive paste on a substrate.

[0002]

2. Description of the Related Art In an electronic component mounting process, screen printing is used as a method for printing paste such as cream solder on a substrate. In this method, a screen mask provided with a pattern hole according to a printing target portion is brought into contact with a substrate, cream solder is supplied on the screen mask, and a squeegee is slid, so that the squeegee slides on the substrate through the pattern hole. Is to print cream solder.

In order to secure good print quality in this screen printing, it is necessary to appropriately set various printing conditions in accordance with a printing target. For example, the squeegee speed at which the squeegee slides on the screen mask during screen printing, the printing pressure value at which the squeegee is pressed against the screen mask, and the relative speed of the substrate to the screen mask when the substrate is separated from the screen mask after printing Must be set in accordance with the characteristics of the printing target, such as a plate separation speed indicating the printing. The printing condition setting operation has been conventionally performed by a skilled worker mainly based on experience and personal skills.

[0004]

However, it has been difficult in recent years to secure skilled workers, and the production mode has shifted to multi-product small-lot production. Under the current situation, the situation has to be reached in which unskilled persons have to perform the above-mentioned condition setting work. For this reason, the setting of the printing conditions tends to vary due to the skill difference of the worker,
In conventional screen printing, there is a problem that it is difficult to stably secure print quality due to variations in printing conditions.

Accordingly, an object of the present invention is to provide a screen printing apparatus and a screen printing method capable of easily setting print conditions without variation and ensuring print quality.

[0006]

According to a first aspect of the present invention, there is provided a screen printing apparatus in which a screen mask provided with a pattern hole is brought into contact with a substrate, and a squeegee head is slid on the screen mask to thereby form the pattern. A screen printing apparatus that prints a paste on a substrate through a hole, a substrate positioning unit that positions the substrate relative to a screen mask, and a screen mask at a printing position and a substrate at a substrate measurement position from an upper surface side. Three-dimensional measuring means for three-dimensionally measuring, moving means for moving the three-dimensional measuring means, printing condition setting means for setting screen printing conditions based on the measurement results of the three-dimensional measuring means, and the set printing Printing condition storage means for storing conditions.

According to a second aspect of the present invention, there is provided a screen printing method, wherein a screen mask provided with a pattern hole is brought into contact with a substrate, and a squeegee head is slid on the screen mask, so that the squeegee head slides on the substrate through the pattern hole. A screen printing method for printing a paste, comprising: a post-print measurement step of measuring a screen mask at a printing position and / or a substrate at a substrate measurement position from a top surface side by a three-dimensional measurement unit, for a printed substrate and a screen mask; The method includes a printing condition setting step of setting screen printing conditions based on a measurement result of the measuring means, and a step of storing the set printing conditions in the printing condition storage means.

According to a third aspect of the present invention, there is provided the screen printing method according to the second aspect, wherein the post-printing measurement step is performed after a test print before the start of actual printing, and the setting result in the printing condition setting step. To set printing conditions for actual printing.

According to a fourth aspect of the present invention, there is provided a screen printing method according to the second aspect, wherein the measuring step after printing is performed at a predetermined timing during actual printing work.
The printing conditions for actual printing are changed according to the setting result in the printing condition setting step.

A screen printing method according to a fifth aspect of the present invention is the screen printing method according to any one of the second to fourth aspects, wherein the printing conditions include a squeegee speed at which the squeegee is slid, and a squeegee used as a screen mask. It includes a printing pressure value pressed against the printing plate, a plate separation speed indicating a relative speed of the substrate with respect to the screen mask when the substrate is separated from the screen mask, and a plate separation distance indicating a relative moving distance.

According to the present invention, the printed substrate and the screen mask are measured from the upper surface side by the three-dimensional measuring means, and the screen printing conditions are set based on the measurement results, thereby eliminating variations in the printing condition settings. As a result, printing quality can be stably ensured.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a front view of a screen printing apparatus according to one embodiment of the present invention, FIG. 2 is a side view of the screen printing apparatus according to one embodiment of the present invention, and FIG. 3 is a screen printing apparatus according to one embodiment of the present invention. FIG. 4 is a perspective view of a laser measuring device of the screen printing apparatus according to one embodiment of the present invention, FIG. 5 is a block diagram showing a configuration of a control system of the screen printing apparatus of one embodiment of the present invention, FIG. 6 is a diagram showing data of a screen printing condition library according to one embodiment of the present invention, and FIG. 7 is a plan view of a substrate to be screen printed according to one embodiment of the present invention.

First, the structure of the screen printing device will be described with reference to FIGS. 1 and 2, a substrate positioning unit 1 serving as a substrate positioning unit stacks a θ-axis table 4 on a moving table including an X-axis table 2 and a Y-axis table 3, and further has a Z-axis table 5 thereon. A substrate holding unit 7 is provided on the Z-axis table 5 for holding the substrate 6 sandwiched by the clampers 8 from below. The substrate 6 to be printed is carried into the substrate positioning unit 1 by the carry-in conveyor 14 shown in FIGS. By driving the substrate positioning unit 1, the position of the substrate 6 can be adjusted. The printed substrate 6 is carried out by the carry-out conveyor 15.

A screen mask 10 is provided above the substrate positioning unit 1. The screen mask 10 is configured by mounting a mask plate 12 on a holder 11. The substrate 6 is positioned with respect to the mask plate 12 by the substrate positioning unit 1 and abuts from below. A squeegee head 13 is disposed on the screen mask 10 so as to be able to reciprocate in a horizontal direction. With the substrate 6 in contact with the lower surface of the mask plate 12, the mask plate 12
An electrode 6a formed on the surface of the substrate 6 (see FIG. 3) is supplied by supplying cream solder 9, which is a paste, onto the surface of the substrate 6 by sliding the squeegee 13a of the squeegee head 13 into contact with the surface of the mask plate 12. The cream solder 9 is printed on the upper surface through a pattern hole 12a (see FIG. 3) provided in the mask plate 12.

Above the screen mask 10, a laser measuring device 20 as a three-dimensional measuring means is provided.
As shown in FIG. 3, the laser measuring device 20 is horizontally moved in the X and Y directions by an X-axis table 21 and a Y-axis table 22, and can be moved up and down by elevating means 23 (FIGS. 1 and 2). By driving the lifting / lowering means 23, the laser measurement device 20 is lowered to the measurement height position. X-axis table 21, Y-axis table 22, and elevating means 23
Are moving means for moving the laser measuring device 20.

The laser measuring device 20 has a function of measuring displacement in the vertical direction by irradiating a laser beam and a scanning mechanism for scanning the laser irradiation position in the XY directions.
By scanning the irradiation point P within the measurement range R as shown in FIG. 4, the vertical position of the surface of the measurement object within the measurement range R is continuously detected, and the three-dimensional shape of the measurement object can be detected. It has become.

By moving the laser measuring device 20 with respect to the substrate 6 and the mask plate 12 by the moving means, a three-dimensional shape measurement can be performed from an upper surface side of an arbitrary range of the substrate 6 and the mask plate 12. it can. And by processing the obtained detection data,
It is possible to detect the arrangement pattern of the electrodes 6a, which are the characteristic portions of the substrate 6, and the arrangement pattern of the pattern holes 12a, which are the characteristic portions of the screen mask 10, and perform three-dimensional measurement using the substrate 6 after screen printing as a measurement target. Thus, the shape of the cream solder 9 printed on the substrate 6 can be detected three-dimensionally.

Next, the configuration of the control system of the screen printing apparatus will be described with reference to FIG. In FIG.
U30 is an overall control unit that performs overall control of each unit described below. The program storage unit 31 includes an operation program for screen printing, a processing program for detecting the shape of the substrate 6 and the mask plate 12 from a detection signal of the laser measurement device 20, a program for determination processing in print inspection, and a program for print condition setting processing. Various programs such as programs are stored. The data storage unit 32 stores print condition data set for each type, together with reference value data for determination processing in print inspection and a print condition library in which data necessary for setting print conditions are compiled. That is, the data storage unit 32 is a printing condition storage unit.

The mechanism control unit 33 includes the substrate positioning unit 1, the carry-in conveyor 14, the carry-out conveyor 15, and the X-axis table 2.
1. The operation of each mechanism such as the Y-axis table 22 is controlled. The shape detection unit 34 processes the detection signal obtained by scanning the laser measurement device 20 to form an electrode arrangement pattern indicating the planar arrangement of the electrodes 6 a provided on the substrate 6 and a pattern provided on the mask plate 12. Hole 12a
And the shape of the cream solder 9 on the substrate 6 after printing is detected.

Print condition setting unit 35 (print condition setting means)
Sets the screen printing conditions. That is, the squeegee speed at which the squeegee 13a slides on the mask plate 12 during screen printing, the printing pressure value at which the squeegee 13a is pressed against the mask plate 12, and the substrate 6 when the substrate is separated from the mask plate 12 after printing. Various parameters such as a plate separation speed indicating a relative speed with respect to the mask plate 12 are set according to the characteristics of the printing target.

The substrate / mask judging section 36 includes the shape detecting section 3
By comparing the electrode arrangement pattern of the substrate 6 detected by the step 4 and the opening pattern of the screen mask 10 with a reference pattern on the design data, the quality of the substrate 6 and the mask plate 12 supplied to the screen printing apparatus is determined. . The print determination unit 37 determines the quality of the printing state by comparing the shape data of the cream solder 9 obtained by measuring the screen printed substrate 6 with the laser measuring device 20 with reference data stored in advance. .

Next, setting of printing conditions will be described.
FIG. 6 shows the data contents of the printing condition library. The printing condition library includes the above parameters (sliding the squeegee) for each combination of the typical dimensions of the electrodes of the substrate (eg, electrode width dimensions) and the typical dimensions of the screen mask provided with pattern holes (eg, mask plate thickness). Squeegee speed, printing pressure value for pressing the squeegee against the screen mask, plate separation speed indicating the relative speed of the substrate to the screen mask when the substrate is separated from the screen mask, and plate separation distance indicating the relative movement distance). Is a combination of the two. The numerical values of these parameters also differ depending on the physical properties of the cream solder 9 to be printed.

That is, the type of cream solder 9 to be printed, the substrate 6 to be printed, and the screen mask 1 to be used
When 0 is specified by the electrode representative dimension and the mask representative dimension, a combination of the above parameters is selected,
Thereby, each parameter is automatically set.

Normally, a single combination of printing condition parameters is set on the same substrate as the printing condition. However, in a special case, different printing conditions are used for a specific printing range by using a combination of a plurality of parameters. May be applied. That is, as shown in FIG. 7, a narrow pitch electrode 6b and a normal electrode 6c are provided in the same substrate 6.
Are mixed in the narrow pitch electrode 6
If the squeegee moving speed and the printing pressure value are set to be different from those of the other normal range C only when the squeegee 13a passes through the narrow pitch range B provided with the b, the squeegees respectively appropriate for the electrodes having different printing characteristics. Printing can be performed at the speed and printing pressure value.

This screen printing apparatus is configured as described above, and a method for setting screen printing conditions will be described below. First, the type is switched to a new type to be printed, and the screen mask 1 is changed in accordance with the type.
When 0 is attached, a screen mask inspection is performed.
This inspection is performed by performing three-dimensional measurement of the screen mask 10 from the upper surface side while moving the laser measuring device 20 on the screen mask 10 by the X-axis table 21 and the Y-axis table 22 with the screen mask 10 mounted. Done. By this inspection, the thickness dimension of the mounted screen mask 10 is detected and pass / fail is determined.

Next, the inspection of the substrate 6 is performed. When the substrate 6 to be printed is carried from the carry-in conveyor 14 onto the substrate positioning unit 1, the substrate positioning unit 1 is moved from below the screen mask 10 in the Y direction to the substrate measurement position (see FIG. 2). (See the substrate positioning unit 1 and the substrate 6 indicated by broken lines.) Then, the substrate 6 is similarly three-dimensionally measured from the upper surface side by the laser measuring device 20. This allows
The width and length of the electrode to be printed on the substrate 6 are determined.

Next, if the representative dimensions of the electrodes of the substrate 6 and the thickness of the mask plate 12 are obtained, the type of the cream solder 9 and the data of the substrate 6 and the screen mask 10 obtained by the measurement are input in advance. Based on this, the parameters of the printing conditions in the printing condition library are read. Then, test printing before the start of actual printing is performed using the parameters of the printing conditions.

First, the cream solder 9 is supplied onto the screen mask 10, and the squeegee 13 a is reciprocated to perform preliminary squeezing for kneading the cream solder 9. Is brought into contact with the lower surface of the mask plate 12. Next, the squeegee head 13 is moved to remove the cream solder 9 from the pattern holes 12.
The printing is performed on the electrode 6a of the substrate 6 through a. After this, Z
By lowering the axis table 5 and separating the plate, cream solder 9 is printed on the electrodes 6 a of the substrate 6.

Thereafter, a printing inspection of the substrate 6 after the test printing is performed (post-printing measurement step). This inspection is performed by moving the substrate positioning unit 1 again from below the screen mask 10 to the substrate measurement position, and three-dimensionally measuring the printed substrate 6 from the upper surface side by the laser measurement device 20.
If it is determined by this inspection that the printing condition is good, the parameters of the printing conditions that were initially read are determined to be appropriate, and these parameters are used as printing conditions for actual printing on the board. It is set (print condition setting step) and stored in the data storage unit 32.

In the post-printing measurement, the screen mask 10 may be three-dimensionally measured by the laser measuring device 20. This measurement makes it possible to obtain data for specifying the cause of the printing failure, and to improve the amount of information and accuracy at the time of feedback described below.

If a defect is detected in the post-printing measurement after the test printing, a process for feeding back the printing conditions is performed. This feedback is performed based on feedback data stored in the printing condition library in advance. That is, the inspection result is output as numerical data for each predetermined item such as a print area and a print height of each electrode, and a deviation from the reference value is obtained by comparing the output value with a reference value set as an appropriate value. .

Then, given this deviation,
The parameters of the printing condition having a correlation are corrected in one of the + and-directions by a correction amount corresponding to the deviation. The data indicating the correlation between the deviation and the correction amount is created by changing the printing conditions in various ways and organizing the results of the trial printing for condition setting performed systematically using a statistical method or the like. Are stored in the print condition library of the data storage unit 32 in the same manner.

After the printing condition correction, a new trial printing is performed, and the trial result is similarly inspected. Then, after confirming that the printing result is good, the main printing operation is started. In this printing operation, feedback of printing conditions is performed at a preset interval. That is, the post-printing inspection is performed on the substrate 6 during production by sampling with the laser measuring device 20 (post-printing measurement step).

Then, the same inspection data is obtained, the deviation from the reference value is obtained for each inspection item, and necessary parameters are corrected to change the printing conditions for actual printing. Thereby, even when the viscosity of the cream solder 9 changes due to the fluctuation of the environmental temperature, it is possible to always maintain the printing conditions in an appropriate range and to secure a good printing quality.

As described above, in the screen printing shown in the present embodiment, the printed substrate 6 and the screen mask 10 are measured from the upper surface side by the three-dimensional measuring means, and the screen printing conditions are set based on the measurement results. It is like that. As a result, it is possible to easily perform the printing condition setting operation which conventionally required a complicated condition setting operation by a skilled operator, and it is possible to eliminate the variation in the printing condition setting and to secure the stable printing quality. .

In the above embodiment, an example of an open type squeegee head having a plate-shaped squeegee 13a is shown as a type of squeegee head, but the present invention is not limited to this.
A closed type squeegee head may be used in which cream solder is stored inside, and the cream solder is slid on a mask plate while pressurizing the cream solder to fill the pattern holes with cream solder.

[0037]

According to the present invention, the printed substrate and the screen mask are measured from the upper surface side by three-dimensional measuring means, and the screen printing conditions are set based on the measurement results. The work can be easily performed, and the variation in the printing condition setting can be eliminated to ensure the stable printing quality.

[Brief description of the drawings]

FIG. 1 is a front view of a screen printing apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of the screen printing apparatus according to the embodiment of the present invention.

FIG. 3 is a plan view of a screen printing apparatus according to an embodiment of the present invention.

FIG. 4 is a perspective view of a laser measuring device of the screen printing device according to the embodiment of the present invention.

FIG. 5 is a block diagram illustrating a configuration of a control system of the screen printing apparatus according to the embodiment of the present invention.

FIG. 6 is a diagram showing data of a screen printing condition library according to the embodiment of the present invention;

FIG. 7 is a plan view of a substrate to be screen printed according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate positioning part 6 Substrate 9 Cream solder 10 Screen mask 12 Mask plate 12a Pattern hole 13 Squeegee head 20 Laser measuring device 32 Data storage part 34 Shape detection part 35 Printing condition setting part 37 Printing judgment part

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Shigetaka Abe 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (for reference) 2C035 AA06 FA31 FB23 FC07 FD01 FD15 FD19 5E319 AC01 BB05 CD04 CD29 CD53 GG03 GG15 5E343 AA02 AA11 BB72 DD04 DD20 FF02 FF04 FF13 FF30 GG11 GG18

Claims (5)

[Claims] 1. A screen printing apparatus for printing a paste on a substrate through a pattern hole by bringing a screen mask provided with pattern holes into contact with a substrate and sliding a squeegee head on the screen mask. Substrate positioning means for positioning the substrate relative to the screen mask; three-dimensional measuring means for three-dimensionally measuring the screen mask at the printing position and the substrate at the substrate measurement position from the upper surface side; Moving means for moving the dimension measuring means, printing condition setting means for setting screen printing conditions based on the measurement result of the three-dimensional measuring means, and printing condition storing means for storing the set printing conditions. Characteristic screen printing device. 2. A screen printing method in which a screen mask provided with pattern holes is brought into contact with a substrate, and a squeegee head is slid on the screen mask to print a paste on the substrate through the pattern holes. The post-printing measuring step of measuring the screen mask at the printing position and / or the substrate at the substrate measuring position by the three-dimensional measuring means on the printed substrate and the screen mask based on the measurement results of the three-dimensional measuring means A screen printing method comprising: a printing condition setting step of setting screen printing conditions; and a step of storing the set printing conditions in a printing condition storage unit. 3. The printing condition for actual printing is set after the test printing before starting the actual printing, and the printing condition for the actual printing is set according to the setting result in the printing condition setting process. Screen printing method. 4. The printing condition for actual printing is changed at a predetermined timing during the actual printing operation, and the printing condition for actual printing is changed according to the result of the setting in the printing condition setting process. Screen printing method. 5. The printing conditions include a squeegee speed for sliding the squeegee, a printing pressure value for pressing the squeegee against the screen mask, and a relative speed of the substrate to the screen mask when the substrate is separated from the screen mask. 5. The screen printing method according to claim 2, further comprising a plate separation distance indicating a plate separation speed and a relative movement distance.