Method of screen printing

A screen printing apparatus includes a mask and a printing head. The mask has a first opening provided in a first region, and a second opening provided in a second region which is thicker than the first region. The printing head fills the first opening with a paste in a state where a substrate is in contact with the first region, and fills the second opening with the paste in a state where the substrate is in contact with the second region.

BACKGROUND

1. Field of the Invention

One or more embodiments of the present invention relate to a screen printing apparatus which prints a paste on a substrate by using a mask in which an opening is formed, and to a component mounting line which is provided with the screen printing apparatus.

2. Description of Related Art

A screen printing apparatus prints a paste on a substrate by filling an opening with the paste by a printing head after bringing a mask, in which an opening is formed, into contact with the substrate. The thickness of the paste printed on the substrate can be set according to the thickness of the mask, and the thickness of the paste on one substrate is generally a single thickness (one type). Regarding the substrate on which a small-sized component, such as a chip component, and a large-sized component, such as a connector, coexist, since a larger amount of paste is necessary when bonding the large-sized component than that of when bonding the small-sized component, there is also a case where two types of pastes which have different thicknesses are necessary to be printed on the substrate. In this case, in the related art, two masks which have different thicknesses from each other and in which openings are respectively formed are installed in parallel in the screen printing apparatus, and after performing the printing by the mask which is thinner than the other, the printing is performed by a mask which is thicker than the other (for example, refer to JP-A-2014-120745).

SUMMARY

However, when two masks are disposed in one screen printing apparatus, there is a problem that the size of the entire apparatus increases.

Here, an object of one or more embodiments of the present invention is to provide a screen printing apparatus which can print two types of pastes which have different thicknesses from each other without increasing the size of the apparatus, and a component mounting line.

According to an aspect of the present invention, there is provided a screen printing apparatus, including: a mask which has a first opening provided in a first region, and a second opening provided in a second region which is thicker than the first region; and a printing head which fills the first opening with a paste in a state where a substrate is in contact with the first region, and fills the second opening with the paste in a state where the substrate is in contact with the second region.

According to another aspect of the present invention, there is provided a component mounting line, including: the screen printing apparatus; and a component mounting apparatus which mounts a component onto a substrate on which the paste is printed by the screen printing apparatus.

According to one or more embodiments of the present invention, it is possible to print two types of pastes which have different thicknesses from each other without increasing the size of the apparatus.

DETAILED DESCRIPTION

First Embodiment

FIG. 1illustrates a component mounting line1according to a first embodiment of the present invention. The component mounting line1mounts a component3onto a substrate2and manufactures a mounted substrate2J, and is provided with a screen printing apparatus4and a component mounting apparatus5which is disposed on a downstream process side thereof. The screen printing apparatus4receives the substrate2which is input from an upstream process side, screen-prints a paste Pst on an electrode2D of the substrate2, and delivers the substrate2to the component mounting apparatus5. The component mounting apparatus5receives the substrate2from the screen printing apparatus4, and mounts the component3onto the electrode2D on which the paste Pst is printed. In the following description, for convenience, a horizontal direction of the component mounting line1when viewed from an operator OP is considered as an X-axis direction, and the substrate2flows from a left side to a right side in the X-axis direction. In addition, a longitudinal direction of the component mounting line1when viewed from the operator OP is considered as a Y-axis direction, and a vertical direction is considered as a Z-axis direction.

As illustrated inFIG. 2, the electrode2D of the substrate2includes two types of electrodes (a first type electrode2aand a second type electrode2b). The first type electrode2ais an electrode on which a small-sized component3, such as a chip component, is mounted, and the second type electrode2bis an electrode on which a large-sized component3, such as a connector, is mounted. For this reason, a larger amount of paste Pst is necessary on the second type electrode2bthan that which is necessary on the first type electrode2a, and, on the second type electrode2b, the screen printing apparatus4prints the paste Pst which is thicker than that which is printed on the first type electrode2a. A region S1illustrated inFIG. 2indicates a region on the substrate2provided with the first type electrode2a, and a region S2indicates a region on the substrate2provided with the second type electrode2b.

InFIGS. 3 and 4, the screen printing apparatus4is provided with a substrate holding and moving mechanism12on a base11, and a mask13is provided above the substrate holding and moving mechanism12. On an upstream process side of the substrate holding and moving mechanism12on the base11, a carrying-in conveyor14which receives the substrate2input from the outside of the screen printing apparatus4and carries the substrate2to the substrate holding and moving mechanism12is provided. On a downstream process side of the substrate holding and moving mechanism12on the base11, a carrying-out conveyor15which receives the substrate2from the substrate holding and moving mechanism12and carries the substrate2to an apparatus (here, the component mounting apparatus5) on the downstream process side is provided. A camera16is provided below the mask13, and a printing head17is provided above the mask13.

InFIG. 4, the substrate holding and moving mechanism12includes a substrate holding portion21and a moving table portion22. The substrate holding portion21is provided with a positioning conveyor31(refer toFIG. 3), a lower receiving portion32, and one pair of clampers33(refer toFIG. 3). The positioning conveyor31positions the substrate2which is sent from the carrying-in conveyor14, to a predetermined clamping position. The lower receiving portion32supports the substrate2which is positioned to the clamping position by the positioning conveyor31from below, and the pair of the clampers33clamps the substrate2from the Y-axis direction. In this manner, the substrate2is held by the lower receiving portion32and the pair of clampers33. Among the two clampers33provided in the substrate holding portion21, a clamp which is positioned on the operator OP side is called a front clamper33F, and a clamp which is positioned on a side opposite to the operator OP is called a rear clamper33R. The moving table portion22includes a table mechanism which is stacked in multiple layers, and moves the substrate holding portion21which holds the substrate2in a direction within a horizontal surface and in the vertical direction.

InFIG. 5, the mask13has a shape of a rectangular plate which widens on an XY surface. An outer circumference of the mask13is supported by a frame member13w. The thicknesses in a region on a front side and in a region on a rear side of the mask13are different from each other, and the thickness in the region on the rear side is thicker than the thickness in the region on the front side.

As illustrated inFIGS. 4 and 5, a front masking region R1(first region) which is a region that comes into contact with the substrate2is included in the region on the front side of the mask13, and a rear masking region R2(second region) which is a region that comes into contact with the substrate2is included in the region on the rear side of the mask13. A region between the front masking region R1and the rear masking region R2includes an intermediate region Rm which has a difference (step) in thickness between the front masking region R1and the rear masking region R2. In the first embodiment, a lower surface of the front masking region R1and a lower surface of the rear masking region R2are the same plane, and the height of the lower surface of the front masking region R1and the height of the lower surface of the rear masking region R2are equivalent to each other (FIG. 6).

A first type opening K1(first opening) is provided in the front masking region R1. A second type opening K2(second opening) is provided in the rear masking region R2. The first type opening K1is provided in a first pattern which corresponds to the disposition of the first type electrode2a, and the second type opening K2is provided in a second pattern which corresponds to the disposition of the second type electrode2b. In other words, the mask13has the first type opening K1in the front masking region R1, and has the second type opening K2in the rear masking region R2which is thicker than the front masking region R1.

InFIGS. 3 and 4, the camera16is provided with an upper imaging portion16ain which an imaging visual field faces upward, and a lower imaging portion16bin which an image visual field faces downward. The camera16is driven by a camera moving mechanism16K and moves on the XY surface. The upper imaging portion16aof the camera16images mask-side marks13m(FIG. 5) which are respectively provided in the front masking region R1and the rear masking region R2of the mask13, from below. The lower imaging portion16bof the camera16images substrate-side marks2m(FIG. 3) of the substrate2held by the substrate holding portion21, from above.

The substrate holding and moving mechanism12raises the substrate2and brings the substrate2into contact with a lower surface of the mask13after positioning the substrate2with respect to mask13referring to a relative position of the mask-side mark13mand the substrate-side mark2mwhich are imaged by the camera16. When printing the paste Pst on the first type electrode2a, the substrate2is brought into contact with the front masking region R1(FIG. 7A), and when printing the paste Pst on the second type electrode2b, the substrate2is brought into contact with the rear masking region R2(FIG. 7B).

When the substrate2which is held in the substrate holding portion21is brought into contact with the front masking region R1, the front clamper33F is positioned in front of the front masking region R1, and the rear clamper33R is positioned in the intermediate region Rm which is behind the front masking region R1(FIG. 7A). Meanwhile, when the substrate2which is held by the substrate holding portion21is brought into contact with the rear masking region R2, the rear clamper33R is positioned behind the rear masking region R2, and the front clamper33F is positioned in the intermediate region Rm which is in front of the rear masking region R2(FIG. 7B). The paste Pst is supplied to the intermediate region Rm when the printing is started (FIG. 5).

When the substrate2is brought into contact with the front masking region R1, the first type electrode2aof the substrate2matches the first type opening K1of the mask13, and is exposed on the upper surface side of the mask13through the first type opening K1(FIG. 8A). A thickness T1of the mask13in the front masking region R1is a thickness of the paste Pst when the paste Pst is printed on the first type electrode2aas it is. Meanwhile, when the substrate2is brought into contact with the rear masking region R2, the second type electrode2bmatches the second type opening K2of the mask13, and is exposed on the upper surface side of the mask13through the second type opening K2(FIG. 8B). A thickness T2of the mask13in the rear masking region R2is a thickness of the paste Pst when the paste Pst is printed on the second type electrode2bas it is.

InFIGS. 3 and 4, the printing head17includes a moving base41which extends in the X-axis direction, two squeegees42which are disposed to face each other in the Y-axis direction below the moving base41, and two squeegee raising and lowering cylinders43which raise and lower each squeegee42provided in the moving base41with respect to the moving base41. The moving base41is driven by a printing head moving mechanism17K and moves in the Y-axis direction, and accordingly, each squeegee42is moved in the Y-axis direction. Among the two squeegees42provided to be aligned in the Y-axis direction, a squeegee which is positioned on a front side (right side of a paper surface ofFIG. 4) is called a front squeegee42F, and a squeegee which is positioned on a rear side (left side of the paper surface ofFIG. 4) is called a rear squeegee42R.

The screen printin apparatus4includes a control device50(FIG. 9). The control device50may include, e.g., a memory configured to store instructions; and at least one processor configured to execute the instructions to cause the screen printing apparatus4to perform at least one of the operations thereof. A control of each of a carrying operation of the substrate2by the carrying-in conveyor14, holding and moving operations of the substrate2by the substrate holding and moving mechanism12, and a carrying operation of the substrate2by the carrying-out conveyor15is performed by the control device50which is provided in the screen printing apparatus4. In addition, a control of each of a moving operation of the camera16by the camera moving mechanism16K, a moving operation of the printing head17by the printing head moving mechanism17K, a raising and lowering operation of each squeegee42by the squeegee raising and lowering cylinder43, and an imaging operation of the camera16is also performed by the control device50. Image data obtained by the imaging of the camera16is sent to the control device50, and image recognition processing is performed in an image processing unit50a(FIG. 9) of the control device50.

Next, an operation of the screen printing apparatus4configured as described above will be described. The screen printing apparatus4prints (secondary printing) the paste Pst on the second type electrode2bby using the second type opening K2of the rear masking region R2after printing (primary printing) the paste Pst on the first type electrode2aby using the first type opening K1of the front masking region R1.

When the substrate2is input from the upstream process side, the carrying-in conveyor14receives the substrate2, and delivers the substrate2to the substrate holding portion21. The substrate holding portion21positions the substrate2received from the carrying-in conveyor14to the predetermined clamping position by the positioning conveyor31, supports the substrate2by the lower receiving portion32from below, and then, clamps the substrate2by the pair of clampers33(illustrated with an arrow A inFIG. 10A). In this manner, when the substrate holding portion21holds the substrate2, the substrate holding and moving mechanism12moves the substrate holding portion21, and positions the substrate2below the front masking region R1(illustrated with an arrow B1inFIG. 10B).

When the substrate2is positioned below the front masking region R1, the camera16moves, images the mask-side mark13min the front masking region R1by the upper imaging portion16a, and images the substrate-side mark2mby the lower imaging portion16b(FIG. 11A). When the imaging by the camera16is finished, the substrate holding and moving mechanism12moves and raises the substrate2so that the obtained mask-side mark13mand the substrate-side mark2mmatch each other when viewed in a plan view, and brings the substrate2into contact with the front masking region R1(illustrated with an arrow C1inFIG. 11B). Accordingly, each first type electrode2amatches the inside of the corresponding first type opening K1, and is exposed on the upper surface side of the mask13. Meanwhile, each second type electrode2bis in a state of being covered with the mask13(FIG. 12AtoFIG. 12B).

When the substrate2comes into contact with the front masking region R1, the printing head17lowers the rear squeegee42R, and a lower end thereof abuts against the intermediate region Rm of the mask13. In addition, by moving the rear squeegee42R from the intermediate region Rm to the region on the front side of the front masking region R1, the rear squeegee42R is slidably moved on the front masking region R1(illustrated with an arrow D1inFIGS. 13A and 14A). When the rear squeegee42R moves up to the front region of the front masking region R1, after the printing head17raises the rear squeegee42R, now, the front squeegee42F is lowered, and a lower end thereof abuts against the mask13. In addition, by moving the front squeegee42F from the region on the front side of the front masking region R1to the intermediate region Rm, the front squeegee42F is slidably moved on the front masking region R1(illustrated with an arrow D2inFIG. 13B). When the inside of each first type opening K1is filled with the paste Pst as the squeegee42slidably moves (FIG. 14A), the substrate holding and moving mechanism12lowers the substrate holding portion21(illustrated with an arrow C2inFIG. 15A), and snapping-off is performed. Accordingly, a layer of the paste Pst having a thickness which corresponds to the thickness T1of the mask13of the front masking region R1is formed on each first type electrode2aof the substrate2(FIG. 14B), and the primary printing is finished.

When the primary printing is finished, the substrate holding and moving mechanism12moves the substrate holding portion21, and positions the substrate2below the rear masking region R2(illustrated with an arrow B2inFIG. 15B). When the substrate2is positioned below the rear masking region R2, the camera16moves, images the mask-side mark13min the rear masking region R2by the lower imaging portion16a, and images the substrate-side mark2mby the lower imaging portion16b(FIG. 16A). When the imaging by the camera16is finished, the substrate holding and moving mechanism12moves and raises the substrate2so that the obtained mask-side mark13mand the substrate-side mark2mmatch each other when viewed in a plan view, and brings the substrate2into contact with the rear masking region R2(illustrated with an arrow C1inFIG. 16B). Accordingly, each second type electrode2bmatches the corresponding second type opening K2, and is exposed on the upper surface side of the mask13. Meanwhile, the paste Pst printed on the first type electrode2ais stored inside a hollow H for avoiding interference which is provided in the rear masking region R2(FIG. 17AtoFIG. 17B). In addition, after finishing the primary printing, the front squeegee42F is maintained in a state where the lower end thereof abuts against the intermediate region Rm and is stopped.

The above-described hollow H is provided in a pattern (that is, in the first pattern) which corresponds to the disposition of the first type electrode2ain the rear masking region R2, and when the substrate2comes into contact with the rear masking region R2, the hollow H completely stores the pastes Pst which is printed on the upper surface of the first type electrode2a. For this reason, during the secondary printing, the paste Pst printed on the first type electrode2ain the primary printing is prevented from coming into contact with the lower surface of the mask13.

When the substrate2comes into contact with the rear masking region R2of the mask13, the printing head17moves the front squeegee42F on the rear masking region R2by moving the front squeegee42F from the intermediate region Rm to the region on the rear side of the rear masking region R2(illustrated with an arrow E1inFIG. 18A). When the front squeegee42F is moved up to the rear region of the rear masking region R2, after the printing head17raises the front squeegee42F, now, the rear squeegee42R is lowered, and the lower end thereof abuts against the mask13. In addition, by moving the rear squeegee42R from the region on the rear side of the rear masking region R2to the intermediate region Rm, the rear squeegee42R is slidably moved on the rear masking region R2(illustrated with an arrow E2inFIGS. 18B and 19A). When the inside of each second type opening K2is filled with the paste Pst as the squeegee42slidably moves (FIG. 19A), the substrate holding and moving mechanism12lowers the substrate holding portion21, and the snapping-off is performed. Accordingly, a layer of the paste Pst having a thickness which corresponds to the thickness T2of the mask13of the rear masking region R2is formed on each second type electrode2bof the substrate2(FIG. 19B), and the secondary printing is finished.

In this manner, after the squeegee42slidably moves in the front masking region R1of the mask13, and the first type opening K1is filled with the paste Pst, the squeegee42stops in the intermediate region Rm between the front masking region R1and the rear masking region R2. After this, by starting the movement from the intermediate region Rm and slidably moving the rear masking region R2, the second type opening K2is filled with the paste Pst. In other words, the squeegee42(specifically, the front squeegee42F) is not separated from the mask13between a sliding operation on the front masking region R1and a sliding operation on the rear masking region R2. For this reason, it is possible to smoothly and efficiently print two types of pastes Pst (two types of thicknesses) having different thicknesses from each other.

In the above-described manner, when the paste Pst is printed on each electrode2D (the first type electrode2aand the second type electrode2b) on the substrate2, and the screen printing per one substrate2is finished, the substrate holding and moving mechanism12opens the pair of the clampers33and releases the held state of the substrate2. In addition, the positioning conveyor31is operated, the substrate2is delivered on the carrying-out conveyor15, and the carrying-out conveyor15carries out the received substrate2to the component mounting apparatus5on the upstream process side.

InFIG. 1, the component mounting apparatus5is provided with a substrate carrying conveyor71for carrying and positioning the substrate2, a parts feeder72which supplies the component3, and a mounting mechanism74which picks up the component3supplied by the parts feeder72by a mounting head73, and mounts the component3onto the substrate2positioned by the substrate carrying conveyor71. The component mounting apparatus5mounts the small-sized component, such as a chip component, on the first type electrode2a, and mounts the large-sized component, such as the connector, on the second type electrode2b. When mounting work of the component3with respect to the substrate2is finished, the component mounting apparatus5operates the substrate carrying conveyor71, and carries out the substrate2to the downstream process side. In this manner, the mounted substrate2J is manufactured by the component mounting line1.

Second Embodiment

FIG. 20illustrates the screen printing apparatus4according to a second embodiment of the present invention. The screen printing apparatus4according to the second embodiment has substantially the same operation during the screen printing as that of the screen printing apparatus4according to the first embodiment, but the configurations of the mask13are different from each other. In other words, the mask13of the screen printing apparatus4according to the second embodiment is provided with an inclination surface13S in which the upper surface of the intermediate region Rm in the mask13according to the first embodiment connects the upper surface of the front masking region R1and the upper surface of the rear masking region R2to each other (refer toFIG. 21). Accordingly, since the upper surface of the front masking region R1and the upper surface of the rear masking region R2are smoothly linked to each other, and the movement of the paste Pst on the mask13becomes smooth, a scraping operation of the paste Pst becomes smooth.

Third Embodiment

FIG. 22illustrates the screen printing apparatus4according to a third embodiment of the present invention. The screen printing apparatus4according to the third embodiment, also has substantially the same operation during the screen printing as that of the screen printing apparatus4according to the first embodiment, but the configurations of the mask13are different from each other. In other words, in the screen printing apparatus4according to the third embodiment, the upper surface of the front masking region R1and the upper surface of the rear masking region R2are the same plane, and the height of the upper surface of the front masking region R1and the height of the upper surface of the rear masking region R2are equivalent to each other (refer toFIG. 23). For this reason, similar to a case of the second embodiment, the movement of the paste Pst on the mask13becomes smooth, and a scraping operation of the paste Pst becomes smooth.

As can be ascertained fromFIGS. 22 and 23, in the third embodiment, the height of the lower surface of the rear masking region R2is lower than the height of the lower surface of the front masking region R1, and the step between both regions is formed on the lower surface side of the mask13. For this reason, when the substrate2is brought into contact with the front masking region R1, the rear clamper33R comes into contact with the inside of the front masking region R1(FIG. 24A). In addition, when the substrate2is brought into contact with the rear masking region R2, the front clamper33F comes into contact with the inside of the rear masking region R2(FIG. 24B). In the first embodiment and the second embodiment, the height when the substrate2comes into contact with the front masking region R1is the same as the height when the substrate2comes into contact with the rear masking region R2, but in the third embodiment, the height when the substrate2comes into contact with the front masking region R1is different from the height when the substrate2comes into contact with the rear masking region R2only by the amount of the step.

As described above, the screen printing apparatus4according to the above-described first to the third embodiments, includes the mask13which has the first type opening K1(first opening) in the front masking region R1(first region), and the second type opening K2(second opening) in the rear masking region R2(second region). In addition, the first type opening K1is filled with the paste Pst in a state where the substrate2is brought into contact with the front masking region R1, and then, the second type opening K2is filled with the paste Pst in a state where the substrate2is brought into contact with the rear masking region R2. According to this, it is possible to print two types of pastes Pst which have different thicknesses from each other on the substrate2. In other words, one mask13performs a function which corresponds to that of two masks, and only one prepared mask13may be employed. For this reason, according to the screen printing apparatus4according to the first to the third embodiments, it is possible to print two types of pastes Pst which have different thicknesses from each other without increasing the size of the apparatus.

In addition, in the above-described first to the third embodiments, the printing head17is provided with the squeegee42which slidably moves on the mask13, and fills the first type opening K1and the second type opening K2with the paste Pst, but the printing head17may not be necessarily provided with the squeegee42. For example, a printing head which moves on the mask13and fills the first type opening K1and the second type opening K2with the paste Pst while ejecting the paste Pst sealed in a cartridge may be employed. In this case, if the printing head fills the first type opening K1with the paste Pst, and then fills the second type opening K2with the paste Pst, the moving direction of the printing head17may be arbitrary. Furthermore, in the above-described first to the third embodiments, two regions (the first region and the second region) which have different thicknesses from each other are provided to be aligned in the longitudinal direction of the mask13, but this is merely an example, and may be provided to be aligned in a direction other than the longitudinal direction of the mask13.

There are provided a screen printing apparatus which can print two types of pastes which have different thicknesses from each other without increasing the size of the entire apparatus, and a component mounting line.