JP3684987B2 - Squeegee head for screen printing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screen printing squeegee head for printing paste such as cream solder or conductive paste on a substrate.
[0002]
[Prior art]
In an electronic component mounting process, screen printing is used as a method for printing paste such as cream solder or conductive paste on a substrate. In this method, a mask plate in which pattern holes are formed according to a printing target portion is set on a substrate, and paste is printed on the substrate through the pattern holes of the mask plate by squeezing.
[0003]
As a screen printing squeezing method, a method using a sealed squeegee head is known. Unlike normal screen printing, this method uses a squeegee head provided with a paste storage container, instead of supplying the paste directly onto the mask plate. In this method, the paste is pushed into the pattern hole of the mask plate by pressurizing the paste in the paste storage container with the opening provided on the lower surface of the paste storage container being in contact with the mask plate. It is. Then, by sliding the squeegee head on the mask plate, each pattern hole is sequentially filled with paste.
[0004]
[Problems to be solved by the invention]
In this sealed squeegee head, since it is required that the pressurized paste is brought into contact with the screen mask only through the opening, it is necessary to prevent the pressurized paste from protruding outside the opening as much as possible. However, the conventional sealed squeegee head has the following problems. Hereinafter, description will be given with reference to the drawings. 6A and 6B are partial cross-sectional views of a conventional screen printing squeegee head.
[0005]
In FIG. 6A, the squeegee head A includes two plate-like scraping members B and C on the lower surface, and a space between the scraping members B and C is a printing space for storing a paste to be printed. It has become. A closing member D is disposed at both side ends of the printing space in contact with the inner surfaces of the scraping members B and C. As shown in FIG. 6 (b), the paste stored in the squeegee head A comes into contact with the screen mask E through the opening between the two scraping members B and C, and the pattern holes of the screen mask E are applied by pressurization. Filled. The closing member D abuts against the inner surfaces of the scraping members B and C, thereby preventing the paste pressed during printing from leaking outside from the printing space.
[0006]
However, since the scraping members B and C are pressed against the screen mask E during printing and are bent, the contact surfaces of the scraping members B and C and the closing member D are in a completely intimate contact state. Instead, as shown in FIG. 6B, the gap S is generated when the squeegee head A is lowered and the scraping members B and C are pressed against the screen mask E. For this reason, the leakage of the paste from the squeegee head A at the time of printing cannot be prevented completely, and there has been a problem that printing failure tends to occur.
[0007]
Therefore, an object of the present invention is to provide a squeegee head for screen printing that can prevent paste leakage and ensure stable printing quality.
[0008]
[Means for Solving the Problems]
The squeegee head for screen printing according to the present invention is a screen for printing paste on a substrate through a pattern hole of the mask plate by storing the paste inside and sliding on the mask plate in a state where the paste is pressurized. A squeegee head for printing, a paste storage section for storing paste, paste pressurizing means for pressing the paste in the paste storage section, and a printing space for storing the pressed paste and contacting the surface of the mask plate And two scraping members which form front and rear walls in the squeezing direction of the printing space and whose lower end portions are provided in contact with the surface of the mask plate, and the printing at both end portions of the two scraping members. a closing member made of an elastic material which closes the space under the scraping member to the mask plate side of said closure member And a sliding member provided so as to protrude by a predetermined distance downward from the parts, before Symbol sliding member said scraping the closure member by the action of compressive load to the closure member by pressing the screen mask The contact surface between the scraping member and the closing member is sealed by pressing against the member .
[0009]
According to the present invention, the sliding member is provided on the mask plate side of the closing member so as to protrude downward by a predetermined dimension from the lower end of the scraping member, and the sliding member is pressed against the screen mask. By applying a compressive load to the closing member, the closing member is pressed against the scraping member to seal the contact surface between the scraping member and the closing member, thereby making the scraping member flexible. The paste can be prevented from leaking without obstructing and with a simple structure.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. 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 an embodiment of the present invention, and FIG. 3 is a screen printing apparatus according to an embodiment of the present invention. FIG. 4A is a partially inverted perspective view of a screen printing squeegee head according to an embodiment of the present invention, and FIG. 4B is a screen printing according to an embodiment of the present invention. FIG. 5 is a partial cross-sectional view of a squeegee head for screen printing according to an embodiment of the present invention.
[0011]
First, the structure of the screen printing apparatus will be described with reference to FIGS. 1 and 2, the substrate positioning unit 1 is configured by disposing a substrate holding unit 2 on a moving table (not shown). The substrate 3 to be screen-printed is held by a clamper 4 of the substrate holding unit 2, and the substrate 3 held by the substrate holding unit 2 is positioned in the horizontal direction and the vertical direction by driving a moving table (not shown). .
[0012]
A screen mask 10 is disposed above the positioning unit 1. The screen mask 10 is configured by mounting a mask plate 12 on a holder 11, and a pattern hole 12 a corresponding to a printing portion of a substrate 3 to be printed is opened in the mask plate 12.
[0013]
A squeegee head 13 is disposed on the screen mask 10 so as to be movable up and down by a head lifting unit 20. The head elevating unit 20 includes a cylinder 22 erected on a plate member 21, and a squeegee head 13 is coupled to a lower end portion of a rod 22 a of the cylinder 22 via a coupling member 15. By driving the cylinder 22, the squeegee head 13 moves up and down with respect to the mask plate 12. The head elevating unit 20 is an elevating unit that elevates and lowers the squeegee head 13 with respect to the screen mask 10.
[0014]
Sliders 23 are fixed to both ends of the lower surface of the plate member 21 of the head elevating unit 20, and the sliders 23 are slidably fitted to guide rails 24 disposed on the upper surface of the frame 25. A nut 26 is coupled to the lower surface of the plate member 21, and a feed screw 27 screwed into the nut 26 is driven to rotate by a motor 28.
[0015]
By driving the motor 28, the plate member 21 moves horizontally, and therefore the squeegee head 13 coupled to the head elevating unit 20 also moves horizontally. By driving the motor 28 with the squeegee head 13 lowered, the squeegee head 13 moves horizontally on the mask plate 12. That is, the motor 28, the feed screw 27 and the nut 26 are moving means for moving the squeegee head 13 horizontally on the mask plate 12.
[0016]
Below the squeegee head 13, there is provided a printing unit 14 that contacts the surface of the mask plate 12 and fills the pattern holes 12 a with cream solder 5 that is a paste. The structure of the printing unit 14 will be described with reference to FIG. In FIG. 3, reference numeral 30 denotes a main body, which is a block-like member that is elongated in the width direction of the mask plate 12. The length of the main body 30 is set so as to cover the width of the substrate 3 to be printed as shown in FIG. The main body 30 is formed with a recess 30a in which the cartridge 31 storing the cream solder 5 is detachably mounted.
[0017]
The cartridge 31 is a storage portion (paste storage portion) of the cream solder 5 in which a predetermined amount of the cream solder 5 is stored in advance, and is attached to the main body portion 30 during printing. A pressure plate 32 that pressurizes the internal cream solder 5 is fitted into the opening on the upper surface of the cartridge 31. The pressure plate 32 is coupled to the rod 16 a of the cylinder 16 disposed above, and the pressure plate 32 moves up and down within the cartridge 31 by driving the cylinder 16.
[0018]
The bottom surface of the cartridge 31 is an extrusion plate 31a for the cream solder 5, and the extrusion plate 31a has a large number of openings 31b. By pressing the pressure plate 32 downward by the cylinder 16, the cream solder 5 in the cartridge 31 is pressurized and pushed downward through the opening 31b of the extrusion plate 31a. The cylinder 16 and the pressure plate 32 serve as a pressure unit that pressurizes the cream solder 5.
[0019]
A diaphragm plate 34 provided with a large number of openings 34 a is mounted on the bottom of the main body 30 in the same manner as the extrusion plate 31 a of the cartridge 31. When the cream solder 5 is pushed out by the cylinder 16, it passes through the opening 31b of the extrusion plate 31a and the opening 34a of the diaphragm plate 34 in two stages and moves downward. The extruded cream solder 5 is a space formed below the main body 30, that is, two scraping members 36 </ b> A and 36 </ b> B disposed obliquely inward at the bottom of the main body 30 and the lower surface of the main body 30. To the print space 35 surrounded by.
[0020]
The scraping members 36 </ b> A and 36 </ b> B form front and rear walls in the squeezing direction of the printing space 35, and the lower ends of the scraping members 36 </ b> A and 36 </ b> B abut on the surface of the mask plate 12 when the squeegee head 13 is lowered. During the printing operation, the printing space 35 accommodates the pressurized cream solder 5, and the cream solder 5 is brought into contact with the surface of the mask plate 12 through the opening between the scraping members 36A and 36B.
[0021]
By pressing down the pressure plate 32 to pressurize the cream solder 5 in the cartridge 31, the cream solder 5 moves through the extrusion plate 31 a and the diaphragm plate 34 into the printing space 35. In the middle of the path of movement of the cream solder 5, there is a narrowed portion whose cross-sectional area is narrowed by a large number of small openings 31b, 34a. The viscosity of the solder 5 is lowered and modified to a property suitable for screen printing.
[0022]
In screen printing, the internal cream solder 5 is pressurized by the pressure plate 32, and the squeegee head 13 in a state in which the cream solder 5 modified to an appropriate viscosity as described above is filled in the printing space 35 is used as a mask. Slide on plate 12. Thereby, the cream solder 5 in the printing space 35 is filled into the pattern hole 12a of the mask plate 12 through the opening between the scraping members 36A and 36B.
[0023]
Then, by moving the squeegee head 13, the cream solder 5 is sequentially filled into each pattern hole 12a. If the cream solder 5 is filled in all the pattern holes 12a, the substrate holding part 2 is lowered to release the plate. That is, the cream solder 5 in the pattern hole 12a descends together with the substrate 3 and is separated from the pattern hole 12a, whereby the screen printing of the cream solder 5 on the substrate 3 is completed.
[0024]
Next, the structure of the side end portion of the printing space will be described with reference to FIG. 4A, a printing space 35 formed on the lower surface of the main body 30 of the squeegee head 13 (the upper surface side in FIG. 4A showing the inverted state) is skied by two scraping members 36A and 36B. The front and rear surfaces in the ging direction are enclosed. Closing members 37 are provided at both ends of the printing space 35 in the squeezing direction. The closing member 37 is sandwiched between the two scraping members 36 </ b> A and 36 </ b> B, and is held in the printing space 35 by a stop member 38 provided on the side surface side. The blocking member 37 prevents the cream solder 5 in the printing space 35 from leaking outside.
[0025]
As shown in FIG. 4B, the closing member 37 is a substantially trapezoidal columnar molded member made of an elastic material such as urethane rubber, and includes a trapezoidal short bottom surface 37a, two side inclined surfaces 37b, and a trapezoidal surface 37c on one side. A hollow member having four surfaces. That is, the trapezoidal long bottom surface (upper surface in the mounted state) 37d and the other trapezoidal surface (center side surface in the mounted state) 37e are open. A sliding member 39 having excellent self-lubricating properties such as a Teflon plate is attached to the lower surface (the surface corresponding to the trapezoidal short bottom surface 37a) in the mounted state. The sliding member 39 contacts the upper surface of the mask plate 12 during printing. By using a self-lubricating material for the contact surface, the squeegee head 13 can be moved smoothly during printing.
[0026]
The mounting state of the blocking member 37 will be described with reference to FIG. 5 showing the AA cross section of FIG. As shown in FIG. 5A, the closing member 37 is mounted along the inner surfaces of the two scraping members 36A and 36B, and the upper surface (the trapezoidal long bottom surface) of the closing member 37 is attached to the main body 30 in the mounted state. It is in a state of being pressed against the fixed receiving member 40. When the squeegee head 13 is lifted from the mask plate 12 and the lower ends of the scraping members 36A and 36B are separated from the mask plate 12, the sliding member 39 adhered to the lower surface is the lower ends of the scraping members 36A and 36B. The shape and dimensions are set so as to protrude downward from the portion by a predetermined dimension h.
[0027]
Next, the function of the closing member 37 will be described. In a state where the squeegee head 13 is lowered onto the mask plate 12 and the scraping members 36A and 36B are pressed against the mask plate 12, the sliding member 39 that was initially in the protruding state as shown in FIG. And the mask plate 12 are pressed and located on the same line as the lower ends of the scraping members 36A and 36B. That is, a vertical compressive load is applied to the closing member 37 by the pressing force of the squeegee head 13.
[0028]
When this compressive load is applied, the closing member 37, which is made of a flexible elastic material and is a hollow member, is deformed by the compressive load in the vertical direction, and the side inclined surfaces 37b are displaced laterally. This lateral displacement acts to press the closing member 37 against the inside of the scraping members 36A and 36B, that is, to seal the contact surface between the scraping members 36A and 36B and the closing member 37.
[0029]
In other words, in the present embodiment, the configuration in which the compressing load is generated on the closing member 37 by pressing the closing member 37 against the mask plate 12 seals the contact surface between the scraping members 36 </ b> A and 36 </ b> B and the closing member 37. Corresponds to sealing means. The shape / material of the closing member 37 is not limited to the above example, and the shape / material is such that a pressing force is generated against the contact surface with the scraping members 36A, 36B when pressed against the mask plate 12. Any material can be used.
[0030]
As a result, even when the lower end portions of the scraping members 36A and 36B are pressed against the mask plate 12 during screen printing and are deformed as shown in FIG. Following contact with the deformation, the contact portions with the scraping members 36A and 36B can be kept sealed. Therefore, the cream solder 5 pressurized from the printing space at the time of screen printing does not leak out, and it is possible to prevent the extra cream solder 5 from adhering.
[0031]
【The invention's effect】
According to the present invention, the sliding member is provided on the mask plate side of the closing member so as to protrude downward by a predetermined dimension from the lower end of the scraping member, and the sliding member is pressed against the screen mask. Since the contact member between the scraping member and the closing member is sealed by pressing the closing member against the scraping member by applying a compressive load to the closing member, the flexibility of the scraping member is hindered. In addition, the paste can be prevented from leaking with a simple structure, and stable printing quality can be ensured.
[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 a screen printing apparatus according to an embodiment of the present invention. 4 is a partial cross-sectional view of the squeegee head of the apparatus. FIG. 4A is a partially inverted perspective view of the screen printing squeegee head according to the embodiment of the present invention. FIG. FIG. 5 is a partial sectional view of a screen printing squeegee head according to an embodiment of the present invention. FIG. 6 is a partial sectional view of a conventional screen printing squeegee head.
3 Substrate 5 Cream solder 12 Mask plate 12a Pattern hole 13 Squeegee head 14 Printing unit 16 Cylinder 20 Head elevating unit 22 Cylinder 31 Cartridge 32 Pressure plate 35 Print space 36A, 36B Scraping member 37 Closure member

Claims (1)

A squeegee head for screen printing that prints paste on a substrate through a pattern hole of the mask plate by storing the paste inside and sliding on the mask plate in a state where the paste is pressurized. Paste storage section for storing, paste pressurizing means for pressurizing the paste in the paste storage section, printing space for storing the pressurized paste and contacting the surface of the mask plate, and before and after the squeezing direction of the printing space Two scraping members that form a wall and whose lower end is in contact with the surface of the mask plate; and a blocking member made of an elastic material that closes the printing space at both side ends of the two scraping members; , set so as to protrude by a predetermined distance downward from the lower end of the scraping member to the mask plate side of said closure member It was a sliding member, and obstruction before SL sliding member said scraping member against said closure member relative to the scraping member by by pressing the screen mask Ru by applying a compressive load to the closure member A squeegee head for screen printing, wherein a contact surface with a member is sealed.

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