GB2521591A

GB2521591A - Print head

Info

Publication number: GB2521591A
Application number: GB1318969.1A
Authority: GB
Inventors: Michael Zahn
Original assignee: ASM Assembly Systems Switzerland GmbH
Current assignee: ASM Assembly Systems Switzerland GmbH
Priority date: 2013-10-27
Filing date: 2013-10-27
Publication date: 2015-07-01
Also published as: WO2015059297A1; GB201318969D0; TW201532844A

Abstract

A print head for use with a printing screen in printing patterns of deposits on work pieces W, the print head comprising an attachment member 3 by which the print head is mounted to a screen printing machine, and a support member 5 which is pivotably coupled to the attachment member 3 and is configured to support at least one blade 7a, 7b. The print head is displaceable over a printing screen PS in first and second opposite directions D1, (D2, Fig.5) and the support member 5 is pivotably coupled to the attachment member 3 between a first position when the print head is displaced in the first direction D1 and a second position when the print head is displaced in the second direction (D2, Fig.5). The attachment member 3 may include a coupling part (19, Fig.1) having a bore (21, Fig.1) which receives a rod (23, Fig.1) to which the support member 5 is attached so as to pivot about a first axis X relative to the attachment member 3.

Description

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PRINT HEAD

The present invention relates to a print head for use with a printing screen, often alternatively referred to as a stencil, in printing patterns of deposits on workpieces, especially electronic substrates, for example, wafers, such as for solar or fuel cells.

Various print heads exist, including squeegee-type designs which allow for a reciprocating printing operation in two opposite directions, such as disclosed by the applicant's earlier WO-A-2009/112841.

Whilst such a print head prints entirely satisfactorily, the present inventors have recognized that this existing squeegee-type print head requires a significant clear area between the edge of the image in the printing screen and the frame which supports the printing screen, in order to allow the operative squeegee or wiper blade to be driven beyond the edge of the image in a print stroke and the inoperative squeegee in that print stroke not to contact the supporting frame.

Accordingly, the present invention provides a print head for use with a printing screen in printing patterns of deposits on workpieces, the print head comprising an attachment member by which the print head is mounted to a screen printing machine, and a support member which is pivotably coupled to the attachment member and is configured to support at least one blade, wherein the print head is displaceable over a printing screen in first and *:..4 second opposite directions and the support member is pivotably coupled to the attachment member between a first position when the print head is * displaced in the first direction and a second position when the print head is displaced in the second direction.

* Preferred embodiments of the present invention will now be described ***.* * hereinbelow by way of example only with reference to the accompanying drawings, in which: Figure 1 illustrates a print head in accordance with a preferred embodiment of the present invention; Figure 2 illustrates a first vertical sectional view (along section I-I in Figure 1) of the print head of Figure 1; Figure 3 illustrates a second vertical sectional view (along section 11-Il in Figure 1) of the print head of Figure 1; Figure 4 illustrates a vertical sectional view of the print head of Figure 1 (along section 111-Ill in Figure 1) in operation in a first print stroke; and Figure 5 illustrates a vertical sectional view of the print head of Figure 1 (along section 111-Ill in Figure 1) in operation in a second print stroke, opposite in direction to the first print stroke.

The print head comprises an attachment member 3 by which the print head is mounted to a screen printing machine, and a support member 5 which is pivotably, here hingeably, coupled to the attachment member 3 between two operative positions, as illustrated in Figures 4 and 5, and supports first and second squeegee or wiper blades 7a, b.

In this embodiment the attachment member 3 comprises a body 11, here an elongate body, and an attachment 15 by which the print head is mounted to the screen printing machine.

* In this embodiment the body 11 comprises an attachment part 17 to which the attachment 15 is provided and a coupling part 19 by which the support *:°* member 5 is coupled to the attachment member 3.

***.** * In this embodiment the coupling part 19 includes a bore 21 which extends longitudinally therethrough and receives a rod 23 to which the support member 5 is attached so as to be pivotable about a first axis X. In this embodiment the coupling part 19 comprises at least one, here a plurality of projections 25a-c through which extend the bore 21 and define at least one, here a plurality of recesses 27a, b.

In this embodiment the attachment 15 comprises a bearing 31 which allows for rotation of the body 11 about a second axis Y which is orthogonal to the first axis X. In this embodiment the bearing 31 comprises first and second bearing elements 33a, b which are disposed to opposite sides of the body 11.

In this embodiment the attachment member 3 includes first and second engagement surfaces 35a, b, which act to limit the pivot angle 13 of the support member 5 relative to the attachment member 3, as will be described in more detail hereinbelow.

In this embodiment the engagement surfaces 35a, b are provided by surfaces of at least one of the projections 25a-c, here each of the projections 25a-c.

In this embodiment the support member 5 comprises a body 41, here an *:*.. elongate body, which comprises an attachment part 43 to which the wiper blades 7a, b are attached and a coupling part 45 by which the support fl S. * member 5 is coupled to the attachment member 3. *.** * *

*... In this embodiment the attachment part 43 comprises first and second *SSS * attachment surfaces 47a, b, here oppositely-directed surfaces, to which the **...

* first and second wiper blades 7a, b are attached, here in fixed, spaced relation.

In this embodiment the attachment surfaces 47a, b are inclined such that the wiper blades 7a, b are disposed in tapering relation, with the lower, screen-contact edges of the wiper blades 7a, b being in closest relation.

In an alternative embodiment the attachment surfaces 47a, b could be in parallel relation.

In this embodiment the coupling part 45 includes a bore 49 which extends longitudinally therethrough and receives the rod 23, by which the support member 5 is attached to the attachment member 3 so as to be pivotable about the first axis X. In this embodiment the coupling part 45 comprises at least one, here a plurality of projections 51a, b through which extend the bore 49 and define at least one, here a plurality of recesses 53a-c which receive the projections 25a-c of the attachment member 3.

In this embodiment the support member 5 includes first and second engagement surfaces 55a, b, which act to limit the pivot angle j3 of the support member 5 relative to the attachment member 3, as will be described in more detail hereinbelow.

In this embodiment the engagement surfaces 55a, b are provided by surfaces of at least one of the recesses 53a-c, here each of the recesses 53a-c.

* os 0 * In this embodiment the projections 25a-c, 51a, b and the recesses 27a, b, 53a-c are arranged such that the attachment member 3 and the support **.. member 5 have a fIxed relation in the first axis X. * * * 1 With this pivotable configuration of the support member 5, the print head allows for reciprocating operation in two opposite directions Dl, D2, as illustrated in Figures 4 and 5, and,, because of the relatively-close spacing of the wiper blades 7a, b along the printing axis, the print head can be used with a printing screen PS in which the image extends relatively close to the supporting frame.

In a first operative stroke, as illustrated in Figure 4, the print head is displaced in a first direction Dl over the surface of the printing screen PS, and the engagement of the forward wiper blade 7a with the printing screen PS causes the support member 5 to pivot about the first axis X in a first sense in relation to the attachment member 3 until the attachment member 3 and the support member 5 adopt a fixed angular relationship, here inclined at a first angle of inclination 13i, in which the first engagement surface 35a of the attachment member 3 abuts the first engagement surface 55a of the support member 5. This first angle of inclination 13i, which defines the angular relation of the forward wiper blade 7a to the surface of the printing screen PS, is maintained during displacement of the print head in the first direction Dl, and provides for the trailing wiper blade 7b to be held clear of the printing screen PS and thereby not interfere with the already-filled apertUres in the printing screen PS.

In a second operative stroke, as illustrated in Figure 5, which is of opposite direction to the first operative stroke, the print head is displaced in a second direction D2 over the surface of the printing screen PS, and the engagement of the forward wiper blade 7b, previously trailing in the first operative stroke, with the printing screen PS causes the support member 5 to pivot about the first axis X in a second sense, opposite to the first sense, in relation to the attachment member 3 until the attachment member 3 and the support member 5 adopt a second, fixed angular relationship, here inclined at a second angle of inclination 13z, in which the second engagement surface 35b of the attachment member 3 abuts the second engagement surface 55b of the support member 5. This second angle of inclination 132, * which defines the angular relation of the forward wiper blade 7b to the surface of the printing screen PS, is maintained during displacement of the print head in the second direction D2, and provides for the trailing wiper blade 7a, previously forward in the first operative stroke, to be held clear of the printing screen PS.

Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.

For example, in one embodiment, instead of coupling the support member 5 to the attachment member 3 by a pivot rod 23, the support member 5 could be coupled to the attachment member 3 by a flexible coupling.

In another modification, the print head could include only a single squeegee or wiper blade 7, with the front and rear faces of the wiper blade 7 providing the operative face in a respective one of the printing directions Dl, D2. In this embodiment the first and second angles of inclination F3, 13z are configured differently such that the angle enclosed between the forwardly-directed face of the wiper blade 7 and the printing screen PS in each of the printing directions Dl, D2 can be the same.

In one embodiment one of the blades 7 could function as a flood bar. ** * . * .

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Claims

CLAIMS1. A print head for use with a printing screen in printing patterns of deposits on workpieces, the print head comprising an attachment member by which the print head is mounted to a screen printing machine, and a support member which is pivotably coupled to the attachment member and is configured to support at least one blade, wherein the print head is displaceable over a printing screen in first and second opposite directions and the support member is pivotably coupled to the attachment member between a first position when the print head is displaced in the first direction and a second position when the print head is displaced in the second direction.
2. The print head of claim 1, wherein the attachment member comprises a body and an attachment by which the print head is mounted to a screen printing machine.
3. The print head of claim 2, wherein the body comprises an attachment part to which the attachment is provided and a coupling part by which the support member is coupled to the attachment member.
4. The print head of claim 3, wherein the coupling part includes a bore which extends longitudinally therethrough and receives a rod to which the support member is attached so as to be pivotable about a first axis relative to the attachment member.*
5. The print head of claim 4, wherein the coupling part comprises at least one projection, optionally a plurality of projections, through which extends the bore, and the at least one projection defines at least one recess, optionally a plurality of recesses. S...

S

S 55 55 S
6. The print head of any of claims 2 to 5, wherein the attachment comprises a bearing which allows for rotation of the body about a second axis which is orthogonal to the first axis.
7. The print head of any of claims 1 to 6, wherein the attachment member and the support member each include first and second engagement surfaces, and respective ones of the engagement surfaces of the attachment member and the support member when engaged act to limit a pivot angle (Pi, 132) of the support member relative to the attachment member when the print head is operated in a respective one of the first and second directions.
8. The print head of claim 7, wherein the engagement surfaces are provided by surfaces of at least one projection and at least one recess.
9. The print head of any of claims 1 to 8, wherein the support member comprises a body which comprises an attachment part to which the at least one blade is attached and a coupling part by which the support member is coupled to the attachment member.
10. The print head of claim 9, wherein the attachment part comprises first and second attachment surfaces, optionally oppositely-directed surfaces, to which first and second blades are in use attached. e * * .
11. The print head of claim 10, wherein the first and second blades are each squeegees. **.*. * *
12. The print head of claim 10, wherein one of the blades is a squeegee and the other of the blades is a flood bar, optionally inclined at about degrees to the printing screen.

****** * *
13. The print head of any of claims 10 to 12, wherein the first and second blades are attached in fixed, spaced relation.
14. The print head of any of claims 10 to 13, wherein the attachment surfaces have a spacing of not more than 25 mm, optionally not more than 20 mm.
15. The print head of any of claims 10 to 14, wherein the attachment surfaces are inclined such that the blades are disposed in tapering relation, with lower.edges of the blades being in closer relation.
16. The print head of any of claims 10 to 14, wherein the attachment surfaces are in parallel relation.
17. The print head of any of claims 10 to 16, wherein the coupling part includes a bore which extends longitudinally therethrough and receives the rod, by which the support member is attached to the attachment member so as to be pivotable about the first axis.
18. The print head of claim 17, wherein the coupling part comprises at least one projection, optionally a plurality of projections, through which extends the bore and the at least one projection defines at least one recess, optionally a plurality of recesses, which receives the at least one projection of the attachment member. *. ** * * * * *
19. The print head of any of claims 1 to 18, wherein projections and recesses of the attachment member and the support member are arranged such that the attachment member and the support member *:* have a fixed relation in the first axis. *o
20. The print head of any of claims 1 to 19, wherein, when the print head * is displaced in the first direction over the surface of the printing screen, engagement of one blade, forward in the first direction, with -10 -the printing screen causes the support member to pivot about the first axis in a first sense in relation to the attachment member until the attachment member and the support member adopt a fixed angular relationship, inclined at a first angle of inclination (13), and maintain this fixed angular relationship during displacement of the print head in the first direction, which provides for the other blade, trailing in the first direction, to be held clear of the printing screen.
21. The print head of claim 20, wherein, when the print head is displaced in the second direction over the surface of the printing screen, engagement of the other blade, forward in the second direction, with the printing screen causes the support member to pivot about the first axis in a second sense, opposite to the first sense, in relation to the attachment member until the attachment member and the support member adopt a fixed angular relationship, inclined at a second angle of inclination (P2), and maintain this fixed angular relationship during displacement of the print head in the second direction, which provides for the one blade, trailing in the second direction, to be held clear of the printing screen.
22. The print head of any of claims 1 to 21, wherein the support member is hinged to the attachment member about a pivot rod.
23. The print head of any of claims 1 to 22, wherein the support member is hinged to the attachment member by a flexible coupling.

*
24. The print head of any of claims 1 to 23, wherein the print head includes a single blade, with opposite faces of the blade providing an operative face in a respective one of the directions. *..*
25. The print head of any of claims 1 to 23, wherein the print head * includes first and second blades.

-11 -
26. The print head of any of claims 1 to 25, wherein the first and second angles of inclination 1', 132 are the same.
27. The print head of any of claims 1 to 25, wherein the first and second angles of inclination 13i, 32 are different.
28. The print head of any of claims 1 to 27, wherein an angle enclosed between the forward blade and the printing screen in each of the directions is the same.
29. The print head of any of claims 1 to 27, wherein an angle enclosed between the forward blade and the printing screen in respective ones of the directions is different.
30. A screen printing machine incorporating the print head of any of claims 1 to 29.
31. A method of screen printing using the print head of any of claims 1 to 29. *. .* * . . * ** ** * S. * 0 a *5***0 * aC -* 0 S... * **S*StSSS * S