US-12617198-B2 - Alignment of singulated substrates

US12617198B2US 12617198 B2US12617198 B2US 12617198B2US-12617198-B2

Abstract

Tooling for supporting workpieces during a printing operation, comprises a support tower comprising a base and a head, the head being positioned vertically above the base in use, the head being relatively moveable with respect to the base in a horizontal plane in use, the head having first and second support surfaces located at an upper end thereof, each of the first and second support surfaces being adapted to support a respective workpiece thereon, wherein the first support surface is relatively moveable with respect to the second support surface in a vertical direction in use between a printing configuration in which the first and second support surfaces are substantially coplanar in the horizontal plane, and a pre-printing configuration in which the first and second support surfaces are spaced in the vertical direction.

Inventors

Keith Michael HANSFORD
Simon Stuart PAPE

Assignees

ASMPT SMT SINGAPORE PTE. LTD.

Dates

Publication Date: 20260505
Application Date: 20230623
Priority Date: 20220623

Claims (16)

1 . Tooling for supporting workpieces during a printing operation, comprising: a support tower comprising a base and a head, the head being positioned vertically above the base in use, the head being relatively moveable with respect to the base in a horizontal plane in use, the head having first and second support surfaces located at an upper end thereof, each of the first and second support surfaces being adapted to support a respective workpiece thereon, wherein the first support surface is relatively moveable with respect to the second support surface in a vertical direction in use between a printing configuration in which the first and second support surfaces are substantially coplanar in the horizontal plane, and a pre-printing configuration in which the first and second support surfaces are spaced in the vertical direction; and wherein the tooling comprises means for moving the first support surface downwards relative to both the second support surface and the base as the tooling moves from the pre-printing configuration to the printing configuration, the means is an actuator operative to drive the first support surface or a projection for abutting with a limiting member.
2 . The tooling of claim 1 , wherein the head comprises at least one additional support surface, and wherein in respective pre-printing configurations the first and second support surfaces and each additional support surface are all spaced in the vertical direction.
3 . The tooling of claim 2 , wherein the first and second support surfaces and each additional support surface are arranged in a linear array on the head.
4 . The tooling of claim 2 , wherein the first and second support surfaces and each additional support surface are arranged in a two-dimensional matrix array on the head.
5 . The tooling of claim 1 , wherein the support tower comprises an actuator for driving the head in the horizontal plane relative to the base.
6 . The tooling of claim 5 , wherein the actuator is operative to drive the head in orthogonal X and Y directions within the horizontal plane, and also to rotate the head about a vertical axis.
7 . The tooling of claim 1 , wherein the first support surface is resiliently biased to the pre-printing configuration.
8 . The tooling of claim 1 , wherein the projection is located at the first support surface to abut the limiting member such that lifting of the first support surface is prevented during lifting of the support tower when the projection abuts with the limiting member.
9 . The tooling of claim 1 , wherein the actuator is a Z-axis actuator associated with the first support surface operative to drive the first support surface downwards relative to the second surface.
10 . A printing machine for printing workpieces at a printing location within the printing machine, comprising: a transport system configured to transport workpieces into the printing machine and to the printing location, and then, following completion of a printing operation, out of the printing machine; a printing screen support for holding a patterned printing screen above the printing location; a tooling table located underneath the printing location, the tooling table being driveable towards and away from the printing location; and the tooling of claim 1 mounted on the tooling table.
11 . The printing machine of claim 10 , wherein the transport system is configured to transport a carrier into the printing machine and to the printing location, and then, following completion of a printing operation, out of the printing machine, the carrier adapted to carry a plurality of workpieces.
12 . The printing machine of claim 10 , comprising a limiting member arranged to abut with the first support surface to limit the vertical position of the first support surface during upward driving of the tooling table.
13 . The printing machine of claim 12 , wherein the limiting member comprises at least part of a surround plate which comprises at least one aperture, the at least one aperture overlying a respective workpiece when in the printing location.
14 . The printing machine of claim 12 , wherein the limiting member comprises at least part of a referencing plate.
15 . The printing machine of claim 10 , comprising a camera system for determining the orientation of workpieces which have been transported to the printing position.
16 . The printing machine of claim 15 , wherein the camera system comprises a camera located at a vertical height between the transport system and the printing screen in use, optionally the camera is driveable in the horizontal plane to overlie and scan individual workpieces consecutively.

Description

This invention relates to tooling, a printing machine and a method of aligning workpieces prior to a printing operation. BACKGROUND AND PRIOR ART Industrial screen-printing machines typically apply a conductive print medium, such as solder paste or conductive ink, onto a planar workpiece, such as a circuit board, by applying the conductive print medium through a pattern of apertures in a printing screen (sometimes referred to as a foil or stencil) using an angled blade or squeegee. Where the area of the pattern is relatively small with respect to the area of the screen, it is possible to include more than one pattern within the screen, thus allowing more than one area of a board, or more than one board, to be printed simultaneously using the same screen. Alternatively, more than one relatively small screen may be used within the same printing machine to enable the more than one area of a board, or more than one board, to be printed simultaneously using respective screens. While such simultaneous printing may clearly be more efficient than sequential printing, there are problems associated with these techniques. i) Printing of More than One Area of a Board As noted above, it is possible to print a plurality or array of patterns onto respective areas of a single board or panel in a single print operation, to produce a plurality of printed circuit boards (PCBs) which may be subsequently physically separated. This technique is conceptually and technically simple—a panel with a plurality of boards is loaded into a printing machine, correctly aligned and then all the boards of the panel are printed simultaneously. However, with any circuit board there is a risk that at least part of that board may be defective, which in turn may lead to a defective PCB. This situation is schematically shown in FIG. 1, where three panels 1, 2, 3 are shown, each having a 4×1 array of boards A-D. While the left-most panel 1 is completely free from defects, the adjacent panel 2 has a defective board 2A, while the right-most panel 3 has a defective board 3B. It is inefficient to pre-check the circuit boards for defects and reject an entire panel if one board is found to be defective. It is also inefficient and problematic to print a pattern onto an identified defective board and reject the separated defective board subsequent to the printing process. One current solution to this problem is to identify defective boards before commencement of the printing operation, and sort the panels into separate batches having similar defects, for example a first batch which is defect-free, a second batch in which the left-most board is defective, a third batch in which the second-left board is defective and so on. A dedicated respective screen may then be used with each batch. For example, a screen having all four aperture patterns would be used for the first batch, while screens having only three aperture patterns would be used for each remaining batch. For the 4×1 array described here, this would result in the use of five different screens per panel to print on a side of the panel. Since each panel will typically be printed on both sides, this could lead to the use of ten different set-ups for a single panel type, rather than the optimal two (i.e. one for each side). In addition, the second to fifth batches will only be printing at 75% efficiency. Furthermore, if two or more boards are defective then additional measures must be taken. ii) Printing of More than One Board A solution to the above problem is to pre-separate or “singulate” the individual boards before the printing process. Here, any defective boards could be identified before printing and rejected immediately, so that only non-defective boards are printed. While this process is relatively efficient, it introduces complications. In particular, it is difficult both to support and to align individual relatively small boards for simultaneous (or sequential) printing. Various approaches have been developed to overcome these problems. For example, GB 2484373 A describes a method in which individual boards are respectively positioned, but this only permits the sequential printing of one substrate at a time. JP-2009-248551 describes a method in which the position of each board is checked individually, and each board is sequentially repositioned using a repositioning arm. While this technique permits all boards of a panel to be printed on simultaneously, additional apparatus (i.e. the positioning arm) is required, and moving the arm between workpieces is time-consuming. WO2014/166956 describes an alternative apparatus, in which all boards may be aligned simultaneously using a reference webbing, and then simultaneously printed. This solution works well, though will not be suitable if an incoming unprinted board is positioned too far from its correct position. A workpiece support assembly, capable of supporting and individually aligning a multiplicity of relatively small workpieces (commonly ref