EP2520143A1

EP2520143A1 - A component mounting machine

Info

Publication number: EP2520143A1
Application number: EP10805218A
Authority: EP
Inventors: Robert Axelsson; Peter SUNDSTRÖM; Erik ESKÅNG; Roger Jonasson; Lars Nygren
Original assignee: MyData Automation AB
Current assignee: Mycronic Technologies AB
Priority date: 2009-12-30
Filing date: 2010-12-30
Publication date: 2012-11-07
Also published as: WO2011079956A1; JP2013515363A; KR20120120933A; CN102742378A; WO2011079956A4

Abstract

A component mounting head arranged to pick up components at a picking position and place the components at a mounting position, the component mounting head comprising a plurality of nozzles, which are vertically movable downwards and upwards for enabling said picking and placing, wherein the component mounting head is arranged to control a plurality of picking operations including at least picking a single component with each nozzle and picking a single component with at least two nozzles in common.

Description

A COMPONENT MOUNTING MACHINE

Technical field

This invention relates to a component mounting machine, a mounting head and methods of mounting components, where technology of pick and place is employed.

Technical background

Machines for pick-and-place mounting of components on a substrate, such as a Printed Circuit Board (PCB), or a substrate for a System in Package (SiP) component are subject to different, often contradictory demands, such as mounting speed, mounting precision, size, prize, etc. The expression "pick and place" is understood by the person skilled in the art as describing the very mounting operation where a mounting head is moved to a component feeder area, where the mounting head picks one or more components from one or more of the component feeders, and then is moved to a mounting area where the mounting head places the component or components on the substrate. One principal example of a conventional prior art component mounting machine is shown in Fig. 1 of the attached drawings. It comprises a machine frame 1 , a component feeding device 3, including a plurality of component feeders, and arranged at a component feeder area of the machine frame 1 , a gantry system 5 having a first beam, or X beam, 7, and a second perpendicular beam, or Y beam, 9, attached to the machine frame 1, a mounting head 11 movably attached to the X beam 7, and a board transportation system 13, attached to the machine frame 1. The component feeding device 3 presents electronic components to the mounting head 1 1. The board transportation system 13 transports substrates between a conveyor line and a working area of the component mounting machine. The mounting head 1 1 is movable along the X beam 7 and the X beam is movable along the Y beam 9. Thereby, the gantry system 5 makes it possible to move the mounting head 1 1 between the component feeding device 3 and the substrate. Further, the mounting head 1 1 is movable in the vertical direction, and is also able to rotate around a vertical axis. It also contains a suction device. This makes it possible to pick up, by activating the suction device, electronic components from the component feeding device 3, transport them to the substrate, and release them at a precise location on the substrate. During the transport from pick up to the substrate a vision centering device 15 is passed to get an accurate position of picked components. The component feeding device 3 typically is desired to have a large capacity, i.e. it should be possible to load many different component reels in the device. This requires quite a lot of space for the component feeding device. Further it is desirable that the gantry system and the mounting head are both fast and very accurate.

Therefore it is desired to have the gantry system as small as possible, since a large system will have more mass, which require more powerful motors, which in turn leads to more heat generation in the system. The heat generation makes it hard to get a very accurate system, since effects from thermal expansion needs to be handled somehow.

On the other hand, in a traditional pick and place machine, the gantry system needs to be large enough to be able to reach all parts of the component feeding device. Another aspect is that the mounting head may have to change picking tools every now and then to be able to pick all kinds of components, which may differ a lot in size, shape, and weight.

Summary of the invention

The object of this invention is to provide a solution that enables a more versatile and efficient pick and place operation.

The object is achieved by the component mounting head, the component mounting machine, and the method as defined in the enclosed claims.

Thus, according to one aspect of the present invention, there is provided a component mounting head arranged to pick up components at a picking position and place the components at a mounting position. The component mounting head comprises a plurality of nozzles, which are vertically movable downwards and upwards for enabling said picking and placing. The component mounting head is arranged to control a plurality of picking operations including at least picking a single component with each nozzle and picking a single component with at least two nozzles in common. By having the possibility of using more than one nozzle for picking a single component, the size of the nozzles can be adapted to small components, without having to be exchanged before picking a large component. Consequently, the component mounting head provides for a capability of handling of components differing a lot in size without the need of changing picking tools, e.g. nozzle tooltips or nozzles, thereby making the pick and place operation of the component mounting machine more versatile and efficient.

Brief description of the drawings Exemplifying embodiments of the invention will be described below with reference to the accompanying drawings, in which:

Fig. 1 shows a prior art component mounting machine;

Fig. 2 schematically illustrates parts of a component mounting operation according to an embodiment of the present invention;

Fig. 3 is a schematic perspective view of an embodiment of a mounting head according to the present invention;

Fig. 4 is a schematic sectional view of a part of the mounting head in fig. 3;

Figs. 5 to 7 schematically illustrates different component picking conditions and different embodiments of the mounting head according to the present invention;

Figs. 8a to 8d illustrate an operation sequence performed by an embodiment of a mounting head according to the present invention;

Fig. 9 is a schematic perspective view of an embodiment of a component mounting machine according to the present invention;

Fig. 10 to 12 are schematic plan views of an embodiment of the component mounting machine;

Fig. 13 is a schematic perspective view of an embodiment of a mounting head according to the present invention; and

Figs. 14 and 15 schematically illustrates further component picking

conditions.

Description of embodiments

The object of this invention is to provide a solution that enables a more versatile and efficient pick and place operation. The object is achieved by the component mounting head, the component mounting machine, and the method as defined in the enclosed claims.

The flexible and versatile component mounting head of the present invention is arranged to control a plurality of picking operations including at least picking a single component with each nozzle and picking a single component with at least two nozzles. By having the possibility of using more than one nozzle for picking a single component, the size of the nozzles can be adapted to small components, without having to be exchanged before picking a large component. Consequently, the component mounting head provides for a capability of handling components of different sizes without the need of changing picking tools, e.g. nozzle tooltips or nozzles, thereby making the pick and place operation of the component mounting machine more flexible and efficient for versatile operation by increasing the overall yield of the machine. According to an embodiment of the component mounting head, a nozzle tip impact detector is arranged to detect nozzle tip impact against a surface, wherein the nozzle tip is a bottom end of the nozzle.

According to an embodiment of the component mounting head, it comprises a nozzle holder, which includes a vertically movable nozzle guide, wherein the nozzle tip impact detector is attached to the nozzle guide and detects nozzle movement relative to the nozzle guide.

According to an embodiment of the component mounting head it further comprises a nozzle tip position detector, arranged to detect the vertical position of each nozzle tip, wherein the nozzle tip is a bottom end of the nozzle.

According to an embodiment of the component mounting head, it further comprises a nozzle group synchronizer for synchronizing the nozzles of at least one nozzle group, consisting of at least two nozzles, for picking a single component. It may happen that the nozzles are not fully synchronized, for example as regards the vertical movement thereof or the distance to the surface of the component, or that surface is not fully plane. Then the nozzle group synchronizer is advantageous.

According to an embodiment of the component mounting head one way of performing the synchronization is by means of an individual vertical movement servo motor of each respective nozzle and a servo controller controlling the servo motors.

According to an embodiment of the component mounting head, it comprises a nozzle holder, which includes a vertically movable nozzle guide, wherein the nozzles are held in one of an inactive position and an active position, wherein a nozzle, when in the active position, is downwardly spring biased against a seat of the nozzle guide. Thus, the spring biasing urges the nozzles to follow the nozzle guide downwards, and when impacting the component surface the spring biasing allows the nozzle to be retracted from the nozzle guide if it continues to move downwards thereby eliminating a risk of nozzle damage.

According to an embodiment of the component mounting head, it comprises a component grip tool, which is attached to a plurality of nozzle tips and which is controllable for vertical movement and for grip operation by means of controlling the nozzles the nozzle tips of which are attached to the component grip tool. This grip tool is useful for picking components having odd shapes which are not suitable to pick with a suction nozzle.

According to another aspect of the present invention there is provided a method of controlling nozzles of a mounting head arranged to pick up components at a picking position and place the components at a mounting position, comprising: - vertically moving the nozzles downwards and upwards for performing said picking and placing, thereby performing one or more of a plurality of picking operations including picking a single component with one nozzle and picking a single component with at least two nozzles in common.

According to an embodiment of the method it comprises rotating the mounting head, after having performed the component picking, and passing a vision centering device during movement to the mounting position. This is particularly advantageous when several components have been picked in a line. By rotating the mounting head the components can be moved passed the vision centering device in a series rather than in parallel.

According to a further aspect of the present invention there is provided a component mounting machine comprising a component feeder area; a board transportation system, arranged to hold a substrate at a substantially fixed position within a working area of the component mounting machine; a component mounting head as defined above; and a gantry system, carrying the mounting head and being arranged to move the mounting head for performing the picking and placing of components.

Further objects and advantages of the present invention will be discussed below by means of exemplary embodiments.

Referring to Fig. 3 an embodiment of the component mounting head 300 comprises a mounting head body 301, a vacuum controller 303, rotatably attached to the mounting head body 301, a rotatable nozzle holder 305 comprising a nozzle selection unit 307 attached to the vacuum controller 303, and a nozzle guide 309, which is rotatably carried by a vertically movable frame element 311, and a plurality of nozzles 313, held by the nozzle holder 305. The nozzle guide 309 is vertically movable by means of the frame element 311, while the nozzle selection unit 307 is vertically fixed.

As is evident from Fig. 4 the nozzles extend through holes in the nozzle guide 309. An upper end of each nozzle 313 is inserted into the nozzle selection unit 307. Each nozzle 313 is provided with a spring 315 extending between a bottom surface 317 of the nozzle selection unit 307 and a spring seat 319 provided by a flange 321 encircling the nozzle and located between the bottom surface of the nozzle selection unit 307 and a top surface of the nozzle guide 309. The nozzle 313 is spring biased towards the nozzle guide 309 due to the spring 315, and can be regarded as spring biased against a seat of the nozzle guide 309. In an inactive state the nozzle 313 is retained by the nozzle selection unit 307. In an active state the nozzle 313 is released from the nozzle selection unit 307. Consequently, when moving the nozzle guide 309 downwards those nozzles being in the inactive state, such as the leftmost nozzle in Fig. 4, are retained by the nozzle selection unit 307, while those nozzles 313 being in the active state follow the nozzle guide 309 downwards. This nozzle movement is indeed caused by the gravity alone, but in order to assure that the nozzle does not get stuck the spring biasing urges the nozzle 313 in the same direction. Further, the component mounting head 300 comprises an impact detector 323, arranged to detect nozzle tip impact against a surface, typically a top surface of a component 327. In this embodiment the impact detector is a nozzle movement detector 323, which for example is mounted at said flange 321 , or at the nozzle guide 309. Each nozzle 313 has a nozzle tip, or tooltip, 325 embodying its bottom end. The tooltip 325 is exchangeable, and it is typically exchanged when becoming worn. When starting to pick components the vertically movable frame element 31 1 is in its upper position where nozzles 313 are selected using the nozzle selection unit 307. Before vertical movement for component pick up the nozzle holder 305 is rotated to a desired angle. Nozzles to be used are then released in the vertical direction using the nozzle selection unit 307. Selected nozzles will follow the vertical movement of the movable frame element, or Z-frame, 31 1 by the individual nozzle springs 315 forcing the released nozzles 313 down onto the nozzle guide 309. When the Z-frame moves down the movement detector 323 will sense whether any nozzle 313 is stopped as a relative movement between the nozzle 313 and the nozzle guide 309. The downwards movement of the Z-frame 311 will be stopped when one or more nozzles 313 get mechanical contact with a component 327, depending on whether it has been determined that one or more nozzles 313 are going to be used for lifting the component (components) 327. When a nozzle is stopped the related vacuum valve, included in the vacuum controller 303, activates and one or more components are sucked onto one or more nozzles. Picking multiple components can be performed simultaneously or in separate sequences. Picking one component 327 can be performed using one or more nozzles, and can be synchronized with a nozzle group synchronizer. When picking is done, the mounting head 300 is moved horizontally to the placing area above the substrate, e.g. PCB, 329 with all components vertically lifted. During this movement a centering device, such as a vision centering device 203 as shown in Fig. 2, will detect the position of picked components to get a correct mounting position of each component. Mounting is performed in a similar way as picking. In the upper position, nozzles to be used are selected and rotated before vertical movement down onto the PCB 329. When the component 327 gets in contact with the PCB 329, the vacuum valve of the vacuum controller 303 is deactivated and the component 327 released onto the PCB 329. With this multi nozzle mounting head 300, multiple nozzles 313 can be used per handled component. This will reduce the number of different tooltips 325 needed to handle a wide component range, from small components to large components. Normally the size of the tooltips needs to be matched to the size of the components. When handling a large component with a single nozzle the tooltip needs to be sized to get enough vacuum force and a large enough contact area. The vacuum force is needed to be able to move and rotate the component. The supporting area is needed to get a stable vertical movement without risking that the mass forces cause the component to tilt and then loose suction. The tooltip must not be too large, because when using a large tooltip handling a small component there is a risk that the component can partly go into the vacuum hole in the tooltip, this would cause the machine to fail placing the component correctly. Changing tooltips takes time in a pick and place machine, so changing tool tips will reduce mounting speed of the machine. If a lot of different tooltips are needed to be able to place all components on a PCB, this will also add extra tooltip cost for the placements. So reducing the number of tools needed and thereby the tool changes needed is important both for increasing mounting speed and reducing cost.

In accordance with this invention, instead of using a large tooltip it is possible to use two or more nozzles with small tooltips. By using a number of small tooltips, the vacuum and supporting area will be equivalent to that of one nozzle with a larger tooltip. Picking a single component with a group of nozzles can be synchronized with a nozzle group synchronizer.

To get a pick and place component mounting machine to place more components in a shorter time, multiple nozzles can be used. By using multiple nozzles it is possible to pick and place a plurality of components on every cycle from component pick up, passing of vision centering device and placing of components. With a plurality of components per cycle, time spent on each component is reduced and therefore the machine will mount components faster. When using multiple nozzles during pick, the fastest way to pick up components is by picking with all nozzles at the same time, from now on called multiple pick. To be able to perform multiple picks, the spacing between nozzles and components in the feeding device needs to be essentially the same and the orientation of the line with mount head nozzles and components in the component feeding device needs to be essentially the same. Traditionally when having a large number of mounting head nozzles arranged for multiple pick and using a line sensor vision device, the line sensor need to be long enough to capture the outline of all components picked. This is because the orientation of the line of components in the component feeding device is orthogonal to the preferred moving direction from the component feeding device to the PCB. Having a long line sensor is expensive and space consuming. In accordance with this invention the spacing of nozzles can be minimized, every individual nozzle does not need a separate rotation mechanism which saves space. Another advantage is the possibility to rotate the nozzles orthogonally orientated compared with the orientation of the line sensor in the vision centering device. With this orientation when passing the vision centering device, the line sensor length needed to capture the outline of all components is minimized, or optimized for a more versatile operation than possible in component mounting machines of today, saving space and reducing cost of the device. Also when using this orientation the light levels used by the vision centering device can be adjusted individually for every component, which also contributes to a pick and place operation of the component mounting machine that is more flexible and versatile. This is illustrated in Fig. 2, where the mounting head 201 picks several components side by side at a picking position 207, rotates 90 degrees before passing the vision centering device 203, and passes the vision centering device in that rotational position on its way to the PCB 205, where it is going to place each component in a mounting position 209. This means that the picked components pass the vision centering device 203 in a series rather than in parallel.

Advantages of sharing rotation mechanism are that there is more space in the mounting head and the cost is lowered. These released resources can be used to achieve high accuracy and performance. For example:

• Higher resolution of a rotational position encoder

• Large rotational bearings with preload to avoid mechanical play

• Larger motor and gear performing rotation

Summarily, the multi nozzle mounting head has only one rotational movement, all nozzles rotate around the same axis, and there are no individual rotational movements of nozzles.

The vertical movement of nozzles can be implemented with

• Individual actuators

· A common movement actuator combined with a nozzle selection unit.

• A combination of individual movement actuator and a common movement actuator

Traditionally a multi nozzle mounting head with a number of nozzles with small spacing between them are suitable for mounting small components at high speeds and limited accuracy. As described above, a multi nozzle mounting head can also be used for placing large components with high accuracy. When utilizing multiple nozzles for picking and placing a component it is important wdth low level variations of nozzles used. The attraction force will be lower between nozzles and component if there is large variation of nozzle levels.

Referring to Fig. 5, nozzle level variations, i.e. the nozzles 325 have been moved to different heights due to some inaccuracy, can cause air leakage between nozzles 325 and component 327 and also reduce contact area between nozzles 325 and component 327, this is because there may be an angle error between nozzle surface and component surface. In worst case the component 327 is dropped before mounting thereof, or it is not possible to pick the component 327. To minimize these negative effects the mechanical tolerances on nozzle lengths and tooltips used must be high when using a nozzle group synchronizer providing mechanical nozzle synchronization. When using servo synchronized nozzle movements, the servo controller must be operated with high accuracy. The servo synchronized nozzle movements can adapt for any mechanical differences between nozzles or components upper surface, this is an advantage compared with mechanical synchronization of nozzles. With servo synchronization it is possible to compensate for individual nozzle lengths, components with top surface having different heights, tooltips with different lengths and also compensate for wear of tooltips. Nozzles including tooltips can be measured during tooltip change and any differences can be compensated for when performing synchronized pick and place. The servo synchronization is for example obtained by providing each nozzle 1303 with an individual servo motor 1305 for the vertical movement, and providing a servo controller 1307 controlling the servo motors 1305, as schematically illustrated in Fig. 13. The servo motors 1305 are arranged at an appropriate position of the mounting head somewhere above the nozzle guide 1309, which is vertically fixed while still rotatable. In this embodiment the nozzle tip impact detector mentioned above typically is arranged to detect the reaching of a stop of the nozzle operation. For instance, the sudden increase of braking torque experienced by the servo motor 1305 can be detected, or the very stop of nozzle movement or stop of rotation of an output axis of the motor while driving the servo motor 1305 can be detected.

Furthermore, in order to increase the nozzle movement control, provide means for detecting erroneous conditions, etc, a nozzle tip position detector 1313 is arranged to detect the vertical position of each nozzle tip. The nozzle tip position detector is useful in all embodiments of the mounting head. For instance, in case of component surface portions of different heights these heights can be pre-programmed, thereby increasingly ensure a correct determination of that all nozzles have reached the respective surface portions and have reached the correct surface portion. Additionally, by means of the position detector it is possible to speed up the operation of moving the nozzle(-s) into contact with the component(-s), in that the movement can be diversified to be faster at a far distance from the component, and then slowed down when approaching the component. As a further example, for the embodiment using servo motors and a servo controller, the servo controller can be arranged to align at least two nozzle tips with each other by means of input from the nozzle tip position detector 1313.

Referring now to Fig. 6, another way of synchronizing nozzles is to have a tooltip made for multiple nozzles, this way multiple nozzles will be synchronized via a common tooltip. Thus, for instance two nozzles 601 are combined to one by means of a two-to-one tooltip 603, i.e. a kind of a Y-coupling, which has an output nozzle 605 of a larger diameter than the combined nozzles 601. Consequently, the component 607 is held by a single but larger nozzle 605 than if held by the two combined nozzles 601.

Referring to Fig. 7, for pick and place of oddly shaped parts a grip tool 703 may be required. When using multiple nozzles 701 with servo controlled

synchronization it is possible to use some nozzles to control the gripping mechanism. For example, three aligned nozzles 701 are used with a grip tool 703 having two claws 705 gripping the component 707 from its sides, and being operated by means of raising and lowering the two outer nozzles 701.

As illustrated in Figs. 8a-8d, a sequence performed when picking a component using a grip tool with individually controlled vertical movements of nozzles is as follows:

1. Open tool. The two side nozzles 801 and 803 are moved down relative to the middle nozzle 802, this relative movement will open the claws 805 of the grip tool.

2. Move down. All three nozzles are then synchronously moved down to a level where the component 807 can be gripped.

3. Close tool. Side nozzles 801 and 803 are moved upwards relative to middle nozzle 802, until the component 807 is gripped with the claws 805. To hold the component 807 side nozzles 801 and 803 are continuously forced upwards which gives a grip force onto the sides of the component 807. During this step, the middle nozzle 802 is held still.

4. Move up with component. All three nozzles 801, 802, 803 are synchronously moved upwards. To keep grip force onto the component 807, the side nozzles 801 and 803 are still forced upwards relative to the middle nozzle 802. According to another embodiment of the component mounting head, as shown in Figs. 14 and 15, it is arranged to pick components having an uneven top surface. This means that different nozzles engage with the component at significantly different heights. In correspondence with the above embodiments, and as shown in Fig. 14, the mounting head comprises a rotatable nozzle holder 1405, and a plurality of spring biased nozzles 1411 , held by the nozzle holder 1405. The nozzle holder 1405, in turn, comprises a vertically fixed nozzle selection unit 1407, and a vertically movable nozzle guide 1409.

In a first example, the component 1415 has a first planar lower surface portion

1417, a second higher planar surface portion 1421, and a third sloping surface portion 1419, extending from the lower planar surface portion 1417 to the higher planar surface portion 1421. It is assumed that the length of the component encompasses first, second, and third nozzles 1423, 1425, 1427, which, when positioned in a picking position, are arranged above each one of the surface portions 1417, 1419, and 1421, respectively. In order to pick the component 1415, the first nozzle 1423 and the third nozzle 1427 are released from the nozzle selection unit 1407, thereby entering the active state.

In order for the machine to know that the second nozzle 1425 should not be activated, due to the sloping surface rendering a good grip difficult, there are different solutions. One solution is to use data regarding the shape of the component among package data, which are programmed into the machine anyhow. The user indicates planar surfaces of the package as a part of the package data.

Consequently, when moving the nozzle guide 1409 downwards the second nozzle 1425, being in the inactive state, is retained by the nozzle selection unit 1407, while the first and the third nozzles 1423, 1427, being in the active state, follow the nozzle guide 1409 downwards until they engage with, at different times due to the height difference, the respective plane surface portions 1417, 1421. Then the first and third nozzles 1423, 1425 are locked in relation to the nozzle guide 1409, in order to ensure their height positions relative to each other. Finally, the component 1415 is lifted by moving the nozzle guide 1409 upwards.

In a second example, as shown in Fig. 15, the component 1430 has a stepped surface with a first smaller surface portion 1431, which encompass the first nozzle 1423, and a second larger surface portion 1432, which encompass the second and third nozzles 1425, 1427. When the component 1430 is to be picked all three nozzles 1423, 1425, 1427 are released and the nozzle guide is lowered until all three nozzles have engaged with the top surface of the component 1430. Then the component is lifted and placed as described above.

According to an embodiment of a component mounting machine, as shown in figs. 9-12, the component mounting machine 901 comprises a machine frame 903, a moving gantry system 905, and a fixed elongate component feeding device 907 attached to the machine frame 903. The gantry system 905 is carried by the machine frame 903 on linear guides 909a and 909b on which the gantry system 905 can move in the X direction, i.e. along the length of the component feeding device 907. Thus, the gantry system 903 is movable between a first end, or board reception end, 911 of the machine frame 903, and an opposite second end, or board delivery end, 913 of the machine frame 903. In this embodiment, the gantry movement is realized with a gantry system movement device 915 comprising a ball screw 917, a ball assembly 919, and a motor 921. The gantry movement can be realized using other types of drive mechanisms as well, such as linear motor, rack and pinion, belt drive etc.

Figure 12 shows a detailed view of the gantry system and the component feeding device. In the gantry system 905, there is a camera 1209, and a mounting head 1207, which are movable in the X and Y directions, although they have a fixed relation to each other. Movements in the X/Y directions of the camera 1209 and mounting head 1207 are realized using X and Y beams, 1203 and 1205. The Y beam 1205 is attached to the ceiling of the gantry system 905 and is not movable. Under the Y beam, the X beam 1203 is attached, for example using linear guides. The X beam 1203 can be moved in the Y direction, i.e. along the Y beam 1205, for example by means of a linear motor. On the front side of the X beam 1203, an X wagon 1208 carrying the camera 1209 and the mounting head 1207 is attached, for example by using linear guides. The X wagon can be moved in the X direction, for example by using a linear motor. It is also possible to use ball screws and rotational motors instead of linear guides and linear motors. It should be noted that the movements in X and Y directions can be performed simultaneously, thereby obtaining movement of the mounting head 1207 in any direction of the X-Y plane.

The feeding device 907 holds feeding banks 1221, and makes it possible to load carrier tapes 121 1, containing electronic components 1213, located in component pockets 1215. The carrier tape 121 1 also contains steering holes 1217, which are used to move the carrier tape 121 1, and thus the components 1213 therein, in the Y direction so that they can be picked up by the mounting head 1207. The camera 1209 is looking downwards in the Z direction, perpendicular to the X and Y directions, and is used for locating fiducial marks on PCBs and also for locating objects in the component feeding device, such as fiducial marks 1219 and components 1213. As an example of the operation of the component mounting machine, here follows a description of the operating sequence of the component mounting machine 901 for the case when three gantry system positions, i.e. positions where the gantry system is halted in order to perform component mounting, are needed to reach all portions of the component feeding device 907 in order to be able to pick any one of all components provided thereby. Of course, a similar sequence is applicable for other numbers of stopping positions.

1. The gantry is moved to a leftmost gantry system position la.

2. A PCB 1 107 at a location 4a is received at a board reception position at the board reception end 91 1, from an incoming conveyor 1 102 and transported by means of a board transportation system 1 105 into a working area of the gantry system 905, to a location 4b, using transport belts in the incoming conveyor 1 102 and the internal conveyor of the board transportation system 1 105.

3. The precise location of the PCB within the gantry system 905 is

determined by means of a camera 1209 attached to the X wagon 1208.

4. The location of the first portion 6a of the component feeding device 907, is determined in relation to the gantry system 905, for example by using the camera 1209 attached to the X wagon 1208.

5. The mounting head 1207 transports all components from the first portion 6a of the component feeding device 907 to the PCB 1 107.

6. The gantry system 905 is moved by means of the gantry system

movement device 915 to a second gantry system position lb, in a way that doesn't change the relative position between the PCB 1 107 and the gantry system 905.

7. The location of a second portion 6b of the component feeding device, is determined in relation to the gantry system 905, for example by using the camera 1209 attached to the X wagon 1208.

8. The mounting head 1207 transports all components from the second portion 6b of the component feeding device to the PCB 1 107.

9. The gantry system 905 is moved to a third position lc, in a way that does not change the relative position between the PCB 1 107 and the gantry system 905.

10. The location of a third portion 6c of the component feeding device 907, is determined in relation to the gantry system 905, for example using the camera 1209 attached to the X wagon 1208. 1 1. The mounting head 1207 transports all components from the third portion 6c of the component feeding device 907 to the PCB 1 107.

12. The PCB 1 107 at location 4b within the gantry system 905 is transported by means of the board transportation system 1 105 from the internal conveyor 1105 to an outgoing external conveyor 1 103, at a board delivery position at the board delivery end 913 of the component mounting machine 901, to a location 4c outside of the working area, using transport belts in the internal conveyor and the outgoing conveyor. The moving gantry invention solves the conflicting requirements of the gantry system, i.e. fast, accurate, large feeder capacity and cost-efficient design, by means of making the whole gantry system movable, so that it can move between different parts of the component feeding device. The movement of the whole gantry system does not need to be very accurate, and it does not need to be very fast. This makes the gantry movement mechanism much more cost efficient than the traditional solution which consists of a gantry that is large enough to be able to reach the whole component feeding device.

In steps 4, 7 and 10 of the above-described operating sequence of the component mounting machine, the currently accessible part of the component feeding device 907 needs to be located in relation to the gantry system 905. There are several possibilities for determining this relation:

1. Using the camera 1209 attached to the X wagon 1208 to locate fiducial marks on the feeder bank 1221.

2. Using the camera 1209 attached to the X wagon 1208 to locate fiducial marks 1219 on individual feeders 1223 in the feeder bank 1221. The difference compared to method 1 is that here there is a one to one correspondence between fiducial marks and carrier tapes. In this case, it may also be possible to use the steering holes 1217 as fiducial marks.

3. Using the camera 1209 attached to the X wagon 1208 to locate

component pockets 1215 in the component carrier tape 121 1.

4. Using a mechanical stop mechanism that is accurate enough.

5. Using a linear scale to determine the stopping position of the movable gantry.

6. Rotational position sensor connected to the drive mechanism of the

gantry to determine the stopping position of the movable gantry. The first three methods that use a camera attached to the X wagon have the advantage of low cost, since such a camera is needed anyway to locate fiducial marks on the PCB where the components are to be placed. The first method has the advantage compared to method 2 and 3, that it doesn't require any machine vision recognizable parts on the component feeders or the component reels. This makes the first method preferable if the machine is supposed to handle many different non-standard types of feeders. On the other hand, providing space on the feeder bank for fiducial marks may be inconvenient, in which case methods 2 or 3 would be preferable.

Methods 4, 5 and 6 have an advantage compared to the first three methods, in that after the movable gantry stops, no extra time is needed for image acquisition. On the other hand, methods 4, 5 and 6 require extra hardware compared to the first three methods, so the first three methods may have a cost advantage. Mechanical stop mechanism can have two purposes; determine the exact stop position and/or keeping the position of the gantry fixed. The mechanical stop mechanism can be realized with either of:

1. A moving part with any shape creating an interlock relative to another part when parts are moved together.

2. A movable mechanical part acting as a stop in only one direction, and using the drive mechanism to keep the gantry fixed onto this stop.

3. A friction based stopping mechanism, designed as a traditional brake, and a position sensor to determine the exact position.

The vision centering device (203, fig 2) can be arranged in different ways in relation to the movable gantry:

1. The vision centering device can be firmly attached in the movable gantry module.

2. The vision centering device 1227 can be movable in the X direction

independently from the movable gantry module.

3. The vision centering device is in a fixed position in relation to the feeder bank. In this case, more than one vision centering device is typically needed to obtain good mounting speed.

The internal conveyor (1 105, fig 1 1) can be either a short and movable conveyor, as a part of the movable gantry or a long conveyor fixed in relation to the feeder bank. If the internal conveyor is fixed it must be long enough to be able to fetch incoming PCB:s and leave outgoing PCB:s. The main differences between having a movable or fixed internal conveyor are: 1. A fixed internal conveyor needs to be bigger and it is therefore a less cost effective solution.

2. With a fixed conveyor the PCB needs to be clamped and located several times, which are slow operations, and consequently this will be time consuming.

3. With a fixed conveyor is possible to mount components on a PCB that is longer than the movable gantry.

4. With a fixed conveyor it is possible to utilize a so called Dual Lane

conveyor. A Dual Lane conveyor has two separate lanes to reduce the board change over time.

The basic moving gantry invention can be improved in several ways in order time and therefore increase throughput of the machine. Some examples:

1. A common situation is that when the gantry moves from one stop

position to the next, the mount head will need to exchange one or more mount tools, since different feeder banks will likely contain different component types, which require different mount tools for reliable pick up. In this situation, the changing of the mount tools can be performed at the same time as when the movable gantry is moving to the next stop position.

2. If a fiducial mark or reference mark on the feeder bank needs to be analyzed in order to determine the exact stopping position of the movable gantry, the XY axes of the gantry can be moved at the same time as the movable gantry. The XY axes are moved to positions so that when the movable gantry stops, the camera attached to the mount head is already centered over the fiducial or reference mark. Furthermore, if the camera has an illumination unit (such as a light bulb), that needs to warm up before reaching full light intensity, this illumination unit can be activated before the movable gantry stops.

3. When the last component has been picked from the feeder bank at a certain stopping position, the gantry can immediately start to move towards the next stopping position. At the same time, the mount head will transport the last component(s) to the centering camera, and then place them on the PCB. Thus, time is saved because the movable gantry is moving at the same time as the XYZ axes are moving.

4. If the movable gantry is using methods 4, 5 or 6 above for determining a stopping position of the movable gantry, or some other method that makes it possible to move the movable gantry without a following time consuming step to determine the stopping position, then it is possible to move the movable gantry more times than strictly necessary in order to reach all feeder positions. For example, in figure 1 1 above, the movable gantry can be stopped at 7 different positions instead of the required 3 positions. The advantage is that a small movement can sometimes happen while the machine is busy centering components and/or placing components on the PCB, thereby making the small movement essentially "free", i.e. it doesn't contribute to the time required to finish mounting all components on the PCB. Of course, these small movements need to happen at the right times during the mounting sequence, in order to give the mount head access to the required parts of the feeder bank at the right times. Optimization software is preferably used when computing how and when to insert the small movable gantry movements into the mounting sequence.

As evident from above, generally, the component mounting machine comprises a machine frame; an elongated component feeder area provided by the machine frame; and a board transportation system, arranged to transport a substrate through the component mounting machine from a board reception position to a board delivery position, while halting the substrate at at least one predetermined position within a working area of the component mounting machine where components are mounted on the substrate. The machine further comprises a mounting head, arranged to pick components at said component feeder area, and place components on the substrate, the mounting head being movable along a first axis and along a second axis perpendicular to the first axis; and a gantry system, movably carried by the machine frame and carrying the mounting head, wherein the gantry system is arranged to operate the mounting head for performing the picking and placing of components, including moving the mounting head along said first and second axis. Additionally, the machine comprises a gantry system movement device attached to the machine frame and arranged to move the gantry system between different gantry system positions along a third axis, parallel to said first axis, thereby providing movement of the gantry system along the feeder area; and a gantry system positioning device. A mounting head moving range of said gantry system covers a portion of the component feeder area, wherein the gantry system positions are chosen such that different portions of the feeder area becomes accessible for the mounting head, and wherein a mutual positioning between the gantry system and the substrate is maintained at the different gantry system positions. By making the gantry system shorter than the length of the feeder area, and providing the gantry system movement device it has the large machine advantage of housing a large number of component feeders, while it still has the small machine advantage of a relatively low mass and small size gantry system.

According to an embodiment of the component mounting machine the gantry system positioning device comprises a vision unit.

According to an embodiment of the component mounting machine, the gantry positioning device comprises fiducial marks provided within the feeder area, wherein the vision unit is attached to the mounting head, and wherein the gantry system is arranged to be positioned in the gantry system positions by localizing the fiducial marks by means of the vision unit. The fiducial marks can be arranged at any suitable part within the feeder area, such as on a feeder bank, which is arranged to hold the feeders, or on a feeder.

According to an embodiment of the component mounting machine, the vision unit is attached to the mounting head, components are provided in component pockets of component carrier tapes, which are provided in the feeder area, and the component mounting machine is arranged to locate the component pockets by means of the vision unit.

According to embodiments of the component mounting machine the system positioning device comprises different kinds of means for achieving a stop function, such as a mechanical stop mechanism; a linear scale and a linear scale detector, arranged to determine the gantry system position; or a rotational position sensor connected to the gantry system movement device and arranged to determine the gantry system position.

According to embodiments of the component mounting machine the gantry system comprises a vision centering device, which is attached at a fixed position.

According to embodiments of the component mounting machine it comprises a vision centering device movably attached to the machine frame for movement in parallel with said third axis.

According to embodiments of the component mounting machine the board transportation system comprises a board reception part, which is arranged at the machine frame at a board reception end of the machine, a board delivery part, which is arranged at the machine frame at a board delivery end of the component mounting machine opposite to said board reception end, and

a gantry system part, which is comprised in the gantry system and which is located between said board reception and board delivery ends.

Furthermore, as also evident from above, generally a method of mounting components in a component mounting machine, which comprises a gantry system, comprising a movable mounting head, a board transportation system, and an elongate feeder area where components are provided, wherein a mounting head moving range of the gantry system covers a portion of the feeder area, comprises:

- moving the gantry system to a first gantry system position;

- receiving a substrate at the component mounting machine and transporting the substrate into a component mounting area of the component mounting machine;

- mounting components by moving the mounting head between the feeder area, for picking components, and the substrate, for placing the components thereon;

- repeating at least once:

- moving the gantry system along the length of the feeder area to a next gantry system position where another part of the feeder area is covered by the mounting head moving range; and

- mounting components; and

- transporting the substrate out of the component mounting area.

According to an embodiment of the method, it comprises exchanging, when appropriate due to component differences, at least one mounting tool of the mounting head during said movement of the gantry system to a next gantry system position.

According to an embodiment of the method, it comprises positioning the mounting head in a fiducial mark reading position during the movement of the gantry system to a next gantry system position, and reading, by means of a vision device attached to the mounting head, a fiducial mark provided within the feeder area at said next gantry system position. Preferred embodiments of the devices and methods according to the present invention have been described above. These should be seen as merely non-limiting examples. Many modifications will be possible within the scope of the invention as defined by the claims.

For instance according to an embodiment of the component mounting machine, it comprises more than one mounting head.

Claims

1. A component mounting head arranged to pick up components at a picking position and place the components at a mounting position, the component mounting head comprising a plurality of nozzles, which are vertically movable downwards and upwards for enabling said picking and placing, wherein the component mounting head is arranged to control a plurality of picking operations including at least picking a single component with each nozzle and picking a single component with at least two nozzles in common.

2. A component mounting head according to claim 1 , comprising a vacuum controller connected with the nozzles.

3. A component mounting head according to claim 1 or 2, comprising a nozzle tip impact detector arranged to detect nozzle tip impact against a surface, wherein the nozzle tip is a bottom end of the nozzle.

4. A component mounting head according to claim 3, comprising a nozzle holder, which includes a vertically movable nozzle guide, wherein the nozzle tip impact detector is attached to the nozzle guide and detects nozzle movement relative to the nozzle guide.

5. A component mounting head according to claim 1, 2 or 3, comprising a nozzle holder, which includes a vertically movable nozzle guide, wherein the nozzles are held in one of an inactive position and an active position, wherein a nozzle, when in the active position, is downwardly spring biased against a seat of the nozzle guide.

6. A component mounting head according to claim 5, comprising a locking mechanism for fixing the vertical position of at least one of said nozzles in relation to said nozzle guide.

7. A component mounting head according to claim 1, 2 or 3, comprising an individual vertical movement servo motor for each respective nozzle and a servo controller controlling the servo motors.

8. A component mounting head according to any one of the preceding claims, comprising a nozzle tip position detector, arranged to detect the vertical position of each nozzle tip, wherein the nozzle tip is a bottom end of the nozzle.

9. A component mounting head according to any one of the preceding claims, comprising a nozzle group synchronizer for synchronizing the nozzles of at least one nozzle group, consisting of at least two nozzles, for picking a single component.

10. A component mounting head according to any one of the preceding claims, comprising a component grip tool, which is attached to a plurality of nozzle tips and which is controllable for vertical movement and for grip operation by means of controlling the nozzles which nozzle tips are attached to the component grip tool.

1 1. A component mounting head according to any one of the preceding claims, comprising a nozzle tip interconnector having at least two upper openings connected with a corresponding number of nozzle tips, and a common lower opening having a greater diameter than that of the nozzle tips.

12. A method of controlling nozzles of a mounting head arranged to pick up components at a picking position and place the components at a mounting position, comprising:

- vertically moving the nozzles downwards and upwards for performing said picking and placing, thereby performing one or more of a plurality of picking operations including picking a single component with one nozzle and picking a single component with at least two nozzles in common.

13. A method according to claim 12, comprising:

- rotating the mounting head, after having performed the component picking, and passing a vision centering device during movement to the mounting position.

14. A method according to claim 12 or 13, comprising picking a component having different top surface portions of different heights, by means of several nozzles by controlling the nozzles to engage the different top surface portions.

15. A component mounting machine comprising:

- a component feeder area;

- a board transportation system, arranged to hold a substrate at a substantially fixed position within a working area of the component mounting machine;

- a component mounting head according to any one of claims 1 to 11 ; and - a gantry system, carrying the mounting head and being arranged to move the mounting head for performing the picking and placing of components.

16. A component mounting machine according to claim 15, wherein the mounting head is movable in any direction of a horizontal plane.