Description

The invention relates to a system for mounting electronic components such as integrated circuit components on a substrate such as a printed circuit board.

The system comprises a plurality of component holders each of which is provided to hold at least one electronic component to be mounted on a substrate as well as a revolving device which is provided to revolve the component holders along a pre-determined path, e.g., to rotate the component holders about an axis of rotation, such that each component holder can be brought into a component receiving position for receiving an electronic components and/or into a component mounting position for mounting an electronic component on the substrate, the component receiving position and the component mounting position being arranged on a locus of said pre-determined path. Furthermore, the system comprises an actuator for actuating a component holder in the component receiving position in order to attach an electronic component to the component holder and/or in the component mounting position in order to mount an electronic component on the substrate. Such system is described in WO 2009/066592 A1 . A further component mounting system is known from EP 0 845 934 B1 . The actuator of the known system is provided with a safety device for determining whether a component holder to be actuated is properly placed on the revolving device for actuation by the actuator. This serves to avoid a possible collision between a misaligned component holder and the actuator. For example, a displacement of a component holder can occur when the component holder does not return to its initial position on the revolving device after actuation. However, the dynamics of the actuator while in operation may be impaired by the safety device.

It is an object of the invention to improve the above-described electronic component mounting system by avoiding an impairment of the actuator by the safety device.

According to the invention, the safety device is designed separately from the actuator and is spaced apart from the actuator. By separating the safety device from the actuator, the operation of the actuator is not impaired by the safety device.

In particular, the safety device is spaced apart from the actuator in such a manner that a possible displacement of a component holder can be detected by the safety device before the component holder reaches the actuator during a revolution of the revolving device. To this end, the safety device can be arranged adjacent to the actuator, taking into account the direction of motion of the revolving device.

The component holders can be arranged on the revolving device such that they are movable up and down relative to the revolving device, and the actuator can be designed as an elevating and/or lowering device which elevates or lowers a respective component holder in the component receiving position or the component mounting position. As a result thereof the component holder receives an electronic component and/or places an electronic component on a substrate.

Each component holder is configured such that it is bound to return to its initial position on the revolving device (operative position) after actuation if the system works properly. This can be achieved due to an impact by the actuator and/or by biasing each component holder into its operative position by elastic means such as a spring or by another driving mechanism. For example, the component holder may be returned to its operative position by the actuator and then kept in this position by the elastic means. In case of a component holder that is mounted on the revolving device to be movable up and down with respect to the revolving device the component holder returns to its operative height after actuation.

The safety device may be realized by a position detector to detect a displacement of a component holder from its operative position on the revolving device.

According to one aspect of the invention the safety device comprises a mechanical position detector for mechanically screening the position of a component holder on the revolving device. The mechanical position detector may comprise a movable part, the movable part on the one hand and a respective component holder on the other hand being formed such that a cutout and a corresponding protrusion engage each other if the component holder is properly placed in its operative position on the revolving device. Conversely, if the component holder is displaced with respect to its operative position, this will cause a deflection of the movable part. Thus, a collision between the component holder and the actuator can be avoided by stopping the revolving device.

The movable part of the position detector may be a lever that is swivel-mounted to the position detector. A suitable sensor, such as a photoelectric barrier or a potentiometer, may be used to detect a deflection of the movable part.

According to another aspect of the invention, the position detector is provided in the form of a contactless detector, such as a contactless sensor or a camera. A camera cannot only detect the position of a component holder, but it may also be used to investigate whether an electronic component is attached to a component holder.

The invention will now be explained in further detail with respect to the Drawings. In the Drawings:

Figure 1 A shows a top view of a first embodiment of an electronic component mounting system;

Figure 1 B shows a side view of the electronic component mounting system according to Figure 1 A; Figure 2A shows a top view of a second embodiment of an electronic component mounting system; Figure 2B shows a side view of the electronic component mounting system according to Figure 2A.

According to Figures 1 A and 1 B a system for mounting electronic components C on a substrate (rotating pick and place apparatus) comprises a revolving device 1 which pivots around an axis A, a plurality of component holders 2 (component disposing elements) which are movably mounted on the revolving device 1 , and an actuator 3 for actuating a respective component holder 2 so that an electronic component C attached to the component holder 2 is placed on a substrate such as a printed circuit board. The revolving device 1 has a base portion 10 receiving the component holders 2 and a driving portion 12 for connecting the revolving device 1 to a power unit driving the revolving device 1 such that it performs a rotation R about the axis A.

Each component holder 2 is mounted to the revolving device 1 in such a manner that it is movable with respect to the revolving device in a longitudinal direction, e.g., along the axis of rotation A of revolving device 1 . In other words, according to the embodiment shown in Figures 1 A and 1 B the component holders 2 can be moved up and down with respect to the revolving device 1 . The component holders 2 are distributed on the revolving device 1 along its direction of rotation R and are spaced apart from each other. Each component holder 2 comprises a mounting portion 20 for movably mounting the respective component holder 2 to the revolving device 1 and a holding portion 22 for attaching an electronic component C. Opposite to the holding portion 22, circumferential projections 26, 28 are provided on each component holder 2. These serve to detect a possible displacement of a component holder 2 with respect to its operative position on revolving device 1 ; the operative position being defined as a position in which a respective component holder 2 may be properly actuated by the actuator 3 or, more precisely, by an actuating lever 35 of actuator 3 which is mounted on a base body 30 of actuator 3.

In order to be actuated by actuator 3, a component holder 2 has to be brought into a component mounting location L by a rotation of revolving device 1 (about its axis of rotation A). In its component mounting location L a respective component holder 2 is coupled to the actuator 3 or, more precisely, to its actuating lever 35. Thus, the component holder 2 can be actuated by actuator 3 such that an electronic component C attached to the component holder 2 is placed on a substrate, e.g., a printed circuit board - provided that the component holder 2 is properly placed in its operative position on revolving device 1 . (The electronic component C has to be attached to the component holder 2 at some component receiving location which may be the same as the component mounting location or which may be a separate location.) After placement of the electronic component C, the component holder 2 is returned to its operative position, e.g. by actuator 3. To this end, actuating lever 35 may be provided with an engagement portion, such as a fork-shaped portion, by means of which it engages the component holder 2 in order to move it down or up, respectively.

A system for mounting electronic components on a substrate in form of a rotating pick and place apparatus is known from the prior art, for example from WO 2009/066592 A1 or EP 0 845 934 B1 .

In Figures 1 A and 1 B, the component holders 2 are shown in their respective operative position in which they can be actuated by the actuator 3 through its actuating lever 35, as illustrated in Figure 1 B, after having been brought into the component mounting location L indicated in Figure 1 A. An actuation of a component holder 2 by actuator 3 leads to a movement of the respective component holder 2 downwards along the axis of rotation A. Due to such downward movement the electronic component C attached to a respective component holder 2 can be mounted on a substrate which is located below the component holders 2. Thereafter, the component holder 2 shall return to its initial position/operative position. This can be achieved by an elastic force produced by a spring or by a driving mechanism. It is important to ensure that a respective component holder 2 is indeed positioned in its operative position when it reaches the component mounting location L. A displacement of a component holder 2 with respect to its operative position may not only lead to a malfunction of the system but also to a collision with the actuator 3, potentially damaging its actuating lever 35.

In order to detect a possible displacement of a component holder 2 with respect to its operative position, a safety device 4 is provided adjacent to actuator 3. The safety device 4 is separated from actuator 3 and is spaced apart from actuator 3 along the direction of rotation R of revolving device 1 .

The safety device 4 is a mechanical position detector for mechanically screening the position of a respective component holder 2 before it reaches its component mounting location L during a rotation of revolving device 1 . The safety device 4 comprises a movable part 45 which is movably attached to a base body 40 of safety device 4. According to the embodiment shown in Figures 1 A and 1 B, movable part 45 is formed by a lever which is swivel-mounted to the base body 40 so that it can pivot about an axis 42. In general, movable part 45 can also be movable along a non-circular path. As can be seen from Figure 1 B, movable part 45 comprises cutouts 46, 48 which are engaged by the projections 26, 28 of a component holder 2 which is just about to reach the component mounting location L - if the respective component holder 2 is properly placed in its operative position. On the other hand, if the component holder 2 interacting with the safety device 4 is displaced with respect to its operative position (e.g., along the axis A), then the projections 26, 28 of component holder 2 will not engage the cutouts 46, 48 of movable part 45. This will cause a deflection of movable part 45 relative to base body 40 due to a collision of movable part 45 with the displaced component holder 2. Specifically, in the embodiment shown in Figures 1 A and 1 B, movable part 45 will be rotated about the axis 42 as indicated by an arrow in Figure 1 A. A deflection of movable part 45 may be detected by any suitable sensor 44, such as a light barrier, a potentiometer etc. The deflection of movable part 45 indicates that the component holder 2 currently interacting with movable part 45 is displaced with respect to its operative position. As a consequence, a rotation of revolving device 1 can be stopped in order to avoid a collision between the respective component holder 2 and the actuator 3.

Movable part 45 of safety device 4 may be biased towards its starting position by elastic means, such as a spring, so that it returns to its starting position after an interaction with a displaced component holder 2. As the safety device 4 is physically separated and spaced apart from actuator 3 it does not interfere with the operation of actuator 3 that consists in actuating a component holder 2 located in the component mounting location L.

According to another embodiment of the invention which is shown in Figures 2A and 2B, the safety device 5 is formed by a contactless position detector such as a sensor or a camera. Apart from the design of the safety device, this embodiment is identical to the system shown in Figures 1 A and 1 B. Therefore, reference is made to the description of Figures 1 A and 1 B with respect to the remaining elements of the electronic component mounting system of Figures 2A and 2B. For facility of inspection of the Drawings, only a portion of actuator 3 is displayed in Figures 2A and 2B.

The safety device 5 in form of a contactless detector serves to detect a displacement of a component holder 2 before it reaches the component mounting location L. As in the embodiment of Figures 1 A and 1 B, such displacement will typically occur in the form of a vertical displacement of a component holder 2 along the axis of rotation A, in particular, if a component holder 2 does not return to its operative position after actuation. The contactless position detector may be realized by a sensor such as a photoelectric sensor, a capacitive sensor etc. According to Figure 2B, the safety device 5 in form of a contactless position detector is arranged to detect a possible displacement of a component holder 2 at an end portion 24 of the component holder 2 facing away from its holding portion 22. Alternatively, as also indicated in Figure 2B, a safety device 5' in form of a contactless position detector may be arranged such that it detects a displacement of a component holder 2 at its holding portion 22. If the safety device 5' comprises a camera, it may not only be used to detect a displacement of a component holder 2 but also to check whether an electronic component C is attached to the component holder 2.