WO1997048530A1

WO1997048530A1 - Transfer device and arrangement of transfer device and heater

Info

Publication number: WO1997048530A1
Application number: PCT/NL1997/000327
Authority: WO
Inventors: Wilhelmus Hendrikus Johannes Harmsen; Albertus Franciscus Gerardus Van Driel
Original assignee: Fico B.V.
Priority date: 1996-06-17
Filing date: 1997-06-10
Publication date: 1997-12-24
Also published as: NL1003357C2; AU3107997A

Abstract

The invention relates to a device (1) for transferring electronic components mounted on a carrier from a feed position to at least two lay-off positions (7). For this purpose the device comprises a manipulator (6) which is movable between a position close to the feed position and positions close to the lay-off positions, wherein the manipulator is provided with positioning means (43) and the feed position and lay-off positions are provided with counter-positioning means (47) for precise positioning of the manipulator close to the feed position and lay-off positions. These positioning means and counter-positioning means can preferably be formed by at least one protrusion and a recess which co-acts with the protrusion and in which the protrusion can be received in close-fitting manner.

Description

TRANSFER DEVICE AND ARRANGEMENT OF TRANSFER DEVICE AND

HEATER

The invention relates to a device for transferring electronic components mounted on a carrier from a feed position to at least two lay-off positions.

Such a transfer device is applied for instance in a so-called pre-heating device, in which the electronic components for encapsulating which are mounted on a lead frame are preheated before being fed to an encapsulating device. The existing transfer devices of the type de¬ scribed in the preamble have a limited capacity in that they have two lay-off positions available, which lay-off positions are displaceable such that they can be placed one by one in line with the feed position. By means of a linear pusher a lead frame can subsequently then be moved from the feed position to a lay-off position. The dis- placement of the lay-off position generally takes place in that they are arranged on a rotatable table.

The object of the present invention is to provide an improved transfer device with a larger capacity, which also creates the possibility of varying the lay-off position subject to the lead frame for transferring. Another object of the present invention is that the device according to the invention must be relatively inexpensive in terms of production and costs of use.

The invention provides for this purpose a device as described in claim 1. The manipulator preferably compris¬ es engaging means for engaging the carrier, which engag¬ ing means have uncontrolled freedom of movement to a limited degree relative to the frame. An advantage of such a transfer device is that the manipulator can co-act as required with a number of lay-off positions. A very significant cost advantage is realized in that the manip¬ ulator is allowed to make a relatively slightly con¬ trolled movement between the feed position and the lay- off positions. The manipulator can hereby be embodied relatively inexpensively, since the cost of a manipulator depends to a significant extent on the positional accura¬ cy with which the manipulator has to function. Using the transfer device according to the invention a lead frame can nevertheless be engaged respectively laid off accu¬ rately because close to the feed position and the lay-off positions the accurate positioning of a manipulator is realized by the positioning means and counter-positioning means. Another advantage relative to existing transfer devices is that lead frames rotated through 180° can also be- transferred and can be placed once again in the cor¬ rect orientation during transferring. Finally, checking of lead frames is also more reliable, because this check- ing takes place at a distance from the lay-off position instead of above the lay-off position, which is usually heated.

The engaging means of the transfer device can be formed by a mechanical gripper or by a gripper with at least one suction nozzle. A very advantageous embodiment of the positioning means and counter-positioning means is formed by at least one protrusion and a recess which co- acts with the protrusion and in which the protrusion can be received in close-fitting manner. The protrusion can be fixed to the engaging means as well as to the feed position and lay-off positions. It will be apparent that arranging of a protrusion and recesses co-acting there¬ with is relatively very inexpensive when compared to the costs of manufacturing a manipulator with comparable positional accuracy. For good operation the protrusion and/or recess is provided with a chamfered positioning edge.

In another embodiment the longitudinal axes of the lay-off positions are placed at an angle relative to the longitudinal axis of the feed position, so that during displacement from the feed position to a lay-off position the carrier is both translated and rotated. Using such a manipulator linearly fed lead frames can be placed in a configuration corresponding with the configuration for further processing of the lead frames during an encapsu¬ lating process.

The feed position is preferably formed by a feed conveyor, which feed conveyor is preferably provided with at least one buffer position prior to the feed position. More preferably the number of buffer positions is at least equal to the number of lay-off positions minus one. The buffer positions enable successive processing of a batch of lead frames of the same number as that of the lay-off positions, wherein the lead frames are placed at the lay-off positions in the configuration for further processing without there being any danger of the supply of lead frames stopping temporarily before a whole batch of lead frames is processed. Such a device therefore guarantees that, at the start of the processing of a batch, at least sufficient lead frames are present to complete one full configuration of lead frames for fur¬ ther processing. The manipulator is preferably a mechanized arm having at least three degrees of freedom. The manipulator preferably also comprises a gripper rotatable round an axis perpendicular to the plane through the feed posi¬ tion. Such manipulators are also known as "robot arm". The manipulator is preferably provided with at least one detector for detecting a carrier located beneath the manipulator. The detector will detect an incorrect and/or incorrectly positioned lead frame, whereby the further processing of the lead frame is adapted to the observed deviation. It is thus possible for instance to arrange a separate lay-off position for removing incorrect/incor¬ rectly positioned lead frames. This will be further elucidated with reference to the following figure de¬ scription. Finally, at least one lay-off position is preferably provided with heating means for heating a carrier on which an electronic component is fixed. Such a transfer device can be used as pre-heating for carriers before they are supplied to an encapsulating device. During processing in the encapsulating device of the carrier with the electronic components situated thereon it will be possible to limit the difference in temperature be- tween the carrier with the components situated thereon and the encapsulating material, which has a positive effect on the results of the encapsulating process. Such a pre-heating device for carriers can take a compact form, functions with high reliability and can be manufac- tured and used relatively cheaply.

The present invention will be further elucidated with reference to the non-limitative embodiment shown in the following figures. Herein:

Fig. 1 shows a perspective view of a transfer device according to the invention,

Fig. 2 shows a partly cut-away perspective view of the manipulator of the transfer device shown in fig. 1, Fig. 3 shows a perspective view of a detail of the manipulator shown in fig. 2, Fig. 4 shows a perspective view of a mechanical gripper mounted on the manipulator shown in fig. 2, and

Fig. 5 shows a perspective view of two lay-off positions provided with heating means according to the invention. Fig. 1 shows a transfer device 1 comprising a frame 2. Connected to the frame 2 is a conveyor 3 sub-divided into a plurality of parts with which lead frames 4 are carried to a feed position situated under a gripper 5 which forms part of a manipulator 6. A lead frame 4 which is engaged by gripper 5 is then displaced by operating manipulator 6 such that it can be laid off at one of the, in this figure, four lay-off positions 7, which lay-off positions 7 are rigidly connected to frame 2. The lay-off positions 7 in the transfer device 1 shown in this figure are provided with heating elements, as will be elucidated with reference to fig. 5, whereby transfer device 1 can pre-heat lead frames 4 before they are supplied to an encapsulating device. The feed conveyor 3 comprises two buffer positions for lead frames which are situated prior to the feed position above which gripper 5 is situated. These two buffer positions, the feed position and the position in gripper 5 can be monitored for the presence of a lead frame 4. The advantage hereof is that it is possible to then transfer lead frames 4 from feed conveyor 3 to lay¬ off positions 7 only when three lead frames 4 are located on feed conveyor 3 and one lead frame 4 in gripper 5, so that it is certain that all lay-off positions 7 can be filled with lead frames 4. In the case of the heated lay¬ off positions 7 this prevents lead frames 4 having to remain on heated lay-off positions 7 for an unnecessarily long time when the supply of lead frames 4 stops tempo- rarily. In the case of only two lay-off positions 7 it is sufficient when only one lead frame 4 is located in gripper 5 and one at the feed position; this is suffi¬ cient to enable filling of lay-off positions 7.

The lead frames 4 supplied by feed conveyor 3 are first engaged by means of transporting wheels 51 in co- action with pressing wheels 8. Present close to pressing wheels 8 is a sensor (not shown in this figure) for registering the presence of a lead frame 4. The position close to pressing wheels 8 forms the first buffer posi- tion. As lead frame 4 progresses further it is carried to a second buffer position by an endless buffer belt 9. Transporting wheels 51, pressing wheels 8 and buffer belt 9 are actuated by means of diverse sensors 10 which also register whether the buffer positions are filled. Placed in line with buffer belt 9 is a conveyor belt 11 onto which a lead frame 4 can be placed by buffer belt 9. A lead frame 4 lying on conveyor belt 11 can subsequently proceed to the feed position situated under the gripper 5. By operating gripper 5 the lead frame will then be engaged at the feed position and subsequently lifted and displaced to a free lay-off position 7. For a description of the operation of gripper 5 and manipulator 6 reference is made to the following figures. Incorporated in frame 2 is a linear guide 12 along which the manipulator 6 is displaceable in lateral direction (X-direction) . The drive of the lateral movement is performed with a linear motor. Fig. 2 shows manipulator 6 of fig. 1 in partly cut¬ away view. A portion of linear guide 12 is also shown with interposing of which the manipulator 6 is connected to frame 2 of transfer device 1. Manipulator 6 is coupled to frame 2 by means of guide elements 13 which are con- nected to an upper plate 14 of manipulator 6 with inter¬ posing of the guide 12. The mounting of guide 12 provides manipulator 6 with a freedom of movement in lateral direction (X-direction) . Arranged on the underside of plate 14 is a guide rail 15 whereby manipulator 6 ac- quires a degree of freedom in the Y-direction, i.e. in a direction perpendicular to the linear guide 12 (the X- direction) . Carriages 16 arranged around guide rail 15 are displaceable by driving a belt 17 with a motor 18. On the endless belt 17 engages a clamping element 19 which is rigidly connected to carriages 16 with interposing of a plate 20. On the underside of plate 20 a third plate 23 is arranged on a bearing mounted shaft 22. This latter is driven by means of an endless rotation belt 24 and a motor 25 whereby the third plate 23 can be placed in a position as desired. Placed on the underside of the third plate 23 are vertical guide shafts 21 along which a block 26 is displaceable in a vertical direction (Z-direction) . The drive for the vertical movement of block 26 takes place by means of an air cylinder 27, the operation of which will be elucidated with reference to the descrip¬ tion of fig. 3. Arranged on the underside of block 26 is a mounting plate 28 to which gripper 5 can be coupled. On mounting plate 28 is arranged a rotation cylinder 29 for driving gripper 5. Fig. 3 shows a detail of manipulator 6 and in par¬ ticular of the guiding and driving in vertical direction (Z-direction) . The block 26 is displaceable along guide shafts 21, only one of which is shown in this figure. Guide shafts 21 are rigidly connected to the third plate 23. A rotation cylinder 27 with a crank 32 is mounted on block 26. A rod 30 is arranged between crank 32 and block 23. By feeding and discharging air respectively to and from cylinder 27 through the valves 31 the crank 32 rotates whereby block 26 is pulled upward or downward on rod 30.

Arranged in the bearing-mounted shaft 22 is an air channel 35 for passage of actuating air to for instance the rotation cylinder 29 arranged on mounting plate 28. The air channel 35 is provided with a slot-like opening 36 to allow the opening 50 in block 26 to be connected to air channel 35 irrespective of the position of block 26 relative to the central shaft 34. Further arranged on the cylinder 27 are sensors 37 with which the height position of block 26 can be detected.

Fig. 4 shows the gripper 5 for engaging a lead frame 4 fixed to the underside of mounting plate 28. The grip¬ per 5 comprises two rows of gripper elements 38 which are connected to two parallel beams 39. The beams 39 are coupled by means of rods 40 to rotatable elements 41. These latter are displaceable by operating the rotation cylinder 29 shown in fig. 2 which engages on the two protruding operating pins 42 of gripper 5. By rotating the rotatable elements 41 the gripper 5 will engage a lead frame 4 such that the central axis of lead frame 4 is situated in the middle of gripper 5.

The gripper 5 is further provided with positioning pins 43 for precise control of the position in which the gripper is situated at the moment that positioning pins

43 co-act with positioning apertures close to the feed position and lay-off positions. Because the positioning pins 43 ensure accurate positioning of gripper 5 at the moment of engaging and releasing of lead frames by grip- per 5, the manipulator 6 can be embodied relatively inexpensively since the positional accuracy with which manipulator 6 has to function is relatively limited. Because the gripper 5 must have sufficient freedom of movement during positioning in order to assume a position as defined by positioning pins 43, the plate 28 is mounted movably to block 26 by means of a bush 44 having considerable play (see figure 3 herefor) . In figure 2 can be seen that guide pins 21 are narrowed on the underside and drop into plate 28. When block 26 moves upward the play of block 28 round the guide shafts is eliminated. This has the advantage that gripper 5 does not receive any shocks during the rapid movement whereby lead frame 4 could be damaged.

Also placed in gripper 5 is a pin 46 which co-acts with a recess present in lead frame 4.

When an incorrect lead frame 4 is supplied (which is determined on feed conveyor 3) there are three possibili¬ ties: carriers 4 rotated through 180° can be picked up and still laid off in correct orientation; if such a carrier 4 is not suitable for laying off but can still be engaged it can be set down at a position specifically intended for this purpose instead of being laid off at a lay-off position 7. Reference is herein made to fig. 1 where any incorrect or wrongly positioned lead frames 4 can be set down for instance to the left of the lay-off positions 7. A final possibility is that the carrier 4 cannot be picked up and that an operator must remove it from the feed position.

It is very important that at both the feed position and the lay-off positions 7 positioning openings 47 are arranged for co-action with positioning pins 43 of grip- per 5. The positioning openings 47 must be able to re¬ ceive positioning pins 43 in close-fitting manner since possible play between positioning pin 43 and positioning openings 47 immediately introduces positioning inaccura¬ cies. In fig. 5 can also be seen that the lay-off posi- tions 7 are arranged on a platform 48 in which heating elements 49 are arranged. Lead frames 4 can be pre-heated by heating lay-off positions 7, which can be advantageous for further processing of lead frame 4.

Claims

1. Device for transferring electronic components mounted on a carrier from a feed position to at least two lay-off positions, comprising:

- a frame coupled to the feed position and the lay- off positions,

- a manipulator connected to the frame and movable between a position close to the feed position and posi¬ tions close to the lay-off positions, wherein the manipu¬ lator is provided with positioning means and the feed position and lay-off positions are provided with counter- positioning means for precise positioning of the manipu¬ lator close to the feed position and lay-off positions.

2. Transfer device as claimed in claim 1, wherein the manipulator comprises engaging means for engaging the carrier, which engaging means have uncontrolled freedom of movement to a limited degree relative to the frame.

3. Transfer device as claimed in claim 1 or 2, wherein the engaging means are formed by a mechanical gripper.

4. Transfer device as claimed in claim 1 or 2, wherein the engaging means are formed by a gripper with at least one suction nozzle.

5. Transfer device as claimed in any of the forego¬ ing claims, wherein the positioning means and counter- positioning means are formed by at least one protrusion and a recess which co-acts with the protrusion and in which the protrusion can be received in close-fitting manner.

6. Transfer device as claimed in claim 5, wherein the protrusion and/or recess is provided with a chamfered positioning edge.

7. Transfer device as claimed in any of the forego¬ ing claims, wherein the longitudinal axes of the lay-off positions are placed at an angle relative to the longitu- dinal axis of the feed position, so that during displace¬ ment from the feed position to a lay-off position the carrier is both translated and rotated.

8. Transfer device as claimed in any of the forego- ing claims, wherein the feed position is formed by a feed conveyor, which feed conveyor is provided with at least one buffer position prior to the feed position.

9. Transfer device as claimed in claim 8, wherein the number of buffer positions is at least equal to the number of lay-off positions minus one.

10. Transfer device as claimed in any of the forego¬ ing claims, wherein the manipulator is a mechanized arm having at least three degrees of freedom.

11. Transfer device as claimed in any of the claims 2-10, wherein the manipulator comprises a gripper rotat¬ able round an axis perpendicular to the plane through the feed position.

12. Device as claimed in any of the foregoing claims, wherein the manipulator is provided with at least one detector for detecting a carrier located beneath the manipulator.

13. Transfer device as claimed in any of the forego¬ ing claims, wherein at least one lay-off position is provided with heating means for heating a carrier on which an electronic component is fixed.

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