WO2007105953A1

WO2007105953A1 - Device for automated laser cutting of a flat carrier provided with encapsulated electronic components

Info

Publication number: WO2007105953A1
Application number: PCT/NL2007/050104
Authority: WO
Inventors: Willem Antonie Hennekes; Hendrik Wensink
Original assignee: Fico B.V.
Priority date: 2006-03-16
Filing date: 2007-03-15
Publication date: 2007-09-20
Also published as: NL2000028C2; TW200800455A

Abstract

The invention relates to a device (20) for cutting with a laser beam of a substantially flat carrier (21) provided with encapsulated electronic components (22) by mutually displacing the laser beam and the carrier (21), comprising: supply means (23), a product holder (26) for holding the carrier, inspection means (25,29,30), a laser source (28) for generating a laser beam, positioning means for positioning the product holder, control means for the product holder and a laser beam, and discharge means (35,36).

Description

Device for automated laser cutting of a flat carrier provided with encapsulated electronic components

Device for cutting with a laser beam of a substantially flat carrier provided with electronic components, for instance encapsulated with epoxy, by mutually displacing the laser beam and the carrier.

Cutting electronic carriers with encapsulated electronic components with a laser beam is a known technique which is inter alia used to release segments from a larger carrier (also designated as a board or lead frame). Laser beam cutting is applied as an alternative to the more traditional machining processing techniques such as punching, sawing and milling. Separating segments from the carrier with a laser offers a number of important advantages, such as a great freedom of form regarding the segments for releasing and being able to carry out the separating operation dry or wet as desired, which can be particularly important, for instance for liquid-sensitive electronic components which can be situated on the carrier segments for releasing. Another advantage of laser cutting is that it generates a relatively small amount of waste compared to more traditional separating, inter alia because of the relatively small width of the cut to be made. An associated advantage is that the carrier material can be utilized efficiently. There is an increasing demand for electronic components which are shielded by a metallized cover element mounted on the carrier. The metallized cover element can be manufactured entirely from metal but it is also possible that it is a cover element of laminar construction with at least one metal layer. Metallized cover elements are extremely suitable for being separated by means of laser cutting, they can be provided with one or more openings for improved heat exchange and/or pressure levelling with the environment. A consideration here is controlling the drawbacks of the occurrence of contamination as a result of inter alia the evaporation of material (for instance metals, whether or not fully combusted hydrocarbons originating from substrate, glue, epoxy and so on) and subsequent deposition of this material. There is further a trend for the use of increasingly smaller encapsulated electronic components, which are placed on the carrier with a high density. As will be apparent from the foregoing, laser cutting of a flat carrier provided with encapsulated electronic components is a complex and sensitive process which comprises a plurality of operations and which must be carried out extremely accurately. The present invention therefore has for its object to provide a device for automated, efficient and effective laser cutting of a flat carrier provided with encapsulated electronic components.

For this purpose the present invention provides a device for cutting with a laser beam of a substantially flat carrier provided with encapsulated electronic components by mutual displacement of the laser beam and the carrier, comprising: supply means for displacing the carrier with encapsulated electronic components from a supply location to a product holder, a product holder for holding the carrier with encapsulated electronic components, inspection means for detecting the supplied carrier with encapsulated electronic components, a laser source for generating a laser beam, positioning means for mutually positioning the laser beam and the product holder, control means for mutually displacing the product holder and a laser beam to be generated by the laser source in controlled manner, and discharge means for displacing the carrier with encapsulated electronic components, divided into segments by laser cutting, from the product holder to a discharge location. With such a complete laser cutting device encapsulated electronic components can be cut in fully automatic and accurate manner.

It is very advantageous if the laser source is provided with a galvo head whereby at least part of the mutual displacement of the laser beam and the carrier with encapsulated electronic components is controlled. The laser beam can be moved quickly and accurately with a galvo head, the alternative is to displace the loaded product holder, which is less desirable, if only because of the mass inertia thereof. Applying a galvo head will be beneficial to both the cutting quality and the cutting speed.

Since the carriers are mostly supplied in cassettes it is desirable that such cassettes can also be unloaded automatically. For this purpose the supply means preferably comprise an automatic feeder which is adapted to remove the carrier from a supply holder. On the other hand, the device according to the invention can also be aligned such that the carriers are automatically offered in succession to the cutting device by a transport system. For this purpose the supply means can comprise a supply path for supplying the carrier. The supplied carriers must then be placed on a product holder. For also automating this step it is desired that the supply means comprise a manipulator for placing the carrier with encapsulated electronic components on the product holder. Such a manipulator can consist of a simple gripper head with only a few degrees of freedom, although manipulators can be envisaged with many more options for use, such as for instance a robot arm.

In order to monitor the presence, positioning and/or quality of the supplied carriers a preferred variant provides inspection means which comprise a first camera for the visual detection respectively monitoring of the supplied carrier. The mutual positioning of the carrier and the product holder can herein in particular also be the subject of detection and/or inspection. By accurately determining this mutual positioning, cutting can then take place with great accuracy and with an accurate position control of the product holder. It is therein of course desired that the detected images are utilized as input for the process control in the laser cutting (feed- forward). The inspection means can in addition (or instead of the first camera) also comprise a second camera for detecting at least one reference mark on both flat sides of the carrier in order to thus determine a reference value for an individual carrier. With such a second camera the accuracy respectively another quantitative or qualitative quantity of the supplied carriers can be determined; once again with the advantageous possibility of improving the process control in the laser cutting on the basis of these detections to acquire an even higher quality of cutting. The second camera can take a double form, i.e. be arranged on either side of the carrier, but it is of course more advantageous if only a single camera suffices. This is possible if the second camera connects to at least one mirror in order to thus be able to observe two sides of the carrier with a single detection.

To fix the position of the carrier relative to the holder means it is advantageous if the positioning means are provided with vacuum means for fixing the carrier relative to the product holder with underpressure. After registering the mutual positioning of carrier and product holder, a compensation can take place in the control of the laser cutting (in particular by actuation of the galvo head) for the extent to which the mutual positioning deviates from the standard or normal mutual positioning. It is then however important that, once the mutual positioning of the carrier and the product holder is registered, it does not change any more. The mutual positioning of carrier and product holder can now be guaranteed in advantageous manner by the proposed vacuum means. For detecting the position accuracy of the product holder relative to the laser source the positioning means can be provided with specific detection means, for instance third camera means. An extra detection of the actual situation will result once more in a further increase of the accuracy with which the laser cutting process can be carried out. Deviations in the actual position of the product holder relative to the laser source relative to the prognosticated position can also be compensated by means of intelligent actuation of the laser cutting process. As will be apparent from the foregoing, it is desired that the device is provided with an intelligent control for processing registered measurement values and converting them into control signals which influence the device.

In yet another preferred embodiment the discharge means comprise a double manipulator whereby the severed encapsulated electronic components and any remaining plate material can be gripped separately. With such a double manipulator the severed encapsulated electronic components and the remaining plate material (scrap) can be separated from each other in that they can be laid off independently from each other. It is therein desired that the discharge means comprise a discharge position controlled by the discharge means for remaining plate material and that the discharge means comprise a discharge position controlled by the discharge means for severed encapsulated electronic components.

In yet another preferred embodiment the device is provided with cleaning means for cleaning severed encapsulated electronic components. It is herein possible to envisage mechanical cleaning means such as for instance optionally movable brushes, ultrasonic cleaning in a liquid or gas, irradiation, contaminant-absorbing material or another cleaning technique as known from the prior art. Regarding the movable brushes it is noted that they can make a relative movement relative to the products for cleaning. It will be apparent that this can be realized by displacing the brush, displacing the products for cleaning or by displacing both simultaneously. The displacement can for instance be achieved by a rotating brush, an intermittent brush, a movement composed of a plurality of movements and so on.

Yet another possibility provides the shielding of the electronic components for laser cutting, for which purpose the device can for instance be provided with supply means for foil material and discharge means for foil material. Yet another possibility is to provide the device with displaceable and reusable shielding elements in the form of masks and/or three-dimensional shielding elements.

Yet another embodiment variant of the device is provided with conditioning means for creating a conditioned environment between the laser source and the positioning means. Herein can for instance be included the realization of underpressure or overpressure. Another possibility is the supply of a specific gas (mixture) and/or the supply of liquid. The laser cutting can therein be carried out under a liquid layer (for instance a liquid film) but the liquid can also be supplied in the form of a vapour or mist.

The discharge means preferably also comprise inspection means for detecting the action of the discharge means. It is for instance possible to monitor whether a discharge gripper with a double form correctly and completely discharges the products and the waste material to the correct locations. It can possibly also be envisaged that a process monitoring of the laser cutting is carried out by means of these inspection means arranged behind the laser beam. It is herein for instance possible to envisage the detection of the realized cutting patterns, the accuracy thereof and the degree to which contamination of the products has occurred during cutting.

Further improvement of the cutting quality and/or the cutting speed can also be acquired by suction means or blowing means arranged near the laser source for discharging contamination released during the laser cutting. Using such suction means (part of) the material released in the laser cutting can be exhausted immediately.

The present invention will be further elucidated on the basis of the non- limitative exemplary embodiments shown in the following figures. Herein: figure 1 shows a perspective view of a fully automatic laser cutting device according to the present invention, figure 2 shows a schematic top view of a fully automatic laser cutting device according to the present invention, figure 3 shows a schematic top view of an alternative embodiment variant of a fully automatic laser cutting device according to the present invention, and figure 4 shows a perspective view of cleaning means as can optionally form part of an embodiment variant of the laser cutting device according to the present invention.

Figure 1 shows a perspective view of a fully automatic laser cutting device 1 with supply means 2 for unloading cassettes, not shown in this figure, with carriers with encapsulated electronic components for laser cutting. The carriers placed on a conveyor belt 4 by supply means 2 are inspected by means of a camera 3. A manipulator 5 grasps the carriers supplied on conveyor belt 4 in succession and places them on a product holder 6. The position of the carrier on product holder 6 is then inspected by a second camera 7, after which product holder 6 is moved to below a combined laser source/galvo head 8. The galvo head consists of an assembly of displaceable mirrors and lenses whereby the laser beam generated by the laser source can be accurately controlled. Behind laser source/galvo head 8 is arranged a cleaning unit 9 for cleaning the severed encapsulated products. By means of double transfer means 10 the severed products and the remainder of the carrier are gripped and laid off in respectively a transfer unit 11 and a discharge opening 12, to which a waste container or rubbish bin, not shown in this figure, can for instance connect. In transfer unit 11 the severed products are placed on a tray 13 which is then slid into a holder 14. Fully automatic laser cutting device 1 is operated by means of a screen 15 which, like light signal generator 16, is also used for the output of data.

Figure 2 shows a top view of a fully automatic laser cutting device 20 in which the separate functions are shown schematically. A carrier 21 with encapsulated electronic components 22 is supplied by a supply unit 23, on the front side of which are placed operating means 24 of the whole device 20. Carrier 21 with encapsulated electronic components 22 is displaced toward a camera 25 according to arrow Pi for then being carried through according to arrow P₂ after inspection to a product holder 26 which can be displaced in the plane of the carrier in X and Y direction, as indicated by arrow cross 27, to thus position carriers 21 with encapsulated electronic components 22 below a laser head 28. Before the laser cutting takes place a second camera 29 however accurately registers the placement of carrier 21 with encapsulated electronic components 22 on product holder 26. After the laser cutting operation is carried out the cutting result is inspected by a third camera 30. Severed electronic components 31 are cleaned 32, rotated (Ri) and placed at an intermediate station 33. After a renewed transfer the severed electronic components 31 are placed on a tray 35 in a desired orientation, which usually deviates from the orientation in which electronic components 22 were situated when they still formed part of carrier 21. Finally, trays 35 are slid into a tray holder 36. Any rejected products can be placed on a waste tray 37 or be dumped in a waste container 38.

Figure 3 shows a top view of a fully automatic laser cutting device 50, the components of which corresponding to the components of fully automatic laser cutting device 20 as shown in figure 2 are designated by the same reference numerals. Other than fully automatic laser cutting device 20 shown in figure 2, laser cutting device 50 is provided with a feed path 51 whereby carrier 21 with encapsulated electronic components 22 is supplied. According to the previous figure, carrier 21 with encapsulated electronic components 22 is here also displaced according to arrow Pi toward a camera 25 for then being carried through according to arrow P₂ after inspection to a product holder 26. At the position of laser head 28 are arranged supply means 52 and discharge means 53 for a screening material 54. In the shown embodiment variant they are a supply 52 and a discharge 53 for foil material 54, although screening material other than foil 54 can also be envisaged. Supply means 52 and discharge means 53 can thus also consist of a manipulator whereby a mask or a (optionally reusable) screening with a different form can be placed between laser head 28 and carrier 21. After the cutting result is inspected by a third camera 30 the assembly of carrier with severed components is placed in a cleaning unit 55 which can be provided with a rotatable brush 56 and/or any other cleaning means. The cleaning unit can also be provided with a wet cleaning module (for instance in the form of an immersion bath) which can have an ultrasonic action. After cleaning a renewed monitoring of the results achieved up to that moment can take place by means of a fourth camera 57. The detection by means of fourth camera 57 can be the input for the further processing (in particular the selection) which can be carried out subsequently. Regarding the further discharge reference is made to the description associated with figure 2. The lay-out shown in this figure can of course be extended as desired with extra modules which provide additional functionality.

Finally, figure 4 shows a perspective view of cleaning means 40 whereby severed electronic components can be cleaned. Cleaning means 40 are here drawn upside down to simplify understanding thereof. Cleaning means 40 comprise a rotatable brush 41 which is driven by an electromotor 42 with interposing of a belt 43. Brush 41 is surrounded by a suction mouth 44 whereby air is sucked in. For this purpose suction mouth 44 is connected to a discharge channel 45.

Claims

1. Device for cutting with a laser beam of a substantially flat carrier provided with encapsulated electronic components by mutually displacing the laser beam and the carrier, comprising:

- supply means for displacing the carrier with encapsulated electronic components from a supply location to a product holder,

- a product holder for holding the carrier with encapsulated electronic components,

- inspection means for detecting the supplied carrier with encapsulated electronic components,

- a laser source for generating a laser beam,

- positioning means for mutually positioning the laser beam and the product holder,

- control means for mutually displacing the product holder and a laser beam to be generated by the laser source in controlled manner, and - discharge means for displacing the carrier with encapsulated electronic components, divided into segments by laser cutting, from the product holder to a discharge location.

2. Device as claimed in claim 1, characterized in that the laser source is provided with a galvo head whereby at least part of the mutual displacement of the laser beam and the carrier with encapsulated electronic components is controlled.

3. Device as claimed in claim 1 or 2, characterized in that the inspection means comprise a first camera for detecting the supplied carrier.

4. Device as claimed in any of the foregoing claims, characterized in that the inspection means comprise a second camera for detecting at least one reference mark on both flat sides of the carrier in order to thus determine a reference value for an individual carrier.

5. Device as claimed in claim 4, characterized in that the second camera connects to at least one mirror in order to thus be able to observe two sides of the carrier with a single detection.

6. Device as claimed in any of the foregoing claims, characterized in that the supply means comprise a supply path for supplying the carrier.

7. Device as claimed in any of the foregoing claims, characterized in that the supply means comprise an automatic feeder which is adapted to remove the carrier from a supply holder.

8. Device as claimed in any of the foregoing claims, characterized in that the supply means comprise a manipulator for placing the carrier with encapsulated electronic components on the product holder.

9. Device as claimed in any of the foregoing claims, characterized in that positioning means are provided with vacuum means for fixing the carrier relative to the product holder with underpressure.

10. Device as claimed in any of the foregoing claims, characterized in that the positioning means are provided with third camera means for detecting the position accuracy of the product holder relative to the laser source.

11. Device as claimed in any of the foregoing claims, characterized in that the device is provided with an intelligent control for processing registered measurement values and converting them into control signals which influence the device.

12. Device as claimed in any of the foregoing claims, characterized in that the discharge means comprise a double manipulator whereby the severed encapsulated electronic components and any remaining plate material can be gripped separately.

13. Device as claimed in any of the foregoing claims, characterized in that the discharge means comprise a discharge position controlled by the discharge means for remaining plate material.

14. Device as claimed in any of the foregoing claims, characterized in that the discharge means comprise a discharge position controlled by the discharge means for severed encapsulated electronic components.

15. Device as claimed in any of the foregoing claims, characterized in that the inspection means for detecting the supplied carrier with encapsulated electronic components are adapted to monitor the quality of the supplied carrier with encapsulated electronic components.

16. Device as claimed in any of the foregoing claims, characterized in that the device is provided with cleaning means for cleaning severed encapsulated electronic components.

17. Device as claimed in claim 16, characterized in that the cleaning means comprise a brush which can be displaced relative to the encapsulated electronic components divided into segments by laser cutting.

18. Device as claimed in claim 16 or 17, characterized in that the cleaning means possess a contaminant-binding contact surface.

19. Device as claimed in any of the claims 16 - 18, characterized in that the cleaning means comprise an exhaust.

20. Device as claimed in any of the foregoing claims, characterized in that the device comprises inspection means for detecting the encapsulated electronic components divided into segments.

21. Device as claimed in any of the foregoing claims, characterized in that the device is provided with conditioning means for creating a conditioned environment between the laser source and the positioning means.

22. Device as claimed in any of the foregoing claims, characterized in that the discharge means comprise inspection means for detecting the action of the discharge means.

23. Device as claimed in any of the foregoing claims, characterized in that the device is provided with suction means arranged near the laser source for discharging contamination released during the laser cutting.