WO2005072041A1

WO2005072041A1 - Encapsulating device with displaceable table, and method of encapsulation

Info

Publication number: WO2005072041A1
Application number: PCT/NL2005/000044
Authority: WO
Inventors: Johannes Lambertus Martinus Dannenberg; Arthur Theodorus Johannes Reijmer; Eustachius Petrus Willibrordus Savenije
Original assignee: Fico B.V.
Priority date: 2004-01-22
Filing date: 2005-01-21
Publication date: 2005-08-04
Also published as: NL1025302C2

Abstract

The invention relates to an encapsulating device for encapsulating electronic components mounted on a carrier, comprising: a frame, two mutually displaceable mould parts connected to the frame, drive means for mutually displacing the mould parts, and feed means for encapsulant connecting to at least one of the mould parts. The invention also relates to a method for encapsulating electronic components mounted on a carrier.

Description

Encapsulating device with displaceable table, and method of encapsulation

The encapsulation of electronic components mounted on a carrier is applied on a large scale. Use is generally made here of moulds consisting of two or more mould parts. A carrier with electronic components for encapsulating is usually placed between the mould parts which are then closed such that they define one or more mould cavities. Liquid encapsulant (epoxy) is subsequently fed under pressure into the mould cavities, for instance using a transfer mechanism wherein plungers exert pressure on pellets ,of encapsulant. The drawback of existing encapsulating devices is that they are expensive and that the encapsulation of electronic components has a relatively long cycle time, whereby the capacity of an encapsulating device is limited.

The object of the present invention is to simplify the existing encapsulating devices and to increase the capacity of encapsulating devices.

This object is realized by means of an encapsulating device of the type stated in the preamble, wherein one of the mould parts comprises a displaceable table. The displaceable table is preferably rotatable. The table can thus be formed by a substantially flat disc which co-acts with an opposite mould part placed opposite a flat side of the table. The opposite mould part is herein positioned above the edge of the disc-like table. The displaceable table is provided with at least one holder, but preferably at least two holders, for a carrier with electronic component. The disc can optionally also comprise three, four or even more than four holders, wherein these holders lie in the same plane through the displaceable (rotatable) table. A carrier with one or more components for encapsulating can now be laid on the displaceable table (or be connected in other manner to the displaceable table) and subsequently placed between co-acting mould parts by displacing the table. Other than in the prior art, the mould parts hereby only need to be moved apart over a relatively very short distance. Complex and expensive manipulation means (also referred to as handlers or loaders/offloaders) no longer require access between the co-acting mould parts owing to the displaceable table. A short stroke length of the mould (encapsulating device) makes it possible to simplify the drive means for the relative displacement of the mould parts. It is thus possible for the stroke length of the encapsulating device to be less than a few centimetres, or even less than one centimetre. A further advantage of the limited stroke length is that the time for relative displacement of the mould parts is limited, which results in shortening of the cycle time of an encapsulating operation. In addition, positioning of the carrier relative to the displaceable table no longer forms part of the critical path of an encapsulating operation, this being particularly the case if the table is provided with a plurality of holders. This also results in a further shortening of the cycle time of an encapsulating operation. It is desirable to give the mould part which co-acts with the displaceable table an easily exchangeable form. This is advantageous for instance when this mould part has to be thoroughly cleaned, i.e. a cleaning wherein ready access is available to the mould part for cleaning.

In a preferred variant of the encapsulating device, the displaceable table is provided with heating means for heating a carrier with electronic component. The integration of heating means with the displaceable table limits the number of essential operations with a carrier compared to the situation where use is made of a separate preheating position. The temperature of a carrier for processing can also be precisely controlled up to. the location of actual processing. The displaceable table can also be provided with cleaning means (for instance brushing means and/or suction means optionally displaceable relative to the table) with which the less readily accessible mould parts can be cleaned when the table is displaced.

In yet another preferred embodiment, the displaceable table is provided with at least one segment movable in a direction perpendicularly of a plane through the table and connected to the table, which segment is provided with a holder for a carrier with electronic component. Such a segment makes it possible to urge only the segment under a bias against an opposing mould part (in order to obtain the clamping force on the carrier required for the encapsulation) without the whole table being affected by this biasing force. An advantage of such a construction is for instance that it results in a simplified drive of the displaceable table, since in this preferrecl embodiment the construction of the drive is not mechanically loaded during clamping of a carrier for processing. In addition, this can also be advantageous in compensating effects of expansion resulting from (local) heating of the displaceable table.

It is also recommended that the frame is formed by a structure -which leaves clear an access to the space between the mould parts. The displaceable table can thus for instance engage on one side of the frame and an access can be left clear through the frame on the opposite side of the displaceable table. The frame can herein consist of a C-shaped construction wherein the opposite legs of the C engage on the separate mould parts. Such an open construction makes it possible for the dispLaceable table to protrude outside the frame. The table can hereby have a size which is optimized for the treatment process without this resulting in an extremely bulky frame. This also has the advantage that the mould parts can be placed in the encapsulating device for exchange in relatively simple manner (for change-over of the device and/or maintenance or cleaning of the encapsulating device). Another advantage is that the access to the displaceable table for loading and offloading thereof can be realized in more simple manner. The open construction of the frame is also made possible by shortening of the cycle time resulting from use of the displaceable table. The increased capacity enables the encapsulating. device to take a smaller form (fewer strips or carriers need be processed during a single processing cycle in order to nevertheless achieve the desired production capacity). A smaller mould (for instance a mould for processing only a single strip at a time) limits the forces required for clamping the carrier compared to larger encapsulating devices in which multiple carriers are processed simultaneously).

In yet another preferred embodiment, the drive means comprise a number of co-acting rotatable eccentrics. These eccentrics can be formed by a number of parallel rollers. The feed of the products for processing using a displaceable table makes it possible for the operating stroke of the encapsulating device to be very limited., this as already described above. The shorter stroke length now makes it possible to realize the relative displacement of the mould parts in economic manner while making use of a plurality of eccentrics. The use of a plurality of eccentrics makes it possibLe to support the mould part for displacement (or mould parts for displacement) at multiple positions, whereby the chance of deformation of such an engaged mould part is reduced. The possibility of applying a plurality of eccentrics in economically responsible manner in an encapsulating device arises now that the eccentrics only have to provide a relatively small displacement. The eccentrics are thus advantageous and only take up a small , volume, whereby a plurality of (for instance cylindrical) parallel eccentrics can engage on a mould part.

The invention also provides a method for encapsulating electronic components mounted on a carrier, comprising the processing steps of: A) positioning on a displaceable table a carrier with electronic component for encapsulating, B) displacing the table between a position, wherein a carrier with electronic component for encapsulating positioned on the table is left clear by a mould part co-acting with the table, to a position wherein the mould part lies opposite the carrier with electronic component for encapsulating, C) reducing the mutual distance between the table and the mould part co-acting with the table such that the carrier with electronic component for encapsulating is enclosed therebetween, and D) feeding encapsulant to a mould cavity connecting to the carrier and the electronic component for encapsulating. The table herein preferably comprises a rotating movement component during processing step B). The advantages as described . above in respect of the encapsulating device according to the invention can be realized by means of this method. The displacement of the table does not here need to form an additional operation compared to the prior art, and can moreover be advantageously combined with preheating of the carrier and/or cleaning of the encapsulating device.

In a preferred application of the method according to the invention, the mutual distance between the table and the mould part co-acting with the table is reduced by rotating a number of eccentrics engaging on the mould part. It is noted that this method can of course also be reversed by having the eccentrics engage on the table, and thus displacing the table relative to the opposite mould part.

The invention will be further elucidated on the basis of the non-limitative exemplary embodiments shown in the following figures, in which: figure 1 A shows a schematic front view of an encapsulating device according to the present invention, figure IB shows a schematic side view of the encapsulating device of figure 1A,. figure 2 shows a schematic perspective view of an alternative embodiment variant of the encapsulating device according to the present invention, figure 3 shows a cross-section through a part of an encapsulating device with a rotatable table provided with a displaceable segment,

figure 4A shows a schematic top view of a two-fold rotatable table of an encapsulating device according to the invention, and figure 4B shows a schematic top view of a four-fold rotatable table of an encapsulating device according to the invention.

Figure 1A shows a front view of an encapsulating device 1. This latter is provided with a frame 2 on which supports a table 4 rotatable about a shaft 3. Placed on rotatable table 4 is a holder 5 for supporting a carrier 6 with electronic components (not shown in this figure), such as semiconductor circuits in particular. An upper mould part is located above rotatable table 4. Both holder 5 and upper mould part 7 are normally provided with heating means which are not shown in this figure. The upper mould part 7 is, connected to a displaceable block 8 on which four eccentrics 9 engage. By rotating the eccentrics 9 the block 8 will be displaced relative to frame 2, with the result that carrier 6 is clamped between upper mould part 7 and holder 5 such that the conditions are present for begimiing the actual encapsulation of the electronic components. Supply means 11 and discharge means 12 for foil material 13 are also shown. Foil material 13 is desirable in determined conditions to protect mould parts and/or components of the products for processing. Instead of using a single layer of foil material 13, it is also possible to opt for performing the encapsulating process without foil material or with two foil layers.

Figure IB shows encapsulating device 1 in side view. Here can be seen that rotatable table 4 is provided with a plurality of holders 5, which holders 5 are each individually adapted to support a carrier 6 with electronic components for encapsulating. The substantially C-shaped configuration of frame 2 is also clearly visible. Frame 2 is provided with a guide 14 along which the block 8 supporting upper mould part 7 is displaceable. Upper mould part 7 is preferably embodied, although this is not shown in this figure, such that it can be readily exchanged. This is possible for instance by coupling mould part 7 releasably via a "drawer construction" to supporting block 8.. Figure 2 shows a perspective view of an encapsulating device 20 with a frame 21 on which an upper mould part 22 is mounted for displacement via an operating cylinder 23. Upper mould part 22 engages on guides 24 forming part of frame 21. A table 26 rotatable about a rotation shaft 25 is also mounted on frame 21. Arranged on the tables are three holders 27 (although an even number of holders 27 would be more logical) for supporting leadframes or boards not shown in this figure.

Figure 3 shows a cross-section through the displaceable table 30 with a segment 31 which is releasable from the remaining part of table 30. Segment 31 is provided with a holder position 32 for leadframes and with schematically represented heating means 33 with which a carrier supported by segment 31 can be heated. When segment 31 with heated leadframe is placed below an upper mould part 34, a pusher plate 35 located under segment 31 can be moved upward by rotating the eccentrics 36. Segment 31 is hereby moved toward upper mould part 34, while the position of the remaining part of the table does not change. The product lying on segment 31 can thus be urged against upper mould part 34, whereafter encapsulant can be fed by means of the feed means 37, which are shown only very schematically. An alternative feed for the encapsulant runs through a runner 38 arranged in upper mould part 34. The advantage of the table 30 with one or more releasable segments 31 is that the table 30 as a whole is not loaded by the forces with which products are clamped, with the result that the suspension of the table can be simple and the construction can take a relatively light form.

Figure 4A shows a schematically represented rotatable table 41 such as forms part of an encapsulating device according to the invention. Table 41 is provided with two holder positions 42 for leadframes 43, 44, wherein a first leadframe 43 has not yet been processed and a second leadframe 44 is provided with encapsulant 45.

Figure 4B likewise shows a schematic top view of a rotatable table 61 such as forms part of an encapsulating device according to the invention. The rotatable table 61 is provided with four holder positions 62 for leadframes 43, 44, wherein the first leadframes 43 have not yet been processed in encapsulating device 60 and second leadframes 44 are provided with encapsulant 45.

Claims

1. Encapsulating device for encapsulating electronic components mounted on a carrier, comprising:

- a frame,

- two mutually displaceable mould parts connected to the frame,

- drive means for mutually displacing the mould parts, and

- feed means for encapsulant connecting to at least one of the mould parts, wherein one of the mould parts comprises a displaceable table.

2. Encapsulating device as claimed in claim 1 , characterized in that the displaceable table is rotatable.

3. Encapsulating device as claimed in claim 1 or 2, characterized in that the displaceable table is provided with at least one holder for a carrier with electronic component.

4. Encapsulating device as claimed in claim 3, characterized in that the displaceable table is provided with at least two holders for a carrier with electronic component.

5. Encapsulating device as claimed in any of the foregoing claims, characterized in that the displaceable table is provided with heating means for heating a earner with electronic component.

6. Encapsulating device as claimed in any of the foregoing claims, characterized in that the displaceable table is provided with at least one segment movable in a direction perpendicularly of a plane through the table and connected to the table, which segment is provided with a holder for a carrier with electronic component.

7. Encapsulating device as claimed in any of the foregoing claims, characterized in that the frame is formed by a structure which leaves clear an access to the space between the mould parts.

8. Encapsulating device as claimed in claim 7, characterized in that the displaceable table engages on one side of the frame and an access is left clear through the frame on the opposite side of the displaceable table.

9. Encapsulating device as claimed in claim 7 or 8, characterized in that the frame comprises a C-shaped construction wherein the opposite legs of the C engage on the separate mould parts.

10. Encapsulating device as claimed in any of the foregoing claims, characterized in that the drive means comprise a number of co-acting rotatable eccentrics.

11. Encapsulating device as claimed in claim 10, characterized in that the eccentrics are formed by a number of parallel rollers.

12. Method for encapsulating electronic components mounted on a carrier, comprising the processing steps of:

A) positioning on a displaceable table a carrier with electronic component for encapsulating,

B) displacing the table between a position, wherein a carrier with electronic component for encapsulating positioned on the table is left clear by a mould part co-acting with the table, to a position wherein the mould part lies opposite the carrier with electronic component for encapsulating,

C) reducing the mutual distance between the table and the mould part co-acting with the table such that the carrier with electronic component for encapsulating is enclosed therebetween, and

D) feeding encapsulant to a mould cavity connecting to the carrier and the electronic component for encapsulating.

13. Method as claimed in claim 12, characterized in that the table comprises a rotating movement component during processing step B).

14. Method as claimed in claim 12 or 13, characterized in that the mutual distance between the table and the mould part co-acting with the table is reduced by rotating a . number of eccentrics engaging on the mould part.