WO1997035703A1

WO1997035703A1 - Mould assembly and method for use thereof

Info

Publication number: WO1997035703A1
Application number: PCT/NL1997/000143
Authority: WO
Inventors: Wilhelmus Hendrikus Johannes Harmsen; Martin Herman Weggen; Johannes Lambertus Martinus Dannenberg; Albertus Franciscus Gerardus Van Driel
Original assignee: Fico BV
Current assignee: Fico BV
Priority date: 1996-03-22
Filing date: 1997-03-19
Publication date: 1997-10-02
Anticipated expiration: 1998-09-22
Also published as: AU1947297A; NL1002690C2

Abstract

The invention relates to a mould assembly for encapsulating electronic components mounted on so-called lead frames, comprising: support elements which can be coupled to the sides of the two mould halves remote from the sides closing onto each other. The invention also comprises a method for placing at least a part of such a mould assembly in a pressing device. Another aspect of the invention relates to a mould assembly comprising a base in which can be placed a carriage having at least one mould cavity. Another aspect of the invention relates to a mould assembly wherein a plunger can be connected releasably to a plunger carrier.

Description

MOULD ASSEMBLY AND METHOD FOR USE THEREOF

The invention relates to a mould assembly for encap¬ sulating electronic components mounted on so-called lead frames, comprising:

- two mould halves movable relative to each other and closable onto each other by means of a device.

The invention also relates to a method for placing at least a part of such a mould assembly in a pressing device .

Large pressing devices are generally used for encap- sulating electronic components mounted on so-called lead frames. In order to encapsulate a plurality of products it is possible to mount different mould assemblies in such a pressing device. A specific mould assembly must herein be present for each product for encapsulating. Encapsulation of the electronic components takes place by heating an encapsulating material which is arranged in a mould part and subsequently placed under pressure by means of a plunger, whereby the liquefied encapsulating material flows via feed channels to one or more mould cavities. In addition to moving the mould halves of the mould assembly relative to each other the pressing device also effects the movement of the plunger or plungers. During change-over of a pressing device a mould assembly is removed from the pressing device, whereafter another mould assembly is placed in the pressing device. A limi¬ tation of the existing devices is that the position at which the pressing device engages the plungers is fixed. This limits the change-over options since only mould assemblies can be used wherein the plunger configuration is chosen such that the plungers can be engaged by the pressing device to exert pressure on the encapsulating material. A plurality of plungers are generally situated in a row but this is not necessary. In practice diverse mould assemblies are used with standard plunger configu- rations. Examples hereof are a mould assembly with a central plunger row, a mould assembly with two parallel plunger rows placed equidistantly from the middle, a very usual mould assembly with four parallel plunger rows etcetera. Change-over of an existing pressing device from a situation in which a mould assembly with a single central plunger row is clamped to a situation in which a mould assembly with two parallel plunger rows is clamped requires a very time-consuming conversion of the pressing device.

The present invention has for its object to provide a mould assembly and a method for placing such a mould assembly in a pressing device whereby mould assemblies with diverse plunger configurations can be operated in very simple manner. It is also an object of the invention to provide a mould assembly which during use will not deform or hardly at all.

The present invention provides for this purpose a mould assembly of the type stated in the preamble, also comprising:

- support elements which can be coupled to the sides of the mould halves remote from the sides closing onto each other, and

- at least one plunger carrier which is movable between the support elements coupled to one mould half and to which at least one plunger is fixed for co-action with a continuous recess in a mould half.

In the method according to the invention a location is determined subject to a plunger configuration of one of the mould halves where support elements are arranged between a mould half base of the mould half and the pressing device . The support elements are displaceable relative to the other mould assembly parts, in particular the "basic parts" in which the mould openings are ar- ranged. Depending on the plunger configuration of the mould assembly the support elements are placed such that they leave space for the passage of plunger drive and/or plungers. The displaceability of the support elements makes it possible to adapt the position thereof to the specific plunger configuration. That is, the support elements do not have to be displaced during a change-over between mould assemblies with the same plunger configura- tion. In that case only the product-dependent part of the mould assembly has to be changed over. A part of the mould assembly, including the support elements, does not therefore have to be removed when the mould assemblies form part of the same plunger configuration family. This first of all simplifies change-over of mould assemblies within the same plunger configuration family but also enables change-over between two mould assemblies which can be classified into differing plunger configuration families. This means for instance that first a mould assembly with a single row of plungers is used whereafter a mould assembly with two rows of plungers can be used. It is of course then necessary herein to displace the support elements such that the respective rows of plung¬ ers are left clear by the support elements. An additional advantage of the displaceable support elements is that they can be disposed such that the mould assembly is well supported. In existing devices having the same freedom of change-over the mould assembly still has to be left clear at the possible locations of the plungers. In the mould assembly according to the present invention the support thereof can be realized directly beside the plungers.

In a preferred embodiment of the mould assembly at least one ejector rod carrier movable parallel to the plunger carrier is connected to one of the mould halves by at least one ejector rod by means of which ejector pins present in a mould half can be operated to release an encapsulated product and/or encapsulating material from a mould cavity. While retaining the above stated advantages, this construction also enables operation of the ejector pins in a mould assembly irrespectively of the plunger configuration and/or the position(s) where the drive means for the ejector pins engage the mould assembly. The invention also provides great flexibility in respect of the configuration of contact points for the ejector pm drive.

In a preferred embodiment of the mould assembly the mould halves comprise:

- a base on which the support elements engage adapted to receive at least one carriage,

- at least one carriage placeable in the base and having at least one mould cavity, and - locking means for locking the carriage in the base.

In a further preferred embodiment the locking means comprise :

- profile edges arranged in the base in which the car¬ riage is slidable from one side of the base, - counter-profile edges forming part of the carriage and co-acting with the profile edges in the base, and

- a cover element fixable to the side of the base on which the carriage is closable in the base.

A separation of the mould halves in a base in which at least one carriage is received results in the possi¬ bility of replacing (SMED) product-dependent mould cavi¬ ties with mould cavities of other dimensions in very simple manner without a large part of the mould assembly having to be removed and displaced. A condition herein is however that the plunger configuration, and preferably also the configuration of contact points for the ejector pins, are the same beyond the products for encapsulating. In this case it is possible to speak of the same family of products in terms of mould assembly construction. Within the same mould assembly family, support elements and plunger carrier (s) do not have be removed and re-placed when the described construction is used. If the plunger configurations are exactly the same before and after change-over, it is likewise unnecessary to remove and replace the plunger carrier (s) . It is however also possible that within the same mould assembly family the plungers are located in the same line(s) of operation before and after change-over but that the plungers are situated at different positions on the line of operation. In this latter case it will also be necessary to remove and replace the plunger carrier (s) . We can however still speak in this case of the same mould assembly family. Another embodiment according to the invention re¬ lates to a mould assembly for encapsulating electronic components mounted on so-called lead frames, which mould assembly comprises two mould halves movable relative to each other and closable onto each other, a first mould half of which is provided with at least one recess for receiving encapsulating material on which pressure can be exerted and of which the contact surface of a second mould half is formed, at least at the position where it connects onto the recess for encapsulating material, by a plate-like element which protrudes relative to the en¬ closing mould half surface and which is connected to the second mould half by at least one elastically deformable element. The elastically deformable element is preferably hollow cylindrical and manufactured from metal . In anoth- er preferred embodiment the plate-like element has an elongate form and is connected to the second mould half by a plurality of elastically deformable elements. The plate-like element which is placed opposite the recess in which the encapsulating material is placed under pressure by means of a plunger will be urged against the opposite mould half with a bias to be determined by the at least one elastically deformable element when the mould halves close. If the elastically deformable element has a suffi¬ ciently great spring constant a very good connection of the plate-like element to the opposite mould half can be obtained in this manner. Particularly at the position where the encapsulating material is placed under pressure there is a relatively large chance of a component with a relatively low viscosity flowing out of the encapsulating material and out between the mould halves. A layer hereby remaining behind on one of the mould halves after encap¬ sulating is relatively difficult to remove and can result in a reduced quality of the encapsulated product in a subsequent production run. To now prevent such a thin layer penetrating between the two mould halves a very good connection is desirable close to the recess in which the encapsulating material is brought under pressure. Such a good connection can be obtained using said steps. The advantage of the elastically supported plate-like element is that it provides a good seal between the two mould halves close to the recess for receiving encapsu¬ lating material, whereby the risk of contamination of the mould halves is reduced.

An elastically deformable element manufactured from metal with a hollow cylindrical shape can be embodied such that a sufficiently large spring constant can be obtained. The advantage of this construction is also that a hollow cylindrical element can be ground very precisely to length, thus enabling an accurate positioning of the plate-like element in one of the mould halves. Such an accurate dimensioning of the elastically deformable elements is of particular importance when the plate-like element is elongate and supported by a plurality of deformable elements. An elongate plate-like element can be used for connection to a plurality of recesses for encapsulating material .

Another aspect of the invention relates to a mould assembly for encapsulating electronic components mounted on so-called lead frames, which mould assembly comprises two mould halves movable relative to each other and closable onto each other, wherein at least one continuous recess runs through a first mould half and in the recess is received a plunger part provided with coupling means for connecting the plunger part releasably to a plunger carrier. The first mould half preferably also comprises locking means for locking a plunger part in the first mould half. In the prior art a plunger part is generally fixedly connected to the plunger carrier or can only be released therefrom or fixed thereto in very time-consum¬ ing manner. In practice this means that when one or more plungers are replaced the plunger carrier also has to be removed from the device driving the mould assembly. Another plunger carrier with at least one plunger can subsequently be placed in the device or it is possible to fix one or more deformed plunger parts to the plunger carrier outside the device driving the mould assembly, whereafter the plunger carrier can be re-placed in the device. The present invention has for its object to provide an improved construction wherein a plunger part can be released from the plunger carrier in simple man- ner.

Using the described construction a plunger part can be released from the plunger carrier in very simple manner. This has the advantage that during replacement of at least a part of the mould assembly the plunger carrier does not have to be exchanged. It can remain in the device driving the mould assembly, whereby such a change¬ over can be realized more quickly. Another advantage is that the construction height of the device driving the mould assembly can be limited by this construction. It is after all possible to leave a plunger part in a mould half when mould halves are placed into respectively taken out of the driving device. The result hereof is that the plunger carrier does not have to be moved so far away from the mould halves that the plungers are completely released from the mould half in which continuous recesses are arranged. A part of the plungers can remain behind in this mould half when it is removed from the device. The plunger carrier is thereby not required to be able to make such a large stroke. This limits the construction height of the driving device. Yet another advantage of the present construction is that the risk of damage to the plunger parts is limited in that they are arranged in a mould half even when they are removed from the device. This mould half prevents damage to the usually vulnerable plunger parts. In addition to the stated time-saving during conversion, the fact that a plunger carrier re¬ mains behind during change-over between two mould assem¬ blies of the same family also has the advantage in re- spect of the plunger configuration family that the usual¬ ly voluminous plunger carrier is already at temperature after the machine has been converted. This makes it possible to produce more quickly after change-over than with devices according to the prior art.

In a preferred embodiment of a mould assembly the locking means comprise a plate which is slidable substan¬ tially perpendicularly of the plunger part, which plate is provided with an opening for passage of the plunger part having a narrowed opening portion for co-action with a narrowed portion of the plunger part. Such a slidable plate is relatively very simple to construct and in simple manner the plunger part can also be prevented from locking at an undesirable moment. This will be further elucidated in the following figure description.

In a preferred embodiment the mould assembly also comprises the plunger carrier provided with coupling means for co-action with coupling means of the plunger part. As desired, the plunger carrier may or may not form part of the mould assembly, depending on the diversity of mould assembly families (in respect of the plunger con¬ figuration thereof) . It is thus possible in situations in which only one plunger configuration is applied in a device driving the mould assembly to have the plunger carrier form part of the driving device. In the case of a greater diversity in mould assembly families (in respect of plunger configuration) it may be advisable to have the plunger carrier form part of the mould assembly. This invention relates emphatically to a mould assembly where- in the plunger carrier forms no part of the mould assem¬ bly as well as to a mould assembly wherein the plunger carrier does form part of the mould assembly.

Particularly advantageous is the embodiment of the mould assembly wherein the mould half with continuous opening comprises:

- a base on which support elements engage adapted for receiving at least one carriage, - at least one carriage placeable in the base and having at least one mould cavity, and

- locking means for locking the carriage in the base, wherein the plunger part with the locking means is ar- ranged in the carriage.

In addition to the advantages of rapid exchange of the carriage as already described above, this construc¬ tion has the advantage that at least one plunger part can be removed with the carriage. An advantage which likewise applies for the other mould assemblies with connectable plunger part is that with this construction the plunger part always co-acts with one and the same continuous opening in a mould half. An optimum fit can thereby be obtained between mould half and plunger part. When a plunger is used in a plurality of continuous openings, this fit will on average be less precise.

Yet another aspect of the invention relates to a method for placing a carriage forming part of a mould assembly for encapsulating electronic components mounted on so-called lead frames, which mould assembly comprises two mould halves movable relative to each other and closable onto each other as specified above, comprising the steps of :

- placing the plunger carrier in a coupling position such that the coupling means of the plunger carrier are posi¬ tioned for co-action with the coupling means of the plunger part,

- placing the carriage in the base, wherein the plunger part is locked in the carriage by the locking means such that the coupling means of the plunger part engage the coupling means of the plunger carrier, and

- releasing the locking means whereby the plunger part is movable by the plunger carrier.

In addition to the method for placing the carriage the invention also comprises a method for removing the carriage forming part of a mould assembly for encapsulat¬ ing electronic components mounted on so-called lead frames, which mould assembly comprises two mould halves movable relative to each other and closable onto each other as specified above, comprising the steps of:

- placing the plunger carrier in an uncoupling position such that the coupling means of the plunger carrier are positioned for uncoupling the plunger part and the plung¬ er carrier,

- securing the plunger part in the carriage with the locking means, and

- taking the carriage with the plunger part locked there- in out of the base, whereby the coupling means of the plunger part and the coupling means of the plunger carri¬ er are released from each other.

By means of a few very simple operations, which can thus be performed quickly, it becomes possible to place respectively take out a carriage. Using the methods the above mentioned advantages can be realized, i.e. quick change without long wait times or complex constructions for temperature compensation, less risk of damage to the plungers and the possibility of using an encapsulating device of limited height.

The above described mould assemblies and methods will be further elucidated with reference to the non- limitative embodiments shown in the following figures. Herein: Fig. 1 shows a perspective view of a mould assembly according to the invention;

Fig. 2 shows a partly cut-away perspective view of a pressing device in which the mould assembly according to figure 1 is arranged; Fig. 3 shows a perspective view of a mould half, partly dismantled into parts, forming part of the mould assembly of figure 1;

Fig. 4 is a cut-away perspective view of the mould half shown in figure 3 in assembled state; Fig. 5 is a perspective view of a construction included in a preferred embodiment of the mould assembly according to the invention, and Fig. 6 is a perspective view of a drive included in a preferred embodiment of the mould assembly according to the present invention.

Fig. 1 shows a mould assembly 1 comprising an upper mould half 2 and a lower mould half 3 which are movable relative to each other and closable onto each other. The upper mould half 2 and the lower mould half 3 can be fixed to a pressing device (not shown in this figure) by respective fixing plates 70,71. Both upper mould half 2 and lower mould half 3 are provided with respective support elements 4,5. The position of support elements 4,5 is not fixed; the position of support elements 4,5 in upper mould half 2 and lower mould half 3 is variable. The position in which support elements 4,5 are placed depends particularly on the form of the active surfaces

6,7 of upper mould half 2 and lower mould half 3. Partic¬ ularly the continuous recesses 8 which are arranged in the active surface 7 of lower mould half 3 and in which plungers (not shown in this figure) are movable to place encapsulating material under pressure must be left clear by support elements 5. Between support elements 5 and under the continuous openings 8 are arranged plunger beams 9 on which are fixed the plungers movable in open¬ ings 8. When the active surfaces 6,7 are exchanged for other active surfaces wherein particularly the plunger openings 8 are situated in the same positions as in active surface 7, it is not necessary to change the position of support elements 4,5 in respectively upper mould half 2 and lower mould half 3. Also when the posi- tion of plunger openings 8 changes to a limited extent, i.e. when they are located in the rows situated at the same positions as those in which the rows of plunger openings 8 were situated before change-over, the displac¬ ing of support elements 4,5 can be dispensed with. Only when after exchange of the active surfaces 6,7 the plung¬ er openings 8 are situated at a position where a support element 5 supports the active surface 7 is it necessary to move support elements 5. For a good balancing of mould assembly 1 the support elements 4 in upper mould half 2 will have to be placed such that they are located above support elements 5.

Also shown in the mould assembly 1 of figure 1 are ejector beams 10,11 to which are fixed ejector rods 12,13. Ejector pins (not shown in this figure) can be moved by means of the ejector beams 10,11 and ejector rods 12,13, whereby objects can be released from the active surfaces 6,7. This will be further elucidated with reference to figure 4. The support elements 4,5 must also leave space free for the ejector beams at the location of the ejector rods 12. The plunger beams 9 are mutually coupled by means of a collective plunger beam support 14. When it is unnecessary to change the position of plunger beams 9 during a change-over, the fixing of plunger beams 9 to plunger beam support 14 can also remain intact. When it is however necessary to change the position of plunger beams 9 they must be fixed to plunger beam support 14 at different positions. For this purpose there are plunger beam support parts 15 which are fixable to plunger beam support 14 and whereby the position of plunger beams 9 is determined. The plunger beam support elements 15 are thus family-dependent and only have to be replaced by others when the position of plunger beams 9 changes. Ejector beams 10,11 are also coupled by means of ejector beam supports 16,17. In order to cause the ejec¬ tor beams 10,11 to move, drives can be arranged in mould assembly 1, the embodiment of which is shown in figure 6. It is also possible however to place the drive of ejector beams 10,11 in a device driving the mould assembly 1 instead of in mould assembly 1. The mould assembly fur¬ ther has centering pins 18 fixed to lower mould half 3 which co-act with centering grooves 19 fixed to upper mould half 2. For fine-centering, fine-centering pins 20 are also arranged in lower mould half 3 which co-act with fine-centering grooves 21 in the same manner as centering pins 18 co-act with centering grooves 19. This figure also shows protruding strips 22 which form part of the active surface 6 of upper mould half 2. These protruding strips 22 will be further described with reference to figure 5.

Fig. 2 shows a pressing device 23 in which the mould assembly 1 is accommodated. Pressing device 23 with mould assembly 1 accommodated therein are shown in the pressing position. The upper mould half 2 is partly broken away to give a better view of lower mould half 3. The lower mould half 3 is vertically displaceable in a frame 24 of press- ing device 23 for opening and closing of mould halves

2,3. This opening is necessary for placing of the elec¬ tronic components for encapsulating, applying of encapsu¬ lating material and removal of the encapsulated products after the encapsulating process. Arranged in the frame 5 of pressing device 23 is a geared motor 25 for causing the lower mould half 3 to move vertically. Also shown in pressing device 23 are means 26 whereby the plungers, which are likewise not shown in this figure, can be displaced and can exert pressure on the encapsulating material placed in plunger openings 8 in lower mould half 3. The means 26 for driving the plungers comprise four vertical screw spindles 27 which are driven by a central motor 29 by means of belts 28. The plunger beam supports 14 are vertically displaceable in synchronous manner by means of rotating the screw spindles 27. Pressing device 23 represents independently of the mould assembly 1 an invention for which patent is likewise applied. Pressing device 23 is only shown here to elucidate the operation of the mould assembly 1 and does not form part of the present invention.

Fig. 3 shows the lower mould half 3 in dismantled state. Clearly visible in this figure are the plunger beams 9 which are detached from the plunger beam support 14 and plunger beam support element 15. Situated on plunger beams 9 are plunger coupling parts 30 which can be coupled to plungers 31, one of which is shown in broken lines. The plungers 31 are situated in a carriage 32, which carriage 32 forms part of the active surface 7 of lower mould half 3. In addition to the plunger open¬ ings 8 shown in fig. 1, mould cavities 33 are also shown in this figure. Plungers 31 urge encapsulating material placed in the plunger openings 8 through channels 34 to the mould cavities 33. Carriage 32 is provided with profile edges 35 for co-action with guides 36 in a base 37. Carriage 32 can be pushed into the base 37 whereby coupling elements 38 mounted on ejector rods 12 engage in a rail 39 which forms part of carriage 32. The rail 39 is connected to the ejector pin which is not shown in this figure. By means of moving ejector rods 12 the ejector rail 39 will also move whereby the ejector pins will also move. Before carriage 32 can be pushed into base 37 the plunger beams 9 must first be placed on the plunger beam support 14. Plunger beams 9 must then be moved upward such that the plunger coupling means 30 protrude through the slots 40 in base 36. When the plunger coupling means 30 are brought to the correct height the carriage 32 can be placed in base 37. Plungers 31 will herein engage on plunger coupling means 30. After carriage 32 has been placed completely in base 37 and plunger coupling means 30 are coupled to plungers 31, the locking means 41 with which until that moment the plungers 31 were locked in carriage 32 can be placed in an uncoupled position. That is, after uncoupling of locking means 41 the plungers 31 are movable in the carriage 32 by a vertical displacement of plunger beams 9. Finally, a closing strip 42 must be fixed to the base 37 in order to fix carriage 32 in base 37. Placing of this closing strip 42 will also place the locking means 41 in an uncoupled position. This prevents damage to mould assembly 1 as a result of accidentally not uncoupling the plungers 31 in carriage 32.

Fig. 4 shows a view in cross section of the carriage 32 placed in the base 37. It can be seen clearly that the plunger coupling parts 30 are connected to plungers 31 in that feet 43 on the underside of plungers 31 engage in recesses 44 arranged in plunger coupling parts 30. It will be apparent that a coupling between plunger 31 and plunger coupling part 30 is then only possible when plunger coupling parts 30 are placed at exactly the right height when carriage 32 is pushed into base 37 so that the feet 43 are situated at precisely the height of recesses 44. The locking means 41 serve to prevent the plungers 31 being able to fall out of carriage 32 when this latter is removed from the base 37. Coupling means 41 consist of a strip 45 in which recesses 46 are ar¬ ranged. Recesses 46 are provided with an opening portion with a cross section which is at least as large as the cross section of plunger 31 at the height of strip 45. Recesses 46 also comprise an opening portion which con¬ nects to the above described opening portion which is smaller than the cross section of plungers 31 at the height of strip 45. This narrowed opening portion of recesses 46 can co-act with the reduced portions 47. When the strip 45 is placed such that the narrowed opening portions of recesses 46 co-act with the reduced portions 47 of plungers 31, the plungers 31 are situated in the locked situation. By displacing the strip 45 the opening portion of recess 46 with the enlarged cross section can be placed in line with plungers 31. At that moment the plungers 31 are in uncoupled situation. Placing of the closing strip 42 inevitably urges the strip 45 forward such that plungers 31 are in uncoupled situation when the closing strip 42 is placed.

Fig. 4 also shows ejector pins 48 which are mutually connected by means of an ejector plate 49. The rail 39 engages on the ejector plate 49. A minimal vertical movement of ejector rods 42 will be transmitted by the coupling elements 38 to the rail 39. The relatively limited vertical movement of rail 39 results in the ejector plate 49 also moving whereby ejector pins 48 will also move. The movement of ejector pins 48 in mould cavity 33 is required to release products formed in mould cavity 33. By means of the ejector pins 48 the electronic element encapsulated with encapsulating material can be pushed loose of the active surface 7. The use of ejector pins 48 prevents unnecessary damage to the encapsulated products .

Fig. 5 shows the protruding strip 22 on the surface 6 of upper mould half 2. The protruding strip is dis- placed such that it is situated above plunger openings 8. The strip 22 completely covers the plunger openings 8. The surface of the protruding strip 22 facing toward lower mould half 3 is not completely in line with the remaining part of active surface 6 but protrudes a very limited distance over the remaining part of the surface 6. The protruding strip 22 is supported on upper mould half 2 with interposing of resilient elements 50, here in the form of hollow cylindrical bushes. When the mould halves 2,3 are closed onto each other the protruding strip 22 will first be urged against the active surface 7 of lower mould half 3. As the closing force between mould halves 2,3 increases, the resilient elements 50 will be pressed in. In this manner a very good connection of the protruding strip 22 to the active surface 7 of lower mould half 3 is obtained. It is also possible by means of resilient elements 50 to determine precisely how great this closing force is. This is all particularly desirable for obtaining a very good sealing on the plunger openings 8. This is to prevent a very fluid fraction of the encap- sulating material placed in plunger openings 8 from penetrating between mould halves 2,3. The advantage of the chosen construction in terms of the spring elements 50 is that these can be brought to length relatively inexpensively and very accurately, whereby a uniform connection of the protruding strip 22 along its whole length onto the active surface 7 of lower mould half 3 is possible .

Finally, fig. 6 shows a drive 51 with which a rela¬ tively limited vertical movement of beams 54 can be realized by rotation of shafts 52 on which are mounted eccentrics 53. Such a relatively limited vertical move¬ ment of beams 54 can be employed particularly advanta¬ geously to drive the ejector rods 12. This can be real- ized by coupling the ejector beams 10 to beams 54 or by replacing beams 54 with the ejector beams 10. This drive

51 can be accommodated in lower mould half 3 but it is also possible to connect the drive 51 to pressing device

20. Drive 51 is exceptionally compact and structurally simple to realize.

*****

Claims

1. Mould assembly for encapsulating electronic components mounted on so-called lead frames, comprising:

- two mould halves movable relative to each other and closable onto each other by means of a device, - support elements which can be coupled to the sides of the mould halves remote from the sides closing onto each other, and

2. Mould assembly as claimed in claim 1, wherein at least one ejector rod carrier movable parallel to the plunger carrier is connected to one of the mould halves by at least one ejector rod by means of which ejector pins present in the mould half can be operated to release an encapsulated product and/or encapsulating material from a mould cavity.

3. Method for placing at least a part of a mould assembly as claimed in claim 1 or 2 in a pressing device, wherein subject to a plunger configuration of one of the mould halves the location is determined where support elements are arranged between a mould half base of the mould half and the pressing device.

4. Mould assembly as claimed in claim 1 or 2, where¬ in the mould halves comprise:

- at least one carriage placeable in the base and having at least one mould cavity, and

- locking means for locking the carriage in the base.

5. Mould assembly as claimed in claim 3, wherein the locking means comprise: - profile edges arranged in the base in which the car¬ riage is slidable from one side of the base,

- counter-profile edges forming part of the carriage and co-acting with the profile edges in the base, and - a cover element fixable to the side of the base on which the carriage is closable in the base.

6. Mould assembly for encapsulating electronic components mounted on so-called lead frames, which mould assembly comprises two mould halves movable relative to each other and closable onto each other, a first mould half of which is provided with at least one recess for receiving encapsulating material on which pressure can be exerted and of which the contact surface of a second mould half is formed, at least at the position where it connects onto the recess for encapsulating material, by a plate-like element which protrudes relative to the en¬ closing mould half surface and which is connected to the second mould half by at least one elastically deformable element .

7. Mould assembly as claimed in claim 5, wherein the elastically deformable element is hollow cylindrical.

8. Mould assembly as claimed in claim 5 or 6, where¬ in the elastically deformable element is manufactured from metal .

9. Mould assembly as claimed in any of the claims 5- 7, wherein the plate-like element has an elongate form and is connected to the second mould half by a plurality of elastically deformable elements.

10. Mould assembly for encapsulating electronic components mounted on so-called lead frames, which mould assembly comprises two mould halves movable relative to each other and closable onto each other, wherein at least one continuous recess runs through a first mould half and in the recess is received a plunger part provided with coupling means for connecting the plunger part releasably to a plunger carrier.

11. Mould assembly as claimed in claim 9, wherein the first mould half comprises locking means for locking the plunger part in the first mould half.

12. Mould assembly as claimed in claim 9 or 10, wherein the locking means comprise a plate which is slidable substantially perpendicularly of the plunger part, which plate is provided with an opening for passage of the plunger part having a narrowed opening portion for co-action with a reduced portion of the plunger part.

13. Mould assembly as claimed in any of the claims 9-11, wherein the mould assembly also comprises the plunger carrier provided with coupling means for co- action with the coupling means of the plunger part.

14. Mould assembly as claimed in any of the claims 9-12, wherein the mould half with continuous opening comprises :

- a base on which support elements engage adapted for receiving at least one carriage,

- locking means for locking the carriage in the base, wherein the plunger part with the locking means is ar¬ ranged in the carriage.

15. Method for placing a carriage forming part of a mould assembly for encapsulating electronic components mounted on so-called lead frames, which mould assembly comprises two mould halves movable relative to each other and closable onto each other as claimed in claim 13, comprising the steps of : - placing the plunger carrier in a coupling position such that the coupling means of the plunger carrier are posi¬ tioned for co-action with the coupling means of the plunger part,

- placing the carriage in the base, wherein the plunger part is locked in the carriage by the locking means such that the coupling means of the plunger part engage the coupling means of the plunger carrier, and - releasing the locking means whereby the plunger part is movable by the plunger carrier.

16. Method for removing a carriage forming part of a mould assembly for encapsulating electronic components mounted on so-called lead frames, which mould assembly comprises two mould halves movable relative to each other and closable onto each other as claimed in claim 13 , comprising the steps of :

- securing the plunger part in the carriage with the locking means, and - taking the carriage with the plunger part locked there¬ in out of the base, whereby the coupling means of the plunger part and the coupling means of the plunger carri¬ er are released from each other.

*****