HK1014080A - Modular moulding apparatus - Google Patents

Description

The present invention relates to an apparatus for moulding lead frames comprising at least one mould formed by two mould halves movable relative to one another, means for introducing a lead frame into one of the mould halves, means for carrying encapsulating material into the cavities of the mould, means for exerting pressure in these cavities, means for heating the mould halves, means for cleaning the mould halves and means for removing an encapsulated product from the mould.

Such an apparatus is already known and is described for instance in the European patent application 89203003.2 of the same applicant as the present case. Such a moulding apparatus combines a simple structure with a relatively high production speed. A drawback to this moulding apparatus is that over a period of time the capacity thereof cannot be adapted to changing requirements. Another drawback is that when one component of the moulding apparatus malfunctions the entire moulding apparatus ceases to function. The susceptibility to malfunction is required to be exceptionally low and considerable effort must be made with existing apparatus to comply with this requirement. In addition, the moulding apparatus is wholly idle during switch-over to a different product.

The present invention has for its object to provide a moulding apparatus which is less susceptible to malfunction during use, which can be adjusted to another product with minimum loss of productivity, and the capacity of which can be adapted to changing requirements. A following objective is to provide a moulding apparatus which can be coupled to processing units, e.g. for further processing or controlling the quality of an encapsulated product.

The present invention provides for this purpose a moulding apparatus of the type stated in the preamble wherein the means for introducing a lead frame into one of the mould halves, the means for carrying encapsulating material into the cavities of the mould and the means for removing an encapsulated product from the mould are arranged on at least one carriage movable along a guide relative to the mould halves, which carriage provided with means serves at least one mould. The movable carriage makes it possible to transport a lead frame for encapsulating to a mould which is at that moment available to perform the encapsulating operation. The feed means and the means for removing encapsulated product can of course also be arranged on carriages which are movable independently of each other. Any possibly non-functioning moulds of a moulding apparatus with a plurality of moulds are not used herein for encapsulating; such a moulding apparatus is hereby less susceptible to malfunction. When for instance one mould is not functioning due to a problem, it is possible to carry on production with the remaining moulds. It is also possible to adjust one or more moulds, wherein other moulds carry on production at the same time.

A preferred embodiment is characterized in that the guide length is variable by disconnecting and connecting guide parts. By varying the length it becomes possible to vary the capacity of the apparatus to changing requirements over a period of time. It is thus possible to acquire an apparatus of comparatively limited capacity to manufacture a new product and, if the product is found to be a success, to then increase the capacity of the apparatus by lengthening the guide and adding at least one extra mould.

Another preferred embodiment is characterized in that the carriage also comprises means for cleaning the mould halves. It is thus possible prior to loading of lead frames or after removal of the encapsulated products to clean the mould halves without a separate cleaning unit being required for each separate mould.

The carriage preferably co-acts with a lead frame loading unit for supplying lead frames to the carriage. Such a lead frame loading unit is then preferably equipped to take lead frames out of a cassette. Another preferred embodiment of the moulding apparatus is characterized in that the carriage preferably co-acts with an encapsulating material loading unit for supplying encapsulating material to the carriage. Using these loading units the carriage can be loaded without human labour being required for this purpose. In a preferred embodiment it is even possible to place in or against the loading unit a cassette used for transport of the lead frames, whereafter the loading unit takes the lead frames out of this cassette without further human intervention being required for this purpose. The chance of errors and the danger of damage to the lead frames is hereby limited.

Another preferred embodiment is characterized in that the carriage co-acts with a discharge unit for taking encapsulated product from the carriage. This discharge unit is preferably equipped to place the encapsulated product into a cassette. The above stated advantages of a loading unit are equally valid for a discharge unit; i.e. without human intervention and with little chance of errors or damage it is possible to remove the encapsulated products from the carriage and, in a recommended situation, to place the products in a cassette.

The number of moulds to be served by the carriage can be increased or reduced as desired. Subject to the capacity requirement it is possible to incorporate additional moulds in the moulding apparatus or to remove moulds from the moulding apparatus in order thus to increase or decrease the maximum capacity of the moulding apparatus. A moulding apparatus can thus be adapted for instance to a growing demand for capacity. For moulding of products wherein particularly high standards apply in respect of susceptibility to malfunction of the moulding apparatus, it is also possible to place an additional one or more moulds in the moulding apparatus. If one or more moulds then cease production due to malfunction, the total moulding apparatus will still provide the required maximum capacity.

The carriage preferably also serves a device for processing encapsulated product. Due to this extra function of the carriage it is possible to couple the moulding apparatus mechanically to a follow-on process such as for instance trimming the encapsulated products and subsequent bending of the leads. It is also possible however to allow a processing of the encapsulated products to take place before they are placed in a magazine. Here can be envisaged for example a so-called degate process and/or punching process. These processes are intended to remove excess epoxy. A quite different possibility is the addition of a process for controlling the quality of the encapsulated product. In this linking of a number of processing units it is recommended to place the processing units as closely as possible to each other. Transporting distances are hereby minimized, whereby the required transport time is also minimized. It is however possible in specific situations to place the processing units further apart; the guide along which the carriage moves will hereby be extra-long. The advantages of a fixed sequence of different production processes can thus be realized in comparatively very simple manner using this invention. It is also possible to provide with extra functionality an unloading or loading unit situated on a carriage.

The present invention will be further elucidated with reference to the non-limitative embodiments shown in the following figures, wherein:

• fig. 1 shows a perspective view of a moulding apparatus according to the present invention without carriage;
• fig. 2 shows a partly cut away perspective view of a part of the apparatus shown in fig. 1 with carriage;
• fig. 3 shows a perspective view of a partly cut away mould and a carriage illustrated separately; and
• fig. 4 shows a top view of an alternative embodiment of the moulding apparatus according to the invention.

Fig. 1 shows a moulding apparatus 1 with a loading unit 2, two mould units 3, 4 and a discharge unit 5. A carriage not shown in this figure is movable along a guide 6 by engagement of for instance a toothed wheel on a toothed path 7. A cassette 8 in which lead frames 9 are arranged is placed against the loading unit 2. Lead frames 9 are supplied as according to arrows P1 to a carriage when this latter is situated at a position adjacently of cassette 8. An encapsulating material feed device 10 is disposed above the guide 6 to place pellets of encapsulating material 11 on the carriage so that the latter can transport them further to the mould units 3, 4. After the carriage provided with pellets 11 and lead frames 9 has been displaced to one of the mould units 3, 4, the carriage places the lead frames 9 and pellets 11 between the mould halves 12, 13, respectively 14, 15. The encapsulating process then takes place, whereafter the carriage removes encapsulated products 16 from between the mould halves 12, 13, respectively 14, 15 and transports them to the discharge unit 5. In this discharge unit 5 the encapsulated product 16 is placed from the carriages into an at least partially empty cassette 17 as according to arrow P2.

Fig. 2 shows a view of a part of the moulding apparatus 1 of fig. 1. This figure also shows a carriage 18 which is displaceable along the guide 6 as according to arrow P3 in that a toothed wheel 20 driven by a drive 19 engages onto the toothed path 7. Situated on carriage 18 are two carriers 21, 22 displaceable as according to arrow P4 relative to carriage 18. The one carrier 21 is equipped for feeding lead frames 23 and pellets of encapsulating material 24, while the other carrier 22 is equipped to discharge the encapsulated product 25. The mould unit 3 is situated in closed position, i.e. the mould halves 12, 13 are clamped against each other. The mould unit 4 on the other hand is situated in opened position, i.e. the mould halves 14, 15 are located at a mutual distance. An underside 26 of a mould is hereby clearly visible. For a further description of the operation of the mould units 3, 4, reference is made to for instance the patent publication mentioned in the preamble. The carrier 21 is also provided with cleaning means 27 with which the mould halves can be cleaned after an encapsulating operation has taken place.

Fig. 3 shows the carriage 18 without lead frames or encapsulated products. It can hereby be seen more clearly than in the foregoing figure that the carriers 21, 22 are displaceable along guides 28 in a manner such that they can be situated wholly between mould halves 12, 13.

Finally, fig. 4 shows a schematic top view of an alternatively embodied moulding apparatus 29. The mould units 3, 4 correspond with the foregoing figures but a loading unit 30 and a discharge unit 31 differ from that already shown. Grippers 34, 35 displaceable along guides 32, 33 are accommodated in loading unit 30 and discharge unit 31. These grippers 34, 35 co-act with cassettes 36, 37 respectively. The change relative to the moulding apparatus 1 shown in the foregoing figures is therefore that the carriage 18 does not co-act directly with cassettes 36, 37 but that grippers displaceable between both of these are arranged. This may have the advantage for instance that co-action can take place between cassettes 36, 37 of a variety of sizes.

Claims (10)

1. Apparatus for moulding lead frames comprising at least one mould formed by two mould halves movable relative to one another, means for introducing a lead frame into one of the mould halves, means for carrying encapsulating material into the cavities of the mould, means for exerting pressure in these cavities, means for heating the mould halves, means for cleaning the mould halves and means for removing an encapsulated product from the mould, wherein the means for introducing a lead frame into one of the mould halves, the means for carrying encapsulating material into the cavities of the mould and the means for removing an encapsulated product from the mould are arranged on at least one carriage movable along a guide relative to the mould halves, which carriage provided with means serves at least one mould.
2. Moulding apparatus as claimed in claim 1, characterized in that the guide length is variable by disconnecting and connecting on guide parts.
3. Moulding apparatus as claimed in claim 1 or 2, characterized in that the carriage also comprises means for cleaning the mould halves.
4. Moulding apparatus as claimed in claim 1, 2 or 3, characterized in that the carriage co-acts with a lead frame loading unit for supplying lead frames to the carriage.
5. Moulding apparatus as claimed in claim 4, characterized in that the lead frame loading unit is equipped to take lead frames out of a cassette.
6. Moulding apparatus as claimed in any of the foregoing claims, characterized in that the carriage co-acts with an encapsulating material loading unit for supplying encapsulating material to the carriage.
7. Moulding apparatus as claimed in any of the foregoing claims, characterized in that the carriage co-acts with a discharge unit for taking encapsulated product from the carriage.
8. Moulding apparatus as claimed in claim 7, characterized in that the discharge unit is equipped to place the encapsulated product into a cassette.
9. Moulding apparatus as claimed in any of the foregoing claims, characterized in that the number of moulds to be served by the carriage can be increased or reduced as desired.
10. Moulding apparatus as claimed in any of the foregoing claims, characterized in that the carriage also serves an apparatus for processing encapsulated product.