In the moulding with plastic of a lead frame and chip

-V arranged thereon, liquid plastic is supplied through a runner to a mould cavity. The edge zones of the frame are herein clamped between both the mould halves movable 5 relative to each other and enclosing the mould cavity. In the case of very dense packing it is desirable to supply the liquid plastic in the runner on either side of the lead frame, which is achieved by arranging a passage opening in the edge portion of the lead frame protruding into the 10 runner.

Such a method is known from the Netherlands patent application 90.02477.

After the moulding the moulded lead frame has to undergo an after-processing wherein portions of the lead 15 frame are cut through in a punching operation. The leads are also bent. These operations are known as trimming and shaping operations.

The known cutting tools cannot be used without problem in the case of lead frames moulded by double gating 20 according to patent application 90.02477.

The gate corner of the lead frame placed in the runner for liquid plastic must undergo an operation other than the usual trimming and shaping operation.

The invention provides a solution herefor. This is 25 achieved with a tool for a device for cutting through with a punching operation the gate portion of a lead frame with chip which is encapsulated with plastic by supplying liquid plastic through a runner, wherein an edge portion of the lead frame provided with an opening protrudes into the 30 runner such that the plastic is supplied on either side of the lead frame, which tool has a C-shaped form, whereof each of the legs has a polygonal cross section (figure 3) .

With a tool according to the invention the fitting portions are cut away during the operational cycle.

The invention will be further elucidated with reference to the drawings.

Figure 1 shows in perspective view a mutually connected series of lead frames encapsulated in the above described manner, figure 2 is a view corresponding with figure 1 having designated therein the tool according to the invention, and figure 3 is a perspective view relating to the situation after the cutting operation. The lead frame consists as is usual of a central portion onto which is placed a chip, the connecting points of which are connected using gold wiring to the fitting strip-like conductors of the lead frame leading to the outside. The lead frame is subsequently moulded with plastic and takes the form as indicated in figure 1. On the gate corner 1 is shown the shape of the portions 2, 3 for machining.

As can be seen in figure 2, the tool 4 takes the form of a double-C, whereof the legs 5 and 6 have an identical shape and are polygonal in cross section.

In figure 2 the machining contours of the tool 4 are shown with broken lines. After a punch-like cutting operation the material present within the line border is cut or punched out (as shown in figure 3) . In addition a further operation takes place similar to the known trimming and shaping operation and which consists of cutting through leads and dam bars.

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