Optoelectronic semiconductor component

1. Field of the Invention

The present invention relates to a radiation-emitting and/or radiation-receiving semiconductor component in which a radiation-emitting and/or radiation-receiving semiconductor chip, is secured on a chip carrier part of a lead frame wherein the semiconductor chip and at least a partial region of the chip carrier part are surrounded by an encapsulation.

2. Description of the Prior Art

Such a semiconductor component is disclosed, for example, in European Patent Application EP 400 176. The latter describes a so-called top LED, in which a semiconductor chip is secured on a planar chip carrier part of a lead frame. The lead frame is composed of the chip carrier part and a connection part, arranged separately from the latter, with a respective external connection. The chip carrier part includes the semiconductor chip. The connection part and partial regions of the external connections are surrounded by a encapsulation which comprises a radiation-impermeable base body having a recess and a radiation-permeable window part which fills up this recess. This chip carrier part and the connection part are surrounded by the base body, or embedded in the latter, in such a way that partial regions of the upper sides of the chip carrier part and of the connection part are flush with the remaining bottom surface of the recess. Except for its underside, by which it rests on the chip carrier part, the semiconductor chip is completely surrounded by the radiation-permable window part. The recess, which is completely filled up by the radiation-permeable window part, is fashioned in such a way that it forms a reflector for the radiation emitted by the semiconductor component.

The present invention is directed to developing a radiation-emitting and/or radiation-receiving semiconductor component of the type mentioned in the introduction in such a way that it has an increased radiant intensity and can be produced in a simple manner. At the same time, this semiconductor component is to have good heat dissipation from the semiconductor chip.

In an embodiment of the present invention, the chip carrier part forms a trough in the region in which the semiconductor chip is secured. The inner surface of the trough is designed in such a way that it forms a reflector for the radiation which is emitted and/or received by the semiconductor chip. The chip carrier part has at least two external electrical connections which project from the encapsulation at various points thereof.

In an embodiment the chip carrier part forms a trough in the region in which the semiconductor chip is secured. The inner surface of the trough is designed in such a way that it forms a reflector for the radiation which is emitted and/or received by the semiconductor chip. The trough of the chip carrier part projects at least partially from the encapsulation in such a way that the chip carrier part can be electrically and/or thermally connected in the region of the trough.

In an embodiment, the lead frame has the chip carrier part and a connection part, arranged at a distance from the chip carrier part, with two external connections which project from the encapsulation at opposite sides.

In an embodiment, at least some of the inner surfaces of the trough of the chip carrier are coated with a reflection-enhancing material.

In an embodiment, the external connections of the chip carrier part are broader than the external connections of the connection part.

In an embodiment, the encapsulation has a radiation-impermeable base body with a recess and a radiation-permeable window part which is arranged in the recess. The radiation-impermeable base body encapsulates at least a partial region of the chip carrier part in such a way that at least the trough of the chip carrier part is arranged in the recess.

In an embodiment, the upper edge of the trough extends below the upper edge of the recess. The partial region of the inner surface of the recess which is not covered by the trough is designed in such a way that it forms a reflector for the radiation emitted by the semiconductor chip.

In an embodiment, some of the inner surfaces of the recess of the radiation-impermeable base body are coated with a reflection-enhancing material.

Additional features and advantages of the present invention are described in, and will be apparent from, the Detailed Description of the Presently Preferred Embodiments and from the Drawings.

FIG. 1 a shows a plan view of an embodiment of a semiconductor component in accordance with the present invention.

FIG. 1 b shows a cross-sectional view of the semiconductor component shown in FIG. 1 a taken along the line A—A.

FIG. 1 c shows a cross-sectional view of the semiconductor component shown in FIG. 1 a taken along the line B—B.

FIG. 2 a shows a plan view of another embodiment of the semiconductor component of the present invention.

FIG. 2 b shows a cross-sectional view of the semiconductor component shown in FIG. 2 a taken along the line C—C.

FIG. 3 shows a sectional view through another embodiment of the semiconductor component in accordance with the present invention.

The semiconductor component of FIGS. 1 a to 1 c is a so-called top LED which is constructed as a surface-mounted device. It is composed of a metallic lead frame, comprising a chip carrier part 2 , a connection part 10 two external connections 11 , 12 , a radiation-emitting semiconductor chip 1 secured on the chip carrier part 2 , and a parallelepipedal encapsulation 3 . The semiconductor chip 1 has a respective contact metallization layer 16 , 17 on its top side and on its underside, respectively. The contact metallization layer 17 on the underside is electrically conductively connected to the chip carrier part 2 , for example by means of a metallic solder or an electrically conductive adhesive, and the contact metallization layer 16 on the top side is electrically conductively connected to the connection part 10 by means of a bonding wire 20 , which is composed, for example, of gold or another suitable metallic material. A trough 4 is formed, for example, by means of embossing, in that region of the chip carrier part 2 in which the semiconductor chip 1 is secured, the inner surface 5 of the trough has the approximate shape of an upside-down truncated cone and forms a reflector for the radiation emitted by the semiconductor chip 1 . The external connections 11 , 12 of the chip carrier part 2 and of the connection part 10 each project from this encapsulation 3 on opposite sides and are bent outside the encapsulation 3 , downwards and then inwards towards the centre of the encapsulation 3 . However, they can also have any other desired form.

The encapsulation 3 is produced in two parts from a radiation-impermeable base body 7 having a recess 8 and a radiation-permeable window part 9 which fills up this recess 8 . The base body 7 and the window part 9 are composed, for example, of a filled synthetic resin or of a thermoplastic and, respectively, of a transparent synthetic resin or polycarbonate. Suitable fillers for synthetic resin are, for example, metal powders, metal oxides, metal carbonates or metal silicates. The chip carrier part 2 and the connection part 10 are surrounded by the radiation-impermeable base body 7 , or embedded in the latter, in such a way that a partial region of the connection part 10 and at least that partial region of the chip carrier part 2 in which the trough 4 is situated rest on the bottom surface 19 of the recess 8 . The recess 8 has a larger depth than the trough 4 , with the result being the trough 4 is arranged completely within the recess 8 and the inner surface 13 of the said recess projects upwards beyond the trough 4 .

In a preferred embodiment, the inner surface of the trough 4 and possibly also that part of the top side of the connection part 10 which adjoins the window part 9 , are polished or coated with a reflection-enhancing material for the purpose of improving the reflection. A suitable reflection-enhancing material is, for example, a lustrous lacquer or aluminum, which is vapour-deposited, sputtered on or applied by means of another suitable method. Equally, those regions of the inner surface 13 which are not covered by the chip carrier part 2 and connection part 10 can also be provided with a reflection-enhancing layer. As a result, these regions, too, reflect the radiation, emitted by the semiconductor chip 1 in the intended main radiation direction 6 . A lustrous lacquer or aluminum is once again suitable for this purpose and may be applied by the methods mentioned above.

It would also be conceivable for the recess 8 not to be completely filled up by the window part 9 , but instead for only the semiconductor chip 1 and the trough 4 or any other desired partial region of the recess 8 to be surrounded or covered by the window part. Equally, the window part 9 can be produced in such a way that it projects beyond the upper edge of the recess 8 .

In order to improve the heat dissipation from the semiconductor chip 1 , it is possible, as shown in FIGS. 2 a and 2 b, for the external connections 11 of the chip carrier part 2 to be broader than the external connections 12 of the connection part 10 . Though not shown, such may also be possible with respect to the embodiments shown in FIGS. 1 a - 1 c . Equally, if necessary or possible, just one external connection 11 or a plurality (>2) of external connections 11 can be routed out of the encapsulation from the chip carrier part 2 . The same applies to the connection part 10 .

In a method for producing the inventive semiconductor component according to the first exemplary embodiment, it is possible, if the base body 7 is composed of a thermoplastic or another temperature-resistant material, for the lead frame to be encapsulated with the base body material, and for the semiconductor chip and the bonding, wire to be secured. Further, recess 8 may be filled with the material of the window part 9 .

The second exemplary embodiment shown in FIGS. 2 a and 2 b differs from the first exemplary embodiment only by the fact that the chip carrier part 2 is embedded in the base body 7 in such a way that the bottom wall 18 of the trough 4 projects from the base body on the underside thereof. As a result, it is possible to make direct external contact with the chip carrier part 2 , for example, by bonding or soldering it directly to a printed circuit board. Furthermore, in this exemplary embodiment the external connections 11 of the chip carrier part 2 have a greater width than the external connections 12 of the connection part 10 . These measures, individually or in combination, ensure improved heat dissipation from the semiconductor chip 1 .

All of the developments and refinements of the semiconductor component according to the invention which have been cited above with regard to the first exemplary embodiment can also be realized in the case of the second exemplary embodiment.

The third exemplary embodiment according to FIG. 3 differs from the aforementioned first exemplary embodiment by the fact that the encapsulation 3 is, produced completely from a radiation-permeable material for example, a transparent synthetic resin. In this case, too, all of the refinements cited in connection with the first exemplary embodiment are conceivable.

The fourth exemplary embodiment has all of the features of the second exemplary embodiment except for that the encapsulation is produced completely from a transparent material.

The above-described embodiments and exemplary embodiments of the semiconductor component according to the invention are not just restricted to the use of a radiation-emitting semiconductor chip 1 , but also can be used for photodiode, phototransistor and other radiation-receiving semiconductor chips. The trough 4 is in this case designed in such a way that the radiation which is incident through the window part 9 is reflected in the direction of the semiconductor chip.

Although the present invention has been described with reference to specific embodiments, those of skill in the art will recognize that changes may be made thereto without departing from the spirit and scope of the invention as set forth in the hereafter appended claims.