Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-06-19
2002-10-22
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S403000, C524S413000, C524S428000, C524S430000, C428S457000
Reexamination Certificate
active
06469086
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to plastic composite bodies such as electrical components which have a body of a semiconductor material, for example a microchip.
It has been known to attach microchips by a layer of chip-attaching adhesive onto conductive supporting frames, which are known as lead frames. These lead frames are then attached by means of conductive adhesive or by soldering to conductor tracks on a printed-circuit board.
In the case of plastic composite bodies such as in the case of semiconductor devices which have a basic body of metal, such as a lead frame for example, and a body of semiconductor material, such as a microchip for example, undesired failures often occur under actual environmental conditions. This is also attributed to inadequate heat dissipation from the microchip.
U.S. Pat. No. 5,037,876 (European published patent application EP 0 394 767) discloses a plastic molding compound which has a plastic material and a filler. The filler contains nanoscale particles.
Patent Abstracts of Japan vol. 097, no. 007, Jul. 31, 1997 discloses a plastic molding compound. The plastic molding compound has a filler and a plastic material. The filler contains nanoscale particles. In addition, the document discloses a composite body which comprises a basic body and a chip attached on the basic body by means of a layer of adhesive. The layer of adhesive has a filler and a plastic material, with the filler containing ceramic nanoscale particles.
U.S. Pat. Nos. 5,907,190 and 5,989,942 (European published patent application EP 0 714 125) disclose a plastic molding compound which has a filler and a plastic material. The filler contains nanoscale particles. Particle sizes of 10 nm and 100 nm are specified.
SUMMARY OF THE INVENTION
The object of the invention is to provide a plastic composite body which overcomes the deficiencies and disadvantages of the prior art devices and methods of this kind, and which ensure reliable operation even under high thermal loading.
With the above and other objects in view there is provided, in accordance with the invention, a plastic molding compound, comprising:
a proportion of at least one plastic material, in particular a thermosetting material; and
at least one filler in the plastic material, the filler having nanoscale, spherical particles produced by a condensation process.
In accordance with an added feature of the invention, the particles have a size in a range of up to 1000% a size of oligomeric compounds of the plastic material.
In accordance with an additional feature of the invention, the particles have a size in a range of up to 40 nm.
In accordance with another feature of the invention, the filler contains ceramic particles. Preferably, the particles are aluminum oxide, boron nitride, and/or aluminum nitride particles.
In accordance with a further feature of the invention, the filler contains metallic particles. Preferred metallic particles are selected from metallic particles with silver, palladium, and/or copper.
With the above and other objects in view there is also provided, in accordance with the invention, a composite body, comprising:
a basic body;
a chip of a semiconductor material mounted on the basic body;
a layer of adhesive attaching the chip on the basic body, the layer of adhesive having at least one plastic material and at least one filler with nanoscale, spherical particles produced by a condensation process.
There is further provided a filler for a plastic molding compound for the solid bonding of semiconductor bodies to other materials, such as metal, and or for sheathing semiconductor bodies with the plastic molding compound. The filler comprising nanoscale, spherical particles produced by a condensation process and dispersed in the plastic molding compound.
In accordance with a concomitant variation of the invention, there is also provided a composite body, in particular an integrated circuit, comprising:
a semiconductor chip;
a basic body of metal carrying the semiconductor chip; and
a sheathing encasing the semiconductor chip, the sheathing being formed of a plastic material and a filler in the plastic material, the filler having spherical nanoscale particles produced by a condensation process.
According to the invention, a plastic molding compound is provided, in particular for the solid bonding of semiconductor bodies to other materials such as metal and/or for sheathing semiconductor bodies. The plastic molding compound has at least one plastic material, which may be a thermosetting or a thermoplastic material, with at least one filler being incorporated in the plastic material. At the same time, the filler or at least one of the fillers, has nanoscale, in particular spherical, particles produced by a condensation process.
A new physical vaporizing technology makes it possible to produce particles which are smaller than 100 nm. The particles are produced spherically by condensation, the type of compound being determinable by the use of specific process gases. In this way, it is possible to produce oxides, nitrides etc. of a particularly small size.
Use in the plastic molding compound according to the invention leads to numerous advantages.
When used in semiconductor technology, an electrical component is protected against mechanical and chemical influences by the plastic molding compound according to the invention. In this case, a semiconductor chip is encapsulated in an injection-molding process together with its contacting assembly, for example with a lead frame, by a compression molding compound based for example on epoxy resin, under the effect of pressure and temperature. Finally, only the terminal wires are left protruding out of the housing produced in this way, and these are electroplated and bent over in order to form a finished “package” as it is known.
The plastic molding compound according to the invention can be provided with a high proportion of filler, so that only a small proportion of expensive base resin is necessary. In this case, good flow properties are advantageously provided in the molding tool, producing the advantage that the package and the terminal wires are not damaged or displaced in the injection-molding process.
When the plastic molding compound according to the invention is used, optimizing the incorporation of the filler into the compression molding compound and fine-tuning the tool design and the injection-molding parameters is made significantly easier. This is so because the particles do not represent a mechanical obstacle to the epoxy resin. As a result, the flow behavior of the compression molding compound is improved in the mold flow.
This increases the service life of the molding tool, since the gate is subjected to little wear by smaller particles. The mechanical loading of the wires and chips decreases, since the particles flow more easily around the chip, representing an obstacle. The filler content of the plastic molding compound according to the invention is increased by the use of nanospheres, resulting in a lower coefficient of thermal expansion.
The plastic molding compound according to the invention may also be used as a so-called diebonding adhesive with a high filler content, whereby a high thermal conductivity is achieved, for example for mounting power semiconductor devices on metallic lead frames. This makes it possible to dispense with mounting techniques involving more difficult process technology, such as soldering or ligation. This is because the use of nanoscale fillers allows higher proportions of filler in adhesives. Moreover, the thermal conductivity of a layer of adhesive produced with a plastic molding compound according to the invention can also be varied and specific use when there is a definite requirement concerning thermal conductivity is possible.
The size of the particles may preferably be in a range up to 1000% of the size of oligomeric compounds of the plastic material, since this results in a particularly good incorporation of the particles into a plastic material that is in the crosslinki
Atzesdorfer Alexandra
Janczek Thies
Neu Achim
Greenberg Laurence A.
Infineon - Technologies AG
Locher Ralph E.
Sanders Kriellion A.
Stemer Werner H.
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