Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor
Reexamination Certificate
2000-03-27
2001-05-29
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
C438S111000, C438S123000
Reexamination Certificate
active
06238950
ABSTRACT:
BACKGROUND OF THE INVENTION
2. Field of the Invention
The present invention relates, in general, to multi-component electronic circuits, and more specifically, to an assembly and method for assembling an integrated circuit that is tightly coupled to inductor and capacitor elements on a single leadframe.
3. Relevant Background
Many passive components (e.g., capacitors, inductors and resistors) cannot be cost effectively integrated onto a monolithic integrated circuit because of their size. Also, the limitations in a particular integrated circuit processing technology may prohibit inductors or high valued capacitors and resistors. Typically, large valued inductors and capacitors are manufactured as separate components and interconnected with the integrated circuit to provide the desired functionality.
For example, in power supplies such as AC-DC and DC-DC converters, large value inductors and capacitors are required that cannot be provided on the integrated circuit. Most such circuits are manufactured using multiple components interconnected by printed wiring on a circuit board. However, there is increasing demand for single device solutions for power supply circuits to reduce overall system size.
It is desirable from a manufacturer's and user's standpoint that packaged circuits require as few external components as possible. This eases assembly and lowers costs for the end user while increasing value added to the manufacturer. Hence, integrated circuit manufacturers are increasingly offering multi-component modules that include one or more integrated circuit chips packaged together with external passive components such as inductive and capacitor elements.
Another advantage of multi-component packaging is that stray and parasitic capacitance and inductance associated with leads and circuit board traces can be eliminated. However, stray capacitance and inductance associated with wire bonds connecting multiple chips remain a problem. In conventional multi-component modules, components are mounted on a substrate or leadframe in the same plane and coupled together by wire bonds. This “planar” arrangement results in large packages making the packages more difficult to use, expensive to manufacture and costly in terms of circuit board real estate for the user.
Some attempts have been made to vertically stack integrated circuits with associated passive components. Some of these efforts require three dimensionally formed lead frames that are difficult to manufacture and difficult to work with on an assembly line. Also, the integrated circuits could be left exposed on the surfaces of the vertical stack. Moreover, existing vertically stacked assemblies require relatively difficult assembly adding to the production cost of the component. It is desirable to use planar lead frames and to avoid exposure of the integrated circuit chip.
SUMMARY OF THE INVENTION
The present invention involves a multi-component electronic assembly including a leadframe having upper and lower surfaces and a plurality of conductive leads. The leadframe includes first bonding surfaces on the upper surface of each lead and second bonding surfaces on the lower surface of each lead. Preferably, each lead has a plurality of third bonding surfaces formed on at least some of the plurality of leads where the third bonding surfaces are formed by conductive extensions of the leads that extend towards the center of the assembly. A first component is electrically and mechanically coupled to the first bonding surfaces. A second component is electrically and mechanically coupled to the second bonding surfaces. Where third bonding surfaces are used, a third component is electrically and mechanically coupled to the third bonding surfaces.
Another aspect of the present invention is a leadframe having a plurality of leads, each lead having first, second, and third bonding surfaces and having a terminal end for coupling the first, second and third bonding surfaces to external electrical circuitry.
In another aspect the present invention involves a method for assembling a multi-component electronic assembly including the steps of providing a leadframe having upper and lower surfaces and a plurality of conductive leads. Each lead has first bonding surfaces on the upper surface of each lead and second bonding surfaces on the lower surface of each lead. Preferably, at least some of the leads include a plurality of third bonding surfaces. A first component is electrically and mechanically coupled to the first bonding surfaces. A second component is electrically and mechanically coupled to the second bonding surfaces. A third component is electrically and mechanically coupled to the third bonding surfaces.
REFERENCES:
patent: 5801072 (1998-09-01), Barber
patent: 5910010 (1999-06-01), Nishizawa et al.
patent: 5994169 (1999-11-01), Lamson et al.
patent: 6140154 (2000-10-01), Hinkle et al.
Fowler Tom L.
Howser James H.
Brady III Wade James
Jones Josetta I.
Niebling John F.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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