Package for multiple high power electrical components

Details Package for multiple high power electrical components Package for multiple high power electrical components

1993-04-22

2001-09-18

Potter, Roy (Department: 2822)

Active solid-state devices (e.g., transistors, solid-state diode

Housing or package

With contact or lead

C257S723000, C257S725000

Reexamination Certificate

active

06291878

ABSTRACT:

TECHNICAL FIELD
The present invention relates generally to electrical component packages, and more particularly to a package for housing multiple high power electrical components.
BACKGROUND ART
There is a need, particularly in aircraft and aerospace installations, for compact and light weight power systems. Such power systems typically include a power converter that utilizes multiple high power switches having very high voltage and current ratings. Such power switches handle substantial amounts of power and thus dissipate heat which can adversely affect the performance of the switches and other electrical components in the vicinity thereof. The need to reduce system size and weight, however, greatly complicates the removal of such heat.
In addition, there is often a need to connect devices in parallel to obtain the required current handling capability. In order to maintain proper load sharing between parallel connected devices, lead lengths must be accurately controlled and kept as short as possible.
The foregoing considerations militate in favor of the incorporation of multiple high power components within a single package. In this way, compact assemblies that can withstand the high voltage and current levels required for proper operation can be fabricated in a small volume.
Typically, the package cannot be tested for operability until it is fully assembled. This fact creates a substantial probability that a faulty package will be produced since the incorporation of only one faulty switch into a package will render the entire package defective. This is undesirable, particularly in light of the fact that it may prove uneconomical to replace a faulty switch after it has been assembled in a package, thereby resulting in waste of operable components.
SUMMARY OF THE INVENTION
A semiconductor package according to one aspect of the present invention includes a plurality of semiconductors which are arranged in the package in an advantageous manner.
More particularly, in accordance with one aspect of the present invention, a semiconductor package includes an electrically conductive package support member having a central aperture therethrough, a central electrode structure extending through the central aperture of the package support member and electrically isolated therefrom and a plurality of semiconductor devices disposed on the package support member in an array surrounding the central electrode structure. Each semiconductor device includes first and second electrodes wherein the first electrodes of the semiconductor devices are electrically interconnected by the package support member. A first terminal is electrically connected to the package support member. The central electrode structure includes a bus for electrically interconnecting the second electrodes of the semiconductor devices and a second terminal is coupled to the bus.
Preferably, each semiconductor device is disposed on an associated device support structure having a base plate electrically interconnecting the first electrode to the package support member. Means are provided for electrically coupling the second electrode of the semiconductor device to the bus of the central electrode structure. Also in accordance with the preferred embodiment, the coupling means comprises a strip of conductive material disposed on corrugated fin stock.
Still further in accordance with the preferred embodiment, a heat exchanger is disposed in thermal contact with the semiconductor devices wherein the heat exchanger includes a base housing joined to the package support member and defines an enclosure and means disposed in the enclosure in contact with the package support member for conducting cooling fluid.
In accordance with a highly preferred form of the invention, each semiconductor comprises a power transistor and the first and second electrodes comprise main current path electrodes of the transistors. Currents flow through the package support member into the first electrodes and flow out of the second electrodes, the bus and the second terminal.
Also in accordance with this form of the present invention, each semiconductor includes a control electrode and the package further includes an additional bus for interconnecting the control electrodes.
In accordance with another aspect of the present invention, a method of fabricating a semiconductor package includes the steps of assembling each of a plurality of semiconductor devices on an associated device support structure wherein each semiconductor device has a first electrode electrically connected to an electrically conductive base plate of the device support structure and a second electrode and testing the semiconductor devices after such devices have been assembled on the associated support structures to determine which are operable. The method further includes the step of providing a package support member having an electrically conductive support surface and a central aperture therethrough. The base plates of those device support structures carrying the semiconductor devices determined to be operable are electrically and mechanically coupled to the support surface so that the first electrodes of the devices are interconnected by the support surface and so that the semiconductor devices form an array surrounding the central aperture. A first terminal is connected to the support surface and a central electrode structure is provided having a bus and a second terminal electrically connected to the bus. The central electrode structure is mechanically secured to the package support member such that the former extends through the central aperture and is electrically isolated from the package support member. Further, the second electrodes of the semiconductors are electrically connected to the bus of the central electrode structure.
Each semiconductor device preferably further includes a third electrode and the central electrode structure further includes an additional bus and a third terminal electrically connected to the additional bus wherein the third electrodes of the semiconductors are electrically connected to the additional bus.
The method of this aspect of the present invention may include the further step of securing a heat exchanger to the package support member so that the heat exchanger is in thermal contact with the semiconductor devices. The step of securing preferably includes the step of attaching fin stock segments to a lower surface of the package support member opposite the support surface. The fin stock segments are preferably enclosed and cooling fluid is provided to the enclosed fin stock segments.
A semiconductor package constructed in accordance with the present invention does not encounter the disadvantages of the prior art since the subassemblies mounted within the package may be separately tested before incorporation therein. Thus, waste is held to a minimum. Also, the semiconductor devices are cooled in an efficient fashion and occupy only a small amount of volume, thus rendering the package particularly suitable for aircraft and aerospace installations.


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patent: 4574299 (1986-03-01), Glascock, II et al.
patent: 4614964 (1986-09-01), Sutrina
patent: 4639760 (1987-01-01), Granberg et al.
patent: 4649416 (1987-03-01), Borkowski et al.
patent: 4675785 (1987-06-01), Young
patent: 4766481 (1988-08-01), Gobrecht et al.
patent: 4878106 (1989-10-01), Sachs

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