Electric power conversion systems – Current conversion – With conductive support mounting
Reexamination Certificate
2000-01-31
2001-04-03
Wong, Peter S. (Department: 2838)
Electric power conversion systems
Current conversion
With conductive support mounting
C361S707000, C361S715000
Reexamination Certificate
active
06212087
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electronic bridge module, specifically to a high power metal oxide semiconductor half bridge module for an internal combustion engine starter/alternator circuit in which the module has a very low inductance.
Starting an internal combustion engine and rectifying the voltage generated by an alternator once the engine is running places high demands on the electronic circuitry required to support these functions. A typical starter/alternator requires minimum voltage drop at its input and an immediate torque current to mechanically “crank” the engine. In order to minimize voltage drop and supply immediate current, the start/alternator circuit path must have a low resistance and an extremely fast current slew rate (di/dt). The circuit must perform these functions under extreme temperature conditions such as might be found in a typical automotive environment. For example, the circuit must be capable of supplying a 650 amp current at −25° C. in a 42 volt system such that the current slew rate is faster than 1500 amps per microsecond.
An essential component of the starter/alternator circuit is a half bridge rectifier. The half bridge rectifier must be capable of supporting the characteristics described above. A typical half bridge rectifier is produced as a module employing metal oxide field effect transistor (MOSFET) devices. In order to achieve the desired performance characteristics and avoid device overvoltage and avalanche conditions, the low voltage silicon used in the MOSFET devices must provide a resistance path of less than 2 milliohms at 25° C., and a maximum module inductance of 12 nH. Of course, the module must be of a size small enough to be mounted at a spot convenient to its placement within the starter/alternator circuit, typically as part of a bus bar assembly located in a motor vehicle's engine compartment.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a high power half bridge module for a starter/alternator circuit in which the module is small, has a very low inductance, and can support the power requirements needed to start an internal combustion engine in a wide temperature range.
The present invention provides a rectifying module in which there is a thermally conductive base. A plurality of lower circuit boards are adjacently positioned within the thermally conductive base along a same plane. At least one semiconductor device has a first surface, the first surface of the semiconductor device is mounted to one of the plurality of lower circuit boards. A common terminal has a planar portion in which the planar portion is coupled to each of the plurality of lower circuit boards. An upper circuit board is in electrical contact with the plurality of lower circuit boards in which the upper circuit board includes a connector providing external access for drive signals for the semiconductor device.
Another aspect of the module of present invention further includes at least one contact pin. The contact pin is used to provide the electrical contact between the upper circuit board and one of the plurality of lower circuit boards.
As another aspect of the module of present invention, the contact pin includes a curved portion to form a resilient contact.
As still another aspect, the module of present invention further comprises two voltage terminals in which each of the two voltage terminals are coupled to a different one of the plurality of the lower circuit boards.
Another aspect of the module of present invention provides that the two voltage terminals extend from the plurality of lower circuit boards at differing distances.
As still yet another aspect of the module of present invention, the at least one semiconductor device further includes a second surface located opposite the first surface in which the second surface is coupled to one of the plurality of lower circuit boards by at least one wire bond.
As another aspect of the module of present invention, the at least one wire bond is “S”-shaped such that an attachment point on the one lower circuit board is angularly displaced from an attachment point on the second surface.
Another aspect of the present invention provides a module in which the at least one semiconductor device is a MOSFET device and the attachment point of the second surface is a source region.
As another aspect of the present invention, the module forms a half bridge rectifier.
As a further aspect of the present invention, the module is implemented in a 42 volt internal combustion engine starter/alternator circuit.
The present invention provides, as still another aspect, that the total package inductance of the module is less than approximately 8.4 nanoHenries.
As a further aspect of the module of the present invention, one of the voltage terminals is a negative terminal and the module further comprises a resistor and capacitor connected in a parallel arrangement between the negative terminal and the common terminal.
Another aspect of the invention provides that, the total thickness of the module is less than approximately 0.75 inches.
The present invention also provides a half bridge rectifying module for use in an internal combustion engine starting/alternator circuit, in which the module has a thermally conductive base. A plurality of lower circuit boards are adjacently positioned within the thermally conductive base along a same plane. At least one MOSFET semiconductor device has a first surface, the first surface of the MOSFET semiconductor device is mounted to one of the plurality of lower circuit boards. A common terminal has a planar portion coupled to each of the plurality of lower circuit boards. An upper circuit board is in electrical contact with the plurality of lower circuit boards and includes a connector providing external access for drive signals for the MOSFET semiconductor device.
As still another aspect, the present invention provides a rectifying module in which there is a thermally conductive base. A lower circuit board is positioned within the thermally conductive base. At least one MOSFET semiconductor device has a first surface, which is a drain surface, mounted to the lower circuit board, and a second surface opposite the first surface which is coupled to the lower circuit board by at least one “S”-shaped wire bond, in which the attachment point on the lower circuit board is angularly displaced from an attachment point on the second surface. A common terminal has a planar portion, the planar portion is coupled to the lower circuit board. A plurality of voltage terminals are coupled to the lower circuit board and extend at different distances therefrom. An upper circuit board is in electrical contact with the lower circuit board, the upper circuit board includes a connector providing external access for drive signals for the MOSFET semiconductor device.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
REFERENCES:
patent: 6031730 (2000-02-01), Kroske
patent: 6078501 (2000-06-01), Catrambone et al.
Grant William
Polack Joshua
International Rectifier Corp.
Laxton Gary L.
Ostrolenk Faber Gerb & Soffen, LLP
Wong Peter S.
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