Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2002-01-30
2004-03-09
Thompson, Gregory D. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C165S080300, C165S185000, C361S704000, C361S710000, C361S715000
Reexamination Certificate
active
06704203
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a power supply module, in particularly, to a synchronous type DC-DC converter.
In electronic consumers for such a power supply module, the tendency is toward increasingly lower supply voltages, particularly less than 3.3 volts (today, for example, DC supply voltages commonly range from 1.2 to 1.8 volts). Generic power supply modules generate such supply voltages stably and with low noise level from input voltages ranging from 40 to 60 volts.
Since the power requirement of high-performance processors continues to increase while their supply voltage simultaneously decreases (to obtain higher clock frequencies), the required operating currents increase more than proportionally. For supply voltages of 1.2 to 1.8 volts, the output currents to be generated by common power supply modules accordingly are in the range of 60 amperes and higher. This is true particularly in connection with so-called DPAs (Distributed Power Architectures).
Due to the given high current and power densities it has thus far been necessary to provide a plurality of DC-DC converters to master these demanding power supply problems. Besides the necessary production and circuit engineering complexity, this involves the additional disadvantage of comparatively large, voluminous enclosures for the power supply modules. This creates space problems particularly in tight application environments.
It is known in the art to use a printed circuit board with a plurality of conductor layers (a so-called multilayer board) to construct DC-DC converters. This multilayer board is equipped with corresponding power semiconductors and designed to receive cores for planar inductors through corresponding openings. To cool the inductors as well as the power semiconductors, a cooling element is associated with the multilayer board as the carrier element. This creates a comparatively compact, thermally and electrically suitable arrangement. Such a device is known, for example, from the applicant's German Application 197 40 283.6.
However, this known arrangement, too, has drawbacks in view of the continuously increasing current and power densities and an intended further increase in the packaging density (while decreasing the enclosure dimensions). For, due to the employed multilayer printed circuit board material, even with up to 12 individual conductor layers of a typical layer thickness of 100 micrometers, the physically realizable limit for a maximum output current to be produced is about 60 amperes. A further increase in the output current would require track conductor geometries that can no longer be reasonably implemented in conventional enclosure sizes or printed circuit board dimensions.
From the aforementioned generic state of the art it is furthermore known to use a cooling element (typically made of aluminum) to cool simultaneously a core of an inductor as well as a power semiconductor. However, particularly with a further increase in the component or packaging density of such a device, the heat dissipation known from DE 197 40 283.6 is also no longer sufficient.
Finally, the known converter devices have the problem that the high output current must also be reliably discharged. Existing pin or port connections are not sufficient, however, especially in view of simple (preferably automated) component mounting and production as well as in view of the amperages that are expected to be obtained.
All approaches are further characterized by the technological challenge of simplifying the process technology involved in manufacturing a known power supply module. The goal is to be able to use automated component mounting and soldering processes to the largest possible extent.
OBJECTS OF THE INVENTION
Thus one object of the present invention is to improve a generic power supply module both in view of further increasing the generated output current (with correspondingly lower output voltages) and to improve heat dissipation or cooling of the electronic components (and thus to create the conditions for further integration) and to expand the possibilities for reliably discharging high currents.
Another object of the present invention is to provide a power supply module which is better suited for automated production and thus cost reduction in the production process.
SUMMARY OF THE INVENTION
The bridge element provided, according to one form of the invention, advantageously allows an elegant solution from a production and functional point of view to the problem of high current density, particularly between the output-side contact arrangement and the synchronous power semiconductors. Particularly by specifying a suitable cross section of the preferably used copper material, it is possible to process the required high output currents without significant heating. At the same time the bridge element can be treated and processed like a normal device capable of being assembled and soldered in an automated production process (e.g., an SMD electronic component). This saves additional assembly and connection costs, and the device according to the invention, and thus the entire unit, can be automatically and efficiently produced by means of conventional component mounting and soldering equipment. The 1.5 mm
2
lower limit cross section indicated in the main claim should be understood only as an example. To be usable at all, a bridge element according to the invention, compared to a copper track conductor (typically 150 micrometers thick), must permit a certain improvement with respect to power dissipation, this in relation to a conductor length suitable for automatic component insertion, which is typically between 5 and 10 mm. The present invention, however, also covers particularly those conductor cross sections for the inventive bridge element, which based on other material parameters, permit a significant drop in the power dissipation (i.e. higher by a factor of at least 4 to 5).
Advantageously, thermal relief of the carrier element, which is typically designed as a multilayer board, is also provided, so that the requirements to be met by the employed material are reduced and additional savings may possibly be realized.
According to a preferred embodiment of the invention, the inventive bridge element is a SMD, i.e., it is mounted on the surface. A further development proposes to provide positioning projections in the form of positioning segments on the bridge element, which allow simpler and more precise placement of the element in the desired position on the component side of the carrier element.
Particularly preferably, the inventive bridge element is guided on the component side in the form of a long angled strip, such that the space (available in any case) between other electronic elements or inductive components on the carrier element can be used. This embodiment makes it possible, in particular, to guide the bridge element closely to the corresponding connecting branches of the synchronous power semiconductor so as to make contact and thereby reduce transfer resistances.
In addition, the recess in the bridge element, which is provided on the component side according to a further development, makes it possible effectively to prevent any risk of a short circuit or an unintended contact with a track conductor provided on the surface of the carrier element.
The present invention thus provides an unconventional, highly flexible, easy-to-mount and reliable solution to the dilemma of continuously increasing output currents and the requirement for increasingly compact devices in that the high current conductor on the output side is conceived as a component (capable of automated mounting and assembly) instead of using the track conductors, which are available in the multilayer board but are limited by the effective conductor cross section. The strip form of the bridge element, which can be given almost any shape by angles, permits a flexible use of gaps or free areas that exist in any case on the component side of the carrier element. This provides an elegant solution to the goal o
Chapuis Alain
Gammenthaler Peter
Carter Schnedler & Monteith
Power-One A.G.
Thompson Gregory D.
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