Patent Description:
Power electronic modules or power inverters can be designed for normal load conditions or overload conditions on vehicles. At peak load conditions, appropriate thermal management is critical. For example, as inverters deal with the peak load current, the interface between two mating conductors or contacts becomes more critical because this interface can be a bottleneck for electrical current and thermal heat flow. There is an inherent resistance at the interface which generates heat. This also hinders thermal flow used for cooling, which makes heat management difficult. To reduce electrical resistance at the contact interface, the outside envelope size of the contacts can be increased. However, this results in an inefficient use of space within the inverter. It is desired to reduce electrical resistance at the contact interface without increasing the outside envelope size of the contacts.

<CIT> discloses a switch contact formed or finished by drawing, planing, rolling, milling or polishing, and are slidably engaged with the directions of their grains aligned to ensure good electrical connection. The contact surfaces may be plated or galvanized. <CIT> discloses the preamble of independent claim <NUM>.

<CIT> is directed to connected metallic conductors which are flat and made from aluminum or aluminum-copper compounds. Oppositely-located contact surfaces are provided with grooves, indentations or the like on the conductors. During assembly, the contact surfaces are brought into direct contact, and the conductors are pressed together with such a strong force that a plastic deformation and, consequently, a metallic, electrically-conductive contact are effected at a plurality of locations at the contact surfaces. The plastic deformation effects a breaking open or splintering of oxide layers present at the contact surfaces, which exposes bare metal for producing the contact. The pressing force can be generated by tightening screws, which are led, for example, directly through the contact surfaces.

<CIT> is directed to a device for transmitting electrical energy comprising two elongated side member shaving substantially identical cross section shape, each of said members having a plurality of alternate groves and ridges extending longitudinally thereof and formed on the side therefore facing the other member, an intermediate elongated member disposed between the two side members and having alternate ridges and grooves formed on its side dace adapted and arranged to interfit with the grooves and ridges of the side members, the wall defining each groove being so shaped an angularly disposed to each other and to the walls of the ridge received within it that when the side and intermediate members are forced toward each other to cause the ridges to be fully received within the grooves a galling action takes place between the contacting walls of the grooves and ridges.

The invention is set out in the independent claim to which reference should now be made. Preferable features are set out in the dependent claims.

In <FIG> and <FIG>, an electrical connector assembly <NUM> includes an electrically conductive first contact member <NUM> and an electrically conductive second contact member <NUM>. The first contact member <NUM> includes an outer portion <NUM> and an inner portion <NUM> which is offset from the outer portion <NUM>.

The inner portion <NUM> of the first contact member <NUM> terminates in a socket <NUM>, that comprises an optional terminating end <NUM>, which may extend in a generally perpendicular direction with respect to the inner portion <NUM>. In one embodiment, the socket <NUM> is a generally hollow member for receiving conductor <NUM>. For example, the socket <NUM> has an interior recess, such as a substantially cylindrical recess, for receiving a conductor <NUM> (e.g., stripped of dielectric insulation) that is soldered, welded (e.g., welded sonically), brazed, bonded, crimped or otherwise connected. The conductor <NUM> may comprise a cable, a wire, a twisted wire or cable, a solid wire, or another suitable conductor for transmitting electrical energy.

In an alternate embodiment, the socket <NUM> the optional terminating end <NUM> may be removed or bored out such that the conductor <NUM> may extend through the socket <NUM> to be welded, soldered or otherwise mechanically and electrically connected to the (upper) surface or inner portion <NUM> of the first contact. Further, the outer portion <NUM> can be larger, such as longer and wider, to accommodate the thermal dissipation.

As illustrated and according to the invention, the outer portion <NUM> of the first contact member <NUM> has a generally triangular shape, a tear-drop shape and embodiments outside the invention may have an arrow-head shape with a rounded tip or rounded point, and other embodiments outside the scope of the invention may have different shapes. The inner portion <NUM> is connected to the outer portion <NUM> by a step or transition portion <NUM>. For example, the transition portion <NUM> provides a greater surface area for dissipating heat from one or more heat generating components of a circuit board or substrate, where the inner portion <NUM> and the outer portion <NUM> are offset in generally parallel planes with respect to each other.

The first contact member <NUM> may be attached to an end of an electrical conductor <NUM>, whereas the second contact member <NUM> may be connected or coupled to one or more heat generating components of a power inverter (not shown) or power electronics module. The conductor16 may be soldered, welded, brazed, crimped or otherwise connected to the first contact member <NUM> (e.g., at the socket <NUM>). In one embodiment, the first contact member <NUM> may have a socket <NUM> with a substantially cylindrical surface, bore. Further, an exterior of the socket <NUM> may engage or mate with a collar or sleeve <NUM> to receive or secure the conductor <NUM> and to facilitate the electrical and mechanical connection between the wire and the first contact member <NUM>.

In one embodiment, the second contact member <NUM> may be mounted to an electrically insulating substrate <NUM>, such as a circuit board. The first contact member <NUM> has a first contact, or mating, surface <NUM>, and second contact member <NUM> has a second contact, or mating, surface <NUM>. In one embodiment, the first contact surface <NUM> mates with the second contact surface <NUM> directly or indirectly via an intervening layer of solder, braze, electrically conductive fluid (e.g., electrically conductive grease) or electrically conductive adhesive (e.g., polymer or plastic matrix with metallic filler).

In certain embodiments, materials used for manufacturing could be base metal, an alloy or metals, and or composite of metals. However, it needs to be ensured that manufacturing processes and choice of materials used in manufacturing are accurate enough to achieving interlocking engagement between the first contact surface <NUM> and the second contact surface <NUM>, except where knurled surfaces are adopted for some alternate embodiments. In one embodiment, the first and second contact members <NUM> and <NUM> are preferably formed out of copper, a metal, an alloy, or an electrical grade alloy. For example, the first contact member <NUM> and second contact member <NUM> can be coated with a coating such as zinc, nickel, a zinc alloy, a nickel alloy, tin over nickel or other known possible metallic coatings or layers. The first and second contact members <NUM> and <NUM> may be machined or cast as long as the cast is accurate enough to achieving interlocking engagement between the first contact surface <NUM> and the second contact surface <NUM>. In one embodiment, the first and second contact members <NUM> and <NUM>, or the non-planar mating surfaces thereof, may be manufactured using additive or subtractive manufacturing processes such as three-dimensional printing. For example, patterns in the first contact surface <NUM> and the second contact surface <NUM> could be created by additive and subtractive manufacturing, or metal vapor deposition using raw materials such as metals, and alloys, or plastic and polymer composites with metal filler or metal particles embedded therein for suitable electrical conductivity. In one embodiment, the three dimensional printing process could use polymers or plastics with metals or conductive materials embedded therein. In other embodiments, the three dimensional printing process could use conductive graphene layers that are flexible and capable of electrical connection by a conductive adhesive. Three-dimensional printing allows creation metallic and insulating objects using one pass manufacturing methods resulting in reduction of manufacturing costs.

The connector assembly <NUM> can transfer high current electrical energy between a conductor <NUM> (e.g., cross-sectional conductor size of suitable dimension or dimensions) and a conductive trace (e.g., <NUM>) or conductor (e.g., strip, pad or otherwise) of a circuit board <NUM> or heat-generating component (e.g., semiconductor switch) in a power inverter or other power electronics. The electrical connector assembly <NUM> uses one or more of the following features: (<NUM>) nontraditional shapes of each conductor or contact member (<NUM>, <NUM>) at the circuit board transition, or where the second contact member <NUM> is mounted, or (<NUM>) increased transition surface area through non-planar interface contours, such as ridges, valleys, grooves or waves in mating surfaces of the contact members (<NUM>, <NUM>). Reducing the electrical and thermal resistances at the mating surfaces reduces the heat generation and increases the effectiveness of cooling methods.

In one embodiment, the circuit board <NUM> comprises a dielectric layer <NUM> with one or more electrically conductive traces, such as metallic trace <NUM> (in <FIG>) that overlies the dielectric layer <NUM>. The dielectric layer <NUM> may be composed of a polymer, a plastic, a polymer composite, a plastic composite, or a ceramic material. The conductive traces may be located on one or both sides of the circuit board <NUM> along with one or more heat generating elements, such as power semiconductor switches. For example, metallic trace <NUM> may be coupled to an emitter terminal or a collector of a transistor (e.g., insulated gate bi-polar junction transistor) of a power electronics module (e.g., an inverter) or a source terminal or drain terminal of a field effect transistor of a power electronics module. The metallic trace <NUM> may carry an alternating current signal of one phase of an inverter or a pulse-width modulated signal, for instance.

As best seen in <FIG> and <FIG>, a bore <NUM> extends through a dielectric layer <NUM> of the circuit board <NUM>, and the second contact member <NUM> comprises an annular pad <NUM> with optional bore <NUM>. The optional bore <NUM> is coaxially aligned with the bore <NUM>. In one embodiment, the annular pad <NUM> comprises a hollow conductive stub or metallically plated through-hole. As illustrated, the optional bore <NUM> or plated through-hole can support an electrical connection to one or more conductive traces on the bottom side of the circuit board <NUM>.

In an alternate embodiment, the optional bore <NUM> allows excess solder or excess conductive adhesive to be relieved or exhausted during the soldering or connecting of the first contact surface <NUM> with or toward the second contact surface <NUM>.

In place of soldering process, advanced manufacturing processes including vapor phase deposition of conductive materials could be used to form the first and second conductive surfaces (<NUM>, <NUM>). With use of vapor phase deposition, manufacturing defects, such as air void in metallic bonds between both surfaces, such as the first contact surface <NUM> and the second contact surface <NUM>, can be eliminated, particularly if the first contact member <NUM> and the second contact member <NUM> are electrically and mechanically joined with a fastener (e.g., <NUM>) and/or retainer (e.g., <NUM>) in an alternate embodiment (e.g., as illustrated in <FIG>).

In <FIG> and <FIG>, both the first contact surface <NUM> and the second contact surface <NUM> are non-planar surfaces or non-planar mating surface. Non-planar means ridges <NUM>, valleys <NUM>, grooves, elevations, depressions, or waves are present in the first contact surface <NUM> or the second contact surface <NUM>. Mating surfaces refers to the first contact surface <NUM> and the second contact surface <NUM>, collectively. The mating surfaces have suitable size, shape and registration for interlocking engagement of the mating surfaces, with or without an intervening solder layer, braze layer, conductive adhesive layer, or thermal grease layer. In one embodiment, as illustrated in <FIG> and <FIG>, the cross section of the first contact surface <NUM> comprises a substantially triangular cross-section or a saw-tooth cross section. Similarly, the second contact surface <NUM> comprises a substantially triangular cross-section or saw-tooth cross section.

As shown, in <FIG>, inclusive, the ridges (<NUM>, <NUM>) comprise substantially linear elevations with sloped sides, whereas valleys (<NUM>, <NUM>) between each pair of ridges (<NUM>, <NUM>) comprise substantially linear depressions with sloped sides. In one configuration, a peak height is measured from a top of each ridge (<NUM>, <NUM>) to the bottom of a corresponding valley (<NUM>, <NUM>). The first contact surface <NUM> includes a plurality of elongated first ridges <NUM> and first valleys <NUM>, where a first valley <NUM> is positioned between each adjacent pair of first ridges <NUM>. Similarly, the second contact surface <NUM> includes a plurality of elongated second ridges <NUM> and second valleys <NUM>, where a second valley <NUM> is positioned between each adjacent pair of second ridges <NUM>. As best seen in <FIG>, the first and second surfaces <NUM>, <NUM> are adjoined, connected or soldered together, directly, in a meshing position or, indirectly, by an intermediary layer <NUM> of conductive solder, braze conductive adhesive, thermal grease, or otherwise. Thus, first ridges <NUM> of first contact surface <NUM> are received by the second valleys <NUM> of the second contact surface <NUM>, and second ridges <NUM> of the second contact surface <NUM> are received by the first valleys <NUM> of the first contact surface <NUM>.

<FIG> illustrates in an alternate embodiment of a connector assembly. In <FIG>, the first contact member 12a has a non-planar first contact surface 20a and the second contact member 14a has a non-planar second contact surface 22a. The first contact surface 20a includes a plurality of elongated rounded crests 30a and rounded depressions 32a, where a depression 32a is positioned between each adjacent pair of crests 30a. Similarly, the second contact surface 22a includes a plurality of elongated rounded crests 34a and rounded depressions 36a, where a depression 36a is positioned between each adjacent pair of crests 34a. The first and second surfaces 20a and 22a can also be soldered or connected together in a meshing position by a layer of conductive solder, braze, conductive adhesive, thermal grease, or otherwise. Thus, crests 30a of first contact surface 20a are received by the depressions 36a of the second contact surface 22a, and crests 34a of the second contact surface 22a are received by the depressions 32a of the first contact surface 20a.

Referring again to <FIG>, the first contact member <NUM> has a substantially triangular shape (e.g., or a tear-drop shape) with curved corners and the second contact member <NUM> has a substantially circular, substantially elliptical or rounded surface area for thermal transfer of thermal energy from a heat-generating device (e.g., semiconductor switch) mounted on the circuit board <NUM> to one or more of the following: (<NUM>) conductor <NUM>, (<NUM>) inner portion <NUM> or step portion <NUM>, and (<NUM>) ambient air around the conductor <NUM>, the inner portion <NUM>, or the step portion <NUM> (e.g., rise portion). In alternate embodiments, the shape of the contact members (<NUM>, <NUM>) can vary from those illustrated in <FIG>, inclusive. The contacts can be funnel-shaped or circular to provide a smooth transition. The contacts could also be diamond or oval-shaped. The interface surfaces <NUM> and <NUM> can be a variety of three-dimensional (3D) or non-planar surfaces as long as they increase the surface area of the interface, such as V shaped, diamond, waffle, wave, knurled or tetrahedral. For a knurled surface (not shown), alignment may not be important as with the ridges.

The contacts can be bonded together by a variety of means, such as solder, braze, conductive adhesive, cold-press, and bolting (e.g., with conductive grease). Such interfaces could be applied to a circuit-board-style connection (as illustrated in <FIG>) or to a bus-bar connection (e.g., with a bus-bar of metal or alloy with a substantially rectangular cross-section or substantially polyhedral cross-section).

Thus, this connector assembly <NUM> transfers heat away from heat-generating electrical or electronic components on the circuit board or substrate <NUM>. A thermal flow path is supported from the heat-generating component on the circuit board <NUM> via one or more conductive traces <NUM> to the second contact member <NUM> on the circuit board <NUM> and then to the first contact member <NUM> that is connected to the conductor <NUM>. The interface surfaces (<NUM> and <NUM> or 20a and 22a) facilitate efficient heat transfer from the second contact member (<NUM> or 14a) to the first contact member (<NUM> or 12a) and to the cable or conductor <NUM> connected to it, which can dissipate the heat to the ambient air. The step <NUM> in the first contact member <NUM> helps to direct the heat away from the circuit board <NUM> or substrate. Because of the overall teardrop, curved or rounded triangular shape of the contact members <NUM> and <NUM>, the heat tends to be directed/channeled toward the first contact member <NUM> which is attached to the conductor <NUM>.

<FIG> is an exploded perspective view an alternate embodiment of an electrical connector assembly <NUM> in accordance with the disclosure. The electrical connector assembly <NUM> of <FIG> is similar to the electrical connector assembly <NUM> of <FIG>, except the electrical connector assembly <NUM> of <FIG> further comprises a hole or opening <NUM> in the first contact member <NUM> that is aligned with the bore <NUM> (in the second contact member <NUM>) for receipt of a fastener, such as fastener <NUM> (e.g., threaded bolt or screw) and retainer <NUM> (e.g., nut). Like reference numbers in <FIG> and <FIG> indicate like elements or features.

In certain prior art electronic power modules, such as power inverters, an increase of electrical resistance at an electrical contact interface results in heat generation, which compounds thermal issues. With the connector assembly disclosed in this document, the peak overloading of the electronic power module can be managed while keeping the electronic power module compact (e.g., for installation on a vehicle). The connector assembly has decreased interface thermal resistance while keeping package size compact and smaller than conventional connector assemblies. The shape of the transition area or step promotes an easy flow path for the thermal and electrical energy that passes through it. The contact surface area of the connector assembly is increase at the transition for heat dissipation to ambient air, whereas overall envelop of the connector assembly remains compact by using three-dimensional , non-planar mating surfaces. This conductor assembly can be cooled from two sides or opposite sides of the circuit board <NUM>.

Claim 1:
An electrical connector assembly (<NUM>), comprising:
a first electrically conductive contact member (<NUM>), the first contact member having a non-planar first interface mating surface (<NUM>), the first interface mating surface (<NUM>) comprising a plurality of elongated first ridges (<NUM>) and a plurality of elongated first valleys (<NUM>); and
a second electrically conductive contact member (<NUM>), the second contact member having a non-planar second interface mating surface (<NUM>), the second interface mating surface (<NUM>) comprising a plurality of elongated second ridges (<NUM>) and a plurality of elongated second valleys (<NUM>), wherein the second interface mating surface is complementary to the first interface mating surface and is configured to engage the first interface mating surface in interlocking engagement whereby the contact surface of the connector assembly is increased, wherein the electrical connector assembly is characterized in that:
the first electronically conductive contact member (<NUM>) has a substantially triangular or tear drop shape;
the second electrically conductive contact member (<NUM>) has a substantially circular, substantially elliptical or rounded surface area; and
the first contact member (<NUM>) comprises an outer portion (<NUM>) and an inner portion (<NUM>) which is offset from the outer portion (<NUM>), and wherein the inner portion (<NUM>) is connected to the outer portion (<NUM>) by a step portion (<NUM>).