Title of Invention

POWER SEMICONDUCTOR MODULE OF PRESSURE CONTACT PATTERN

Abstract

The invention describes a power semiconductor module of pressure contact design for arrangement on a cooling assembly, load connection elements each being in the form of a mental moulding having at least one strip-like section and a plurality of contact feet which proceed from the latter. In this case, a respective strip-like section of the load connection element is arranged parallel to the substrate surface and at a distance from the latter. Furthermore, contact feet extend from the strip-like section to the substrate where they form the contacts of the load connections in manner suitable for the circuit. An insulating material moulding is arranged between the strip-like section of the load connection elements and substrate and has recess for leading through the contact feet.

Full Text

FORM 2 THE PATENT ACT 1970 (39 of 1970) & The Patents Rules, 2003 COMPLETE SPECIFICATION (See Section 10, and rule 13) 1. TITLE OF INVENTION : POWER SEMICONDUCTOR MODULE OF PRESSURE CONTACT DESIGN 2. APPLICANT(S) a) Name : SEMIKRON ELEKTRONIK GMBH & CO. KG b) Nationality : GERMAN Company C) Address : POSTFACH 820251, 90253 NURNBERG, GERMANY 3. PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed : - Description The invention describes a power semiconductor module of pressure contact design having controllable power semiconductor components. Power semiconductor modules as are disclosed, by way of example, in DE 197 19 703 Al form a starting point of the invention. According to the prior art, such power semiconductor modules comprise a housing having at least one electrically insulating substrate which is arranged in the latter and is preferably intended to be directly mounted on a cooling assembly. For its part, the substrate comprises an insulating material body having a plurality of metal interconnects, which are situated on said insulating material body and are insulated from one another, and power semiconductor components which are situated on said interconnects and are connected to the latter in a manner suitable for the circuit. The known power semiconductor modules also have connection elements for external load connections and auxiliary connections and connecting elements which are arranged inside. These connecting elements for connections, which are suitable for the circuit, inside the power semiconductor module are usually in the form of wire bonding connections. Power semiconductor modules in which contact is made by pressure and which are disclosed in DE 42 37 632 Al, DE 199 03 875 Al or DE 101 27 947 CI are likewise known. In the document mentioned first, the pressure-exerting device has a stable, preferably metal pressure-exerting element for building up pressure, an elastic cushion element for storing pressure, and a bridge element for introducing pressure into separate regions of the substrate surface. The bridge element is preferably in the form of a plastic moulding having a surface which faces the cushion element and from which a multiplicity of pressure fingers proceed in the direction of the substrate surface. 2 Such a pressure-exerting device is used to press the substrate onto a cooling assembly and thus to reliably permanently establish heat transfer between the substrate and the cooling assembly. In this case, the elastic cushion element is used to maintain constant pressure conditions for different thermal loads over the entire lifecycle of the power semiconductor module. DE 199 03 875 Al further develops the known pressure-exerting element in such a manner that it has, on the one hand, a particularly advantageous weight/stability ratio and, on the other hand, electrically insulated bushings. To this end, the pressure-exerting element is in the form of a plastic moulding having an inner metal core. This metal core has recesses for leading through connection elements, preferably auxiliary connection elements of spring contact design. The plastic moulding surrounds these recesses in such a manner that the auxiliary connection elements are electrically insulated from the metal core using the plastic moulding. Pressure-exerting elements which have been developed further and have a multiplicity of pressure fingers on their surface facing the substrate are also known. In this case, the metal core preferably still has preset flexure. The combination of both measures makes it possible for such a pressure-exerting element to provide the entire functionality of a pressure-exerting device mentioned above. DE 101 57 947 CI discloses a power semiconductor module, the load connection elements being designed in such a manner that they run closely adjacent and perpendicular to the substrate surface in sections and have contact feet which proceed from there, make electrical contact with the interconnects and simultaneously exert pressure on the substrate and thus establish thermal contact between said substrate and a cooling assembly. In this case, the pressure is introduced and stored using means according to the prior art. DE 10 2004 021 927 Al discloses a method for internally insulating power semiconductor modules, in which case, in contrast to the previously known prior art, 3 said power semiconductor modules are not filled with an insulating silicone gel up to a defined filling height. In contrast to this, said document presents a method for coating the components and connecting elements to be insulated, which saves a considerable amount of silicone gel. The invention is based on the object of presenting a power semiconductor module of pressure contact design in which internal insulation is improved, formation of the pressure contact design is simplified, and the power semiconductor module is advantageously designed for the use of a coating method for insulating the substrate. According to the invention, the object is achieved by means of the measures of the features of Claim 1. Preferred embodiments are described in the subclaims. The inventive concept is based on a power semiconductor module of pressure contact design for arrangement on a cooling assembly, said power semiconductor module having at least one substrate, at least two controllable power semiconductor components, for example bipolar transistors, a housing, and load connection elements and control connection elements which lead to the outside. The substrate itself has an insulating material body and interconnects with a load potential on its first main surface facing the inside of the power semiconductor module. Furthermore, the substrate preferably also has at least one interconnect with a control potential for driving the power semiconductor components. The power semiconductor module according to the invention also has load connection elements which are each in the form of a metal moulding having a strip-like section and a plurality of contact feet which proceed from the latter. The respective strip-like sections are arranged parallel to the substrate surface and at a distance from the latter. The contact feet which proceed from the strip-like section extend to the substrate where they form the contacts of the load connections in a manner suitable for the circuit. To this end, they preferably contact-connect the 4 interconnects with a load potential or else directly contact-connect the individual power semiconductor components on the substrate. Furthermore, an insulating material moulding is arranged between the strip-like sections of the load connection elements, which form a stack in this case, and the substrate. This insulating material moulding has recesses for leading through the contact feet. In this case, the insulating material moulding preferably forms a completely closed area which solely has recesses for electrical connection elements. It may also be preferred for the insulating material moulding to also have recesses for devices for fastening the power semiconductor module to the cooling assembly. Power semiconductor modules of pressure contact design which have been formed in this manner have considerably improved internal insulation an account of the additional insulating intermediate layer between the strip-like sections of the load connection elements and the substrate having the power semiconductor components and the module-internal connections. This allows improved fault tolerance during continuous operation of the power semiconductor module. Advantageous additional guide devices for the load connection elements, which are integrally formed with this intermediate layer, simultaneously simplify formation of the pressure contact design, the load connection elements being used to introduce pressure into the substrate and thus to thermally connect the latter to a cooling assembly. This refinement of the power semiconductor module is particularly preferred in combination with modern coating methods for internally insulating the substrate since, in this case, the entire internal insulation is particularly advantageous and accessible for automated manufacture. The inventive solution is explained further with reference to the exemplary embodiments of Figs. 1 to 3. 5 Fig. 1 shows a section through a power semiconductor module according to the invention. Fig. 2 shows a three-dimensional exploded illustration of a power semiconductor module according to the invention. Fig. 3 shows a three-dimensional illustration of load connection elements and substrates of a power semiconductor module according to the invention. Fig. 1 shows a section along the line A-A (cf. Fig. 2) through a power semiconductor module (1) according to the invention. The latter has a housing (3) having a frame-like housing part. In this case, the frame-like housing part surrounds the at least one substrate (5). The latter, in turn, has an insulating material body (52), preferably an insulating ceramic such as aluminium oxide or aluminium nitrate. The substrate (5) has a metal coating, which is not patterned per se, on the first main surface facing the inside of the power semiconductor module (1). In this case, the individual sections of this metal coating, which is preferably in the form of a copper coating, form the interconnects (54) of the power semiconductor module (1). The second main surface of the substrate (5) has, according to the prior art, a copper coating (56) which is not patterned. Controllable and/ or uncontrolled power semiconductor components (60), for example IGBTs (insulated gate bipolar transistor) with respective freewheeling diodes which are connected back-to-back, or MOSFETs, are arranged on the interconnects (54) of the substrate (5). These components are connected to further interconnects (54) in a manner suitable for the circuit, for example by means of wire bonding connections (62). The load connection elements (40, 42, 44) with the different requisite potentials are used to externally connect the power-electronic circuit inside the power semiconductor module (1). To this end, the load connection elements (40,42,44) are 6 in the form of metal mouldings each having a strip-like section (402, 422, 442) parallel to the substrate surface. The strip-like sections (402, 422, 442) form a stack in this case, the strip-like sections of the individual load connection elements (40, 42, 44) being spaced apart from one another solely by means of requisite insulation (46), for example in the form of a plastic film. For reasons of clarity, requisite auxiliary connection elements are not illustrated in this sectional illustration. Furthermore, the power semiconductor module (1) according to the invention has an intermediate layer in the form of an insulating material moulding (30) between the stack of strip-like sections (402, 422, 442) of the load connection elements (40, 42, 44) and the substrate (5). In this refinement, this insulating material moulding (30) is arranged in the frame-like housing (3) by means of a snap-action latching connection (90). The insulating material moulding (30) has, for its part, recesses (32) for leading through the contact feet (400, 420, 440) of the load connection elements (40,42,44). It is particularly preferred for these recesses (32) to be in the form of guides for these contact feet (400, 42, 44), thus improving the positioning of the load connection elements (40, 42, 44) relative to the substrate (5) and the positioning of the interconnects (54) of the latter relative to an arrangement having simple recesses again. In another particularly preferred refinement of the insulating material moulding, the recesses (32) for leading through the contact feet are in the form of shafts (34), these shafts (34) extending close to the surface of the substrate (5). These shafts (34) advantageously extend into the insulating material layer, for example a silicone gel, the silicone gel being applied to the substrate (5) using a modern coating method. This forms particularly effective internal insulation of the power semiconductor module (1). 7 The pressure-exerting device (70) for thermally connecting the power semiconductor module (1) to a cooling assembly (2) and for simultaneously electrically contact-connecting the load connection elements (40, 42, 44) to the interconnects (54) of the substrate (5) is formed by a pressure-exerting element (72) for building up pressure as well as an elastic cushion element (not illustrated) for storing pressure. The pressure is introduced into the stack of strip-like sections (402, 422, 442) of the load connection elements (40, 42, 44) via the cushion element, and thus exerts pressure on the contact feet (400, 420, 440). The latter are thus electrically conductively connected to interconnects (54) of the substrate (5). Such pressure contact connections (70) have been proven to have a particularly high contact stability over the lifetime of power semiconductor modules (1). Designing the recesses (32) of the insulating material moulding (30) in the form of guides or shafts (34) is also advantageous for pressure contact connection since the positioning of the contact feet (400, 420, 440) is particularly accurate as a result. According to the prior art, the pressure-exerting element (72) may be in the form of a plastic moulding having a suitable inner metal core which is in the form of a bimetal, for example, it being possible to dispense with a pressure-storing cushion element in this case too. It is also preferred for the pressure-exerting element (72) to be simultaneously used as a cover of the power semiconductor module (1). Fig. 2 shows a three-dimensional exploded illustration of part of the power semiconductor module (1) according to the invention. A plastic housing (3) having devices (300) for fastening the latter to a cooling assembly is illustrated in this case. The housing (3) has an insulating material moulding (30) which is integrally formed with the latter and forms an intermediate layer between the substrate (5), which is arranged beneath this intermediate layer, and the strip-like sections (402,422,442) of the load connection elements (40, 42, 44), which are arranged above this intermediate layer. 8 Furthermore, the housing (3) has fastening devices (302) for a pressure-exerting element (72) (not illustrated) as well as dome-like bushings (38) for auxiliary connection elements (80). In such power semiconductor modules (1) in which contact is made by pressure, it is particularly preferred for the auxiliary connection elements to be in the form of contact springs (80), preferably helical springs. The load connection elements (40, 42, 44) for the different load potentials are each in the form of a metal moulding having a contact device (404, 424, 444) for external connection, at least one strip-like section (402, 422, 442) which runs parallel to the substrate surface, and a plurality of contact feet (400, 420, 440) which proceed from this section. The respective load connection elements (40, 42, 44) are spaced apart from one another, if necessary, by means of an insulating plastic film (46) and are electrically insulated from one another. The AC connection element (40) also has a current sensor (410) which is arranged adjacent to the contact device (404). The contact feet (400, 420, 440) of the load connection elements (40, 42, 44) extend, through the recesses (32) of the insulating material moulding (30) which are in the form of guides, to the associated contact areas of the interconnects (54) of the substrate (5) or of the power semiconductor components (60). The strip-like sections (402, 422, 442) of the load connection elements (40, 42, 44) and their associated insulating plastic films (46) have, for their part, recesses (406, 426, 446, 466) in those regions in which the housing (3) has domes (38) for the auxiliary connection elements (80). The associated pressure-exerting device (70) (not illustrated) likewise has, for its part, corresponding recess, aligned with the recess of the load connection elements, for leading through the auxiliary connection elements. Fig. 3 shows a three-dimensional view of load connection elements (40, 42, 44) of a power semiconductor module (1) according to the invention and their position with respect to two substrates (5), in which case the housing and the pressure-exerting device are not illustrated. For reasons of clarity, the insulating plastic films between 9 the individual load connection elements (40, 42, 44) are likewise not illustrated. The illustrated circuit of the power semiconductor module is a half-bridge circuit having a plurality of bipolar transistors (60) which are connected in parallel and form the respective first and second switches. The circuit likewise has the requisite freewheeling diodes (64). In this case, half of the first and second switches of the half-bridge circuit are respectively distributed between two identical substrates. The plurality of contact feet (400, 420, 440) which proceed from the associated strip-like sections (402, 422, 442) of the respective load connection element (40, 42, 44) are illustrated. In this case, a plurality of contact feet (400, 420, 440) of the same polarity respectively contact-connect the associated interconnects (54) of the respective polarity on both substrates (5). The electrical connection which has a permanently high contact stability is formed using the pressure-exerting device described above. Recess (406, 426, 446) of the stack of load connection elements (40, 42, 44), which are provided for the arrangement of the auxiliary connection elements (80) shown in Fig. 2, are also illustrated. 10 WE CLAIM: 1. Power semiconductor module (1) of pressure contact design for arrangement on a cooling assembly (2), said power semiconductor module having at least one substrate (5), at least two power semiconductor components (60, 64) which are arranged on the latter, a housing (3), load connection elements (40, 42,44) and auxiliary connection elements (80) which lead to the outside, and a pressure-exerting device (70), the substrate (5) having an insulating material body (52), and interconnects (54) with a load potential being arranged on the first main surface of said substrate which faces the inside of the power semiconductor module, the load connection elements (40, 42, 44) each being in the form of a metal moulding having at least one strip-like section (402, 422, 442) and a plurality of contact feet (400, 420, 440) which proceed from the latter, a respective strip-like section (402, 422, 442) of the load connection element being arranged parallel to the substrate surface and at a distance from the latter, and the contact feet (400, 420, 440) extending from the strip-like section (402, 422, 442) to the substrate (5) where they form the contacts of the load connections in a manner suitable for the circuit, and an insulating material moulding (30) being arranged between the strip-like section (402, 422, 442) of the load connection elements (40, 42, 44) and the substrate (5) and having recesses (32) for leading through the contact feet (400,420,440). 2. Power semiconductor module (1) according to Claim 1, the the recesses (32) of the insulating material moulding (30) for leading through the contact feet (400, 420, 440) being in the form of guides for this purpose, and the contact feet (400, 420, 440) contact-connecting the interconnects (54) of the substrate (5). 3. Power semiconductor module (1) according to Claim 1, the insulating material moulding (30) and the housing (3) being integrally formed. 11 4. Power semiconductor module (1) according to Claim 1, the recesses (32) of the insulating material moulding (30) for leading through the contact feet being in the form of shafts (34), and these shafts (34) extending close to the surface of the substrate (5) and extending into an insulation layer. 5. Power semiconductor module (1) according to Claim 1, the strip-like sections (400, 420, 440) of the load connection elements (40, 42, 44) forming a stack in which they are electrically insulated from one another, and the pressure-exerting device (70) exerting pressure on this stack, and the contact feet (400, 420, 440) thus being electrically conductively connected to interconnects (54) of the substrate (5). 6. Power semiconductor module (1) according to Claim 1, the pressure-exerting device (70), the strip-like sections (402, 422, 442) of the load connection elements (40, 42, 44) and the insulating material moulding (30) having recesses (32) for leading through auxiliary connection elements (80) which are in the form of helical springs having contact devices. 7. Power semiconductor module (1) according to Claim 6, the insulating material moulding (30) having domes (38) around the recesses for leading through the auxiliary connection elements (80). 12 Dated this 23rd day of January, 2007 Abstract The invention describes a power semiconductor module of pressure contact design for arrangement on a cooling assembly, load connection elements each being in the form of a metal moulding having at least one strip-like section and a plurality of contact feet which proceed from the latter. In this case, a respective strip-like section of the load connection element is arranged parallel to the substrate surface and at a distance from the latter. Furthermore, contact feet extend from the strip-like section to the substrate where they form the contacts of the load connections in manner suitable for the circuit. An insulating material moulding is arranged between the strip-like section of the load connection elements and the substrate and has recesses for leading through the contact feet. To, The Controller of Patents The Patent Office Mumbai. 13 (Fig-1)

Documents:

136-MUM-2007-ABSTRACT(23-1-2007).pdf

136-MUM-2007-ABSTRACT(25-9-2009).pdf

136-MUM-2007-ABSTRACT(AMENDED)-(25-9-2009).pdf

136-MUM-2007-ABSTRACT(GRANTED)-(25-1-2010).pdf

136-mum-2007-abstract.doc

136-mum-2007-abstract.pdf

136-MUM-2007-CANCELLED PAGES(25-9-2009).pdf

136-MUM-2007-CLAIMS(23-1-2007).pdf

136-MUM-2007-CLAIMS(25-9-2009).pdf

136-MUM-2007-CLAIMS(GRANTED)-(25-1-2010).pdf

136-mum-2007-claims.doc

136-mum-2007-claims.pdf

136-MUM-2007-CORRESPONDENCE(12-3-2007).pdf

136-MUM-2007-CORRESPONDENCE(25-9-2009).pdf

136-MUM-2007-CORRESPONDENCE(IPO)-(27-1-2010).pdf

136-mum-2007-correspondence-received.pdf

136-mum-2007-description (complete).pdf

136-MUM-2007-DESCRIPTION(COMPELE)-(23-1-2007).pdf

136-MUM-2007-DESCRIPTION(COMPLETE)-(25-9-2009).pdf

136-MUM-2007-DESCRIPTION(GRANTED)-(25-1-2010).pdf

136-MUM-2007-DRAWING(23-1-2007).pdf

136-MUM-2007-DRAWING(25-9-2009).pdf

136-MUM-2007-DRAWING(GRANTED)-(25-1-2010).pdf

136-mum-2007-drawings.pdf

136-MUM-2007-FORM 1(25-9-2009).pdf

136-mum-2007-form 2(25-9-2009).pdf

136-MUM-2007-FORM 2(COMPELE)-(23-1-2007).pdf

136-MUM-2007-FORM 2(GRANTED)-(25-1-2010).pdf

136-MUM-2007-FORM 2(TITLE PAGE )-(COMPELE)-(23-1-2007).pdf

136-MUM-2007-FORM 2(TITLE PAGE)-(25-9-2009).pdf

136-MUM-2007-FORM 2(TITLE PAGE)-(GRANTED)-(25-1-2010).pdf

136-mum-2007-form-1.pdf

136-mum-2007-form-18.pdf

136-mum-2007-form-2.doc

136-mum-2007-form-2.pdf

136-mum-2007-form-26.pdf

136-mum-2007-form-3.pdf

136-mum-2007-form-5.pdf

136-MUM-2007-REPLY TO EXAMINATION REPORT(25-9-2009).pdf

136-MUM-2007-SPECIFICATION(AMENDED)-(25-9-2009).pdf

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