Title of Invention

POWER SEMICONDUCTOR MODULE AND ASSOCIATED PRODUCTION METHOD

Abstract The invention describes a power semiconductor module of pressure contact design, and an associated production method, for arrangement on a cooling assembly. Load connection elements are in this case each in the form of a metal moulding having at least one contact element, one strip-like section and contact feet which proceed from the latter. The respective strip-like section is arranged parallel to the substrate surface and at a distance from the latter. The contact feet extend from the strip-like section to the substrate and contact-connect the latter in a manner suitable for the circuit. In this case, the load connection elements from a stack, and an elastic intermediate layer is arranged in this case between respective adjacent load connection elements in the region of the respective strip-like sections.
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 AND ASSOCIATED PRODUCTION METHOD
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, which is intended to be arranged on a cooling assembly, and an associated method for producing the power semiconductor module. 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.
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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.
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The invention is based on the object of presenting a power semiconductor module of pressure contact design and an associated production method, in which internal insulation of the power semiconductor module is improved and formation of the pressure contact design is simplified.
According to the invention, the object is achieved by means of the measures of the features of Claims 1 and 8. Preferred embodiments are described in the subclaims.
The inventive concept is based on an arrangement of a power semiconductor module of pressure contact design on a cooling assembly, said power semiconductor module having at least one substrate, at least two power semiconductor components, for example bipolar transistors, which are arranged on the latter, 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 also has load connection elements which are each in the form of a metal moulding having a contact device, 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 interconnects with a load potential or alternatively directly contact-connect the power semiconductor components on the substrate.
According to the invention, the load connection elements form a stack, an elastic intermediate layer being arranged in this case between respective adjacent load
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connection elements in the region of the respective strip-like sections. In comparison with the prior art having only one accumulator, this arrangement of a plurality of elastic intermediate layers has the advantage that the individual load connection elements are arranged flexibly rather than rigidly with respect to one another, and the contact stability is thus considerably improved. In addition, manufacturing tolerances in the length of the respective contact feet of the individual load connection elements with respect to one another are compensated for. As a result of the inventive formation of the stack of load connection elements, all of the contact feet press on their respective contact points on the substrate or on the power semiconductor components with the same force.
The associated method for producing an abovementioned arrangement has the following fundamental steps of:
• producing the stack of load connection elements with an intermediate layer;
• arranging the stack in the housing of the power semiconductor module;
• arranging the pressure-exerting device above the stack;
• temporarily locking the pressure-exerting plate on or in the housing;
• arranging at least one substrate having power semiconductor components, which are arranged on the latter and are connected in a manner suitable for the circuit, in the recess of the housing.
It may be particularly preferred for the strip-like sections of the load connection elements and the contact feet to be produced from a flat metal body using a
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stamping and bending technique, contact devices (402, 424, 444) being connected to said metal body and then being laminated to the elastic intermediate layer (46) to form a stack (4).
This production method has the advantage that, as a result of the prefabricated stack, only a few individual components need to be arranged relative to one another when assembling the power semiconductor module.
The inventive solution is explained further with reference to the exemplary embodiments of Figs. 1 and 2.
Fig. 1 shows a section through a power semiconductor module according to the invention.
Fig. 2 shows a three-dimensional illustration of a stack of load connection elements of the power semiconductor module according to the invention.
Fig. 1 shows a section through a power semiconductor module (1) according to the invention. The latter has a housing (3) having a frame-like housing part which is firmly connected to the cooling assembly (2) of the arrangement. 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 (58) which is not patterned.
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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 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 (4, cf. Fig. 2) in this case, the strip-like sections of the individual load connection elements (40,42,44) each being spaced apart from one another by means of an elastic intermediate layer (46) (a silicone cushion in this case) and being electrically insulated from one another. It is particularly preferred for these silicone cushions (46) to be adhesively bonded to the strip-like sections since the stack (4) is thus in the form of a mounting unit. For reasons of clarity, requisite auxiliary connection elements are not illustrated in this sectional illustration.
The power semiconductor module (1) according to the invention preferably 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).
The insulating material moulding (30) has recesses (32) for leading through the contact feet (400,420,440) of the stack (4, cf. Fig. 2).
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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 in the stack (4, cf. Fig. 2). To this end, the pressure-exerting element has pressure fingers (74) according to the prior art. It may also be preferred for a further elastic layer of the same configuration as the intermediate layer (46) to be arranged between the pressure-exerting element (72) having a flat underside and the stack (4).
According to the prior art, the pressure-exerting element (72) may furthermore be in the form of a plastic moulding having a suitable inner metal core and outer reinforcing structures (76). It is likewise 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 illustration of a stack (4) of load connection elements (40, 42, 44) of the power semiconductor module according to the invention. The load connection elements (40, 42, 44) each having a plurality of contact feet (400, 420, 440) which proceed from the associated strip-like sections (402, 422, 442) are illustrated. The contact devices (404, 424, 444) form the external connections of the power semiconductor module.
A silicone cushion having a minimum thickness of 1 mm is respectively arranged as an elastic intermediate layer (46) between the strip-like sections (402, 422, 442). In this case, the respective elastic intermediate layer (46) simultaneously formed the electrical insulation for the adjacent load connection elements (40, 42, 44) and the pressure-transmitting and pressure-storing element of the power semiconductor module.
It is particularly advantageous if, in the region of the strip-like sections (402, 422, 442), the load connection elements (40, 42, 44) are connected to the respective
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intermediate layer (46) to form a mounting unit. This may be formed using an adhesive bond, for example. However, it is particularly preferred for a laminating method to be used as the connecting technique.
The stack (4) also has recesses (406, 426, 446, 466) in the strip-like sections (402, 422, 442) and the intermediate layer (46) for leading through auxiliary connection elements (not illustrated) in the form of helical springs.
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WE CLAIM:
1. Power semiconductor module (1) of pressure contact design for arrangement on a cooling assembly (50), said power semiconductor module having at least one substrate (5), at least two power semiconductor components (70) which are arranged on the latter, a housing (3), load connection elements (40, 42, 44) and control connection elements which lead to the outside, and a pressure-exerting device, 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 each being in the form of a metal moulding having at least one contact element (404, 424, 444), one strip-like section (402, 422, 442) and contact feet (400, 420, 440) which proceed from the latter, the strip-like section being arranged parallel to the substrate surface and at a distance from the latter, and the contact feet extending from the strip-like section to the substrate (5) and contact-connecting the latter in a manner suitable for the circuit, and the load connection elements (40,42,44) forming a stack (4), and an elastic intermediate layer (46) being arranged in this case between respective adjacent load connection elements in the region of the respective strip-like sections (402,422,442).
2. Power semiconductor module (1) according to Claim 1, the elastic intermediate layer (46) being in the form of a silicone cushion having a minimum thickness of 1 mm.
3. Power semiconductor module (1) according to Claim 1, the elastic intermediate layer (46) simultaneously forming the electrical insulation for the adjacent load connection elements (40,42,44).
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4. Power semiconductor module (1) according to Claim 3, the load connection elements (40,42, 44) being connected to form a unit in the region of the strip-like sections (402, 422, 442), all of the load connection elements being sufficiently electrically insulated from one another in this case, and the pressure-exerting device introducing pressure into this stack (4), and the contact feet (400, 420, 440) thus being electrically conductively connected to interconnects (54) of the substrate (5).
5. Power semiconductor module (1) according to Claim 1, a further elastic layer being arranged between a pressure-exerting element (72) of the pressure-exerting device (70) and the stack (4).
6. Power semiconductor module (1) according to Claim 1, the stack (4) being formed by means of adhesive bonding.
7. Power semiconductor module (1) according to one of the preceding claims, the pressure-exerting device (70) and the stack (4) having recesses (406, 426, 446, 466) for leading through auxiliary connection elements which are in the form of helical springs.
8. Method for producing a power semiconductor module (1), which is intended to be arranged on a cooling assembly, according to Claim 1, characterized by the following steps of:

• producing the stack (4) of load connection elements (40, 42, 44) with intermediate layers (46);
• arranging the stack (4) in the housing (3) of the power semiconductor
module (1);
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• arranging the pressure-exerting device (70) above the stack (4);
• temporarily locking the pressure-exerting plate (72) on or in the
housing (3);
• arranging at least one substrate (5) having power semiconductor components (60), which are arranged on the latter and are connected in a manner suitable for the circuit, in the recess of the housing (3).
9. Method (1) according to Claim 8, the strip-like sections (402, 422, 442) of the load connection elements (40, 42, 44) and the contact feet (400, 420, 440) being produced from a flat metal body using a stamping and bending technique, contact devices (402, 424, 444) being connected to said metal body and then being laminated to the elastic intermediate layer (46) to form a stack (4).
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Dated this 22nd day of January 2007


ABSTRACT
The invention describes a power semiconductor module of pressure contact design, and an associated production method, for arrangement on a cooling assembly. Load connection elements are in this case each in the form of a metal moulding having at least one contact element, one strip-like section and contact feet which proceed from the latter. The respective strip-like section is arranged parallel to the substrate surface and at a distance from the latter. The contact feet extend from the strip-like section to the substrate and contact-connect the latter in a manner suitable for the circuit. In this case, the load connection elements form a stack, and an elastic intermediate layer is arranged in this case between respective adjacent load connection elements in the region of the respective strip-like sections.
To,
The Controller of Patents,
The Patent Office, Mumbai


Documents:

128-MUM-2007-ABSTRACT(22-1-2007).pdf

128-MUM-2007-ABSTRACT(GRANTED)-(24-5-2011).pdf

128-mum-2007-abstract.doc

128-mum-2007-abstract.pdf

128-MUM-2007-CANCELLED PAGES(25-4-2011).pdf

128-MUM-2007-CLAIMS(22-1-2007).pdf

128-MUM-2007-CLAIMS(AMENDED)-(25-4-2011).pdf

128-MUM-2007-CLAIMS(GRANTED)-(24-5-2011).pdf

128-MUM-2007-CLAIMS(MARKED COPY)-(25-4-2011).pdf

128-mum-2007-claims.doc

128-mum-2007-claims.pdf

128-mum-2007-correspondence(12-3-2007).pdf

128-MUM-2007-CORRESPONDENCE(25-4-2011).pdf

128-MUM-2007-CORRESPONDENCE(IPO)-(24-5-2011).pdf

128-mum-2007-correspondence-received.pdf

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

128-MUM-2007-DESCRIPTION(COMPLETE)-(22-1-2007).pdf

128-MUM-2007-DESCRIPTION(GRANTED)-(24-5-2011).pdf

128-MUM-2007-DRAWING(22-1-2007).pdf

128-MUM-2007-DRAWING(25-4-2011).pdf

128-MUM-2007-DRAWING(GRANTED)-(24-5-2011).pdf

128-mum-2007-drawings.pdf

128-MUM-2007-EP & US PATENT DOCUMENT(25-4-2011).pdf

128-mum-2007-form 1(12-3-2007).pdf

128-MUM-2007-FORM 1(22-1-2007).pdf

128-MUM-2007-FORM 1(25-4-2011).pdf

128-MUM-2007-FORM 18(22-1-2007).pdf

128-MUM-2007-FORM 2(COMPLETE)-(22-1-2007).pdf

128-MUM-2007-FORM 2(GRANTED)-(24-5-2011).pdf

128-MUM-2007-FORM 2(TITLE PAGE)-(COMPLETE)-(22-1-2007).pdf

128-MUM-2007-FORM 2(TITLE PAGE)-(GRANTED)-(24-5-2011).pdf

128-MUM-2007-FORM 3(22-1-2007).pdf

128-MUM-2007-FORM 3(25-4-2011).pdf

128-MUM-2007-FORM 5(22-1-2007).pdf

128-mum-2007-form-1.pdf

128-mum-2007-form-18.pdf

128-mum-2007-form-2.doc

128-mum-2007-form-2.pdf

128-mum-2007-form-26.pdf

128-mum-2007-form-3.pdf

128-mum-2007-form-5.pdf

128-MUM-2007-GENERAL POWER OF ATTORNEY(22-1-2007).pdf

128-mum-2007-other document(12-3-2007).pdf

128-MUM-2007-PETITION UNDER RULE 137(25-4-2011).pdf

128-MUM-2007-REPLY TO EXAMINATION REPORT(25-4-2011).pdf

128-mum-2007-specification(amended)-(25-4-2011).pdf

abstract1.jpg


Patent Number 247815
Indian Patent Application Number 128/MUM/2007
PG Journal Number 21/2011
Publication Date 27-May-2011
Grant Date 24-May-2011
Date of Filing 22-Jan-2007
Name of Patentee SEMIKRON ELEKTRONIK GMBH & CO. KG
Applicant Address POSTFACH 820251, 90253 NURNBERG,
Inventors:
# Inventor's Name Inventor's Address
1 RAINER POPP ADLERSTR. 16, 91580 PETERSAURACH, GERMANY
PCT International Classification Number H01L23/28
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 102006006423.2 2006-02-23 Germany