Low thermal resistance power module assembly

An electronic assembly with low thermal resistance, comprising:

• a metallic spreader plate comprising a lower surface and an upper surface, a heat dissipation opening extending through the plate from the upper surface to the lower surface, and a stress resistant element adjacent the heat dissipation opening;
• a circuit substrate;
• a bonding and sealing layer disposed between the circuit substrate and the plate and bonding the circuit substrate to a portion of the upper surface of the plate adjacent the stress resistant element and to a bonding surface of the stress resistant element proximate to the heat dissipation opening;
• and
• an electric component layer positioned on the circuit substrate comprising an integrated circuit (IC) generating heat during operation, the heat being removed at least in part through the circuit substrate to a cooling medium in the heat dissipation opening, wherein the bonding and sealing layer blocks flow of the cooling medium between the circuit substrate and the plate.

A method of manufacturing a power module assembly with low thermal resistance, comprising:

• providing a power module substrate comprising a plurality of power modules distributed in a pattern on a circuit substrate, the circuit substrate comprising a pair of electrical conductor layers with a ceramic isolation layer sandwiched between;
• providing a metallic plate having a thickness, based on the power module pattern, making a hole through the thickness of the plate for each of the power modules;
• forming a groove in an upper surface of the plate about the periphery of one or more of the holes;
• positioning a sealing member in the groove;
• and
• mating the plate to the power module substrate, wherein the holes in the plate are substantially aligned with the power modules with a central axis of the holes substantially aligned with a center of one of the power modules, the bonding comprising applying a sealing force to a portion of the circuit substrate to compress the sealing member and achieve a liquid seal between the upper surface of the plate and the circuit substrate.

A power module assembly with low thermal resistance, comprising a heat sink plate with a lower surface and an upper surface, said heat sink plate comprising a plurality of passageways for coolant extending from said lower surface to said upper surface;

• a circuit substrate positioned on said heat sink plate covering the coolant passageways, wherein each of said coolant passageways has a circular cross section with a sidewall extending from said lower surface to said upper surface of said heat sink plate;
• said sidewalls are oriented to slope inward from said lower surface such that each of said coolant passageways has a diameter at said lower surface that is greater than a diameter at said upper surface of said heat sink plate;
• said heat sink plate further comprising a recessed surface on said upper surface extending continuously about the periphery of one or more of said coolant passageways;
• a sealing member positioned in said recessed surface of said heat sink plate, said sealing member comprising a compressible material and comprised of an O-ring or a gasket;
• a set of power modules mounted on a circuit substrate opposite a bonding layer, wherein said power modules each comprise an insulated gate bipolar transistor (IGBT) module or a diode and said circuit substrate further comprising a direct bonded copper (DBC) substrate bonded to said bonding layer and to said IGBT module, said DBC substrate comprising a pair of layers of copper sandwiching a ceramic isolation layer, and a structural member positioned to contact a surface of said circuit substrate opposite a surface of said circuit substrate covering said coolant passageways, wherein a sealing force is applied to said circuit substrate via said structural member to compress said sealing member.

An electronic assembly with low thermal resistance, comprising a metallic spreader plate including a lower surface and an upper surface, a heat dissipation opening extending through said plate from said upper surface to said lower surface, and a stress resistant element adjacent said heat dissipation opening;

• a circuit substrate;
• a bonding and sealing layer disposed between said circuit substrate and said plate for bonding said circuit substrate to a portion of said upper surface of said plate adjacent said stress resistant element and to a bonding surface of said stress resistant element proximate to said heat dissipation opening, said stress resistant element comprising at least one bellow, said bellow is not bound to said circuit substrate with said bonding layer, said bellow has a W-shaped cross section and said stress resistant element extends about the periphery of said heat dissipation opening, said bonding and sealing layer is positioned about the periphery of said heat dissipation opening, whereby a cooling medium in said heat dissipation opening contacts said circuit substrate, said bonding and sealing layer comprising a nonporous solder material;
• and an electric component layer positioned on said circuit substrate comprising an integrated circuit (IC) for generating heat during operation, said heat being removed at least in part through said circuit substrate to a cooling medium in said heat dissipation opening, wherein said bonding and sealing layers block flow of said cooling medium between said circuit substrate and said plate, said IC comprising an insulated gate bipolar transistor (IGBT) or a diode and said electronic component layer comprising a silicon die, said circuit substrate comprising a ceramic isolation layer between an upper and a lower layer of electrically conductive material, said lower layer being sealably bonded to said bonding and sealing layers and being at least partially exposed to said cooling medium in said heat dissipation opening.

A method of manufacturing a power module assembly with low thermal resistance comprising, providing a power module substrate including a plurality of power modules distributed in a pattern on a circuit substrate, said circuit substrate comprising a pair of electrical conductor layers with a ceramic isolation layer sandwiched between, said power modules each comprising an insulated gate bipolar transistor (IGBT) in a silicon die, said circuit substrate comprising a direct bonded copper (DBC) substrate, wherein said providing of said power module substrate comprises providing silicon dies with said IGBTs and said DBC substrate and bonding said silicon dies to the second one of said electrical conductor layers in said power module pattern;

• providing a metallic plate having a thickness based on the power module pattern, making a hole through the thickness of said plate for each of said power modules;
• forming a groove in an upper surface of said plate about the periphery of one or more of said holes, said groove in said upper surface of said plate is located so as to define a path that encloses all of said hole;
• positioning a sealing member in said groove, said sealing member is a gasket or O-ring comprising a compressible material;
• and mating said plate to said power module substrate, wherein the holes in said plate are substantially aligned with said power modules with a central axis of said holes substantially aligned with a center of one of said power modules, said holes are tapered with a diameter that increases with distance from said circuit substrate, said bonding comprising applying a sealing force to a portion of said circuit substrate to compress said sealing member and achieve a liquid seal between said upper surface of said plate and said circuit substrate, said sealing force being selected based on said gasket or O-ring to at least partially compress said sealing member, wherein the applying of said sealing force comprises providing a sealing force transmitting member that contacts the portion of said circuit substrate and a housing enclosing said power module substrate.