Method of manufacturing a thermally conductive circuit board with a ground pattern connected to a heat sink

• US 6,860,004 B2
• Filed: 12/03/2002
• Issued: 03/01/2005
• Est. Priority Date: 04/26/2000
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Nakatani, Seiichi, Hirano, Koichi, Yamashita, Yoshihisa, Matsuo, Mitsuhiro
• Primary Examiner(s): Arbes, Carl J.
• Assistant Examiner(s): NGUYEN, TAI V
• Application Number:
  US10/309,707
• Publication Number:
  US 20030076663A1
• Time in Patent Office: 819 Days
• Field of Search: 298/27, 298/41, 298/32, 298/48, 298/55, 298/56, 361/760, 361/746, 361/748, 361/813, 361/713, 174/258, 174/259, 174254-257, 174/51, 174/78
• US Class Current: 29/832
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/451 with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 23/3737 Organic materials with or without a thermoconductive filler
• CPC Class Codes: H01L 23/4334 Auxiliary members in encapsulations H01L23/49568 takes precedence
• CPC Class Codes: H01L 23/49861 Lead-frames fixed on or encapsulated in insulating substrates H01L23/4985, H01L23/49805 take precedence
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01046 Palladium [Pd]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/1305 Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/13055 Insulated gate bipolar transistor [IGBT]
• CPC Class Codes: H01L 2924/19041 being a capacitor
• CPC Class Codes: H05K 1/0204 using means for thermal conduction connection in the thickness direction of the substrate H05K1/0207 takes precedence
• CPC Class Codes: H05K 1/056 the metal substrate being covered by an organic insulating layer
• CPC Class Codes: H05K 2201/0209 : Inorganic, non-metallic particles
• CPC Class Codes: H05K 2201/0382 : Continuously deformed conductors
• CPC Class Codes: H05K 2201/09054 : Raised area or protrusion of metal substrate
• CPC Class Codes: H05K 2201/0969 : Apertured conductors
• CPC Class Codes: H05K 2201/10416 : Metallic blocks or heatsinks completely inserted in a PCB metallic supports H05K3/0061
• CPC Class Codes: H05K 2203/1189 : Pressing leads, bumps or a die through an insulating layer
• CPC Class Codes: H05K 3/0061 : onto a metallic substrate, e.g. a heat sink heat sinks for electric apparatus H05K7/20
• CPC Class Codes: H05K 3/202 : using self-supporting metal foil pattern
• CPC Class Codes: H05K 3/4084 : by deforming at least one of the conductive layers
• CPC Class Codes: H05K 7/20463 : Filling compound, e.g. potted resin
• CPC Class Codes: H05K 7/205 : Heat-dissipating body thermally connected to heat generating element via thermal paths through printed circuit board [PCB] details of PCBs relating to heat transfer H05K1/0201
• CPC Class Codes: Y10T 29/49121 : Beam lead frame or beam lead device
• CPC Class Codes: Y10T 29/4913 : Assembling to base an electrical component, e.g., capacitor, etc.
• CPC Class Codes: Y10T 29/49146 : with encapsulating, e.g., potting, etc.
• CPC Class Codes: Y10T 29/49158 : with molding of insulated base
• CPC Class Codes: Y10T 29/49171 : with encapsulating
• CPC Class Codes: Y10T 29/49172 : by molding of insulating material

Abstract

In a method of manufacturing a thermally conductive circuit board with high heat dissipation, high conductivity and high ground-connection, a sheet-like thermally conductive resin composition containing 70 to 95 wt. % inorganic filler and 5 to 30 wt. % thermosetting resin composition, a lead frame as a wiring pattern, and an electrically conductive heat sink with a metal pole placed therein are superposed, heated and compressed, and thus are combined to form one body. Consequently, a thermally conductive circuit board with a flat surface is obtained in which a grounding pattern is grounded to the heat sink inside the insulating layer. Thus, the grounding pattern and the heat sink can be connected electrically with each other in an arbitrary position inside the insulating layer of the thermally conductive circuit board. The method provides that a part of a lead frame and heat sink are connected not only mechanically, but also electrically, and allows an associated power module size to be reduced and its density to be increased.

Claims

1. A method of manufacturing a thermally conductive circuit board with a grounding pattern connected to a heat sink, where a part of the lead frame and the heat sink are connected electrically, the method comprising:

(1) placing a metal pole in a desired place in a lead frame as a wiring pattern; and

(2) superposing the lead frame, a sheet-like thermally conductive resin composition made of 70 to 95 wt. % inorganic filler and 5 to 30 wt. % resin composition containing at least uncured thermosetting resin, and an electrically conductive heat sink sequentially with a portion of the metal pole protruding from the lead frame facing the sheet-like thermally conductive resin composition, and heating and compressing them, so that the metal pole is connected to the electrically conductive heat sink, the sheet-like thermally conductive resin composition is allowed to fill up to a surface of the lead frame, and the thermosetting resin contained in the sheet-like thermally conductive resin composition is cured.

2. The method of manufacturing a thermally conductive circuit board according to claim 1, further comprising forming a hole in a desired place in at least one of the electrically conductive heat sink and the lead frame, the hole having a shape corresponding to a shape of the metal pole, and fitting the metal pole into the hole.

3. The method of manufacturing a thermally conductive circuit board according to claim 1, wherein an end of the metal pole to be connected to the electrically conductive hear sink or the lead frame has a conoidal shape, and in the process (2), the end with the conoidal shape of the metal pole bites into and is connected to the electrically conductive heat sink or the lead frame.