# US 2008/0186682 A1 · Method for producing a printed circuit board with a heat radiating structure and a printed circuit board with a heat radiating structure > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0186682 A1 - Document ID: US20080186682A1 - Status: Published application - Kind: A1 - Application number: 11/903,154 - Filed: 2007-09-20 - Published: 2008-08-07 - Earliest claimed: 2006-09-20 - Assignees: Sumitomo Wiring Systems, Ltd. - Inventors: Yoshiaki Sugimura - Web page: https://patentgrep.com/patent/US20080186682A1 ## CPC - H05K 1/0206: {by printed thermal vias} - H05K 3/341: Surface mounted components - H05K 3/3485: Application of solder paste, slurry or powder (using printing techniques to form the desired conductive pattern of the printed circuit by applying conductive material H05K3/12) - H05K 2201/09572: Solder filled plated through-hole in the final product - H05K 2201/10689: Leaded Integrated Circuit [IC] package, e.g. dual-in-line [DIL] - H05K 2201/10969: Metallic case or integral heatsink of component electrically connected to a pad on PCB - H05K 2203/043: Reflowing of solder coated conductors, not during connection of components, e.g. reflowing solder paste - H05K 2203/0455: PTH for surface mount device [SMD], e.g. wherein solder flows through the PTH during mounting - H05K 2203/1572: Processing both sides of a PCB by the same process; Providing a similar arrangement of components on both sides; Making interlayer connections from two sides - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - Y10T 29/49144: by metal fusion - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A first surface of a double-sided printed circuit board has a soldering land for heat radiation, which serves as a mounting surface for an electronic part. A land for solder absorption is formed on the second surface facing the mounting surface. Viaholes are provided and open in both the soldering land for heat radiation and the land for solder absorption at the opposite ends. Molten solder flows out from the openings of the viaholes and spreads on the land for solder absorption to suppress formation of solder balls. Cream solder is applied to the outer surface of the land for solder absorption to embed the solder and to form a solder layer. ## Claims ### Claim 1 A method for producing a printed circuit board (100) with at least one heat radiating structure, comprising the steps of: preparing a printed circuit board (100) having conductor patterns (13) and lands (16; 17) made of conductive foil formed on first and second surfaces (12a; 12b) of an insulating substrate (12), at least one soldering land (22) for heat radiation on the first surface (12a) to define a mounting surface for an electronic part (20) and at least one land (25) for solder absorption on the second surface (12b), at least one viahole (24) with opposite first and second openings (24a, 24b) respectively in the soldering land (22) for heat radiation and the land (25) for solder absorption; placing a first metal mask (35) on the first surface; applying a cream solder (36) to the lands (16; 17) and the soldering land (22) for heat radiation; placing the electronic part (20) on the first surface; melting the first solder (36) in a first reflow process to solder-connect lead terminals (20b; 20c) of the electronic part (20) to the lands (16; 17) and to cause the molten solder to flow through the viahole (24) and onto the land (25) for solder absorption adjacent the second openings (24b); placing a second metal mask (40) on the second surface (12b); applying s second solder (41) to the land (25) for solder absorption to at least partly cover portions of the first cream solder (36) solidified adjacent the second opening (24b) of the viahole (24); and melting the second solder (41) in a second reflow process to form a solder layer on the land (25) for solder absorption. ### Claim 2 (depends on 1) The method of claim 1, further comprising forming at least one solder resist (18; 26) on solder unnecessary parts of at least one of the first and second surfaces (12a; 12b) to at least partly at least one of surround the soldering land (22) for heat radiation and the land (25) for solder absorption. ### Claim 3 (depends on 1) The method of claim 1, wherein the first reflow process comprises forming a layer of the first solder (36) at least partly adhering to the soldering land (22) for heat radiation and to the electronic part (20). ### Claim 4 (depends on 1) The method of claim 1, wherein a thickness of the first solder (36) for the first reflow process is substantially equal to a thickness of the first metal mask (35). ### Claim 5 (depends on 1) The method of claim 1, wherein portions the first solder (36) that flows through the viahole (24) and onto the second surface (12b) forms at least one solder deposition (31) having a projecting height less than a thickness (t) of the second metal mask (40) used in the second reflow process. ### Claim 6 (depends on 5) The method of claim 5, wherein the second solder (41) is applied to the land (25) for solder absorption to substantially the same height as the second metal mask (40) while at least partly covering solder deposition (31) adjacent the second opening (24b) of the respective viahole (24). ### Claim 7 (depends on 1) The method of claim 1, wherein the steps of applying the first and second solders (36; 41) comprises applying a first cream solder (36) and a second cream solder (41). ### Claim 8 A heat radiating structure for a printed circuit board, comprising: a substrate (12) with opposite first and second surfaces (12a; 12b) and conductor patterns (13) provided on at least one of surfaces (12a; 12b); at least one soldering land (22) for heat radiation in an area of the first surface (12a) where an electronic part (20) is to be mounted, at least one land (25) for solder absorption on the second surface (12b) and at least one viahole (24) with a first opening (24a) in the soldering land (22) for heat radiation and a second opening (24b) in the land (25) for solder absorption; a first unitary matrix of solder (36) between the electronic part (20) and the soldering land (22) for heat radiation, the unitary matrix of solder (36) extending through the viahole (24) and spread onto areas of the land (25) for solder absorption adjacent the second opening (24b) of the viahole (24) and adhering to the land (25) for solder absorption in a substantially flat manner; and a second unitary matrix of solder (41) at least partly covering portions of the first unitary matrix of solder (31) adhering to the land (25) for solder absorption. ### Claim 9 (depends on 8) The heat radiating structure of claim 8, wherein the land (25) for solder absorption is at least partly registered with the soldering land (22) for heat radiation in a thickness direction (TD) of the substrate (12). ### Claim 10 (depends on 9) The heat radiating structure of claim 9, wherein the land (25) for solder absorption and the soldering land (22) for heat radiation have substantially equal surface areas. ### Claim 11 (depends on 8) The heat radiating structure of claim 8, wherein the at least one viahole (24) comprises a plurality of viaholes (24) are arranged at specified intervals in forward and backward directions and a transverse direction. ### Claim 12 (depends on 11) The heat radiating structure of claim 11, wherein an outer edge of the land (25) for solder absorption is outwardly at a specified distance from the viaholes (24). ### Claim 13 (depends on 8) The heat radiating structure of claim 8, wherein lead terminals (20b; 20c) project from the outer side surface of the electronic part (20) and are solder-connected respectively to lands (16; 17) on the first surface (12a). ### Claim 14 (depends on 13) The heat radiating structure of claim 13, wherein the electronic part (20) includes a heat radiating member (21), and the first solder matrix (36) on the soldering land (22) for heat radiation is secured substantially in surface contact with the heat radiating member (21).