# US 2014/0190728 A1 · Circuit board and method for manufacturing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0190728 A1 - Document ID: US20140190728A1 - Status: Published application - Kind: A1 - Application number: 13/831,291 - Filed: 2013-03-14 - Published: 2014-07-10 - Earliest claimed: 2013-01-07 - Assignees: Ecocera Optronics Co., Ltd. - Applicants: Ecocera Optronics Co., Ltd. - Inventors: Cheng-Feng Chou; Hung-Pin Lee; Tzu-Yuan Lin - Web page: https://patentgrep.com/patent/US20140190728A1 ## CPC - H05K 3/0029: {of inorganic insulating material} - H05K 3/002: {by liquid chemical etching} - H05K 1/0306: {Inorganic insulating substrates, e.g. ceramic, glass} - H05K 3/42: Plated through-holes {or plated via connections} - H05K 2201/09854: Hole or via having special cross-section, e.g. elliptical - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract The invention provides a method for manufacturing a circuit board comprising the steps of: (a) forming a through hole in a substrate; (b) providing a photo resist to cover a predetermined area adjacent to the through hole on a first surface and a second surface opposite to the first surface of the substrate; and (c) performing an etching process to make the through hole has a shape of dumbbell. ## Claims ### Claim 1 A method for manufacturing a circuit board, comprising steps of: (a) forming a through hole in a substrate having a first surface and a second surface opposite to the first surface, wherein the through hole includes a first part adjacent to the first surface, a second part adjacent to the second surface and a third part located between the first part and the second part; (b) providing a photo resist to cover a predetermined area adjacent to the through hole on the first surface and the second surface of the substrate to expose a part of area of the first surface adjacent to the first part and a part of area of the second surface adjacent to the second part; and (c) performing an etching process to make the diameters of the first part and the second part of the through hole get narrower toward the third part. ### Claim 2 (depends on 1) The method for manufacturing a circuit board of claim 1, further comprising a clean process for the substrate before step (c). ### Claim 3 (depends on 2) The method for manufacturing a circuit board of claim 2, wherein the clean process includes a step of cleaning the substrate by ultrasonic vibration. ### Claim 4 (depends on 2) The method for manufacturing a circuit board of claim 2, wherein the clean process is performed for 5-10 minutes. ### Claim 5 (depends on 1) The method for manufacturing a circuit board of claim 1, wherein the etching process of step (c) uses an etching solution including 50-70 wt % H3PO4, 10-20 wt % HNO3, 10-20 wt % CH3COOH and 5-10 wt % deionized water. ### Claim 6 (depends on 1) The method for manufacturing a circuit board of claim 1, wherein the etching process of step (c) is performed by immersing the substrate into an etching solution with a temperature of 50-70° C. for 0.5-1 hour. ### Claim 7 (depends on 1) The method for manufacturing a circuit board of claim 1, wherein the through hole of step (a) may be formed by mechanical drilling or laser drilling. ### Claim 8 (depends on 1) The method for manufacturing a circuit board of claim 1, wherein the third part of the through hole has substantially the same diameter. ### Claim 9 (depends on 1) The method for manufacturing a circuit board of claim 1, further comprising filling a conductive material in the through hole to form a conductive pillar by an electroplating process after step (c). ### Claim 10 (depends on 1) The method for manufacturing a circuit board of claim 1, wherein an inner wall of the through hole has a surface roughness (Ra) of 0.3-0.4 μm after step (c). ### Claim 11 (depends on 11) The method for manufacturing a circuit board of claim 11, wherein the through hole has a largest diameter of 60-100 μm after step (c). ### Claim 12 (depends on 11) The method for manufacturing a circuit board of claim 11, wherein the through hole has a diameter at the central part less 20-30 μm than the largest diameter. ### Claim 13 A circuit board, comprising: a substrate having a first surface and a second surface opposite to the first surface; and a through hole formed in the substrate, wherein the through hole has a diameter getting narrower toward a central part of the through hole from the first and the second surfaces of the substrate, and an inner wall of the through hole has a surface roughness (Ra) of 0.3-0.4 μm. ### Claim 14 (depends on 13) The circuit board of claim 13, wherein the through hole has a largest diameter of 60-100 μm. ### Claim 15 (depends on 14) The circuit board of claim 14, wherein the through hole has a diameter at the central part less 20-30 μm than the largest diameter. ### Claim 16 (depends on 13) The circuit board of claim 13, wherein the central part of the through hole has substantially the same diameter. ### Claim 17 (depends on 13) The circuit board of claim 13, wherein the substrate includes one of a ceramic subs and a metal substrate. ### Claim 18 (depends on 13) The circuit board of claim 13, being a heat dissipative substrate for a light emitting device.