# US 7,743,494 B2 · Process of fabricating a circuit board > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,743,494 B2 - Document ID: US7743494B2 - Status: Granted - Kind: B2 - Application number: 11/972,671 - Filed: 2008-01-11 - Published: 2009-07-16 - Granted: 2010-06-29 - Earliest claimed: 2008-01-11 - Assignees: PPG Industries Ohio, Inc. - Inventors: Alan E. Wang; Kevin C. Olson; Michael J. Pawlik - Web page: https://patentgrep.com/patent/US7743494B2 ## CPC - H05K 3/429: {Plated through-holes specially for multilayer circuits, e.g. having connections to inner circuit layers} - H05K 3/445: {having insulated holes or insulated via connections through the metal core} - H05K 3/4641: {having integrally laminated metal sheets or special power cores} - H05K 2201/09309: Core having two or more power planes; Capacitive laminate of two power planes - H05K 2203/135: Electrophoretic deposition of insulating material - Y10T 29/49126: Assembling bases - Y10T 29/49165: by forming conductive walled aperture in base - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A process for fabricating a circuit board includes: providing a substrate including a first electrically conductive core having a first insulating coating on a first side and a second insulating coating on a second side, forming an opening in the first and second insulating coatings and the first electrically conductive core, exposing an edge of the conductive core within the opening, and electrodepositing a third insulating material on the exposed edge of the first electrically conductive core. A circuit board fabricated using the process is also provided. ## Claims ### Claim 1 A process for fabricating a circuit board comprising: providing a substrate including a first electrically conductive core having a first insulating coating on a first side and a second insulating coating on a second side; forming an opening in the first and second insulating coatings and the first electrically conductive core, exposing an edge of the conductive core within the opening; using an acid etch comprising an HCl/CuClx/H2O2 mix, where x is 1 or 2 at a pH of about 1.5 to remove a portion of the conductive core to create a recessed edge of the conductive core in a cavity in a wall of the opening; and electrodepositing a third insulating material on the exposed edge of the first electrically conductive core. ### Claim 2 (depends on 1) The process of claim 1, further comprising: reaming the opening. ### Claim 3 (depends on 1) The process of claim 1, wherein the substrate includes a second electrically conductive core, electrically insulated from the first electrically conductive layer, and the process further comprises: filling the opening with a conductive material, wherein the conductive material is electrically insulated from the first conductive core by the third insulating material, and electrically connected to the second electrically conductive layer. ### Claim 4 (depends on 1) The process of claim 1, wherein the third insulating material comprises: a cathodic epoxy. ### Claim 5 (depends on 1) The process of claim 1, wherein the third insulating material comprises: resinous phase dispersed in an aqueous medium, where the resinous phase has a covalently bonded halogen content of at least 1 percent by weight based on total weight of resin solids present in said resinous phase. ### Claim 6 (depends on 1) The process of claim 1, wherein the third insulating material comprises: a water dispersible polymer including a cationic functional group to impart a positive charge. ### Claim 7 (depends on 6) The process of claim 6, wherein the cationic functional group comprises a cationic salt group. ### Claim 8 (depends on 7) The process of claim 7, wherein the cationic salt group comprises a cationic amine salt group. ### Claim 9 (depends on 1) The process of claim 1, wherein the third insulating material comprises: an active hydrogen-containing ionic electrodepositable resin. ### Claim 10 (depends on 9) The process of claim 9, wherein the active hydrogen-containing ionic electrodepositable resin is cationic and capable of deposition on a cathode. ### Claim 11 (depends on 9) The process of claim 9, wherein the active hydrogen-containing ionic electrodepositable resin comprises a cationic salt group-containing polymer. ### Claim 12 (depends on 11) The process of claim 11, wherein the resin is a reaction product of an epoxy functional material with a halogenated phenol followed by reaction of any residual epoxy groups with an amine. ### Claim 13 (depends on 12) The process of claim 12, wherein the reaction product is solubilized with an acid. ### Claim 14 (depends on 9) The process of claim 9, wherein the active hydrogen-containing ionic electrodepositable resin comprises an amine salt group-containing resin. ### Claim 15 (depends on 14) The process of claim 14, wherein the amine salt group-containing resin comprises an acid-solubilized reaction product of polyepoxides and primarily or secondary amines. ### Claim 16 (depends on 9) The process of claim 9, wherein the active hydrogen-containing ionic electrodepositable resin comprises about 10 to about 70 percent by weight of the electrodepositable coating. ### Claim 17 (depends on 1) The process of claim 1, wherein the third insulating material comprises: a resin which cures via transesterification. ### Claim 18 (depends on 17) The process of claim 17, wherein the resin comprises cationic salt groups. ### Claim 19 (depends on 18) The process of claim 18, wherein the resin is formed by solubilizing the film-forming resin with an inorganic or organic acid. ### Claim 20 (depends on 18) The process of claim 18, wherein the resin is formed by solubilizing the film-forming resin with a sulfamic acid. ### Claim 21 (depends on 1) The process of claim 1, wherein the third insulating material comprises: a resin derived from a halogenated compound selected from at least one of a halogenated phenol, or a brominated bisphenol. ### Claim 22 (depends on 21) The process of claim 21, wherein the brominated bisphenol comprises tetrabromobisphenol A. ### Claim 23 (depends on 1) The process of claim 1, wherein the third insulating material comprises: an ionic electrodepositable resin and a curing agent adapted to react with the active hydrogens of the resin. ### Claim 24 (depends on 1) The process of claim 1, wherein the third insulating material further comprises a rheology modifier. ### Claim 25 (depends on 24) The process of claim 24, wherein the rheology modifier comprises a cationic microgel dispersion prepared by dispersing in aqueous medium a mixture of a cationic polyepoxide-amine reaction product which contains amine groups. ### Claim 26 (depends on 25) The process of claim 25, wherein the amine groups comprise primary amine groups, secondary amine groups or mixtures thereof, and a polyepoxide crosslinking agent. ### Claim 27 (depends on 25) The process of claim 25, further comprising: heating the third insulating material to a temperature sufficient to crosslink the third insulating material, thus forming a cationic microgel dispersion. ### Claim 28 (depends on 27) The process of claim 27, wherein the microgel is present in a resinous phase of the third insulating material in an amount ranging from about 1 to about 20 weight percent based on weight of total resin solids. ### Claim 29 (depends on 1) The process of claim 1, wherein the third insulating material comprises a clear resin feed, which includes an active hydrogen-containing ionic electrodepositable resin. ### Claim 30 (depends on 29) The process of claim 29, wherein the resin comprises a film-forming polymer, a curing agent, and a catalyst. ### Claim 31 (depends on 29) The process of claim 29, wherein the resin comprises a substantially pigment-free, one-component composition. ### Claim 32 (depends on 1) The process of claim 1, wherein the third insulating material comprises an aqueous medium including a coalescing solvent. ### Claim 33 (depends on 32) The process of claim 32, wherein the coalescing solvent includes monobutyl or monohexyl ethers of ethylene glycol. ### Claim 34 (depends on 1) The process of claim 1, wherein the third insulating material is applied using a voltage of about 50 and about 500 volts. ### Claim 35 (depends on 1) The process of claim 1, further comprising: curing the third insulating material at temperatures ranging from about 90° to about 300° C. for a period of 1 to 40 minutes. ### Claim 36 (depends on 1) The process of claim 1, wherein the third insulating material has a dielectric constant of no more than about 3.50. ### Claim 37 (depends on 1) The process of claim 1, wherein the opening has a diameter of less than about 200 microns.