# US 8,784,634 B2 · Electrolytic method for filling holes and cavities with metals > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,784,634 B2 - Document ID: US8784634B2 - Status: Granted - Kind: B2 - Application number: 12/295,513 - Filed: 2007-03-30 - Published: 2009-12-10 - Granted: 2014-07-22 - Earliest claimed: 2006-03-30 - Assignees: Atotech Deutschland GmbH - Applicants: Bert Reents; Bernd Roelfs; Tafadzwa Magaya; Markus Youkhanis; René Wenzel; Soungsoo Kim - Inventors: Bert Reents; Bernd Roelfs; Tafadzwa Magaya; Markus Youkhanis; René Wenzel; Soungsoo Kim - Web page: https://patentgrep.com/patent/US8784634B2 ## CPC - H05K 3/423: {characterised by electroplating method} - C25D 3/38: of copper - C25D 5/18: Electroplating using modulated, pulsed or reversing current - H05K 2201/09563: Metal filled via - H05K 2203/1476: Same or similar kind of process performed in phases, e.g. coarse patterning followed by fine patterning - H05K 2203/1492: Periodical treatments, e.g. pulse plating of through-holes - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR ## Abstract Disclosed is an electroplating method for filling cavities, through holes, blind holes, or micro blind holes of a work piece with metals. According to said method, the work piece containing cavities, through holes, blind holes, or micro blind holes is brought in contact with a metal deposition electrolyte, and a voltage is applied between the work piece and at least one anode such that a current flow is fed to the work piece. The invention method is characterized in that the electrolyte encompasses a redox system. ## Claims ### Claim 1 A galvanic method for filling cavities, blind holes or micro blind holes of a work piece with metals, comprising bringing into contact the work piece containing cavities, blind holes or micro blind holes with a metal deposition electrolyte and applying a voltage between the work piece and at least one anode such that a current flow is fed to the work piece, and wherein the electrolyte contains a Fe(II)/Fe(III) redox system and the Fe(II) ion concentration is contained at at least 1 g/l and the Fe(III) ion concentration is contained at 7-30 g/l, and wherein the metal deposition predominantly occurs in the cavities, blind holes or micro blind holes, rather than at the surface of the work piece; wherein a first voltage is applied between a first side of the work piece and at least one first anode such that a first pulse reverse current is fed to the first side of the work piece, wherein at least one first forward current pulse and at least one first reverse current pulse flow in each cycle of said first pulse reverse current, a second voltage is applied between a second side of the work piece and at least one second anode such that a second pulse reverse current is fed to the second side of the work piece, wherein at least one second forward current pulse and at least one second reverse current pulse flow in each cycle of said second pulse reverse current. ### Claim 2 (depends on 1) A method according to claim 1, wherein the Fe(II) ion concentration is contained at 2-25 g/l and the Fe(III) ion concentration is contained at 7-15 g/l. ### Claim 3 (depends on 2) A method according to claim 2, wherein the Fe(III) ion concentration is contained at 7-9 g/l. ### Claim 4 (depends on 1) A method according to claim 1, wherein the electrolyte contains 15-75 g/l copper, 50-300 g/l H2SO4 and 20-200 mg/l chloride. ### Claim 5 (depends on 1) A method according to claim 1, wherein the Fe(III) ion concentration is contained at 7-8 g/l. ### Claim 6 (depends on 1) A method according to claim 1, wherein the cavities, blind holes or micro blind holes have a maximum height of 3.5 mm. ### Claim 7 (depends on 1) A method according to claim 1, wherein the cavities, blind holes or micro blind holes have a maximum diameter of 1000 μm. ### Claim 8 (depends on 1) A method according to claim 1, wherein the work piece is a circuit board or another electric circuit support in board form. ### Claim 9 (depends on 1) A method according to claim 1, wherein the cavities, blind holes or micro blind holes have a height of 0.05 mm-0.5 mm. ### Claim 10 (depends on 1) A method according to claim 1, wherein the cavities, blind holes or micro blind holes have a diameter of 60 μm-150 μm. ### Claim 11 (depends on 1) A method according to claim 1 wherein the Fe(II) ion concentration is 2-25 g/l, the Fe(III) ion concentration is contained at 7-15 g/l, and the electrolyte further contains 15-75 g/l copper, 50-300 g/l H2SO4 and 20-200 mg/l chloride, and wherein the cavities, blind holes or micro blind holes have a maximum height of 3.5 mm and a maximum diameter of 1000 μm. ### Claim 12 A galvanic method for filling cavities, through holes, blind holes or micro blind holes of a work piece with metals, comprising bringing into contact the work piece containing cavities, through holes, blind holes or micro blind holes with a metal deposition electrolyte and applying a voltage between the work piece and at least one anode such that a current flow is fed to the work piece and a metal deposition completely fills the cavities, through holes, blind holes or micro blind holes, and wherein the electrolyte contains a Fe(II)/Fe(III) redox system and the Fe(II) ion concentration is contained at at least 1 g/l and the Fe(III) ion concentration is contained at 7-30 g/l, and wherein the metal deposition predominantly occurs in the cavities, through holes, blind holes or micro blind holes, rather than at the surface of the work piece, wherein a first voltage is applied between a first side of the work piece and at least one first anode such that a first pulse reverse current is fed to the first side of the work piece, wherein at least one first forward current pulse and at least one first reverse current pulse flow in each cycle of said first pulse reverse current, a second voltage is applied between a second side of the work piece and at least one second anode such that a second pulse reverse current is fed to the second side of the work piece, wherein at least one second forward current pulse and at least one second reverse current pulse flow in each cycle of said second pulse reverse current. ### Claim 13 (depends on 12) A method according to claim 12, wherein the electrolyte contains 15-75 g/l copper, 50-300 g/l H2SO4 and 20-200 mg/l chloride. ### Claim 14 (depends on 12) A method according to claim 12, wherein the current flow in a first step (i) is selected such that a preferred deposition occurs in the center of the through holes and as a result the through holes grow together completely or almost completely, and in a further step (ii) further bringing into contact the work piece with a metal deposition electrolyte and applying a voltage between the work piece and at least one anode is carried out such that a current flow is fed to the work piece, wherein the through holes obtained according to step (i), which are completely or almost completely separated into two halves, are filled by the metal, wherein the current flow according to step (i) is a pulse reverse current and at least one forward current pulse and at least one reverse current pulse occurs in each current cycle and that the current flow according to step (ii) is either a pulse reverse current, a direct current or an alternating current, and wherein in step (i) the ratio of the duration of the at least one forward current pulse to the duration of the at least one reverse current pulse is adjusted to 5-75, the duration of the at least one forward current pulse is adjusted to 5-250 ms and the duration of the at least one reverse current pulse is adjusted to 20 ms at the most; wherein during the carrying out of step (i), the ratio of the peak current density of the forward current pulse to the peak current density of the reverse current pulse is increased or during the carrying out of step (i), the ratio of the duration of the forward current pulse to the duration of the reverse current pulse is lowered. ### Claim 15 (depends on 12) A method according to claim 12, wherein the first current pulse is shifted with respect to the second current pulse by about 180°. ### Claim 16 (depends on 12) A method according to claim 12, wherein the current flow in a first step (i) is selected such that a preferred deposition occurs in the center of the through holes and as a result the through holes grow together completely or almost completely, and in a further step (ii) further bringing into contact the work piece with a metal deposition electrolyte and applying a voltage between the work piece and at least one anode is carried out such that a current flow is fed to the work piece, wherein the through holes obtained according to step (i), which are completely or almost completely separated into two halves, are filled by the metal, wherein the current flow according to step (i) is a pulse reverse current and at least one forward current pulse and at least one reverse current pulse occurs in each current cycle and that the current flow according to step (ii) is either a pulse reverse current, a direct current or an alternating current, and wherein in step (i) the ratio of the duration of the at least one forward current pulse to the duration of the at least one reverse current pulse is adjusted to 5-75, the duration of the at least one forward current pulse is adjusted to 5-250 ms and the duration of the at least one reverse current pulse is adjusted to 20 ms at the most. ### Claim 17 (depends on 16) A method according to claim 16, wherein the metallization steps (i) and (ii) are carried out in the same electrolyte. ### Claim 18 (depends on 16) A method according to claim 16, wherein the ratio of the duration of the at least one forward current pulse to the duration of the at least one reverse current pulse is adjusted to about 20. ### Claim 19 (depends on 16) A method according to claim 16, wherein the duration of the at least one reverse current pulse is adjusted to 1-10 ms. ### Claim 20 (depends on 16) A method according to claim 16, wherein the peak current density of the at least one forward current pulse at the work piece is adjusted to a maximum of 15 A/dm2. ### Claim 21 (depends on 16) A method according to claim 16, wherein the peak current density of the at least one reverse current pulse at the work piece is adjusted to a maximum of 60 A/dm2. ### Claim 22 (depends on 16) A method according to claim 16, wherein the peak current density of the at least one forward current pulse at the work piece is adjusted to a maximum of 1.5-8 A/dm2 in horizontal methods and to a maximum of 2 A/dm2 in vertical methods. ### Claim 23 (depends on 16) A method according to claim 16, wherein the peak current density of the at least one reverse current pulse at the work piece is adjusted to a maximum of 30-50 A/dm2 in horizontal methods and to a maximum of 3-10 A/dm2 in vertical methods. ### Claim 24 (depends on 16) A method according to claim 16 wherein during the carrying out of step (i), the ratio of the peak current density of the forward current pulse to the peak current density of the reverse current pulse is increased. ### Claim 25 (depends on 16) A method according to claim 16 wherein during the carrying out of step (i), the ratio of the duration of the forward current pulse to the duration of the reverse current pulse is lowered.