Claims
- 1. A method for chemically milling aluminum from copper-aluminum-copper tri-metal layers, the method comprising the steps of:providing a tri-metal laminate having layers of copper-aluminum-copper having copper circuit patterns present on opposing surfaces of an aluminum foil, and contacting the tri-metal laminate with an etchant comprising an aqueous solution of: (1) 60 to 500 g/l base selected from the group consisting of sodium hydroxide, potassium hydroxide, and mixtures thereof; and (2) 30 to 500 g/l of a salt selected from the group consisting of nitrite salt, borate salt, bromate salt, and mixtures thereof at a temperature of 25 to 95° C. for a time sufficient to selectively remove a desired amount of the aluminum layer and form a electronic circuitry which contains multiple conductive copper circuit layers.
- 2. The method according to claim 1 wherein said is a salt of a metal selected from the group consisting of sodium, potassium, iron, manganese, zinc, lithium, silver, calcium, ammonium, cobalt, copper, aluminum, mercury, thorium, barium, guanidine, lead, cerium, bismuth, zirconium, strontium, cadmium, lanthanum, nickel, and mixtures thereof.
- 3. The method according to claim 1 wherein said etchant is used at a temperature of 40 to 65° C.
- 4. The method according to claim 1 wherein said method comprises dipping said tri-metal laminate in said etchant.
- 5. The method according to claim 1 wherein said method comprises spraying said tri-metal laminate with said etchant.
- 6. The method according to claim 1 wherein said etchant comprises 150 to 250 g/l of said base.
- 7. The method according to claim 1 wherein said etchant comprises 40 to 160 g/l of said salt.
- 8. The method according to claim 1 wherein said etchant is used at a temperature of 45-55° C.
- 9. A method for chemically milling aluminum from copper-aluminum layers, the method comprising the steps of:providing a metal laminate of copper-aluminum having copper circuit patterns present on an aluminum foil, and contacting the metal laminate with an etchant comprising an aqueous etching solution of: (1) 60 to 500 g/l of a base selected from the group consisting of sodium hydroxide, potassium hydroxide, and mixtures thereof; and (2) 30 to 500 g/l of a salt selected from the group consisting of nitrite salt, borate salt, bromate salt, and mixtures thereof at a temperature of 25 and 95° C. for a time sufficient to remove a desired amount of the aluminum layer and form a circuit board which contains a conductive copper circuit layer.
Parent Case Info
Reference is made to related U.S. patent application Ser. No. 08/955,449 filed Dec. 22, 1997 and entitled “ETCHING TRI-METAL LAYERS TO FORM ELECTRONIC CIRCUITS USING AQUEOUS ALKALINE SOLUTIONS INCLUDING NITRATES”, being commonly assigned herewith.
US Referenced Citations (10)
Foreign Referenced Citations (5)
Number |
Date |
Country |
34 05 437 |
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DE |
233 592 |
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DE |
2 195 701 |
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FR |
913 343 |
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GB |
361261484A |
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JP |
Non-Patent Literature Citations (1)
Entry |
WERNICK et al., “The Surface Treatment and Finishing of Aluminum and its Alloys”, Finishing Publications Ltd., 1987, pp. 190-219.* |