| 摘要 |
<p>A process is provided for electrodepositing a covering layer of lead-tin on the surface of a bearing structure formed by co-electrodepositing lead, copper and tin which process comprises providing a metallic substrate; placing said metallic substrate in an electroplating bath containing lead ions, tin ions and copper ions; passing electrical current through said bath to deposit a layer of lead-tin-copper on the surface of said substrate; removing said co-plated substrate from said bath, subjecting said so-plated substrate; to an aqueous rinsing medium to remove electrolyte drag-out from said plating bath from the said plated substrate; bringing the resulting aqueous rinsing medium into contact with a solid metal selected from the group consisting of lead, tin and alloys thereof for a period of time sufficient to cause copper ions in said medium to be replaced by ions of said metal and said copper ions to deposit as copper metal on the remainder of the undissolved lead, tin or lead-tin alloy, which is in contact with the rinsing medium, placing said rinsed substrate in an electroplating bath which is essentially devoid of copper ion and which contains both lead ions and tin ions; and passing electrical current through said electroplating bath to deposit a layer of lead-tin on the surface of said substrate.</p> |
