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AssigneeNone recorded
InventorsByoung-Ho Rhee, Dek-Gin Yang, Dong-Gi An, Chul-Min Lee, Tae-Kyu Kwak, Sung-Yong Her, Sung-Wook Chun, Myong-Chul Shin, Sang-Wook Chun
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Disclosed is an aqueous alloy plating solution for surface treatment of a modular PCB. The plating solution comprises 1-30 wt % of an organic acid having at least one sulfonic acid group (—SO3H), 0.1-20 wt % of a complexing agent, 0.1-15 wt % of a thio-compound having at least one —S—, 0.05-5 wt % of a water soluble gold compound, 0.001-1 wt % of a water soluble silver compound and 0.1-10 wt % of a sequestering agent, based upon the weight of the plating solution. According to this invention, all plating properties required for the modular PCB are obtained through a single plating process, instead of the conventional double plating process.
Aqueous electroless plating solution for surface treatment of a modular PCB, comprising 1-30 wt % of an organic acid having at least one sulfonic acid group (—SO3H), 0.1-20 wt % of a complexing agent, 0.1-15 wt % of a thio-compound having at least one —S—, 0.05-5 wt % of a water soluble gold compound, 0.001-1 wt % of a water soluble silver compound and 0.1-10 wt % of a sequestering agent, on the basis of the weight of the plating solution.
Dependencies are inferred from the claim text.
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Reinforcing of the conductive pattern: finish plating of conductors, especially of copper conductors, e.g. for pads or lands
By reduction or substitution, e.g. electroless plating: coating with alloys
Printed circuits
Coating metallic material
Term end not estimated
1. Field of the Invention
The present invention pertains to gold-silver alloy plating solution compositions, applicable for surface treatment of a modular printed circuit board (hereinafter, referred to a modular PCB) for mounting parts. More specifically, the present invention pertains to a gold-silver alloy plating solution, which forms an alloy plated layer comprising 90-99% gold and 1-10% silver by electroless plating a nickel on a pad portion and a tab portion of the modular PCB and then immersion plating the nickel-plated surface of the modular PCB with the gold-silver alloy plating solution.
2. Description of the Prior Art
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a photograph showing a top view of a modular printed circuit board in a strip form.
FIG. 2 is a schematic diagram showing a plating process of the conventional modular printed circuit board.
The present invention is directed to an aqueous electroless gold-silver alloy plating solution, capable of substituting a single plating process for the conventional double plating process comprising a soft gold electroless plating process and a hard gold electroplating process. An alloy plated layer obtained as a gold and silver eutectoid layer can provide solderability to a pad portion for mounting parts, as well as excellent abrasion resistance to a tab portion, respectively, whereby the advantages of the double plating process can be obtained at the same time.
The aqueous electroless gold-silver plating solution according to the present invention comprises an organic acid, a complexing agent, a thio-compound, a water soluble gold compound, a water soluble silver compound and a sequestering agent. A plating principle of the plating solution is briefly described as follows.
Before plating, an electroless nickel plated layer over the pad portion and the tab portion on the modular printed circuit board is formed. Based on the principle in which the organic acid in the plating solution partly dissolves the nickel (Ni) layer and the gold and silver ions complexed by the complexing agent under the aqueous condition are deposited to form a gold-silver alloy layer on the nickel layer by potential difference, the plating process is conducted.