| 摘要 |
THE PROBLEM IN FORMING SOLDERABLE AND BONDABLE LAYERS ON PRINTED CIRCUIT BOARDS IS THAT THE SURFACES TARNISH AFTER STORAGE OF THE BOARDS PRIOR TO FURTHER PROCESSING (MOUNTING OF THE ELECTRICAL COMPONENTS), THUS AFFECTING SOLDERABILITY AND BONDABILITY. IN ORDER TO OVERCOME THIS PROBLEM IT IS SUGGESTED TO DEPOSIT, IN A FIRST METHOD STEP, A FIRST METAL WHICH IS MORE NOBLE THAN COPPER TO THE PRINTED CIRCUIT BOARD AND TO PLATE SILVER IN A SECOND METHOD STEP WITH THE PROVISO THAT THE FIRST METAL BE DEPOSITED AT A RATE THAT IS AT MOST HALF THE RATE OF PLATING OF SILVER IN THE SECOND METHOD STEP WHEN THE FIRST METAL IS SILVER.
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