| 摘要 |
A PROCESS FOR PLATING TIN OR TIN ALLOY ONTO METAL SUBSTRATES IS DESCRIBED. IN THE PROCESS, A METAL SUBSTRATE IS PLACED IN AN ELECTROPLATING BATH THAT CONTAINS A STANNOUS SULFATE AND AN ORGANIC COMPOUND ADDITIVE IN WHICH THE ORGANIC COMPOUND HAS A HETEROCYCLIC MOIETY IN AN AQUEOUS SOLUTION OF SULFONIC ACID. THE BATH IS THEN SUBJECTED TO PULSE PLATING CONDITIONS THAT PLATE A LAYER OF TINOR TIN ALLOY ONTO THE METAL SUBSTRATE WHEREIN THE TIN IN THE TIN LAYER HAS A GRAIN SIZE OF ABOUT 2 µM TO ABOUT 8 µM. DURING PULSE PLATING, A CURRENT DENSITY OF ABOUT 65 ASF TO ABOUT 250 ASF IS APPLIED TO THE ELECTROPLATING BATH IN A PULSED MANNER, I.E. THE CURRENT IS CYCLED ON AND OFF DURING PLATING. THE DUTY CYCYLE OF THE PULSE IS ABOUT TWENTY-FIVE PERCENT TO ABOUT THIRTY PERCENT. THE DURATION OF THE ON PULSE DURING THE CYCLE IS ABOUT 50 µS TO ABOUT 500 µS.
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