Plating Method To Reduce Or Eliminate Voids In Solder Applied Without Flux
AssigneeHutchinson Technology Incorporated
InventorsDouglas P. Riemer, Peter F. Ladwig
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Abstract
A method of plating a copper substrate with gold that reduces or eliminates the presence of microvoids at the interface of the gold/copper substrate is described. Suitably, live entry of the substrate into the plating bath is performed with application of external current to the bath such that no portion of the substrate is exposed to the bath for more than one second without the application of the external current. Increase of the applied current for gold strike to the mass-transfer-limit for gold reduction accomplishes the full measure of improvement in eliminating microvoids.
Claims18
A method of plating at least one metal selected from the group 10 and group 11 metal elements of the Periodic Table on a copper substrate comprising:
- vertically lowering the substrate into a bath containing the at least one metal;
- applying an external current through the bath as soon as the substrate is wetted by the bath.
A method of eliminating microvoids formed in a solder joint made over a gold plating on a copper substrate, the method comprising:
- applying an external current sufficient to plate a gold strike onto the substrate within one second of the substrate contacting a plating bath comprising gold, wherein the external current density is 2-10 times greater than a current sufficient to form a gold plating on the substrate.
An electroplating method comprising:
- a. providing a metal substrate upon which it is desired to electroplate a metal plating;
- b. providing a plating bath containing the metal to be plated in solution;
- c. contacting the substrate with the plating bath;
- d. applying an external electrical current through the plating bath as soon as the substrate contacts the bath;
- and
- e. increasing the external electrical current to the maximum mass-transfer-limit once the substrate has been wet by the plating bath.
Dependencies are inferred from the claim text.