Method of forming lead-free bump interconnections
AssigneeAdvanced Interconnect Technology Ltd.
InventorsEdwin Wai Ming Cheung, Zaheed Sadrudin Karim
Life of this patent
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Abstract
A method of forming solder bumps on a chip or wafer for flip-chip applications comprises the steps of providing a chip or wafer having a plurality of metal bonds pads which provide electrical connection to the chip or wafer, and applying a solder bump comprising pure tin or a tin alloy selected from tin-copper, tin-silver, tin-bismuth or tin-silver-copper by an electroplating technique, and melting the solder bumps by heating to a temperature above the bump melting point to effect reflow.
Claims11
A method of forming solder bumps on a chip or wafer for flip-chip applications, comprising the steps of providing a chip or wafer having a plurality of metal bonds pads which provide electrical connection to the chip or wafer, and applying a solder bump comprising tin-copper alloy having less than 2% by weight copper, the balance being tin, by an electroplating technique, and melting the solder bumps by heating to a temperature above the bump melting point to effect reflow.
A method for forming solder bumps on a chip or wafer for flip-chip applications comprising the steps of:
- (a) providing a chip or wafer having a passivation layer and a plurality of exposed metallic bond pads;
- (b) applying at least one solder-wettable metal layer to the bond pad;
- (c) applying a photosensitive layer to the chip or wafer having openings at the portions of the bond pads;
- (d) applying a solder comprising tin-copper alloy having less than 2% by weight copper with the balance being tin by an electroplating technique
- (e) removing the photosensitive layer;
- and
- (f) melting the solder bumps to effect reflow.
Dependencies are inferred from the claim text.