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US 5,396,702 AGranted
Method for forming solder bumps on a substrate using an electrodeposition technique
AssigneeAT&T Corp.
InventorMindaugas F. Dautartas
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Abstract
Solder bumps are electrodeposited onto a substrate with carefully controlled heights by forming patterned conductors on an substrate, depositing and patterning a layer of material, such as titanium that is easily oxidized, and electrodepositing the solder bumps. The solder does not deposit on the titanium. Solder bumps of uniform height are obtained because the titanium layer acts as part of the electrical circuit during electrodeposition.
Claims9
A method of forming solder bumps on a substrate comprising the steps of:
- forming patterned conductors on an insulating substrate;
- blanket depositing a layer of a conducting material on said patterned conductors, said material having a surface on which electrodeposition will not occur;
- removing selected portions of said conducting material to expose selected portions of said patterned conductors;
- and
- electrodepositing material on said selected portions to form solder bumps thereon, said electrodepositing step including electrical contact to said conducting material.
2 more elements
Dependencies are inferred from the claim text.