Two pass process for producing a fine pitch lead frame by etching
AssigneeTexas Instruments Incorporated
InventorsGijsbert W. Lokhorst, Robert M. Fritzsche, Ronald B. Wheelock
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Abstract
A method of fabricating a lead frame. The method includes providing an electrically conductive layer having a pair of opposing major surfaces. A pattern is etched in the layer extending partially through the layer to form cavities with sidewalls in the layer. A patterned mask is provided on the etched layer including masking of the sidewalls. The layer is again etched within the cavities. The patterned mask is preferably a liquid photo resist and the electrically conductive layer is preferably one of a copper or copper-based material or ALLOY 42. The etch can take place from both major surfaces.
Claims19
A method of fabricating a lead frame which comprises the steps of:
- (a) providing an electrically conductive layer having a pair of opposing major surfaces;
- (b) first etching a pattern in said electrically conductive layer extending partially through said electrically conductive layer to form cavities with sidewalls in said electrically conductive layer;
- (c) providing a patterned mask on said electrically conductive layer, said patterned mask masking said sidewalls;
- and
- (d) then again etching said layer within said cavities, said sidewalls not being etched due to said patterned mask masking said sidewalls in said cavities.
Dependencies are inferred from the claim text.