Lead Frame Manufacturing via Patterned Conductive Mask Etching
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Solution Overview
Problem
The existing semiconductor packaging methods, such as those described in US 2011/0267789, require the removal of a conductive carrier by chemical etching, increasing complexity and costs due to the additional process step.
Innovation Solution
A method of manufacturing a lead frame involves providing an electrically-conductive base material with patterned conductive layers on both sides, etching one side to form partially-etched portions, filling with non-conductive material, and further etching to create separate conductive regions, eliminating the need for a separate photoresist mask and reducing process complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conductive carrier is used to support metal layers and reduce separation between pads, then the density of electrical interconnections is improved, but the fabrication process complexity increases due to the need for chemical etching to remove the carrier
Solution Approach 1:
The patent extracts and eliminates the conductive carrier from the fabrication process entirely. Instead of using a separate carrier that needs to be removed by chemical etching, the lead frame itself serves as the supporting structure from the beginning, integrating the carrier function into the final product and eliminating the need for carrier removal steps.
Solution Approach 2:
The patent merges the function of the conductive carrier with the lead frame structure. The lead frame is designed to provide both the electrical interconnection function and the mechanical support function that was previously separated into distinct components (carrier + metal layers), thereby simplifying the overall fabrication process.
2Manufacturing precision
If additional process steps are introduced to achieve higher density electrical connections, then the interconnection density is improved, but the manufacturing cost increases
Solution Approach 1:
The patent removes the additional process step of chemical etching for carrier removal. By designing the lead frame to serve as its own carrier, the invention eliminates the need for post-encapsulation etching processes, thereby reducing manufacturing complexity and cost while maintaining high interconnection density.
Solution Approach 2:
The lead frame is pre-configured with the appropriate pattern and structure before encapsulation, eliminating the need for subsequent carrier removal steps. The design anticipates the final configuration requirements, allowing direct encapsulation without additional processing steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the density of electrical interconnections and improves package reliability by reducing the need for additional processing steps and materials, thereby simplifying and cost-effectively increasing the density of electrical connections between semiconductor dies and lead frames.
Implementation Method 1
the patterned conductive layer on the first planar side of the base material could serve as a mask for the later step of etching the exposed portions of the first planar side of the base material
Implementation Method 2
the filling material fills spaces inside the partially-etched portions on the second planar side of the base material to form adjacent portions of the filling material and a plurality of conductive portions
Data Source
AI summary
A method of manufacturing a lead frame, comprising the steps of: providing an electrically-conductive base material having first and second planar sides; forming a patterned conductive layer on the first planar side of the base material; etching the second planar side of the base material at portions with respect to exposed portions on the first planar side of the base material comprising the patterned conductive layer, to form partially-etched portions on the second planar side of the base material; providing a non-conductive filling material over the second planar side of the base material, wherein the filling material fills spaces inside the partially-etched portions on the second planar side of the base material to form adjacent portions of the filling material and a plurality of conductive portions on the second planar side of the base material; and etching the exposed portions of the first planar side of the base material comprising the patterned conductive layer to form partially-etched portions on the first planar side of the base material that combine with the partially-etched portions on the second planar side of the base material to thereby form a plurality of separate conductive regions on the first planar side of the base material, each conductive region being electrically conductive with at least a respective one of the plurality of conductive portions on the second planar side of the base material.