Lead Frame Fabrication via Etched Isolated Conductive Regions
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Solution Overview
Problem
The existing semiconductor packaging methods, such as 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 lead frame is fabricated using an electrically-conductive base material with conductive contact points and a non-conductive filling material, where the second planar side is etched to expose a pattern of the filling material, forming isolated conductive regions connected to the contact points, eliminating the need for a conductive carrier and enhancing electrical interconnection density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conductive carrier is used to support metal layers and reduce separation between bond pads and die-attach barriers, then the density of electrical interconnections is increased, but an additional process step of chemical etching is required to remove the carrier
Solution Approach 1:
The patent extracts and eliminates the conductive carrier from the semiconductor package structure. Instead of using a separate carrier that needs to be removed, the lead frame itself is designed with integrated conductive regions that directly provide the electrical interconnection function, thereby removing the need for the additional chemical etching process step.
Solution Approach 2:
The patent merges the functions of the conductive carrier and the lead frame into a single integrated structure. The lead frame's second surface is etched to form conductive regions that directly serve as bond pads and die-attach barriers, combining the support function and electrical interconnection function into one component.
2Manufacturing precision
If a conductive carrier is used to support metal layers during fabrication, then electrical interconnection density can be increased, but the number of fabrication process steps increases
Solution Approach 1:
The conductive carrier is extracted from the fabrication process. The lead frame is directly etched to form conductive regions that serve as bond pads and die-attach barriers, eliminating the need for carrier-based fabrication and the subsequent carrier removal step, thereby improving fabrication efficiency.
Solution Approach 2:
The conductive regions are formed directly on the lead frame surface through etching before subsequent packaging steps. This preliminary formation of electrical interconnection structures eliminates the need for later carrier removal and rework, streamlining the overall fabrication process.
3Ease of manufacture
If chemical etching is used to remove a conductive carrier, then the carrier can be eliminated from the final structure, but additional process steps and costs are incurred
Solution Approach 1:
The conductive carrier is completely extracted from the process. Instead of adding a carrier and then removing it through chemical etching, the invention uses the lead frame itself with etched conductive regions to provide all necessary electrical interconnection functions, eliminating both the addition and removal steps.
Solution Approach 2:
Instead of the conventional approach of adding a carrier and then removing it, the invention inverts the logic by directly forming the conductive structures on the lead frame surface through etching, eliminating the need for any carrier material to be added or removed.
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 method simplifies the semiconductor packaging process by reducing the need for chemical etching, lowering costs, and increasing the density of electrical connections between semiconductor dies and lead frames, thereby reducing the form factor of electronic packages.
Implementation Method 1
etching the second planar side of the base material to expose a pattern of the filling material from the second planar side of the base material
Data Source
AI summary
Disclosed is a method of manufacturing a lead frame, which comprises the steps of: providing an electrically-conductive base material having first and second planar sides; forming a plurality of conductive contact points on the first planar side of the base material; providing a non-conductive filling material over the first planar side of the base material so that the filling material fills spaces in-between the plurality of contact points to a form a layer comprising the filling material and the plurality of contact points; and etching the second planar side of the base material to expose a pattern of the filling material from the second planar side of the base material and to thereby form a plurality of isolated conductive regions on the second planar side of the base material, each isolated conductive region being connected with at least a respective one of the plurality of contact points on the first planar side of the base material. A lead frame structure is also disclosed.