Shielded Semiconductor Device Lead Frame Vertical Strip
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Solution Overview
Problem
Conventional semiconductor device packaging lacks effective and cost-efficient electromagnetic interference (EMI) and radio frequency interference (RFI) shielding, particularly for smaller semiconductor dies, as traditional metallic enclosures increase package size and require additional soldering steps, which can harm the device.
Innovation Solution
A semiconductor device with a lead frame featuring a bendable vertical strip that connects to a package lid, providing EMI and RFI shielding, where the lead frame includes a die receiving area, perpendicular leads, and a molding compound encapsulating the die and electrical connections, with the lid formed over the top surface to contact the distal end of the vertical strip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive metallic enclosure is used for EMI and RFI shielding, then shielding effectiveness is improved, but package size increases and manufacturing complexity increases
Solution Approach 1:
The patent combines the shielding function with the existing package lid structure. The metallic lid that normally serves as a protective cover is configured to provide EMI and RFI shielding by establishing electrical connection between its inner and outer surfaces through conductive material in the cavity, eliminating the need for a separate shielding enclosure.
Solution Approach 2:
The package lid is given multiple functions: it serves both as a protective cover and as an EMI/RFI shield. By making the lid conductive through the addition of conductive material in the cavity, a single component performs both mechanical protection and electromagnetic shielding functions.
2Reliability
If a conductive metallic enclosure is used for EMI and RFI shielding, then shielding effectiveness is improved, but manufacturing complexity increases due to additional soldering steps
Solution Approach 1:
The patent merges the shielding function into the existing package structure. The conductive material is integrated into the cavity during the molding process, and the metallic lid is connected to this conductive material, eliminating the need for separate shielding components and their associated assembly steps.
Solution Approach 2:
The conductive material is placed in the cavity before molding, and the metallic lid is designed to make electrical contact with this conductive material. This preliminary configuration ensures shielding effectiveness is built into the structure during manufacturing, avoiding the need for additional soldering or assembly steps after packaging.
3Reliability
If a metal cap is placed over the semiconductor device, then EMI and RFI shielding is provided, but the solution is only applicable to large die sizes
Solution Approach 1:
The package lid structure is designed to provide shielding functionality that is independent of die size. The cavity and conductive material configuration work effectively for various die dimensions, making the shielding solution universally applicable to different semiconductor device sizes and package types.
Solution Approach 2:
The conductive material is strategically placed in the cavity to provide shielding effectiveness. The configuration of the conductive material and its connection to the metallic lid creates localized electric field distribution that effectively shields the device regardless of the die size, adapting to different package dimensions.
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 solution offers a cost-effective, compact EMI and RFI shielding method that can be applied to various package sizes without the need for additional soldering, protecting semiconductor devices from interference while maintaining device integrity.
Implementation Method 1
The lid provides EMI and RFI shielding
Implementation Method 2
The conductive material in the cavity establishes an electrical connection between inner and outer surfaces of the metallic lid
Data Source
AI summary
A shielded semiconductor device is assembled using a lead frame having a die receiving area, leads disposed around the die receiving area, and a bendable strip formed in the die receiving area. Each lead has an inner lead end that is spaced from but near to one of the sides of the die receiving area and an outer lead end that is distal to that side of the die receiving area. An IC die is attached to the die receiving area and electrically connected to the inner lead ends of the leads. An encapsulant is formed over the die and the electrical connections and forms a body. The strip is bent to extend vertically to a top side of the body. A lid is formed on the top side of the body and is in contact with a distal end of the vertical strip.