Stamped Lead Frame Features for Semiconductor Package Interlocking
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Solution Overview
Problem
Conventional semiconductor device package fabrication processes face challenges with the complexity and cost associated with the partial etching step, which requires accurate patterning and mask removal, leading to difficulties in achieving precise and repeatable results.
Innovation Solution
The use of stamping to form features on the lead frame, such as chamfered cross-sectional profiles on pins and diepads, along with selective electroplating and brown oxide guard bands, to enhance mechanical interlocking and reduce the need for partial etching, facilitating the fabrication of semiconductor device packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If partial etching process is used to form features on lead frame, then mechanical interlocking is achieved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent replaces the chemical etching process with a mechanical stamping process to form features on the lead frame. The stamping process uses physical deformation through a stamping tool to create recesses and protrusions, eliminating the need for chemical masks and etching solutions, thereby reducing manufacturing complexity while achieving the same mechanical interlocking function.
Solution Approach 2:
The patent changes the manufacturing parameter from chemical etching to mechanical stamping. This parameter change transforms the process from a multi-step chemical procedure requiring precise mask patterning to a single-step mechanical deformation process, significantly simplifying the manufacturing process while maintaining the ability to create complex geometric features for mechanical interlocking.
2Strength
If partial etching process is used to form features on lead frame, then mechanical interlocking is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the chemical etching process with a mechanical stamping process to form features on the lead frame. The stamping process uses physical deformation through a stamping tool to create recesses and protrusions, eliminating the need for chemical masks and etching solutions, thereby reducing manufacturing complexity while achieving the same mechanical interlocking function.
Solution Approach 2:
The stamping tool used in the invention is a simple, durable mechanical component that can be reused multiple times without significant degradation. This replaces the consumable chemical masks and etching solutions required in the conventional process, reducing ongoing material costs and waste disposal expenses associated with chemical etching.
3Strength
If partial etching process is used to form features on lead frame, then mechanical interlocking is achieved, but manufacturing precision and repeatability become difficult to achieve
Solution Approach 1:
The patent replaces the chemical etching process with a mechanical stamping process to form features on the lead frame. The stamping process uses physical deformation through a stamping tool to create recesses and protrusions, eliminating the need for chemical masks and etching solutions, thereby reducing manufacturing complexity while achieving the same mechanical interlocking function.
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 simplifies the manufacturing process by eliminating the need for partial etching, reducing costs, and improving the mechanical interlocking of the lead frame within the package body, while maintaining or enhancing the performance of the semiconductor device package.
Implementation Method 1
portions of the lead frame such as pins are moved out of the horizontal plane of a diepad by stamping. In certain embodiments, a complex cross-sectional profile, such as chamfered, may be imparted to portions of the pins and/or diepad by stamping
Implementation Method 2
Other techniques such as selective electroplating and/or formation of a brown oxide guard band to limit spreading of adhesive material during die attach
Implementation Method 3
formation of a brown oxide guard band to limit spreading of adhesive material during die attach
Data Source
AI summary
Embodiments of the present invention relate to the use of stamping to form features on a lead frame of a semiconductor device package. In one embodiment, portions of the lead frame such as pins are moved out of the horizontal plane of a diepad by stamping. In certain embodiments, indentations or a complex cross-sectional profile, such as chamfered, may be imparted to portions of the pins and/or diepad by stamping. The complexity offered by such a stamped cross-sectional profile serves to enhance mechanical interlocking of the lead frame within the plastic molding of the package body. Other techniques such as selective electroplating and/or formation of a brown oxide guard band to limit spreading of adhesive material during die attach, may be employed alone or in combination to facilitate fabrication of a package having such stamped features.