Leadframe Support Member Etching for Multi-Terminal IC Packages
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Solution Overview
Problem
The existing semiconductor package manufacturing process requires multiple etching steps to create leadframes with complex features, leading to increased complexity, accuracy issues, and the need for thicker copper substrates, which are costly and inefficient.
Innovation Solution
A semiconductor package design featuring a die attach pad surrounded by multiple sets of contact pads, with a groove that circumscribes the first row of contact pads, allowing for fewer etching steps by using a support member that is etched away to isolate the contact pads, and optionally filled with epoxy, reducing the number of processing steps and maintaining a planar bottom surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple etching steps are used to create complex leadframe features, then manufacturing precision is improved, but device complexity and production cost increase
Solution Approach 1:
The leadframe is segmented into distinct functional regions: a support member region that provides structural support and is etched away, and contact pad regions that remain. This segmentation allows complex multi-row leadframe structures to be created through a single etching step by defining different etch resistance properties in different regions, rather than requiring multiple sequential etching steps to create each feature individually.
Solution Approach 2:
The support member is designed with etch resistance properties that allow it to be selectively removed in a single etching step after the contact pads are formed. This preliminary structuring of the leadframe with differentiated etch resistance enables the complex multi-row contact pad pattern to be established before the support member removal, achieving high precision features without multiple etching cycles.
2Manufacturing precision
If multiple etching steps are used to create complex leadframe features, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The leadframe is segmented into distinct functional regions: a support member region that provides structural support and is etched away, and contact pad regions that remain. This segmentation allows complex multi-row leadframe structures to be created through a single etching step by defining different etch resistance properties in different regions, rather than requiring multiple sequential etching steps to create each feature individually.
Solution Approach 2:
Multiple functions are merged into a single etching step: the formation of the multi-row contact pad pattern, the definition of the support member boundaries, and the creation of electrical isolation between contact rows are all achieved simultaneously through one etching process, rather than requiring separate steps for each function.
3Strength
If thicker copper substrates are used to support complex leadframe features, then structural strength is improved, but manufacturing cost increases
Solution Approach 1:
The leadframe is segmented into distinct functional regions: a support member region that provides structural support and is etched away, and contact pad regions that remain. This segmentation allows complex multi-row leadframe structures to be created through a single etching step by defining different etch resistance properties in different regions, rather than requiring multiple sequential etching steps to create each feature individually.
Solution Approach 2:
The support member is extracted from the final product by selectively etching it away after the contact pads are formed. This extraction allows the use of thinner substrates because the support function is temporary—providing structural integrity only during the manufacturing process—and is removed afterward, eliminating the need for permanently thick substrates to support complex features.
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 reduces the number of etching steps required, lowers production costs, and improves manufacturing efficiency by simplifying the process while maintaining high-density multi-row leadframes and semiconductor packages.
Implementation Method 1
the assembly is submerged in an etching solution until the portions 103A, 103B, and 103C are sacrificed, electrically isolating the contacts 103
Data Source
AI summary
A semiconductor package comprises a die attach pad and a support member at least partially circumscribing it. Several sets of contact pads are attached to the support member. The support member is able to be etched away thereby electrically isolating the contact pads. A method for making a leadframe and subsequently a semiconductor package comprises partially etching desired features into a copper substrate, and then through etching the substrate to form the support member and several sets of contact pads. Die attach, wirebonding and molding follow. The support member is etched away, electrically isolating the contact pads and leaving a groove in the bottom of the package. The groove is able to be filled with epoxy or mold compound.