Leadframe with Combined Leads and Lands for High I/O Density
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Solution Overview
Problem
Conventional semiconductor devices with leadframes are inadequate for meeting the increasing demand for smaller, lighter, and high-capacity semiconductor packages with exposed pads, as they fail to provide sufficient I/O with reduced size and weight.
Innovation Solution
A semiconductor device design featuring a leadframe with a combination of leads and lands, where the lands are arranged in a specific pattern and exposed within the package body, fabricated using standard forming techniques such as sawing, punching, or etching to enhance electrical isolation and mechanical interlock, while protecting the semiconductor die from moisture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional leadframe structures are used, then manufacturing simplicity is maintained, but I/O capacity is insufficient and package size cannot be reduced
Solution Approach 1:
The leadframe structure is segmented into multiple functional zones: traditional leads extending from the package body, and lands exposed within the package body in a grid array pattern. This segmentation allows simultaneous provision of multiple I/O connections without increasing overall package volume, as lands utilize the interior package space for electrical connections.
Solution Approach 2:
The invention transitions from conventional two-dimensional lead arrangements on the package perimeter to a three-dimensional configuration by exposing lands within the package body. This allows I/O connections to be made in multiple spatial dimensions, increasing I/O capacity without proportionally increasing package footprint.
2Quantity of substance
If more leads are added to increase I/O capacity, then electrical connectivity improves, but package weight increases
Solution Approach 1:
The invention merges the functions of leads and lands into a single leadframe structure. Lands are formed by etching or removing portions of the leadframe material, combining the support function of leads with the connection function of lands. This integration achieves high I/O capacity using the same material mass, preventing weight increase.
3Quantity of substance
If lands are exposed within the package body, then electrical connectivity and I/O capacity increase, but manufacturing complexity increases
Solution Approach 1:
The invention extracts specific portions of the leadframe material through etching or punching to form lands with different electrical connectivity. This extraction creates the land grid array pattern within the package body, enabling increased I/O capacity. The process uses standard PCB fabrication techniques, adding minimal complexity to the manufacturing flow.
Solution Approach 2:
Different regions of the leadframe are given different local qualities: some regions form continuous leads extending from the package, while other regions are etched to create discrete lands exposed within the package body. This local differentiation allows optimization of electrical connectivity in different areas without requiring complete redesign of the entire leadframe structure.
4Ease of manufacture
If standard forming techniques are used for leadframe fabrication, then manufacturing cost is reduced, but electrical isolation between leads is insufficient
Solution Approach 1:
The invention converts what would normally be a harmful short circuit condition into a beneficial feature by intentionally creating lands with different electrical connectivity through controlled etching. The etching process, which removes material and could create defects, is instead used to define distinct electrical zones. This converts a potential reliability issue into a mechanism for achieving both cost-effective manufacturing and proper electrical isolation.
Data Source
AI summary
In one embodiment, a semiconductor device includes a die pad defining multiple peripheral edge segments. In addition, the semiconductor device includes a plurality of leads and lands which are provided in a prescribed arrangement. Connected to the top surface of the die pad is at least one semiconductor die which is electrically connected to at least some of the leads and lands. At least portions of the die pad, the leads, the lands, and the semiconductor die are encapsulated by the package body, with at least portions of the bottom surfaces of the die pad and the lands being exposed in a common exterior surface of the package body.