Flat Semiconductor Package with Half Molding for Stacking
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Solution Overview
Problem
There is a growing need in high-frequency applications such as hard disk drives and digital television for semiconductor packages with increased functional capacity, particularly in QFP exposed pad packages that can facilitate stacking and higher memory requirements, but existing technologies do not adequately address this need.
Innovation Solution
The development of a semiconductor package with a uniquely configured leadframe that maximizes exposed leads, featuring a planar die paddle with multiple peripheral edge segments and segregated lead rows, where both the bottom and top surfaces of the die paddle and leads are exposed, allowing for enhanced electrical connectivity and stacking capabilities, fabricated using standard low-cost techniques like sawing, punching, or etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional QFP package design is used, then manufacturing cost is low, but functional capacity and stacking capability are insufficient
Solution Approach 1:
The leadframe is segmented into multiple functional zones with leads arranged in concentric rows (first, second, and third rows at different radial distances from the die pad). This segmentation allows different lead groups to serve different functions, enabling increased functional capacity while maintaining a manageable structural organization that supports stacking applications.
Solution Approach 2:
The patent transitions from conventional two-dimensional lead arrangements to a three-dimensional configuration with leads at multiple radial distances and angular positions around the die pad. This dimensional expansion allows more leads to be packed within the same package footprint, increasing functional capacity without proportionally increasing package area.
2Quantity of substance
If more leads are exposed on the package, then electrical connectivity is improved, but manufacturing complexity increases
Solution Approach 1:
The leadframe is pre-configured with leads arranged in specific concentric rows and angular positions before the molding process. This preliminary arrangement allows the molding compound to be applied in a single operation that encapsulates the die and leads while leaving predetermined portions exposed, avoiding the need for subsequent complex exposure operations and simplifying manufacturing.
Solution Approach 2:
The mold cavity design is made universal to accommodate the multi-row lead configuration. The molding process simultaneously performs multiple functions: encapsulating the die, positioning the leads, and creating the exposed lead surfaces all in one operation, thereby reducing manufacturing complexity despite the increased number of exposed leads.
3Adaptability or versatility
If leads are arranged in multiple concentric rows, then functional capacity increases, but leadframe design complexity increases
Solution Approach 1:
The leadframe employs a nested concentric row structure where the first row of leads is at a first radial distance, the second row at a second radial distance, and the third row at a third radial distance from the die pad. This nested arrangement allows leads to be organized in hierarchical layers, maximizing the use of available space around the die pad and enabling stacking capability while maintaining systematic design simplicity.
Data Source
AI summary
In accordance with the present invention, there are provided multiple embodiments of a semiconductor package, each embodiment including a uniquely configured leadframe sized and configured to maximize the available number of exposed leads in the semiconductor package. More particularly, each embodiment of the semiconductor package of the present invention includes a generally planar die paddle defining multiple peripheral edge segments and a plurality of leads, the exposed portions of the bottom surfaces of which are segregated into at least two concentric rows. Connected to the top surface of the die paddle is at least one semiconductor die which is electrically connected to at least some of the leads of each row. At least portions of the die paddle, the leads, and the semiconductor die are encapsulated by a package body, the bottom surfaces of the die paddle and the leads of both rows thereof being exposed in a common exterior surface of the package body. In certain embodiments of the present invention, the top surfaces of at least some of leads of the leadframe are also exposed in an exterior surface of the package body.