Semiconductor Package Leadframe Anchor Pads for Routing
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Solution Overview
Problem
There is a need for semiconductor packages that accommodate large semiconductor dies while enabling high density circuit routing on printed circuit boards, as existing packages with exposed die pads face challenges in mechanical anchoring, thermal dissipation, and risk of shorting due to the large size of the die pads.
Innovation Solution
The semiconductor package features a leadframe with exposed anchor pads formed on the die pad, which are designed to provide mechanical anchoring and thermal dissipation while allowing for high density circuit routing by segregating leads into sets that extend along the peripheral edge segments, and using a partial etching process to form the anchor pads and shelves, ensuring compatibility with printed circuit boards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large exposed die pad is used to accommodate large semiconductor dies, then mechanical anchoring and thermal dissipation are improved, but circuit routing on the underlying printed circuit board becomes difficult and the risk of shorting increases
Solution Approach 1:
The die pad is segmented into multiple separate anchor pads (first anchor pad, second anchor pad, third anchor pad, fourth anchor pad) positioned at different locations. This segmentation allows circuit routing between the anchor pads on the printed circuit board, enabling high density routing while maintaining mechanical anchoring strength and reducing shorting risk compared to a single large exposed pad.
2Temperature
If a large exposed die pad is used to provide thermal dissipation, then thermal management is improved, but the area available for high density circuit routing on the printed circuit board is reduced
Solution Approach 1:
The large die pad area is divided into multiple smaller anchor pads distributed across the package bottom surface. This segmentation creates multiple discrete thermal pathways to the printed circuit board while opening up routing spaces between the anchor pads, thus maintaining thermal dissipation effectiveness while enabling high density circuit routing.
Solution Approach 2:
The invention transitions from a single large two-dimensional exposed pad to multiple smaller pads distributed in a two-dimensional array, effectively utilizing the package bottom surface area more efficiently. This dimensional redistribution maintains total thermal contact area while creating routing corridors in the spaces between anchor pads.
3Stability of the object's composition
If a single large exposed pad is used for mechanical anchoring, then package stability is improved, but the complexity of leadframe fabrication increases due to the need for precise positioning
Solution Approach 1:
The leadframe fabrication process is simplified by segmenting the die pad into multiple smaller anchor pads that can be formed using standard photolithography and etching patterns. These segmented anchor pads are more easily positioned and aligned during manufacturing compared to a single large pad requiring precise positioning, thus improving ease of manufacture while maintaining package stability through distributed anchoring points.
Data Source
AI summary
A semiconductor package including a leadframe which has one or more anchor pads formed on and/or defined by the die pad thereof. Such anchor pad(s) may be provided in any one of a multiplicity of different pad shapes, and are adapted to satisfy the required mechanical anchoring and thermal dissipation thresholds for the package, while still enabling high density circuit routing on the printed circuit board under the package. The leadframe of the semiconductor package further includes a plurality of leads which are segregated into at least two sets, with the leads of each set extending along and in spaced relation to respective ones of the peripheral edge segments defined by the die pad. 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 of each set by conductive wires. The semiconductor die, the wires, and portions of the die pad and leads are encapsulated by a package body, the bottom surfaces of the anchor pads of the die pad and the bottom surfaces of the leads being exposed in or on a common exterior surface of the package body.