Lead Frame Mesa Structure for Multi-Die Integration
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Solution Overview
Problem
The semiconductor industry faces challenges in integrating multiple power device dies and logic dies in a single package due to mechanical instability of lead frames and the complexity of electrical connections within a small package footprint, as well as spacing constraints for creepage and clearance requirements.
Innovation Solution
A method involving a lead frame with a central metal plate and elevated mesas for mounting semiconductor dies, forming electrical interconnections, and encapsulating with an insulating mold compound, followed by thinning the central metal plate to isolate the mesas and reduce package size, allowing for multiple dies in a compact integrated package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a lead frame is used to accommodate multiple die pads, then multiple semiconductor dies can be integrated in a single package, but the lead frame lacks sufficient mechanical stability to support the dies
Solution Approach 1:
The central metal plate is segmented into multiple elevated mesas that are electrically isolated from each other. Each mesa serves as an independent die pad, allowing multiple semiconductor dies to be mounted on the same physical substrate while maintaining electrical isolation and mechanical stability.
Solution Approach 2:
The lead frame structure transitions from a two-dimensional planar configuration to a three-dimensional structure with elevated mesas. This vertical dimensionality change provides mechanical support and electrical isolation simultaneously, resolving the contradiction between supporting multiple dies and maintaining stability.
2Adaptability or versatility
If multiple isolated die pads are provided in a single package, then multiple power device dies and logic dies can be integrated, but the package footprint increases due to spacing requirements for creepage and clearance
Solution Approach 1:
By elevating multiple die pads into the vertical dimension as mesas on the central metal plate, the design achieves electrical isolation and creepage/clearance compliance without proportionally increasing the horizontal package footprint. The vertical separation allows compact horizontal arrangement.
Solution Approach 2:
The central metal plate serves multiple functions simultaneously: it provides mechanical support for multiple dies, establishes electrical isolation between dies through mesa structures, and maintains creepage and clearance requirements. This multi-functionality reduces the need for separate structures that would increase package size.
3Adaptability or versatility
If multiple isolated die pads are provided in a single package, then multiple semiconductor dies can be integrated, but the number of electrical connections required increases making the design difficult or impossible within a small footprint
Solution Approach 1:
Multiple electrically isolated die pads are merged onto a single central metal plate structure. This consolidation reduces the number of separate components and interconnections required, simplifying the overall electrical connection architecture while maintaining the ability to integrate multiple different device types.
Data Source
AI summary
A method includes providing a lead frame with a central metal plate and a plurality of leads extending away from the central metal plate, the central metal plate including an upper surface that includes a first mesa that is elevated from recessed regions, mounting a semiconductor die on the upper surface of central metal plate such that a lower surface of the semiconductor die is at least partially disposed on the first mesa, forming electrical interconnections between terminals of the semiconductor die and the leads, forming an encapsulant body on the central metal plate such that the semiconductor die is encapsulated by the encapsulant body and such that the leads protrude out from edge sides of the encapsulant body, and thinning the central metal plate from a rear surface of the central metal plate so as to isolate the first mesa at a lower surface of the encapsulant body.