Stacked Semiconductor Package Leadframe Interconnection
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Solution Overview
Problem
Existing semiconductor package technologies face challenges in achieving low inductance electrical connections between components, which is crucial for high-frequency applications like LIDAR systems and power modules, as they require efficient signal and power transmission without significant parasitic inductance.
Innovation Solution
A semiconductor package design featuring a leadframe with protruding leads and die pads, where a laser module or power transistor die is stacked with a driver die, both in direct electrical communication through the leadframe, minimizing inductance by eliminating additional connectors and using a mold compound that exposes specific surfaces for component attachment and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional semiconductor package structures are used with multiple connectors and indirect connections, then device complexity is reduced and ease of manufacture is improved, but inductance increases and high-frequency performance deteriorates
Solution Approach 1:
The patent merges the driver die and laser module into a stacked configuration where they are directly connected through the leadframe, eliminating the need for separate connectors and wire bonds. This consolidation reduces the number of interconnection points and minimizes parasitic inductance, enabling high-frequency operation while simplifying the overall connection structure.
Solution Approach 2:
The patent transitions from a planar arrangement to a three-dimensional stacked configuration, placing the driver die and laser module on opposite sides of the leadframe. This vertical stacking reduces the current loop area and minimizes inductance by shortening the electrical path length between components, thereby improving high-frequency performance without increasing complexity.
2Productivity
If additional connectors and interconnects are used for component attachment, then ease of manufacture is improved and adaptability is enhanced, but inductance increases and switching frequency capability deteriorates
Solution Approach 1:
The patent extracts and eliminates unnecessary intermediate connectors and interconnects from the traditional package structure. By using the leadframe itself as the direct electrical pathway between the driver die and laser module, the design removes redundant connection elements that contribute to inductance, thereby enhancing switching frequency capability while reducing the quantity of interconnect materials.
Solution Approach 2:
The leadframe serves multiple functions simultaneously: it acts as the structural support, the electrical interconnect, and the mounting substrate for both the driver die and laser module. This multi-functionality eliminates the need for separate connector components, reducing inductance and improving productivity by enabling direct electrical communication between components.
3Ease of manufacture
If mold compound covers all surfaces for protection, then reliability is improved and protection is enhanced, but accessibility for component attachment is reduced and manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by selectively exposing specific surfaces of the leadframe where component attachment is required, while covering other areas with mold compound for protection. This localized approach ensures that the die pads and mounting surfaces remain accessible for attaching the driver die and laser module, while still providing environmental protection where needed, thereby balancing manufacturability with reliability.
Solution Approach 2:
The mold compound application is segmented into different regions: covered areas for environmental protection and exposed areas for component attachment. This segmentation allows the package to simultaneously achieve protection from harmful factors and ease of manufacture by maintaining accessible attachment surfaces without requiring complete surface coverage.
Data Source
AI summary
An embodiment of a semiconductor package includes a leadframe having leads, a mold compound partly encasing the leadframe so that the leads protrude from the mold compound, a power transistor die attached to the leadframe at a first side of the leadframe, and a driver die attached to the leadframe at a second side of the leadframe opposite the first side so that the power transistor die and the driver die are disposed in a stacked arrangement. The driver die is configured to control the power transistor die. The driver die is in direct electrical communication with the power transistor die only through the leadframe and any interconnects which attach the power transistor die and the driver die to the leadframe. Corresponding methods of manufacturing the semiconductor package are also described.