Lead Frame Ceramic Air Cavity Package Thermal Dissipation
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Solution Overview
Problem
Ceramic semiconductor packages face high thermal resistance issues, leading to excessive temperature rise and reliability concerns, while injection molded plastic packages detune high-frequency performance and risk damaging delicate structures during molding.
Innovation Solution
A ceramic semiconductor package with a direct attachment to a lead frame, creating an air cavity for hermetic signal routing and enhanced thermal dissipation by mounting the device directly on the lead frame, which acts as a heat sink, eliminating intermediate layers and providing a conductive path for heat removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic base with vias is used to mount the semiconductor device, then the package provides structural support and electrical connections, but the thermal resistance through the ceramic base is too high to effectively dissipate heat
Solution Approach 1:
The invention extracts the semiconductor device from the conventional ceramic base mounting structure and directly mounts it to the lead frame. This removes the high thermal resistance ceramic base from the heat dissipation path, allowing heat to flow directly through the lead frame to the heat sink, thereby resolving the thermal dissipation problem while maintaining structural support through the air cavity package design.
Solution Approach 2:
The air cavity acts as an intermediary structure that enables direct thermal contact between the device and lead frame while providing electrical insulation and mechanical support. The ceramic frame surrounding the air cavity serves as both a structural element and a thermal management component, facilitating heat dissipation through the lead frame without requiring high thermal conductivity through the ceramic base itself.
2Reliability
If injection molding is used to encapsulate the semiconductor device, then the package provides environmental protection and structural integrity, but the molding process can destroy delicate structures on the device surface
Solution Approach 1:
The invention extracts the semiconductor device from the injection molding process entirely. By mounting the device directly to the lead frame and sealing it within the air cavity package using ceramic and metal components, the delicate device structures are never exposed to the high-pressure molding process, thereby preventing damage while still providing environmental protection through the hermetic seal.
Solution Approach 2:
The air cavity package design replaces the disposable plastic mold compound with a reusable, durable ceramic and metal construction. The package can be assembled through controlled processes that do not damage the device, and the resulting structure provides long-term environmental protection without the need for destructive encapsulation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively addresses thermal dissipation and electromagnetic interference issues, enabling high-power and high-frequency semiconductor devices to operate reliably by providing a low thermal resistance path and maintaining signal integrity.
Implementation Method 1
power dissipation, i.e., heat dissipation, is more effectively provided by this direct connection without intervening layers of ceramic or conductor as in conventional packages
Implementation Method 2
mounting the device directly on the lead frame, which acts as a heat sink
Implementation Method 3
The ceramic package thus provides a hermetic insulated path through which the signals can be routed from the device to the external leads
Data Source
AI summary
A ceramic semiconductor package provides for being surface mounted on a printed circuit board or other mounting surface. A ceramic frame is directly attached to a lead frame to define a cavity in which the base of a semiconductor device is mounted to the portion of the lead frame exposed at the bottom of the cavity. Interface terminals of the semiconductor device are attached to electrical contacts on the ceramic frame inside the cavity. The ceramic package provides a hermetic insulated path through which the signals can be routed from the device to the external leads. Additionally, because the semiconductor device is directly attached to the lead frame, power dissipation, i.e., heat dissipation, is more effectively provided by this direct connection without intervening layers of ceramic or conductor.