Plastic Pre-Molded Cavity Package With Metal Heat Sink
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Solution Overview
Problem
Ceramic cavity packages are expensive, exhibit poor thermal performance, and are not scalable for mass production, while plastic over-molded packages lack a cavity and have a poor thermal path from the leadframe to the heat sink.
Innovation Solution
A metal heat sink is attached to a leadframe via a thermally conductive but electrically insulating intermediate structure, and a plastic body is molded to form a cavity with partially exposed lead surfaces and heat sink surfaces, allowing for improved thermal conductivity and sealing with a lid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic cavity packages are used, then hermetic sealing and cavity protection are achieved, but cost increases and thermal performance deteriorates
Solution Approach 1:
The patent replaces expensive ceramic materials with a plastic encapsulant that provides equivalent hermetic sealing functionality at lower cost. The plastic mold compound serves as a disposable protective enclosure that achieves the same hermetic sealing purpose without the high material and manufacturing costs of ceramic packages.
Solution Approach 2:
The patent changes the material parameter from ceramic to plastic encapsulant, fundamentally altering the package composition while maintaining hermetic sealing capability. This material substitution enables cost reduction while preserving the protective enclosure function through different physical and chemical properties of the plastic material.
2Reliability
If ceramic cavity packages are used, then hermetic sealing is achieved, but thermal performance deteriorates
Solution Approach 1:
The patent divides the package into functionally distinct segments: a plastic encapsulant for hermetic sealing and a separate metal heat sink for thermal management. This segmentation allows each component to optimize its specific function without compromise, with the heat sink providing direct thermal pathways while the plastic provides sealing.
Solution Approach 2:
The patent introduces a metal heat sink as an intermediary component between the semiconductor die and the external environment. This heat sink acts as a thermal mediator that conducts heat away from the die efficiently while being integrated into the plastic encapsulated package, thus improving thermal performance without compromising hermetic sealing.
3Ease of manufacture
If plastic over-molded packages are used, then manufacturing cost decreases, but thermal path performance deteriorates
Solution Approach 1:
The patent merges the plastic encapsulant and metal heat sink into a single integrated package structure where both components work together. The heat sink is embedded within or attached to the plastic mold compound, creating a unified thermal management system that maintains low cost while significantly improving the thermal path from die to heat dissipation interface.
4Manufacturing precision
If ceramic cavity packages are used, then individual assembly precision is achieved, but productivity decreases
Solution Approach 1:
The patent creates a universal plastic mold compound encapsulation process that can accommodate multiple different semiconductor devices and configurations within the same manufacturing framework. This universal approach allows standardized mass production techniques to be applied across various device types, significantly improving productivity while maintaining adequate precision through the mold compound's inherent forming capabilities.
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
The solution results in a cost-effective, high thermal and electrical performance package suitable for high power and high frequency applications, with enhanced scalability and reduced manual handling.
Implementation Method 1
a thermally conductive but electrically insulating intermediate structure
Implementation Method 2
a thermally conductive but electrically insulating intermediate structure
Implementation Method 3
a metal heat sink is attached to a leadframe via an intermediate structure that is thermally conductive
Implementation Method 4
a plastic body is molded onto the integrated heat sink and leadframe to form a cavity
Data Source
AI summary
A cavity package is set forth along with a method of manufacturing thereof. According to one embodiment, the method comprises attaching a metal heat sink to a leadframe using an intermediate structure that is thermally conductive and electrically insulating; molding a plastic body around the heat sink and exposed leads of the leadframe to form a cavity, with partially and selectively exposed lead top surfaces, heat sink top surface, and heat sink bottom surface; attaching a semiconductor device die within cavity on to the exposed top surface of the heat sink using a thermal conductive material; wire bonding respective wire bond pads of the semiconductor device die to the exposed lead top surfaces and to the heat sink for grounding; and attaching a lid to the plastic molded body to protect the wire bonded device within cavity.