Thermal Management Package for Semiconductor Devices
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Solution Overview
Problem
Current semiconductor mounting structures face challenges in thermal management, size reduction, weight minimization, and cost effectiveness for high-power RF semiconductor devices, particularly due to the limitations of high dielectric constant materials which are soft and difficult to work with, leading to increased costs and complexity.
Innovation Solution
Embedding a high thermal conductivity slug within a high dielectric constant material substrate and placing it within a window in a low dielectric constant outer substrate, allowing for a compact geometry, improved manufacturability, and reduced weight, while using materials like Cu, AlN, or diamond for enhanced thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high dielectric constant material substrate is used to reduce RF matching circuitry size, then the electrical performance is improved, but the material becomes soft and difficult to work with, increasing manufacturing complexity and cost
Solution Approach 1:
The substrate is divided into two distinct regions: a first substrate region made of high dielectric constant material for RF matching circuitry, and a second substrate region made of low dielectric constant material for power delivery. This segmentation allows each region to be optimized for its specific function while avoiding the manufacturing difficulties of using high dielectric constant material throughout the entire substrate.
Solution Approach 2:
Different dielectric constant materials are applied locally to different regions of the substrate based on functional requirements. The high dielectric constant material is used only where RF matching is needed, while the low dielectric constant material is used where power delivery and manufacturing ease are priorities. This local quality approach resolves the contradiction by providing high electrical performance only where necessary.
2Temperature
If a copper slug insert is used for thermal management, then thermal conductivity is improved, but the fabrication cost increases from $0.01/mm2 to $0.06/mm2
Solution Approach 1:
The thermal management function is merged with the existing via structure by filling the via with copper material. This eliminates the need for a separate copper slug insert while achieving the same thermal conductivity improvement. The via-in-pad structure combines the electrical connection function with the thermal management function, reducing overall fabrication cost.
Solution Approach 2:
The via structure is given multiple functions: it serves as both an electrical connection path and a thermal management path. By making the via multi-functional, the patent eliminates the need for separate dedicated thermal management components like copper slugs, thereby reducing fabrication cost while maintaining thermal performance.
3Area of stationary object
If the substrate size is reduced for compact packaging, then the device size is reduced, but thermal management capability is compromised
Solution Approach 1:
The substrate uses a composite structure with regions of different dielectric constant materials, and the via structures use composite material approaches by filling with copper. This allows efficient thermal management within a compact area by concentrating thermal pathways at critical locations rather than requiring a large substrate area for distributed thermal management.
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 approach results in a more robust, cost-effective, and smaller thermal management package that can handle higher RF power and current, with reduced size and weight, and eliminates cracking issues, improving both electrical performance and manufacturing yields.
Implementation Method 1
a high thermal conductivity slug disposed in a first window in a high dielectric constant material substrate
Data Source
AI summary
A thermal management package for a semiconductor device includes a high dielectric constant material substrate, a high thermal conductivity slug disposed in a first window in the high dielectric constant material substrate and held therein by a first bonding material, an outer substrate formed from a material having a low dielectric constant and having a second window formed therein, the high dielectric constant material substrate disposed in the second window in the low dielectric constant outer substrate and held therein by a second bonding material.