Double-sided cooling package for double-sided, bi-directional junction transistor
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Solution Overview
Problem
Traditional cooling packages are inadequate for double-sided, bi-directional junction transistors, failing to effectively manage heat and electrical current due to asymmetrical soldering and structural limitations, which hampers the performance and reliability of these advanced power devices.
Innovation Solution
A double-sided cooling package design featuring direct plating copper (DPC), direct copper bonding (DCB), and direct aluminum bond (DAB) structures with symmetrical copper or aluminum layers and sintering silver (Ag) soldering to ensure efficient heat dissipation and electrical conductivity across both sides of the transistor assembly, allowing for high-power operation with reduced thermal and electrical impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional cooling packages are used for double-sided transistors, then the package structure is simple and easy to manufacture, but heat dissipation efficiency deteriorates and thermal resistance increases
Solution Approach 1:
The cooling package is segmented into two independent heat sinks, each attached to one side of the transistor chip. This allows each heat sink to independently manage heat dissipation from its respective side, improving overall thermal efficiency without requiring a completely new monolithic structure
Solution Approach 2:
The invention transitions from single-sided to double-sided cooling by adding thermal management capability in the vertical dimension. Heat sinks are attached to both the front and back sides of the transistor chip, utilizing both surfaces for heat dissipation and effectively doubling the cooling capacity
2Reliability
If asymmetrical soldering is used in traditional packages, then manufacturing process is simple, but electrical conductivity and reliability deteriorate
Solution Approach 1:
The invention deliberately employs asymmetrical soldering configurations where different soldering patterns, materials, or processes are applied to different sides of the transistor chip. This allows optimization of electrical conductivity and thermal management for each side's specific requirements, improving overall device performance and reliability
Solution Approach 2:
Different soldering characteristics are applied to different regions of the package. For example, one side may use reflow soldering while the other uses wave soldering, or different solder alloy compositions are used on each side to optimize for local electrical and thermal requirements
3Temperature
If traditional single-sided cooling packages are used, then manufacturing is easier, but thermal resistance increases and cooling efficiency deteriorates
Solution Approach 1:
The cooling system is divided into two separate heat sink assemblies, each independently mounted to one side of the transistor chip. This segmentation allows each heat sink to be optimized for its specific side's thermal characteristics and enables parallel heat dissipation pathways
Solution Approach 2:
The cooling architecture extends from single-sided to double-sided by utilizing both surfaces of the transistor chip for heat dissipation. This dimensional expansion effectively doubles the available cooling surface area and creates independent thermal management zones
4Temperature
If double-sided cooling structure is implemented, then heat dissipation improves and thermal resistance decreases, but manufacturing precision requirements increase
Solution Approach 1:
Heat sinks are pre-attached to the transistor chip sides in controlled manufacturing steps before final assembly. This preliminary action allows for precise alignment and bonding under controlled conditions, ensuring optimal thermal contact without requiring ultra-precise alignment during final package assembly
Solution Approach 2:
Thermal interface materials or intermediary bonding layers are used between the heat sinks and transistor chip surfaces. These intermediaries compensate for minor misalignments and surface irregularities, maintaining effective thermal contact while reducing the stringency of alignment precision requirements
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 proposed cooling package enhances the performance and reliability of double-sided transistors by enabling efficient double-sided cooling, symmetrical soldering, and high electrical current handling, overcoming the limitations of traditional packages and achieving reduced thermal resistance and impedance.
Implementation Method 1
sintering the sintering Ag to convert the sintering Ag to pure Ag
Implementation Method 2
Each heat sink can include a direct plating copper (DPC) structure, a direct copper bonding (DCB) structure or a direct aluminum bond (DAB) structure
Data Source
AI summary
A double-sided cooling package for a double-sided, bi-directional junction transistor can include a double-sided, bi-directional, junction transistor chip with an individual, double-sided, bi-directional power switch (collectively, a DSTA). The DSTA can be sandwiched between heat sinks. Each heat sink can include a direct plating copper (DPC) structure, a direct copper bonding (DCB) structure or a direct aluminum bond (DAB) structure. In addition, each heat sink can have opposed first and second copper layers on a substrate, and copper contacts that extend from a respective second copper layer through vias in each substrate to an exterior of the cooling package.