Embedded Power Die PCB With Nano-Wire Interconnect Thermal Relief
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Solution Overview
Problem
The reliability of interconnections between power dies and copper pads on printed circuit boards is compromised by thermo-mechanical stress, leading to potential failure due to coefficient of thermal expansion mismatches and thermal gradients, and nano-wire interconnections can suffer from adhesion, conglomeration, and oxidation under heat and current.
Innovation Solution
The use of soft micro/nano copper wires with a high length-to-diameter ratio, forming a nano-wire forest, is enhanced by surface coating to prevent adhesion and oxidation, and a dielectric fluid is introduced to reduce thermal resistance, increase thermal capacitance, and prevent conglomeration, while flexible membranes allow for thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nano-wire interconnections are used to improve flexibility and absorb thermal expansion, then reliability under thermo-mechanical stress is improved, but adhesion and conglomeration occur under heat and current
Solution Approach 1:
A dielectric fluid is introduced as an intermediary substance between the nano-wires and the environment. This fluid prevents direct contact between nano-wires, eliminating adhesion and conglomeration while maintaining the flexibility and thermal expansion absorption capabilities of the nano-wire interconnections.
Solution Approach 2:
The dielectric fluid creates an inert environment around the nano-wires, protecting them from oxidation and chemical reactions under heat and current. This inert environment maintains the nano-wire structure stability while preserving their mechanical flexibility and electrical conductivity.
2Strength
If conventional interconnection methods (soldering, sintering, direct copper deposition) are used, then strong electrical connection is achieved, but flexibility to absorb thermal expansion is lost
Solution Approach 1:
The invention changes the physical parameters of the interconnection from rigid (conventional methods) to flexible (nano-wires). By using nano-scale dimensions and introducing a dielectric fluid, the system achieves both strong electrical connection and adaptability to thermal expansion through the flexible nano-wire structure.
3Power
If the density of nano-wires is increased to improve current and heat transfer, then electrical and thermal conductivity is improved, but adhesion and conglomeration risk increases
Solution Approach 1:
The dielectric fluid acts as a spacer and mediator between densely packed nano-wires, preventing adhesion and conglomeration even at high densities. This allows the system to achieve high current and heat transfer capability through increased nano-wire density without sacrificing reliability.
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 solution effectively absorbs mechanical displacements, maintains interconnection flexibility, reduces thermal resistance, prevents nano-wire oxidation and conglomeration, and enhances the robustness of the power module under thermal and electrical stress.
Implementation Method 1
a dielectric fluid is introduced to reduce thermal resistance
Implementation Method 2
increase the thermal capacitance
Implementation Method 3
The mechanical displacements due to thermal effects between the die and the printed circuit board are absorbed by the nano wires
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~5
AI summary
The present invention concerns a printed circuit board embedding a power die wherein interconnections between the power die and the printed circuit board are composed of micro/nano wires, the printed circuit board comprising a cavity wherein the power die is placed, and wherein the cavity is further filled with a dielectric fluid.