PCB Cooling Cavity Integration for Embedded Power Semiconductor Heat Removal
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Solution Overview
Problem
The increasing power density and switching frequency in power electronics, particularly with Wide Band Gap semiconductors, lead to enhanced heat flux density, which is hindered by the limited heat transfer capabilities of copper micro vias in embedded die power packaging, necessitating improved thermal management.
Innovation Solution
An integrated cooling liquid cavity is created in a printed circuit board by inserting a power semiconductor die into a dielectric material, laminating with conducting layers, drilling and metallizing vias, and using a soluble material to form a cavity that is later filled with cooling liquid, reducing the thermal path between the die and coolant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If copper micro vias are used for heat transfer in embedded die packaging, then electrical connectivity is achieved, but heat transfer capability is limited
Solution Approach 1:
The thermal management structure is segmented into multiple functional zones: copper vias for electrical connectivity, dielectric material layers for insulation and structural support, and a dedicated cooling liquid cavity for primary heat removal. This segmentation allows each component to optimize its specific function rather than relying on copper vias for both electrical and thermal purposes.
Solution Approach 2:
A cooling liquid cavity is introduced as an intermediary medium between the power semiconductor die and the external cooling system. The cooling liquid directly contacts the die through the dielectric material, providing a high-efficiency thermal conduction path that bypasses the limited heat transfer capability of copper micro vias.
2Power
If power density is increased in power electronics, then converter performance is improved, but heat flux density increases beyond the capacity of copper vias
Solution Approach 1:
The invention employs a liquid cooling system where cooling liquid is pumped through a cavity in direct thermal contact with the power semiconductor die. This hydraulic cooling approach provides superior heat extraction capability compared to solid conduction through copper vias, enabling the system to handle the high heat flux density generated by increased power density without thermal runaway.
3Loss of energy
If a cooling liquid cavity is integrated into the PCB, then heat transfer is enhanced, but manufacturing complexity increases
Solution Approach 1:
The cooling liquid cavity is formed during the PCB lamination process by placing a soluble material (such as sugar or salt) in the desired cavity shape between dielectric material layers. The soluble material acts as a temporary placeholder that maintains the cavity volume during manufacturing. After lamination, the soluble material is dissolved by injecting solvent, leaving the final cooling cavity. This preliminary action allows the cavity to be integrated without requiring post-fabrication machining or complex molding operations.
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 significantly enhances heat transfer by placing the coolant in direct contact with the conducting layers, effectively addressing the limitations of copper vias in high-power embedded die packaging and improving thermal management.
Implementation Method 1
injecting solvent in the soluble material in order to dissolve the soluble material and reveal a cavity
Implementation Method 2
the coolant is in direct contact with the closest electrically conducting layer reducing drastically the thermal path between the die and the coolant
Data Source
AI summary
The present invention concerns a method and a device for making an integrated cooling liquid cavity in a printed circuit board by inserting a power semiconductor die in a dielectric material, laminating the dielectric material with a dielectric material and a thin electrically conducting layer on each side of the dielectric material, drilling vias through the laminated copper and dielectric layers, metallizing the vias in order to form a first printed circuit board, laminating a dielectric material, a soluble material having a predetermined form and an electrically conducting layer on the first printed circuit board, injecting solvent in the soluble material in order to dissolve the soluble material and reveal a cavity injecting cooling liquid in the revealed cavity.