Metal Foil Pressing Layer for Uniform Insulation Substrate Bonding
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Solution Overview
Problem
Existing methods for manufacturing power module substrates with a two-layer structure face issues such as non-uniform pressurization leading to surface irregularities, bonding failures, and adherence of foreign substances due to the use of carbon layers in spacers, which hinder the mounting of semiconductor elements.
Innovation Solution
A manufacturing method involving the use of metal foils with specific Young's modulus and thickness values to uniformly pressurize and heat laminates of different metal plates, preventing adherence of carbon or ceramic sheets to the surface and ensuring high-quality bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a carbon layer is used in the spacer for pressurizing the laminate, then the displacement due to load application is small, but minute irregularities are generated on the surface of the laminate and bonding failure may occur due to non-uniform pressurization
Solution Approach 1:
A metal foil with specific mechanical properties (Young's modulus of 30-100 GPa and thickness of 0.01-0.1 mm) is introduced as an intermediary layer between the carbon layer and the laminate. This metal foil acts as a mediator that distributes the pressurization force uniformly across the laminate surface while being constrained by the carbon layer, thereby preventing surface irregularities and bonding failures.
2Strength
If the carbon layer forms the surface in contact with the laminate in the spacer, then the spacer provides structural support, but the carbon layer is locally removed by shattering when heated and pressurized, and foreign substances adhere to the laminate surface
Solution Approach 1:
The spacer is segmented into distinct functional layers: a carbon layer for providing structural support and heat resistance, and a separate metal foil layer for direct contact with the laminate. This segmentation allows each layer to perform its specific function without interfering with the other, preventing carbon shattering and foreign substance adherence.
Solution Approach 2:
The metal foil serves as an intermediary protective layer between the carbon layer and the laminate. During heating and pressurization, the metal foil prevents direct contact between the carbon layer and laminate, thereby preventing carbon shattering and foreign substance adherence to the laminate surface.
3Object-generated harmful factors
If strong etching treatment is carried out to remove foreign substances from the laminate surface, then foreign substances are removed, but the surface becomes rough and semiconductor elements cannot be mounted
Solution Approach 1:
Instead of removing foreign substances after they adhere to the laminate, the invention prevents their adherence in the first place by using a metal foil as a protective intermediary layer during the bonding process. This preliminary preventive action eliminates the need for subsequent etching treatment, thereby maintaining surface smoothness for semiconductor element mounting.
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 method enables the production of high-quality bonded bodies with uniform surface bonding and reduced foreign substance adherence, facilitating the mounting of semiconductor elements.
Implementation Method 1
the first metal foil is made of a material which does not react at a contact surface between the first plate member and the first metal foil when heating
Implementation Method 2
solid-phase diffusion bonding may be carried out by pressurizing and heating without interposing the brazing material
Implementation Method 3
it is required to pressurize more uniformly than the bonding interposing the brazing material
Data Source
AI summary
When a laminate of a plurality of different materials including a metal plate is bonded in a pressurized and heated state, a first pressurizing member in which a first metal foil/a carbon sheet or a ceramic sheet/a graphite sheet are laminated in this order is arranged so that the first metal foil is in contact with a surface of the first metal plate of the laminate, the first metal foil is made of a material that does not react at a contact surface of the first plate member and the first metal foil when heating, and a product of a Young's modulus (GPa) and a thickness (mm) of the first metal foil is 0.6 or more and 100 or less, so that a good bonded body can be manufactured by evenly pressurizing the laminate and foreign substances can be restrained from adhering to the surface of the laminate.