Metal-Ceramic Substrate Aluminum Metallization Corrosion
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Solution Overview
Problem
Metal-ceramic substrates used in cooling applications, especially in the motor vehicle sector, face challenges in corrosion resistance and thermal conductivity when exposed to fluid or gaseous cooling media, necessitating improved designs for effective cooling without adverse effects.
Innovation Solution
A metal-ceramic substrate with a second metallization layer made of aluminum or aluminum alloy, which can be directly or indirectly connected to the ceramic layer, featuring recesses and cooling elements for enhanced surface area and thermal transfer, and optionally connected via a copper alloy layer for increased durability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a metal-ceramic substrate uses a second metallization layer made of aluminum or aluminum alloy for cooling applications, then thermal conductivity and cooling efficiency are improved, but corrosion resistance deteriorates when exposed to fluid or gaseous cooling media
Solution Approach 1:
A third metallization layer made of corrosion-resistant material (such as stainless steel, nickel, or cobalt) is introduced as an intermediary between the aluminum second metallization layer and the cooling medium. This third layer serves as a protective barrier that prevents direct contact between the aluminum and corrosive cooling media, thereby maintaining both the thermal conductivity benefits of aluminum and the corrosion resistance required for reliable operation in cooling applications
2Ease of operation
If the second metallization layer is made of aluminum or aluminum alloy, then direct contact with cooling media is enabled without long-term impairment, but dissolution in aqueous coolants occurs
Solution Approach 1:
The third metallization layer made of corrosion-resistant material acts as a protective intermediary that prevents aluminum dissolution in aqueous cooling media. This layer allows the aluminum second metallization to maintain its thermal management function while being protected from chemical attack by the coolant, thus enabling long-term operation without material loss
3Strength
If the second metallization is directly connected to the ceramic layer, then structural integrity is improved, but corrosion protection is reduced
Solution Approach 1:
The metallization structure is segmented into three distinct layers: a first metallization layer (copper or copper alloy) directly bonded to the ceramic for structural integrity, a second metallization layer (aluminum or aluminum alloy) for thermal management, and a third metallization layer (corrosion-resistant material) for protection. This segmentation allows each layer to perform its specific function optimally while being bonded together as an integrated structure
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 substrate effectively transfers heat to fluid or gaseous cooling media without corrosion, enabling efficient cooling within existing coolant circuits and maintaining the substrate's functionality, while the anodized aluminum layer prevents dissolution in aqueous coolants.
Implementation Method 1
the second metallization is brought into direct contact with fluid or gaseous cooling media for cooling purposes
Implementation Method 2
the metal-ceramic substrate is subject to specific requirements, for example, with regard to corrosion resistance and thermal conductivity. When using such substrates in the automotive sector, it is desirable, for instance, to use the coolant circuit intended for cooling the vehicle also for cooling the substrate
Implementation Method 3
the anodized aluminum layer prevents dissolution in aqueous coolants
Data Source
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AI summary
The invention relates to a metal-ceramic substrate and to a method for the production thereof, comprising at least one ceramic layer (2), which is provided on a first surface side (2a) with at least one first metallization (3) and on a second surface side (2b), opposite from the first surface side (2a), with a second metallization (4), wherein the first metallization (3) is formed by a film or layer of copper or a copper alloy and is connected to the first surface side (2a) of the ceramic layer (2) with the aid of a "direct copper bonding" process. Particularly advantageously, the second metallization (4) is formed by a layer of aluminium or an aluminium alloy.