Aluminum Circuit Board with Printed Conductor Paste
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Solution Overview
Problem
In power electronics, achieving direct electrical contact between electronic components and aluminum-based substrates is challenging due to the formation of a protective oxide layer on aluminum, which complicates soldering and other connection methods, and existing printed circuit boards require insulating layers that increase complexity and cost.
Innovation Solution
A printed circuit board design featuring a conductive layer directly connected to the substrate, applied via screen printing, eliminates the need for insulating layers, allowing the substrate to function as both a heat sink and electrical conductor, with a dielectric layer applied to prevent sparks and reduce module size, and a conductor paste is used to create solderable areas on aluminum substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating layer is arranged between the aluminum substrate and the conductor surface, then electrical insulation is provided, but the structure becomes more complex and production costs increase
Solution Approach 1:
The patent removes the insulating layer from the structure by applying a conductor paste directly onto the aluminum substrate. The conductor paste itself provides both electrical conduction and insulation functions through its composition and application method, eliminating the need for a separate insulating layer and simplifying the overall structure.
Solution Approach 2:
The conductor paste serves multiple functions simultaneously: it provides electrical conduction through its conductive particles, creates a solderable surface, and provides electrical insulation from the aluminum substrate. This multi-functionality eliminates the need for separate insulating layers and reduces structural complexity.
2Reliability
If a conductor paste is applied directly to the aluminum substrate, then direct electrical contact is achieved, but the oxide layer on aluminum complicates the connection process
Solution Approach 1:
The conductor paste acts as an intermediary material between the aluminum substrate and the electronic components. It penetrates or bonds through the oxide layer to create reliable electrical contact with the aluminum substrate, while simultaneously providing a solderable surface for mounting components, thus resolving the manufacturing difficulty.
Solution Approach 2:
The conductor paste is a composite material containing conductive particles (such as silver, copper, or aluminum powder), glass frit, and organic binders. This composite structure enables it to bond to the oxidized aluminum surface while maintaining electrical conductivity and providing a solderable surface, overcoming the oxide layer barrier.
3Temperature
If the substrate is used exclusively for heat conduction with conductor tracks on an insulating layer, then thermal management is improved, but electrical current carrying capability is limited
Solution Approach 1:
The aluminum substrate is designed to serve dual functions: thermal conduction and electrical current carrying. By applying conductor paste directly to the substrate and using the substrate itself as a current-carrying element, the design eliminates the limitation of having conductor tracks only on insulating layers, thereby increasing power handling capability while maintaining heat dissipation efficiency.
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 design simplifies the printed circuit board structure, reduces production costs, enables the substrate to handle high electrical currents, and allows for compact power electronics modules with improved electrical and thermal conductivity, while enabling direct soldering of components, thus enhancing reliability and efficiency.
Implementation Method 1
in a first firing phase the conductor paste is sintered to the substrate, in a second firing phase the conductor paste is exposed to a predeterminable maximum firing temperature of less than about 660 °C.
Implementation Method 2
Aluminum has both a very high thermal conductivity and a very high electrical conductivity for these purposes.
Implementation Method 3
Aluminum has both a very high thermal conductivity and a very high electrical conductivity for these purposes.
Implementation Method 4
the formation of a protective oxide layer on aluminum
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The invention relates to a circuit board (1a, 1b, 1c), particularly for a power-electronic module (2), comprising an electrically-conductive substrate (3) which consists, at least partially and preferably entirely, of aluminium and/or an aluminium alloy. On at least one surface (3a, 3b) of the electrically-conductive substrate (3), at least one conductor surface (4a, 4b) is arranged in the form of an electrically-conductive layer applied preferably using a printing method and more preferably using a screen-printing method, said conductor surface (4a, 4b) being in direct electrical contact with the electrically-conductive substrate (3).