Pre-Structured Metallic Circuit Foil for Pore-Free Ceramic Bonding
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Solution Overview
Problem
Current methods for producing electrical circuits on ceramic substrates, such as DCB and AMB, face challenges including the need for aggressive chemicals for etching and the risk of partial discharges due to pores in the connecting layers, which complicates the process and increases costs.
Innovation Solution
A one-piece, flat metallic structure with integrated conductor tracks and connecting webs is used, which can be easily attached to a ceramic substrate using the AMB process, eliminating the need for aggressive chemicals and ensuring a dense, pore-free connection that simplifies the production of electrical circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DCB or AMB techniques are used to bond copper sheets to ceramic substrates, then electrical and thermal connection is improved, but the process requires aggressive chemicals for etching and creates pores in connecting layers
Solution Approach 1:
The copper sheet is pre-structured with conductor tracks and connecting webs in the desired geometry before bonding to the ceramic substrate. This preliminary structuring eliminates the need for post-bonding etching processes that require aggressive chemicals, while the pre-formed design ensures proper electrical connections without creating pores in the connecting layers.
Solution Approach 2:
The harmful etching step using aggressive chemicals is completely removed from the manufacturing process. Instead of bonding a full copper sheet and then etching away unwanted areas, the copper sheet is precisely structured beforehand, extracting the problematic chemical etching step from the process flow.
2Shape
If copper sheets are etched to create conductor tracks, then circuit geometry is achieved, but the process becomes complex and costly
Solution Approach 1:
The copper sheet is pre-cut or pre-structured into the final conductor track geometry and connecting web design before bonding. This preliminary formation of the desired shape eliminates complex multi-step etching processes, reducing manufacturing complexity and cost while achieving the required circuit geometry.
Solution Approach 2:
The copper sheet is divided into functional segments: conductor tracks for electrical connection and connecting webs for mechanical stability. This segmentation allows the structure to achieve complex geometries through simple pre-cutting rather than complex etching processes.
3Ease of operation
If connecting webs are made thin for stability, then handling is improved, but the structure becomes more fragile
Solution Approach 1:
The connecting webs have varying thicknesses optimized for their specific functions: thinner sections where flexibility and handling are needed, and thicker sections where structural strength is critical. This local optimization of material distribution achieves both ease of handling and structural integrity.
Solution Approach 2:
The connecting webs are designed as composite structures combining copper conductor material with the ceramic substrate, creating a hybrid structure that leverages the strength of both materials. The copper-ceramic composite provides both mechanical stability for handling and electrical conductivity for circuit function.
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 approach allows for efficient, cost-effective production of electrical circuits with enhanced partial discharge resistance and improved thermal connection, enabling the creation of complex geometries with reduced operational complexity.
Implementation Method 1
Active metal brazing (AMB) is used to join metallized ceramic components to metal brazing alloys and metal parts. An active element is added to the brazing alloy, or the joining partner is itself an active element alloy. Active elements include titanium or indium, which react with the oxygen in the ceramic during brazing.
Implementation Method 2
Active elements include titanium or indium, which react with the oxygen in the ceramic during brazing.
Implementation Method 3
The metallization also serves to spread heat between the heat sources, i.e., the components (e.g., semiconductors) on the circuit, thereby reducing thermal resistance.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention describes a one-piece, planar metallic structure (3) and a method for fabricating an electrical circuit on a substrate (2) using this structure (3). According to the invention, a one-piece, planar metallic structure (3) is fabricated, which, as a precursor for electrical circuits, consists of conductive traces (5) and/or conductive areas, hereinafter referred to as metallization areas (5). Connecting webs (6) are arranged at suitable locations between the metallization areas (5) for stabilizing and facilitating the handling of the structure (3). The inventive method for fabricating an electrical circuit on a substrate (2) is characterized in that the one-piece, planar metallic structure (3) is attached to the substrate (2) exclusively by means of its metallization areas (5), and the connecting webs (6) of the structure (3) are subsequently removed.