Ultrashort Pulse Laser Trimming Metal-Ceramic Substrates
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Solution Overview
Problem
Conventional methods for trimming metal-ceramic substrates, especially those for high voltage applications, are prone to damaging the isolator and inducing cracks during laser trimming, making it difficult to achieve precise resistance values without separate passive components.
Innovation Solution
The method involves using ultrashort pulse laser ablation to trim conductive metal layers on metal-ceramic substrates in a z-axis direction, reducing thickness locally to achieve specific resistivity values, eliminating the need for separate resistors and allowing precise resistance adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional laser trimming is used on metal-ceramic substrates for high voltage applications, then resistance values can be adjusted, but the isolator is damaged and cracks are induced during trimming
Solution Approach 1:
The patent changes the laser process parameters by using ultrashort pulse durations (picosecond to femtosecond range) instead of conventional continuous or long-pulse laser trimming. This parameter change enables precise resistance adjustment while preventing thermal damage to the isolator and substrate, resolving the contradiction between trimming precision and substrate integrity
Solution Approach 2:
The patent employs periodic ultrashort laser pulses for material removal during trimming. This periodic pulsed action allows controlled ablation of the conductive layer to achieve precise resistance values while the short pulse duration prevents heat accumulation that would damage the isolator, simultaneously achieving both precision and reliability
2Reliability
If separate passive components are used to achieve resistance values, then reliable resistance can be achieved, but device complexity increases and separate components are required
Solution Approach 1:
The patent merges the function of separate passive resistance components into the metal-ceramic substrate itself by trimming the conductive layer to create integrated resistors. This integration eliminates separate components, reduces device complexity, and maintains reliability through precise control of the trimming process that prevents isolator damage
Solution Approach 2:
The metal-ceramic substrate is given multiple functions: it serves as both the mechanical support structure and as the resistor element through laser trimming of the conductive layer. This multi-functionality eliminates the need for separate passive components while maintaining the substrate's primary functions, reducing overall device complexity without sacrificing reliability
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 enables precise trimming of metal-ceramic substrates without damaging the isolator, allowing for the elimination of separate resistors and achieving resistance values from 1 mOhm to 1 kOhm, with high material removal rates and thermal stability.
Implementation Method 1
laser ablation with an ultrashort pulse laser is performed locally on at least one conductive metal layer within a certain ablation area
Implementation Method 2
The ablation consists of a series of discrete single laser pulses which remove material from the ablation area
Data Source
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AI summary
The invention relates to a method for manufacturing a metal-ceramic substrate (10), including providing a central ceramic insulation layer (20) with a conductive metal layer (30) on one or both of its surfaces. Laser ablation with an ultrashort pulse laser is performed on at least one conductive metal layer (30) locally within an ablation area (31) until a certain resistivity of the conductive metal layer (30) is achieved in this ablation area (31). Thereby, the thickness of the conductive metal layer (30) in the ablation area (31) is reduced to a value above zero so that certain resistance values can be achieved in order to form resistors on the metal-ceramic substrate (10). The invention also relates to a corresponding metal-ceramic substrate which has been manufactured by such method. In particular, the conductive metal layer (30) is made of copper which is applied to the central ceramic layer (20) by means of a DCB process to form a DCB substrate.