Laser Joining of Metallic Components to Sensitive Substrates
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Solution Overview
Problem
Existing methods for joining thicker metallic components to sensitive components with thin metallization layers often cause damage due to high temperature gradients and stress, particularly in substrates like semiconductors and ceramics, which can crack or degrade.
Innovation Solution
A laser-based method where a first component is thermally separated from a second component, with a laser beam melting the first component to create a melt lens that is deflected by a pressure pulse to bridge the gap and join with the second component, minimizing energy input to the sensitive component and controlling heat penetration to avoid damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional laser beam welding or laser spike welding is used to join thicker metallic components to sensitive components, then the joining strength is improved, but the sensitive component (substrate with thin metallization) is damaged due to high temperature gradients and stress
Solution Approach 1:
The joining process is divided into two distinct phases: a preheating phase that melts the upper component without excessive energy input, and a subsequent phase where additional energy is supplied to generate vapor pressure for material deflection. This segmentation allows controlled heat input that prevents substrate damage while achieving adequate joining strength
Solution Approach 2:
The laser power is dynamically adjusted during the welding process. In the preheating phase, power is kept below the deep welding threshold. During the deflection phase, power is temporarily increased to exceed the boiling temperature and generate vapor pressure. This parameter change enables the process to achieve material deflection without maintaining high temperature that would damage the sensitive substrate
2Length of moving object
If deep welding is used to join thicker components, then the penetration depth is improved, but the energy input to the sensitive component increases causing damage
Solution Approach 1:
The process uses a temporary power increase to rapidly generate vapor pressure and deflect material before excessive heat can conduct into the sensitive substrate. The high energy input is applied briefly during the deflection phase rather than continuously, allowing deep penetration without sustained high energy input that would damage the component
3Adaptability or versatility
If laser spike welding is used to bridge gaps between components, then the gap tolerance is improved, but the temperature increase causes material evaporation and potential damage to the sensitive component
Solution Approach 1:
The welding process uses periodic action with distinct phases: a preheating phase that melts material without excessive temperature increase, followed by a spike phase with temporary power increase to generate vapor pressure for material deflection. This periodic approach enables gap bridging while controlling overall temperature exposure to prevent substrate damage
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
Enables joining of thicker metallic components to sensitive components without damaging the lower component, reducing energy requirements and ensuring a stable, controlled joining process that maintains the integrity of the sensitive substrate.
Implementation Method 1
The at least one laser beam 7 melts the first component 1 locally
Implementation Method 2
the energy QL,a introduced and absorbed via the at least one laser beam 7 in the first component 1 melts the first component 1 locally
Implementation Method 3
The increase in temperature until evaporation is carried out by increasing the power within a laser pulse
Implementation Method 4
The recoil of the steam particles accelerated out of the melt generates a pressure on the melt bath surface
Implementation Method 5
both joining partners are locally melted by the laser beam by heating the first joining partner by the laser beam and locally melting it such that the second joining partner is melted simultaneously by thermal conduction
Data Source
AI summary
A method is disclosed for joining two components (1, 2), a first component (I) and a second component (2), in the region of a joint zone by means of at least one laser beam. In a first phase, the first component (I) is melted, and a melt lens is formed in the first component (I) from the molten material (9). In a second phase, at least one pressure pulse is applied to the melt in the direction of the second component (2) until the melt lens is deflected into the joint gap as a result of the pressure pulse, bridges the joint gap, and comes into contact with the second component (2), and energy is transmitted to the second component (2) as a result of the melt lens coming into contact with the second component. A temperature curve results in the second component (2) as a result of the energy transmission such that the melting temperature is reached on the upper face of the second component (2), and a melt film is formed. The heat penetration depth is set such that a damaging temperature which damages the second component (2) is not exceeded at a specified depth. A method for generating a continuous joint seam is also disclosed.