Laser Soldering of Substrate Terminal Faces With Two-Phase Heating
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Solution Overview
Problem
Existing methods for electrically contacting terminal faces of two substrates are inefficient in terms of energy consumption and often result in damage to temperature-sensitive substrates due to undesirable burning.
Innovation Solution
A method involving a two-phase laser application process, where a first laser radiation preheats the substrates and solder material, increasing their absorption capacity, and a second laser radiation with a different wavelength is used to efficiently fuse the solder material and establish an electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser radiation is applied directly to fuse solder material, then electrical contact is established, but energy consumption increases and substrate damage occurs due to reflection and burning
Solution Approach 1:
The patent applies a preliminary heating phase before the fusing phase. The substrate is preheated to increase its absorption capacity for laser radiation, reducing reflection losses during the subsequent fusing operation. This preliminary action enables more efficient energy utilization when fusing the solder material.
Solution Approach 2:
The patent divides the laser application into distinct periodic phases: a first heating phase and a second fusing phase. Each phase uses appropriately tuned laser parameters (power, duration, wavelength) optimized for its specific purpose, rather than applying continuous high-power radiation that would cause both energy waste and substrate damage.
2Productivity
If high power laser radiation is used to fuse solder material quickly, then productivity increases, but substrate damage occurs due to burning
Solution Approach 1:
The substrate is preheated in a first phase to the optimal temperature for solder fusing. This preliminary heating eliminates the need for excessive high-power laser radiation during the actual fusing phase, as the substrate is already at the appropriate temperature, thereby preventing burning while maintaining fast processing speed.
Solution Approach 2:
The laser application is divided into two periodic phases with different power levels and durations. The first phase uses moderate power for heating, and the second phase uses optimized power for fusing. This periodic structure enables rapid connection while controlling the total energy input to prevent substrate burning.
3Device complexity
If single-wavelength laser radiation is used for both heating and fusing, then device complexity is reduced, but energy efficiency decreases due to suboptimal absorption
Solution Approach 1:
The patent changes the laser wavelength parameter between two phases: using a first wavelength (e.g., infrared) for heating the substrate to increase absorption capacity, and a second wavelength (e.g., green or blue) for fusing the solder material. This parameter change optimizes absorption at each stage, reducing reflection losses without requiring complex multi-laser systems.
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 reduces energy consumption by minimizing reflection and maximizing absorption, thereby achieving reliable electrical contact with reduced risk of substrate damage.
Implementation Method 1
a first laser radiation is applied to at least one of the substrates, namely the first or the second substrate, on the rear side
Implementation Method 2
The terminal faces of the substrate are arranged on the front side of the substrate opposite the rear side, with a solder material arranged between the terminal faces of the first substrate and the second substrate
Implementation Method 3
a second laser radiation is applied to at least one of the substrates using a second laser device in a second application phase
Implementation Method 4
the solder material arranged between the substrates is fused at least to such an extent that an electrical contact is established between the terminal faces
Data Source
AI summary
A method for electrically contacting terminal faces of two substrates, the first substrate being positioned against the terminal faces of the second substrate, and a first laser radiation being applied to at least one of the substrates on the rear side in a first application phase, and a second laser radiation being applied to at least one of the substrates in a second application phase and a solder material arranged between the substrates being fused to establish an electrical contact between the terminal faces of the substrates, and the application in the first application phase being carried out with a first laser radiation, which has a wavelength that differs from the second laser radiation, and the switch from the first application phase to the second application phase being controlled by a control device A laser arrangement for applying laser energy to at least one substrate is proposed.