Ultrashort Pulse Laser Processing Composite Materials
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Solution Overview
Problem
Conventional mechanical dicing methods for composite materials, such as those used in printed circuit boards, face challenges like chipping, fraying, and delamination, especially with thin substrates, and involve high environmental costs and thermal or mechanical weakening of materials.
Innovation Solution
Laser-based processing using ultrashort pulses with controlled pulse widths and high repetition rates to minimize heat accumulation and reduce the heat-affected zone, allowing for precise material removal with reduced charring and thermal effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mechanical dicing methods are used for composite materials, then material removal is achieved, but chipping, fraying, and delamination occur especially with thin substrates
Solution Approach 1:
The patent replaces conventional mechanical dicing systems with a laser-based processing system. The laser beam delivers energy to the composite material through optical focusing, eliminating direct mechanical contact that causes chipping, fraying, and delamination. The laser parameters (pulse duration, repetition rate, focal spot size) are controlled to achieve precise material removal without mechanical stress.
Solution Approach 2:
The patent utilizes ultrashort pulse widths (picosecond to femtosecond range) and high repetition rates as key parameters to control the material processing mechanism. These parameter changes enable ablation through nonlinear optical absorption rather than thermal heating, allowing precise cutting of thin composite substrates without the harmful mechanical effects of conventional dicing.
2Productivity
If conventional laser processing with longer pulse widths is used, then material removal is achieved, but heat accumulation and thermal damage increase
Solution Approach 1:
The patent employs periodic pulsed laser action with ultrashort pulse widths and high repetition rates. The pulsed delivery allows each pulse to interact with the material before heat can accumulate significantly, while the high repetition rate maintains productivity. The short pulse duration ensures that thermal diffusion is minimized between pulses, reducing heat-affected zones and thermal damage.
Solution Approach 2:
The patent utilizes nonlinear optical absorption leading to rapid phase transitions (ablation) of the composite material. The ultrashort pulses create extremely high peak powers that induce nonlinear absorption and direct ablation of material without significant thermal heating, eliminating the heat accumulation problem associated with conventional continuous or long-pulse laser processing.
3Productivity
If high repetition rate pulsed lasers are used, then throughput is improved, but heat accumulation may increase if pulse width is not controlled
Solution Approach 1:
The patent combines high repetition rate periodic pulsing with ultrashort pulse widths to achieve high throughput while preventing heat accumulation. The periodic action at high repetition rates delivers many pulses per second for fast processing, while the ultrashort duration of each pulse (picosecond to femtosecond) ensures that the interval between pulses is sufficient to prevent significant thermal diffusion and heat buildup in the material.
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
The method enables efficient and high-quality cutting of composite materials with reduced thermal damage, improved throughput, and minimized environmental impact, suitable for thin substrates and complex shapes.
Implementation Method 1
The focused beam provides a peak power density above a threshold for nonlinear absorption in the composite material
Implementation Method 2
focusing the laser pulses into laser spots having spot sizes (1/e2) in a range from a few microns to about 100 μm
Implementation Method 3
at least one focused laser pulse provides a power density above a threshold for nonlinear absorption in the composite material
Data Source
AI summary
Various embodiments may be used for laser-based modification of target material of a workpiece while advantageously achieving improvements in processing throughput and/or quality. Embodiments of a method of processing may include focusing and directing laser pulses to a region of the workpiece at a pulse width sufficiently short so that material is efficiently removed by nonlinear optical absorption from the region and a quantity of heat affected zone and thermal stress on the material within the region, proximate to the region, or both is reduced relative to a quantity obtainable using a laser with longer pulses. In at least one embodiment, an ultrashort pulse laser system may include at least one of a fiber amplifier or fiber laser. Various embodiments are suitable for at least one of dicing, cutting, scribing, and forming features on or within a composite material.