PCB Trace And Microvia Patterning With Two-Step Ultrafast Lasers
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Solution Overview
Problem
Current methods for creating printed circuit board (PCB) fine traces and micro vias are limited by the need for toxic chemicals, multiple time-consuming steps, and the inability to produce structures smaller than 50-70 μm due to the inherent hole size limitations of CO2 laser drilling processes.
Innovation Solution
A two-step process using an ultrafast pulsed laser to define patterns on a conductive material layer, followed by longer wavelength laser radiation to create smaller traces and vias without chemical treatment, allowing for the creation of nanostructured ridges and valleys that increase surface area and reduce reflectivity, enabling the production of smaller features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CO2 laser drilling process is used to create vias, then the process is simple and direct, but the hole size is limited to greater than 50-70 μm due to diffraction limitations
Solution Approach 1:
The patent segments the via creation process into two distinct stages: first using an ultrafast UV laser to drill precise micro-holes through the copper layer, then using a CO2 laser to clean and prepare the hole for plating. This segmentation allows each laser type to perform its optimal function - the UV laser creates precise sub-35μm holes while the CO2 laser efficiently cleans and de-smears the copper surfaces.
Solution Approach 2:
The patent introduces an intermediary copper layer that serves as a mask for the CO2 laser. The copper layer is selectively removed by the UV laser to create small aperture openings, which then act as masks that allow the CO2 laser to drill through only at the desired locations. This intermediary approach enables precise positioning while maintaining high productivity.
2Manufacturing precision
If UV laser is used to directly drill copper for micro vias, then smaller via diameters can be achieved, but the equipment cost is high and throughput is compromised
Solution Approach 1:
The patent merges the advantages of two different laser technologies into a single integrated process. The UV laser provides precise hole formation capability while the CO2 laser provides efficient material removal and surface preparation. By combining these two laser types in sequence, the system achieves both the precision needed for sub-35μm vias and the productivity required for manufacturing.
3Ease of manufacture
If Direct Imaging process is used with photoactive laminate, then conductive lines can be created, but toxic chemicals and corrosive etchants are required
Solution Approach 1:
The patent replaces the chemical-based Direct Imaging process with a laser-based ablation process. Instead of using photoactive laminates, developers, and corrosive etchants, the system uses focused laser beams to directly ablate the copper conductive lines and substrate material. This substitution eliminates all toxic chemicals while maintaining the ability to create precise conductive traces and patterns.
Solution Approach 2:
The laser ablation process is self-contained and does not require external chemical agents. The laser energy directly interacts with the material to achieve the desired patterning, eliminating the need for separate chemical treatment steps. The process uses only laser parameters (wavelength, pulse duration, power, scanning speed) to control the ablation outcome.
4Use of energy by moving object
If black oxide layer is applied to copper surface for CO2 laser drilling, then reflectivity is reduced, but additional chemical treatment steps are required
Solution Approach 1:
Instead of pre-treating the copper surface with black oxide to improve CO2 laser absorption, the patent inverts the approach by using the UV laser first to create precise holes through the reflective copper layer. The copper layer then serves as a mask for the subsequent CO2 laser step, eliminating the need for black oxide treatment entirely.
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 method eliminates the need for toxic chemicals and expensive UV lasers, allowing for the creation of finer traces and vias less than 35 μm in diameter with improved manufacturing throughput and reduced costs.
Implementation Method 1
an ultrafast pulsed laser to define patterns on a conductive material layer, followed by longer wavelength laser radiation to create smaller traces and vias without chemical treatment, allowing for the creation of nanostructured ridges and valleys that increase surface area and reduce reflectivity
Implementation Method 2
A first laser pulse removes the top layer of oxide, copper and some substrate material. A second laser pulse from the CO2 laser removes the substrate material down to the next copper layer
Data Source
AI summary
A method for fabricating a printed circuit, comprising: darkening a surface location of a conductive material with one or more ultrafast pulses of laser radiation and ablating the conductive material at the surface location with one or more longer duration pulses of laser radiation to produce traces or micro via patterns on the surface of a PCB. A hole for a blind micro via is produced by ablating the conductive material at the darkened surface location with one or more longer duration pulses of laser radiation and cleaning a second conductive material under the substrate with one or more further longer duration pulses of laser radiation.