Laser Machining Apparatus for PCB Hole Drilling
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Solution Overview
Problem
Conventional laser machining methods face challenges in machining copper layers and insulating layers on printed circuit boards, particularly with delamination, overhang, and hole shape issues, while maintaining machining efficiency and accuracy.
Innovation Solution
A laser machining method using a first and second pulsed laser beam with controlled irradiation positions and energy densities, along with a beam splitter and acousto-optical elements to time-share the laser beams, reducing heat input and improving machining quality and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the laser beam is irradiated successively for more than a certain number of times to machine the copper layer, then the copper layer can be completely removed, but delamination occurs at the boundary of the copper layer and the insulating layer
Solution Approach 1:
The patent applies periodic action by alternating between two different laser beams with different wavelengths (first laser beam and second laser beam) in a cyclic manner. The first laser beam machines the copper layer, and the second laser beam machines the insulating layer, preventing excessive heat accumulation that causes delamination while ensuring complete copper layer removal.
Solution Approach 2:
The patent changes the laser beam parameters by switching between two different wavelengths (first laser beam wavelength and second laser beam wavelength). This parameter change allows optimization of energy absorption for different materials (copper and insulating layer) and prevents harmful thermal effects like delamination.
2Manufacturing precision
If the laser beam is irradiated successively for more than a certain number of times to machine the insulating layer, then the insulating layer can be completely removed, but the hole shape becomes like a beer barrel
Solution Approach 1:
The patent applies periodic action by alternating between the first laser beam and the second laser beam. The second laser beam is specifically optimized for insulating layer machining with parameters that prevent excessive heat accumulation, maintaining straight hole sidewalls and preventing beer barrel shape formation.
Solution Approach 2:
The patent changes laser beam parameters by using the second laser beam with a wavelength optimized for insulating layer absorption. This parameter optimization prevents excessive heat accumulation and melting, maintaining proper hole geometry with straight sidewalls.
3Productivity
If the energy density is increased to efficiently machine the copper layer, then the machining speed increases, but the bottom of the copper layer melts and a through hole is made
Solution Approach 1:
The patent uses periodic alternation between the first laser beam (for copper layer machining) and the second laser beam (for insulating layer machining). This distributes the total energy input over time, preventing excessive heat accumulation at the hole bottom that would cause melting and through-hole formation, while maintaining efficient machining speed.
Solution Approach 2:
The patent changes laser beam parameters by switching between two different wavelengths optimized for different materials. This allows using higher energy density for copper layer machining without causing through-hole formation, as the second laser beam with different parameters is used for the insulating layer, distributing thermal load.
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 allows for precise machining with reduced delamination, overhang, and improved hole shape, while maintaining high efficiency by halving heat input and optimizing laser beam positioning, resulting in enhanced machining quality and speed.
Implementation Method 1
a beam splitter and acousto-optical elements to time-share the laser beams
Implementation Method 2
UV laser light is liable to be absorbed by many materials such as metals
Implementation Method 3
it can efficiently machine a copper layer for example even though the energy per one pulse is small by contracting an outer diameter of the laser beam and by increasing energy density per unit area
Implementation Method 4
machining holes on a workpiece by irradiating pulsed laser beams to the workpiece
Data Source
AI summary
There is provided a laser machining method and a laser machining apparatus whose machining accuracy and quality excel without lowering machining efficiency. One hole is machined by a split beam that is a first pulsed laser beam and another split beam that is a second pulsed laser beam whose irradiation position is determined based on irradiation position of the first laser beam. In this case, the machining quality may be improved by machining the circular hole by equalizing circling directions and angular velocity of the split beams. A beam splitter splits a laser beam outputted out of one laser oscillator into the split beams and AOMs can time-share them.