Glass Microhole Drilling Using Laser Defect Lines and Etching
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Solution Overview
Problem
Current methods for forming holes in glass for electronic interposers face challenges such as low quality, slow rates, and high costs due to limitations in hole formation techniques like hot pressing, electrical discharge drilling, and laser drilling, particularly in achieving small dimensions and high precision.
Innovation Solution
A method using a picosecond pulsed laser with a specialized optical delivery system to create damage tracks or pilot holes, followed by acid etching to enlarge them, enabling faster and more cost-effective production of high-quality holes suitable for interposers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser drilling is used to form holes in glass, then manufacturing precision is improved, but productivity deteriorates (slow drilling rate)
Solution Approach 1:
The hole formation process is divided into two distinct stages: first, laser drilling creates precise pilot holes with high manufacturing precision; second, chemical etching enlarges these pilot holes to the final required dimensions. This segmentation allows each process to be optimized independently - laser drilling for precision and chemical etching for speed - thereby resolving the contradiction between hole quality and drilling rate.
Solution Approach 2:
The laser drilling process performs preliminary action by creating small pilot holes that serve as templates for the subsequent chemical etching process. These pre-formed pilot holes ensure precise positioning and dimensional control before the enlargement step, maintaining manufacturing precision while enabling faster overall production through the parallel processing capability of chemical etching.
2Manufacturing precision
If traditional laser drilling methods are used, then manufacturing precision is maintained, but loss of time increases (time-consuming process)
Solution Approach 1:
The process is segmented into laser pilot hole formation and chemical etching enlargement. The laser component maintains manufacturing precision by creating accurate pilot holes, while the chemical etching component reduces loss of time by rapidly enlarging holes in parallel, achieving both precision and speed.
Solution Approach 2:
The pilot hole acts as an intermediary structure between the laser drilling process and the final hole requirement. It carries the precision information from laser drilling while enabling the time-efficient chemical etching enlargement process to achieve the final dimensions, thereby reducing overall process time without sacrificing precision.
3Manufacturing precision
If precision laser drilling platform is used, then manufacturing precision is improved, but device complexity increases (capital cost)
Solution Approach 1:
The system is segmented into a relatively simple laser drilling unit for pilot hole creation and a chemical etching system for hole enlargement. This segmentation reduces device complexity compared to a single high-precision laser drilling system that would be needed to drill final-size holes directly, while maintaining manufacturing precision through the two-stage process.
Solution Approach 2:
The pilot holes are essentially temporary structures that serve their purpose of defining hole locations and dimensions, then are enlarged by chemical etching. This approach uses a simpler, less expensive laser system for the preliminary pilot hole formation rather than requiring a complex high-precision laser system capable of drilling final-size holes directly, thereby reducing device complexity and capital cost.
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 significantly faster hole formation rates, achieving hole diameters from less than 20 microns to tens of microns with improved quality and lower production costs compared to traditional methods, enabling efficient production of interposers for electronic applications.
Implementation Method 1
A laser is used to make about 10 micron diameter pilot holes using multiple (e.g., hundreds) of laser pulses per hole
Implementation Method 2
the part is etched with acid to enlarge the holes and achieve the target dimensions
Data Source
AI summary
Forming holes in a material includes focusing a pulsed laser beam into a laser beam focal line oriented along the beam propagation direction and directed into the material, the laser beam focal line generating an induced absorption within the material, the induced absorption producing a defect line along the laser beam focal line within the material, and translating the material and the laser beam relative to each other, thereby forming a plurality of defect lines in the material, and etching the material in an acid solution to produce holes greater than 1 micron in diameter by enlarging the defect lines in the material. A glass article includes a stack of glass substrates with formed holes of 1-100 micron diameter extending through the stack.