Through-Glass Via Formation with Etch-Controlled Aspect Ratio
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Solution Overview
Problem
Existing methods for forming through-glass via-holes, such as laser drilling and chemical etching, face challenges in achieving precise aspect ratios, cleanliness of the via-hole surface, and efficient production, particularly for micro via-holes with diameters of 10 μm or less, due to issues like crack formation and high precision requirements.
Innovation Solution
A through-glass via-hole formation method involving laser-induced phase transition followed by chemical etching, using different concentrations of etching solutions to control the aspect ratio, where a deformed region is formed by laser irradiation below the ablation threshold and then selectively etched to create via-holes with precise dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser drilling is used to form via holes through glass substrate, then via holes can be formed through the substrate, but the via holes have poor surface cleanliness and may develop cracks during machining
Solution Approach 1:
The via hole formation process is divided into two distinct stages: first, laser irradiation creates a deformed region within the glass substrate without removing material; second, chemical etching selectively removes the deformed region to form the final via hole. This segmentation allows each process to be optimized independently, achieving clean surfaces without cracks.
Solution Approach 2:
The laser-induced deformed region acts as an intermediary that facilitates selective chemical etching. The deformed region has different chemical reactivity compared to the surrounding glass, enabling the etching solution to selectively remove only the laser-modified areas and form clean via holes.
2Ease of manufacture
If laser drilling is used to machine multiple via holes, then via holes can be formed, but the process is time consuming and production cost increases with number of via holes
Solution Approach 1:
The laser irradiation step performs preliminary action by creating deformed regions in all desired via hole locations simultaneously or in rapid succession. The subsequent chemical etching then completes the via holes in batch, dramatically improving productivity compared to sequential drilling while maintaining ease of manufacture.
3Ease of manufacture
If chemical etching is used to form via holes, then via holes can be formed through the substrate, but the aspect ratio cannot be precisely controlled due to taper angle
Solution Approach 1:
The laser irradiation creates localized deformed regions with specific spatial distribution and morphology. By controlling the laser parameters and irradiation pattern, the deformed region's cross-sectional area and shape are precisely defined, which directly determines the final via hole's aspect ratio. The chemical etching then faithfully reproduces this predefined geometry, achieving precise aspect ratio control.
4Measurement precision
If laser drilling is used to form micro via holes with diameter of 10 μm or less, then via holes can be formed, but machining precision deteriorates and cracks occur
Solution Approach 1:
The mechanical laser drilling process is replaced with a chemical etching process that acts on laser-prepared deformed regions. This substitution eliminates the mechanical stresses and thermal damages that cause cracks in traditional laser drilling, while maintaining the ability to precisely form micro via holes with diameters of 10 μm or less.
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 enables the formation of micro via-holes with clean, smooth surfaces and precise aspect ratios without physical drilling, reducing production time and costs by leveraging the differential etching velocities of deformed and non-deformed regions.
Implementation Method 1
forming a hole-shaped deformed region extending in a thickness direction of a glass substrate by irradiating the glass substrate with a laser beam at an energy intensity not exceeding an ablation threshold of the glass substrate
Implementation Method 2
forming a via-hole through the glass substrate along the deformed region by immersing the glass substrate in an etching solution such that the deformed region is etched and removed
Data Source
AI summary
A through-glass via-hole formation method includes: forming a hole-shaped deformed region extending in a thickness direction of a glass substrate by irradiating the glass substrate with a laser beam at an energy intensity not exceeding an ablation threshold of the glass substrate; and forming a via-hole through the glass substrate along the deformed region by immersing the glass substrate in an etching solution such that the deformed region is etched and removed, wherein an etching solution having a first concentration is used as the etching solution to allow the via-hole to have a first aspect ratio, and an etching solution having a second concentration greater than the first concentration is used as the etching solution to allow the via-hole to have a second aspect ratio smaller than the first aspect ratio.