Glass Substrate Through-Hole Drilling with Laser and Wet Etching
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Solution Overview
Problem
Carbon dioxide laser processing methods for drilling holes in glass substrates often result in cracks and compromised plating adhesion properties due to residual stress and uneven hole diameters.
Innovation Solution
A method involving the formation of a blind hole using a carbon dioxide laser with a protective sheet, followed by annealing and hydrofluoric acid wet-etching to minimize residual stress and enhance plating adhesion, while maintaining a controlled etching process to achieve a through hole with improved dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a carbon dioxide laser is used to drill a hole through the entire glass substrate, then productivity is improved, but cracks form in the glass substrate due to residual stress
Solution Approach 1:
The drilling process is divided into two stages: first forming a blind hole (partial depth) with the carbon dioxide laser, then completing the through-hole formation through chemical etching. This segmentation allows the laser to operate at high power without causing cracks, while the chemical etching finishes the hole without inducing stress.
Solution Approach 2:
A protective sheet is introduced as an intermediary element during the laser drilling process. The sheet is adhered to the glass substrate surface, and the laser drills through the sheet to form a blind hole. The sheet prevents molten glass from adhering to the substrate surface and reduces residual stress, thereby preventing crack formation.
2Reliability
If a blind hole is formed by laser processing without irradiating the entire through hole, then crack formation is prevented, but the hole diameter on the non-irradiated side is smaller resulting in decreased plating adhesion properties
Solution Approach 1:
Hydrofluoric acid chemical etching is introduced as a mediator to enlarge the hole diameter on the non-irradiated side. The protective sheet is selectively removed from the non-irradiated side, allowing the acid to etch and expand the blind hole opening to the desired diameter, ensuring uniform plating adhesion properties throughout the through hole.
3Reliability
If the protective sheet is removed and annealing treatment is performed, then residual stress is reduced, but additional processing time is required
Solution Approach 1:
The annealing treatment is merged with the chemical etching process by performing both operations in sequence without intermediate cooling or setup time. The protective sheet is removed, annealing is applied to reduce residual stress, and immediately followed by hydrofluoric acid etching to complete the through-hole formation, thereby minimizing total processing time.
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 effectively prevents cracks and enhances plating adhesion by alleviating residual stress and enlarging the hole diameter on the non-irradiated side, improving the overall quality of the drilled holes.
Implementation Method 1
irradiating a carbon dioxide laser onto a drilling position on the glass substrate so as to form a blind hole
Implementation Method 2
performing an annealing treatment
Implementation Method 3
performing a polishing process on a side of the glass substrate not irradiated with the laser with using hydrofluoric acid so as to convert the blind hole into a through hole
Data Source
Figure 1A~1E
Figure 2
AI summary
Provided is a laser processing method for drilling a hole (4) in a glass substrate (1) with using a carbon dioxide laser, including the steps of: irradiating the laser onto a drilling position on the glass substrate (1) from a side of the glass substrate (1) on which a protective sheet is adhered so as to form a blind hole (4) ; removing the protective sheet from the glass substrate (1) and performing an annealing treatment; and performing a wet-etching process on a side of the glass substrate (1) not irradiated with the laser so as to convert the blind hole (4) into a through hole (4).