Glass Wiring Board Through-Via Process for Thin Substrate Reliability
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Solution Overview
Problem
The formation of through vias in glass substrates with a thickness of 300 μm or less leads to reduced mechanical strength, making handling difficult, and existing methods like dry etching are time-consuming and challenging, with issues such as etching residue adhesion and increased electrical resistance affecting the reliability and transmission characteristics of the wiring boards.
Innovation Solution
A method involving laser modification of glass substrates, formation of a hydrofluoric acid resistant metal film and copper layer, etching to create through vias, and a through via treatment to remove residues, ensuring stable connections and improved electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If through vias are formed in glass substrates with thickness of 300 μm or less, then the wiring board can be manufactured with smaller size and higher integration, but the mechanical strength of the glass substrate is reduced making handling difficult
Solution Approach 1:
A support substrate is bonded to the glass substrate before through via formation. This preliminary action provides mechanical support during the via formation process, preventing substrate breakage while enabling thin substrate design. The support substrate is removed after via formation completes its supporting function.
Solution Approach 2:
The support substrate acts as an intermediary element that temporarily reinforces the thin glass substrate during the vulnerable via formation process. This mediator provides the necessary mechanical strength without becoming part of the final product structure.
2Manufacturing precision
If dry etching is used to form through vias in glass substrates, then the via formation can be achieved, but the process is time-consuming and etching residues adhere to the substrate increasing electrical resistance
Solution Approach 1:
Laser processing replaces the mechanical/chemical dry etching process. The laser directly ablates the glass material to form through vias without requiring chemical etchants, significantly reducing process time and eliminating etching residue formation that would increase electrical resistance.
Solution Approach 2:
The method changes the processing parameters from chemical etching to laser ablation, fundamentally altering the material removal mechanism. This parameter change eliminates the residue adhesion problem and reduces processing time while maintaining via formation quality.
3Reliability
If through vias are formed in glass substrates, then connectivity between wiring layers is achieved, but etching residues adhere to the hydrofluoric acid resistant metal film increasing electrical resistance and reducing reliability
Solution Approach 1:
Laser processing replaces chemical etching, eliminating the source of etching residues. The laser ablation process removes glass material cleanly without generating residues that would adhere to the metal film and increase electrical resistance, thereby improving connection reliability.
Solution Approach 2:
The invention converts the potential harm of residue adhesion into a benefit by using laser processing that inherently prevents residue formation. The clean laser ablation process transforms the etching step from a harmful residue-generating process into a clean material removal process.
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
Enables easy and cost-effective manufacturing of wiring boards with good transmission and electrical characteristics, addressing the mechanical strength and reliability issues of glass substrates with through vias.
Implementation Method 1
a step A of forming a laser-modified portion in a glass substrate by applying laser light to the glass substrate from a first surface toward an opposite surface
Implementation Method 2
a step C of etching a surface of the glass substrate opposite to the first surface to form a through via in the laser-modified portion
Data Source
AI summary
A wiring board manufacturing method including a step A of forming a laser-modified portion in a glass substrate by applying laser light to the glass substrate from a first surface toward an opposite surface thereof; a step B of forming, on the first surface of the glass substrate, a first surface wiring layer including a hydrofluoric acid resistant metal film and a copper layer; a step C of etching a surface of the glass substrate opposite to the first surface to form a through via in the laser-modified portion and form a second surface of the glass substrate, the second surface being an opposite surface to the first surface; a through via treatment step D of removing an etching residue of glass adhered to the hydrofluoric acid resistant metal film; and a step E of forming a through electrode in the through via.