Glass Interposer Wiring with Smoothed Surface and Low Dishing
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Solution Overview
Problem
The challenges in designing a glass interposer include surface roughness issues due to processing methods like drilling, etching, and laser machining, which lead to microcracks, asperities, and stress concentration on wires, making it difficult to form fine wires reliably on glass substrates.
Innovation Solution
A wiring circuit substrate with a glass base, insulating resin layers, a first inorganic adhesive layer, through electrodes, and second conductive layers, where the glass base surface roughness is smoothed to 100 nm or less, and the conductive layers have minimal dishing, ensuring reliable wire formation and reduced stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If physical processing such as drilling or blasting is applied to form through-holes in glass substrate, then through-holes can be formed, but microcracks form or the glass substrate itself cracks due to tensile stress
Solution Approach 1:
The patent replaces mechanical drilling or blasting methods with laser beam processing to form through-holes in the glass substrate. This substitution eliminates the tensile stress and mechanical impact that cause microcracks and substrate failure, while still achieving effective through-hole formation for TSV structure creation.
Solution Approach 2:
The patent changes the processing parameters by using controlled laser beam energy and pulse duration to melt and evaporate glass material precisely. By adjusting laser parameters such as power density, scanning speed, and pulse width, the process achieves clean through-hole formation without generating excessive thermal stress or mechanical shock that would cause cracking.
2Manufacturing precision
If laser beam machining is used to form through-holes in glass substrate, then through-holes can be formed with high precision, but asperities form on the surface and stress concentrates on wires
Solution Approach 1:
The patent applies a preliminary action by forming a smooth insulating resin layer over the laser-processed glass substrate surface before depositing conductive wires. This resin layer acts as a stress-distributing medium that prevents stress concentration at asperities, enabling reliable wire formation while maintaining the precision benefits of laser machining.
Solution Approach 2:
The patent introduces an insulating resin layer as an intermediary between the laser-machined glass substrate and the conductive wire structure. This intermediary layer smooths out surface asperities and distributes mechanical stress, preventing wire breakage while preserving the precise through-hole geometry created by laser processing.
3Productivity
If high-density wiring is implemented on glass substrate, then connection density increases, but stress concentration on fine wires increases and reliability decreases
Solution Approach 1:
The patent uses an insulating resin layer as an intermediary matrix that embeds and supports fine conductive wires in high-density configurations. This resin layer distributes mechanical stress uniformly across the substrate, preventing stress concentration at wire locations even when wires are densely packed, thereby maintaining high connection density while ensuring wire reliability.
Solution Approach 2:
The patent creates a composite structure combining glass substrate, insulating resin, and conductive wires. The resin-glass composite provides mechanical support and stress distribution, while the conductive wires provide electrical connectivity. This composite approach enables high-density wiring while maintaining reliability through the synergistic properties of the combined materials.
Data Source
AI summary
A wiring circuit substrate includes a glass base, insulating resin layers, wire groups, a first inorganic adhesive layer, a through electrode, and second conductive layers. The glass base has a through-hole. The insulating resin layers are laminated to the glass base and each have a conductive via formed therein. The wire groups are laminated to the insulating resin layers. The first inorganic adhesive layer is laminated to the inner surface of the through-hole. The through electrode is formed of a first conductive layer laminated to the first inorganic adhesive layer. The second conductive layers are formed on the through electrode and the glass base and electrically connected to the upper and lower ends of the through electrode. The glass base has a surface roughness Ra of 100 nm or less, and the second conductive layers each have an amount of dishing of 5 μm or less above the through electrode.