Core Substrate Trench Vias for Fine-Pitch Thick Package Cores
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Solution Overview
Problem
Existing microelectronic packages face challenges in creating small diameter and fine pitch vias across thick cores, leading to excessive parasitics, impedance discontinuities, low via density, and low integration, frequency, and bandwidth densities due to mechanical drilling processes.
Innovation Solution
Laser-assisted etching process is used to pattern core substrates made of materials like glass, ceramic, or silicon, allowing for the formation of crack-free, high-density via holes with diameters as small as 10 μm and pitches of 40 μm or smaller, and enabling the creation of through and blind vias with sloped or hourglass-shaped sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional mechanical drilling methods are used to create vias in thick cores, then the manufacturing process is simple and straightforward, but the via diameter cannot be made small and the pitch cannot be made fine, resulting in low via density
Solution Approach 1:
The patent replaces traditional mechanical drilling methods with laser-assisted patterning and etching processes. The laser system enables precise formation of small diameter vias with fine pitch through optical focusing and controlled material removal, eliminating the mechanical constraints that limited via size and spacing in conventional drilling approaches.
Solution Approach 2:
The patent changes the fundamental parameters of the via formation process by transitioning from mechanical force-based drilling to laser-based thermal and optical processing. This enables via diameters of 10 micrometers or less and pitches below 50 micrometers, representing a significant improvement in dimensional precision and density compared to mechanical methods.
2Quantity of substance
If via diameter is reduced to increase via density, then integration density and bandwidth density improve, but parasitics increase and impedance discontinuities occur
Solution Approach 1:
The patent applies local quality by creating via planes - extended planar regions of high via density - in specific locations within the core substrate. This allows concentration of via density where needed for high bandwidth density while maintaining controlled impedance characteristics in other regions. The laser-assisted process enables precise control of via placement and density distribution throughout the core.
Solution Approach 2:
The patent transitions from traditional point-like vias to planar via structures with extended surface area. Via planes provide a two-dimensional conductive structure that reduces current density concentration, thereby reducing parasitic effects while maintaining high integration density. This dimensional transformation from 0D via points to 2D via planes resolves the contradiction between density and parasitics.
3Stability of the object's composition
If thick core is used to reduce package warpage, then structural stability improves, but creating small diameter and fine pitch vias across the thick core becomes challenging
Solution Approach 1:
The patent replaces mechanical drilling with laser-assisted patterning and etching, which can precisely form vias through thick core materials without the mechanical tool wear, alignment errors, and force limitations that plague conventional drilling. The laser process maintains consistent precision regardless of core thickness, enabling via formation in thick cores while preserving structural stability.
Solution Approach 2:
The patent uses laser-assisted patterning to pre-form precise via patterns and trenches in the core substrate before final via fabrication. This preliminary structuring enables accurate positioning and consistent geometry of vias through thick cores, establishing a template that guides subsequent processing steps and ensures manufacturing precision throughout the thick substrate.
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
The laser-assisted etching process enhances via density and reduces parasitics, improving integration, frequency, and bandwidth densities by allowing for smaller via diameters and pitches, thus enhancing the performance of package substrates.
Implementation Method 1
A laser is used to irradiate and heat a glass core to a melting and/or evaporation point
Implementation Method 2
A laser is used to irradiate and heat a glass core to a melting and/or evaporation point
Implementation Method 3
A laser is used to irradiate and heat a glass core to a melting and/or evaporation point
Data Source
AI summary
Embodiments disclosed herein comprise package substrates and methods of forming package substrates. In an embodiment, a package substrate comprises a core substrate. A hole is disposed into the core substrate, and a via is disposed in the hole. In an embodiment, the via completely fills the hole. In an embodiment, a method of forming a package substrate comprises exposing a region of a core substrate with a laser. In an embodiment, the laser changes the morphology of the exposed region. The method may further comprise etching the core substrate, where the exposed region etches at a faster rate than the remainder of the core substrate to form a hole in the core substrate. The method may further comprise disposing a via in the hole.