Glass Core Half Alignment for Defect-Free High-Aspect TGVs
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Solution Overview
Problem
Existing electronic packaging architectures face challenges in forming high aspect ratio through glass vias (TGVs) in glass core substrates, as the narrow midpoints of these vias lead to plating defects and voids, particularly in thick glass cores, which diminish their performance.
Innovation Solution
The use of aligned glass sub-layers with alignment features such as protrusions and recesses or alignment vias and notches allows for the formation of lower aspect ratio TGVs that can be coupled to achieve high aspect ratios, enabling proper plating without defects, using techniques like laser-assisted patterning and diffusion bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If dual sided laser exposure is used to form TGVs in thick glass cores, then the glass core thickness can be increased, but the via opening develops a narrow middle region that causes plating difficulties and defects
Solution Approach 1:
The glass core is divided into two separate sub-layers, each with its own TGV formation process. This segmentation allows each layer to have a more uniform via opening that can be properly plated, while the combined structure achieves the desired thick glass core. The alignment features (protrusions and recesses) enable precise registration between the two sub-layers.
2Length of moving object
If the via opening middle region is made narrow to achieve high aspect ratio, then the glass core thickness can be increased, but plating voids and defects occur that diminish TGV performance
Solution Approach 1:
By segmenting the thick glass core into two sub-layers, each TGV in the sub-layers has a lower aspect ratio with a more uniform opening. This prevents plating voids and defects while achieving the overall high aspect ratio when the sub-layers are combined. Each segment can be independently optimized for proper plating.
Solution Approach 2:
The solution moves from a single vertical dimension problem (high aspect ratio TGV in one thick layer) to a two-dimensional solution (two thinner layers stacked together). This dimensional change allows each layer to have optimal via dimensions for plating while achieving the desired overall thickness.
3Manufacturing precision
If the glass core is split into multiple sub-layers to reduce via aspect ratio, then plating quality improves, but alignment precision between sub-layers becomes challenging
Solution Approach 1:
Alignment features (protrusions and recesses) are formed in advance during the TGV fabrication process in each sub-layer. These pre-formed features serve as mechanical guides that automatically ensure precise alignment when the sub-layers are bonded together, eliminating the need for complex post-alignment procedures.
Solution Approach 2:
The alignment features are self-aligning mechanical structures where the protrusion in one sub-layer fits into the recess of the other sub-layer. This self-service alignment mechanism ensures precise registration without requiring external alignment equipment or complex procedures.
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 enables the creation of high aspect ratio TGVs with improved plating quality, reducing voids and defects, and allowing for the fabrication of thicker glass cores with enhanced performance.
Implementation Method 1
a laser exposure is used to modify the microstructure and/or phase of the glass
Implementation Method 2
modify the microstructure and/or phase of the glass
Implementation Method 3
the first TGV extends past a surface of the first glass sub-layer and is inserted into an opening of the second TGV
Implementation Method 4
using techniques like laser-assisted patterning and diffusion bonding
Data Source
AI summary
Embodiments disclosed herein include cores for package substrates. In an embodiment, the core comprises a first substrate, where the first substrate comprises glass. In an embodiment, the core further comprises a first through glass via (TGV) through the first substrate and a second substrate, where the second substrate comprises glass. In an embodiment, the core further comprises a second TGV through the second substrate, where the first TGV is aligned with the second TGV.