Laser-Machined Micro-Via Substrate for High-Speed Signal Integrity
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Solution Overview
Problem
Conventional micro-via structures formed using laser techniques suffer from varying distances between curved conductive layers, leading to decreased coupling capacity, increased reflection of high-speed signals, and noise interference due to changes in characteristic impedance.
Innovation Solution
A substrate with a micro-via structure featuring a first and second conductive column, each comprising a flat and cambered conductive layer with a dielectric layer in between, and a differential signal pair with traces connected to these layers, maintaining a constant distance between traces to stabilize impedance and reduce noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional laser technique is used to form micro-via structure, then the micro-via can be formed on the substrate, but the distance between conductive layers varies causing decreased coupling capacity and increased signal reflection
Solution Approach 1:
The conductive column is segmented into multiple conductive layers (first conductive layer, second conductive layer, third conductive layer) separated by dielectric layers. This segmentation allows each layer to be precisely positioned and controlled, ensuring constant distance between adjacent conductive layers throughout the micro-via structure, thereby maintaining consistent coupling capacity and characteristic impedance for differential signals.
Solution Approach 2:
Different regions of the micro-via structure are assigned different properties: the first and second conductive layers are positioned at specific depths with precise spacing to maintain constant distance for differential signal transmission, while the third conductive layer provides additional shielding or grounding functions. The dielectric layers are specifically positioned between conductive layers to maintain precise spacing and provide electrical isolation.
2Reliability
If the distance between traces of differential signal pair is reduced to increase coupling capacity, then common mode noise suppression is improved, but the characteristic impedance becomes unstable due to varying distances in conventional structures
Solution Approach 1:
The conductive column is divided into multiple conductive layers with dielectric layers in between, allowing the first and second conductive layers to be positioned at optimized distances from each other to maximize coupling capacity for noise suppression, while the third conductive layer provides additional reference plane to stabilize characteristic impedance throughout the vertical structure.
Solution Approach 2:
The solution moves from a two-dimensional planar trace structure to a three-dimensional stacked conductive layer structure. By adding the vertical dimension with multiple conductive layers separated by dielectric layers, the patent achieves both close spacing for coupling (in the vertical dimension) and stable impedance reference (through the third conductive layer), resolving the contradiction between coupling capacity and impedance stability.
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 solution maintains constant coupling capacity and reduces noise interference by ensuring consistent characteristic impedance, effectively minimizing signal reflection and phase shifts during high-speed signal transmission.
Implementation Method 1
Because the heat inputted by the laser beams is highly more than the heat reflected, transmitted or spread by the materials, the materials are heating very fast and evaporating to form a micro-via
Data Source
AI summary
A substrate to which a laser technique is applied includes a signal layer, a micro via structure, and a differential signal pair. The micro via structure is divided into a first conductive column and a second conductive column after a laser-cutting step. The first conductive column includes a first flat conductive layer, and the second conductive column includes a second flat conductive layer. A first trace of the differential signal pair is parallel to and electrically connected to the first flat conductive layer. A second trace of the differential signal pair is parallel to and electrically connected to the second flat conductive layer. The distance between the first trace and the second trace is the same as the distance between the first flat conductive layer and the second flat conductive layer. The reflection of high-speed signals and the noise interferences can be reduced.