Glass-Core PCB Through-Via Structure for Warpage Control
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Solution Overview
Problem
Printed circuit boards face issues with warpage due to low modulus and high thermal expansion, limiting the implementation of microcircuits and requiring materials that can suppress warpage while reducing process complexity and costs.
Innovation Solution
Embedding a glass layer in an insulating layer to form a through-hole and via conductor, with a shifted region on the wall surface to manage thermal and mechanical stress, allowing for reduced process steps and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If copper clad laminate (CCL) is used as a core layer, then the printed circuit board can be manufactured, but warpage occurs due to low modulus and high coefficient of thermal expansion
Solution Approach 1:
The patent uses a glass layer as a core layer instead of traditional CCL. The glass layer has higher modulus and lower coefficient of thermal expansion compared to CCL, thereby suppressing warpage and improving structural stability. This composite material approach replaces the problematic CCL core with a glass-based core that provides the necessary mechanical properties.
Solution Approach 2:
The patent changes the material parameters of the core layer by using glass layer with different physical properties (higher modulus, lower thermal expansion coefficient) compared to CCL. This parameter change directly addresses the warpage issue by selecting materials with superior mechanical and thermal stability characteristics.
2Stability of the object's composition
If a new material core layer is used to suppress warpage, then warpage control is improved, but the number of processes increases and costs increase
Solution Approach 1:
The patent embeds the glass layer within the insulating layer structure, merging the core layer function with the insulating layer. This integration allows forming a through-hole through a single process that penetrates both the insulating layer and glass layer simultaneously, reducing the number of separate manufacturing steps compared to traditional multi-layer approaches.
Solution Approach 2:
The glass layer serves multiple functions: it acts as a core layer for structural support, provides insulation, and enables through-hole formation. This multi-functionality reduces the need for separate dedicated core layers and simplifies the overall manufacturing process.
3Reliability
If a through-hole is formed through traditional processes, then connection between layers is achieved, but process stability is compromised and via reliability is reduced
Solution Approach 1:
The glass layer is embedded in the insulating layer before through-hole formation. This preliminary embedding ensures proper alignment and structural support, allowing the subsequent through-hole formation to proceed with greater stability and precision, thereby improving via reliability.
Solution Approach 2:
The combination of glass layer and insulating layer creates a composite structure that provides both mechanical stability and proper insulation during through-hole formation. This composite structure ensures process stability while maintaining via reliability through the inherent properties of glass material.
Data Source
AI summary
A printed circuit board includes a glass layer; a first insulating layer covering each of an upper surface and a lower surface of the glass layer; a first conductor layer disposed on an upper surface of the first insulating layer; a second conductor layer disposed on a lower surface of the first insulating layer; and a through-hole penetrating between the first and second conductor layers, and a through-via including a via conductor disposed in the through-hole and connected to the first and second conductor layers, wherein a wall surface of the through-hole has at least one shifted region.