Wiring Substrate with Mixed Laminate Methods for High-Frequency Signal Integrity
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Solution Overview
Problem
Existing wiring substrates face limitations in design flexibility and signal integrity for high-frequency signal transmission due to rigid conductor and insulating layer structures, which restrict the positioning and electrical characteristics of strip lines.
Innovation Solution
A wiring substrate design featuring a core substrate with alternating conductor and insulating layers, where the first laminate is formed without metal foils using an additive method and the second laminate is formed with metal foils using a subtractive or semi-additive method, allowing for different thicknesses and line widths of strip lines to match characteristic impedances and reduce planar size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rigid conductor and insulating layer structure is used in existing wiring substrates, then manufacturing process is simplified, but design flexibility and signal integrity for high-frequency signal transmission are limited
Solution Approach 1:
The patent divides the wiring substrate into two distinct laminate structures: a first laminate with conductor layers formed by additive method (without metal foil) and a second laminate with conductor layers formed by subtractive or semi-additive method (with metal foil). This segmentation allows each laminate to be optimized independently for different signal transmission requirements, thereby improving design flexibility while managing structural complexity through modular design.
Solution Approach 2:
The patent applies different formation methods to different regions of the wiring substrate. The first laminate uses additive method for specific conductor patterns requiring precise positioning and characteristic impedance control, while the second laminate uses subtractive or semi-additive methods for other regions. This local differentiation enables optimized signal integrity for high-frequency transmission in critical areas without unnecessarily complicating the entire substrate structure.
2Reliability
If conductor layers are formed with uniform thickness and line width, then manufacturing process is simplified, but characteristic impedance matching and signal integrity for high-frequency transmission are compromised
Solution Approach 1:
The patent employs parameter changes by forming conductor layers with varying thicknesses and line widths according to specific design requirements. The additive method enables precise control of conductor thickness and pattern geometry, while subtractive and semi-additive methods provide alternative parameter control for different regions. This allows optimization of characteristic impedance and signal integrity for high-frequency transmission without imposing uniform constraints across the entire substrate.
3Reliability
If the number of layers is increased to achieve desired characteristic impedances, then signal integrity improves, but planar size and device complexity increase
Solution Approach 1:
The patent achieves desired characteristic impedances by varying conductor layer parameters (thickness, line width, spacing) within existing laminate structures rather than simply increasing the number of layers. The additive method enables precise parameter control to achieve impedance matching with fewer layers, thereby maintaining signal integrity while minimizing planar size expansion.
Data Source
AI summary
A wiring substrate includes a substrate including conductor layers and core insulating layers, and a laminate including insulating layers and conductor layers such that the conductor layers include first layer including first line pattern. The laminate includes first strip line including the first pattern, a pair of interlayer insulating layers sandwiching the first pattern, and a pair of conductor layers sandwiching the interlayer layers, the conductor layers in the substrate include second layer including second line pattern such that the substrate includes second strip line including the second pattern, a pair of core insulating layers sandwiching the second pattern, and a pair of conductor layers sandwiching the core insulating layers, and the pair of core insulating layers is thicker than the pair of interlayer layers, the second pattern is thicker than the first pattern, and line width of the second pattern is larger than line width of the first pattern.