Wiring Board Coaxial Structure Impedance Control

Solution Overview

Problem

The challenge is to improve the accuracy of impedance control and reduce signal transmission loss in semiconductor packages, particularly in coaxial structures used in high-density and high-speed applications, where the diameter of connection lands and via shifts during processing make it difficult to maintain precise signal transmission characteristics.

Innovation Solution

A wiring board with a coaxial structure is developed, featuring inner and outer wiring parts connected via insulating resin, where the inner wiring part is electrically connected to component and circuit connection pads, and the outer wiring part is located on the peripheral surface, with specific diameter ranges for optimal impedance control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the diameter of the land is increased to allow for via shift during processing, then the via can be properly connected to the land, but the accuracy of impedance control deteriorates and transmission loss increases

Engineering Contradiction:

Improvevia connection reliabilityVSAvoidimpedance control accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The connection structure is divided into two distinct parts: a land on the circuit board and a separate pad on the wiring board. This segmentation allows each part to be optimized independently - the land can be larger for reliable via connection while the pad can be precisely controlled for impedance management, resolving the contradiction between connection reliability and impedance control accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the connection structure are given different properties. The land area is designed with larger dimensions to accommodate via shifts and ensure reliable connection, while the pad area is designed with precise dimensions for accurate impedance control. This local differentiation allows both requirements to be satisfied simultaneously without compromising either connection reliability or impedance precision.

Inventive Principle:

Principle #3Local quality

2Reliability

If the diameter of the land is increased to accommodate via shift, then connection reliability improves, but the formation of coaxial structures and precise signal transmission deteriorates

Engineering Contradiction:

Improvevia connection reliabilityVSAvoidcoaxial structure formation

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The connection structure is divided into two distinct parts: a land on the circuit board and a separate pad on the wiring board. This segmentation allows each part to be optimized independently - the land can be larger for reliable via connection while the pad can be precisely controlled for impedance management, resolving the contradiction between connection reliability and impedance control accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the connection structure are given different properties. The land area is designed with larger dimensions to accommodate via shifts and ensure reliable connection, while the pad area is designed with precise dimensions for accurate impedance control. This local differentiation allows both requirements to be satisfied simultaneously without compromising either connection reliability or impedance precision.

Inventive Principle:

Principle #3Local quality

3Volume of moving object

If the wiring board is made smaller for higher density, then package size is reduced, but the accuracy of impedance control and signal transmission deteriorates

Engineering Contradiction:

Improvepackage sizeVSAvoidimpedance control accuracy

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The pad dimensions are locally optimized with specific width and length parameters that maintain accurate impedance control even in compact packages. By differentiating the pad geometry from the land geometry and providing precise dimensional specifications for the pad, the invention enables small package size while preserving impedance control accuracy through locally tailored design parameters.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10187971B2Wiring board and method of manufacturing wiring board

Publication Date: 2019.01.22 SONY GROUP CORP

AI summary

A wiring board that includes: insulation layers and wiring layers which are laminated alternately; a component connection pad present on one surface of the wiring board in a lamination direction of the insulation layers and the wiring layers, and to which an electronic component is connected; a circuit connection pad present on another surface of the wiring board in the lamination direction and is connected to a circuit board; and a structure which includes a coaxial structure, wherein each of the wiring layers is connected by a via, and the coaxial structure includes an inner wiring part extending in the lamination direction and an outer wiring part located on a side corresponding to an outer peripheral surface of the inner wiring part through an insulating resin, and the inner wiring part is electrically connected to the component connection pad and the circuit connection pad.