Lead Pin Bridge Substrate Layout for 70 GHz Impedance Matching

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Solution Overview

Problem

Existing high-frequency line connecting structures face challenges in suppressing impedance mismatch between bridge substrates and printed circuit boards, particularly when mounting components like DC block capacitors, which affects the wide bandwidth performance from DC to 70 GHz.

Innovation Solution

The proposed high-frequency line connecting structure involves a configuration where a first substrate with a first high-frequency line and a second substrate with a second high-frequency line and lead pins are mounted. The lead pins, composed of signal and ground lead pins, are designed such that the height of the ground lead pins is greater than that of the signal lead pins, ensuring the ground lead pins surround the signal lead pins, thereby maintaining capacitance and suppressing characteristic impedance increase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the length of open stub is shortened by back drilling, then the stub resonance frequency shifts to high frequency, but the manufacturing cost increases due to high-precision processing requirements

Engineering Contradiction:

Improvehigh-frequency characteristicsVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention extracts and removes the open stub structure entirely by using a bridge substrate configuration where high-frequency lines are routed through a separate substrate layer, eliminating the need for back drilling and the associated high-precision manufacturing requirements while maintaining stub resonance suppression

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention transitions from a planar two-dimensional PCB layout to a three-dimensional multi-layer structure by introducing a bridge substrate that routes high-frequency lines through a separate layer, allowing lines to cross without intersection and eliminating open stubs without requiring precise back drilling

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If bridge substrate is used to cross high-frequency lines three-dimensionally, then bandwidth is extended, but impedance mismatch occurs at connection portions

Engineering Contradiction:

ImprovebandwidthVSAvoidimpedance matching

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention applies local quality by creating a ground lead pin structure with different dimensions than signal lead pins, where ground lead pins have larger cross-sectional area and extend closer to the bridge substrate, providing localized impedance control and matching at the connection portions between bridge substrate and PCB

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention changes the geometric parameters of lead pins, specifically making ground lead pins larger than signal lead pins and positioning them closer to the bridge substrate, thereby adjusting the electrical characteristics to achieve impedance matching while maintaining extended bandwidth

Inventive Principle:

Principle #35Parameter changes

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 configuration achieves impedance matching between the high-frequency lines of the bridge substrate and the printed circuit board, resulting in low reflection loss, passage loss, and crosstalk characteristics across a wide bandwidth from DC to 70 GHz.

Implementation Method 1

the height of the ground lead pins is greater than that of the signal lead pins, ensuring the ground lead pins surround the signal lead pins, thereby maintaining capacitance and suppressing characteristic impedance increase

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS12278413B2High-frequency line structure with lead pin-connected substrates

Publication Date: 2025.04.15 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

A high-frequency line substrate is mounted on a printed circuit board. The printed circuit board includes a first high-frequency line. The high-frequency line substrate includes a second high-frequency line and lead pins that connect the first high-frequency line and the second high-frequency line. At the contact portions between the signal lead pins and the second high-frequency line of the high-frequency line substrate, and at the contact portions between the ground lead pins and the second high-frequency line of the high-frequency line substrate, the height of the ground lead pins from an upper surface of the printed circuit board is greater than the height of the signal lead pins.