Resin Substrate Gap Design for Via Conductor Stress Distribution

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Solution Overview

Problem

Conventional resin substrates are prone to cracking and peeling at the boundary of interlayer connection conductors and conductor patterns due to external stress, heat, or bending, leading to structural fragility and breakage.

Innovation Solution

Incorporating a gap adjacent to the bonding portion of the interlayer connection conductor and conductor pattern, which distributes stress and reduces the likelihood of peeling or cracking, while ensuring the interlayer connection conductor contacts the resin body to further mitigate stress concentration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a via conductor penetrates the insulating base material to connect conductor patterns, then electrical connection between layers is achieved, but stress concentration occurs at the via conductor boundary causing cracking and peeling under external shock or bending stress

Engineering Contradiction:

Improvebonding strength between via conductor and conductor patternVSAvoidresistance to cracking and peeling at via conductor boundary

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

A gap is provided between the via conductor and the conductor pattern before external stress is applied. This gap acts as a cushioning space that absorbs and distributes stress, preventing stress concentration at the bonding boundary. The gap is formed by controlling the etching depth to be less than the thickness of the insulating base material, creating a protective void space that mitigates the impact of external shocks and bending stresses on the bonding interface.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If the via conductor is made to penetrate completely through the insulating base material, then direct connection between conductor patterns is achieved, but the acute angle formed at the boundary makes the structure vulnerable to breakage

Engineering Contradiction:

Improveelectrical connection stabilityVSAvoidstructural vulnerability at via conductor boundary

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The insulating base material has different properties in different regions: the etched portion creates a localized cavity around the via conductor while the rest of the material maintains its original structural integrity. This local modification allows the via conductor to be embedded in the insulating base material without forming a vulnerable acute angle boundary, as the etched cavity provides a transition zone that distributes stress more evenly.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11291110B2Resin substrate and electronic device

Publication Date: 2022.03.29 MURATA MFG CO LTD

AI summary

A resin substrate includes a resin body, an interlayer connection conductor provided in the resin body, and a conductor pattern bonded to the interlayer connection conductor. The resin body includes a gap provided adjacent to or in a vicinity of a bonding portion of the interlayer connection conductor and the conductor pattern, and a contact portion that contacts the interlayer connection conductor.