Internally Routed Flexible Circuits to Prevent Joint Cracking

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing flexible hybrid electronics manufacturing methods face challenges in reliably and accurately registering and connecting semiconductor dies to printed traces, particularly at the sensitive neck regions where bending and stretching strains cause cracks and failures.

Innovation Solution

The solution involves routing electrically conductive traces and vias internally across the flexible substrate, positioning the neck regions away from the edge of the rigid circuit component to protect them from strain, and using smooth transitions at the junctions to reduce stress concentration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If semiconductor dies are connected to printed traces at edge regions, then registration and connection can be achieved, but the neck regions are exposed to bending and stretching strains causing cracks and failures

Engineering Contradiction:

Improveconnection reliabilityVSAvoidbending and stretching strain

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent moves the connection interface from the edge region (2D boundary) to the interior region (2D area) of the semiconductor die, effectively changing the spatial dimension of connection placement. This internal routing approach positions neck regions away from strain-prone edge areas, reducing exposure to bending and stretching strains while maintaining reliable electrical connections between semiconductor dies and printed traces

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If neck regions are positioned at the edge of circuit components, then manufacturing and registration are simplified, but the neck regions are vulnerable to cracking under mechanical strain

Engineering Contradiction:

Improveregistration simplicityVSAvoidneck region strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent relocates neck regions from the edge boundary to the interior area of circuit components. This dimensional relocation maintains manufacturing feasibility through internal routing while significantly improving neck region strength by positioning them away from strain-concentrated edge areas, preventing cracks under mechanical bending and stretching

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent proactively positions neck regions in interior areas before mechanical strain occurs, creating a protective configuration that cushions these vulnerable regions from edge-related stresses. This preemptive placement prevents strain concentration and crack initiation, ensuring durability without complicating the manufacturing process

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS20250343154A1Flexible Electronic Devices Including Internally Routed Channels

Publication Date: 2025.11.06 3M INNOVATIVE PROPERTIES CO

AI summary

Devices are provided to include a flexible substrate and a rigid circuit component attached to the flexible substrate. The substrate provides electrically conductive traces and vias connected to contact pads at edges of the rigid circuit component to form electrical joints or junctions. The electrical joints or junctions are located and/or shaped to prevent cracks in the traces upon bending or stretching of the device.