Fiber Array Package With Glass Sheath for Hermetic Strain Relief

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Solution Overview

Problem

Conventional optical fiber connectors face challenges in achieving reliable strain relief and hermetic sealing due to material mismatch in thermal expansion coefficients and epoxy shrinkage, which can lead to detachment of fibers from the substrate and optical aberrations, failing to meet telecommunications testing standards like 85/85 and −40 testing.

Innovation Solution

A sealed fiber array package is designed with a glass sheath that separates strain relief and hermetic sealing functions, using epoxy only at spatially separated ends to bond the sheath to the substrate and fibers, eliminating epoxy contact with the weld interface and utilizing a CTE-matched glass sheath to prevent expansion mismatch.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If epoxy is used to join optical fibers to substrate and form seals, then hermetic sealing and strain relief are achieved, but material mismatch in thermal expansion coefficients and epoxy shrinkage cause fiber detachment and optical aberrations

Engineering Contradiction:

Improvehermetic sealing reliabilityVSAvoidfiber-to-substrate joint precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent divides the sealing function into two separate components: a hermetic seal formed by bonding the sheath to the substrate, and a strain relief function provided by the sheath surrounding the fiber array. This segmentation eliminates the need for epoxy to simultaneously provide both hermetic sealing and strain relief, preventing the conflicts between these functions that cause fiber detachment and optical aberrations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The glass sheath acts as an intermediary structure between the optical fibers and the substrate. It provides hermetic sealing through its bonding to the substrate while simultaneously providing strain relief through its surrounding of the fiber array. This intermediary structure eliminates the need for epoxy to directly bond fibers to the substrate, resolving the conflict between hermetic sealing and maintaining fiber joint precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If epoxy is used to bond fiber to substrate, then strain relief is provided, but epoxy shrinkage and CTE mismatch lead to static fatigue and reduced joint lifetime

Engineering Contradiction:

Improvestrain relief capabilityVSAvoidwelded joint lifetime

Core Design Contradiction:

StrengthVSDuration of action of stationary object

Solution Approach 1:

The patent extracts the strain relief function from the epoxy bonding and assigns it to the glass sheath. By removing epoxy from the strain relief function and keeping it only for hermetic sealing, the patent eliminates the harmful effects of epoxy shrinkage and CTE mismatch that cause static fatigue and reduce joint lifetime.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The glass sheath provides homogeneous material properties throughout the structure, with uniform CTE matching the optical fibers. This homogeneity eliminates the heterogeneous material interfaces between epoxy and glass components that cause stress concentration and static fatigue, thereby extending welded joint lifetime.

Inventive Principle:

Principle #33Homogeneity

3Reliability

If epoxy is used for sealing, then hermetic barrier is formed, but epoxy shrinkage causes optical aberrations

Engineering Contradiction:

Improvehermetic barrier integrityVSAvoidoptical alignment precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent segments the sealing function into hermetic sealing (provided by the sheath bonding to substrate) and optical sealing (provided by the sheath surrounding the fiber array). This segmentation eliminates epoxy from the optical sealing function, preventing epoxy shrinkage-induced optical aberrations while maintaining hermetic barrier integrity.

Inventive Principle:

Principle #1Segmentation

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

The solution enhances the lifetime of welded joints, improves vibrational performance, and ensures hermetic sealing, enabling the package to withstand extreme temperature variations and meet stringent testing standards by reducing static fatigue and epoxy shrinkage effects.

Implementation Method 1

utilizing a CTE-matched glass sheath to prevent expansion mismatch

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

using epoxy only at spatially separated ends to bond the sheath to the substrate and fibers

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Implementation Method 3

Each optical fiber of the plurality of optical fibers is bonded to the substrate

Methodology Applied

Scientific EffectWelding: Welding

Data Source

PatentUS20260079305A1Method and system for packaging fiber arrays

Publication Date: 2026.03.19 RAM PHOTONICS INTERCONNECTS LLC

AI summary

A sealed fiber array package includes a substrate and a fiber array including a plurality of optical fibers. Each optical fiber of the plurality of optical fibers is bonded to the substrate. The sealed fiber array package also includes a sheath at least partially surrounding the fiber array. The sheath has a first end abutting the substrate and a second end distal from the substrate. The sealed fiber array package further includes a first seal disposed at the first end of the sheath and a second seal disposed at the second end of the sheath.