Protective Coating for Optical Module Bond Pads

Solution Overview

Problem

Optical communications modules face issues with bond wire fragility due to external forces, but existing protection methods are ineffective against electro-chemical reactions and ion migration, leading to corrosion and electrical shorts.

Innovation Solution

A protective coating is applied to encapsulate bond pads on the substrate, increasing dielectric resistance, isolating them from moisture, and preventing ion migration, thereby reducing corrosion and electrical shorts between adjacent bond wires and pads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If bond wires are protected by an enclosure or module body, then protection from external forces is improved, but protection from electro-chemical reactions is not achieved

Engineering Contradiction:

Improveprotection from external forcesVSAvoidprotection from electro-chemical reactions

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

A protective coating is applied over the bond wires and bond pads to provide a barrier against electro-chemical reactions and ion migration. The coating acts as a thin film protective layer that seals the vulnerable electrical connections without requiring a rigid enclosure, thereby addressing the limitation of traditional enclosure-based protection methods.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The protective coating is applied over the bond wires and bond pads to create a composite structure that combines the mechanical strength of the metal bond wires with the chemical resistance of the coating material. This composite approach provides both mechanical protection and protection against electro-chemical degradation.

Inventive Principle:

Principle #40Composite materials

2Strength

If bond wires are encapsulated in dielectric resin, then protection from external forces is improved, but protection from ion migration is not achieved

Engineering Contradiction:

Improveprotection from external forcesVSAvoidprotection from ion migration

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

A protective coating is applied over the bond wires and bond pads to provide a barrier against electro-chemical reactions and ion migration. The coating acts as a thin film protective layer that seals the vulnerable electrical connections without requiring a rigid enclosure, thereby addressing the limitation of traditional enclosure-based protection methods.

Inventive Principle:

Principle #30Flexible shells and thin films

3Productivity

If multiple bond pads are placed close together for dense channel configuration, then channel density is improved, but risk of electrical shorts increases

Engineering Contradiction:

Improvechannel densityVSAvoidrisk of electrical shorts

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A protective coating is applied over the bond wires and bond pads to provide a barrier against electro-chemical reactions and ion migration. The coating acts as a thin film protective layer that seals the vulnerable electrical connections without requiring a rigid enclosure, thereby addressing the limitation of traditional enclosure-based protection methods.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The protective coating serves as an intermediary barrier between adjacent bond pads and bond wires, preventing direct contact that could lead to electrical shorts. This intermediary layer allows for dense packing of electrical connections while maintaining electrical isolation between adjacent conductors.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 protective coating effectively prevents corrosion and electrical shorts, ensuring reliable operation of optical communications modules by enhancing the integrity of bond wires and pads, particularly in densely packed channel configurations.

Implementation Method 1

The protective coating electrically isolates the first and second bond pads disposed on the surface of the substrate from each other

Methodology Applied

Scientific EffectElectrical isolation: Electrical Resistance

Implementation Method 2

The protective coating encapsulates at least the first and second bond pads disposed on the surface of the substrate and extends in between the first and second bond pads

Methodology Applied

Scientific EffectEncapsulation: Physical Containment

Data Source

PatentUS9086553B2Optical communications device having electrical bond pads that are protected by a protective coating, and a method for applying the protective coating

Publication Date: 2015.07.21 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

A protective coating encapsulates bond pads disposed on a substrate of an optical communications module and extends in between the bond pads. The protective coating has characteristics that (1) increase the dielectric resistances between adjacent bond pads on the substrate, (2) protect the bond pads from moisture in the environment, and (3) prevents, or at least reduces, ion migration between adjacent bond pads. In this way, the protective coating prevents, or at least reduces, corrosion growth that can lead to impedance degradation and electrical shorts between adjacent bond pads.