Plasma Bonded Orifice Plate for Corrosion-Resistant Printheads

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Solution Overview

Problem

Conventional thermal inkjet printheads face issues with corrosion susceptibility of metal and polyimide orifice plates and organic barrier layers, which limit ink chemistry options and require precise alignment and adhesive bonding, leading to potential inaccuracies in ink drop trajectory.

Innovation Solution

The use of direct contact bonding between an orifice sub-structure and an ejector element sub-structure using low-temperature plasma activated bonding techniques, eliminating the need for organic barrier layers and allowing for a robust, inert firing chamber structure with wide ink compatibility, and a method for wafer-level attachment of pre-fabricated dielectric orifice sub-structure and nearly fully processed thermal ejector element sub-structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal or polyimide orifice plates are used, then structural integrity is improved, but corrosion susceptibility increases limiting ink chemistry options

Engineering Contradiction:

Improvestructural integrityVSAvoidink chemistry options

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent employs a composite structure consisting of a dielectric orifice plate bonded to a substrate containing firing chambers. The dielectric material provides both structural integrity and chemical inertness, allowing the system to maintain strength while being compatible with a wide range of ink chemistries including aggressive solvents that would corrode metal or degrade polyimide.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If conventional adhesive bonding is used to attach orifice plate, then attachment is achieved, but alignment precision and ink drop trajectory control deteriorate

Engineering Contradiction:

Improveattachment processVSAvoidalignment precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent eliminates the adhesive layer entirely by using direct contact bonding between the dielectric orifice plate and the substrate. This removal of the intermediate adhesive layer eliminates the source of alignment errors and trajectory control issues, while the direct bonding process maintains ease of manufacture through wafer-level processing.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical adhesive bonding system with a direct contact bonding system that uses plasma activation and thermal processing. This substitution eliminates the need for adhesives and achieves superior alignment precision through direct surface contact and bonding at the wafer level.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Area of stationary object

If thick dielectric layers are deposited for orifice plate fabrication, then coverage is improved, but built-in stresses and deposition temperature increase

Engineering Contradiction:

Improvecoverage areaVSAvoidbuilt-in stresses

Core Design Contradiction:

Area of stationary objectVSStress or pressure

Solution Approach 1:

The patent modifies the deposition parameters by using plasma-enhanced chemical vapor deposition (PECVD) to deposit the dielectric layer at lower temperatures compared to conventional CVD. This parameter change reduces the deposition temperature while maintaining adequate coverage, and the resulting film has reduced built-in stresses due to the lower deposition conditions.

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 approach enhances the structural integrity and alignment precision of printheads, reducing the risk of corrosion and improving ink drop trajectory control, enabling the use of aggressive solvents and expanding ink chemistry options while maintaining low-temperature and low-stress processing.

Implementation Method 1

direct contact bonding between an orifice sub-structure and an ejector element sub-structure using low-temperature plasma activated bonding techniques

Methodology Applied

Scientific EffectPlasma activated bonding: Plasma

Data Source

PatentUS8109607B2Fluid ejector structure and fabrication method

Publication Date: 2012.02.07 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

In one embodiment, a fluid ejector structure includes an orifice sub-structure and an ejector element sub-structure direct contact bonded together along a direct contact bonding interface. The orifice sub-structure has a plurality of orifices therein. Each orifice is positioned adjacent to a corresponding one of a plurality of fluid ejection elements on the ejector element sub-structure.