Moisture Protection of Fluid Ejector Actuators
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Solution Overview
Problem
Moisture intrusion into the electrical or actuating components of fluid droplet ejection devices can cause failure due to electrical shorting and degradation of piezoelectric materials, reducing the device's lifetime, and existing polymer moisture barriers have high diffusion rates that hinder effective protection.
Innovation Solution
A thin film with a lower moisture diffusion rate, such as a metal or oxide film, is used in conjunction with a polymer layer to provide both electrical isolation and moisture protection, ensuring the device's functionality and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer moisture barrier is used, then moisture protection is provided, but the high diffusion rate of the polymer reduces protection effectiveness
Solution Approach 1:
The patent applies composite materials by combining a polymer layer with a thin film layer (metal or oxide) having lower moisture diffusion rate. This composite structure leverages the advantages of both materials: the polymer provides baseline protection while the thin film layer significantly reduces moisture diffusion, thereby resolving the contradiction between providing moisture protection and minimizing moisture diffusion rate.
2Reliability
If a thin film with lower moisture diffusion rate is used, then moisture protection is improved, but electrical isolation may be compromised
Solution Approach 1:
The composite structure of polymer layer plus thin film layer (metal or oxide) simultaneously addresses both moisture protection and electrical isolation requirements. The thin film layer provides superior moisture barrier properties while the polymer layer contributes to electrical isolation, ensuring both functions are fulfilled without compromise.
3Duration of action of stationary object
If existing polymer moisture barriers are used, then some protection is provided, but the device lifetime is reduced due to moisture intrusion
Solution Approach 1:
By using a composite moisture barrier structure with polymer and thin film layers, the patent achieves superior moisture protection compared to polymer alone. This enhanced protection directly extends device lifetime by preventing moisture intrusion that would otherwise cause electrical shorting and degradation of piezoelectric materials over time.
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 effectively prevents moisture intrusion, extending the device's lifetime by providing a robust moisture barrier without impairing the actuator's operation, ensuring reliable fluid droplet ejection.
Implementation Method 1
the protective layer having an intrinsic permeability to moisture less than 2.5×10−3 g/m·day
Implementation Method 2
A thin film with a lower moisture diffusion rate, such as a metal or oxide film, is used in conjunction with a polymer layer to provide both electrical isolation and moisture protection
Data Source
AI summary
A fluid ejection apparatus includes a substrate having a plurality of fluid passages for fluid flow and a plurality of nozzles fluidically connected to the fluid passages, a plurality of actuators positioned on top of the substrate to cause fluid in the plurality of fluid passages to be ejected from the plurality of nozzles, and a protective layer formed over at least a portion of the plurality of actuators, the protective layer having an intrinsic permeability to moisture less than 2.5×10−3 g/m·day.