Fluidic Die Adhesion Layer Design for Optical Reflection and Fluid Ingress
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Solution Overview
Problem
The existing fluidic dies face issues with fluid ingress causing corrosion of electrical structures, optical reflections leading to deformities in the fluidic barrier layer, and reduced print quality due to increased pitch between fluid chambers, especially when using SiC or SiN layers in the die surface optimization (DSO) layer.
Innovation Solution
A dual-layer DSO approach is implemented, where a first portion covering electrical structures includes both a dielectric (SiN) and adhesion (SiC) layers, and a second portion in fluidic regions includes only the adhesion layer, which is anti-reflective, aiding in denser arrangements of fluid chambers and protecting electrical structures from fluid intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a SiC or SiN layer is used in the die surface optimization (DSO) layer, then adhesion between metallic layers and fluidic barrier layer is improved, but optical reflections occur leading to deformities in the fluidic barrier layer
Solution Approach 1:
The DSO layer is segmented into two distinct portions: a first portion containing both dielectric and adhesion layers for electrical structures, and a second portion containing only the adhesion layer for fluidic regions. This segmentation allows the adhesion layer to provide anti-reflective properties in fluidic regions while the dielectric layer provides protection in electrical regions.
Solution Approach 2:
Different portions of the DSO layer are given different compositions tailored to local requirements: the first portion over electrical structures includes both dielectric and adhesion layers for comprehensive protection, while the second portion in fluidic regions includes only the adhesion layer to provide anti-reflective properties without the harmful effects of dielectric materials exposed to fluid.
2Ease of manufacture
If the pitch between fluid chambers is increased, then manufacturing complexity is reduced, but print quality deteriorates
Solution Approach 1:
The adhesion layer, which has anti-reflective properties, is utilized to counteract optical reflections that would otherwise cause deformities in the fluidic barrier layer. This converts a potentially harmful optical effect into a beneficial feature that enables tighter pitch between fluid chambers, thereby improving print quality while maintaining manufacturing feasibility.
3Device complexity
If the DSO layer structure is simplified, then device complexity is reduced, but protection against fluid ingress is compromised
Solution Approach 1:
The DSO layer is divided into two portions with different structures: the first portion over electrical structures includes both dielectric and adhesion layers for comprehensive protection against fluid ingress, while the second portion in fluidic regions includes only the adhesion layer. This segmentation provides necessary protection where needed while reducing complexity in regions where full protection is not required.
Solution Approach 2:
The DSO layer structure is locally optimized: areas requiring fluid protection (electrical structures) receive the full two-layer structure, while areas in direct contact with fluid (fluidic regions) receive only the adhesion layer, achieving appropriate protection levels without unnecessary complexity.
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 solution effectively prevents fluid ingress and corrosion, reduces optical reflections, and allows for a denser arrangement of fluid chambers, enhancing print quality by maintaining a smaller pitch between fluid chambers while protecting electrical structures.
Implementation Method 1
the adhesion layer, which is anti-reflective, aiding in denser arrangements of fluid chambers
Implementation Method 2
a first portion covering electrical structures includes both a dielectric (SiN) and adhesion (SiC) layers
Implementation Method 3
a second portion in fluidic regions includes only the adhesion layer
Data Source
AI summary
In some examples, a fluidic die includes a substrate, a fluidic region comprising fluid chambers formed in a fluidic barrier layer supported by the substrate, fluidic actuators associated with the fluid chambers, electrical structures positioned away from the fluidic region, a metallic layer over the fluidic actuators, and an adherent barrier layer to adhere the metallic layer to the fluidic barrier layer. The adherent barrier layer includes a first adherent barrier layer portion comprising a dielectric layer and an adhesion layer, and a second adherent barrier layer portion comprising the adhesion layer and without the dielectric layer, the first adherent barrier layer portion formed over the electrical structures, and the second adherent barrier layer portion formed in the fluidic region, the adhesion layer of the second adherent barrier layer portion protruding into the fluid chambers.