MEMS Inkjet Printhead Polymerized Siloxane Hydrophobic Coating
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Solution Overview
Problem
Inkjet printheads face challenges in fabricating a hydrophobic ink ejection face while maintaining hydrophilic nozzle chambers, as existing MEMS techniques often remove hydrophobic materials during the ashing process, leading to undesirable hydrophobization of nozzle chamber walls and ink flooding issues.
Innovation Solution
A printhead fabrication process involving the use of hydrophobic polymeric materials like polymerized siloxanes and fluorinated polyolefins, which are resistant to ashing and form a passivating surface oxide in oxygen plasma, ensuring a hydrophobic ink ejection face without compromising nozzle chamber hydrophilicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MEMS fabrication techniques are used, then manufacturing process simplicity is maintained, but the ink ejection face becomes hydrophilic due to ashing process, causing ink flooding
Solution Approach 1:
The patent applies preliminary action by depositing the hydrophobic polymer coating on the ink ejection face before the ashing process. This pre-coating ensures that the hydrophobic property is established prior to manufacturing steps that would otherwise remove it, allowing the ashing process to proceed without compromising the final hydrophobicity of the ink ejection face
Solution Approach 2:
The patent changes the material parameter by using ash-resistant hydrophobic polymer materials (such as fluorinated polymers or siloxane-based polymers) that maintain their hydrophobic properties during the ashing process. This parameter change allows the coating to withstand the manufacturing process without degrading its functional properties
2Reliability
If hydrophobic coating is applied to the ink ejection face, then ink flooding is prevented, but the nozzle chamber walls become hydrophobized, compromising ink supply
Solution Approach 1:
The patent applies local quality by selectively coating only the ink ejection face with hydrophobic material while leaving the nozzle chamber walls uncoated or with different surface properties. This is achieved through precise coating process control, masking techniques, or selective deposition methods that apply the hydrophobic coating only to specific regions where it is needed, maintaining hydrophilic properties in the nozzle chambers for proper ink supply
3Ease of manufacture
If ashing process is used to remove photoresist, then manufacturing simplicity is maintained, but hydrophobic materials are removed, leading to hydrophobization of nozzle chambers
Solution Approach 1:
The patent extracts the problematic step of using ashing to remove photoresist from the nozzle chamber areas. This is achieved by using alternative photoresist removal methods such as chemical etching or mechanical removal that do not involve high-temperature oxygen plasma ashing, thereby preserving the hydrophilic nature of the nozzle chamber walls while still achieving complete photoresist removal
Solution Approach 2:
The patent introduces an intermediary protective layer or masking material that protects the nozzle chamber walls during the ashing process. This intermediary layer allows the ashing process to proceed efficiently for photoresist removal while preventing the hydrophobizing effect from reaching the nozzle chamber surfaces, thus maintaining their hydrophilic properties
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 process results in improved surface characteristics with a hydrophobic ink ejection face and hydrophilic nozzle chambers, minimizing ink flooding and maintaining effective ink pressure, thus enhancing printhead performance and reliability.
Implementation Method 1
form a passivating surface oxide in oxygen plasma
Implementation Method 2
hydrophobic polymeric materials like polymerized siloxanes and fluorinated polyolefins, which are resistant to ashing
Data Source
AI summary
A MEMS integrated circuit comprises: a silicon substrate having a passivated CMOS layer, a MEMS layer disposed on the passivated CMOS layer, and a polymer layer disposed on the MEMS layer. The CMOS layer comprises drive circuitry for actuating actuator devices in the MEMS layer and the polymer layer comprises a polymerized siloxane.