Ink Jet Printhead Polymerization Inhibitor

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Ink jet printhead manufacturing faces issues with unwanted polymerization residues during photolithographic processes, leading to defects and reduced yields due to radiation reflection on substrates, which are not effectively addressed by existing technologies designed for smaller integrated circuit dimensions.

Innovation Solution

A photolithographic process using a photosensitive mix with a polymerization inhibitor to neutralize acid species generated by radiation reflection, ensuring controlled polymerization in protected areas and preventing unwanted polymerization in areas exposed to reflected radiation, thereby minimizing residues and improving structural layer quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If photolithographic process is used to manufacture ink jet printhead structures, then tridimensional structures can be formed, but unwanted polymerization residues occur due to radiation reflection on substrate

Engineering Contradiction:

Improvegeometric regularity of structuresVSAvoidunwanted polymerization residues

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful reflected radiation into a beneficial effect by adding a polymerization inhibitor that specifically counteracts the acid species generated by reflected radiation in protected areas, while allowing polymerization to proceed in exposed areas. This transforms the harmful reflection into a controllable process parameter.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces a polymerization inhibitor as an intermediary substance that mediates between the reflected radiation and the photosensitive material. The inhibitor selectively neutralizes acid species in protected areas without preventing polymerization in exposed areas, thus controlling the harmful effect of reflected radiation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If existing photolithographic technologies are used, then manufacturing process can be maintained, but yield is reduced due to polymerization defects

Engineering Contradiction:

Improveproduction yieldVSAvoidstructural layer quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the photosensitive material by incorporating a polymerization inhibitor with specific properties (basic compound with pKa between 5-11). This parameter change allows the system to tolerate reflected radiation without producing defects, thereby improving both yield and reliability.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If radiation reflection is present during photopolymerization, then energy is conserved, but geometric irregularities increase in produced structures

Engineering Contradiction:

Improveradiation energy reflectionVSAvoidgeometric regularity

Core Design Contradiction:

Loss of energyVSShape

Solution Approach 1:

The patent applies preliminary anti-action by incorporating the polymerization inhibitor into the photosensitive material before exposure. The inhibitor is pre-positioned to counteract the harmful effects of reflected radiation before they can cause geometric irregularities, thus maintaining shape accuracy while preserving energy reflection.

Inventive Principle:

Principle #9Preliminary anti-action

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 method effectively produces tridimensional structures for ink jet printheads with reduced geometric irregularities and increased yield by preventing unwanted polymerization, resulting in improved electrical contact and reduced production costs.

Implementation Method 1

irradiating with ultraviolet radiation (UV) to generate acid species suitable for promoting polymerization of the solution in the areas not protected by the masking

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

neutralizing the unwanted acid species by means of the inhibitor basic compound

Methodology Applied

Scientific EffectNeutralization reaction: Redox Reactions

Implementation Method 3

a fraction of the radiation is reflected by the reflecting part on the inside of the areas protected by the masking and generates unwanted acid species

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS8263293B2Tridimensional structures for an ink jet printhead and relevant manufacturing process

Publication Date: 2012.09.11 TELECOM ITALIA SPA

AI summary

In a monolithic ink jet printhead, a structural layer is made comprising cavities, obtained from the polymerization of a solution of a monomer, or an oligomer, and a photointiator; during the polymerization by radiation, acid species are unduly generated in zones protected by a mask, due to reflection of the radiation on reflecting surfaces of the support of the sructural layer; these acid species cause undue polymerization of the solution on the inside of the cavities to oppose the formation of these acid species, a polymerzation inhibitor basic compound is used.