Photoimageable Dry Film Adhesion for Fluidic Ejection Heads
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Solution Overview
Problem
The existing photoresist dry film formulations for fluidic ejection heads suffer from significant loss of adhesion enhancer during the drying process, leading to poor adhesion between the fluid flow layer and the substrate or nozzle plate, which affects the performance and reliability of the fluidic ejection devices.
Innovation Solution
A method using a photoimageable dry film formulation comprising a multi-functional epoxy compound, a photoacid generator, a silane oligomer adhesion enhancer, and a non-photoreactive solvent, where the silane oligomer adhesion enhancer is an alkoxysilane compound like gamma-glycidoxypropyltrimethoxysilane, is applied to a release film, dried, and then laminated to a semiconductor substrate to form a thick film layer with improved adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional photoresist dry film formulation is used, then the formulation can be applied and dried, but significant loss of adhesion enhancer occurs during drying, leading to poor adhesion
Solution Approach 1:
The patent changes the chemical parameters of the adhesion enhancer by using a silane oligomer with specific molecular weight (500-5000 Daltons) and structure (alkoxysilane with epoxide or carboxyl functional groups). This parameter optimization allows the adhesion enhancer to maintain stability during drying while achieving strong adhesion between layers.
Solution Approach 2:
The patent creates a composite photoresist formulation combining multiple components: photoactive compound (5-30 wt%), multi-functional epoxy compound (30-60 wt%), silane oligomer adhesion enhancer (0.5-5 wt%), and solvent (5-30 wt%). This composite structure ensures proper distribution and retention of the adhesion enhancer throughout the drying process, preventing loss and ensuring reliable adhesion.
2Reliability
If the adhesion enhancer concentration is increased to compensate for loss, then adhesion may improve, but the formulation becomes more complex and costly
Solution Approach 1:
Instead of simply increasing adhesion enhancer concentration, the patent optimizes the molecular parameters of the silane oligomer (molecular weight 500-5000 Daltons, specific functional groups) to achieve maximum adhesion efficiency at low concentrations (0.5-5 wt%), thereby avoiding formulation complexity while maintaining strong adhesion.
Solution Approach 2:
The silane oligomer adhesion enhancer is designed to self-distribute uniformly throughout the photoresist formulation during application and drying, eliminating the need for complex processing steps or additional adhesion promotion treatments. The formulation self-optimizes adhesion through the inherent properties of the silane oligomer.
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 improved formulation enhances the adhesion between the semiconductor substrate and the fluid flow layer and between the fluid flow layer and the nozzle plate, resulting in more reliable and efficient fluid ejection performance by minimizing delamination when exposed to fluids.
Implementation Method 1
a photoacid generator, wherein the photoacid generator is triphenylsulfonium triflate
Implementation Method 2
a silane oligomer adhesion enhancer, wherein the silane oligomer adhesion enhancer is an alkoxysilane oligomer compound
Data Source
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AI summary
An improved photoimageable dry film formulation, a fluidic ejection head containing a thick film layer derived from the improved photoimageable dry film formulation, and a method for making a fluidic ejection head. The improved photoimageable dry film formulation includes a multifunctional epoxy compound, a photoinitiator capable of generating a cation, a non-photoreactive solvent, and from about 0.5 to about 5 % by weight a silane oligomer adhesion enhancer based on a total weight of the photoimageable dry film formulation before drying.