Substrate Joined Body with Carbon-Silicon Buffer Film
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Solution Overview
Problem
The existing methods for forming a protective film on a substrate joined body, particularly with an organic film, face challenges such as cracking and peeling due to stress from temperature and pressure changes, leading to poor bonding and discharge performance in liquid discharge heads.
Innovation Solution
A substrate joined body is developed with an organic film comprising silicon and carbon, where the carbon to silicon ratio is controlled between 0.0 to 5.0 atomic percentage within 50 nm from the surface, and a protective film with an inorganic element is formed using atomic layer deposition, enhancing adhesive strength and resistance to peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a protective film is formed directly on an organic film (adhesive) to protect the substrate joined body from ink erosion, then the substrate protection is improved, but the protective film develops cracks and peels due to stress from temperature and pressure changes
Solution Approach 1:
A buffer film is introduced as an intermediary layer between the organic film (adhesive) and the protective film. This buffer film absorbs the stress generated by temperature and pressure changes, preventing the protective film from cracking and peeling while maintaining the ink erosion protection function.
Solution Approach 2:
The organic film's composition is modified by controlling the carbon to silicon ratio within 50 nm from the surface to be 0.0 to 5.0 atomic percentage. This parameter change enhances the adhesive strength between the organic film and protective film, preventing peeling under thermal and pressure stress.
2Strength
If the adhesive force between the protective film and organic film is increased to prevent peeling, then the bonding strength is improved, but the protective film becomes more rigid and susceptible to cracking under stress
Solution Approach 1:
The buffer film serves as a stress-absorbing intermediary that decouples the rigid protective film from the organic film, allowing strong bonding without transmitting cracking stress to the protective film.
Solution Approach 2:
A composite structure consisting of the organic film, buffer film, and protective film is created. Each layer has different mechanical properties that complement each other, achieving both strong adhesion and crack resistance through the composite system.
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 suppresses cracking and peeling of the protective film, ensuring robust bonding between substrates and maintaining discharge performance even under ink exposure.
Implementation Method 1
at least one material (protective film 200) selected from the group consisting of tantalum oxide, hafnium oxide and zirconium oxide formed by atomic layer deposition from the inner wall surface over the top of the adhesives 210 to 212
Data Source
AI summary
A substrate joined body including: a first substrate; a second substrate; an organic film that comprises silicon and carbon and joins the first substrate and the second substrate; and a protective film that comprises an inorganic element and is formed over the organic film from at least a part of the surface of the first substrate and at least a part of the surface of the second substrate, wherein the protective film comprises a region in which the ratio of carbon to silicon based on atomic percentage is from 0.0 to 5.0 in a region within 50 nm in a thickness direction from a surface of the organic film on the protective film side, when the surface is measured by X-ray photoelectron spectroscopy.