Inkjet Print Head Fabrication Using Sacrificial Substrate Etching
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Solution Overview
Problem
Existing inkjet print head manufacturing methods face challenges in achieving precise control over orifice size, shape, and thermal properties due to the use of metallic or polymeric orifice plates, resulting in less reliable and accurate print heads.
Innovation Solution
A method involving the formation of wafers with sacrificial substrate layers and dielectric layers, where the wafers are joined and aligned to create inkjet orifices and chambers, followed by the removal of the sacrificial substrate to define inkjet print heads, eliminating the need for a pick-and-place process and allowing for more precise control over orifice dimensions and thermal properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a metallic or polymeric orifice plate is used, then the thermal budget control is improved, but the manufacturing precision of orifice dimensions and shape deteriorates
Solution Approach 1:
The patent changes the material parameter of the orifice plate from metallic or polymeric materials to a dielectric material layer formed through semiconductor fabrication processes. This parameter change enables precise control of orifice dimensions (e.g., 10-50 micrometers) and shape through photolithography and etching techniques, while simultaneously providing adequate thermal isolation with thermal conductivity below 1 W/m·K.
Solution Approach 2:
The patent replaces the mechanical pick-and-place assembly process with a wafer-level integration approach where the orifice plate is formed as an integrated dielectric layer on the substrate. This substitution eliminates alignment errors and dimensional variations associated with mechanical assembly, achieving sub-micrometer precision in orifice positioning and dimensions.
2Device complexity
If a pick-and-place technique is used to assemble the orifice plate, then the device complexity is reduced, but the manufacturing precision of orifice alignment and dimensions deteriorates
Solution Approach 1:
The patent merges the orifice plate formation with the substrate fabrication process by forming the dielectric layer containing orifice openings directly on the substrate in the same wafer fabrication line. This integration combines multiple discrete assembly steps into a unified wafer-level process, maintaining simplicity while achieving precise alignment through photolithographic patterning.
Solution Approach 2:
The patent performs preliminary formation of the dielectric layer with precisely defined orifice openings on the substrate before final assembly with the inkjet circuitry. This preliminary action establishes accurate orifice positions and dimensions early in the fabrication process, ensuring alignment precision is built into the structure rather than achieved through post-assembly adjustment.
3Ease of manufacture
If metallic or polymeric orifice plates are used, then the ease of manufacture is improved, but the reliability and accuracy of print heads deteriorates
Solution Approach 1:
The patent changes the fabrication method parameter from mechanical machining or molding of metallic/polymeric plates to semiconductor-style wafer fabrication using photolithography and etching. This enables precise control of orifice dimensions (10-50 micrometers) and shape, directly improving print head accuracy and droplet placement precision while maintaining manufacturability through standardized wafer processing.
Solution Approach 2:
The patent applies local quality control by forming dielectric material layers with specific thermal conductivity properties (below 1 W/m·K) in the orifice plate region, while maintaining different material properties in other regions of the inkjet device. This localized material selection optimizes both thermal isolation for accurate heating and structural integrity for reliable operation.
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 method enables the production of inkjet print heads with improved accuracy and thermal properties, enhancing their reliability and efficiency by avoiding the limitations of metallic or polymeric orifice plates.
Implementation Method 1
Removing the sacrificial substrate layer may include removing the sacrificial substrate layer by at least one of wet etching and reactive ion etching
Implementation Method 2
Removing the sacrificial substrate layer may include removing the sacrificial substrate layer by at least one of wet etching and reactive ion etching
Implementation Method 3
Ink is heated when an electrical pulse energizes a resistive element forming a thermal resistor
Data Source
AI summary
A method of making inkjet print heads may include forming a first wafer including a sacrificial substrate layer, and a first dielectric layer thereon having first openings therein defining inkjet orifices. The method may also include forming a second wafer having inkjet chambers defined thereon, and joining the first and second wafers together so that each inkjet orifice is aligned with a respective inkjet chamber. The method may further include removing the sacrificial substrate layer thereby defining the inkjet print heads.