Lead-free Piezo Printhead Using Thinned BNKT Material
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Solution Overview
Problem
Current piezoelectric ink-jet printheads face challenges in manufacturing smaller actuator sizes and thicknesses, and rely on lead-containing materials that are not environmentally friendly, making it difficult to produce high-resolution prints with lead-free alternatives that are fragile and costly to produce.
Innovation Solution
A lead-free piezoelectric ink-jet printhead system using bismuth sodium potassium titanate (BNKT) material, which is bonded to a diaphragm and thinned to a suitable thickness, with electrode plating on both sides and diced into individual actuators, allowing for efficient ink ejection without the need for traditional MEMS-based fabrication processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free piezoelectric materials (BNKT) are used to replace traditional PZT materials, then environmental compatibility is improved, but the material becomes too thin and fragile to be manufactured and handled in a free-standing state
Solution Approach 1:
A carrier substrate is introduced as an intermediary to support the thin BNKT piezoelectric material during manufacturing and handling. The substrate provides mechanical strength and stability, allowing the fragile thin material to be processed and bonded without damage. After bonding to the diaphragm assembly, the substrate can be removed, leaving the thin piezoelectric layer securely in place.
Solution Approach 2:
The BNKT piezoelectric material is thinned to the required thickness and prepared for bonding before being attached to the diaphragm assembly. This preliminary preparation includes reducing the material to final thickness specifications and positioning it on the carrier substrate, ensuring it is ready for immediate bonding without requiring post-assembly thinning or adjustment.
2Use of energy by moving object
If the piezoelectric material is thinned to achieve high electric fields at low voltage, then operating voltage is reduced, but the material becomes too fragile to handle and manufacture
Solution Approach 1:
The carrier substrate serves as a protective intermediary that enables the use of extremely thin piezoelectric material. By providing mechanical support during manufacturing and handling, the substrate allows the material to be thinned to the point where high electric fields can be achieved at low operating voltages (less than 100 to 120 volts peak-to-peak) without compromising manufacturability.
Solution Approach 2:
The thickness parameter of the piezoelectric material is changed to optimize electrical performance. By reducing thickness to specific ranges, the material achieves the necessary electric field strength at low operating voltages while maintaining compatibility with standard printhead manufacturing processes through the use of carrier substrates.
3Manufacturing precision
If microelectronic fabrication methods are used to control actuator dimensions, then manufacturing precision is improved, but production cost and capital investment increase
Solution Approach 1:
Instead of using complex microelectronic fabrication methods to create each actuator individually, the invention inverts the approach by using standard semiconductor-grade thinning and dicing processes on bulk piezoelectric material. This allows precision actuator dimensions to be achieved through simple mechanical cutting and grinding operations that are already well-established in the industry, avoiding the need for expensive cleanroom facilities and complex fabrication tooling.
Solution Approach 2:
The bulk piezoelectric material is segmented into individual actuator elements through dicing after being thinned to the required thickness. This segmentation approach allows precise control of actuator dimensions by controlling the dicing parameters and thickness uniformity, while maintaining simplicity in the overall manufacturing process and avoiding the need for complex individual actuator fabrication.
4Manufacturing precision
If the density of actuators and nozzles is increased to improve printing resolution, then print resolution is improved, but actuator sizes and thicknesses must be decreased
Solution Approach 1:
The physical parameters of the piezoelectric material (thickness and lateral dimensions) are changed to enable higher actuator density. By reducing material thickness and utilizing standard thinning processes, smaller actuator sizes can be achieved that maintain structural integrity, allowing increased actuator and nozzle density for higher printing resolution without requiring complex design modifications.
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 enables the production of high-resolution prints using lead-free materials, reducing manufacturing costs and environmental impact while maintaining the performance of traditional piezoelectric printheads.
Implementation Method 1
When a voltage is applied across one of the actuators, the actuator bends or deflects, causing the diaphragm to flex, which may either fill the body chamber with ink or eject a quantity of ink from the chamber through a nozzle
Implementation Method 2
The piezoelectric material is plated with a first electrode material on a first side prior to bonding; plating the piezoelectric material on a second side with a second electrode material
Data Source
AI summary
An apparatus for a lead-free piezoelectric ink-jet printhead is disclosed. Piezoelectric printheads, while more expensive are favored because they use a wider variety of inks. The piezoelectric printhead includes a diaphragm, a plurality of piezoelectric actuators comprising a lead-free piezoelectric material, at least one nozzle, at least one ink chamber, a top electrode, and a drive circuit. The deflection of the diaphragm on the body chamber contributes to a pressure pulse that is used to eject a drop of liquid from the nozzle. According to an exemplary embodiment, a lead-free piezoelectric printhead operated at smaller thicknesses and significantly higher electric fields is disclosed, along with methods of making such printheads.