I. Abstract of the Paper’s Core Research

This study employs an aerodynamic atomization aerosol‑printing system, using silver‑cluster conductive ink as the printing material. Comprehensive experiments were conducted across a full factorial design, focusing on three key process parameters: sheath‑gas flow rate, atomizing‑gas flow rate, and print‑travel speed. Optical profilometry, electrical characterization, and variance analysis were integrated to quantitatively elucidate the underlying process‑control relationships, enabling the development of a predictive regression model and the establishment of a stable, scalable production window. The key findings are as follows:

A Comprehensive Analysis of the Mechanisms Underlying the Three Key Parameters

The atomization gas flow rate directly determines the total aerosol delivery; higher flow rates result in greater deposition and wider lines. The sheath gas focuses the jet, and increasing its flow can narrow the line width, while excessive flow can break up the droplets, leading to line breaks. Printing speed is inversely related to deposition thickness—higher speeds tend to produce satellite droplet defects. Substrate temperature helps regulate solvent evaporation, further improving edge smoothness.

A quantitative regression prediction model has been successfully constructed.

Response surface analysis was conducted using data from 50 gradient experiments, yielding a linear prediction equation for line width. The adjusted coefficients reveal the relative influence of each parameter in the following order: atomizing gas > sheath gas > printing speed. With a model fit of 76.4%, this approach enables early prediction of target line dimensions, significantly reducing the number of trial prints required.

Three-level quality process window partitioning

Based on line morphology and resistivity stability, three major process windows—high‑quality, low‑quality, and defective—are defined. The optimal operating ranges for the atomization gas (800–1200 sccm) and the sheath gas (80–100 sccm) are specified, within which the lines remain intact and the resistivity is stably maintained at 1.5×10⁻⁶ Ω·cm².

Long-term mass-production stability verification

Under optimal process conditions, continuous printing for 5 hours without interruption yields line-width variation of ≤4% and resistivity variation of ≤3%; pneumatic atomization minimizes nozzle clogging, significantly extending the equipment’s continuous operating time compared to inkjet printing.

Verification of Ink–Substrate Compatibility

The parameter trends under the two substrate systems—low-viscosity silver ink and commercial high-viscosity silver paste, as well as silicon wafers and PI flexible films—are entirely consistent, demonstrating that the optimization logic is universally applicable and can be extended to the development of various conductive inks.

II. Complete Preparation Procedure for Pneumatic Aerosol Electrodes

Ink Preparation: Soluble silver cluster ink (viscosity 10 cPs), compatible with a pneumatic atomization range spanning a wide viscosity spectrum;

Device Configuration: 300 μm ceramic nozzle, with nitrogen as the carrier and sheath gas; a virtual impactor module filters out large droplets to prevent nozzle clogging.

Gradient Variable Experiment: Atomization gas: 400–1200 sccm; sheath gas: 20–100 sccm; printing speed: 1/5/10 mm/s; multiple sets of cross‑experiments.

Substrate Selection Silicon wafers and PI flexible films can be printed with segmented temperature control ranging from 30 to 120°C, as required.

Post-curing: Heat the sample on a hot plate at 150°C for 5 minutes to densify the silver film.

Complete characterization: Edge morphology was observed using an optical microscope, line width and thickness were measured with a 3D profilometer, and the sheet resistance of a 1-cm-wide line was determined using a source‑measure unit.

Statistical Modeling: Analysis of variance combined with response surface methodology was employed to define a stable process window and conduct long-term production validation.

III. Five Core Process Advantages of Pneumatic Aerosol Dispensing

The pneumatic atomization system boasts an exceptionally broad viscosity compatibility range.

Compatible with conductive inks ranging from 1 to 1000 cP; both low-viscosity silver clusters and high-viscosity commercial silver pastes can be stably atomized, overcoming the limitations of ultrasonic aerosol ink technology.

Virtual Impact Structure Anti-Blocking Design

Filters large-sized droplets, ensuring uninterrupted, long‑term printing without nozzle clogging and significantly reducing the frequency of production line downtime for maintenance.

Parameters can be quantified for precise control.

The three key variables exert linear effects on linewidth and resistance, enabling the development of a mathematical prediction model that eliminates the need for iterative trial-and-error and rapidly achieves the desired microelectrode dimensions.

Universal stable molding for both soft and rigid substrates

The parameter‑control principles for silicon‑based rigid wafers and PI‑based flexible substrates are unified, enabling a reusable optimization scheme across both flexible‑display and MEMS production lines.

Long-term mass production with low variability

In the optimal process window, batch‑printing dimensions and resistivity variations are kept within 5%, and the defect rate is significantly lower than that of inkjet and slot‑die coating.

IV. Five Core Technological Innovations of This Study

Innovation 1: A Pneumatic AJP Three-Parameter Quantitative Response Surface Optimization System

A comprehensive statistical model has been established for the relationships among sheath gas flow, atomization gas flow, and printing speed, as well as microelectrode morphology and electrical performance, yielding a regression equation that enables direct calculation of line width.

Innovation: Two-Level Grading Standard for Defining the Production Process Window

Define high‑quality, low‑quality, and defective ranges based on device yield, and provide a standardized operating manual with industry‑standard equipment parameters.

Innovation: An Analysis of the Three-Pneumatic Atomization Anti-Clogging Forming Mechanism

This clarifies the principle by which the virtual impact module filters out large droplets, addressing the core pain points of nozzle clogging and wire breakage in mass production and thereby improving equipment utilization.

Innovation 4: Universal Optimization Logic for Multiple Inks and Substrates

The verification shows that the trends in high- and low-viscosity silver inks are consistent with those of soft and rigid substrate parameters, demonstrating that the optimization method is universally applicable across the industry.

Innovation 5: Evaluation Scheme for Long-Term Continuous Printing Stability

Establish a 5-hour continuous mass-production verification standard, using linewidth and resistivity variation as metrics for assessing yield.

V. Current Industry Challenges and Corresponding Solutions

Challenge 1: Aerosol process optimization relies entirely on manual trial-and-error, with no quantitative predictive tools, resulting in a lengthy R&D cycle.

✅ A regression equation for predicting line width has been established; by inputting gas flow rate and velocity, the line dimensions can be predicted, reducing the need for hundreds of trial samples.

Challenge 2: In mass production, printing often suffers from defects such as material overflow, filament breakage, and short circuits, making it difficult to improve yield.

✅ Defined a standardized, stable process window and optimized the ratio of shielding gas to atomization gas, significantly reducing morphological defects.

Challenge 3: Prolonged printing causes nozzle clogging, leading to frequent line shutdowns for maintenance.

✅ The pneumatic system, combined with a virtual impact‑based filtration structure, effectively removes large droplets, ensuring 5 consecutive hours of uninterrupted operation and significantly boosting equipment availability.

Challenge 4: Flexible and rigid substrates have significantly different process parameters, requiring repeated debugging on two separate production lines.

✅ The same optimization logic is applicable across both silicon and PI substrates, with consistent parameter‑variation patterns, enabling direct reuse across production lines.

Challenge 5: Significant viscosity differences among various conductive inks make equipment adaptation and debugging cumbersome.

✅ Pneumatic atomization is compatible with an ultra-wide viscosity range, enabling the printing of both high- and low-viscosity silver pastes without any equipment modifications.

VI. Future Diversified Industrial Application Scenarios

1 Flexible Display Pixel Microelectrode Array

High-uniformity micron-scale conductive traces, with low‑variation process compatibility for mass‑production OLED and Mini LED lines.

2 MEMS inertial/pressure sensing interdigital electrodes

High-precision, low-resistance micro-patterns for the mass production of automotive and consumer‑electronics micro‑sensor chips.

3 Flexible Wearable Physiological Sensing Electrodes

PI-based stable conductive circuits enable the mass production of sweat‑based electrocardiogram monitoring patches.

4 mm-Wave RF Micro-Interconnects

Narrow-edge, low-loss conductive microstrip; low-cost additive manufacturing of 5G/6G RF modules.

5 Rapid Development Platform for Laboratory Ink Formulation

Standardized parameter optimization workflow, enabling rapid formulation and batch validation of various metal‑based composite inks.

Image and Text Guide

• The system is divided into two major modules: Pneumatic atomizer (Aerosolization generates 1–5 μm microdroplets) and Deposition head (The sheath gas focuses the aerosol into a narrow beam and prevents clogging), while the intermediate virtual impactor (VI) removes excess gas and increases aerosol density.
• Key flow relationship: Q _Push   = Q _Atomizer   + Q _VISheath   − Q _VIExhaust ;Q _{Total Nozzle}   = Q _Push   + Q _Sheath 。
• This study employs three primary parameters: sheath gas flow rate, nebulizer flow rate, and delivery velocity (using a 300-μm ceramic nozzle with N₂ as both the carrier and sheath gas).

• Increasing the sheath gas flow rate reduces the line width (due to tighter aerosol focusing and a relative decrease in ink jet volume); however, beyond an optimal threshold, line quality deteriorates, and at flow rates exceeding 100 sccm, the lines evolve into ink droplets that render the resistance immeasurable.
• The resistivity of the good printing area is approximately   1.6×10⁻⁶ Ω·cm² , which is essentially independent of the process conditions.
• As the sheath gas focuses, it simultaneously promotes the drying of the aerosol‑surrounding droplets; an incomplete jet can lead to short circuits and a sharp increase in resistivity.

• An increase in the atomizer flow rate leads to a greater amount of atomized ink, which in turn results in wider lines and increased thickness.
• When the flow rate is insufficient, water introduced by the solvent‑replenishment module may create voids or short circuits within the system; when the flow rate is too high and the sheath gas is excessive, the aerosol becomes unstable during drying, rendering resistance measurement impossible.
• The resistivity remains at approximately… during smooth printing.   1.5×10⁻⁶ Ω·cm² , directly influenced by the nebulizer’s flow rate.

• Increasing the deposition speed leads to reduced ink deposition per unit area, resulting in narrower line widths and a greater number of satellite droplets; at excessively high speeds, insufficient aerosol generation causes the resistivity to deviate.
• Due to the viscosity constraints of the ink, the film thickness does not exceed approximately 700 nm, and any excess ink spreads laterally along the line width.
• Within the scope of this experiment, a range of 1–5 mm/s is deemed appropriate; adjusting the deposition rate is the primary means of conveniently controlling the line width.

• An increase in substrate temperature leads to accelerated solvent evaporation and a shortened ink spreading time, resulting in reduced line width and droplet diameter; above 80 °C, the line width decreases significantly.
• At a given ink volume, reducing the line width increases the line thickness, while the cross-sectional area (and thus the volume) remains essentially constant.
• Due to the identical curing process, the resistivity is approximately the same at each temperature (about 1.55×10⁻⁶ Ω·cm²).

• Validation was performed on a PI film using a high-viscosity nano-silver ink (PRELECT TPS 50G2, approximately 50 ± 20 cPs, about five times that of the previous formulation).
• The trends are consistent: as sheath gas flow rate increases, line width decreases; as nebulizer flow rate increases, line width increases; and as delivery speed increases, line width decreases.
• A stable line profile can still be achieved when the sheath gas flow rate exceeds 100 sccm, demonstrating the process’s compatibility with inks of varying viscosities and substrates.

• Factor analysis was conducted on 50 data points (5 lines per condition × 10 measurement points per line): The atomizer flow rate (B) has the greatest impact on line width. , followed by sheath flow rate (A) and distribution velocity (C).
• Regression equation: Line width (µm) = 97.8 − 1.287A + 0.1033B − 5.43C, P ≤ 0.05, adjusted R² = 76.4%.
• The operational window is designed based on the sheath gas–nebulizer flow rate (with the nebulizer operating in the 800–1500 sccm range), and the deposition rate is excluded as it varies inversely with the line width.

• Print one batch every 30 minutes, with 10 lines measured per batch: line width variation at each time point.   ±4% , total deviation after 5 hours of continuous printing   ±5%   Within.
• Resistivity fluctuations across different time periods   ±3% , 5-hour continuous printing variation   ±4%   Within.
• Compared with inkjet and dispensing processes, pneumatic AJP atomizes the ink into fine droplets, significantly reducing the risk of nozzle clogging and offering high industrial‑scale stability.