Irving Rodriguez | Essemtec: How does "jetting on the fly" impact material selection and process control?

Why does the viscosity of your jetting material drop by a factor of 1000 during ejection?

Fluid rheology is the cornerstone of successful high-speed jetting in microelectronics and display packaging. When a material containing suspended particles is subjected to high shear rates inside a jetting chamber, it undergoes dramatic shear thinning, reducing its viscosity by up to three orders of magnitude. This non-Newtonian transition is crucial to control, as temperature fluctuations of just ten degrees Celsius can also significantly alter the baseline viscosity.

As particle concentration increases—common in conductive adhesives and structural epoxies—the fluid behavior shifts from Newtonian to highly non-Newtonian. Under extreme shear rates, these concentrated suspensions can transition from shear thinning to shear thickening. This chaotic particle behavior increases viscosity abruptly, potentially clogging the nozzle or causing unstable jetting.

Understanding these complex rheological transformations is essential when selecting the appropriate jetting technology and material formulation. Optimizing parameters like chamber temperature and drive energy prevents processing failures and ensures consistent droplet deposition for fine-pitch electronics.

In this short video, you can learn:
* How shear rates reduce material viscosity by a factor of 1,000 during the jetting process.
* The transition of suspension fluids from Newtonian behavior to shear thinning and shear thickening.
* The critical impact of minor temperature variations on the rheological stability of structural glues.

📋 **Clip Abstract** This clip explains the complex rheological behavior of particulate fluids during high-speed jetting processes. It highlights the transition from shear-thinning to shear-thickening under high shear rates and the critical role of temperature and particle concentration on fluid viscosity.

What are the real-world tolerances and throughput limits for high-speed micro-dispensing systems?

Implementing micro-jetting and pick-and-place systems in high-volume manufacturing requires a clear understanding of practical tolerances and throughput constraints. In precision dispensing, droplet volume tolerance typically lands within a plus or minus twenty percent margin of the target value. This variance is highly dependent on substrate conditions, such as surface energy, which influences the final spread and contact angle of the dot.

Valve selection in modern dispensing equipment is not based on a single variable but on a complex matrix of viscosity, jetting speed, and desired dot sizes. Achieving high-yield assembly requires systems to dynamically manage these parameters while maintaining impressive throughputs. Typical production speeds reach twelve to sixteen thousand components per hour for pick-and-place, and up to fifty thousand dots per hour for specialized dispensing.

Fine-pitch components place strict limits on the mechanical capabilities of the assembly machine. For surface-mount devices (SMD) and micro-scale components, modern all-in-one systems can reliably achieve minimum pitch sizes down to 0.3 millimeters, ensuring high-density packaging capability.

In this short video, you can learn:
* The standard volume tolerances for high-speed micro-dispensing and the impact of substrate surface energy.
* How viscosity, velocity, and dot size are used to select and configure jetting valves.
* The throughput metrics and minimum pitch limits achievable in integrated pick-and-place and dispensing systems.

📋 **Clip Abstract** This Q&A segment outlines the performance benchmarks of Essemtec's dispensing systems, highlighting a plus or minus twenty percent droplet volume tolerance. It details the operational speeds for pick-and-place and dispensing, alongside the 0.3 mm minimum pitch capability for fine-pitch SMT assembly.

How do fluid dynamics and jetting energy interact to dictate the morphology of micro-dispensed conductive and dielectric dots in printed electronics?

In high-precision additive manufacturing, jetting morphology is highly sensitive to the interplay between fluid rheology and ejection energy. When dispensing functional inks or adhesives, operating at a lower medium temperature increases fluid viscosity. Combining this high-viscosity state with low jetting speed—where the kinetic energy of the flying dot is minimal—results in a "tower dot" morphology, characterized by high-aspect-ratio vertical stacking.

Conversely, transitioning to a high-velocity, high-energy ejection system coupled with a lower-viscosity medium yields a "donut dot" morphology. This ring-like structure is typically achieved via a single-shot deposition, whereas tower structures often require multiple superimposed shots. Controlling these distinct fluid behaviors is critical for maintaining structural integrity and electrical performance in printed components.

Optimizing throughput introduces a trade-off between dot volume and process speed. Utilizing a physical setup optimized for micro-dots to deposit larger volumes requires accumulating numerous single dots, which significantly penalizes cycle times. Achieving the ideal equilibrium between dot design, fluidic properties, and dispensing speed remains a highly customized engineering challenge unique to each application.

In this short video, you can learn:
* How the combination of low jetting speed and high viscosity produces tower dot morphologies.
* The physical mechanisms that generate donut dot structures using high-energy jetting and low-viscosity media.
* The cycle-time trade-offs involved when scaling up dot volume using a single physical dispensing setup.

📋 **Clip Abstract** The speaker compares "tower dot" and "donut dot" dispensing morphologies, explaining how they are produced by different combinations of jetting speed, ejection energy, and medium viscosity. He also discusses the throughput challenges of using a small-dot dispensing setup to deposit larger volumes, emphasizing the need to balance dot design and process speed.

🎤 Speaker: Irving Rodriguez
🏢 Company: Essemtec
📅 Event: Printed Electronics Innovation Day 2024
📍 Location: TechBlick | Online Platform

🌐 Learn more at the next TechBlick event: https://www.techblick.com