Jet Dispensing Technologies in Microelectronic Packaging

Jet dispensing has emerged as a pivotal non-contact technique for depositing minute volumes of adhesives, solder pastes and encapsulants in the assembly of microelectronic devices. By propelling fluid droplets through a nozzle orifice with precise control over volume, velocity and placement, jet dispensers accommodate the increasing demands for miniaturisation, high throughput and heterogeneous material integration. Core components include an actuator to drive a needle or membrane, a fluid reservoir, and a nozzle whose geometry governs droplet formation. Actuation mechanisms range from piezoelectric stacks and magnetostrictive elements to pneumatic pulses, each offering distinct advantages in response speed, blocking force and displacement amplification. Progress in computational modelling has elucidated multiphase flow, rheological influences and droplet break-up dynamics, while experimental investigations optimise parameters such as drive pressure, needle stroke and orifice size. The resulting capabilities support fine-pitch solder paste deposition, underfill application around flip-chip assemblies and precisely patterned adhesive bonds, underpinning advances in high-density interconnects and three-dimensional packaging architectures.

Research from Nature Portfolio

Innovative work has applied giant-magnetostrictive materials in jet dispensers coupled with a lever-hinge amplification mechanism to enhance jetting frequency and needle velocity. A comprehensive system model integrating circuit, electro-magneto-displacement and fluid-solid coupling elements demonstrated frequencies approaching 250 Hz and adjustable dot sizes via controlled fill pressure or current amplitude. Separately, high-resolution measurement of needle motion using accelerometers has clarified the interplay between travel distance, bounce-back and droplet ejection. By visualising jetting behaviour, an optimal range of needle travel was identified that yields single droplets per trigger, leading to a systematic parameter-selection framework for reliable and repeatable jet dispensing.

Research from all publishers

Numerical and experimental studies have characterised the five-stage cycle of needle-type micro-liquid jetting dispensers, analysing backflow, growth, extension, breakage and separation. These investigations revealed that higher driving pressures favour viscous fluids, while nozzle diameter and needle stroke must be balanced to avoid satellite droplets or flow-stream instabilities. Complementary work on droplet volume control employed multiphysics simulations and test beds to map the effects of air pressure, nozzle dimensions, needle displacement and fluid viscosity, establishing practical parameter ranges for producing consistent droplet sizes across different adhesive formulations. Further research on needle geometry showed that adding a side cap structure elevated nozzle-cavity pressure by more than twofold and increased jet velocity, with optimal conic angles and clearances identified for stable microscale dispensing. Collectively, these studies inform the design of dispensers that deliver precise, uniform droplets in high-density packaging processes.

Jet Dispensing Technologies in Microelectronic Packaging publication trend

The graph below shows the total number of articles in jet dispensing technologies in microelectronic packaging across all publications each year (not limited to Nature Index journals).

Technical terms

Jet dispensing: A non-contact method for ejecting small fluid volumes through a nozzle to achieve precise droplet placement in microelectronics assembly.

Piezoelectric actuator: A solid-state device that converts electrical signals into mechanical displacement, used to drive the dispenser needle or membrane.

Needle-collision mechanism: A dispensing approach where a driven needle impacts a nozzle seat to initiate droplet ejection and control volume.

Magnetostrictive material: A ferromagnetic alloy that changes shape under a magnetic field, providing rapid actuation and high blocking force.

Rheological properties: Characteristics of fluid viscosity and elasticity that influence droplet formation, breakup and surface adhesion.

Satellite droplets: Undesired secondary droplets that form alongside the primary jet, potentially leading to placement errors and contamination.

References

1. The principle and physical models of novel jetting dispenser with giant magnetostrictive and a magnifier. Scientific Reports (2015).
2. Simulation and Experiment on Droplet Formation and Separation for Needle-Type Micro-Liquid Jetting Dispenser. Micromachines (2018).
3. Simulation and Experiment on Droplet Volume for the Needle-Type Piezoelectric Jetting Dispenser. Micromachines (2019).
4. Effect of Enhanced Squeezing Needle Structure on the Jetting Performance of a Piezostack-Driven Dispenser. Micromachines (2019).
5. How to manipulate droplet jetting from needle type jet dispensers. Scientific Reports (2019).