Abstract
The droplet formation of Newtonian fluids and suspensions modified by spherical, non-colloidal particles has attracted much interest in practical and theoretical research. For the present study, a jetting technique was used which accelerates a geometrically defined plunger by a piezoelectric actuator. Changing rheological properties of materials and extending deformation rates towards nonlinear viscoelastic regimes created the requirement to extend dosage impulses towards larger magnitudes. To mimic the rheological characteristics of nonconductive adhesives we modified Newtonian epoxy resins by thixotropic additives and micro-scale glass spheres. Rheological analysis at steady shear and oscillatory shear ensured a differentiation between material and process-related factors. Evaluation of high-speed images allowed the investigation of drop dynamics and highlighted the dispense impulse reduction by material-specific dampening properties.
Highlights
The progressive evolution of micro-systems technology and its transition into consumer products requires continuous miniaturization of electronic components
The change in shear flow behavior of the neat and modified epoxy resins is documented by shear
The change in shear flow behavior of the neat and modified epoxy resins is documented by shear rate sweeps, as shown in Figures 4 and 5
Summary
The progressive evolution of micro-systems technology and its transition into consumer products requires continuous miniaturization of electronic components. The first step in the development of chip interconnection technology for advanced applications is the combination of electronic and optoelectronic devices for which suitable support structures are essential For this strategic aim, jetting with piezo-controlled dosing valves is a technology with high potential due to its adaptability and flexibility. General requirements for dispensing small quantities of fluids by jetting are high spatial resolution and short process times. To fulfill these requirements, it is necessary to improve the understanding of drop formation pinch-off and thread movement for fluids with complex rheological behavior [3]. The break-up depended critically on the fluid properties as well as on the type of shockwave applied
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