Hot-melt dispensing in product assembly operations demand process control and accuracy
Hot-melt dispensing is used in mobile device electronics assembly, such as display bonding and component assembly. Typical application goals with hot-melt glues, also known as PUR (PolyUrethane Reactive) materials, require line widths between 200-1000μm and high levels of accuracy and consistency. Hot-melt glues must be dispensed quickly to allow for downstream processing before the material fully cross-links.
PUR materials provide several challenges to automated dispensing operations. The materials are phase changing, meaning they are solid at room temperature and melt at ~100°C. Dispensing systems must safely melt the material, keep it fluid and avoid hardening inside the valve applicator.
In addition to rapid hardening when fluid temperature decreases to ambient, the PUR materials tend to be moisture sensitive. The temperature sensitivity allows the material to be a thermoplastic, reworkable material for a time. However, once the moisture cure sets in, the polymer chains cross-link and the material becomes a thermoset, non-reworkable material.
Nordson ASYMTEK offers several options to meet the challenges of hot-melt fluid dispensing. Our hardware solutions coordinate with the Fluidmove® software for heat controls, fluid pressure regulation, weight-controlled dispense, and mass flow calibrations for highly precise hot-melt applications.