Versatile conformal coating applicators - 23 October 2019 - Techmet

Versatile conformal coating applicators
23 October 2019, Manufacturing / Production Technology, Hardware & Services

The Select Coat applicator series from Nordson Asymtek – which includes the SC-350 Select Spray and the SC-300 Multi-Mode – is a highly versatile conformal coating applicator that supports a wide range of fluid viscosities and is ideal for solvent or solvent-less fluid formulations. The series features fast system on/off times to optimise start and stop movements; and an optional four-position tilt accessory and dual-simultaneous bracket configuration that delivers improved throughput and reduced process time.

The SC-350 Select Spray is specifically optimised to atomise coating fluids – delivering enhanced edge definition and thin, uniform coating thicknesses at increased speeds. It offers additional flexibility within process parameters at the low and high end of the viscosity spectrum exclusively for atomised spray. It efficiently sprays solvent-based fluids while reducing solvent usage and the ‘cobwebbing’ effect that occurs when coating fluids cure in air. In the higher viscosity range, the applicator provides uniform pass coverage at faster speeds.

With the SC-350, the air assist function is optimised to deliver significant edge tolerance, fluid viscosity, and coating velocity improvements. The applicator applies less air pressure to achieve a tighter edge tolerance, providing increased selectivity and control near keep-out zones and reduced ‘cobwebbing’ of solvent-based fluids.

The versatile SC-300 Multi-Mode offers bead, monofilament, and swirl modes of operation that are ideal for applications that require spot coating, broad pattern widths, and thin film builds.

In bead mode, a stream of material is applied to the circuit board in areas where components are very close to non-coating or keep-out areas, or extra material is required for protection of high-impedance areas. The bead may also be used as a spot command for single coating of a single test point or component.

In monofilament mode, this pattern is created by controlling the fluid pressure and material flow passing through the nozzle. Auxiliary air circulating through the air passage strikes the material at a precise angle, causing it to spin on its axis and form a conical, looping pattern. The monofilament pattern is ideal for dispensing broad pattern widths while maintaining good edge definition, resulting in faster cycle times.

The swirl pattern is a coarse atomised spray achieved by increasing air pressure and lowering flow settings. Angled jets impinge air upon the pressurised material exiting the nozzle, creating a conical, swirling pattern. The mode is ideal for applications where moderate selective coating is required. The swirling action helps maintain pattern shape, resulting in excellent width control. Because the air jets cause slight atomisation of the material, extremely thin film builds are possible.

Delivering uniform thicknesses and consistent pattern widths for a wide range of fluid viscosities, Select Coat applicators can be configured to meet a variety of application requirements including spot, line, area-coat, and optimised atomisation.