Aqueous Technologies Stencil & Misprint Cleaning Machine Stencilwasher ECO

The StencilWasher ECO is engineered to remove dried solder paste and mis-prints from stencils, screens and printed circuit board (PCB) assemblies. It uses ultrasonic cleaning at ~40 kHz to effectively lift residues from fine-pitch apertures and surfaces. In the rinse tank, using deionised (DI) water is critical because it eliminates ionic contamination and prevents deposit of minerals or dissolved metals which might remain on the stencil surface. A clean rinse with DI water therefore ensures that post-wash residual ions (which can degrade soldering or cause defects) are minimised.

In the wash stage the machine uses side-mounted sweep-frequency ultrasonic transducers to deliver focused sound waves into stencil apertures and around mis-print zones, dislodging solder paste and uncured adhesives. Following this, the rinse tank uses filtered water and optionally DI rinse to flush away the loosened residues. The DI-water rinse step helps ensure no mineral or ionic residues remain which could interfere with subsequent solder paste deposition or stencil life.

The StencilWasher ECO accommodates stencils up to approximately 29″ x 29″ (74 cm x 74 cm) in size with immersion depth around 25″ x 29″. For the rinse system, while tap water may be used, to meet higher cleanliness standards and avoid potential ionic contamination or re-deposition of minerals, a DI water supply or DI water polishing stage is recommended especially in high-reliability production environments.

The StencilWasher ECO is designed for rapid throughput: typical wash cycles are under five minutes for many paste types. While using standard filtered water may not drastically affect cycle time, opting for DI-water rinse can improve final cleanliness and reduce post-process inspection time or rework. In high-mix, high-quality production, the extra rinse water quality (DI) helps maintain repeatable yield, even if cost is slightly higher.

The machine supports a variety of solder-paste chemistries including rosin (‘R’, ‘RMA’, ‘RA’), water-soluble (OA), no-clean and lead-free pastes. Even when an aqueous detergent or cleaning chemistry is used, the final rinse with DI water remains important. This is because residues from the cleaning solution (ions, surfactants, metals) can remain unless the rinse is ultra-clean. DI-water ensures a final pure surface free of conductive or corrosive deposit.

Utility requirements of the machine include standard AC power (e.g., 110 V/230 V depending on region) and a drain connection (3/4″ NPT) for rinse and waste. For optimal performance in a production line aiming for high cleanliness, ensure you have access to a DI water supply or a point-of-use DI water polishing system feeding the rinse tank. Also consider that the rinse wand/air-knife combination is supplied but the quality of rinse water (especially after filtration) will affect maintenance frequency and stencil integrity.

Maintenance items include ultrasonic transducer inspection (warranty ~10 years for transducers), filtration system for rinse and wash tanks, inspection of the solder-paste trap, and ensuring drain pumps and rinse wands remain in good condition. If rinse water is of lower quality (tap water with minerals/ions), you may experience faster deposit build-up, more frequent filter changes, and potential rework due to ionic contamination on stencils. Using DI-water rinse helps reduce the frequency of these maintenance events and improves process stability.

• The machine delivers consistent, repeatable cleaning results for stencils and misprints, which helps improve yield and reduce misprint-related defects.
• The ultrasonic wash plus high-quality rinse (especially with DI water) ensures that stencil apertures are clean, free of paste residues and ionic contamination, reducing solder bridging, poor deposition or defective solder joints.
• The DI-water rinse capability supports high-reliability manufacturing (e.g., aerospace, defence, automotive) where cleanliness specifications are stringent.
• Compared to manual cleaning (which can be inconsistent, slower, and more labour-intensive), the StencilWasher ECO ensures standardised process control, faster cycle times (<5 minutes) and better cleanliness across many cycles.