OUTLINE
Surface contaminants can significantly effect soldering, bonding, coating and the electrical characteristics of circuit board and assemblies. This procedure outlines a batch cleaning process for the removal of the small volumes of fluxes and other contaminants that may contact circuit boards during routine circuit board repair and rework operations. This batch cleaning procedure is not necessarily appropriate for the removal of contaminants used during full assembly operations.

ACCEPTABILITY REFERENCES
IPC-A-610	7.0	Cleanliness
PROCEDURE REFERENCE
CTC 7721	1.0	Foreword
CTC 7721	2.1	Handling Electronic Assemblies

CAUTION
Aqueous batch cleaning may not always be suitable for removing rosin based fluxes or other contaminants that are not readily soluble in water.

CAUTION
Aqueous cleaning will expose all areas of a circuit board assembly to penetrating water spray. Circuit boards must be assessed regarding damage to coatings and devices that may be sensitive to deionized water.

TOOLS & MATERIALS
Batch Water Cleaning System
Brushes
Deionizing Water Filter System
Gloves
Oven
Wipes

Daily System Setup

1. Check and record the meg ohm reading of the water exiting the deionizing filter tanks. Reading should always exceed 1 meg ohm. Immediately change filter tanks if reading drops below 1 megohm.
2. With the unit empty, run the batch cleaning system through 3 cycles at the start of each day. Check the following:
   • Water Pressure: 20 PSI +/- 5 PSI
   • Water Reservoir Temperature: 120 °F to 140 °F

Operation

1. Remove any loose items from circuit boards and place circuit boards in suitable cleaning rack. Circuit boards should be placed within the rack at a minimum 45° angle to ensure proper rinse run off.
2. Place the rack within the batch cleaning system and run through the cleaning cycle. Cycle temperature and cycle times follow:
   • Wash Cycle Temperature: 120 °F to 140 °F
   • Wash Cycle Time: 75 to 85 seconds
   • Rinse Cycle Temperature: 120 °F to 140 °F
   • Rinse Cycle Time: 10 to 30 seconds
3. Remove the rack and visually examine circuit boards for cleanliness.
4. Dry the circuit boards in oven, if desired.

Evaluation

1. Visually check board assemblies for any evidence of residual flux or contamination. Clean again if needed.
2. Check circuit board assemblies for any loose items. Reattach items removed prior to cleaning if needed.