No. 2.2.1
Cleaning, Local
OUTLINE
Surface contaminants can significantly effect soldering, bonding, coating and
the electrical characteristics of printed board and assemblies. This procedure
outlines the cleaning methods for circuit boards and assemblies.
NASCWPNS Final report for NON-ODS cleaning of electronics and avionics report
of October 1, 1995.
LIMITATIONS
- The ability of solvent based cleaning solutions to remove flux residue
containing polyglycols should be assessed since not all solvent based cleaning
solutions will remove polyglycols.
- A deionized water rinse should follow IPA/DI cleaning except that a water
rinse for double sided circuit boards with plated through holes may not be required.
- Potable (drinking) water should not be used as a final rinse due to the
potential of contaminating the circuit board assembly with chlorine, fluorine and
halides.
- When automated cleaning is used for assemblies that have been conformally
coated, it is important that the cleaning process is compatible with the type of
coating used and with any unsealed components. The coating should be checked to
ensure that the coating will not be degraded by the cleaning process.
TOOLS & MATERIALS
Black Light
Brushes
Cleaner, Aqueous or Semi-Aqueous
Containers
Gloves
Isopropyl Alcohol (IPA)
Oven
Wipes
PROCEDURES
CAUTION
Use clean gloves during this entire operation.
NOTE
To reduce solvent volumes, mixtures of IPA with water and IPA with solvent are
available in pressurized containers. The propellants are HFC's. These containers
may be fitted with a bristle brush spray attachments for additional cleaning
action.
- Clean the board in an Aqueous or Semi-Aqueous cleaner, or pour approximately
10 ml per 4 square inches of effected area.
- Scrub the board vigorously with a continually wet soft bristle brush for 10
seconds.
- Rinse the area with 10 ml per 4 square inches of clean Isopropyl Alcohol to
effectively remove all potentially harmful residues.
- Handle the board by the edges and blot the excess Isopropyl Alcohol with
clean, lint free cloth
- Examine board visually for cleanliness. The use of a black light will help
detect contaminants that will fluoresce.
- Dry boards in oven, if desired.
- If the boards or assemblies are to be stored before use or coating, remove
them from the oven and allow to cool until they can be handled. Place the boards
or assemblies into self sealing bags with packages of desiccant.
EVALUATION
- Visually examine and test for cleanliness using IPC-TM-650, test method
2.3.25 or 2.3.26
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Solutions Across the Board
TM
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Product Class: R/F/W/C
Skill Level: Intermediate
Conformance Level: High
Revision: E
Revision Date: May 8, 2001
Repair Service Charge
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