2.3.6 Coating Removal, Micro Blasting Method
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This coating removal method uses a micro abrasive blasting
system and a very fine soft abrasive powder. The powder
is propelled through a small nozzle toward the area
where the coating needs to be removed. To determine
the appropriate coating removal procedure the coating
must first be identified. Refer to procedure number
2.3.1.
Caution
Micro blasting will generate substantial static charges.
The work area should be flooded with ionized air and
the circuit board assembly should be grounded whenever
possible.
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Coating Removal Required
At Outlined Area |
Tools and Materials
Abrasive Powder
Micro Blasting System
Masking Tape
Procedure 2.3.6 Coating Removal, Grinding/Scraping
Method
Figure 1: Apply Kapton tape to outline area for coating
removal.
Figure 2: Remove coating using
micro blasting system.
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| 1. |
Clean the area.
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| 2. |
Select the
appropriate abrasive blasting powder and nozzle
size. Set the air pressure at the desired setting
per equipment manufacturer's instructions.
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| 3. |
Apply masking tape or other
masking material to protect the circuit board
surface as needed. (See Figure 1). Masking materials
can consist of tapes, curable liquid masks or
reusable stencils.
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| 4. |
If the circuit board has
static sensitive components, insert the entire
circuit board into a shielded bag. Only the
area needing rework should be exposed. Ground
the circuit board to dissipate static charges.
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| 5. |
Insert the circuit board
into the blasting chamber and blast away the
damaged or unwanted coating\solder mask. Slowly
move the nozzle along the area where the coating
is to be removed. (See Figure 2).
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| 6. |
Blow off the blasting dust and
clean the area |
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Figure 3: Removal complete.
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Evaluation |
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| 1. |
Visual examination or UV light
may be used to verify complete removal of coating. |
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