Transcript Chemical Processing

Dataplate Training
Chemical Processing
for Nadcap
Water Break Test Awareness
By Konrad Burgoyne
DTP-WBTA Issue 1 – 27 January 2012
Copyright © Dataplate 2001 - 2012
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Hydrophobic & Hydrophilic Conditions
Surface conditions in relation to acceptance of
aqueous (water) based liquid can be in two states
Hydrophobic
Hydrophilic
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Hydrophobic Surface Condition
Water or other water based liquid is repelled by the surface of
the parts causing the water to bead on the surface indicating
the part surface is not in a condition to interface with
aqueous based chemistry. The most common cause is grease
and oil.
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Hydrophilic Surface Condition
Water or other water based liquid is able to
“stick” to the surface of the part indicating a
water break free surface
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Hydrophobic & Hydrophilic Conditions
Hydrophilic
(Water break
free surface)
Hydrophobic
(Water broken
surface)
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Surface Cleaning



Parts cleaning is essential to many industrial processes as a
prelude to surface finishing or to protect sensitive
components.
Electroplating, anodising and conversion coatings are
particularly sensitive to part cleanliness.
Molecular layers of oil can prevent adhesion of the coating,
or in the case of anodising and chemical conversion coatings
prevent coatings from forming altogether
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Cleaning Processes
Cleaning processes include: 


Solvent cleaning
Hot alkaline detergent cleaning
Acid or alkaline etching
In Treatments we use a solvent degreaser, Hot alkaline soak
cleaner and an acid deoxidiser (mild etch) process
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Surface Conditioning
The cleaning processes within the treatments is formulated to
enable the correct conditions to prepare the surface of parts
Parameters important to the process stages include:  Time of immersion or exposure
 Temperature to obtain optimum cleaning
 Concentration and formulation of the chemistry for optimum
cleaning capability
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Water Break Test
The water break test is an effective way to visually confirm that the surface of the
parts have been cleaned successfully and are in a condition to process further.
If the surface of a part maintains a water break free surface for 30 seconds after
immersion in clean water below 38°C it is considered clean.
The water break test requires observation of the surface of the parts following a
clean rinse stage to confirm a water break free surface is maintained for 30
seconds or more.
Parts may be visually inspected at the end of the 30 second period. This may allow
the operator to move to the next stage during the 30 second period and inspect
the parts just before the next stage.
E.g. Turco clean > Rinse > Check time for start of WBT > move to deoxidiser > Check
time until 30 seconds elapsed > Inspect water break free surface > Immerse into
deoxidiser on successful WBT
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Process Control Flow Chart PCFC /
Process Control Document PCD
The Process Control Flow
Chart (PCFC) lists each
stage of the process and
indicates where and when
a water break test is
required. The water break
test is required after the
cleaning process
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Chemical Processing for Nadcap
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