Why Bother in LPC Data for PVA Sponge Roller

Liquid Particle Counter

LPC(Liquid Particle Count) is used to understand the particle distribution within a volume of water.  Under these circumstances, engineer applies a similar technique to loosen the particle on the substrate and understand the particle distribution which distributed on the substrate surface.

Base on above, cleaning process engineer apply LPC measurement to understand the loosen particle distribution in order to examine the cleaning efficiency on particle removal.  No doubt, this is an effective tool.

Loosen particle detected by LPC tool is reported via several categories of particle size.  For instance, the LPC meter will print out the particle count for 0.2-0.5um, 0.5-1.0um, 1.0-3.0um, 3um above.  In a cleaned substrate, we normally see the highest count for 0.2-0.5um categories, and the count reduces while the particle size is getting larger

LPC Trend
LPC Trend

LPC Reading for PVA Sponge

Could we measure the LPC for a PVA sponge roller?  The answer is certain.  Perhaps in our factory, we do measure LPC count from time to time to examine if any fundamental shift in our sponge brush product.

In our quality compliance report, we do not include the LPC as a judgement criteria to determine sponge cleanliness.  In short, sponge brush cleanliness is still very much rely on the IC test result.  The reader is encouraged to read how we determine sponge cleanliness from our relevant article.

Why LPC unable to become Judgement Criteria

LPC is a tool which could categorize a particle size to a very small extreme.  Our LPC tester can differentiate till 0.2um size.  Since LPC is so sensitive in reporting the particle distribution, a small fluctuation in particle count may not necessarily tell the difference in term of product quality level.  There is some reason we are not taking LPC particle data as our judgement for sponge cleanliness.

  1. Count Fluctuation.
  2. Sample Preparation.
  3. Measurement environment.
  4. Method to loosen the particle from the substrate.

Interpret LPC data

Data is just a data until we are able to interpret and make use the information provided.  We know some people will directly apply the data with the standard SPC technique, unfortunately, this will lead to the pitfall.

DST knows the rationale to interpret the LPC data to derive from PVA sponge roller.  We do not overreact while seeing fluctuation in LPC data.  We have to wisely interpret the data and know which part of the process is performed properly.

The cleaning process is directly affected the LPC data.  While the data is getting abnormal, we have to investigate the root cause and identify the source of contaminant.  This requires strong knowledge and experience about the PVA sponge roller product.

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