50 Years, 50 Articles



Yoshihiko Yajima, Katsunori Homma, Goro Nakamura, Tetsuo Momose, Shuji Fujii


Particulate Contamination, Surface Particle Cleanliness, Measurement Technology, Measuring Instrument, Surface Particle Counter, Metrology


Particulate contaminants (Size: ca. 10 – 100 m) can cause quality defects in the products of many
industries, such as optical machine assembly and the coating process in car production. There are some
methods to evaluate such particulate contaminants that have fallen down from the atmosphere. One of them
is exposing a sampling plate and evaluating the surface particle cleanliness (SPC) on it. However, there is no
measurement instrument that can be widely applied for various industries, therefore the development of such
an instrument has been desired with low cost, easy operation, and short measurement time. We developed a
new measurement instrument, Surface Particle Counter which can measure surface particle concentration on
a plate. It can be also applicable to ISO/FDIS 14644-9.
According to our evaluation, the counting efficiency is equivalent to the discrete-particle-counting, light
scattering instrument. The concentration results measured by our new measurement instrument are also
reasonable compared to a conventional microscope method in case the particle concentrations are varied.
The measurement time is about 60 sec which is significantly shorter than the conventional methods. The
operation is also very simple and easy.
Our new measuring instrument can replace the conventional methods for the measurement of such particle
contaminants in electronics and machinery industries.


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