PDF Print E-mail

1.2 Particle

1.2.1 Dust and Particles to be controlled in cleanroom

The dust and particles controlled in cleanroom are very small and invisible as shown below. Visible article is generally larger than 10 μm, which is removed out at the pre-filter stage. The cleanroom
sub-micron particle, smaller than 1 μm, is the subject to control.

According to the United States Federal Standard, the cleanliness is defined on the basis of 0.5 μm particle in diameter. That means, a cleanroom of class 1000, has a controlled environment with less
than 1000 particles per ft3 of the 0.5 μm particle size.

In the figure below, around 0.5 μm particles are smog, oil mist, cigarette smoke, etc. These are in sight only when they condense. In the cleanroom, the subjects are so small particles that they cannot
be visible without using microscope.

HEPA filter used in cleanroom can remove particles larger than 0.3 μm in diameter with more than 99.97% collection efficiency. ULPA filter, now being used in super cleanroom for semiconductor industries, has more than 99.999% efficiency for 0.1 μm particle and is able to maintain the supply air free from particles.
 

Your are currently browsing this site with Internet Explorer 6 (IE6).

Your current web browser must be updated to version 7 of Internet Explorer (IE7) to take advantage of all of template's capabilities.

Why should I upgrade to Internet Explorer 7? Microsoft has redesigned Internet Explorer from the ground up, with better security, new capabilities, and a whole new interface. Many changes resulted from the feedback of millions of users who tested prerelease versions of the new browser. The most compelling reason to upgrade is the improved security. The Internet of today is not the Internet of five years ago. There are dangers that simply didn't exist back in 2001, when Internet Explorer 6 was released to the world. Internet Explorer 7 makes surfing the web fundamentally safer by offering greater protection against viruses, spyware, and other online risks.

Get free downloads for Internet Explorer 7, including recommended updates as they become available. To download Internet Explorer 7 in the language of your choice, please visit the Internet Explorer 7 worldwide page.