Low Cost Automation Tutorial

#112 Clean Room Compatible LCA - 3: Cleanliness Localization Technology

Category : Clean room technology

April 6, 2012

In order to attain cost effective clean environments, creating clean spaces only where needed. Cleanliness localization technology fits this concept. Here, cleanliness localization by LCA concepts, unlike the micro environment (SMIF and etc.) explained in Vol. 242 Clean room compatible LCA - 2: Standard structure of clean rooms, will be explained.

(1) Cleanliness localization technology

Cleanliness localization technology is a concept of designing and creating simplified clean environments appropriate only for the subjects. There are following 3 representative types.

[Table 1] Types of cleanliness localization

Cleanliness localization type

Characteristic

App. example

Pressurized turbulence type ([Fig1 - a])

・	Clean technology for cases where the work is performed from the front side of the bench
・	Filter unit is placed above or in front

・	Inspection work bench inside of a clean room
・	Work bench for precision parts assembly

Simplified clean booth ([Fig.1 - b])

・	For cases where stable cleanliness is desired by manually handling then automating.
・	Human-less operation can achieve stable cleanliness

・	Product pre-shipping inspection and packaging
・	Localized automated equipment booth
・	For engineering evaluation

Simplified clean spot type
([Fig.1 - c])

・	When independent equipment only is desired to be clean
・	Not affected by surrounding environment

・	Clean booth for specialized machines
・	Clean booths with temp./humidity controls

[Fig.1] Types of Cleanliness localization

(2) Vital points on simplified clean booth design and construction for cleanliness localization

Basics for simplified clean booth design are the same as Cleanliness 3 principles. The vital points for the designs are as follows in the table. Since the subject is invisible minute contamination flow, the objective is to obtain the best condition by adjusting the flow of clean air, rather than aiming for a perfect condition with a first shot.

[Table 2] Vitals of simplified clean booth design and construction

Vitals of simplified clean booth design

Improvement examples

Do not create any congestion of air from HEPA filter unit

・	Provide slopes on corners inside the booth to create clean air flow

Direct clean air flow where needed

・	Create direct flows with anti-static treated sheets (non PVC sheets: HPEDT) ([Fig.3])

Locate exhausts where clean air is easily expelled out

・	Locate them on the booth bottom according to the clean air flow

Avoid using materials inside of the booth that can collect contamination

・	Use shade-less lamps on ceiling
・	Use non-rusting punched material for the bench
・	Plastics are to be anti-static treated

Use booth construction materials that can be grounded to avoid static attraction of contaminants

・	Plastics are to be anti-static treated
・	Surface treated aluminum frame surfaces are non-conductive, so use conductive bolts to tie them to the base material to make conductive.

[Fig.2] Vitals on simplified clean booth design and construction
<Do not create clean air congestion>

[Fig.3] Vitals on simplified clean booth design and construction
< Direct clean air flow where needed>

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