>> Fundamental Concerning and Thoughts about the Micro-vibration Design for Advanced Industrial Plant

As we all know about the advanced industrial plant, micro-vibration always holds a crucial point to product yield concern. L&K might not be the expert in this field but after so many years’ experience working side by side with our client, L&K is fortune enough to know few.

In this edition, we would like to talk about different view and suggestions on micro-vibration based on our past experience and the hybrid concern of operation of cleanroom. 

 

>> Preface

Preface

The traditional approach of micro-vibration design is simply base on strength of building structure and level requirement of micro-vibration. However, based on our past experience of cleanroom operation, we found it seems not so straight as we think, especially accompanying the advanced generation of TFT industry. The cleanroom size for advanced generation of TFT industry becomes huge and then some interactions clearly exist between different micro-vibration control approaches and overall air flow pattern of cleanroom.

Here not only will traditional micro-vibration concern be discussed here, but some other standpoints will also be integrated for your further reference.

 

>> Fundamental Concerning of Micro-vibration Design

Fundamental Concerning of Micro-vibration Design

A simplest way to review the micro-vibration design is to check the thickness of slab. This is highly related to the vertical direction of vibration. On the other hand, the horizontal direction of vibration is related to the number, arrangement and height of columns. (In fact, the vertical direction of vibration is also related to the number and arrangement columns.)

Based on the above fundamental rules, more columns and lower height of column are used, the better level of micro-vibration could be gained. 

 

>> Other Considerations

Other Considerations

However, a smooth operation of production line does not only depend on the successful design of micro-vibration.

Accompanying the progress of new generation of TFT industry, the width of cleanroom is wider and wider and then the return air path is also longer and longer.  If the height of return air plenum (height of column) could not be suitably designed, what will be suffered in the production area is the air flow pattern problem, that is, the dirty air going into clean production zone.  For further concerning of the blocking of groups of ducting systems in the return air plenum, if the height of return air plenum is not high enough, it is possible that the dirty air originally flowing in return air plenum might come up into upstairs of clean production zone.  We had such kind of experiences in the past.

The result of air flow pattern deviation is the defect problem of products, like particle contamination or chemical spreading and contamination.

However, as discussed before, the concerning of height of return air plenum is conflicting to the requirement of micro-vibration design.

Another important concerning is cost.  It is very easy to imagine a lower height of return air plenum and thinner thickness of slab make lower initial construction cost.  However, these factors are related to the requirement of micro-vibration level.

 

>> Summary

  Summary

Here a matrix summarized table is proposed based on the architecture structure of plant with integration of different standpoints of concern, including micro-vibration.

Summarized Table for Micro-vibration Control

>> Conclusions

Conclusions

What wants to be emphasized here is micro-vibration design is not recommended to be considered independently.  In fact, it is highly related to the other operation factors of cleanroom.

We just try to consider them systematically by the integration of relating influences. Any suggestion and recommendation are highly appreciated !