There may be fear of regulatory agencies or of customers. Cleaning most often relates to particles; increasingly, it is also concerned with Airborne Molecular Contamination (AMC) or with minimizing biofilms.

DESIGN
Effective cleaning begins with thoughtful design. For the product, this means avoiding or at least being aware of areas where contamination is likely to occur. For the cleanroom, it means consideration of materials and configuration that minimize contamination. As part of the design, we also include determining what processes will be conducted within the cleanroom and how process flow will occur. Cleanroom real estate is valuable; conducting as much cleaning as possible outside of the cleanroom is not only economical, but can also minimize cleanroom contamination.

PROVENANCE
Extrapolation is necessary, but it may not be sufficient. We may say that a new product is substantially like an existing one and use cleanliness standards and cleaning practices for the existing product as benchmarks for the new one. However, after a few generations of extrapolation, modified cleaning processes and other, more pertinent, tests for cleanliness may be required.

In cleanrooms, a design to be used for one application may not be readily adaptable to another. Cleanrooms are often reutilized for applications other than those for which they were originally designed. In such instances, it is important to take a dispassionate look at the previous use or perhaps misuse of the cleanroom and to take corrective action. It is also important to assess how the cleanroom is to be used and to make needed changes.

REQUIREMENTS
This means not just specifications and standards, but also actual performance requirements. Meeting a specification is not a substitute for logical analysis. Such analysis must involve the expected end-use of the product as well as an assessment of likely contaminants and of the consequences of contamination.