This Recommended Practice (RP) applies to substrates and forms used in cleanrooms for the purpose of documentation. Specifically included are: copy paper, writing paper, labels, tags, self-adhesive notes, perforated and punched forms, envelopes, bound materials, and all printed versions thereof. This RP provides appropriate methods for assessing the cleanliness of these items insofar as their suitability for use in cleanrooms is concerned.

BACKGROUND AND PURPOSE

The tests in this RP for substrates and forms used for documentation in cleanrooms can be divided into two broad categories, one having to do with structural properties (and therefore related to function) and one having to do with contamination or cleanliness.

It is frequently necessary for both user and vendor to refer to certain structural properties of substrates and forms in order that they be minimally but accurately described. A complete list of all possible structural properties would be without either end or agreement. Furthermore, different tests for these properties abound, many of which address the same issue from different points of view. The Technical Association of the Pulp and Paper Industry (tappi) and the American Society for Testing and Materials (astm) have compiled extensive lists of standard methods for evaluating many of the structural properties of paper and similar products. A selection of some of these tests for the more important structural properties, along with a brief description of each test method, is given in section 5. These tests are included in this RP not to suggest that any or all of them must be known or specified, but rather to provide both user and supplier with a common basis for testing and discussion in the event that any of these tests is specified.

While the types and sources of contaminants are virtually limitless, it is generally agreed that particles, matter extractable with solvents, and inorganic constituents are the most important considerations in high-technology applications.

Recognizing that the number of particles that can be released from a substrate is maximized when it is immersed in a liquid, a wet test for enumerating such particles is provided in section 6. The procedure quantifies the number of particles already present on and readily releasable from the surface of a substrate by wetting it with a liquid while avoiding the administration of mechanical energy. Although it is recognized that particles not already present can be generated in response to imparting mechanical energy to a substrate, no test has as yet been agreed upon for enumerating such particles.

Section 7 provides tests for the quantitative analysis of extractable matter. A procedure for determining the total burden of unspecified extractable matter is given in section 7.1, while section 7.2 provides guidelines for the quantitative analysis of specific constituents. A method for determining high-temperature ash, an excellent indicator of the total amount of inorganic species present, is described in 7.3. This last test is particularly useful in the selection of substrates and forms for cleanroom applications, because such items frequently contain high levels of inorganic fillers which have been added to impart opacity.