Aqueous And Semi -Aqueous Alternatives For CFC-113 And Methyl Chloroform Cleaning Of Printed Circuit Board Assemblies
l ICOLP is the Industry Cooperative for Ozone Layer Protection. ICOLP corporate member companies include AT&T, Boeing Company. We would like to thank the many individuals and companies that provided insight and information that helped produce this manual. ii iii Disclaimer The U.S. Environmental Protection Agency (EPA), the Industry Cooperative for Ozone Layer Protection (ICOLP), the ICOLP committee members, and the companies that employ the ICOLP committee members do not endorse the cleaning performance. worker safety, or environmental acceptability of any of the technical options discussed. Every cleaning operation requires consideration of worker safety and proper disposal of contaminants and waste products generated from the cleaning processes. Moreover, as work continues. including additional toxicity testing and evaluation under Section 612 (Safe Alternatives Policy) of the Clean Air Act Amendments of 1990 and elsewhere, more information on the health, environmental. and safety effects of alternatives will become available for use in selecting among the alternatives discussed in this document. EPA and ICOLP, in furnishing or distributing this information, do not make any warranty or representation, either express or implied, with respect to its accuracy. completeness, or utility; nor does EPA and ICOLP assume any liability of any kind whatsoever resulting from the use of, or reliance upon, any information. material, or procedure contained herein, including but not limited to any claims regarding health, safety, environmental effects or fate, efficacy, or performance. made by the source of the information. Mention of any company or product in this document is for informational purposes only, and does not constitute a recommendation of any such company or product. either express or implied by EPA, ICOLP. ICOLP committee members, and the companies that employ the ICOLP committee members.
Advances in Cleaning of Surface Mount Assemblies
Non‐corrosive rosin fluxes have historically been used for telephone communications assemblies because they provide a measure of reliability even if the flux is not totally removed from the assembly. While cleaning is not always necessary from a reliability standpoint, testing issues, product appearance, operating performance and customer requirements must also be considered when making the decision whether or not to clean. As the electronics industry packages more and more functionality on less and less real estate, soldering yields need to increase in order for the assembly process to remain profitable. This requires not only attention to the product's design for manufacturing but it may also require aggressive fluxes to be used in the assembly process. When aggressive fluxes are employed, the necessity for cleaning is greatly increased. The particular combination of flux and cleaning option depends on product design, process capabilities, end point requirements, and environmental considerations. Pending restrictions on the production and use of chlorofluorocarbons (CFCs), and the potential for tighter controls on chlorinated solvents and aqueous detergent effluents, are certain to add to the cost of standard processes. For these reasons alternative cleaning processes have been explored. The evaluation and subsequent use of water soluble flux with ‘water only’ cleaning, terpene cleaning of rosin flux residues, low solids flux ‘no‐clean’ wave soldering and ‘no‐clean’ assembly using reflowed rosin based solder pastes within AT&T are reviewed. A user's assessment of aqueous and semi‐aqueous cleaning is presented which indicates that there are acceptable alternatives to CFCs.
Structure of the integument of southern right whales, Eubalaena australis
Skin (integument) anatomy reflects adaptations to particular environments. It is hypothesized that cetacean (whale) integument will show unique anatomical adaptations to an aquatic environment, particularly regarding differences in temperature, density, and pressure. In this study, the gross and histological structure of the southern right whale integument is described and compared with terrestrial mammals and previous descriptions of mysticete (baleen whale) and odontocete (toothed whale) species. Samples were taken of the integument of 98 free‐swimming southern right whales, Eubalaena australis, and examined by both light and electron microscopy. Results show that three epidermal layers are present, with the stratum corneum being parakeratotic in nature. As in bowhead whales, southern right whales possess an acanthotic epidermis and a notably thick hypodermis, with epidermal rods and extensive papillomatosis. However, unlike bowhead whales, southern right whales possess an uninterrupted hypodermal layer. Surprisingly, the integument of balaenids (right and bowhead mysticetes) in general is more like that of odontocetes than that of the more closely related balaenopterids (rorqual mysticetes). Similarities to odontocetes were found specifically in the collagen fibers in a fat‐free zone of the reticular dermal layer and the elastic fibers in the dermal and hypodermal layers. Callosities, a distinctive feature of this genus, have a slightly thicker stratum corneum and are usually associated with hairs that have innervated and vascularized follicles. These hairs may function as vibrissae, thus aiding in aquatic foraging by allowing rapid detection of changes in prey density. Although the thick insulatory integument makes right whales bulky and slow‐moving, it is an adaptation for living in cold water. Epidermal thickness, presence of epidermal rods, and callosities may act as barriers against mechanical injury from bodily contact with conspecifics or hard surfaces in the environment (e.g., rocks, ice). Anat Rec, 290:596–613, 2007. © 2007 Wiley‐Liss, Inc.