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Cleaning or defluxing of populated printed circuit boards has become a very difficult problem as component stand‐off clearances have become smaller, line spacings tighter, and solvents limited because of the CFC/ozone issue. This paper discusses the new technology of Centrifugal cleaning where ACCEL Energy™ is harnessed inside an enclosed chamber to provide significant cleaning benefits. Among these benefits are: superior washing, effective rinsing, superior drying, reduced solvent consumption by orders of magnitude, small footprint, and compatibility with H2O, saponifiers, chlorocarbons, fluorocarbons and terpenes.

The options for eliminating CFC‐113 as a solvent for cleaning flux residues from soldered circuit assemblies, or minimising the need to clean, are now clear: diluted CFC solvent blends, new HCFC solvents, alcohols, water plus saponifier, water with water‐soluble flux, semi‐aqueous solvents, ‘no‐clean’ fluxes and controlled atmosphere soldering. This paper summarises the advantages and the limitations of each option and presents a methodology (first suggested by Northern Telecom) for ranking the options in a way that is specific to the requirements of the user. Both the cost and the technical feasibility of the implementation of each option are considered to provide a quantitative measure that can form the basis for the decision making ‘which option best fits my requirements and my resources?’

SMT stencil cleaning has traditionally been thought of as a ‘maintenance’ procedure with little or no impact on production. Today, CFC and VOC cleaning processes are being replaced because of environmental concerns, and fine‐pitch and ultra fine‐pitch assemblies are commonplace. These changes in cleaning processes and product specifications have shed new light on the importance of properly cleaning SMT screens and stencils in order to prevent damage to the stencil and potential production‐related problems.This paper takes an unbiased look at the different stencil cleaning processes available through the eyes of an SMT stencil manufacturer. The paper outlines the advantages and disadvantages of using ‘jet spray’ washersvs ‘ultrasonic’ washers, aqueous and semi‐aqueous vssolvent cleaning agents, and the effects of hot wash solutions and hot drying air vsambient wash solutions and drying techniques.Specific criteria evaluated include: cleaning effectiveness of the process; potential adverse effects of the process on the integrity of the stencil; production down‐time and other potential production‐related problems; potential health hazards to users; environmental impact of the process, and waste stream management.Magnified photography is used to demonstrate the relative effectiveness of various cleaning technologies. Third party references of other industry experts, along with the author's own experiences, are cited to support the information provided.

In August 1987, the EPA held a conference in Washington DC with consultants and users from the electronics industry to determine the feasibility of practical cleaning alternatives to reduce emissions of chlorofluorocarbon solvents which are considered to be a major contributor to the ozone problem in the stratosphere the world over. This paper presents a short resume of these goals and how they will affect cleaning in the electronics industry. Electronic design and packaging are the first steps in the soldering and cleaning processes. Selection of components compatible with alternative cleaning methods as well as process changes to permit low solids fluxes in some cases where cleaning can be eliminated will be discussed. ‘High containment’ in‐line solvent cleaning systems which reduce emissions are likely to become the new standard for the industry. Machines will become longer in order to include internal drying stages, instead of allowing a board with residual solvent trapped under components to evaporate after it leaves the machine prior to electronic test. Alternative solvents will become available. Designers of components and assemblies will respecify their designs to permit water cleaning, even for surface mount assemblies.

The transition to surface mounted device (SMD) technology in electronics manufacturing has placed new demands on the post‐solder cleaning process. For spacecraft electronic systems it is of the utmost importance that all flux residues be removed. This paper reports the results of an investigation of the impact of component stand‐off heights and the distance between solder joints on the cleaning process efficiency. The capability to clean beneath large chip carriers was evaluated for four different cleaning methods using isopropanol or CFC‐113 (Freon TMS) as cleaning liquid. The results show that the cleaning efficiency decreases considerably if the stand‐off height is less than 240 µm for 100 mil pitch chip carriers. For 50 mil pitch chip carriers the stand‐off height needs to be greater than 240 µm to achieve high cleaning efficiency. The cleaning efficiency beneath chip carriers with small stand‐off heights can be increased by using ultrasonic cleaning. However, a very thin layer of white residues is left where the flux has been removed if isopropanol is used as the cleaning liquid.

This paper aims to discuss the effects of ionic contaminations on the die surface of high lead flip chip ball grid array (FCBGA) package. Ionic contaminations from the flux residue, formed during the die attachment process, could affect the package long‐term performance.

Thus, the flux‐cleaning process was implemented and the cleanliness effect was evaluated. Cleaning experiments using a new water‐based solvent were carried out to investigate the flux‐cleaning efficiency. The test packages were then evaluated via ion chromatography (IC).

Ion chromatograms show that there are high levels of ionic elements detected prior to the cleaning process. After the cleaning process, the contamination levels reduced significantly.

The value of the work here is testing of the new environmental friendly water‐based MPC^® cleaning efficiency. The reduction of ionic contamination is thus reported.

On the whole, commercial and public buildings regularly have their windows cleaned. For many of them, exterior cleaning stops there. But is exterior cleaning sufficiently important to receive part of an already tight facilities budget — perhaps at the expense of something more significant?

Cleaning costs represent 6 per cent of total building occupancy costs (excluding rent and rates) as our month by month Economic review pie charts showed. A massive 40 per cent of those cleaning costs may be attributed to floor cleaning (Facilities 1/2 p5) — a significant portion of the costs in use of the building and one that merits detailed analysis.

Discusses the problems and characteristics in providing cleaning services for difficult sites, using examples of a small shopping centre and an urban housing estate. Considers the specification of cleaning services, cleaning times and attendance levels, prescribing equipment and materials, problem solving, and monitoring. Concludes that just as much as every client needs a good contractor, every contractor needs a good client to run a successful cleaning programme on a difficult site.

Stencil cleaning has become both more difficult and more critical for modern surface mount technology. There is an increasing need for cleaning agents for stencils which are effective, safe for workers and safe for the environment. This paper describes a new laboratory test which was developed for predicting the performance of stencil cleaning formulations. A new aqueous, inorganic based cleaning agent has been developed which gives cleaning performance which was overall better than that of IPA. Testing was performed over a range of solder pastes. This performance advantage was confirmed with commercial stencil cleaning equipment. In addition to being very effective, this inorganic based stencil cleaner offers significant environmental and worker safety advantages.