Environmental and End-User Concerns: Responsible Manufacturing in the Electronics Industry
With environmental awareness at an all time high, companies are looking for ‘greener’ options within their production processes.
In the electronics industry this could, for example, include the use of alternative raw materials or the modification of production processes to become more efficient. From a raw material perspective, concentrating on chemicals used within the electronics sector, there are an increasing number of more environmentally friendly alternatives available for design engineers to consider. In recent years, such alternatives have progressed greatly, providing real benefits, not only from an environmental perspective but also in terms of enhanced performance.
Volatile Organic Compounds (VOCs)
Global warming is a prominent topic when discussing industrial effects on the environment. Chemical products for the manufacture and protection of electronics include conformal coatings and various cleaning technologies, amongst others. Such products often contain solvents which are considered Volatile Organic Compounds, or VOCs; carbon based compounds which vaporise easily at room temperature. They are more clearly defined by the EU Solvents Emissions Directive, which states that a VOC is “any organic compound having at 20°C a vapour pressure of 0.01kPa or more, or having a corresponding volatility under the particular conditions of use.”
Man-made VOCs come from both industrial and domestic sources including emissions from oil, gas and transportation as well as general fuel consumption and solvent use. The emissions of VOCs have to be controlled due to their effect on the environment and human health. VOCs contribute towards the formation of ground-level ozone, a major component of smog. Such pollution can have many detrimental effects on the environment, in particular, damaging forests and vegetation. VOCs when not managed properly can also cause health problems. Over exposure causes them to act as irritants and in worst cases carcinogens.
The use of VOCs is monitored in Europe by the EU Solvents Emissions Directive which covers defined operations such as the manufacture of coatings, coating activities (such as PCB conformal coating) and surface cleaning. The threshold limit value for solvent quantity is 5 tonnes per year for coating activities such as PCB conformal coatings. Manufacturers whose consumption of solvent falls below these thresholds fall outside the scope of the directive. Occupational exposure limits (OELs) in the workplace will still be apparent, however. It is therefore clear that both the manufacturer and end user of solvent-containing materials, such as electronic cleaning solutions and conformal coatings, are affected by the Solvents Emissions Directive.
Cleaning is an essential process within electronics manufacture and has been used for many years to remove potentially harmful contaminants during PCB production. Such contaminants include flux, solder and adhesive residues, and other more general contaminants such as dust and debris present from other manufacturing processes. The purpose of cleaning, specifically within the rapidly expanding electronics industry, is to essentially improve product lifetime by ensuring good surface resistance and by preventing current leakage leading to PCB failure. There are many stages where cleaning is required; prior to stencilling and soldering in order to remove contaminants from the many previous production stages, after stencilling to remove excess adhesive and after soldering to remove corrosive flux residues and any excess solder paste.
There are two main categories of cleaner; solvent-based and water-based . The latter is the obvious choice for reducing VOC levels however many are supplied as ready-to-use mixtures. This in turn increases the number of containers used, therefore increasing waste and also resulting in the transportation of significant amounts of water, a major component of such ready-to-use formulations. During the product selection stage, consumers should consider the use of water-based products such as those available in the Safewash range and use concentrated products wherever possible, thereby reducing transportation requirements and waste.
It should also be noted that in industry today, many manufacturers are turning to ‘no clean’ processes, implying that cleaning is not required after soldering. In the ‘no clean’ process the solids content of the flux is lower than traditional types, however they still contain rosin and activator which are not removed prior to the next process, such as coating or encapsulation of the PCB. Such residues, along with any other unwanted elements collected due to the missing cleaning stage, could cause issues with adhesion and possibly affect the performance of the protecting media applied.
The use of protection media such as conformal coatings and encapsulation resins also covers another essential process within the PCB process. Newly manufactured and cleaned printed circuit boards will generally perform well electrically, but performance will quickly deteriorate due to adsorption of atmospheric moisture, contamination of the surface with airborne ionic material, electrostatic attraction of dust to the surface etc. Conformal coatings are designed to ‘conform’ to the contours of the board allowing for excellent protection and coverage, ultimately extending the working life of the PCB. Traditionally, the most widely used conformal coatings tend to be solvent based and are available in several distinct chemical types; acrylic, silicone (conventional and silicone alkyds), epoxy and polyurethane.
The properties of a conformal coating stem from the selected base resin and the various additives included optimising the performance of the cured coating. Organic solvents are used to dissolve the base resin and reduce viscosity to bring the coating within a workable range. As such, the coating dries by simple solvent evaporation and in some cases can be further heat or moisture cured to initiate cross linking, further enhancing the coating properties. Recent changes have seen other technologies being used to avoid the inclusion of organic solvents and have resulted in the introduction of water-based, UV cure and moisture cure systems. Some alternatives have struggled to meet the high-level specifications set out by the traditional solvent-based coatings and significant adjustments to production processes may be required. Further advances have been made in this area, however and some non-VOC alternatives are available as very close replacements. It is important that consumers carefully evaluate all options available, considering the specification to be met and the production processes available. Consultation with conformal coating manufacturers will assist in this process.
VOC emissions can also be monitored by considering aerosol products typically used for general maintenance and in particular, the propellants used. Propellants may be flammable or non-flammable and each will have a specified GWP (Global Warming Potential) and ODP (Ozone Depleting Potential) value; the latter of which is usually zero for most propellants in use since the Montreal and Kyoto protocols. Non-flammable propellants offer obvious safety advantages in use when compared to their flammable counterparts but they also have higher GWP values. Developments have also been made in this area and as a result a new propellant which offers the lowest GWP and non-flammable properties available has been introduced, making it the safest option for both the user and the environment. New introductions include EADH – a powerful non-flammable airduster and FREH – a non-flammable freezer spray, both available from Electrolube.
Besides solvents, other chemical products can have a detrimental effect on the environment or carry significant health and safety warnings for the user. In Europe, the REACH regulations have been initiated to monitor the use of chemical products throughout all industries. REACH (Registration, Evaluation and Authorisation of Chemicals) is an EU wide regulation that affects all areas of the chemical industry including manufacturers, importers, distributors, downstream and end users. Although REACH is complex, the main aims are clear; to improve protection and awareness regarding the risks of chemicals to human health and the environment, whilst enhancing the development of the EU chemicals industry.
Unlike previous directives and regulations, REACH assigns the responsibility for proving that a substance is safe for the specified uses to industry rather than authorities. A registration to the European Chemicals Agency (ECHA) is required for any chemical substance that is manufactured or imported into the EU in quantities greater than 1 metric tonne per company, per year, whether it is as a single substance or part of a preparation. The registration will include test data to show the effect of use of the substance on human health and the environment. Such changes have inspired responsible chemical manufacturers to introduce safer alternatives to hazardous products, offering consumers a wider selection of high specification products.
The continual monitoring of chemical products has again enhanced awareness about the products used and the complete selection available on the market. Recently, the chemical Dichloromethane (DCM) has been banned from use in paint strippers/coating removers in the EU due to its harmful classification; it is a category 3 carcinogen. DCM based products are classed as non-flammable and are extremely effective at removing all types of conformal coating and encapsulation resin. As a compromise, alternative products with the same level of removal power have had to be formulated containing flammable materials. The health and safety implication of using such materials has greatly reduced, however. Alternative products to DCM type materials are now available on the market, such as those found in the Electrolube range: RRS – Resin Remover Solvent and CCRG – Conformal Coating Remover Gel. Both products are fast-acting with comparable performance to traditional DCM based removers but in a much more user-friendly system.
To summarise, environmental awareness is at the forefront of individual, organisational and governmental concerns alike and as a result there are many legislations monitoring the use of chemical products in a variety of sectors. This review has discussed how significant improvements can be made in terms of environmental and end-user effects by reviewing products used within the electronics industry for cleaning, conformal coating, encapsulation and general maintenance, amongst others. Manufacturers and consumers can reduce their carbon footprints by ensuring processes are efficient and energy consumption is kept at the minimum operating level; careful consideration in product selection and use can also assist in improved efficiency. In addition, transportation and packaging of goods can be monitored and sourcing environmentally friendly options, such as the use of concentrates and low/zero VOC products, all make a significant reduction to the impact on the environment. By being aware of the products used and the advantages of less harmful alternatives, companies can also provide a safer place to work and in some cases enhance the performance of their products. Electrolube continue to make a significant contribution in all of these areas by providing high specification electrochemicals that fully consider performance requirements as well as environmental and end-user safety, thereby providing a simple route to a greener future.
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