An alarming problem – the technology development of electronic pastes may bring new

environmental risks and the lack of corresponding measures

Hongzhao Liu, a……, Liqiao Chen b

a Research Centre of Western China Environment and Resources Law of Chongqing University ,

Chongqing, 400044, P. R. China.

b State Key Lab of Advanced Technology for Comprehensive Utilization of Platinum Metals,

Kunming Institute of Precious Metals, Kunming, 650106, P. R. China.

EM：chenkm2016@163.com TEL:13108835801

Abstract

The environment pollution and human health are hot social issues in recent

years ， technological progress and upgrades promote the development of society, but the

environmental risks brought by new technology development should be evaluated and controlled

in advance. Electronic pastes are a class of important materials manufactured for electronic

components. In this paper, the new environmental problems brought by technological progress and

developmentwere analyzed and discussed. Seen from the preparation routes and subsequent

damage as electronic waste to the environment, some new or greater environmental risks may

appear due to the application of nano-metal conductive powders, the development of the base

metals instead of precious metals and the trend of low temperature curing pastes. The risks are

partly from objective technical factors, and also have the reasons of the subjective consciousness.

However, the current laws and regulations have not been able to effectively control the risks.

Electronic paste is a typical high-tech industrial production. Through this case, it is pointed out

that the technology innovation and industry upgrading may be not always good to environment

and human health. Therefore, it is important to strengthen the prevention and control of the

environmental risks when bringing new technology, only in that way, the coordinated

development of social progress and environment-friendly could be realized.

KeywordsElectronic Pastes, New Environmental Risks, Nanometer Powders, Nanomaterials’

Preparation, Base Metal, Environmental RegulationIntroduction

Electronic paste is a kind of mixing pasty fluid which is composed of conductive metal

powder, inorganic or polymer binder suspended in an organic vehicle. This kind of material is

used in many electronic components to form a specific module with electrical function, such as

thick-film hybrid integrated circuits, chip components, photovoltaic cells, flexible batteries,

electro-optic devices, displays, logic and memory components—including field effect transistors

(FETs) and thin film transistors (TFTs), sensor arrays, radio frequency identification (RFID) tags

and other components. We can say that electronic pastes almost exist in all of the electrical and

electronic equipment. In the process of the preparation and use for electronic paste, volatile

organic compounds evaporate into the air pollution, and the remaining ingredients along with

electronic components are discarded as electronic waste. With the rapid development of modern

electronics and information technology, the technical updating for electronic paste is an inevitable

choice to meet this requirement of electronic productions.

At the same time, with the development of science and technology, natural environmental is

destructed, and environmental pollution and human health has attracted wide attention of society.

After the industrial revolution, humans have entered the era of risk. The risk precaution principle

has become a global consensus. How to strengthen the technical risk assessment and management

in the progress of science and technology has become a common problem that mankind must face.

Volatilization of organic compounds and e-waste from electronic products are the important

factors of damage on environmental health. For these health problems caused by environmental

pollution, environmental researchers carry out many studies on pollution sources, harm and harm

mechanism and recycling of pollutants. Environmental protection departments have also

developed a number of appropriate management of preventive measures around the social issues.

These research and management section produce a certain effect on the control of electronic waste

pollution, lead-free, cadmium-free, halogen-free products are as the result of green processing for

electronic paste in recent years. However, the conductive paste as an important raw material for

electronic industry, its technological development first should meet the requirement of the

technical progress and upgrade of electronic components, so it cannot develop isolatedly toward

the environment-friendly direction.

At present, miniaturization, low temperature, flexibility and low-cost of manufacture is the

trend of the development of the electronic components. To meet the miniaturization of

components, the electronic paste need have higher line resolution, so the solid powders composed

for electronic paste will be smaller to nanometers sizes; To meet the trend of low temperature, the

flexibility of electronic pastes, polymer resins instead of inorganic oxides or glass frits are adopted

as the binders, and conductive phases change from micro-spherical metal powders into

nanostructures or flaky morphology; Low-cost manufacturing has pushed the base metals to be

used as a conductive phase.

In this paper, focusing on the technology updates and trends of electric pastes, the

environment risk is comparatively analyzed from two aspects: raw materials preparation and

discarded as e-waste, and the change of environment risk due to paste technology updates. At the

same time, from the perspectives of the environmental laws, regulations, the current management

measures for environmental risks of these new trends still have many problems and shortcomings,

and expect that it would draw public attention, which would help to provide technology

innovation and coordinating development of society, economy and environment.

Results and discussion

Technology development of the electronic paste exerts new threats on the environment

1. Environment risk analysis of nanometer powders as the fillers

1.1 The inevitable trend of nanometer powders as the fillers

The development of the electronic component miniaturization and integration imposes higher

requirements on the print precision and process. The development of nanopowder preparation

technology provides guarantee for this request. On the one hand, in order to meet the need of fine

screen printing process, the solid powder in electronic paste must update for nanometer sizes. On

the other hand, the gap between cost-in-use of conventional silver materials and nanosilver has

narrowed significantly, and this may encourage some customers to finally make a switch to higher

performance nanosilver technologies. Further, in recent years, printed electronics represent an

emerging area of research that promises large markets due to the ability to bypass traditional

expensive and inflexible silicon-based electronics to fabricate a variety of devices on flexible

substrates using high-throughput printing approaches. Nano-electronic ink has become an

Perelaer, J.; Smith, P. J.; Mager, D.; Soltman, D.; Volkman, S. K.; Subramanian, V.; Korvink, J. G.; Schubert, U. S.: Printed electronics: the challenges involved in printing devices, interconnects, and contacts based on inorganic materials. Journal of Materials Chemistry 2010, 20, 8446-8453. Sire, C.; Ardiaca, F.; Lepilliet, S.; Seo, J.-W. T.; Hersam, M. C.; Dambrine, G.; Happy, H.; Derycke, V.: Flexible Gigahertz Transistors Derived from Solution-Based Single-Layer Graphene. Nano Letters 2012, 12, 1184-1188.

important direction of conductor paste. Printed electronics employ either ink-jet or high-speed

printing, both of which are particularly compatible with nanopowders. NanoMarkets estimates that

the total market for nanosilver materials and coating products is valued at about $290 million in

2011, and that it will to grow over the forecast period to about $1.2 billion by 2016. In short,

nanopowders as conductive filler in electronic paste have become the inevitable development

trend of the industry.

1.2 The natural environment threats of nanometer powders itself

Electronic paste fillers include metal conductive powders and the inorganic binder, which

involves metals and some oxides. For metallic conductive phase, the case of more than 90% is

silver powder. Silver is chosen for the ideal metal-containing ink because it is cheap, easy to

prepare, store and jet, and would give high values of conductivity. Silver nanoparticles (AgNP)

are increasingly widely used in conductive pastes, subsequently released into

aquatic environments. Toxicity of engineered nanoparticles in the environment has raised a lot of

concerns. Effects of silver nanoparticles of different sizes (20, 80, 113 nm) were compared

in in vitro assays for cytotoxicity, inflammation, genotoxicity and developmental toxicity. It

showed that  silver nanoparticles of 20 nm were more toxic than the larger nanoparticles, Even

more cytotoxic than silver ions. Gold and silver particle sizes are influential in dictating the

observed toxicity, with smaller particles exhibiting a greater response than their larger

counterparts. Liyan Yin’s study suggests that growth inhibition and cell damage can be directly

attributed either to the nanoparticles themselves or to the ability of AgNPs to deliver dissolved Ag

to critical biotic receptors, and the effects of silver nanoparticles on Lolium multiflorum is more

desirable than the ions. Many other studies also showed nanosilver is more dangerous than the

larger counterparts.Spermatotoxicity of the gold nanoparticle can also be detected. The

experiment exposed to zebrafish embryos assessing mortality and developmental defects showed

http://www.giiresearch.com/press/nan205729.shtml.

dendritic Ni clusters were more toxic than soluble nickel . Acute toxicity of soluble copper and

80 nm copper nanoparticle suspensions were examined in zebrafish, and the results  clearly

demonstrated that the effects of nanocopper on gill are not mediated solely by dissolution.

Toxicity of nano-scaled aluminum, silicon, titanium and zinc oxides to bacteria (Bacillus

subtilis, Escherichia coli and Pseudomonas fluorescens) was examined and compared to that of

their respective bulk (micro-scaled) counterparts. All nanoparticles but titanium oxide showed

higher toxicity (at 20 mg/L) which was affected by bacterial attachment than their bulk

counterparts. In fact, most research findings showed nanoparticle is more toxic than the big

counterpart although the mechanism is not still clear, so someone suggest that nanoparticles

should be classified according to GHS (Globally Harmonized System of classification and

labeling of chemicals) as “category acute 1” to Daphnia neonates.

1.3 The hazards in process of nanomaterials’ preparation

In addition to environmental hazards caused by nanoparticles itself, its potential

Jang, D.; Kim, D.; Lee, B.; Kim, S.; Kang, M.; Min, D.; Moon, J.: Nanosized Glass Frit as an Adhesion Promoter for Ink-Jet Printed Conductive Patterns on Glass Substrates Annealed at High Temperatures. Advanced Functional Materials 2008, 18, 2862-2868. Maurer-Jones, M. A.; Gunsolus, I. L.; Murphy, C. J.; Haynes, C. L.: Toxicity of Engineered Nanoparticles in the Environment. Analytical Chemistry 2013, 85, 3036-3049. Park, M. V. D. Z.; Neigh, A. M.; Vermeulen, J. P.; de la Fonteyne, L. J. J.; Verharen, H. W.; Briedé, J. J.; van Loveren, H.; de Jong, W. H.: The effect of particle size on the cytotoxicity, inflammation, developmental toxicity and genotoxicity of silver nanoparticles. Biomaterials 2011, 32, 9810-9817. Yin, L.; Cheng, Y.; Espinasse, B.; Colman, B. P.; Auffan, M.; Wiesner, M.; Rose, J.; Liu, J.; Bernhardt, E. S.: More than the Ions: The Effects of Silver Nanoparticles on Lolium multiflorum. Environmental Science & Technology 2011, 45, 2360-2367. Liu, J.; Hurt, R. H.: Ion Release Kinetics and Particle Persistence in Aqueous Nano-Silver Colloids. Environmental Science & Technology 2010, 44, 2169-2175. Gil-Allué, C.; Schirmer, K.; Tlili, A.; Gessner, M. O.; Behra, R.: Silver nanoparticle effects on stream periphyton during short-term exposures. Environmental Science & Technology 2014. Völker, C.; Kämpken, I.; Boedicker, C.; Oehlmann, J.; Oetken, M.: Toxicity of silver nanoparticles and ionic silver: Comparison of adverse effects and potential toxicity mechanisms in the freshwater clam Sphaerium corneum. Nanotoxicology, 0, 1-9. Wiwanitkit, V.; Sereemaspun, A.; Rojanathanes, R.: Effect of gold nanoparticles on spermatozoa: the first world report. Fertility and Sterility 2009, 91, e7-e8. Ispas, C.; Andreescu, D.; Patel, A.; Goia, D. V.; Andreescu, S.; Wallace, K. N.: Toxicity and Developmental Defects of Different Sizes and Shape Nickel Nanoparticles in Zebrafish. Environmental Science & Technology 2009, 43, 6349-6356. Griffitt, R. J.; Weil, R.; Hyndman, K. A.; Denslow, N. D.; Powers, K.; Taylor, D.; Barber, D. S.: Exposure to Copper Nanoparticles Causes Gill Injury and Acute Lethality in Zebrafish (Danio rerio). Environmental Science & Technology 2007, 41, 8178-8186. Jiang, W.; Mashayekhi, H.; Xing, B.: Bacterial toxicity comparison between nano- and micro-scaled oxide particles. Environmental Pollution 2009, 157, 1619-1625. Asghari, S.; Johari, S.; Lee, J.; Kim, Y.; Jeon, Y.; Choi, H.; Moon, M.; Yu, I.: Toxicity of various silver nanoparticles compared to silver ions in Daphnia magna. Journal of Nanobiotechnology 2012, 10, 14.

environmental risk in process of the preparation of nanoparticles has not attracted the attention of

the society. The preparation of nanoparticles usually brings greater harm to the environment. Take

nanosilver as an example, which can be analyzed from three aspects.

1.3.1 The preparation of both small sizes and narrow particle size distribution of

powders often require some special reagent and more surfactants

The metal powder’ sizes prepared by the conventional liquid phase method are most 100

nm~5 μm. The line width of traditional thick film is about 100 μm, and the thickness of film is

about 15 μm. This means that the powders’ preparation used for traditional electronic paste is

simple, and does not need many special reagents or equipment. As the preparation route of

traditional silver powders, silver nitrate is the raw material, distilled water as solvent, ascorbic

acid, hydrazine hydrate or formaldehyde as reducing agent, and adjust the solution pH = 2~13

through sodium hydroxide or sodium carbonate. The structures of silver powder could be

controlled through some simple experimental parameters adjustment. However, reports of this

kind are rarely seen recently. Usually, the preparation of nanosilver powders have AgBFX、organic

solvent,etc. as the reagent. A mount of stabilizing agent (also known as capping agent) is used in

the synthesis process to prevent nanoparticles from aggregation and control the size of final

product. The conventional or non-green methods involve chemical agents associated with

environmental toxicity, or the process of preparing these reagents will bring environmental

harm。This is expected since non-green methods provide more control over the reaction process

and produce monodisperse silver nanoparticles with peculiar characteristics. Thabet M. Tolaymat

et al. concluded the type of silver salt, solvent, reducing agent, and stabilizing agent for the

synthesis of nanosilver. The great majority of synthesis processes are not environmentally friendly,

with only 24 % of the reported methods relying on green or environmentally-friendly techniques.

It can also be inferred that particle sizes less than 20 nm are considered the most reactive and are

seldom generated using green synthesis methods.

1.3.2 Nanoparticles preparation generally results in a lower yield

As is discussed above, the traditional silver powder can be used directly for paste without

size-selecting. For nano paste, the conductive line width is below 5μm, the inkjet printing

conductive paste (commonly known as nano-ink)， the jet diameter is below 1um, which means

that any large particles in productions would not be acceptable. Good wettability of Silver powder

with an organic vehicle is necessary so that it can be well dispersed to discrete nanoparticles in the

pastes. In order to meet these requirements, filtering process and the special surface treatment are

required. The two processes greatly reduce the yields of silver powders and increase the energy

consumption. In addition, the particle sizes for the nanosilver ink are 1 nm~50 nm,which is

the typical colloids, thus forming a uniform system that is difficult to precipitate in the solution,

causing more loss of products into the environment along with the waste water, and resulting in

the more environmental hazards.

1.3.3 The great profit margin allows manufacturers to ignore cost control

As we know, manufacturers have larger profit margin by adopting new technology because it

is more competitive . Therefore, in order to keep technical advantages, the manufacturer could use

expensive reagents and complex process method. however, the high price of the reagents are often

accompanied by danger or low yield preparation, which either directly increase the environmental

hazards, or increase energy consumption and further have a negative impact on the environment.

2. Environment impact brought by base metals being used for conductive metals instead

of precious metals

2.1 The development trend of base metal is used for conductive metals

The traditional conductive pastes mainly adopt precious metals for conductive phase, such as

gold, silver. As the improvement of processing equipment and Manufacturing technology, also due

to being driven by low cost, a significant amount of work has been devoted to development of

copper pastes and nickel pastes, although which have to be used in a H2 atmosphere. Copper,

nickel powder begin to gradually take the place of precious metals into the marked of electronic

pastes.19-21 In terms of price, an ounce of silver costs $17, whereas one ounce of copper is about

LeeKwi-jong,J.B.-H.,LeeYong--Ho,etal.Metalnanoparticleandmethodformanufacturingthemandconductiveink[P].USPat:20060254387,2006-11-16. Ankireddy, K.; Vunnam, S.; Kellar, J.; Cross, W.: Highly conductive short chain carboxylic acid encapsulated silver nanoparticle based inks for direct write technology applications. Journal of Materials Chemistry C 2013, 1, 572-579. Tolaymat, T. M.; El Badawy, A. M.; Genaidy, A.; Scheckel, K. G.; Luxton, T. P.; Suidan, M.: An evidence-based environmental perspective of manufactured silver nanoparticle in syntheses and applications: A systematic review and critical appraisal of peer-reviewed scientific papers. Science of The Total Environment 2010, 408, 999-1006. Eom, Y.-S.; Choi, K.-S.; Moon, S.-H.; Park, J.-H.; Lee, J.-H.; Moon, J.-T.: Characterization of a Hybrid Cu Paste as an Isotropic Conductive Adhesive. ETRI Journal 2011, 33, 864-870. Songping, W.: Preparation of ultra fine nickel–copper bimetallic powder for BME-MLCC. Microelectronics Journal 2007, 38, 41-46.

20 cents and nickel is approximately 53 cents, respectively. Just seen from the metal price itself,

base metals obviously have great superiority used for electronic paste, but it is not a good thing for

the environment.

2.2 The comparisons of toxics released to the environment in phase of preparation

It is easy to reduce for precious metal ions due to a high reduction potential, which provides

more space for the selection of low-cost, high environmental reducing agents. Otherwise, the base

metals of copper and nickel are with the lower reduction potential, and difficult to be reduced to

elemental generally. The standard reduction potentials of four metals are listed in the table 1.

Table1. The standard reduction potential of four kinds of metal: gold, silver, copper, and

nickel

Au3+| Au Ag+|Ag Cu2+|Cu(s) Ni2+/Ni

Standard Reduction

potentials

1.42 ev 0.7986 ev 0.3402 ev -0.257 ev

Table2. The reducing power of typical reducing agents for the preparation of gold, silver,

copper, nickel

Weak reducing agents Middle reducing agents Strong reducing agents

sugars, DMF, Amines, EG Ascorbic acid, formaldehyde

Sodium sulfite, Ferrous

sulfate 

NaBH4,  hydrazine

According to table 1 above, the reduction potential of gold, silver ion is much higher than

those of the copper, nickel. In fact, these precious metals could be almost reduced by all of the

reducing agents listed in Table 2, and also it is usually enough for only theory dosage to finish the

reducing reaction, that is to say, it is not necessary to adopt too much reducing agent. [18]

However, copper and Nickel usually can be reduced only by some toxic, strong reduce agents,

such as NaBH4 or hydrazine. The reducing power of NaBH4 is too strong to control the shape and

size of metal powders, so hydrazine hydrate is mostly adopted as reducing agent to reduce copper

Im, D.-H.; Hyun, S.-H.; Park, S.-Y.; Lee, B.-Y.; Kim, Y.-H.: Preparation of Ni paste using binary powder mixture for thick film electrodes. Materials Chemistry and Physics 2006, 96, 228-233. Mortimer, R. G.: Physical ChemistryThird Edition. 2008, 1227. Huaman, J. L. C.; Hironaka, N.; Tanaka, S.; Shinoda, K.; Miyamura, H.; Jeyadevan, B.: Size-controlled monodispersed nickel nanocrystals using 2-octanol as reducing agent. CrystEngComm 2013, 15, 729-737.

or nickel powders with the reaction temperature of more than 60 degrees. what’s more, in

order to ensure a complete reduction, the addition quantity of reducing agent is usually 2 times

larger than Theory dosage. According to the chemical reaction theory, the oxidation product of

hydrazine hydrate is N2, which is also substantially non-toxic. Thus, base metal is usually prepared

in the condition of high temperatures and excessive toxic strong reducing agents, thus bringing

direct toxic reagents and increasing energy consumption and waste of environmental resources。Therefore, in terms of environmental risk, the toxicity of the liquid preparation route for base

metal is significantly greater than that of the preparation process of the precious metal. Chemical

vapor deposition (CVD) is also used to produce high quality, high-performance, solid materials as

a chemical process. Where, the chemical agents react in the vapor phase. Obviously, the method

would bring the more serious environmental hazards due to the complex process, high reaction

temperature and plenty of by-products.

2.2.1 Manufacturers and users positively reduce the loss of precious metals due to the

price factor

Manufacturers of precious metals usually have strict internal management systems for

precious metals. Kunming Institute of Precious Metals, for example, put metal detectors in every

exit of company and all staff is required to have a security check which prevent precious metals

from being brought out. At the same time, all of the precious metals be specialized personnel, and

have a regularly check for accounts of all precious metals and enhance individual responsibility.

However, there is usually no such strict management for manufacturers of copper, nickel and other

base metals. Therefore, precious metals researcher and producer would consciously take effective

means to prevent the loss of precious metals into the environment through various ways during the

whole process. For the same reason of price, the recovery of precious metals is also more

thorough. So in terms of life cycle of the precious metals, the risks of precious metals into the

environment are much smaller than base metals.

2.2.2 Base metals would cause greater environmental harm due to its easy solubleness to

metal ions

Vahlas, C.; Caussat, B.; Serp, P.; Angelopoulos, G. N.: Principles and applications of CVD powder technology. Materials Science and Engineering: R: Reports 2006, 53, 1-72. Wang, S.; Huang, X.; He, Y.; Huang, H.; Wu, Y.; Hou, L.; Liu, X.; Yang, T.; Zou, J.; Huang, B.: Synthesis, growth mechanism and thermal stability of copper nanoparticles encapsulated by multi-layer graphene. Carbon 2012, 50, 2119-2125.

As is described above, the noble metals are rarely lost to the environment due to higher prices

in the industry, even though a small amount of into the environment, the noble metal owing to the

high chemical stability, so that it mostly existed as a form of metal elemental in the environment.

For elemental silver, although many studies have shown that it could be also dissolved into Ag +,

[8]even some think toxicity of AgNP suspensions was caused by  Ag(I) dissolved from the particles,

[9] but Ag2S-NPs are chemically stable and have profoundly low Ag liability over extended periods,

and this may minimize the long-term risks of Ag toxicity in the soil environment. Copper, nickel

is more likely to be the presence of ionic state due to elemental easily oxidized in the environment,

which itself makes the copper, nickel have a greater harm to organisms.

2.3 The new environmental problems brought by the application trend of low

temperature pastes

To meet the requirements of flexibility and low temperature fabrication of electronic

components, the low-temperature electronic paste gradually take place of the traditional high-

temperature products. As shown in table 3, high-temperature pastes are composed for

spherical silver powders commonly, with a small amount of organic solvent and inorganic binder,

additives, etc.And the low temperature pastes are mainly composed of flaky silver powders

prepared by mechanical milling, organic solvents, organic additives and other organic agents.

Table 3. The compositions of high / low temperature pastes

high-temperature pastes low temperature pastes

conductive metal powders spherical powders platy powders

binders inorganic glass frits or

oxides containing of Si, B,

epoxy-based, acrylic and

other polymer resins

V. Goia, D.; Matijevic, E.: Preparation of monodispersed metal particles. New Journal of Chemistry 1998, 22, 1203-1215. Huang, G.-y.; Xu, S.-m.; Xu, G.; Li, L.-y.; Zhang, L.-f.: Preparation of fine nickel powders via reduction of nickel hydrazine complex precursors. Transactions of Nonferrous Metals Society of China 2009, 19, 389-393. Kim, K. H.; Lee, Y. B.; Choi, E. Y.; Park, H. C.; Park, S. S.: Synthesis of nickel powders from various aqueous media through chemical reduction method. Materials Chemistry and Physics 2004, 86, 420-424. Haitao, Z.; Canying, Z.; Yansheng, Y.: Novel synthesis of copper nanoparticles: influence of the synthesis conditions on the particle size. Nanotechnology 2005, 16, 3079. Sekine, R.; Brunetti, G.; Donner, E.; Khaksar, M.; Vasilev, K.; Jämting, Å. K.; Scheckel, K. G.; Kappen, P.; Zhang, H.; Lombi, E.: Speciation and Lability of Ag-, AgCl-, and Ag2S-Nanoparticles in Soil Determined by X-ray Absorption Spectroscopy and Diffusive Gradients in Thin Films. Environmental Science & Technology 2014.

Pb, Bi, Cd, Zn, Cu, etc.

organic vehicles volatile organic solvents

and additives (10~30 wt%)

volatile organic solvents

and additives (20~60 wt%)

For metal conductive phase, flaky silver powders are used for low temperature pastes, flaky

silver powders are obtained by further mechanical milling treatment (usually 48 h ~ 96 h) based

on primarily spherical silver powders. In the process of milling, the introduction of a number of

milling additives and consumption of energy bring the greater the environment awards. For the

binders in the pastes, the binders used in the low temperature are some polymers, and for high

temperature pastes, the binders are some inorganic oxide powders or glass frits. The harms to the

environment are not directly comparable for polymers and oxides, depending on the specific

components of the slurry, so we do not demonstrate. However, for organic vehicle, obviously, the

main components of two types of pastes are similar, but the dosage of the low temperature pastes

is usually 2 times more than that of the high temperature pastes, which obviously increases the

environmental hazards of volatile organic solvent thereof. Therefore, the development trend of

low temperature pastes meet the requirements of the flexible components and the low curing

temperature, but add a lot of environmental risks in the process of preparation of the pastes.

The lack of the current policy, management measures and laws for environment risk of new

technology

Electronic pastes are a series of chemical products, involving chemical preparation and use of

metal powders, oxides or glass frits, and a variety of polymers, additives and the solvents. At the

same time, they are also used as a raw material in a variety of electronic components, afterwards,

as e-wastes into environment along with those electronic products. So the environmental risk of

Lee, Y.-I.; Kim, S.; Jung, S.-B.; Myung, N. V.; Choa, Y.-H.: Enhanced Electrical and Mechanical Properties of Silver Nanoplatelet-Based Conductive Features Direct Printed on a Flexible Substrate. ACS Applied Materials & Interfaces 2013, 5, 5908-5913. Choi, H. W.; Zhou, T.; Singh, M.; Jabbour, G. E.: Recent developments and directions in printed nanomaterials. Nanoscale 2015. Ketkar, S. A.; Umarji, G. G.; Phatak, G. J.; Ambekar, J. D.; Rao, I. C.; Mulik, U. P.; Amalnerkar, D. P.: Lead-free photoimageable silver conductor paste formulation for high density electronic packaging. Materials Science and Engineering: B 2006, 132, 215-221. Jeon, S. J.; Koo, S. M.; Hwang, S. A.: Optimization of lead- and cadmium-free front contact silver paste formulation to achieve high fill factors for industrial screen-printed Si solar cells. Solar Energy Materials and Solar Cells 2009, 93, 1103-1109. Songping, W.: Preparation of micron size flake silver powders for conductive thick films. J Mater Sci: Mater Electron 2007, 18, 447-452. Tan, F.; Qiao, X.; Chen, J.: Removal of chemisorbed lubricant on the surface of silver flakes by chemicals. Applied Surface Science 2006, 253, 703-707.

electronic paste should be analyzed from two aspects, namely, chemical pollution produced from

preparation stage and as environmental hazard electronic wastes.

1. The control regulations of chemical pollutions

Internationally, environmental regulation for the chemical pollution can be traced back to the

convention on the prevention of marine pollution by dumping of wastes at sea in 1972, also

known as the “London Dumping Convention”. The documents provided the prohibition of

dumping organic halogen compounds, mercury and mercury compounds, cadmium and cadmium

compounds and so on. With the growing aggravation of environmental pollution from chemical

products, the international community has developed “The Rotterdam Convention on the Prior

Informed Consent Procedure for Certain Hazardous Chemicals and Pesticides in International

Trade” (referred to as the Rotterdam or PIC Convention). The aims are to strengthen the global

chemical safety management, through supporting all parties to strengthen information exchange of

hazardous chemicals in international trade and to prevent illegal movements of hazardous and

toxic chemicals from causing casualties or environmental pollution. It clearly required that each

state party must control PCDF, PCDD, PCB, DDT and other twelve kinds of organic pollutants

(limiting or prohibiting use) in the documents from the convention. At present, several classes of

POPs are now regulated by international conventions which call for the implementation of

management plans at the national level. On the basis of their global presence, persistence in the

environment, bioaccumulation in biota, and toxicity, twenty-three chemicals have been enlisted as

POPs by the globally binding Stockholm Convention (SC) with the aim of limiting or prohibiting

use and production. In addition, UNEP International Conference on Chemicals Management

adopted the Strategic Approach to International Chemicals Management (SAICM) in 2006, which

aims to strengthen the international community's concern about chemical hazards to human health

and the environment, coordinating global staff to further enhance the capacity of the environment

and safety management on chemicals, and reducing the risk of chemical hazards etc. States on the

chemical study of environmental pollution regulations, most of them are based on international

conventions and principles of management of hazardous chemicals, combined with national

5 J. Mar. L. & Com. 299 (1973-1974)1972 Convention on the Prevention of Marine Pollution by Dumping of Wastes at Sea, T., Duncan, Rodney N. [ 18 pages, 299 to 316 ] www.unep.org/chemicalsandwaste/Portals/9/Mainstreaming/CostOfInaction/Report_, U. U. N. E. P. C. o. i. A. h.

conditions, from the production of chemicals, storage, use, safety management regulations to

strengthen the management and transportation etc. for example, “Toxic Substances Control Act”

was implemented in the United States since 1976, China revised “dangerous chemical safety

regulations” in 2011 and so on.

2. The management regulations of electronic wastes

Under the auspices of the United Nations Environment Programme (UNEP), on March 22,

1989, over 116 nations endorsed the Basel Convention on the Control of Transboundary

Movements of Hazardous Wastes and Their Disposal (Basel Convention). It is global treaty on

how control and reduce the risk of transboundary movement of wastes. E-waste management

system in the history of the EU countries has been relatively mature; in 2002 the EU Electronic

Waste Management Act was adopted at the EU Commission, specifically the use of extended

producer responsibility system. On this basis, the EU Member States in order to make the

restriction on the use of hazardous substances in electrical and electronic equipment law converge

to help protect human health and the waste electrical and electronic equipment environmentally

sound recycling and disposal, in 2003 introduced WEEE directives, namely waste from electric

and electronic equipment (directive 2002 /96 /EC) and the restriction of the use of certain

hazardous substances in electrical and electronic equipment(Directive 2002/95/EC). Due to

electrical and electronic products involved in a number of new chemical substances, to strengthen

the management of chemicals, June 1, 2007 the formal implementation of Regulation Concerning

the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) in the UN,

through registration, evaluation, authorization, restrictions on access to their markets a

comprehensive program of preventive management of all chemicals. WEEE directives for other

countries in the world to develop e-waste management regulations reference, which extended

producer responsibility to be a basic system of some countries e-waste recycling management

legislations, such as in Germany “Act Governing the Sale, Return and Environmentally Sound

Disposal of Electrical and Electronic Equipment ”(ElektroG Act) was developed in March 2005,

“Waste Electrical and Electronic Products Recycling Regulations” was officially implemented on

January 1, 2010 in China. Recycling is reducing electronic waste common measures against

(1989-1990), A. U. J. I. l. L. P. y.: Assessment of the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal, Hackett, David P. [ 34 pages, 291 to 324 ]

environmental pollution, but some scholars through empirical put in electrical and electronic

recycling in considering electronic waste recycling logistics network building and other factors in

the overall environmental impact of electronic products recycling it may not always be on the

environment and health damage is smaller. “Recycling is not as environmental friendly as

expected, especially when it comes to the impact of fossil fuels or respiratory inorganics (winter

smog)”.

Obviously, environmental risk brought by technology updating of electronic paste cannot be

efficiently supervised by these regulations or management measures. The usage of nanopowders

brings the new possible pollution and harm on environment, but currently the relevant

management measure is not yet issued globally. No specific laws that regulate the safety

evaluation of MNs exist” and “nanosciences and nanotechnologies are set to transform the

global industrial landscape, but the debate on how to regulate environmental, health and safety

risks is lagging behind technological innovation” . Although there are already some monitoring

and management for heavy metals such as the Au, Ag, copper, nickel etc. and volatile organic

compounds, it is still difficult to implement in practice. It is because a certain emission

concentrations of the pollutants would also be permitted, sometimes due to beyond of detection

threshold of the instrument. That is to say, the pollutants could still have chance to be lost to

environment in limited concentrations, although there is already some monitoring and

management. From these perspectives, it is very important that the manufacturers of products have

the positive consciousness of environmental protection. The voice of extended producer

responsibility is arising in the legal professions, but the essence of extended producer

responsibility is still the traditional environmental management concepts of “the terminal

treatment”. So the efforts are far from enough to control some new environmental risks arising

from the update of electronic paste.

Conclusions

In short, humans have entered the era of risk after the industrial revolution. The

risk prevention principle has become a global consensus. How to strengthen the new technology

Y. Barba-Gutie´rrez et al. / Resources, Conservation and Recycling 52 (2008) 481-495. Takayuki Anzai　et al. /Safety Evaluation for Nanomaterials 15(2),17–29,2012. Falkner, Robert and Jaspers, Nico (2012) Regulating nanotechnologies: risk, uncertainty and the global governance gap. Global environmental politics, 12 (1). pp. 30-55.

risk assessment and management due to progressed society brought by rapid technology changes

is a hot issue that every country must address. For the field of electronic paste, the application of

new technology promotes the performance of electronic components, but also brings some new

and even greater environmental risks to some extent. The relevant laws, regulations and risk-

control technology still lag behind technological development. Therefore, how to effectively

strengthen the assessment and management of the environmental impacts at the same time

technical development of electronic pastes. To achieve sustainable development for social and the

environment, more attention should be attracted for all of us. Meanwhile, the theory this paper

stated that emerging technology is likely to lead to more environmental risks is also suitable for

many other products. That is to say sending alarm signals is just the first step to solve the problem,

because this is not a single problem appeared to one or a series of products and the whole industry

society have to face this social issue.

AcknowledgementThis paper is financially supported by National Natural Science Foundation of China (NSFC)

and ……(No. 51261008)Literature cited