Soldering fume in electronics manufacturing - damaging effects and solutions for removal
Modern electronics manufacturing is made up by a multiplicity of different separation and joining processes, with the later surely taking the vast majority of production technology. Alongside gluing, welding and laser processes, soldering still holds a primary position in electronic assemblies. However, soldering does not always equal soldering, because there are quite a lot of different soldering technologies. Accordingly, you have to distinguish between automated and manual soldering procedures.
No matter which soldering process you analyse, all of them have one aspect in common: they produce airborne pollutants, which may have a negative impact on employees, plants and products as well.
Soldering procedures in electronics manufacturing
There are a variety of soldering procedures, but not all of them are used in electronics manufacture. Common soldering techniques in assembly production are:
1）Wave soldering or flow soldering
2）Reflow soldering
3）Dip soldering
4）Hot air soldering
5）Selective soldering
6）Laser soldering
7）Vacuum soldering
8）Vapour phase soldering
In the production of electronic assemblies, almost only soft soldering is used. The melting temperature of the solder is lower than the melting temperature of the elements to be joined, e.g. component leads to PCB pads - (approx. 180 to 260 °C). The molten solder flows between the metal parts. The objective is to create a firm, airtight, corrosion-resistant, electrically and thermally conductive interconnection. The solder is mostly designed from alloys in the form of solder wire, solder bar or solder paste. Depending on the scope of application of the final product, these alloys are composed of tin, lead, antimony, silver and/or copper. In the solder, fluxing agents can be contained, which are compiled from different chemical Hand soldering at manual workplaces is still found in the vast majority of assembly production plants. The main application area is for pre-production runs, prototyping and repair.
Released airborne pollutants
Depending on areas of application of the finished assembly and requirements of the components, various soldering alloys and flux agents are considered. During the soldering process, large parts of the flux agent and a small portion of the solder will evaporate. The emerging aerosols and particles could be released into ambient air. This will not only spread unpleasant odours, but these airborne pollutants can lead to serious medical conditions. Particularly dangerous substances are aldehydes, which emerge from materials containing colophony; some of them may be carcinogenic.
In addition, gases are released from coatings, adhesives or substrates during heating of the assembly.
These gases also transport sticky aerosols, which build up in the soldering machines or – even worse – on the products and contaminate them. This leads to increased cleaning and maintenance costs, and the operability of the plant can be impaired. In addition, the manufactured products may even be corroded by the contaminations, which could affect functionality and quality.
In conventional wave soldering processes, the entire printed circuit board is fluxed. The emerging spray mists from alcohol-based flux and other evaporations may lead to explosive, highly flammable vapour/air mixtures.
Differentiation and legal regulations
Airborne pollutants are classified according to particle size. This classification is set primarily by the influence of the emissions on the human organism. Thus, airborne
pollutants are not only differentiated, whether they are brain, nerve or airway damaging. A distinction is made, whether they are inhalable (I-fraction) or alveolar (A-fraction). Pollutants of the A-fraction overcome the so-called lung-blood barrier, which separates air-filled cavities of the pulmonary alveolus from blood in the capillaries.
Therefore, the DIN EN 481 defines statutory limit values. According to technical rules for hazardous substances in various countries, there are limit values and legal regulations that determine the utilization of extraction and filtration technology to meet these regularities.
In order to eliminate developing air pollutants, it is not sufficient to provide for only good ventilation in the manufacturing environment. The use of efficient extraction and filtration technology is mandatory and required by the Employer’s Liability
Insurance Association.
The variety of the available extraction and filtration systems is high. The selection of the appropriate system depends on type and volume of pollution, the use in automated, semi-automated or manual production environments and on mobility as well as flexibility.
State of the art extraction and filtration units achieve such a high cleaning rate for the processing air that the cleaned air can even be re-circulated into the work area.
The competitive pressure in electronics manufacturing is tremendous. Only those who provide high quality products, minimise maintenance costs and rely on healthy employees, will successfully survive in highly competitive markets. Thereby air purification plays a major role.
In the field of electronic assemblies manufacture, this means more than ventilation and vacuum cleaning. Besides removing dirt and unpleasant odours, it is mainly about removing airborne hazardous substances, which may have a drastic impact on humans, machinery and products. Effectively running extraction and filtration units help entire enterprises to maintain competitiveness.
Modern electronics manufacturing is made up by a multiplicity of different separation and joining processes, with the later surely taking the vast majority of production technology. Alongside gluing, welding and laser processes, soldering still holds a primary position in electronic assemblies. However, soldering does not always equal soldering, because there are quite a lot of different soldering technologies. Accordingly, you have to distinguish between automated and manual soldering procedures.
No matter which soldering process you analyse, all of them have one aspect in common: they produce airborne pollutants, which may have a negative impact on employees, plants and products as well.
Soldering procedures in electronics manufacturing
There are a variety of soldering procedures, but not all of them are used in electronics manufacture. Common soldering techniques in assembly production are:
1）Wave soldering or flow soldering
2）Reflow soldering
3）Dip soldering
4）Hot air soldering
5）Selective soldering
6）Laser soldering
7）Vacuum soldering
8）Vapour phase soldering
In the production of electronic assemblies, almost only soft soldering is used. The melting temperature of the solder is lower than the melting temperature of the elements to be joined, e.g. component leads to PCB pads - (approx. 180 to 260 °C). The molten solder flows between the metal parts. The objective is to create a firm, airtight, corrosion-resistant, electrically and thermally conductive interconnection. The solder is mostly designed from alloys in the form of solder wire, solder bar or solder paste. Depending on the scope of application of the final product, these alloys are composed of tin, lead, antimony, silver and/or copper. In the solder, fluxing agents can be contained, which are compiled from different chemical Hand soldering at manual workplaces is still found in the vast majority of assembly production plants. The main application area is for pre-production runs, prototyping and repair.
Released airborne pollutants
Depending on areas of application of the finished assembly and requirements of the components, various soldering alloys and flux agents are considered. During the soldering process, large parts of the flux agent and a small portion of the solder will evaporate. The emerging aerosols and particles could be released into ambient air. This will not only spread unpleasant odours, but these airborne pollutants can lead to serious medical conditions. Particularly dangerous substances are aldehydes, which emerge from materials containing colophony; some of them may be carcinogenic.
In addition, gases are released from coatings, adhesives or substrates during heating of the assembly.
These gases also transport sticky aerosols, which build up in the soldering machines or – even worse – on the products and contaminate them. This leads to increased cleaning and maintenance costs, and the operability of the plant can be impaired. In addition, the manufactured products may even be corroded by the contaminations, which could affect functionality and quality.
In conventional wave soldering processes, the entire printed circuit board is fluxed. The emerging spray mists from alcohol-based flux and other evaporations may lead to explosive, highly flammable vapour/air mixtures.
Differentiation and legal regulations
Airborne pollutants are classified according to particle size. This classification is set primarily by the influence of the emissions on the human organism. Thus, airborne
pollutants are not only differentiated, whether they are brain, nerve or airway damaging. A distinction is made, whether they are inhalable (I-fraction) or alveolar (A-fraction). Pollutants of the A-fraction overcome the so-called lung-blood barrier, which separates air-filled cavities of the pulmonary alveolus from blood in the capillaries.
Therefore, the DIN EN 481 defines statutory limit values. According to technical rules for hazardous substances in various countries, there are limit values and legal regulations that determine the utilization of extraction and filtration technology to meet these regularities.
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