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www.us-tech.com
February, 2018
Eliminating Harmful Airborne Pollutants in Electronics Assembly
By Stefan Meissner, Head of Corporate Communications, ULT AG, and Arne Neiser, Product Manager Wave and Reflow Soldering Systems, SEHO Systems GmbH
ployees, equipment and products. Soldering today comprises a variety of processes, including wave, reflow, dip, hot air, selective, laser, vacuum, and vapor phase soldering. In the production of electronic
A
assemblies, soft soldering is used al- most exclusively. The melting tem- perature of the solder is lower than that of the elements to be joined, e.g. component leads to PCB pads, which falls in the range of 356 to 500° F (180 to 260°C). The molten solder flows between the metal parts to cre- ate a firm, airtight, corrosion-resist- ant, conductive interconnection. Solder alloys are often supplied
in the form of wire, solder bar or sol- der paste. Depending on the particu- lar application, these alloys are com- posed of tin, lead, antimony, silver, and copper. Fluxing agents can be contained in the solder, which include different chemical compositions, such as rosin. Normally, halogen-free flux agents are used to the support the building of proper solder joints.
A Shift Toward Automation Decades ago, soldering was ac-
complished by numerous workers equipped with soldering irons who
ll soldering processes produce airborne pollutants that can have harmful effects on em-
soldered individual assemblies en- tirely by hand. Today, automated sol- dering systems of many different shapes and sizes are used. However, hand soldering at manual work- benches is still found in the majority of assembly production plants. Hand soldering is most often employed for pre-production runs, prototyping, re- work, and repair.
reflow or selective soldering. Which system is used depends on the type and lot size of the product. Many pro- duction lines have multiple systems that are used for different assemblies.
Airborne Pollutants Depending on the application
and requirements of specific compo- nents in an assembly, various solder-
the solder will evaporate, releasing aerosols and particles into the ambi- ent air. Besides spreading unpleasant
odors, these fumes can harm human workers in the area, which can lead to serious medical conditions. Gases are also released from coatings, ad- hesives and substrates during the heating of the assembly. Aldehydes are particularly dangerous sub- stances that emerge from materials that contain colophony — some of which can be carcinogenic. These gases and fumes also
transport sticky aerosols, which build up in the soldering machines or on the products themselves. This leads to in- creased cleaning and maintenance costs, and can impair the operation of the plant. Products can even be cor- roded by the contamination, affecting quality and functionality. In conventional wave soldering
processes, the entire PCB is fluxed. The emerging spray mists from alco- hol-based fluxes and other evapora- tions may lead to explosive, highly- flammable vapor/air mixtures.
Fumes released from a PCB during wave soldering (photo credit: SEHO Systems).
These machines are highly-spe-
cialized systems that can perform unique soldering techniques, such as
ing alloys and flux agents are consid- ered. During soldering, large parts of the flux agent and a small portion of
Legal Regulations Airborne pollutants are classi-
fied according to particle size. This classification is determined primari-
Continued on next page
Manufactured in the U.S.A. since 1966
www.westbond.com
1551 S. Harris Court Anaheim, CA 92806 Tel 714·978·1551 See at ATX / MD&M West, Booth 844
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