The most prominent difference between lead-free and regular solder materials is the temperature that is needed for them to form a proper intermetallic bond. This factor creates a major difference in their utility from their reliability, usage, repair and rework standpoint. The common tin-lead alloys like Sn60 Pb40 or Sn63 Pb37 melt around 361° F (183° C). On the other hand, the more popular lead-free solder alloys like the SAC305 (Sn96.5 Ag3.0 Cu0.5) has a melting point around 428° F (220°).
The above difference in melting temperatures generates many changes in the overall soldering processes. In case of lead-free solders, the substrates, circuit boards, flux – everything will have to be chosen in accordance with their ability to withstand higher temperatures in mind. This issue however doesn’t arise with regular tin-lead solders that have traditionally been in use across various industries and are, by default, compatible with most manufacturing processes.
Lead-free, rosin-core solder alloys will definitely create a visually different looking bond than regular solders. While traditional lead-based solders have a shiny finish, their lead-free counterparts create a duller looking bond. Lead-free solder is also more prone to formation of tin whiskers and bridges. Regular solder is also more eutectic than lead-free solder alloys. The soldering process window with lead-free solder is also shorter as compared to its counterparts, owing to the higher melting temperature of the material. However, despite these factors, lead-free solder is able to create a strong and reliable intermetallic bond between surfaces, just like regular solder.
Health and safety
The most obvious difference between regular and lead-free rosin core solder is, of course, the lead content in the alloy. Lead can build up toxins in the body due to repeated exposures over time, and its extensive use in the electronics industry is causing a state of alarm. It has been found that small lead deposits from electronic waste dumps can seep into the ecosystem, the soil and water reservoirs and make them toxic. Lead-free solders have been developed specifically to resolve this hazard. Lead-free solders are a lot more conducive towards health and environment safety than regular solders.
The difference between lead-free, rosin-core, and regular solder alloys are many and you may have to adopt various process changes to incorporate the former into your manufacturing operations. But the benefits of lead-free solder alloys, particularly its compliance with the RoHS directive and its safety parameters make it the obvious choice for you!
About The Company
Alpha Assembly Solutions Inc. is the global leader in the development, manufacturing and sales of innovative specialty materials used in a wide range of industry segments, including electronics assembly, power electronics, die attach, LED lighting, photovoltaics, semiconductor packaging, automotive and others. Since its founding in 1872, Alpha has been committed to developing and manufacturing the highest quality specialty materials.