Here are the answers to commonly asked questions. Learn what you need to order Solder paste from us.
SAC is an acronym for tin (Sn), silver (Ag) and copper (Cu) containing alloys.
Lead is a toxic metal that is known to cause damage to organs through prolonged exposure. Previously, lead and lead-containing chemicals found in plumbing, gasoline or paint has led to increased blood levels of lead in humans. Lead has been prohibited for several years. Currently, the primary concern is from groundwater leaching of lead-containing solder in electronic products that are disposed of in landfills.”
Lead-free solders have a melting point greater than 215 °C. Therefore, components and PC board materials need to withstand higher soldering temperatures. Lead-free solders exhibit poorer wettability than standard tin-lead solders so defects may increase. When using wave soldering equipment, fluxes must be designed to function at higher reflow temperatures. Higher reflow temperatures result in higher energy usage and costs. Both components and boards must be lead-free in order to be classified as lead-free. Leaded solders have stronger joints than lead-free solders so lead-free solders may require additional rework.”
There are several lead-free solders on the market but SAC (tin-silver-copper) alloys are the commonly used in the electronics industry with SAC305 (Sn96.5/Ag3.0/Cu0.5) being the standard alloy. SAC405 (Sn95.5/Ag4.0/Cu0.5) and SAC105 (Sn98.5/Ag1.0/Cu0.5) are other SAC options. Sn/Ag alloys available are Sn96.5/Ag3.5 and Sn95/Ag5. Qualitek offers Sn/Cu alloy, Sn99.3/Cu0.7 and Sn100e (Sn/Cu/Co). See lead-free alloy chart.”
RoHs is the acronym for Restriction of Hazardous Substances. RoHS, also known as Directive 2011/65/EC, originated in the European Union and restricts the use of specific hazardous materials found in electrical and electronic products. The Restriction of the Use of Certain Hazardous Substances (RoHS) in Electrical and Electronic Equipment (EEE) Directive (2011/65/EU) was transposed into UK law on January 2, 2013.”
Halogens are covalent compounds, whereas halides are ionic free radicals, e.g., Cl- and Br-. Ionic halides are well known effective activators in solder paste. However, ionic materials in solder paste may be hygroscopic and corrosive, resulting in reduction of solder paste shelf-life. Post-reflow residue may become electrically conductive and may corrode metal surfaces especially in the presence of moisture.”
Halogens are useful in solder paste since they allow solder paste to withstand higher temperatures during lead-free reflow soldering. Halogens also provide a stable source for ionic halide when exposed to high temperatures.”
According to IPC (International Printed Circuit), IEC (International Electrotechnical Commission), JPCA (Japan Printed Circuit Association) JPCA-ES-01-1999 defines criteria and method for “Halogen-Free” as any solder paste that contains < 900 ppm of Br (Bromine) and < 900 ppm Cl (chlorine). The maximum total halogens must be <1500 ppm to be considered Halogen-Free.”
Halogen-Free solder paste formulations may contain bonded halogens where halogen zero paste does not contain any halogen or halides.”
Qualitek has formulated a water soluble solder paste that has shown less voiding using BGA (Ball Grid Array) technology. Our solder paste type we recommend is 787LV solder paste.”
Qualitek offers several no clean formulations for both leaded and lead-free applications. Our 670I solder paste flux classification is REL0 and it has low residue with non-conductive residues. No Clean 670I is a robust Sn/Pb solder paste that is drop-in ready.”
Qualitek offers Sn42/Bi58 alloy that has a melting temperature of 139 °C. This alloy is available in solder paste, bar and solid wire forms.”