Lead-Bearing Solder Paste Applications
Posted by Alphaassembly on July 26th, 2017
Solder paste is necessary in the manufacturing of PCBs (printed circuit boards), as it is used to connect the surface mount components to the pads on the PCB. It acts like an adhesive or a glue that ensures surface mount parts are secure on the board. Besides holding the PCB components in place, a good solder paste also ensures an excellent electronic bond between the PCB and its components. Hence, it is typically formulated with conductive materials, like lead and tin. Solder paste is basically powdered metal which usually comes suspended in flux. The paste consistency of the solder serves as a temporary adhesive to hold the components until the solder melts during the soldering process to create a more reliable connection. The paste is typically gray with a putty-like texture.
The composition of solder paste depends upon its application. Lead-bearing solder paste is used in a wide range of applications, such as soldering plastic components to an FR-4 glass epoxy circuit board. For such applications, the solders used are SAC alloys (Sn/Ag/Cu or tin/silver/copper) or eutectic Sn-Pb, which is 64% tin and 37% lead. Most solder pastes are made of tin-lead alloys, but depending upon application, sometimes a third metal may be needed.
Due to the safe environmental laws, lead-free solder paste is required for some applications. However, the alternative to lead-bearing solder paste is not ideal for certain high-reliability applications, such as for aerospace and military equipment, as well as for some medical devices. Hence, lead-bearing solder paste is still widely required and used. Lead-bearing solder paste is also preferred for increased productivity in manufacturing handheld electronic devices like tablets and smartphones, consumer electronic products, and computer motherboards. Lead-bearing solder paste is also used in the manufacture of automotive systems and network servers.
Tin-lead solder paste is formulated to meet the demands of Sn/Pb soldering. Manufacturers and suppliers of lead-bearing solder paste guarantee excellent print volume repeatability to enhance productivity and the aesthetics of the board, while ensuring an easy to clean product. Some lead-bearing solder pastes are formulated to withstand lengthy and hot soak reflow profiles to boost the wetting of a lead-free surface with a tin-lead paste alloy.
About the Author:
Alpha Assembly Solutions Inc. is a premier company engaged in the development and manufacture of high quality electronics assembly materials. Since the year of its inception, way back in 1872, the company has played its role on the frontline of innovation, bringing many first-to-market products to the fore thereby, creating a premier niche for itself in the market.
