Technical Library | 2003-04-18 12:05:57.0
The popular tin (Sn) rich lead free solders are causing severe corrosion to many of the materials used in today's Wave Solder systems. Users are experiencing higher maintenance frequency and reduced life of wave solder machine components. This paper describes the effects of Sn rich solders in contact with various materials and discusses alternate methods to alleviate this problem.
Technical Library | 2023-11-14 19:33:57.0
Wave soldering is an established technology and is commonly used where large unit volumes occur with low product variety. However, if a wave soldering machine is getting old or if technological changes or new PCB designs limits its manufacturing capabilities, consideration should be given to whether selective soldering would be a better choice. Anyone who deals with soldering through-hole and surface mount mixed-technology printed circuit assemblies will quickly discover that a selective soldering machine is not only less expensive that wave soldering, but selective soldering also offers the opportunity to meet customer requirements with significantly more flexibility. One such company is Thomas Preuhs GmbH. Located in Geislingen, Germany, Thomas Preuhs GmbH manufactures a variety of electronic assemblies for solar and HVAC data systems, automotive and white goods products as well as electric drive systems.
Technical Library | 2021-11-16 22:17:27.0
Ultrasonics, coupled with an aqueous detergent process that cleans at below 43ºC, may be best suited for fine-pitch SMT screens and stencils. Aqueous detergents clean more effectively than solvents, with little or no environmental impact. Because of the environmental concerns driving today's technology decisions, the once simple decision of selecting a stencil cleaning process is now clouded with different chemicals, different cleaning machines and various types of solder paste, all with specific environmental, health and safety related issues and regulations.
Technical Library | 2017-05-17 22:33:43.0
The selective soldering application requires a combination of performance attributes that traditional liquid fluxes designed for wave soldering applications cannot fulfill. First, the flux deposition on the board needs to be carefully controlled. Proper fine tuning of the flux physicochemical characteristics combined with a process optimization are mandatory to strike the right balance between solderability and reliability. However, localization of the flux residue through the drop jet process is not enough to guarantee the expected performance level. The flux needs to be designed to minimize the impact of unavoidable spreading and splashing events.From this perspective a fundamental understanding of the relationships between formulation and reliability is critical. In this application, thermal history of the flux residues (from room temperature to solder liquidus) is a key performance driver. Finally, it is necessary to conduct statistically designed experiments on industrial selective soldering machines in order to map the relationships between flux characteristics and selective process friendliness.
