Experimental Research On Process Parameter Optimization For Selective Wave Soldering

With the rapid development of modern electronic information technology, the various types of integrated circuit chip packaging are also emerging, and the packaging density is increasing, which all greatly drive the electronic products to the way of the multifunction, high-performance, high reliability and low cost. Therefore, the electronic components are not completely chip-type, and the low cost advantage of the pin-through-hole (PTH) assembly technology promotes the plug-in through-hole components are still widely used on many occasions. But the PCBA component assemble is more and more density, more and more components can not be wave soldering. Selective soldering is a new soldering concept in assembly technology, which is developed for satisfying the developing requirement of PTH components based on conventional wave soldering process, its technology can act as a substitute to wave soldering to achieve optimal soldering quality by optimizing the processing parameters of single solder joint. Selective soldering normally consists of the flux dispensing module, pre-heating module and selective soldering set. In selective soldering process, the soldering location, soldering temperature and soldering time can be debugged and defined by computer program, and it can automatically make selective flux dispensing, pre-heating and selective soldering according to the scheduling. As a newly introduced technology, the selective wave soldering with advanced, highly complex and intelligent features has undergone great changes in terms of technology and maintenance. Therefore, it is extremely necessary to research on selective soldering process and find the right processing parameters on reducing production costs and improving the soldering quality.In this dissertation, we will optimize the process parameters effecting on the quality of solder joint by using the method of combining process analysis with DOE and hypothesis testing to determine the main technical parameters of effecting the selective wave soldering quality, will find out the major effecting factor and optimize the setting of flux spraying, preheating temperature, soldering temperature, soldering time and nozzle selection.The experiment shows the major effecting factor is soldering time and nozzle selection. When the main selective soldering process parameters were set for: flux spraying parameter is optimal (the speed of linear spraying is 15mm/s,70% of spraying volume and the time of points spraying is set for 1s,70% of spray volume), the top preheating temperature is 100℃, Tin wave temperature is 290℃and the soldering time is set for 1～4s (according to actual of PCB design and the type of parts) and properly soldering nozzle, the selective wave soldering can meet requirements of IPC-A-610, the quality of solder joint will be significantly improved, and solder joints defects rate can be controlled below 1% of the target.