In recent years, several new technologies have been released in an effort to address the challenges of cleaning high reliability board assemblies. Along with chemical and thermal energies, the mechanical energies delivered through spray technologies are equally critical to the entire cleaning process.
Most board assemblers strive to optimize their cleaning process to provide the best cleaning performance over a broad range of board assemblies. This paper presents the results from a designed experiment on fluid dynamics across multiple types of spray technologies and the overall impact to cleaning performance and process flexibility.
Assemblers surveyed report that cleaning misprinted circuit assemblies is a production gap that has not been adequately addressed. Traditionally, the industry has used stencil cleaning agents and equipment to address this rework need. One of the benefits of cleaning misprinted assemblies with the stencil cleaning process is the ability to collect and filter wet solder paste.
Assemblers surveyed report that cleaning misprinted circuit assemblies is a production gap that has not been adequately addressed. Traditionally, the industry has used stencil cleaning agents and equipment to address this rework need. One of the benefits of cleaning misprinted assemblies with the stencil cleaning process is the ability to collect and filter wet solder paste. The major short coming of cleaning misprints within stencil cleaning processes is the inability to remove B-side reflow flux residues from both the surface and under bottom termination components.
As the electronics industry moves toward the implementation of Pb-free soldering, the impact on the assembly process must be considered. One process that is often over looked is the cleaning of assembled printed circuit boards. How will the introduction of lead free material impact the cleaning process? A number of studies have proven the poorer wetting of SAC 305 alloys and many of the other Pb-free alloys as contrasted to Sn/Pb during the soldering process.
Moore’s Law infers that the number of transistors on a chip doubles approximately every two years. Consistent with Moore’s Law, high reliability electronic devices build faster processing speed and memory capacity using increasing smaller platforms.
The use of high velocity, heated air to remove residual water has become the predominant method for drying printed circuit boards in the in-line aqueous cleaning process. As lead-free circuit boards become more complex and component spacing decreases, the effectiveness of direct blow-off drying is greatly diminished.
No-clean pastes have specific physical properties, which directly impact industry standard electronic assembly cleaning processes.