FRANKLIN, MA – Speedline Technologies and Agilent Technologies have found that positional accuracy of a paste deposit relative to the pad is the critical element in ensuring good fine-pitch, lead-free assemblies, and is even more critical for some formulations than others.

 A report on the three-month investigation to understand and quantify variables in a lead-free manufacturing process will be presented at SMTA International in Chicago in September.

Solder volume can be managed across the supplier base with printer variables and stencil design. As with lead-bearing solder pastes, using enclosed print heads will present advantages such as better aperture fill, however it is not the determining factor for a high quality process. The atmosphere and profile of the reflow oven contribute substantially to the overall quality of the lead-free assembly.
 
The goal of this first design of experiments was to understand the impact of the positional accuracy of the printed solder paste to the component pad, the positional accuracy of the placed component to the component pad, and atmosphere and profile of the reflow process. The experiment used Agilent’s Medalist SJ50 Series II AOI systems.