PM Assembly recognizes three main facets of the surface mount process: Print, Place and Reflow. Each of these steps is equally essential to the success of the final product. For this reason, we focus on each step in the following ways: 

Print- Starting with contract review, we ensure we have the correct revision stencil. If a stencil is needed, we carefully review the checkplot and make necessary revisions for the best quality print. During the print process, each print is carefully inspected, sometimes microscopically, to guard against opens, shorts, and voids. If any problems are encountered, Production has the option to suggest more modifications and a new stencil may be ordered to enhance quality and eliminate rework. In addition solder paste performance is evaluated daily with regard to tack and reflow quality. 

Place- In most cases customer-generated CAD data is used to create the programs for the Assembleon pick-and-place machines but we also have the ability to manualy teach programs if necessary. The two main lines use entirely touchless vision centering for alignment. Every line is equipped with an LCS for handling tray components such as BGA and QFP and every line uses vision to align the program with fiducials. Prior to running a first article, each machine load is inspected part by part against the program. A first article must pass inspection prior to proceeding to production and each board thereafter is subjected to a visual inspection prior to reflow.  

Reflow- Every assembly is different with regard to dimensions, number of layers, ground planes and population, and every solder paste manufacturer has a recommended profile for optimum reflow of the solder paste. For these reason, one oven profile will not perform the same for all assemblies. It is our responsibility to tweak each assembly’s profile to match the solder paste profile as close as possible. To that end we employ the SlimKick 2000 profiler. A minimum of two thermocouples are attached to a sample board surface. After the profile parameters are set in the software, the profiler is sent through the oven with the board to record the surface temperature and the profiler downloads the recorded data to the computer . At that point the software will grade the profile with a Process Window Index (PWI), and make change recommendations to make the profile better. If the grade is not acceptable, the process engineer will make changes to the zone temperatures and/or the conveyor speed and repeat the process.