Every bare PCB starts its assembly journey at the paste printer. Using framed stencils, solder paste is deposited through laser cut apertures onto the exposed copper pads. Stencil thicknesses are typically 4 or 5 mils, and frame sizes can vary. We use no-clean, water-wash flux with either Sn63/Pb37 or SAC305 alloys.
Following paste application, parts are installed by our Samsung/Hanwha Pick and Place. It can hold up to 104 8mm feeders, and over 120 line items when using our custom cut tape holders. Flying vision corrects any offset of passives while upward vision centers BGA, QFP, and other critical components. When coupled with our feeder tracking and parts kitting process, new product setup and job changeover times are kept to a minimum.
Reflow occurs in an 8-zone oven, at the proper temperature profile for the specific alloy and pcb combination. These temperatures are verified with each new product setup by direct thermocouple measurement via a KIC Thermal Profiling device.
A final DI water wash removes flux residue and leaves boards ready for ESD packaging.
First article and final inspections are performed manually under stereo magnifiaction. Any rework needed to meet IPC class acceptability is accomplished using Metcal soldering systems.
Manipulating and tracking data is crucial to the assembly process. Parts kits, labels, component locations, orientations, and reflow profiles all need to be configured perfectly. Our process accomplishes this with speed and precision by automating data entry and using digital work instructions.