Aoi Programming: Preparation, Placement and Process Control An automated optical inspection system finds what it has been taught to find, and it reports everything it is unsure about as a call for review. The engineering effort in AOI is therefore not in the camera but in the program: how the…

Continuous Improvement in Electronics Assembly Continuous improvement is a habit rather than a project. In electronics assembly it shows up as a steady reduction in defect rates, changeover times and rework hours that comes from many small changes rather than one large programme. The mechanism is unglamorous: measure something, find…

Scratch Prevention and Handling in PCB Fabrication A scratch is a cosmetic defect that becomes a functional one when it crosses a conductor. It is produced by handling rather than by a machine, and it is the defect that a shop is least able to prevent with an equipment purchase…

Feeder and Nozzle Inventory Control Placement quality depends on a great deal of engineering, and it can be destroyed in an afternoon by a worn nozzle or a feeder that has drifted out of calibration. Feeders and nozzles are the least glamorous assets on an SMT line and the ones…

Thermal Interface Material Application in Electronics A heatsink only works if heat can reach it. The interface between a component and its heatsink is a thin layer of air unless something fills it, and that air is a poor conductor. A thermal interface material replaces the air with a medium…

Laminate and Prepreg Storage Control Prepreg and laminate are the raw materials that decide whether a multilayer board survives the soldering process, and they are also the easiest materials in the factory to store badly. Prepreg arrives partly cured and continues to react slowly at room temperature, absorbing moisture from…

Placement Program: Pick and Place Programming and Optimization A pick and place machine is only as good as its program. The hardware can place a component to within tens of micrometres, but the machine will only do so if it knows where the board is, which nozzle carries the part…

Peelable Mask for Temporary Protection on PCB Panels A peelable mask is a temporary coating that is applied over areas that must not be soldered, plated or coated, and then removed by hand after the operation is complete. It is a form of temporary protection that is used to protect…

Solder Paste Qualification for a New Line Choosing a solder paste is often treated as a purchasing decision, and qualifying it is often treated as a formality. In practice the paste sets the print window, the residue chemistry and the reflow behaviour of the whole line, and a change late…

Panelization Strategy for Odd Shaped Boards A rectangular board of moderate size panelizes easily. A circular board, an L shaped board or a long narrow strip does not, because there is no straight edge to run along the conveyor and no obvious place to put the tabs. Panelization for odd…