Peck Drilling Deep Holes on High Aspect Ratio Boards Peck drilling is a drilling cycle in which the bit advances, retracts partly or fully, and advances again until the hole is complete. It is used for deep holes on thick boards, where a single continuous stroke would leave chips packed…

Solder Mask Tack Dry Control Before Exposure Tack dry is the short bake that follows solder mask printing and precedes exposure, and it is the step that decides whether the coating can be imaged cleanly. Its job is to remove most of the solvent from the film so that it…

Selective Soldering Flux Volume and Deposition Control Flux volume is the quantity of activator and vehicle that reaches a joint before the solder does, and in selective soldering it is the least visible part of the process and the most common cause of a joint that fills badly. Unlike wave…

SPI Measurement Repeatability and Gauge Studies Solder paste inspection produces a number for every pad on a panel, and the value of that number depends entirely on how much of it is measurement and how much is noise. Repeatability is the part of the variation that comes from the machine…

Stencil Separation Speed and Paste Release Control How the Stencil Leaves the Board After the squeegee has pushed paste into the apertures, the stencil has to be pulled away from the board while the paste stays behind. On most printers the board drops away on a support plate or the…

Drill Bit Storage: Crib Control for PCB Tool Condition Drill bit storage is the part of the tool cycle that happens between resharpening and the machine, and it is where a surprising amount of damage occurs. A bit stored badly can arrive at the spindle already dulled or chipped. A…

Adhesion Promoter Control Before Conformal Coating: 5 Rules An adhesion promoter is a thin chemical layer applied between the board surface and the conformal coating. It provides the chemical bridge that the coating cannot form on its own, particularly on solder mask, on metal pads and on moulded parts. It…

Hot Bar Soldering Control for Flex to Board Joints: 6 Rules Hot bar soldering joins a flex tail to a rigid board by pressing a heated thermode onto the overlapping pads and melting the solder between them. The process is used where the joint count is high, the pitch is…

SMT Feeder Cart Setup: Staging for Fast Changeover A feeder cart carries pre loaded feeders to the placement machine so that most of the setup happens away from the line. On a high mix line it is the difference between a changeover that takes twenty minutes and one that takes…

Plating Anode Basket Control: Contact, Area and Loading An anode basket holds the copper that replaces what the tank deposits, and it is usually treated as a container rather than as a process component. The way it is loaded, hung and cleaned decides how evenly the current is distributed across…