Workmanship Training and Certification Workmanship training is what converts a written standard into a consistent result, and certification is the evidence that the conversion happened. Neither is complete without a reference sample that shows what the standard means in practice. The subject is often treated as an induction activity, while…

Selective Soldering: Practical Checks for Production Selective soldering applies solder to individual through hole joints with a small nozzle, which lets a board carry parts that cannot survive a wave. The process is local, and every parameter in it is set for one joint rather than for a whole panel.…

Board Storage and Humidity Control Boards and components absorb moisture from the air, and the rate depends on the material and on the environment. Storage control is the practice of keeping that absorption within the limits the process can tolerate. The controls are simple: a defined environment, sealed packaging, a…

PCB Panel Utilization and Material Yield Every board is cut from a panel, and the panel carries more than the boards it yields. Spacing, tooling, edge clearance and the way the array is singulated all consume area, and the difference between the area of the boards and the area of…

Prepreg Resin Content and Flow Control in Lamination Prepreg is woven glass cloth that has been impregnated with a partially cured resin, and the amount of resin it carries is one of the two variables that decide how a multilayer stack behaves during pressing. Resin content and resin flow together…

Solder Paste Jetting Versus Stencil Printing Solder paste can be placed on a board through a stencil or jetted from a nozzle, and the two routes produce deposits by different means. One is a printing process with a tool that touches the board, and the other is a dispensing process…

Copper Peel Strength Testing: Methods and Control Limits Peel strength testing measures how hard it is to pull a strip of copper away from the laminate at a defined angle and speed. It is the standard way to check that the bond between the foil and the resin, and between…

Hand Soldering: Design Rules and Process Limits Automated assembly handles most of the joints on a modern board, but hand soldering still closes the last few per cent: connectors, shields, wire terminations, rework and everything that cannot survive a reflow oven. Those joints are also the ones most likely to…

Flex PCB Stiffener Bonding and Bend Radius Control Stiffeners are bonded onto a flexible circuit so that a connector, a switch or a component landing area behaves like a rigid board in one local region while the rest of the circuit still bends. The bond, the material and the radius…

Double Sided Assembly: Design Rules and Process Limits A double sided assembly is reflowed twice, and the second pass is the one that causes trouble. The parts placed in the first pass are already on the board, and they have to survive a second trip through the oven without falling…