Work in Progress Control on the PCB Floor Work in progress is the material that has been started and not yet finished, and it is the most expensive inventory in a board shop. It has already consumed material, labour and machine time, it occupies space, it hides defects until they…

Shift Handover Process in PCB Production Shift handover is the ten minutes where one crew tells the next what is running, what is waiting and what is wrong, and it is one of the most reliable sources of lost production in a board shop. Jobs are left in an uncertain…

PCB Flatness Measurement Methods and Acceptance Limits Flatness is one of the few board properties that is easy to feel and hard to measure. A panel that rocks on a table is obviously warped, but the same panel measured with a height gauge may pass, because the result depends entirely…

Selective Soldering: Practical Checks for Production Selective soldering makes a small fountain of molten solder and brings it into contact with one joint at a time. The nozzle that forms the fountain is the part that decides whether the process works, because it sets the shape of the flow, the…

Tombstoning And Reflow Thermal Imbalance Tombstoning is the defect in which a small chip component, usually a resistor or a capacitor, stands up on one end during reflow instead of lying flat. One termination is still attached to its pad and the other has been lifted clear, held by the…

Hole Wall Resin Smear And Desmear Drilling a hole in a printed circuit board generates heat, and the heat softens the resin around the hole. As the drill turns and withdraws, the softened resin is smeared across the hole wall like a thin film, and it can cover the copper…

Ultrasonic Cleaning of Assembled Boards and Stencils Ultrasonic cleaning uses sound waves in a liquid bath to remove flux, paste and particulate contamination from an assembly. The waves create microscopic bubbles that collapse against the surface, and the energy released at each collapse lifts contamination from places that brushing cannot…

Moisture Bake: Preparation, Placement and Process Control Laminate absorbs water from the air, and the amount it holds depends on the resin system, the storage conditions and the time since the board was fabricated. When the board is heated to reflow temperature, that water turns to steam, and the steam…

Continuous Improvement in PCB Manufacturing Continuous improvement in a board shop is a habit rather than a programme. The shops that get better every year are not the ones with the largest improvement department; they are the ones where small changes are made, written down and repeated, week after week,…

Capacity Planning: Key Checks Before Release Capacity planning is the work of matching the work available to the work the shop can actually complete, and its central idea is that the shop is limited by one step rather than by its average. That step sets the throughput of the whole…