Process Audit of a PCB Supplier: What the Floor Shows A process audit of a printed circuit supplier is not a document review. The documents describe an intention, and the audit exists to establish what actually happens: whether the coupons are real, whether the measurements are taken as written, and…

PCB Annular Ring Timing: How Long It Takes Buyers and engineers often focus on the finished product and forget the production line behind it. In practice, most field failures can be traced back to process decisions made during assembly. Understanding PCB annular ring timing gives you a practical advantage when…

Drill Bit Inventory: Managing a Consumable That Fails Silently A drill bit is a consumable that degrades gradually, and its failure mode is a slow change in the hole rather than a sudden break. That is what makes drill bit inventory control a quality function rather than a purchasing one:…

Tool Presetting in the Drill Room: Length, Runout and Records Before a drill bit reaches a spindle it is set into a collet to a defined length. That operation, tool presetting, fixes how far the drill protrudes from the holder and how well it is centred, and those two quantities…

Roller Coating Solder Mask: Thickness and Coverage Control Roller coating applies a liquid photoimageable solder mask to a panel by passing it between rollers, in the same way that a printing press applies ink to paper. The process is fast and it wastes little material, and it deposits a film…

Weibull Analysis for PCB Reliability Data: Reading the Slope A reliability test produces a set of failure times, and reducing them to an average throws away the information that the test was run to obtain. Weibull analysis describes the failures as a distribution with a shape and a scale, and…

Fiber Protrusion on the Hole Wall: Cause, Effect and Detection Fiber protrusion is the condition where glass fibers stand out from the resin at the wall of a drilled hole. The fibers are not removed by drilling or by desmear, and the copper that is plated over them follows their…

PCB Annular Ring Handover: Passing It On Electronics manufacturing has become a discipline of small details. Solder paste volumes, placement accuracy, temperature profiles and inspection limits all add up to the final result. This guide looks at PCB annular ring handover from the perspective of a PCBA factory floor, covering…

Resin Bleed on PCB Surfaces: Causes and Control Resin bleed is a thin film of resin that spreads from the laminate onto the copper surface during drilling, lamination or a thermal process. It is rarely visible without magnification, and it is often present over an area much larger than the…

Hot Air Drying After Cleaning: Water Spots and Residue Cleaning a printed circuit assembly ends with drying, and the drying step decides what the cleaning leaves behind. Water that evaporates from a surface deposits whatever was dissolved in it as a ring of residue in the same place. If the…