Solder Mask Adhesion: 4 Checks After Curing Solder mask adhesion is the bond between the cured coating and the copper or laminate beneath it, and it is asked to survive more than most coatings. It sees flux, cleaning chemistry, thermal cycling and mechanical handling, all after the panel has left…

Etchback Control for Reliable Plated Through Holes Etchback is the deliberate removal of resin from the wall of a drilled hole so that the copper of the inner layers protrudes slightly into the hole. Plating then wraps around that exposed copper, which produces a connection with more contact area than…

Hole Wall Pull-Away: Why Plated Barrels Separate Hole wall pull-away is a separation between the copper of a plated through hole barrel and the resin wall it was plated onto. The gap may be a few micrometres or more than twenty, and it usually appears after a thermal excursion rather…

PCB Statement of Work Data: What the Numbers Say 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 statement of work data gives you a practical…

Flux Acid Value Control: 7 Rules for Consistent Soldering Acid value is a laboratory number that describes how much acidic material is present in a flux, expressed as the amount of alkali needed to neutralise a known weight of it. It is one of the few measurements that predicts how…

Flux Spitting in Wave Soldering: Causes and Controls Flux spitting is the ejection of flux droplets from the applicator that land on areas of the board where they were not intended. The droplets appear as isolated spots, sometimes with a dark ring, and they are usually seen on the top…

Plating Rack Maintenance for PCB Plating Lines: 7 Rules Every panel in an electroplating line is held by a rack or a jig, and that rack is part of the electrical circuit. The current enters through the rack contacts, passes through the panel and leaves at the other end. Any…

Flux Webbing Between Pads: Causes and Removal Steps Flux webbing is a thin film of flux residue that has dried in a stretched sheet between two adjacent pads, usually spanning the gap rather than sitting on either surface. It looks like a membrane and, because it bridges the gap, it…

Component Skewing After Reflow: Causes and Corrections Component skewing is a rotation of a component about its own centre during reflow, so that a part placed accurately ends up sitting at an angle to its pads. On a two terminal chip component the rotation is easy to see; on a…

Microvoids in Plated Copper: Detection and Root Causes A microvoid is a small cavity inside plated copper, typically a few micrometres across and often located where the barrel meets the surface pad or an inner layer connection. It is inside the copper rather than between the copper and the resin,…