Boundary Scan: 5 Steps That Lift Test Coverage Boundary scan is a test method that uses the shift register built into a digital device to drive and read the pins around it. Instead of pressing a probe onto a net, the tester shifts a pattern through the chain and compares…

Finished Thickness: 6 Rules for PCB Tolerance Finished thickness is the dimension a board has after every fabrication step is complete, and it is the value that a connector, a card guide or an enclosure will actually see. It is not the laminate thickness ordered, and it is not the…

Filter Cartridge Control: 5 Rules for Plating Baths Filter cartridge selection and change practice decide whether a plating bath deposits clean metal or transfers its contamination onto every panel. The filter is the only component on the line that removes particles continuously, and a cartridge that is too coarse, too…

Orange Peel: 6 Causes in Solder Mask Finish Orange peel is the fine, dimpled texture that sometimes appears on a cured solder mask, named because the surface resembles the skin of a citrus fruit. It is a cosmetic defect in most cases, but it is also a signal that the…

Ion Chromatography: 6 Rules for Flux Residue Ion chromatography is a laboratory method that separates and identifies the individual ionic species left on a board after assembly, rather than reporting a single combined number. It answers the question that a conductivity test cannot: not how much residue is present, but…

Caul Plate Care: 5 Rules for the Press Cycle The caul plate is the flat, rigid plate that sits above and below the book in a multilayer press, and it is what transfers the press force into a flat panel. Its flatness, thickness and surface condition decide whether the stack…

Solder Mask Pre-Cure: 5 Checks Before Exposure Solder mask pre-cure is the drying step between printing and exposure, and it decides whether the pattern that leaves the developer matches the artwork on the film. The printed ink carries solvent that has to leave the film before the mask is imaged,…

Surface Mount Adhesive: 6 Rules for Cure and Dots Surface mount adhesive is the material that holds bottom side components in place before wave soldering, and it is the only thing keeping them there when the board passes over the molten wave. It is dispensed as small dots between the…

Desmear Neutralizer: 5 Checks After Permanganate The desmear neutralizer is the tank that cleans up after the permanganate step. Permanganate attacks resin and removes smear from a drilled hole, and in doing so it leaves manganese dioxide on the hole wall and on the copper surfaces. That residue is dark,…

Palladium Catalyst: 5 Control Points in PTH Plating The palladium catalyst is the step that makes a drilled hole plateable. After desmear and a micro-etch, the panel passes through a palladium catalyst that seeds the dielectric and copper surfaces with catalytic sites, and those sites are what allow the electroless…