Magnetics Placement and Layout on Switching PCBs Magnetics are the largest components on most power boards and the ones that cause the most layout trouble. An inductor radiates a magnetic field that couples into any loop it can reach, a transformer couples between its own windings, and both dissipate enough…

Stencil Frame Tension and Print Quality A stencil is a mesh held in tension with an aperture pattern imaged into it. The tension is what makes the stencil gasket against the board and snap away cleanly, and it falls with use. How Tension Is Specified The mesh is tensioned at…

Automotive PCB Quality Requirements in Production An automotive customer buys a board that has to work for the life of a vehicle, and the quality system that supports it is part of the product rather than an administrative layer on top. The requirements are written into the drawings, the process…

Hard Gold Plating for Edge Connectors: A Process Guide An edge connector is the part of the board that will be inserted and withdrawn repeatedly, and it is the one place where a surface finish has to survive mechanical wear rather than only a soldering operation. Hard gold plating is…

Measuring Solder Paste Print Quality on the Line Printing is the step where most solder defects are decided. A deposit that is too small will not form a fillet, one that is too large will bridge, and one that smears will shift a component. Measuring print quality turns those outcomes…

SMT Changeover Verification and First Article A changeover is the moment when a line that was producing one product correctly starts producing another. Most of the escapes that follow a changeover are not random; they come from a step that was skipped because the line looked ready, and a verification…

Solder Pot Maintenance and Alloy Contamination A solder pot is a chemical reactor that nobody thinks of as one. Every board that passes over it dissolves a little copper into the bath and carries a little contamination away, and the alloy changes composition slowly over months of production. The change…

Test Strategy Selection for Low Volume PCB Assembly Choosing how to test a low volume assembly is a different problem from choosing how to test a high volume one, because the fixture cost dominates the calculation and because the product may change before the fixture is worn out. A test…

OSP Surface Finish Process Control and Storage Guide OSP, or organic solderability preservative, is a thin organic film that protects clean copper from oxidation without adding any metal to the surface. It is the cheapest of the common finishes, it is simple to apply, and it leaves the flattest possible…

Copper Surface Preparation Before Lamination Multilayer adhesion is created in a few metres of process line. Before the layers are pressed together, the copper surfaces that will form the internal interfaces are cleaned, textured and oxidised so that the resin has something to grip and something to bond to chemically.…