Isola PCB Materials: Dk, Df and Which Laminate to Choose Material Choice Sets the Ceiling on Performance Once a board is designed, the laminate it is built on is fixed for the life of the product. That makes the substrate decision unusually consequential: it sets the dielectric constant that the…

Copper Foil PCB: ED and RA Foil, Thickness and Cost The Layer That Carries Everything Every printed circuit board is a stack of dielectric and copper foil. The dielectric provides the insulation and the mechanical base, and the copper provides the conductor: the signal path, the power distribution network, the…

PCB Via Structures: Through, Blind, Buried and Microvia The Smallest Feature With the Largest Influence Holes are the most basic structure on a printed circuit board and, in a high density design, the one that constrains everything else. A hole either connects layers or it does not; it either accepts…

PCB Eye Diagrams: Reading Signal Quality at Speed One Picture That Summarises the Whole Channel An eye diagram compresses everything that happens to a high speed signal into a single image. Thousands of individual bit periods are overlaid on top of each other, synchronised to the clock, and what emerges…

TDR Impedance Testing: How PCB Impedance Gets Verified Impedance Control Is Only Real If It Is Measured A controlled impedance specification is a target, not an outcome. A stack-up drawing says that a trace on layer three will present fifty ohms, and that claim rests on a chain of assumptions:…

Hot Air Solder Levelling: How HASL Works and When to Use It The Finish Most Boards Still Use Surface finishes have multiplied over the years, but the oldest of them is still the most widely used. Hot air solder levelling has been applied to circuit boards for decades, and it…

PCB Manufacturing Tolerances: What to Specify and What It Costs Every Dimension Has a Range A printed circuit board is a manufactured object, so no dimension on it is exact. Tolerance is the range within which each dimension is allowed to vary, and a board that meets its functional requirement…

DBC Substrate: Direct Bonded Copper for Power Modules When Metal Core and FR-4 Both Run Out Power density in modern converters has risen to the point where the two familiar answers stop working. FR-4 insulates well but conducts heat at a few tenths of a watt per metre kelvin, and…

Immersion Silver PCB: Flat Pads, Lead Free and What It Costs A Finish Chosen for Flatness Surface finish is the part of the board specification that gets the least attention and causes a surprising share of assembly problems. It has three jobs: keep the copper solderable until the board is…

PCB Hidden Solder Ball Under BGA: Trapped Under the Package 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 hidden solder ball under BGA from the perspective of…