Copper Balance and Warpage in Multilayer PCB Lamination Warpage in a multilayer board is usually blamed on the press, and the press is often innocent. The board warps because the stresses built into it during lamination are unbalanced, and the most common source of imbalance is the distribution of copper.…

Metal Core PCB versus FR4: Thermal and Cost Comparison When a circuit generates more heat than an ordinary laminate can remove, the first question is whether the problem is really thermal or whether it is a matter of layout. A metal core PCB solves a specific problem: it spreads heat…

Gold Fingers and Edge Connector Design A gold finger is a row of equally spaced rectangular pads along the edge of a board, plated with gold and left free of solder mask. The board slides into a slot connector and the pads make contact with the spring contacts inside it,…

PCB Prototype Order: Every Field You Must Specify A PCB prototype order is a specification, and the fabricator will build exactly what the specification says rather than what the designer intended. Every field that is left blank is filled in with a default, and the default is chosen for cost…

PCB Panelization: Why Boards Are Combined A small board is difficult to manufacture and even more difficult to assemble. It does not fit the fixture, it does not feed through the placement machine reliably, and it wastes panel area if it is produced one at a time. PCB panelization is…

Metal Core PCB and Ceramic Substrates: Thermal Paths Compared When a design has to remove heat from a component, two substrate families are usually considered: a metal core construction, in which an aluminium or copper base acts as the heat spreader, and a ceramic substrate, in which the material itself…

Crystal Oscillator Layout for MCU Clock Circuits A microcontroller is a complete small computer on one chip: processor, memory, timers and counters, and input and output interfaces all fabricated together. What makes it run is the clock. Digital logic advances one step for each clock edge it receives, so the…

LDI in PCB Fabrication: Laser Direct Imaging for Fine Lines For decades, printed circuit patterns were transferred the way photographs were printed: a transparent film carried the image, and light passed through it onto a photosensitive coating. That approach served the industry well, but it has a physical ceiling. As…

Solder Defects Behind Most Board Failures When a prototype behaves erratically, the search usually starts in the software and works back toward the design. In practice a large share of hardware failures originate at the solder joint, and a joint that is marginal produces symptoms that look exactly like a…

SMT Inspection Methods: Visual, AOI, X-Ray and ICT Surface mount assembly has many steps, and any one of them can introduce a defect. Paste printing, placement, reflow and handling each have their own failure modes, and the defects they produce look different and hide in different places. That is why…