Underfill Dispensing in PCB Assembly: Materials, Methods and Control Underfill is one of the few assembly processes that exists purely to compensate for a materials problem. A silicon die and an organic board expand at very different rates when they warm up, and the solder joints between them absorb all…

ESD Protection in PCB Layout: Grounding, Guard Rings and Clamping Electrostatic discharge is a natural phenomenon produced by contact, friction and induction between objects. It builds up over time, reaches voltages in the thousands or tens of thousands, carries very little charge, and lasts only briefly. Those characteristics are exactly…

PCB Silkscreen Design: Line Width, Clearance and Marking Silkscreen is the layer of the design that people read. It identifies the components, marks the orientation of the parts that can be fitted the wrong way, warns about handling restrictions and carries the identifiers that link a board to its documentation.…

PCB Trace Width and Current: How to Size Conductors Sizing a conductor is one of the few calculations in board design that can be done on the back of an envelope, and one of the few that is routinely done badly. The physics is simple: a trace has a cross-sectional…

PCB Board Thickness: Standard Values and Tolerances Board thickness looks like the simplest parameter in a fabrication drawing and it is one of the most frequently misunderstood. A nominal figure such as 1.6 mm describes a finished board, including the copper and the plating, and the laminate that is ordered…

Solder Mask and Paste Mask: Openings, Dams and Stencil Two layers in a circuit board drawing are routinely confused. The solder mask is the permanent coating on the finished board, and the paste mask is a drawing of the openings in the stencil that deposits solder paste during assembly. They…

PCB Reverse Engineering: How the Process Actually Works Reverse engineering a board starts from the finished object and works backwards to a schematic. It is used to document equipment that has no available drawings, to reproduce a board whose manufacturer no longer supports it, and to understand how a competitor…

PCB Warpage: Bow, Twist and Stackup Balance Warpage is the permanent deformation of a board that should be flat. It appears as a bow along one axis, as a twist across the diagonal, or as a local hump over a copper heavy area, and it shows up at the worst…

Plated Slot vs Non-Plated Slot in PCB Design Not every hole in a board is round, and not every elongated opening is meant to carry current. A slot can be metallised so that it connects layers and carries a heavy current, or left as bare laminate so that it only…

High-Performance PCB Design: Team, Skills and Engineering Challenges Once a product is fast enough, the bottleneck in a high-performance PCB design stops being layout skill and becomes organization. A board that has to hold a signal integrity budget, meet an emissions limit, fit a shrinking enclosure, and still be manufacturable…