Card Edge Connector and Gold Finger Design A card edge connector is a board that plugs into a socket, and the contact area is the gold finger. It is a wearing surface, a current path and a mechanical datum at the same time, and it is usually defined by a…

Underfill Dispensing for Flip Chip and CSP Packages A flip chip joint is a very short column of solder between a silicon die and a substrate, and the two materials expand at very different rates. Every thermal cycle loads that column in shear, and after enough cycles a crack starts…

Parylene Coating for High Reliability PCB Assemblies Most protective coatings are applied as a liquid, and every liquid shares the same limitations: it runs, it pools, it leaves thin spots over sharp edges and it cannot reach into the shadow behind a tall component. Parylene is different because it is…

Mixed Alloy Soldering and Step Reflow Windows Two soldering alloys in the same assembly is a common requirement: a lead free main assembly with a temperature sensitive part, or a mixed alloy legacy board. The problem is that the second alloy must melt without disturbing the first. Why Mixed Alloys…

PCB Copper Foil Grain Structure and Etch Behaviour Copper foil is the starting point of every trace on a printed circuit board, and the way it is made decides how it etches, how it adheres and how it behaves at high frequency. Two foils of the same weight and the…

PCB Particle Count Monitoring: Counting What Floats Modern electronics depend on boards that are assembled correctly the first time. Every product – a phone, a charger, a medical instrument or an industrial controller – relies on thousands of solder joints that must conduct current for years. This article explains PCB…

PCB Cleanroom Discipline: Keeping the Room Clean 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 cleanroom discipline from the perspective of a PCBA factory floor, covering working…

PCB Shift Rotation Planning: Who Works When Buyers and engineers often focus on the finished product and forget the production line behind it. In practice, most field failures can be traced back to process decisions made during assembly. Understanding PCB shift rotation planning gives you a practical advantage when you…

Gas Sensor Interface Circuit Design A gas sensor turns a chemical concentration into a small electrical change, and the circuit around it has to do two jobs at once: drive the element under stable conditions and read a signal that moves slowly. Most field failures in these designs come from…

Flow Meter Interface Circuit Design A flow meter converts a volume or mass rate into something an instrument can read: a train of pulses, a current, a frequency or a digital value on a bus. The interface circuit is chosen by that output type and by the environment, and the…