Second Side Reflow and Support Fixture Design Guide On a double sided assembly the second reflow pass is the one that causes trouble, because the components placed on the first side are now on the underside and held only by the surface tension of their own solder joints. Second side…

Selective Soldering: Design Rules and Process Limits Selective soldering fills through holes one joint at a time with a small nozzle, which makes it the natural choice for mixed technology boards where wave soldering would damage the surface mount side or where only a few through-hole parts remain. The process…

ESD Control in Electronics Assembly Electrostatic discharge is invisible, intermittent and capable of reducing the life of a component without producing any immediate measurable change. A board damaged by a discharge may pass every test on the line and fail in the field months later, which makes the cost of…

Flux-Cored Solder Wire Selection for Hand Soldering Hand soldering is judged by the joint it produces, and the wire used to make it is as much a process material as the paste used in reflow. A flux-cored solder wire combines the alloy and the flux in one consumable, and the…

Assembly Drawing and BOM Accuracy An assembly runs on two documents: the bill of materials, which says what to place, and the assembly drawing, which says where and in what orientation. When those documents disagree with the board layout, the line stops, and when they disagree with each other but…

Tape and Reel Packaging Requirements for Automated Assembly A component that is packed badly cannot be placed well. Tape and reel packaging is a mechanical interface between the component supplier and the placement machine, and it determines whether the part arrives at the pickup position reliably or intermittently. Most packaging…

Conductive Adhesive Assembly in Electronics Manufacturing Conductive adhesive joins and conducts with a polymer rather than with a molten alloy. It is chosen when the temperature required for soldering is the problem: a component that cannot survive reflow, a substrate that is not solderable, a heat sensitive structure or a…

Conformal Coating Application Control Conformal coating protects a finished assembly from moisture, contamination and, in some products, from mechanical abrasion. It only does so where it is present, and the failure modes of coating are almost all coverage failures: a thin edge, a shadowed area between components, a connector that…

PCB Traceability Records: Writing It Down 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 traceability records from the perspective of a PCBA factory floor, covering recording traceability…

PCB Traceability Cost: What It Adds Up To 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…