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X-ray picture of inadequate solder joints. Rework is practiced in many kinds of manufacturing when defective products are found. [2] For electronics, defects may include: Poor solder joints because of faulty assembly or thermal cycling. Solder bridges—unwanted drops of solder that connect points that should be isolated from each other.
The joint's tensile strength is dependent on the filler metal used; in electrical soldering little tensile strength comes from the added solder which is why it is advised that wires be twisted or folded together before soldering to provide some mechanical strength for a joint. A good solder joint produces an electrically conductive, water- and ...
Anything with a base unit with provision to maintain a stable temperature, pump air in either direction, etc., is often called a "station" (preceded by rework, soldering, desoldering, hot air); one, or sometimes more, tools may be connected to a station, e.g., a rework station may accommodate a soldering iron and hot air head.
Solder joint dimensions in SMT quickly become much smaller as advances are made toward ultra-fine pitch technology. The reliability of solder joints becomes more of a concern as less and less solder is allowed for each joint. Voiding is a fault commonly associated with solder joints, especially when reflowing a solder paste in the SMT application.
Used as wire for hand soldering rework; compatible with SnCu 0.7, SnAg 3 Cu 0.5, SnAg 3.9 Cu 0.6, and similar alloys. Used as solder spheres for BGA/CSP components. Used for step soldering and die attachment in high power devices. Established history in the industry. [51] Widely used. Strong lead-free joints.
Rosin used as flux for soldering A flux pen used for electronics rework Multicore solder containing flux Wire freshly coated with solder, held above molten rosin flux. In metallurgy, a flux is a chemical reducing agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time.
The subscripts 1 refer to the component, 2 and b refer to the board, and s refer to the solder joint. The shear stress (∆τ) is then calculated by dividing this calculated force by the effective solder joint area. Strain energy is computed using the shear strain range and shear stress from the following relationship:
Soldered joints can fail in many ways including electromigration and the formation of brittle intermetallic layers. Some failures show only at extreme joint temperatures, hindering troubleshooting. Thermal expansion mismatch between the printed circuit board material and component packaging strains the part-to-board bonds.
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