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The solder balls can be placed manually or by automated equipment, and are held in place with a tacky flux. [2] A coined solder ball is a solder ball subject to coining, i.e., flattening to a shape resembling that of a coin, to increase contact reliability. [3] Ball grid array, chip-scale package, and flip chip packages generally use solder balls.
Micro ball grid array : Ball spacing less than 1 mm; Thin fine-pitch ball grid array : A square or rectangular array of solder balls on one surface, ball spacing typically 0.5 mm; Land grid array (LGA): An array of bare lands only. Similar to in appearance to QFN, but mating is by spring pins within a socket rather than solder.
Pre-configured solder balls matching the array pattern can be used to reball BGAs when only one or a few need to be reworked. For higher volume and repeated lab work, a stencil-configured vacuum-head pick-up and placement of loose spheres can be used. Due to the cost of visual X-ray BGA inspection, electrical testing is very often used instead.
After soldering, the boards may be washed to remove flux residues and any stray solder balls that could short out closely spaced component leads. Rosin flux is removed with fluorocarbon solvents, high flash point hydrocarbon solvents, or low flash solvents e.g. limonene (derived from orange peels) which require extra rinsing or drying cycles.
Tin-silver-copper (Sn-Ag-Cu, also known as SAC), is a lead-free alloy commonly used for electronic solder.It is the main choice for lead-free surface-mount technology (SMT) assembly in the industry, [1] as it is near eutectic, with adequate thermal fatigue properties, strength, and wettability. [2]
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Reballing involves dismantling, heating the chip until it can be removed from the board, typically with a hot-air gun and vacuum pickup tool, removing the device, removing solder remaining on the device and board, putting new solder balls in place, replacing the original device if there was a poor connection, or using a new one, and heating the ...
Embedded wafer level ball grid array (eWLB) is a packaging technology for integrated circuits. The package interconnects are applied on an artificial wafer made of silicon chips and a casting compound. Principle eWLB. eWLB is a further development of the classical wafer level ball grid array technology (WLB or WLP: wafer level package). The ...