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Adding local short description: "Surface-mount packaging that uses an array of solder balls", overriding Wikidata description "type of surface-mount packaging" (Shortdesc helper) |
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===Difficulty of inspection===
Once the package is soldered into place, it is difficult to find soldering faults. [[X-ray]] machines, [[industrial CT scanning]] machines,<ref>"CT Services - Overview." Jesse Garant & Associates. August 17, 2010. {{cite web|url=http://www.jgarantmc.com/ct-services.html |title=Archived copy |accessdate=2010-11-24 |url-status = dead|archiveurl=https://web.archive.org/web/20100923150138/http://www.jgarantmc.com/ct-services.html |archivedate=2010-09-23 }}</ref> special microscopes, and endoscopes to look underneath the soldered package have been developed to overcome this problem. If a BGA is found to be badly soldered, it can be removed in a ''[[rework station]]'', which is a jig fitted with infrared lamp (or hot air), a [[thermocouple]] and a vacuum device for lifting the package. The BGA can be replaced with a new one, or it can be refurbished (or ''reballed'') and re-installed on the circuit board. 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. Very common is [[boundary scan]] testing using an IEEE 1149.1 [[JTAG]] port.
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