标签: moisture

MoisturesensitivecomponentMoisture-sensitiveComponentsRobertRowlandThetopicofmoisture-sensitivecomponentsisratherboringbutveryimportant―andfrequentlymisunderstood.Increasedmoisture-sensitivecomponentuse,suchasthinfine-pitchdevicesandballgridarrays(BGA),hasincreasedconcernforthisfailuremechanism.Whencomponentsareexposedtotheelevatedtemperaturesthatoccurduringreflowsoldering,moisturetrappedinsideplasticsurfacemountdevices(SMD)producesenoughvaporpressuretodamageordestroythedevice.Commonfailuremodesincludeinternalseparation(delamination)oftheplasticfromthedieorlead-frame;wirebonddamage;diedamage;andinternalcracksthatdonotextendtothecomponentsurface.Inextremecases,crackswillextendtothecomponentsurface;inthem……