Contact bonding technique

These methods are usable only when the adhesive retains some tack when dry. The only difference between the two techniques is that in pressure-sensitive bonding only one adherend is coated versus both surfaces in contact bonding. In both techniques, joint assembly consists of permitting the adhesive coating to dry completely, then aligning the parts and pressing them together to form the bond. 

The as-grown samples were investigated by optical microscopy and room temperature PL measurements. 300 x 300 gm square diode were defined by chlorine-based RIE. Electron beam deposited Pd/Au (20/200 nm) and Al/Au (30/300 nm) were used as p-GaN and n-GaN contacts, respectively. For packaging, the wafer was diced into discrete dies for attachment to submounts. Conventional die-bonding and wire-bonding techniques were then apphed, and the individual LEDs were packaged into conventional epoxy-encapsulated lamps. The electrical and luminescence characteristics of the diode were... 

Initial stmcture equUibration, wherein bad or close contacts are reheved this may be done with constraints on bonds, eg, to simplify the process (the premise of the SHAKE technique). 

Aluminum, the most common material used for contacts, is easy to use, has low resistivity, and reduces surface Si02 to form interfacial metal-oxide bonds that promote adhesion to the substrate. However, as designs reach submicrometer dimensions, aluminum, Al, has been found to be a poor choice for metallization of contacts and via holes. Al has relatively poor step coverage, which is nonuniform layer thickness when deposited over right-angled geometric features. This leads to keyhole void formation when spaces between features are smaller than 0.7 p.m. New collimated sputtering techniques can extend the lower limit of Al use to 0.5-p.m appHcations. 

Ceramics cannot be bolted or riveted the contact stresses would cause brittle failure. Instead, ceramic components are bonded to other ceramic or metal parts by techniques which avoid or minimise stress concentrations. 

---