Alloyed aluminum wires are generally preferred to pure aluminum wire except in high-current devices because of greater drawing ease to fine sizes and higher pull-test strengths in finished devices. Pure aluminum and 0.5% magnesium-aluminum are most commonly used in sizes larger than 0.004 inch.
All aluminum systems in semiconductor fabrication eliminate the "purple plague" (brittle gold-aluminum intermetallic compound) sometimes associated with pure gold bonding wire. Aluminum is particularly suitable for ultrasonic bonding.
Silicon Aluminum Wire
In order to assure that high quality bonds can be obtained at high production speeds, special controls are used in the manufacture of 1% silicon-aluminum wire. One of the most important characteristics of high grade bonding wire of this type is homogeneity of the alloy system. Homogeneity is given special attention at Coining. Microscopic checks of the alloy structure of finished lots of 1% silicon-aluminum wire are performed routinely. Processing also is carried out under conditions which yield the ultimate in surface cleanliness and smooth finish and permits entirely snag-free de-reeling.
Nearly all heavy aluminum wire (generally diameters more than 0.004 inch/100 microns) for microelectronics is drawn from one of three materials: 5/9's pure aluminum; 4/9's pure aluminum; or 0.5% magnesium/aluminum alloy. Of these three principal types of aluminum wire, 5/9's grade exhibits the greatest variation of properties and is very sensitive to the fabrication time cycle due to its ultra purity. 5/9's, 4/9's and 0.5% Mg/Al each exhibit unique properties which can be used to overcome any unusual bonding conditions that manufacturers may experience. Anticipated mechanical properties for each of the three main types of heavy aluminum wire are noted in Heavy Aluminum Wire Data sheet.
Aluminum ribbon is utilized in many microwave and other electronic applications. 1% silicon/aluminum can be rolled as fine as 0.0005 inch (125 microns) thick and also can be delivered in slit form when ratios exceed the standards for forms. Pure aluminum is available as fine as 0.001 inch (250 microns) and can be provided in slit form when specifications dictate.
Please refer to Data sheets below.