Bonding Capillaries Bonding Evolution 2018 by SPT - Small Precision Tools

More catalogs by SPT - Small Precision Tools | Bonding Capillaries Bonding Evolution 2018 | 41 pages | 2018-02-19

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Page 16 of Bonding Capillaries Bonding Evolution 2018

basic capillary design rules as the semiconductor industry braced itself for the transition from gold to copper the copper wire conversion is relatively a tougher process to define as compared to gold wire bonding with challenges both on the ball bond and stitch bond the problem the customer may face varies depending on the bond pad metallization structure and the substrate or lead frame surface condition one of the basic principles to achieve an optimized wire bonding process is through proper capillary design selection the synergy of different process variables coming from the wire e.g gold and copper substrate or lead frame based metallization bond pad metallization and wire bonder are influential to the final geometrical design of the capillary the proper selection of the copper wire bare or coated and capillary type are critical to resolve wire bonding issues like excessive aluminium splashed out short tail or fish tail which are inherent problems related to copper wire bonding a proper design of experiment doe needs to be conducted not only involving the base settings but also considering auxiliary parameters such as scrub function and force/power profiling some high-end wire bonder platforms may have the feature to utilize segmented parameter profiling for specific bonding location of interest the capillary selection process for gold and copper starts with the determination of the following information defined by customers’ device and package design configuration bond pad pitch bpp –is defined as the center distance between two adjacent bond pads specifically for ultra fine pitch application the bpp dictates the design of tip diameter t bottleneck angle bna and chamfer angle ca bpp bond pad opening bpo is defined as the unpassivated area of the bond pad where the actual ball bonds are ultrasonically welded bpo bpp back to content 16