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--- bonding:ball [2015/12/17 22:54] – created azonenberg
+++ bonding:ball [2019/03/05 00:15] (current) – removed mcmaster
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-Thermosonic ball bonding is the most common and cost effective method for general use on modern ICs.
-  - The wire is fed through a ceramic capillary, shaped somewhat like the end of a cheap mechanical pencil (fat cylinder with a thin cylinder on the end)
-  - The tip of the wire is melted by an electric arc (negative electric flame-off or NEFO, the most common process) or hydrogen flame (in older bonders, or highly ESD-sensitive applications) and surface tension forms a ball
-  - The capillary is lowered onto the pad and squishes the ball onto the pad. Ultrasound and heat are used to form a solid connection
-  - The second bond (from the wire to the leadframe) is normally very similar to a wedge bond but has a semi-circular or ring shape as it is formed by the side of the capillary
-====== First bond ======
-Overhead shots typically look like this (Photobit camera sensor, focal plane on pad)
-{{:zoidberg:ball_bond_01_neo20x_cropped.jpg?300}}
-or this (focal plane on ball)
-{{:zoidberg:ball_bond_02_neo20x_cropped.jpg?300}}
-Angled SEM image of ball bond (Samsung 16-mbit DRAM). Image copyright 1998-2009 Smithsonian Institution; used by [[archive>smithsonian|permission]].
-{{:smithsonian:ball_bond.jpg?300}}
-====== Second bond ======
-Test bonds on gold package pad (from AZ's training)
-{{:bonding:second-bond.jpg?500|}}