Mcmaster: Created page with "= Introduction = 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 s..."

2019-03-05T00:15:16Z

Created page with "= Introduction = 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 s..."

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= Introduction =

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)

[[File:zoidberg_ball_bond_01_neo20x_cropped.jpg|300 px]]

or this (focal plane on ball)

[[File:zoidberg_ball_bond_02_neo20x_cropped.jpg|300 px]]

Angled SEM image of ball bond (Samsung 16-mbit DRAM). Image copyright 1998-2009 Smithsonian Institution; used by [[archive>smithsonian|permission]].

[[File:smithsonian_ball_bond.jpg|300 px]]

= Second bond =

Test bonds on gold package pad (from AZ's training)

[[File:bonding_second-bond.jpg|500 px]]

= Capillary cleaning =

SPT Capillary Unplugging Wires (CUW) tool
* http://www.epakelectronics.com/spt_capillaries_cuw.htm
* http://www.epakelectronics.com/pdf/spt/SPT-CAP-CUW-Brochure.pdf
* Haven't tested
* My capillary is something like 1.6 mil => 40 um => CUW-35 reccomended
* Note 1 mil wire => 25 um

https://patents.google.com/patent/US20020096187A1/en
* Pretty boring
* Says poke it with a wire, ultrasonically clean it, and maybe sand the tip
* Duh..this is what I tried before looking. Although I don't have a fine enough wire on hand

A few sources hint at methanol as the preferred cleaning agent

https://www.ebay.com/itm/CROSSHAIR-WIRE-FINE-TUNGSTEN-WIRE-FOR-SCOPES-AND-TRANSITS-0125mm-0005/321070292094?hash=item4ac147dc7e:g:v-wAAMXQ2UVQ9N2j
* CROSSHAIR WIRE FINE TUNGSTEN WIRE FOR SCOPES AND TRANSITS .0125mm/.0005"
* 0.0005 and 0.0015
* 3' lengths
* Smaller than I wanted, but eh lets give it a try since its so inexpensive

Bonding ball - Revision history

Mcmaster: Created page with "= Introduction = 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 s..."