Definition
Wire bonding is the oldest and still most common first-level interconnect in semiconductor packaging. It joins the bond pads on a silicon die to the leads or substrate of the package using fine wires, typically 15-50 microns thick, made of gold, copper, or aluminum. The wire is welded in place by a combination of heat, pressure, and ultrasonic energy in a low-temperature solid-state process, with no solder required.
Ball bonding versus wedge bonding
The two dominant techniques are ball bonding and wedge bonding. In ball bonding, an electronic flame-off forms a small ball on the wire tip, which is pressed onto the die pad to make the first bond; the wire then loops to a lead where a stitched second bond is formed. Wedge bonding instead presses the bare wire flat against each pad with ultrasonic energy, producing a lower loop profile favored in RF and power devices. Gold ball bonding historically dominated, but copper wire has grown rapidly because it is cheaper and has lower electrical resistance.
Where it fits in mining hardware
Many of the support chips on a mining control board and PSU, plus a number of lower-pin-count packages, rely on wire bonding. The high-pin-count hashing ASICs themselves, however, generally use area-array flip-chip or BGA attachment instead, because wire bonding cannot deliver the thousands of low-inductance connections those parts demand. Understanding which interconnect a component uses helps a repair technician judge what is rework-friendly and what is not.
For the alternative area-array approach, see Flip Chip, and for the broader packaging picture see Chip Package.
In Simple Terms
Wire bonding is the oldest and still most common first-level interconnect in semiconductor packaging. It joins the bond pads on a silicon die to the…