Shape-Dependent Transmittable Tangential Force of Wire Bond Tools (bibtex)
by , , , ,
Abstract:
Wire bonding has been an established packaging technology for decades. When introducing copper as wire material for high power applications, adaptations to the bonding process and to machines became necessary. Here, challenges occur due to the stiffer wire material and changing oxide layers on the contact partners. To achieve sufficient process stability, a clean bond area is required, which can only be achieved with high shear stresses in the contact partners surfaces. These necessitate high normal forces to plastically deform the wire and substrate. To achieve such high stresses in the contact area, the bonding tool needs to be able to transmit the needed tangential forces to the top side of the wire. The wire itself performs a shear movement and transmits the force into the contact area to clean the contaminant and oxide layers and to level the desired bond surfaces. The main function of the tool is to transmit these forces. If the bond tool can only transmit low forces in the direction of excitation, the parameter space for a stable bond process is severely restricted. Here, a modeling approach to estimate how well different tool shapes meet the demand of transmitting high tangential forces is presented. The model depends on wire deformation and thus on the ultrasonic softening effect.
Reference:
Althoff, S.; Meyer, T.; Unger, A.; Sextro, W.; Eacock, F.: Shape-Dependent Transmittable Tangential Force of Wire Bond Tools. IEEE 66th Electronic Components and Technology Conference, 2016.
Bibtex Entry:
@INPROCEEDINGS{Althoff2016,
  howpublished = {Conference Proceedings},
  author = {Simon Althoff AND Tobias Meyer AND Andreas Unger AND Walter Sextro
	AND Florian Eacock},
  title = {Shape-Dependent Transmittable Tangential Force of Wire Bond Tools},
  booktitle = {IEEE 66th Electronic Components and Technology Conference},
  year = {2016},
  pages = {2103-2110},
  abstract = {Wire bonding has been an established packaging technology for decades.
	When introducing copper as wire material for high power applications,
	adaptations to the bonding process and to machines became necessary.
	Here, challenges occur due to the stiffer wire material and changing
	oxide layers on the contact partners. To achieve sufficient process
	stability, a clean bond area is required, which can only be achieved
	with high shear stresses in the contact partners surfaces. These
	necessitate high normal forces to plastically deform the wire and
	substrate. To achieve such high stresses in the contact area, the
	bonding tool needs to be able to transmit the needed tangential forces
	to the top side of the wire. The wire itself performs a shear movement
	and transmits the force into the contact area to clean the contaminant
	and oxide layers and to level the desired bond surfaces. The main
	function of the tool is to transmit these forces. If the bond tool
	can only transmit low forces in the direction of excitation, the
	parameter space for a stable bond process is severely restricted.
	Here, a modeling approach to estimate how well different tool shapes
	meet the demand of transmitting high tangential forces is presented.
	The model depends on wire deformation and thus on the ultrasonic
	softening effect.},
  doi = {10.1109/ECTC.2016.234},
  keywords = {finite element simulation, wire bonding, tool geometry}
}
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