Analysis Method of Tool Topography Change and Identification of Wear Indicators for Heavy Copper Wire Wedge Bonding (bibtex)
by , , , , , ,
Abstract:
Wire bonding is the most common technology for connecting electronic components. Due to their efficiency bond interconnections made of copper wire are used for example in the aerospace and medical technology as well as in the fields of renewable energies. One of the main cost factors in the manufacturing process is the consumables like bonding tools. The technological transition to copper as wire material causes significant wear on the millimeter large effective contact area of the bonding tool. This wear leads to a loss by a factor of 30 of the number of reliable interconnections which can be produced by a single tool. To reduce setting-up time in the production and minimizing costs, an enlarged bonding tool lifetime is desirable. Consequently a better understanding of wear and recognition of wear pattern is required. Therefore, the paper presents an analyzing method of the tool topography change of a heavy wire bonding tool by using a confocal microscope. Furthermore, the paper discusses the identification of the main wear indicators by the help of the named topography change for different bond parameters, like ultrasonic power and tool geometry. Reference topography has been carried out by choosing typical parameters of the production line. To judge whether the quality requirement of the bond connections made by a single tool cannot be fulfilled shear test of the source bond have been carried out after a defined number of produced bond connections. Main steps of analysis: (I)Topography of the tool surface is sampled after a defined number of bonds by means of a confocal microscope to detect the wear progress.(II)The recorded data is filtered using Matlab. So, measurement errors can be eliminated and the topography can be overlaid more easy to identify differences between diverse tools or differences in wear stages of the same tool.(III)The subsequent discretization of the topography into sub volumes allows to (IV)describe the loss of volume depending on the position in the groove. Thereby, intermediate status of wear of one tool can be used to obtain a persistent description of the topography change over the number of produced bonds by interpolating the confocal data. Afterwards the persistent change of the groove flank has been analyzed for the named test series to identify the main wear indicators and their effect on shear forces. All worn tools show dominant areas for volume loss especially for plastic deformation and accordingly abrasion. These wear mechanism can be referred to the change of main parts of the groove geometry like the rounding of the front and back radius. The most volume loss was identified in the upper part of the tool flanks or rather at the transition from the groove flank to the front or back radius. Furthermore the observation of the center of the groove flank shows just a little change in volume. All in all, the identification of the wear indicators will be discussed with the objective of increasing the tool lifetime by optimizing the tool geometry without losses in bond quality and reliability.
Reference:
Eichwald, P.; Sextro, W.; Althoff, S.; Eacock, F.; Unger, A.; Meyer, T.; Guth, K.: Analysis Method of Tool Topography Change and Identification of Wear Indicators for Heavy Copper Wire Wedge Bonding. Proceedings of the 47th International Symposium on Microelectronics, 2014.
Bibtex Entry:
@INPROCEEDINGS{Eichwald2014,
  howpublished = {Conference Proceedings},
  author = {Paul Eichwald AND Walter Sextro AND Simon Althoff AND Florian Eacock
	AND Andreas Unger AND Tobias Meyer AND Karsten Guth},
  title = {Analysis Method of Tool Topography Change and Identification of Wear
	Indicators for Heavy Copper Wire Wedge Bonding},
  booktitle = {Proceedings of the 47th International Symposium on Microelectronics},
  year = {2014},
  pages = {856-861},
  abstract = {Wire bonding is the most common technology for connecting electronic
	components. Due to their efficiency bond interconnections made of
	copper wire are used for example in the aerospace and medical technology
	as well as in the fields of renewable energies. One of the main cost
	factors in the manufacturing process is the consumables like bonding
	tools. The technological transition to copper as wire material causes
	significant wear on the millimeter large effective contact area of
	the bonding tool. This wear leads to a loss by a factor of 30 of
	the number of reliable interconnections which can be produced by
	a single tool. To reduce setting-up time in the production and minimizing
	costs, an enlarged bonding tool lifetime is desirable. Consequently
	a better understanding of wear and recognition of wear pattern is
	required. Therefore, the paper presents an analyzing method of the
	tool topography change of a heavy wire bonding tool by using a confocal
	microscope. Furthermore, the paper discusses the identification of
	the main wear indicators by the help of the named topography change
	for different bond parameters, like ultrasonic power and tool geometry.
	Reference topography has been carried out by choosing typical parameters
	of the production line. To judge whether the quality requirement
	of the bond connections made by a single tool cannot be fulfilled
	shear test of the source bond have been carried out after a defined
	number of produced bond connections. Main steps of analysis: (I)Topography
	of the tool surface is sampled after a defined number of bonds by
	means of a confocal microscope to detect the wear progress.(II)The
	recorded data is filtered using Matlab. So, measurement errors can
	be eliminated and the topography can be overlaid more easy to identify
	differences between diverse tools or differences in wear stages of
	the same tool.(III)The subsequent discretization of the topography
	into sub volumes allows to (IV)describe the loss of volume depending
	on the position in the groove. Thereby, intermediate status of wear
	of one tool can be used to obtain a persistent description of the
	topography change over the number of produced bonds by interpolating
	the confocal data. Afterwards the persistent change of the groove
	flank has been analyzed for the named test series to identify the
	main wear indicators and their effect on shear forces. All worn tools
	show dominant areas for volume loss especially for plastic deformation
	and accordingly abrasion. These wear mechanism can be referred to
	the change of main parts of the groove geometry like the rounding
	of the front and back radius. The most volume loss was identified
	in the upper part of the tool flanks or rather at the transition
	from the groove flank to the front or back radius. Furthermore the
	observation of the center of the groove flank shows just a little
	change in volume. All in all, the identification of the wear indicators
	will be discussed with the objective of increasing the tool lifetime
	by optimizing the tool geometry without losses in bond quality and
	reliability.},
  doi = {10.4071/isom-THP34},
  keywords = {wedge/wedge bonding, copper wire , tool wear}
}
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