Filling through holes and blind microvias with copper using reverse pulse plating and insoluble anodes

Roelfs, Bernd; Dambrowsky, Nina; Erben, Christof; Kenny, S. T.

doi:10.1108/03056121211250632

Cited by 28 publications

(26 citation statements)

References 1 publication

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“…As we move to the next generation of these pillar bumps (from 90 μm pillar diameter/40 μm pillar height to 10 μm pillar diameter/50 μm pillar height-see Fig. 1a), the aspect ratio of the bumps keeps getting higher which is a problem since electroplating at this scale is limited to a maximum aspect ratio of ≈2:1 22 . Thus, fabricating these structures is out of the capabilities of the current electroplating processes used to make the pillar bump arrays.…”

Section: Introductionmentioning

confidence: 99%

A novel microscale selective laser sintering (μ-SLS) process for the fabrication of microelectronic parts

et al. 2019

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One of the biggest challenges in microscale additive manufacturing is the production of three-dimensional, microscale metal parts with a high enough throughput to be relevant for commercial applications. This paper presents a new microscale additive manufacturing process called microscale selective laser sintering (μ-SLS) that can produce true 3D metal parts with sub-5 μm resolution and a throughput of greater than 60 mm 3 /hour. In μ-SLS, a layer of metal nanoparticle ink is first coated onto a substrate using a slot die coating system. The ink is then dried to produce a uniform nanoparticle layer. Next, the substrate is precisely positioned under an optical subsystem using a set of coarse and fine nanopositioning stages. In the optical subsystem, laser light that has been patterned using a digital micromirror array is used to heat and sinter the nanoparticles into the desired patterns. This set of steps is then repeated to build up each layer of the 3D part in the μ-SLS system. Overall, this new technology offers the potential to overcome many of the current limitations in microscale additive manufacturing of metals and become an important process in microelectronics packaging applications.

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Section: Introductionmentioning

confidence: 99%

A novel microscale selective laser sintering (μ-SLS) process for the fabrication of microelectronic parts

et al. 2019

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“…Such boards would be especially desirable in the mobile phone market which uses Cu-filled thorough hole vias (THVs) of low aspect ratio of 4:1, as these currently require high fabrication costs because of special filling chemistry and plating waveforms (Roelfs, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Such interconnects would enable a) increased electrical and thermal conductivity, over the partially plated vias and b) multilayer fabrication with less thermally intensive bonding operations, increasing board lifetime and reducing fabrication costs. Such boards would be especially desirable in the mobile phone market which employs Cu filled THVs, of low aspect ratio of 4:1, as these currently require high fabrication costs due to special filling chemistry and plating waveforms (Roelfs et al, 2013).…”

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confidence: 99%

Morphology and acoustic artefacts of copper deposits electroplated using megasonic assisted agitation

Jones¹,

Flynn²,

Desmulliez³

et al. 2016

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Purpose ± A study of the influence of megasonic (MS) assisted agitation on Printed Circuit Boards (PCBs) electroplated using copper electrolyte solutions, to improve plating efficiencies through enhanced ion transportation. Design/methodology/approach-The impact of MS assisted agitation on topographical properties of the electroplated surfaces studied, through a Design of Experiments (DOE), by measuring surface roughness, characterised by values of the parameter Ra as measured by white light phase shifting interferometry and high resolution scanning electron microscopy. Findings ± An increase of Ra from 400 nm to 760 nm measured after plating, for an increase to acoustic power from 45 W to 450 W. Roughening increase due to micro-bubble cavitation energy, supported through direct imaging of the cavitation. Current thieving effect by the MS transducer induced low-currents, leading to large Cu grain frosting reducing the board quality. Current thieving was negated in plating trials through specific placement of transducer. Wavy electroplated surfaces, due to surface acoustic waves, also observed reducing the uniformity of the deposit. Research limitations/implications ± The formation of unstable transient cavitation and variation of the topology of the copper surface are unwanted phenomena. Further plating studies using megasonic agitation are needed, along with fundamental simulations, to determine how the effects can be reduced or prevented. Practical implications ± Identify manufacturing settings required for high-quality MS assisted plating and promote areas for further investigation, leading to the development of an MS plating manufacturing technique. Originality/value ± Quantification of the topographical changes to a PCB surface in response to megasonic agitation and evidence for deposited copper artefacts due to acoustic effects.

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“…Two multilayer structures are combined together to form a system after curing prepreg for lamination, whereas the cured conductive paste is used to generate electric conduction for these two multilayer structures. Such design can prevent the extremely high aspect ratio of through holes to result in the defective copper deposit around through holes (Wang et al , 2014; Roelfs et al , 2012; Kisiel et al , 2007).…”

Section: Methodsmentioning

confidence: 99%

Pre-curing investigation of filling conductive paste in prepreg to interconnect two multilayer structures of backboard for press-fit application

Wang

Yang

Chen

et al. 2016

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Purpose The purpose of this paper is to form high density interconnection (HDI) of backboard for press-fit applications with the pre-curing conditions of conductive paste. The best condition of pre-curing conductive paste should be found to obtain good electrical and physical performance of the conductive paste and avoid the simultaneous curing behavior of prepreg. Design/methodology/approach A novel structure of backboard was designed by using the connection of conductive paste-filled through holes to connect two multilayers. Pre-curing conditions of conductive paste were investigated to find their effects on resistance, bond strength and volume shrinkage. The reliability of pre-curing conductive paste was also analyzed. Findings Pre-curing conditions led to a great influence on the resistance, bond strength and volume shrinkage of the conductive paste. The best condition of pre-curing conductive paste was chosen as the low curing temperature of 60°C and a curing time of 30 min. Cured conductive paste exhibited square resistance of 4.205 mΩ/□ and bonding strength of 22.86 N. The as-obtained pre-curing condition could improve the reliability of conductive paste. Pre-curing process of conductive paste at extremely low temperature to interconnect two multilayer structures improved the density interconnection of backboard for press-fit applications. Originality/value The use of HDI of backboard could lead to good assembly for high-speed signal transmission of electronic products with press-fitting components. The connection of pre-curing conductive paste for multilayers could have important function for improving the application for communication backboard.

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Filling through holes and blind microvias with copper using reverse pulse plating and insoluble anodes

Cited by 28 publications

References 1 publication

A novel microscale selective laser sintering (μ-SLS) process for the fabrication of microelectronic parts

A novel microscale selective laser sintering (μ-SLS) process for the fabrication of microelectronic parts

Morphology and acoustic artefacts of copper deposits electroplated using megasonic assisted agitation

Pre-curing investigation of filling conductive paste in prepreg to interconnect two multilayer structures of backboard for press-fit application

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