Anisotropic Conductive Film (ACF) bonding: effect of interfaces on contact resistance

Nghiem, Giang M.; Aasmundtveit, Knut E.; Kristiansen, Helge; Bazilchuk, Molly

doi:10.1109/estc.2018.8546414

Cited by 8 publications

(8 citation statements)

References 10 publications

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“…In particular, the bonding pressure determines the surface contact and deformation of the conductive particles. Nghiem et al has shown that there is an optimal deformation percentage of Ni/Au polymer balls (3µm), in the range of 35-75% between bump and pad for achieving a stable and reliable ACF [16]. For lower deformations, trapping a thin layer of adhesive between the particle and contacts may occur, strongly increasing the contact resistance.…”

Section: Concentration Size and Deformation Of Cpsmentioning

confidence: 99%

Conductive Particles in Anisotropic Conductive Films

Goyanes

2022

PSPRJ

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Anisotropic Conductive Films (ACFs) are the major products used for fine-pitch interconnection technology in electronic packaging because of their low incidence in electrical interconnection issues such as high contact resistance and open/short-circuit failure. ACF are conductive adhesives composed of a suitable binder and electrically Conductive Particles (CP). These CP can be selected from a variety of materials to meet specific applications or requirements. In this Mini Review we describe the different types of conductive particles that can be used in ACF, the advantages and disadvantages of each type, as well as other relevant issues such as particle size, concentration, and capture rate. This work could serve as a guide for any group that is interested in research on ACFs.

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Section: Concentration Size and Deformation Of Cpsmentioning

confidence: 99%

Conductive Particles in Anisotropic Conductive Films

Goyanes

2022

PSPRJ

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“…Anisotropic conductive film (ACF) is a widely used electronic component, consisting of conductive particles and adhesive polymer resins [18][19][20][21]. By subjecting the ACF to specific temperature and pressure conditions [22], the conductive particles within the ACF are compressed vertically (in the Z-axis direction), facilitating an electrical conduction pathway [23]. Simultaneously, there is no in-plane contact between these conductive particles (X-axis and Y-axis directions), ensuring insulation [24].…”

Section: Introductionmentioning

confidence: 99%

Size Effects of Au/Ni-Coated Polymer Particles on the Electrical Performance of Anisotropic Conductive Adhesive Films under Flexible Mechanical Conditions

Fang,

Wang,

et al. 2024

Materials

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In soft electronics, anisotropic conductive adhesive films (ACFs) are the trending interconnecting approach due to their substantial softness and superior bondability to flexible substrates. However, low bonding pressure (≤1 MPa) and fine-pitch interconnections of ACFs become challenging while being extended in advanced device developments such as wafer-level packaging and three-dimensional multi-layer integrated circuit board assembly. To overcome these difficulties, we studied two types of ACFs with distinct conductive filler sizes (ACF-1: ~20 μm and ACF-2: ~5 μm). We demonstrated a low-pressure thermo-compression bonding technique and investigated the size effect of conductive particles on ACF’s mechanical properties in a customized testing device, which consists of flexible printing circuits and Flex on Flex assemblies. A consistency of low interconnection resistance (<1 Ω) after mechanical stress (cycling bending test up to 600 cycles) verifies the assembly’s outstanding electrical reliability and mechanical stability and thus validates the great effectiveness of the ACF bonding technique. Additionally, in numerical studies using the finite element method, we developed a generic model to disclose the size effect of Au/Ni-coated polymer fillers in ACF on device reliability under mechanical stress. For the first time, we confirmed that ACFs with smaller filler particles are more prone to coating fracture, leading to deteriorated electrical interconnections, and are more likely to peel off from substrate electrode pads resulting in electrical faults. This study provides guides for ACF design and manufacturing and would facilitate the advancement of soft wearable electronic devices.

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“…Different fine-pitch interconnect bonding methods are contrasted, as shown in Figure 1(c) (Liu et al , 2021a), involving SLID bonding, anisotropic conductive film (ACF) bonding and metal/dielectric hybrid bonding (Lu et al , 2019; Tsai et al , 2019; Tang et al , 2018; Guangming et al , 2017; Kim et al , 2013; Nghiem et al , 2018). SLID faced reliability problems of underfill and solders, with intermetallic compounds appearing in the bonding process, for instance.…”

Section: Introductionmentioning

confidence: 99%

Recent progress on bumpless Cu/SiO₂ hybrid bonding for 3D heterogeneous integration

Kang

Niu

et al. 2022

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Purpose Bumpless Cu/SiO2 hybrid bonding, which this paper aims to, is a key technology of three-dimensional (3D) high-density integration to promote the integrated circuits industry’s continuous development, which achieves the stacks of chips vertically connected via through-silicon via. Surface-activated bonding (SAB) and thermal-compression bonding (TCB) are used, but both have some shortcomings. The SAB method is overdemanding in the bonding environment, and the TCB method requires a high temperature to remove copper oxide from surfaces, which increases the thermal budget and grossly damages the fine-pitch device. Design/methodology/approach In this review, methods to prevent and remove copper oxidation in the whole bonding process for a lower bonding temperature, such as wet treatment, plasma surface activation, nanotwinned copper and the metal passivation layer, are investigated. Findings The cooperative bonding method combining wet treatment and plasma activation shows outstanding technological superiority without the high cost and additional necessity of copper passivation in manufacture. Cu/SiO2 hybrid bonding has great potential to effectively enhance the integration density in future 3D packaging for artificial intelligence, the internet of things and other high-density chips. Originality/value To achieve heterogeneous bonding at a lower temperature, the SAB method, chemical treatment and the plasma-assisted bonding method (based on TCB) are used, and surface-enhanced measurements such as nanotwinned copper and the metal passivation layer are also applied to prevent surface copper oxide.

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Anisotropic Conductive Film (ACF) bonding: effect of interfaces on contact resistance

Cited by 8 publications

References 10 publications

Conductive Particles in Anisotropic Conductive Films

Conductive Particles in Anisotropic Conductive Films

Size Effects of Au/Ni-Coated Polymer Particles on the Electrical Performance of Anisotropic Conductive Adhesive Films under Flexible Mechanical Conditions

Recent progress on bumpless Cu/SiO₂ hybrid bonding for 3D heterogeneous integration

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Anisotropic Conductive Film (ACF) bonding: effect of interfaces on contact resistance

Cited by 8 publications

References 10 publications

Conductive Particles in Anisotropic Conductive Films

Conductive Particles in Anisotropic Conductive Films

Size Effects of Au/Ni-Coated Polymer Particles on the Electrical Performance of Anisotropic Conductive Adhesive Films under Flexible Mechanical Conditions

Recent progress on bumpless Cu/SiO2 hybrid bonding for 3D heterogeneous integration

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Product

Resources

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Recent progress on bumpless Cu/SiO₂ hybrid bonding for 3D heterogeneous integration