Selective Deposition of Conductive Particles for Anisotropic Conductive Adhesive Interconnects

Huynh, Van Long; Aasmundtveit, Knut E.; Nguyen, Hoang-Vu

doi:10.1109/estc55720.2022.9939469

Cited by 3 publications

(3 citation statements)

References 16 publications

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“…The deposition process is described in the previous work. [31] In short, a droplet of particles dispersed in de-ionized (DI) water was dragged over the surface of a PDMS carrier by a moving stage. When the droplet swept over the surface of the trap area, capillary force led to deposition of particles inside individual traps (Figure 1b).…”

Section: Methodsmentioning

confidence: 99%

Enabling Low Pressure, Low Temperature, and Particle Control for Anisotropic Conductive Adhesives

Huynh,

Aasmundtveit,

Nguyen

2024

Adv Materials Technologies

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Anisotropic conductive adhesives (ACAs) are the preferred interconnection technology for applications that employ large dies, flexible substrates, and ultra fine‐pitch interconnects. Conventional ACAs require relatively high bonding pressures and temperatures, and ultra fine‐pitch applications challenge the trade‐off between low interconnect resistance and risk of short circuits. This study introduces an ACA‐like interconnection technology that addresses these limitations, allowing for low‐pressure, low‐temperature assembly processes with enhanced particle control at the interconnects. Conductive particles are deposited onto a patterned carrier and subsequently transferred to electrical pads using either non‐conductive film or Ag sintering. The Ag sintering process is performed at a low temperature (140 °C) and low bonding pressure (1 N for a 10 × 10 mm2 chip). The capability of controlling the position and number of conductive particles within individual interconnects is demonstrated. This presents possibilities for achieving ultra‐fine pitch interconnects with negligible risk of short circuits, without compromising electrical resistance. It is demonstrated that interconnect resistance can be tuned by varying the number of conductive particles (achieving a resistance as low as 33 mΩ with 25 particles per interconnect). This approach is applicable to scenarios where the bonding force and temperature must remain low due to the nature of substrate materials.

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Section: Methodsmentioning

confidence: 99%

Enabling Low Pressure, Low Temperature, and Particle Control for Anisotropic Conductive Adhesives

Huynh,

Aasmundtveit,

Nguyen

2024

Adv Materials Technologies

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“…The experimental setup for depositing conductive particles has been described in previous work [14]. In short, a droplet (20 µl) of colloidal Ag-coated polymer spheres (40 µm in diameter, Ag thickness of 120 nm, supplied by Conpart AS, Norway) in 0.01 wt.% polyethylene glycol tert-octylphenyl ether (Triton X-100, VWR Chemicals) was injected between the moving PDMS carrier and the fixed glass slide (Fig 1b).…”

Section: Particle Deposition On Pdms Carriermentioning

confidence: 99%

“…On one hand, a shallower depth results in particles being unable to stay in the traps (capillary forces smaller than droplet drag force). On the other hand, increasing the trap depth leads to the formation of particle clusters being deposited in a single trap [14]. Additionally, the trap depth defines the thickness of silver ink to be used in the ink deposition process since the deposited particles on the PDMS carrier come into contact with the ink.…”

Section: A Fabrication Of Pdms Carrier and Particle Depositionmentioning

confidence: 99%

Flip-Chip Interconnects Based on Single Metal-Coated Polymer Spheres

Huynh,

Aasmundtveit,

Nguyen

2024

IMAPSource Proceedings

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In microelectronics packaging, minimizing thermomechanical stresses is crucial to achieve high reliability. This paper presents a novel approach for flip-chip interconnects, utilizing individual metal-coated polymer spheres at a low bonding temperature. The method involves selectively depositing individual conductive particles onto a polydimethylsiloxane (PDMS) carrier and then transferring the particles to electrical pads on substrate using Ag sintering followed by die placement and introducing underfill material. The deposition process achieved a high yield of 98.8% on the PDMS carrier, while the transferring process resulted in well-defined ink dots with a yield of 96.2%. The sintered Ag formed good bonds between the particles and electrical pads, leading to moderate interconnect resistance (as low as 0.57 Ω). This work has demonstrated the feasibility of interconnects based on a single metal-coated polymer sphere with low thermomechanical stress induced, thanks to the low bonding temperature (140 °C) and pressure (0.1 MPa) as well as the mechanical compliance of polymer particles.

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