Chip-to-Chip Direct Interconnections by Using Controlled 
Flow Electroless Ni Plating

Hung, Tai-Ho; Yang, Shi-Yi; Chen, Y. B.; Kao, C. R.

doi:10.1007/s11664-017-5385-0

Cited by 24 publications

(10 citation statements)

References 12 publications

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“…In the previous example, where the values of the parameters correspond to the physical design of [6], we could have neglected the inertial terms and work with the Stokes approximation. In order to validate the algorithm at higher Reynolds number, which may be the case for other plating problems, we keep all parameters given in the end of Section 7.1 but change the Reynolds number to the inverse of ν = 0.01.…”

Section: Numerical Results At Larger Reynolds Numbermentioning

confidence: 99%

“…We have proposed a simplified model which approximates the Electroless process of [6] by replacing the time dependent domain occupied by the reacting chemical by a fixed domain using a transpiration approximation. We have validated the approximation numerically with a finite element method in space and a fully implicit in time approximation.…”

Section: Discussionmentioning

confidence: 99%

“…For instance, in the copper interconnecting process [5] by electroless plating, the thickness of the deposition layer of copper is large enough to risk a connection of the pillars. From an experimental point of view, microfluidic electroless plating is very time consuming [6]. For example, even a sample preparation for investigating an electroless plating process is highly timeconsuming.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of an electroless plating problem

Girault

Pironneau

2021

IMA Journal of Numerical Analysis

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Electroless plating in microfluidic channels is a novel technology at the micrometer scale. As the microchannel depth varies with the flow of the chemicals, care must be taken for the channel not to run dry. Owing to the deposited chemical species the physical domain of the flow changes with time, leading to a free boundary problem. As the motion of the free boundary is small it is modelled by a transpiration approximation. With this simplification, the mathematical model consists of a Navier–Stokes flow and an equation for the concentration of the plating chemical coupled by nonstandard and nonlinear boundary conditions. Existence and uniqueness are proved for the concentration equation, assuming that the flow is given. Numerical analysis is carried out and justifies the proposed numerical schemes and the nonlinear algorithms. The numerical study is performed, in the two-dimensional case, with the finite element method and an implicit Euler time scheme for the coupled problem with the Navier–Stokes flow and the nonlinear concentration equation.

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Section: Numerical Results At Larger Reynolds Numbermentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of an electroless plating problem

Girault

Pironneau

2021

IMA Journal of Numerical Analysis

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“…Furthermore, it has widespread applications in flip-chip bonding pads , and surface finish layers , because the ENIG layer exhibits excellent wear and corrosion resistance. More importantly, electroless plating is a promising way to achieve the vertical interconnection of chips in low temperature and pressureless condition. − Unfortunately, till now, no attention has been given to the electroless plating to produce bumps for micro-LED integration.…”

Section: Introductionmentioning

confidence: 99%

Electroless Deposition of 4 μm High Ni/Au Bumps for 8 μm Pitch Interconnection

Tian

Lin

Pan

et al. 2022

ACS Appl. Electron. Mater.

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We propose that electroless plating is a superb approach to preparing metallic bumps with an ultrafine pitch for the integration of a micro light-emitting diode (micro-LED). Electroless plating does not suffer from lift-off-related issues, which are ubiquitous in thermal evaporation. Besides, it can result in much more uniform bumps than electroplating because the bump height is not affected by the current distribution. This study reports ultrafine pitch Ni/Au bumps fabricated by electroless nickel immersion gold (ENIG) plating. Furthermore, cheap metals iron and nickel are selected to catalyze the electroless nickel process. The results indicate that uniform and consistent Ni/Au bumps can be obtained through the iron sheet and nickel layer method. Besides, no voids and impurities are found inside the bumps, which is beneficial for the following interconnection process. Moreover, the change in Ni bump height values with the electroless plating time is also provided.

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“…However, they found voids or seams at the bonding interface, such that a post-bond annealing step at a temperature of 180 • C was required to remove the seams and strengthen the electroless Cu bonds. 16 Similar to electroless copper plating, Hung et al 17 reported an innovative electroless interconnection technology that used microfluidic technology to join copper pillars with electroless Ni plating. Figure 1 illustrates the scheme proposed for the microfluidic electroless interconnection (MELI) process.…”

mentioning

confidence: 99%

Materials Merging Mechanism of Microfluidic Electroless Interconnection Process

Yang

Hung

et al. 2018

J. Electrochem. Soc.

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A low-temperature, pressureless bonding process, referred to as the microfluidic electroless interconnection process, has been developed for chip-stacking applications, in which electroless Ni plating is employed to bond copper pillars in an attempt to reduce the risk of thermo-mechanical damage during the assembly process. Copper pillar joints with a low standoff height were used to assess the bonding performance of the microfluidic electroless interconnection process on a smaller scale. The results showed that a striking lamellar structure formed in the deposits when electroless Ni solution was fed into a microfluidic platform intermittently, and through this visible structure, the bonding mechanism of the process can be characterized fully. Preliminary results showed that a high level of plating uniformity across the die could be obtained using the microfluidic interconnection process, and that the copper pillars were joined completely by electroless Ni plating without voids or seams. Further, it was found that the process is able to compensate not only for non-uniform copper surfaces, but also for the misalignment of copper pillars, which provides a competitive edge over other bonding methods. In addition, the direct shear test showed that the bond strength of the electroless Ni bonds was quite strong.

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Chip-to-Chip Direct Interconnections by Using Controlled Flow Electroless Ni Plating

Cited by 24 publications

References 12 publications

Analysis of an electroless plating problem

Analysis of an electroless plating problem

Electroless Deposition of 4 μm High Ni/Au Bumps for 8 μm Pitch Interconnection

Materials Merging Mechanism of Microfluidic Electroless Interconnection Process

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