Structural design guideline to minimize extreme low-k delamination potential in 40nm flip-chip packages

Lai, Yi‐Shao; Shih, Meng-Kai; Lee, Chang-Chi; Wang, Tong Hong

doi:10.1016/j.microrel.2012.05.007

Cited by 11 publications

(1 citation statement)

References 8 publications

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“…4,5 Another reliability issue is delamination of the low-k dialectic layer. 6 Because of the high modulus of copper pillars, which transmits more mechanical stress to the die during the bonding process, and high thermal stress that results from CTE mismatch between the die and substrate, the thermo-mechanical stress causes severe damage to the inherently weak low-k dielectric layer, resulting in delamination of the layer. Because the mechanical properties of porous, low-k materials decrease with lower dielectric constants, 7 this problem will become more severe in the future when materials with a lower dielectric constant are employed.…”

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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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