Compliant bumps for adhesive flip chip assembly

Keswick, K.; German, R.L.; Breen, Mark; Nolan, RJ

doi:10.1109/ectc.1994.367659

Cited by 11 publications

(3 citation statements)

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“…When the height of a bump is much lower than other bumps, this can occur due to the lack of contact between the metal bump and the pad on glass substrate. Statistically, as much as 10% variation in thickness was reported in the electroplated metal bumps [18,28]. Plastic deformation of bumps should be sufficient so that the shortest bump can be in contact with the pad of the substrate.…”

Section: Discussionmentioning

confidence: 98%

Highly reliable, fine pitch chip on glass (COG) joints fabricated using Sn/Cu bumps and non-conductive adhesives

Kim

Lee

et al. 2011

Microelectronics Reliability

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Section: Discussionmentioning

confidence: 98%

Highly reliable, fine pitch chip on glass (COG) joints fabricated using Sn/Cu bumps and non-conductive adhesives

Kim

Lee

et al. 2011

Microelectronics Reliability

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“…The compliant-bump structure has been recognized as alternative to replace Au-bump for its excellent reliability [9][10][11] and probing testability [12]. In this work, a 20m pitch COF interconnects with both Au-bumps and sidewallinsulated Au-coated polyimide (PI) compliant-bumps, as shown in Fig.…”

Section: Fig 1 Schematic Of Conductive Particles Bridging For Cof Inmentioning

confidence: 99%

A novel compliant-bump structure for ACA-bonded chip-on-flex (COF) interconnects with ultra-fine pitch

Lin

Chuang

et al. 2009

2009 59th Electronic Components and Technology Conference

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As the growing demand for high-density electronic applications, a novel COF package with sidewall-insulated Au-coated polyimide (PI) compliant-bumps using a doublelayer ACA that can meet the assembly requirement is thus developed for ultra-fine pitch interconnects in this work.The reliability of the ACA-bonded COF package with 20m pitch using both Au-bumps and compliant-bumps is examined, respectively. The double-layer ACA consists of an ACA layer with 2.8m conductive particles in diameter and a NCA layer selected as an interlayer to bind the silicon chip and the flexible substrate together. Bonding accuracy for ultra-fine pitch is inspected through X-ray works after bonding. To evaluate the bonding quality, both the electrical insulation test and the contact resistance measurement of daisy chain with 606 I/Os around the peripheral of chip are performed. Three types of single-layer ACA with 3m, 3.5m and 5m conductive particles in diameter and a single-layer NCA are also adopted to compare their electrical insulation resistance with those by the double-layer ACA, respectively. The compliant-bump bonded samples using the double-layer ACA show their excellent electrical insulation performance even at 5m joint space whereas the Au-bump bonded ones present more than 50% short-circuiting rate no matter what ACA used. It is worthwhile to mention that the compliantbump assembled with 20m pitch COF also passes its reliability evaluation by both the 85°C/85% RH thermal humidity storage test (THST) for 1,000 hours and -55°C ~125°C thermal cycling test (TCT) for 1,000 cycles. The interfaces between silicon chip and substrate for failed samples from the reliability tests are then inspected through the cross-section SEM images.From the results presented, reliable bonding quality and stable contact resistance of the COF package bonded with the compliant-bump structure using the double-layer ACA demonstrate its high potentiality for ultra-fine pitch applications.

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“…Furthermore, an excessive deformation would create high stresses/strains. Several dominant failure mechanisms have been reported [2], [10], [11] including ACA/ACF delamination, loss of electrical contact during temperature variation, and long-standing fatigue failure of the adhesive due to material degradation at high temperature and moisture absorption etc.…”

Section: Introductionmentioning

confidence: 99%

A Study of Process-Induced Deformations of Anisotropic Conductive Film (ACF) Assembly

Cheng

Chen

et al. 2006

IEEE Trans. Comp. Packag. Technol.

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The warpage of glass substrate in chip-on-glass (COG) assemblies were believed to be the main cause of the so-called "Mura" phenomenon in thin-film transistor liquid crystal display (TFT-LCD) panels. The main objective of the study is to characterize the process-induced deformations of an anisotropic conductive film (ACF) type of COG assembly during the ACF bonding process. For effectively modeling the process-dependent thermal-mechanical behaviors of the ACF assembly, a process-dependent simulation methodology that integrates both thermal and thermal-mechanical finite element (FE) analyses and a "death-birth" meshing scheme is proposed. In the investigation, two various types of mirobump bonding technologies, i.e., the Au alloy and composite bumps, are explored. To substantiate the validity of the proposed methodology, the modeled results are extensively compared against experimental data. Moreover, the alternative goal of the study is to provide a design guideline through the exploration of the individual or combined effect of some essential parameters on the process-induced deformations.Both the modeled and experimental results reveal that in addition to the coefficient of thermal expansion (CTE) mismatch between the die and substrate, the process-induced temperature gradient appears to be the key factor causing the deformation of the assembly, and the deformed shape of the substrate is totally opposed to that obtained from isothermal modeling. Evidence also suggests that a preheated substrate could effectively ease the maximum process-induced warpage of the substrate, while the ACF fillet would unfortunately enlarge it. Besides, it is not surprising to find that an increase of the die length would enhance the maximum process-induced warpage of the substrate, but what surprises many is that an increase of the die width would diminish it.Index Terms-Anisotropic conductive film (ACF) bonding technology, death-birth meshing scheme, finite element (FE) modeling, parametric study, process-induced warpage, response surface methods (RSMs).

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Compliant bumps for adhesive flip chip assembly

Cited by 11 publications

References 0 publications

Highly reliable, fine pitch chip on glass (COG) joints fabricated using Sn/Cu bumps and non-conductive adhesives

Highly reliable, fine pitch chip on glass (COG) joints fabricated using Sn/Cu bumps and non-conductive adhesives

A novel compliant-bump structure for ACA-bonded chip-on-flex (COF) interconnects with ultra-fine pitch

A Study of Process-Induced Deformations of Anisotropic Conductive Film (ACF) Assembly

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