Evaluating fine-pitch chip-on-flex with non-conductive film by using multi-points compliant bump structure

Huang, Yu-Wei; Lu, Su-Tsai; Chen, Tai-Hong

doi:10.1109/eptc.2006.342737

Cited by 3 publications

(1 citation statement)

References 7 publications

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

confidence: 99%