The effect of different bonding temperatures on the mechanical and electrical performance of NCF-bonded flip-chip-on-flex packages

2012 IEEE 62nd Electronic Components and Technology Conference

Zhan

Kao

et al. 2012

Section: Introductionmentioning

confidence: 99%

Low temperature bonding using non-conductive adhesive for 3D chip stacking with 30μm-pitch micro solder bump interconnections

2012 IEEE 62nd Electronic Components and Technology Conference

Zhan

Kao

et al. 2012

“…It has been widely used in displays and mobile handset devices [1][2][3][4][5][6][7][8][9][10][11], mainly in chip-on-flex (COF), chip-on-glass (COG), chip-on-board (COB) and chip-on-plastic (COP).Recently, this type of adhesive have been applied to Si chip stacking and shown an acceptable reliability performance [12]. However, the research in NCF used for chip stacking with fine pitch interconnections is seldom literatures.…”

Section: Introductionmentioning

confidence: 99%

Low temperature bonding of 30um pitch micro bump interconnection for 3D IC stacking using non-conductive adhesive

2011 6th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT)

Zhan

Huang

et al. 2011

For evaluating the feasibility of adhesive bonding by NCF (nonconductive film) in micro bump joints, three types of micro joints were adopted in this study. The structure of the type I micro joints was Cu/Ni/Au while that of the type II micro joints was Cu/Ni/Au micro bump joined with Cu/Sn solder micro bump. Both the type I and type II micro joint were bonded by using NCF. The structure of the type III micro joints were the same, but the type III micro joints were produced by eutectic bonding. For the type III micro joints, the micro gap between chips was wrapped by a capillary underfill. The bonding results revealed that the contact resistance of the NCF joints was in the range of 100 Ωm ~ 400 Ωm which was higher than that of eutectic joints. Electrical continuity of micro bump interconnection was monitored by measuring the contact resistance of four-point Kelvin structure and daisy chain during reliability test. Thermal cycling test and thermal humidity storage test were conducted to evaluate the reliability performance of these three types of micro interconnections. The reliability test displayed that the reliability performance of eutectic joints was better than that of the NCF joints. The study showed that NCF joints have great potential to be applied in low temperature bonding of fine pitch 3D IC stacking.

“…1. Intensive solutions have been reported so as to meet the fine pitch requirement and reliable interconnects, such as: (1) Improving bonding process parameter [4][5] (2) Changing geometry of Au-bumps [6][7] (3) Adopting finer diameter of conductive particles [1] (4) Using double-layer or multi-layer ACA materials [2][3]8] (5) Adding insulating particles into ACA materials [2] (6) Coating insulating layer around conductive particles [3] However, there remain many critical challenges for ultrafine pitch applications.…”

Section: Introductionmentioning

confidence: 99%

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

2009 59th Electronic Components and Technology Conference

Chuang

et al. 2009

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.