Recent advances in anisotropic conductive adhesives (ACAs) materials and processing technology
This paper deals with three recent advances in the area of ACA materials and processing technologies, (1) wafer-level ACA, (2) ultrasonic ACA bonding, and (3) Solder ACAs. Patented idea of Wafer level package (WLP) ACA/NCA was introduced earlier as one of the promising ACA packaging technologies due to its advantages such as fewer processing steps, lower cost, and enhanced device performance compared to conventional single chip ACA packaging. WLP ACA can be widely used for flat panel display (FPD), general semiconductor packaging, and 3D-TSV applications because of cost and performance advantages. In addition, another patented novel anisotropic conductive film (ACF) bonding process using vertical ultrasonic vibration was also introduced in flex-on-board (FOB) and Touch Screen Panel(TSP) applications. The ACF temperature was precisely controlled by adjusting both U/S power and bonding pressure. The significant meaning of this technique are (1) significantly reduced ACF bonding time typically 1/3 ∼ 1/5 of conventional T/C bonding times in FOB applications, (2) less thermal damages especially for TSP assembly, and (3) compact and energy saving machine. Lastly, newly developed solder ACFs combined with Ultrasonic processing can increase twice the current handling capability of conventional Ni ACFs and show excellent reliability performance in FOB applications because of metallurgical bonding at the joint rather than physical contact of conventional ACAs.
Development on wafer level anisotropic conductive film for flip-chip interconnection
With the fast growth of multimedia, the packaging has to satisfy high interconnection density, high data throughput, miniaturization, easy thermal management and reliability needs while keeping a low cost. Flip-chip, which probably offers the best solution to meet these requirements, has been chosen by major companies in various configurations: FCOB (flip-chip on board), WLCSP (wafer level chip scale package) and WLP (wafer level packaging). Flip-chip interconnection using micro-balls is a common interconnection technique and major developments are being carried out on wafer bumping. In this paper, a new bumping approach on the IC wafer with z-axis ACF (anisotropic conductive film) is presented. This WL-ACF concept proposes a universal solution for bumping as there is no specific rule design to be taken into account. Moreover, the z-axis ACF developed at CEA-LETI gives the possibility of achieving lower pitch and pad area as well as good electrical contact and reliability. WL-ACF is evaluated on a specific test vehicle assembly and compared with localized micro insert bumping and hybridization with standard ACF.
Contractor Failure: Analysis
The possibility exists for any construction contractor to fail to filfill the contract requirements associated with a facility. Contractor failure occurs when a contractor is unable to perform his/her contractual duties, thus requiring the facility owner to invoke the contract's nonperformance clause. This paper provides aggregate contractor business failure statistics and outlines potential causes for failure. A framework to identify and quantify the associated costs is also introduced. Several case studies are presented to examine the cause and cost of failure and the means by which the facilities were completed. Alternatives available for project completion when contractor failure occurs are discussed. Recommendations to identify and monitor contractors at high risk for failure are outlined as well. This paper provides facility owners with a greater awareness of the possibility of contractor failure, how to quantify costs of contractor failure, and avoidance techniques.