Predictive design of flip-chip PBGA for high reliability and low cost

Author(s):  
L.L. Mercado ◽  
V. Sarihan
Author(s):  
D. Scott Copeland ◽  
M. Kaysar Rahim ◽  
Jeffrey C. Suhling ◽  
Guoyun Tian ◽  
Pradeep Lall ◽  
...  

In this work, we report on our efforts to develop high reliability flip chip on laminate assemblies for deployment in harsh thermal cycling environments characteristic of ground and aerospace vehicles (e.g. −55 to 150 °C). Reliability enhancement has been achieved through the use of a novel low expansion, high stiffness, and relatively low cost laminate substrate material that virtually eliminates CTE mismatches between the silicon die and top layer PCB interconnect. The utilized laminate features a sandwich construction that contains standard FR-406 outer layers surrounding a low expansion high thermal conductivity carbon fiber-reinforced composite core (STABLCOR®). Through both experimental testing and modeling, we have demonstrated that robust flip chip assemblies can be produced that illustrate ultra-high solder joint reliability during thermal cycling and extremely low die stresses. Liquid to liquid thermal shock testing has been performed on test assemblies incorporating daisy chain test die, and piezoresistive test chips have been used to characterize temperature dependent die stresses. In both sets of experiments, results obtained using the hybrid PCB laminate with FR-406 outer layers and carbon fiber core have been compared to those obtained with more traditional glass-epoxy laminate substrates including FR-406 and NELCO 4000-13. Nonlinear finite element modeling results for the low expansion flip chip on laminate assemblies have been correlated with the experimental data. Unconstrained thermal expansion measurements have also been performed on the hybrid laminate materials using strain gages to demonstrate their low CTE characteristics. Other experimental testing has demonstrated that the new laminate successfully passes toxicity, flammability, and vacuum stability testing as required for pressurized and un-pressurized space applications.


2002 ◽  
Vol 124 (3) ◽  
pp. 240-245 ◽  
Author(s):  
Johan Liu ◽  
Zonghe Lai

A reliability study on anisotropically conductive adhesive joints on a Flip-Chip/FR-4 assembly has been carried out. In the study, nine types of anisotropic conductive adhesive (ACA) and one nonconductive film (NCF) were used. In total, nearly one-thousand single joints were subjected to reliability tests in terms of temperature cycling between −40°C and 125°C with a dwell time of 15 minutes and a ramp rate of 110°C/min. The test chip used for this extensive reliability test had a pitch of 100 μm. Therefore, this work was particularly focused on evaluation on the reliability of ultra fine pitch flip-chip interconnections using anisotropically conductive adhesives on a low-cost substrate. The reliability was characterized by single contact resistance measurement using the four-probe method during temperature cycling testing up to 3000 cycles. The Mean Time To Failure (MTTF) (defined as 50% failure of all tested joints) are 650, 2500, and 3500 cycles when the failure definition is defined as 20% increase, larger than 50 mΩ and larger than 100 mΩ, respectively, using the in-situ electrical resistance measurement technique. Using the discontinuous (manual) measurement at room temperature by taking out the sample from the cycling chamber, the MTTF for the same joint system is around 2500 cycles in the case that the failure criteria is defined as 20% of the resistance increase, far better than the results from the in-situ measurement. The results show clearly that in optimized conditions, high reliability flip-chip anisotropically conductive adhesive joints on low-cost substrate can be achieved.


1991 ◽  
Vol 02 (04) ◽  
pp. 251-261 ◽  
Author(s):  
K.L. TAI

Multichip Module (MCM) packaging has been used in high-end systems, such as mainframe and supercomputers for some time. Rapid advances in VLSI technology and novel system architecture concepts have presented both challenges and opportunities for MCM technologists. We should not just try to find a solution, but also try to take a long-term view and plan the technological development. We would like to develop MCM technology which has a broad range of applications from consumer products to supercomputers. The technology should focus on low cost, high performance, compact size, and high reliability. We believe that it is most attractive to leverage IC technology and surface mount technology (SMT). Therefore we select Si wafer as the substrate, Al as the metallization, polyimide as the dielectrics, Ta-Si as the resistor material, and Si oxide and nitride as the dielectrics for capacitor. Flip-chip solder attachment are used to assemble chips on the substrate. We view our version of MCM as a “giant chip” rather than a miniaturized printed wiring board. This “giant chip” contains mixed device technologies which cannot be obtained by current device technology. The migration path should be from small to large module. The infrastructure of the CAD system and the testing system is critical for the development of MCM technology. Potential applications and implementations of MCM technology are given in this paper.


2003 ◽  
Vol 3 (4) ◽  
pp. 169-175 ◽  
Author(s):  
S. Barbagallo ◽  
F. Brissaud ◽  
G.L. Cirelli ◽  
S. Consoli ◽  
P. Xu

In arid and semiarid regions the reclamation and reuse of municipal wastewater can play a strategic role in alleviating water resources shortages. Public awareness is growing about the need to recycle and reuse water for increasing supply availability. Many wastewater reuse projects have been put in operation in European and Mediterranean countries adopting extensive treatment systems such as aquifer recharge, lagooning, constructed wetlands, and storage reservoirs, mainly for landscape and agricultural irrigation. In agricultural reuse systems, there is an increasing interest in extensive technologies because of their high reliability, and easy and low cost operation and maintenance. Wastewater storage reservoirs have become the option selected in many countries because of the advantages they present in comparison with other treatment alternatives, namely the coupling of two purposes, stabilization and seasonal regulation. This paper describes an example of a wastewater storage system, built in Caltagirone (Sicily, Italy). The storage results in a tertiary treatment of a continuous inlet flow of activated sludge effluents. The prediction of the microbiological water quality has been evaluated by means of a non-steady-state first-order kinetic model. Single and multiple regressions were applied to determine the main variables that most significantly affected die-off coefficients. The proposed model has been calibrated using the results of a field monitoring carried out during a period from March to October 2000.


2021 ◽  
Vol 6 (51) ◽  
pp. eaaz5796
Author(s):  
I. D. Sîrbu ◽  
G. Moretti ◽  
G. Bortolotti ◽  
M. Bolignari ◽  
S. Diré ◽  
...  

Future robotic systems will be pervasive technologies operating autonomously in unknown spaces that are shared with humans. Such complex interactions make it compulsory for them to be lightweight, soft, and efficient in a way to guarantee safety, robustness, and long-term operation. Such a set of qualities can be achieved using soft multipurpose systems that combine, integrate, and commute between conventional electromechanical and fluidic drives, as well as harvest energy during inactive actuation phases for increased energy efficiency. Here, we present an electrostatic actuator made of thin films and liquid dielectrics combined with rigid polymeric stiffening elements to form a circular electrostatic bellow muscle (EBM) unit capable of out-of-plane contraction. These units are easy to manufacture and can be arranged in arrays and stacks, which can be used as a contractile artificial muscle, as a pump for fluid-driven soft robots, or as an energy harvester. As an artificial muscle, EBMs of 20 to 40 millimeters in diameter can exert forces of up to 6 newtons, lift loads over a hundred times their own weight, and reach contractions of over 40% with strain rates over 1200% per second, with a bandwidth over 10 hertz. As a pump driver, these EBMs produce flow rates of up to 0.63 liters per minute and maximum pressure head of 6 kilopascals, whereas as generator, they reach a conversion efficiency close to 20%. The compact shape, low cost, simple assembling procedure, high reliability, and large contractions make the EBM a promising technology for high-performance robotic systems.


2017 ◽  
Vol 17 (6) ◽  
pp. 881-885 ◽  
Author(s):  
Luigi Guerriero ◽  
Giovanni Guerriero ◽  
Gerardo Grelle ◽  
Francesco M. Guadagno ◽  
Paola Revellino

Abstract. Continuous monitoring of earth flow displacement is essential for the understanding of the dynamic of the process, its ongoing evolution and designing mitigation measures. Despite its importance, it is not always applied due to its expense and the need for integration with additional sensors to monitor factors controlling movement. To overcome these problems, we developed and tested a low-cost Arduino-based wire-rail extensometer integrating a data logger, a power system and multiple digital and analog inputs. The system is equipped with a high-precision position transducer that in the test configuration offers a measuring range of 1023 mm and an associated accuracy of ±1 mm, and integrates an operating temperature sensor that should allow potential thermal drift that typically affects this kind of systems to be identified and corrected. A field test, conducted at the Pietrafitta earth flow where additional monitoring systems had been installed, indicates a high reliability of the measurement and a high monitoring stability without visible thermal drift.


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