Wyniki 1-5 spośród 5 dla zapytania: authorDesc:"Barbara Dziurdzia"

Ball Grid Array failure diagnosis


  Ball grid array (BGA) packages, in which connections with outside circuits are performed through solder balls under a package, has become popular in recent years. BGA packages offer a much larger I/O counts for a given footprint area on a PCB as compared to a peripherally leaded devices such as quad flat pack (QFP). They provide also improved electrical performance, e.g. a lower electrical inductance and they are much more easy to handle and assembly without the concerns of lead coplanarity and bent leads. The disadvantage of the BGA configuration is, that visual inspection and individual repair of defective solder joints is difficult. Repair and rework has to be done by removing the entire defective BGA package and replacing it with a new or a reballed one [1, 2, 3]. The paper presents the methods of BGA failure diagnosis after rework. The rework was accomplished by two methods: with professional hot air rework station and with solder paste and equipment for SMT assembly. BGA inspection is carried out by electrical continuity tests, X-ray inspection, acoustic microscopy and metallographic cross-sections. The effect of thermal shocks (‑55°C, +125°C) and the sine wave vibrations in the frequency range from 20 Hz to 1,4 kHz on the BGA solder joint features is investigated. Test patterns BGA packages used in experiments were test components of BGA225T1.5C-DC15 type manufactured by the TopLine. They were 225-ball fine-pitch Plastic Ball Grid Arrays (FBGAs) with lead-free solder balls deposited on the BT (bismaleimide triazine) substrate of thickness 0.36 mm. The balls of diameter 0.76 mm and 1.5 mm pitch were made of Sn96.5Ag3.0Cu0.5 solder alloy. Fig. 1 shows the ball grid array in Hirox stereomicroscope. Fig. 2 shows the test component BGA225T1.5C-DC15 - its top view and the daisy chain loop. The BGA components were daisy chained "dummy components". Daisy chains provide information about the continuity of the BGA assem[...]

Grubowarstwowy katalityczny detektor jonizacyjny do mikroanalizatorów

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Opisano próbę realizacji w technologii warstw grubych katalitycznego reaktora umożliwiającego spalanie węglowodorów. Katalityczne detektory mają wiele zalet w porównaniu z detektorami płomieniowymi. Najważniejsze z nich to: - możliwość realizacji miniaturowych reaktorów, ponieważ [...]

Assembly and failure analysis of "dummy" PBGA

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Recently it has been observed the increase in the popularity and use of Ball Grid Array packages (BGA) which have the input/output (I/O) connections on the bottom side of the device in the form of small spheres. This type of configuration allows much larger I/O counts for a given footprint area on a PCB as compared with a conventionally peripherally leaded devices. Having no fragile leads, B[...]

Anode Supported Planar Solid Oxide Fuel Cell (SOFC) – novel design


  Solid Oxide Fuel Cells (SOFCs) are highly efficient energy conversion devices that transform chemical energy to electrical energy through the electrochemical reactions. SOFC consists of two ceramic electrodes (anode and cathode) separated by a dense ceramic electrolyte and it operates at high temperature in the range from 800°C to 1000°C. Oxygen ions formed at the cathode migrate through the ion - conducting electrolyte to the anode/ electrolyte interface where they react with fuel, producing water and releasing electrons that flow through an external circuit to the cathode/electrolyte interface [1-3]. Microstructure of the cathode, anode and electrolyte is important for the proper fuel cell operation. The electrolyte should be dense, gas-tight and ion conducting. The electrodes should be transparent for gases and have good electrical conductivity [4-6]. In a typical planar SOFC design, the cell components are configured as thin, flat plates and metallic or ceramic interconnects serve as gas flow channels and provide the electrical connection between the cells in a stack of cells. The article presents a novel design of the anode-supported high temperature solid oxide fuel cell (SOFC) which differs from the typical planar SOFC design by the multifunctional anode construction. The anode consists of the anode base with embedded fuel distribution channels, manifolds and waste product collectors, and two operating anodes deposited on the both sides of the base. The embedded channels are connected with the outside via inlet for fuel and outlet for the waste products. The operating anodes are permanently bonded with the anode base by sintering. The anode base supports two cells, serves as a common current collector and provides fuel distribution. The anode base and operating anodes are made of commercially available nickel oxide and yttria-stabilized zirconia (Ni/YSZ) green tapes and further components of the cell - electrolyte and [...]

Nanostruktury ZnO otrzymywane metodą chemicznego osadzania z roztworu


  Nanopręty oraz nanodruty takich półprzewodników jak: ZnO, SnO2, In2O3, WO3, wykazują o wiele korzystniejsze właściwości fizyko-chemiczne i mechaniczne, niż struktury o wymiarach większych. Spowodowane to jest dominującą rolą powierzchni w stosunku do objętości. Rosnąca powierzchnia właściwa zwiększa czułości sensorów, w których stosuje się te nanomateriały jako warstwy gazoczułe. Również z punktu widzenia ekonomii konstrukcje nano- są wyzwaniem ze względu na mniejsze zużycie surowców i energii. Tlenek cynku ZnO posiada właściwości, które powodują, że jest atrakcyjnym związkiem stosowanym między innymi w elektronice przy konstrukcji czujników, przezroczystych elektrod oraz przetworników piezoelektrycznych. Te charakterystyczne właściwości to przede wszystkim wysoka przerwa energetyczna (3,37 eV), ale także znaczny współczynnik piezoelektryczny e33=1,2 C/m2, łatwość wbudowywania płytkich domieszek powodujących silne przewodnictwo typu n przy zachowaniu bardzo dobrej transmisji w widzialnym obszarze widma. Metody wytwarzania nanostruktur generalnie można podzielić na [1]: top-down polegające na obróbce jednego k[...]

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