Lead frame designs

In this electrolysis, the electrolyte is a 20% solution of the furan in methanol containing sodium bromide. The bromide ion plays an essential role since bromine and brominated furans are probably important intermediates in the anode chemistry. The cell is a 1 mm gap, plate and frame design with carbon anodes and steel cathodes the current density lies in the range OJ-0.2 Acm The organic yield is 97% and the current efficiency 80-95% provided the electrolyte is cooled so as to maintain its temperature below The several reductions at lead cathodes in sulphuric acid media may be illustrated by the process developed by Reilly Tar and Chemical in the USA. The conversion of interest was ... 

The bottom leadless package (BLP) is a peripheral package for replacing the thin small outline package (TSOP) for dynamic random access memory (DRAM) applications. This package uses a custom-designed lead-frame with wire bond interconnection at the chip level. A package with 46 I/O, 0.5 mm (0.02 in.) pitch, was subjected to numerous thermal cycles to determine the cycles-to-failure and the failure mechanisms (Ref 10). 

There has recently been a renewed interest in Sn whiskers because of the worldwide conversion to Pb-free solders and finishes in electronic manufacturing. Finishes are applied to printed circuit boards (PCBs) and to the lead frames used to connect device packages to printed circuit boards. Lead frames are typically made of a copper (Cu) or iron-nickel (FeNi) alloy plated with a Sn-Pb alloy. Fig. 5 is a schematic diagram of a lead frame cross section bonded to a chip-carrier package. The surface finish of the lead-frame leg is designed to provide surface passivation and enhanced solderability. Typical Pb-free surface finishes are eutectic Sn-Cu or pure Sn. Tin(Sn) whiskers readily grow on high-Sn content finishes under certain conditions. 

Fig. 5. Lead—Acid battery grid design variations showing A lugs, B feet, C frames, and D current carrying wire for (a) rectilinear design, (b) corner lug radial, (c) center lug radial, (d) corner lug expanded metal, and (e) plastic/lead composite.

The aforementioned requirements on surface stability are typical for all exposed areas of the metallic interconnect, as well as other metallic components in a SOFC stack (e.g., some designs use metallic frames to support the ceramic cell). In addition, the protection layer for the interconnect, or in particular the active areas that interface with electrodes and are in the path of electric current, must be electrically conductive. This conductivity requirement differentiates the interconnect protection layer from many traditional surface modifications as well as nonactive areas of interconnects and other components in SOFC stacks, where only surface stability is emphasized. While the electrical conductivity is usually dominated by their electronic conductivity, conductive oxides for protection layer applications often demonstrate a nonnegligible oxygen ion conductivity as well, which leads to scale growth beneath the protection layer. With this in mind, a high electrical conductivity is always desirable for the protection layers, along with low chromium cation and oxygen anion diffusivity. 

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