OBJECTIVES The purpose of this study was to evaluate in situ the occurrence of corrosion in the soldering point areas between the wire, silver brazing and band in Haas expanders. MATERIAL AND METHODS Thirty-four 7-12-year-old patients who needed maxillary expansion with a Haas expander were randomly assigned to two groups of 17 individuals each, according to the oral hygiene protocol adopted ...

As from July 1, 2006, the European Union officially enforced prohibition of the use of six designated hazardous substances under the restriction of hazardous substances (RoHSs), including lead, cadmium and others. In addition, as from 2008, the requirements of green products had been made stricter by adding prevented use of halogen as the standard. When confronted with the two harsh lead-free a...

Solder paste is the main soldering material used to form strong solder joints between printed circuit boards (PCB) and surface mount devices in the surface mount assembly (SMA). On average 60% of endof-line soldering defects can be attributed to inadequate performance of solder paste stencil printing. Recently, lead-free solder paste has been adopted by electronics manufacturers in compliance w...

In this paper an improved method has been presented to determine the solder joint shear strength of passive discrete surface mounted (SMD) chip components (like resistors and capacitors). To calculate the stress in a solder joint in the case of shear loading, the force applied should be measured and the amount of joined surface (wetted area of the component metallization) calculated. Using the ...

-Multilayer ceramic chip capacitor CDR-05 (MIL part number) is one of the most used parts in ISRO’s satellite program. Cracks evolved in ceramic chip capacitors CDR-05 (size: 1825and dielectric: X7R) of two different makesduring soldering process are studied in this paper. It has been observed that CDR-05 capacitors of one particular make (Manufacturer-A) more prone to crack during soldering on...

We present here the findings of Alpha’s Alloy Development Program on the next generation of low temperature alloys that can be used in reflow soldering temperatures from 170 to 200C. Approaches in alloy development, test methodologies and results are discussed. The alloy properties targeted for improvements include: Alloy strength, alloy ductility, microstructure stability, improvements in ther...

The thermal behavior of visible AIGaInP-GaInP ridge laser diodes is investigated numerically and experimentally. It is shown that various parameters critically influence the thermal resistance R of such devices. R is inversely proportional to the thermal conductivity of the heatsink. A substantial improvement in R-quite larger than in the AlGaAs system-is achieved for junction-side-down mountin...