Rhoda B. Leron

Effect of Thickness and Phosphorus Content on Au/Pd/Ni(P) Metal Finish of Printed Circuit Board

Electroless nickel/electroless palladium/immersion gold [Au/Pd/Ni(P) or ENEPIG] pads consisting of layers of Ni(P) (200xa0μin), pure palladium (Pd) or palladium phosphorus (PdP) (2xa0μin, 4xa0μin or 6xa0μin), and gold (Au) (2xa0μin or 4xa0μin) were prepared using two different processes (wire bonding and lead-free soldering). Each of these processes was done with zero- or two-time reflow. Different tests on solderability, wettability, wire-bonding capacity, and corrosion resistance were performed on different combinations of ENEPIG pads formed using different combinations of processes and conditions. Scanning electron microscopy was also performed to examine the surface characteristics of the pads. It was found that the ENEPIG pad sample with the 4-μin-thick Au and 4-μin-thick PdP layers possessed stable wire-bonding capacity and excellent lead-free solder reliability. In addition, the ENEPIG–PdP systems showed better corrosion resistance, which is attributed to the presence of the amorphous PdP layer protecting the nickel layer.

Heat Capacities of Aqueous Ternary Mixtures of 2-Amino-2-Methyl-1, 3-Propanediol + Piperazine or Lithium Bromide

In this work, we reported the molar heat capacities, CP, of aqueous solutions of the sterically hindered amines 2-amino-2-methyl-1, 3-propanediol (AMPD), and its aqueous ternaries containing piperazine (PZ) or lithium bromide (LiBr). Measurements were performed in the temperature range 303.15 K to 353.15 K and atmospheric pressure by heat flow differential scanning calorimetry. The excess molar heat capacities, CP E , of the binary solutions were determined, and the data were represented as function of temperature and composition using a Redlichuf02dKister-type equation. The CP of the ternary mixtures was correlated with temperature and amine concentration using the Sohnel and Novotny equation. Results showed that the calculated data agree very well with experimental CP values at average absolute deviation values of less than 0.2%.