A heat stable trypsin inhibitor was found in the bran of soft-shelled job's-tears {Coix lacrymajobi L. var. Ma-yuenStapf) seeds. This inhibitor seemed to be a simple protein, and the molecular weight was about 12,000. Similar to other heat stable trypsin inhibitors, this inhibitor also contained manycysteine or cystine residues in the molecule. This inhibitor inhibited bovine trypsin at the molar ratio of 1 to 2, showing that it was double-headed. Its activity was stable against the change of pH at the range of3 to 1 1 and high temperature of 100°C under certain conditions. However, the degree of heat stability of the inhibitory activity depended highly upon the kind of the solution in which this inhibitor was dissolved.
In this study, 60 solder compositions were examined in an effort to improve the integrity against impact loads of the solder joints on an electroless Ni-P/Au surface finish. The Ag, Cu, and Ni contents in the Sn-based solder varied from 0 to 4.5 wt%, 0 to 2.0 wt%, and 0 to 0.05 wt%, respectively. Impact shear tests were performed to investigate solder joint integrity after solder ball reflowing, after reflow soldering twice more, after storage at room temperature for 168 hours, and after storage at 150°C for 1,000 hours. According to the results, the Ag content should be as low as possible, the Cu content should be from 0.5 to 0.7 wt%, and the Ni content should be as high as possible. The Ag and Ni contents should be determined in consideration of the wettability and the board-level reliability of the solder joints.
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