To improve the properties of Sn10Sb8Cu solder alloy, two new solders (SnSbCuAg and SnSbCuNi) were formed by adding small amounts of Ag or Ni into the solder alloy. The results show that the melting point of the SnSb...To improve the properties of Sn10Sb8Cu solder alloy, two new solders (SnSbCuAg and SnSbCuNi) were formed by adding small amounts of Ag or Ni into the solder alloy. The results show that the melting point of the SnSbCuAg solder alloy decreases by 14.1℃ and the spreading area increases by 16.5% compared to the matrix solder. The melting point of the SnSbCuNi solder alloy decreases by 5.4℃ and the spreading area is slightly less than that of the matrix solder. Microstructure analysis shows that adding trace Ag makes the melting point decline due to the dispersed distribution of SnAg phase with low melting point. Adding trace Ni, Cu6Sn5 and (Cu, Ni)6Sn5 with polyhedron shape on the copper substrate can be easily seen in the SnSbCuNi solder alloy, which makes the viscosity of the melting solder increase and the spreading property of the solder decline.展开更多
A general construction of inter-group complementary (IGC) codes is proposed based on perfect complementary (PC) codes,interleaving operation,and the orthogonal matrix.The correlation properties of the newly constructe...A general construction of inter-group complementary (IGC) codes is proposed based on perfect complementary (PC) codes,interleaving operation,and the orthogonal matrix.The correlation properties of the newly constructed IGC codes can be described as follows:(1) the autocorrelation sidelobes of the codes are zeros in the zero correlation zone (ZCZ);(2) the cross-correlation functions (CCFs) between any two different codes of the same group are zeros in the ZCZ;(3) the CCFs between any two codes of different groups are zeros everywhere.The key point of this construction is that the ZCZ length of the generated IGC codes can be chosen flexibly.It is well known that there is a limitation between the ZCZ length and the number of mates;that is,the smaller is the length of ZCZ,the more are the IGC codes that can be generated.Therefore,if we can choose the ZCZ length of the IGC codes flexibly according to the requirement of the system,more users can be accommodated in the system.展开更多
基金supported by the Program for Science & Technology Innovation Talents in Universities of Henan Province (No.2010HASTIT032)the City Key Technologies R & D Program of Luoyang (No.0801038A), China
文摘To improve the properties of Sn10Sb8Cu solder alloy, two new solders (SnSbCuAg and SnSbCuNi) were formed by adding small amounts of Ag or Ni into the solder alloy. The results show that the melting point of the SnSbCuAg solder alloy decreases by 14.1℃ and the spreading area increases by 16.5% compared to the matrix solder. The melting point of the SnSbCuNi solder alloy decreases by 5.4℃ and the spreading area is slightly less than that of the matrix solder. Microstructure analysis shows that adding trace Ag makes the melting point decline due to the dispersed distribution of SnAg phase with low melting point. Adding trace Ni, Cu6Sn5 and (Cu, Ni)6Sn5 with polyhedron shape on the copper substrate can be easily seen in the SnSbCuNi solder alloy, which makes the viscosity of the melting solder increase and the spreading property of the solder decline.
基金Project supported by the National Natural Science Foundation of China (Nos. 61001110,60773074,and 60903004)the China Post-doctoral Science Foundation (No. 20100470204)+1 种基金the Beijing Municipal Natural Science Foundation (No. 4082020)the National High-Tech R & D Program of China (Nos. 2007AA01Z213 and 2009AA01Z209)
文摘A general construction of inter-group complementary (IGC) codes is proposed based on perfect complementary (PC) codes,interleaving operation,and the orthogonal matrix.The correlation properties of the newly constructed IGC codes can be described as follows:(1) the autocorrelation sidelobes of the codes are zeros in the zero correlation zone (ZCZ);(2) the cross-correlation functions (CCFs) between any two different codes of the same group are zeros in the ZCZ;(3) the CCFs between any two codes of different groups are zeros everywhere.The key point of this construction is that the ZCZ length of the generated IGC codes can be chosen flexibly.It is well known that there is a limitation between the ZCZ length and the number of mates;that is,the smaller is the length of ZCZ,the more are the IGC codes that can be generated.Therefore,if we can choose the ZCZ length of the IGC codes flexibly according to the requirement of the system,more users can be accommodated in the system.