Electric contact and socket for electrical part

Abstract

A contact pin includes a base material composed of a material having a conductive property and an outermost surface layer made of a material into which Sn is dissolved and diffused by applying heat.

The invention claimed is: 
     
       1. A socket for an electrical part, that is used for a burn-in test, comprising:
 a socket body, comprising an accommodation portion in which an electric terminal of the electrical part is accommodated, the electric terminal comprising a film on a surface thereof, the film comprising Sn, the accommodation portion comprising an electric contact which contacts the electric terminal, the electric contact comprising: 
 an intermediate layer comprising Ni, and 
 an outermost surface layer, on the intermediate layer, the outermost surface layer comprising Pd and Ag, 
 the outermost surface layer being formed directly on the intermediate layer, and 
 a weight ratio of the Ag in the outermost surface layer being larger than a weight ratio of the Pd in the outermost surface layer. 
 
     
     
       2. The socket for an electrical part according to  claim 1 , wherein the outermost surface layer of the electric contact includes a Pd—Ag plating layer. 
     
     
       3. The socket for an electrical part according to  claim 1 , wherein the outermost surface layer of the electric contact is a lamination of a Pd—Ag plating layer, and an Ag plating layer or a Pd plating layer. 
     
     
       4. The socket for an electrical part according to  claim 1 , wherein the outermost surface layer of the electric contact is a lamination of an Ag plating layer and a Pd plating layer. 
     
     
       5. The socket for an electrical part according to  claim 1 , wherein the outermost surface layer of the electric contact comprises Ag, Pd and another metal. 
     
     
       6. The socket for an electrical part according to  claim 1 , wherein
 Sn included in a solder is diffused into the outermost surface layer, and 
 the outermost surface layer has a tensile strength higher than a tensile strength of the solder, and an alloy containing both the outermost surface layer and the diffused Sn has a tensile strength higher than the tensile strength of the solder. 
 
     
     
       7. The socket for an electrical part according to  claim 6 , wherein the outermost surface layer is made of a lamination of a Pd—Ag alloy plating layer, a lamination of an Ag plating layer and a Pd—Ag alloy plating layer, or a lamination of the Ag plating layer and the Pd plating layer. 
     
     
       8. The socket for an electrical part according to  claim 1 , wherein the electric contact comprises a pin. 
     
     
       9. The socket for an electrical part according to claim 5, wherein the outermost surface layer of the electric contact comprises Ag, Pd and Au.  
     
     
       10. The socket for an electrical part according to claim 9, wherein the outermost surface layer contains a lamination of an Ag layer, a Pd layer and an Au layer.  
     
     
       11. A socket for an electrical part, that is used for a burn-in test, comprising an electric contact electrically connected to a terminal which is provided for an electrical part and comprises a solder film containing Sn on a surface thereof, wherein:
 the electric contact has a contact portion contacted to the terminal of the electrical part,   the contact portion comprises a lamination of layers into which the Sn of the solder film is diffused, and   the lamination of layers contains an intermediate layer and an outermost surface layer formed directly on the intermediate layer,   the outermost surface layer comprising
 a Pd layer which contains Pd, and 
 an Ag layer which contains Ag and is formed on the Pd layer, and 
   a weight ratio of the Ag in the outermost surface layer being larger than a weight ratio of the Pd in the outermost surface layer.    
     
     
       12. The socket for an electrical part according to claim 11, wherein the Pd layer and the Ag layer are plating layers. 
     
     
       13. A socket for an electrical part, that is used for a burn-in test, comprising an electric contact electrically connected to a terminal which is provided for an electrical part and comprises a solder film containing Sn on a surface thereof, wherein:
 the electric contact has a contact portion contacted to the terminal of the electrical part,   the contact portion comprises a lamination of layers into which the Sn of the solder film is diffused, and   the lamination of layers contains an intermediate layer and an outermost surface layer formed directly on the intermediate layer,   the outermost surface layer comprising
 a Pd layer which contains Pd, and 
 a Pd—Ag layer which contains alloy of Pd and Ag and is formed on the Pd layer, and 
   a weight ratio of the Ag in the outermost surface layer being larger than a weight ratio of the Pd in the outermost surface layer.    
     
     
       14. The socket for an electrical part according to claim 13, wherein the Pd layer and the Pd—Ag layer are plating layers.  
     
     
       15. A socket for an electrical part, that is used for a burn-in test, comprising an electric contact electrically connected to a terminal which is provided for an electrical part and comprises a solder film containing Sn on a surface thereof, wherein:
 the electric contact has a contact portion contacted to the terminal of the electrical part,   the contact portion comprises a lamination of layers into which the Sn of the solder film is diffused, and   the lamination of layers contains an intermediate layer and an outermost surface layer formed directly on the intermediate layer,   the outermost surface layer comprising
 a Pd—Ag layer which contains alloy of Pd and Ag, and 
 an Ag layer which contains Ag and is formed on the Pd—Ag layer, and 
   a weight ratio of the Ag in the outermost surface layer being larger than a weight ratio of the Pd in the outermost surface layer.   
     
     
       16. The socket for an electrical part according to claim 15, wherein the Pd—Ag layer and the Ag layer are plating layers.  
     
     
       17. A socket for an electrical part, that is used for a burn-in test, comprising:
 a socket body,   a accommodation portion which accommodates the electrical part,   an electric contact electrically connected to a terminal which is provided for an electrical part and comprises a solder film containing Sn on a surface thereof,   wherein:   the electric contact has a contact portion contacted to the terminal of the electrical part,   the contact portion comprises a lamination of layers into which the Sn of the solder film is diffused, and   the lamination of layers contains an intermediate layer and an outermost surface layer formed directly on the intermediate layer, and   the outermost surface layer comprising
 a Pd layer which contains Pd, and 
 an Ag layer which contains Ag and is formed on the Pd layer, and 
   a weight ratio of the Ag in the outermost surface layer being larger than a weight ratio of the Pd in the outermost surface layer.    
     
     
       18. A socket for an electrical part, that is used for a burn-in test, comprising:
 a socket body,   a accommodation portion which accommodates the electrical part,   an electric contact electrically connected to a terminal which is provided for an electrical part and comprises a solder film containing Sn on a surface thereof,   wherein:   the electric contact has a contact portion contacted to the terminal of the electrical part,   the contact portion comprises a lamination of layers into which the Sn of the solder film is diffused, and   the lamination of layers contains an intermediate layer and an outermost surface layer formed directly on the intermediate layer,   the outermost surface layer comprising
 a Pd layer which contains Pd, and 
 a Pd—Ag layer which contains alloy of Pd and Ag and is formed on the Pd layer, and 
   a weight ratio of the Ag in the outermost surface layer being larger than a weight ratio of the Pd in the outermost surface layer.    
     
     
       19. A socket for an electrical part, that is used for a burn-in test, comprising:
 a socket body,   a accommodation portion which accommodates the electrical part,   an electric contact electrically connected to a terminal which is provided for an electrical part and comprises a solder film containing Sn on a surface thereof,   wherein:   the electric contact has a contact portion contacted to the terminal of the electrical part,   the contact portion comprises a lamination of layers into which the Sn of the solder film is diffused, and   the lamination of layers contains an intermediate layer and an outermost surface layer formed directly on the intermediate layer,   the outermost surface layer comprising
 a Pd—Ag layer which contains alloy of Pd and Ag, and 
 an Ag layer which contains Ag and is formed on the Pd—Ag layer, and 
   a weight ratio of the Ag in the outermost surface layer being larger than a weight ratio of the Pd in the outermost surface layer.