Abstract:
A method of using a semiconductor device having a plurality of external contact terminals formed of springy wires, usable in a stable state free from variation of contact voltage for a long period even if a contact terminal repeatedly makes contact several hundreds or thousands of times. A tip end of the external contact terminal is plated with individually, selectively removable multiple films, and the plated films are individually, selectively removed by an etching treatment, in accordance with the degree of contamination of the tip end of the external contact terminal, and then the external contact terminal is rinsed and rendered reusable.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a semiconductor device having external contact terminals and a method for using the same and, particularty to a semiconductor device having external terminals, such as a semiconductor socket having a number of springy external contact pins or terminals of a micro-spring system, which are used while being brought into contact with pads or solder balls of an interposer or a connector board. 
   2. Description of the Related Art 
   In the prior art, in a semiconductor device having a number of springy external contact pins or terminals of a micro-spring type, used as a test probe or otherwise, the external contact pin or terminal is made, for example, of a gold (Au) wire for bonding, which surface is plated with palladium (Pd), indium (in) or others. In such a semiconductor device, while the contact terminals repeat making contact with pads or solder balls on an interposer or a connector board several hundreds or thousands times, a surface of the terminal may be become contaminated or adhered with dirt or solder transferred from the mating object, which increases the electric contact resistance of the external terminal, causing a problem particularly in a high-frequency probe pin in that a test signal is not accurately transmitted even if the adhered solder is slight in amount. 
   In general, a terminal portion of the semiconductor socket of this kind used as a probe pin is periodically rinsed. However, even though the rinsing is carried out, it is difficult to completely remove the dirt which has been once adhered. Accordingly, there is a problem in that the contact resistance is difficult to maintain at a low level in a stable manner for a long period, which means that the device is not durable against a long term use in a stable state. In addition, as the semiconductor device or the like is generally expensive, it is not economical to frequently replace it with a new one. 
   There have been various prior arts related thereto as follows. When a laminated film of copper and tin/copper alloy is formed by a single electrolytic plating bath, the plating is carried out in such a manner that an electric potential at which copper is deposited and that at which copper and tin are deposited together are alternately and pulsatively applied to the plating bath (Japanese Unexamined Patent Publication No. 2002-256482); a copper (Cu) layer and an indium (In) layer are alternately formed on a surface of an object to be plated (Japanese Unexamined Patent Publication No. 2002-256478); a wire forming a contact terminal is coated, for example, with a resin so that a tip end of the wiring is exposed from the resin (Japanese Unexamined Patent Publication No. 2000-200804); electrolytic gel is used for removing an unnecessary solder layer or an oxide layer thereof adhered or deposited onto a surface of a contact portion of an IC socket without detaching the IC socket from a printed circuit board (Japanese Unexamined Patent Publication No. 2001-9398); an abrasive layer is provided on a plate-like elastic member of an IC socket to compensate the deterioration of contacts by the opening/closing operation (Japanese Unexamined Patent Publication No. 11-233220); an electrode of an IC socket is dipped in a solder-removal liquid with an acidic agent, rinsed with pure water, and then dried (Japanese Unexamined Patent Publication No. 7-234262); and a pair of terminals are provided so that one of them is brought into contact with the upper surface of a support board generally parallel thereto (Japanese Patent Publication No. 2892505). 
   As described above, in the prior art external contact pin or terminal of a micro-spring system, the surface thereof is variously treated or plated for the purpose of preventing the electric contact resistance from increasing due to the contamination or the adhesion of foreign matter on the surface. However, a method has not yet been found by which the external pin could be used in a stable state for a long period even if the contact is repeated several hundreds or thousands times. 
   SUMMARY OF THE INVENTION 
   The present invention has been made under such the circumstance, and the problem to be solved is to provide a semiconductor device having a number of springy external contact pins or terminals of a micro-spring system, usable for a long period free from the variation of a contact voltage of the respective contact pin or terminal even if it has repeated the contact several hundreds or thousands times, and a method for using the semiconductor device. 
   To achieve the above problem, according to the present invention, there is provided a semiconductor device comprising: a substrate body; a plurality of external terminals formed of springy wires, the external terminals arranged on and extending from the substrate body; each of the external terminals having a base end connected to the substrate body and a tip end apart from the base end; and each of the external terminals being plated at least the tip end thereof with multiple films which are removable by an etching treatment. 
   The springy wires are formed of gold, and the multiple films comprises a nickel or nickel alloy plated on a surface of the wire, and a gold film and a palladium film alternately plated thereon. 
   Alternatively, the springy wires are formed of gold, and the multiple films comprises a nickel or nickel alloy plated on a surface of the wire, and a gold film and a indium film alternately plated thereon. 
   According to another aspect of the present invention, there is provided a semiconductor device comprising: a substrate body; a plurality of external terminals formed of springy wires, the external terminals arranged on and extending from the substrate body; each of the external terminals having a base end connected to the substrate body and a tip end apart from the base end; an insulating resin layer formed on the substrate body in such a manner that at least a portion including the tip end is exposed from the insulating resin layer; and each of the external terminals being plated at least the exposed portion thereof with multiple films which are removable by an etching treatment. 
   Preferably, the insulating resin is an elastomeric material, such as silicone rubber. 
   According to still another aspect of the present invention, there is provided a method of using a semiconductor device, the device a substrate body; a plurality of external terminals formed of springy wires, the external terminals arranged on and extending from the substrate body; each of the external terminals having a base end connected to the substrate body and a tip end apart from the base end; and each of the external terminals being plated at least the tip end thereof with multiple films which are removable by an etching treatment; the method comprising: removing the plated film by an etching treatment in accordance with a degree of contamination of the tip end; and rinsing this semiconductor device to reuse the same. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional view of a support board used in the present invention; 
       FIG. 2  is a sectional view showing a state in which micro-springs are bonded to the support board; 
       FIG. 3  is a sectional view showing a state in which the support board is attached to a test board; 
       FIG. 4  is a sectional view showing a state in which the attachment of the support board to the test board has been completed; 
       FIG. 5  is a sectional view showing a state in which a package is attached; 
       FIG. 6  is a sectional view showing a state in which the attachment of the package has been completed; 
       FIG. 7  is a view showing states of a tip end of the micro-spring; 
       FIG. 8  is a view of another embodiment of the present invention corresponding to  FIG. 2 ; 
       FIG. 9  is a view of the other embodiment of the present invention corresponding to  FIG. 4 ; and 
       FIG. 10  is a view of the other embodiment of the present invention corresponding to  FIG. 6 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiments of the present invention will be described in detail, below, with reference to the attached drawings. 
     FIGS. 1 to 4  illustrate a series of processes for producing the inventive semiconductor device having external contact terminals. First, in  FIG. 1 , a support board  10  is prepared, in which conductor pads  11  and wirings  12  are provided for forming micro-springs (external contact pins of terminals). This support board  10  may be any of various boards generally used as a board for a semiconductor device, such as a glass-epoxy resin board or a ceramic board. 
   In general, a number of conductor pads  11  for forming the micro-springs are arranged both on front and back surfaces of the support board in the X direction and the Y direction at a pitch. The wirings  12  are connected to the conductor pads  11 , respectively. There are through-hole wirings among the wirings  12 , for connecting the conductor pads  11  respectively formed on the front and back surfaces of the support board  10  to each other. 
   In the vicinity of opposite ends of the support board  10 , through-holes  13  are formed for positioning and fixing this support board  10 . 
   In  FIG. 2 , a micro-spring  20  of metal such as gold (Au) is provided as an external contact terminal on the respective conductor pad  11  by a wire-bonding method. As a wire-bonding apparatus (not shown), a conventional one used for connecting an electrode of a semiconductor chip to a lead with a wire in the conventional process for producing a semiconductor device may be adopted. 
   In one embodiment of the present invention, gold (Au) is used as a material of the micro-spring formed by the wire-bonding method. The micro-spring  20  is bonded to the conductor pad  11  at one end, and extends to form a generally L-shape as seen from a lateral side of the support board  10 , which is then cut to form the other end. As seen in the plan view of the support board  10 , the micro-spring  20  obliquely extends at a predetermined angle (for example, 30 degrees) relative to the direction (the X direction) of a row of the conductor pads  11 . For example, the pitch of the conductor pads  11  and the micro-springs  20  is 0.5 mm in the X direction. Also, the micro-spring  20  has a vertical height from the proximal end to the distal end thereof of 0.56 mm and a horizontal length of 0.65 mm, and is gently curved from the proximal end to the distal end to form an L-shape or an S-shape. 
   Then, although not shown, at least the tip portions of a number of micro-springs  20  are dipped into a plating bath to be subjected to the plating process. As described later, a nickel film or a nickel alloy film is initially formed, and then a gold film and a palladium film are alternately i.e., successively, laminated thereon by the plating process. Or a gold film and an indium film may be alternately i.e., successively, laminated on the nickel film or the nickel alloy film. 
   In  FIGS. 3 and 4 , a process is illustrated, for bringing the support board  10  into contact with a test board  30 . Also on the surface of the test board  30 , conductor pads  31  (wirings) are formed in correspondence to the arrangement of micro-springs  20  on the support board  10  to be in contact with the micro-springs  20  of the support board  10  when mounted. Also, the test board  30  has positioning holes  33  at positions in correspondence to the positioning through-holes  13  of the support board  10 . 
   A fastening jig  35  is used for positioning and fixing the support substrate  10  to the test board  30 , and includes pins  37  fitting into the holes  33  of the test board  30  and pins  36  fitting into the through-holes  13  of the support board  10 . First, the pins  37  of the fastening jig  35  are fitted into the holes  33  of the test board  30  to position the fastening jig  35  to the test board  30 . Thereafter, the through-holes  13  of the support board  10  are fitted to the pins  36  of the fastening jig  35  to position and fix the support board  10  to the fastening jig  35  and the test board  30 . 
   A package guide  40  has pins  41  fitting into the positioning through-holes  13  of the support board  10  and a guide portion  42  for mounting a package thereon. The guide portion  42  has shoulders and corners corresponding to edges and four corners of the rectangular package. 
   As shown in  FIG. 4 , when the support board  10  is positioned and fixed relative to the test board  30 , the tip ends of the respective micro-springs  20  of the support board  10  are brought into contact with the respective conductor pads  31  of the test board  30 . At that time, as the micro-springs  20  are formed of springy metallic wire, the micro-springs  20  are brought into contact with the conductor pads  31  while being subjected to the elastic deformation. 
     FIGS. 5 and 6  illustrate a process for carrying out the test of the package  50  by mounting the package  50  on the package guide  40 . The package  50  has external connecting terminals  52  (wirings) arranged in correspondence to the arrangement of micro-springs  20  of the support board  10  and formed to be in contact with the micro-springs  20  of the support board  10  when mounted. 
   Accordingly, when the package  50  is mounted to the guide portion  42  of the package guide  40  and pushed and fixed by a pressing jig  54 , the tip ends of the micro-springs  20  of the support board  10  are brought into contact with the respective external connecting terminals  52  of the package  50 . At this time, in the same manner as described before, as the micro-springs  20  are formed of springy metallic wire, the micro-springs  20  are brought into contact with the external connecting terminals  52  while being subjected to the elastic deformation. In one example, the “deformation” of the tip end of the micro-spring  20  when it is in contact with the pad  31  or the terminal  52 , that is, a “pressed amount”, may be  50  μm or more. Also, the contact resistance may be 0.1Ω or less. 
   In this regard, while the package is tested in  FIG. 6 , a semiconductor chip or a semiconductor wafer may be, of course, tested in the same manner instead of the package. 
     FIG. 7  illustrates a shape of a tip end of the micro-spring  20 . The gold wire is vertically provided on the conductor pad  11  of the support board  10  by using a wire-bonding apparatus (not shown), and bent to form a generally L-shape to define the micro-spring  20 . In the present invention, however, at least a tip end of the micro-spring  20  is plated to have a multi-layered metallic film. 
   Initially, a nickel film or a nickel alloy film  22  is formed on the surface of the gold wire material  21 . Then, a gold (Au) film  23  and a palladium (Pd) film  24  are alternately laminated thereon by the plating. Although one gold (Au) film  23  and one palladium (Pd) film  24  are solely illustrated in  FIG. 7 , these films may be repeatedly laminated. Instead of the palladium (Pd) film  24 , the gold film and an indium (In) film may be alternately laminated. 
   When the inventive semiconductor device having the external contact terminals has been used for a long period as a semiconductor socket whereby the attachment and detachment thereof relative to the test board or the package are repeated a number of times, contaminant  25  such as solder may be adhered to the tip end of the micro-spring  20  as shown in  FIG. 7(   a ). According to the present invention, the package pressing jig  54 , the package guide  40  and the fastening jig  35  are easily removable to detach the support board  10  from the tester. 
   Then, the micro-springs  20  of the support board  10  are dipped in an etching liquid to be subjected to the etching treatment. At this time, if the outermost layer of the tip end of the micro-spring  20  is the gold film, an etching liquid capable of dissolving gold (Au) but not reactive with palladium (Pd) or indium (In) is selected. On the contrary, if the outermost layer of the tip end of the micro-spring  20  is the palladium (Pd) film or indium (In) film, another etching liquid capable of dissolving palladium (Pd) or indium (In) but not reactive with gold (Au) may be selected. By such an etching treatment, the dirt due to solder or the like adhered to the surface of the tip end of the micro-spring  20  is removed together with the outermost layer thereof as shown in  FIG. 7(   b ). Thereafter, the micro-spring  20  is rinsed so that the surface thereof is free from the dirt to be usable again as a semiconductor socket as shown in  FIG. 7(   c ). 
   As described above, according to the present invention, a plurality of kinds plated films are alternately laminated on the micro-spring  20 , which are soluble in etching liquids, respectively, different from each other. Thereby, it is possible to solely dissolve the plated film of the outermost layer and not to damage the micro-spring  20  due to the excessive etching. Thus, the dirt of the micro-spring  20  is removable a plurality of times (corresponding to the number of the plated films) by the etching treatment. If the multi-layered metallic film has been completely removed by the repeated etching treatment, the micro-spring  20  is again alternately laminated with a plurality of kinds plated films which are soluble in etching liquids, respectively, different from each other, and may be reusable. 
   When it is desired to always provide a special plated film on the outermost layer of the micro-spring in view of the contact resistance (for example, in a multi-layered metallic film in which a gold film and a palladium film are alternately laminated, when it is desired to always provide the gold film on the outermost layer), the outermost gold film is removed by the etching treatment, then the next palladium film is subjected to the etching treatment to expose the gold film on the surface. 
     FIGS. 8 to 10  illustrate a modification of the preceding embodiment of the present invention, in which  FIGS. 8 ,  9  and  10  correspond, respectively, to the processes shown in  FIGS. 2 ,  4  and  6 . In this modification, the micro-springs  20  are embedded in an elastomeric layer  27  of a suitable resin such as a silicone resin having a rubber-like elasticity so that the tip ends of the micro-springs  20  are exposed outside. Such an elastomeric layer  27  may be molded, for example, by the potting of resin. 
   Also in this embodiment, the micro-spring  20  itself may be formed by using the wire-bonding method of gold wire In the same manner as in the preceding embodiment. On the tip end of the micro-spring  20  exposed out of the elastomeric layer  27 , the surface of the gold wire material  21  is covered with the nickel or nickel alloy film  22  formed by the plating, on which the gold film  23  and the palladium film (or indium film)  24  are alternately laminated by the plating as described before. In this regard, a portion to be plated may be a whole micro-spring  20  or solely the tip end thereof exposed out of the elastomeric layer  27 . 
   When the dirt  25  due to solder or the like has been adhered to the tip end of the micro-spring  20  after the long term use, the support board  10  is removed from the tester in the same manner as described before, and the micro-springs  20  are dipped in the etching liquid and subjected to the etching treatment to remove the outermost plated film, after which they are rinsed to remove the solder dirt or others adhered to the surface. Thus, the micro-springs  20  are reusable. 
   In the embodiment shown in  FIGS. 8 to 10 , the deformation of the micro-spring  20  due to external force can be prevented by virtue of the elastomeric layer  27 . Accordingly, even though the micro-springs  20  are brought into contact with the jigs or others during the etching treatment or the rinsing thereof, it is possible to prevent the micro-springs  20  from being deformed. 
   It should be understood by those skilled in the art that the foregoing description relates to only some of preferred embodiments of the disclosed invention, and that various changed and modifications may be made to the invention without departing from the spirit and scope thereof. 
   As described hereinbefore, according to the present invention, even if the electric contact resistance increases due to the adhesion of dirt or foreign matter on the surface of the external contact pins or terminals of a micro-spring system after the repetition of contact several hundreds or thousands times, it is possible to reuse the inventive semiconductor device as a semiconductor socket by an extremely easy method because the tip end of the contact terminal has a multi-layered plated film and the outermost film is removed by the etching treatment and the rinsing. Thus, the inventive semiconductor device could be used as a semiconductor socket or others in a stable state for a long period.