Abstract:
The invention provides a high-frequency vertical spring probe card structure including a plurality of probes. Each of the probes includes at least one conducting layer and at least one insulating layer. The conducting layer includes a first contact end and a second contact end used for electrically contacting an external component while the probe is compressed and includes a probe body including at least one plate portion and at least one resilient portion connected to each other. The plate portion is used for supporting deformation of the resilient portion while the resilient portion is compressed vertically. The insulating layer includes at least one plate member tightly attached to the plate portion of the conducting layer correspondingly. The probe structure of the invention is simple and can be formed as multi-layer stack structure by electroplating through Lithographie GaVanoformung Abformung (LIGA) technology.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a probe structure and, more particularly, to a high-frequency vertical spring probe card structure, which is a new design of micro probe structure and can be used for testing high-frequency and high-speed chip. The probe of the invention can maintain good contact status during testing when the probe is compressed vertically. 
         [0003]    2. Description of the Prior Art 
         [0004]    In semiconductor industry, a die of a chip has to be tested by probes through related testing instrument and software before package so as to sieve good products and bad products. Afterward, the good products are delivered to package process. 
         [0005]    Since integrated circuit process advances continuously, line width and pitch between circuits are getting smaller and smaller. The probe for testing is changed from a horizontal cantilever-type probe with curved tip to a vertical probe with small diameter. The vertical probes can be arranged tightly and the pitch between two vertical probes is narrow. Referring to  FIG. 1 ,  FIG. 1  is a schematic diagram illustrating a conventional vertical probe structure. As shown in  FIG. 1 , the conventional probe  90  is a spring-type probe formed by machining process. The conventional probe  90  consists of a sleeve  91 , a contact end  92 , a shaft  93  and a spring  94 . The contact end  92  is used for contacting an object (e.g. die) for electrical testing. The other end opposite to the contact end  92  contacts a circuit board. The spring  94  is wound around a periphery of the shaft  93  so as to enhance elasticity of the probe  90 . Then, the assembly of the shaft  93  and the spring  94  is disposed in the sleeve  91  so as to complete complicated assembly process of the conventional probe  90 . 
         [0006]    However, the aforesaid conventional probe still has lots of disadvantages. First, it requires much time and work to assemble each probe by labor and the cost increases accordingly. Furthermore, since the contact end of the aforesaid probe has a column shape, testing stability will be influenced if the evenness of the contact end is bad. Still further, it is difficult to manufacture and assemble a great quantity of conventional probes due to limitation of the shape and the pitch between two probes cannot be reduced. Moreover, parts of the aforesaid are exposed without insulation, so it may generate additional capacitance and inductance easily and is not suitable for high-frequency testing. Therefore, the invention provides a high-frequency vertical spring probe card structure to solve the aforesaid problems. 
       SUMMARY OF THE INVENTION 
       [0007]    An objective of the invention is to provide a high-frequency vertical spring probe card structure, which is a new design of micro probe structure and can be used for testing high-frequency and high-speed chip. 
         [0008]    Another objective of the invention is to provide a high-frequency vertical spring probe card structure, which can be formed as a multi-layer probe by Micro-Electro-Mechanical System (MEMS) process or formed by Lithographie GaVanoformung Abformung (LIGA) technology rapidly and simply. 
         [0009]    Another objective of the invention is to provide a high-frequency vertical spring probe card structure, wherein a probe body has non-uniform elasticity from top to bottom. The invention determines the configuration of the probe according to the acting force applied to the probe. Accordingly, the maximum deformation of the probe can be increased by simple design. 
         [0010]    To achieve the aforesaid objectives, the invention provides a high-frequency vertical spring probe card structure comprising a plurality of probes. Each of the probes comprises at least one conducting layer and at least one insulating layer. The conducting layer comprises a first contact end and a second contact end used for electrically contacting an external component while the probe is compressed and comprises a probe body comprising at least one plate portion and at least one resilient portion connected to each other. The plate portion is used for supporting deformation of the resilient portion while the resilient portion is compressed vertically. The insulating layer comprises at least one plate member tightly attached to the plate portion of the conducting layer correspondingly. 
         [0011]    The high-frequency vertical spring probe card structure of the invention has following advantages: 
         [0012]    1) The high-frequency vertical spring probe card structure can be manufactured by advanced process (e.g. LIGA process, etc.) so as to form multi-layer probe. Compared to conventional machining process, the invention can save much time and cost. 
         [0013]    2) According to the aforesaid advantage, the multi-layer probe manufactured by advanced process has better evenness than the conventional probe, so it can increase testing stability. However, the conventional machining process cannot guarantee that all conventional probes can contact corresponding contact points stably. 
         [0014]    3) The lateral shape of the high-frequency vertical spring probe card structure is flatter than that of the conventional probe, so more probes can be installed on the probe card of the invention. Furthermore, the pitch between two probe tips is also smaller than that of the conventional probe such that the invention can satisfy a great quantity of probes needed by industry. 
         [0015]    4) The high-frequency vertical spring probe card structure further has the insulating layer except the conductive layer. Compared to the conventional probe without insulation, the invention will not generate additional capacitance and inductance, can improve signal strength, and can reduce audio stream. Therefore, the high-frequency vertical spring probe card structure can be applied to high-frequency testing. 
         [0016]    5) The high-frequency vertical spring probe card structure may use two probes to contact one single solder ball and the design of the other end can increase the pitch. The upper contact ends contact different circuit boards so as to achieve effects of withstanding current and withstanding voltage and reduce signal interference. Consequently, the invention can achieve precision measurement and enhance testing current and power range of chip. 
         [0017]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a schematic diagram illustrating a conventional vertical probe structure. 
           [0019]      FIG. 2  is a schematic assembly diagram illustrating a probe structure according to a first embodiment of the invention. 
           [0020]      FIG. 3  is a schematic exploded diagram illustrating the probe structure according to the first embodiment of the invention. 
           [0021]      FIG. 4  is a schematic assembly diagram illustrating a multi-layer probe structure according to a second embodiment of the invention. 
           [0022]      FIG. 5  is a schematic exploded diagram illustrating the multi-layer probe structure according to the second embodiment of the invention. 
           [0023]      FIG. 6  is a schematic cross-sectional diagram illustrating the probe of the first embodiment being used. 
           [0024]      FIG. 7A  is a schematic diagram illustrating a first type of the resilient portion of the invention. 
           [0025]      FIG. 7B  is a schematic diagram illustrating a second type of the resilient portion of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Referring to  FIG. 2 ,  FIG. 2  is a schematic assembly diagram illustrating a probe structure according to a first embodiment of the invention. The probe  1  of the invention comprises a first contact end  21 , a second contact end  22  and a probe body  23 . The first contact end  21  and the second contact end  22  are used for electrically contacting an external component while the probe  1  is compressed. The probe body  23  comprises a plurality of plate portions  231  and a plurality of resilient portions  232 , wherein the plate portions  231  and the resilient portions  232  are connected to each other. The plate portions  231  are used for supporting deformation of the resilient portions  232  while the resilient portions  232  are compressed vertically. Furthermore, the probe  1  is flat so a plurality of probes  1  can be arranged in parallel with lateral surface (i.e. the smaller surface of the probe) . Therefore, the invention can dispose more and more probes  1  on testing components or circuit boards with the same area by the aforesaid parallel arrangement so as to satisfy a great quantity of probes needed by probe testing device. 
         [0027]    Referring to  FIG. 3 ,  FIG. 3  is a schematic exploded diagram illustrating the probe structure according to the first embodiment of the invention. In this embodiment, the aforesaid probe will be depicted in detail. The probe (not labeled in  FIG. 3 ) comprises a conducting layer  2  and an insulating layer  3 . The conducting layer  2  is made of conductive material, such as conductive metal, conductive alloy or the like. The insulating layer  3  is made of non-conductive material, such as electrical insulation material or the like. The conducting layer  2  and the insulating layer  3  may be formed by electroplating through Lithographie GaVanoformung Abformung (LIGA) technology or formed as a multi-layer micro-probe by Micro-Electro-Mechanical System (MEMS) process. The conducting layer  2  and the insulating layer  3  of each probe are separated by each other. The probe body  23  of the conducting layer  2  comprises a plurality of plate portions  231  corresponding to a plurality of plate members  331  of the insulating layer  3 . Once the probe is compressed, the plate portions  231  and the plate members  331  can support deformation of the resilient portions  232  and reinforce elasticity of the resilient portions  232  so as to prevent the probe from fracturing due to great deformation. Furthermore, the resilient portion  232  may further has at least one force restricting protrusion  233  for preventing or restricting the probe from fracturing once the resilient portion  232  is over-compressed. When the probe is compressed vertically, the resilient portion  232  is bended due to compression. Once the resilient portion  232  is over-compressed, the force restricting protrusion  233  will contact the opposite force restricting protrusion  233 . At this time, the resilient portion  232  has been bended to the maximum deformation and is restricted by the force restricting protrusion  233  such that the probe is not compressed anymore so as to prevent the resilient portion  232  from fracturing due to over-compression. As mentioned in the above, since the probe body  23  has the resilient portion  232 , the plate portion  231  and the force restricting protrusion  233 , the life span of the probe can be extended effectively. 
         [0028]    Besides the aforesaid first embodiment, the invention also provides a multi-layer stack probe for different testing devices. Referring to  FIGS. 4 and 5 ,  FIG. 4  is a schematic assembly diagram illustrating a multi-layer probe structure according to a second embodiment of the invention, and  FIG. 5  is a schematic exploded diagram illustrating the multi-layer probe structure according to the second embodiment of the invention. The second embodiment is for multi-layer stack probe. As shown in  FIG. 4 , the conducting layer  2  and the insulating layer  3  of the probe  1 B are separated by each other and can be formed in the following order of conducting layer  2 , insulating layer  3 , conducting layer  2 , and so on. The number of layers can be increased or decreased according to testing requirement. Each of the conducting layers  2  comprises a plurality of plate portions  231  and a plurality of resilient portions  232 , wherein the plate portions  231  and the resilient portions  232  are connected to each other. Each of the insulating layers  3  also comprises a plurality of plate members  331 , as shown in  FIG. 5 . Furthermore, the aforesaid flat probes  1  can be arranged in parallel so as to reduce the pitch between every two probe tips such that the space within limit range can be utilized effectively to accommodate more probes  1 . Accordingly, the multi-layer probe  1 B may has a plurality of contact tips (i.e. first contact end  21 ) contacting one single solder ball. The principle of the second embodiment is the same as that of the first embodiment and the related explanation will not be depicted herein again.  FIG. 4  shows a probe with three layers. Each of the probes can be formed by stacking and staggering a plurality of conducting layers  2  and a plurality of insulating layers  3 . The multi-layer stack probe shown in  FIG. 4  is one embodiment of the invention and the scope of the invention is not limited to this embodiment. 
         [0029]    Referring to  FIG. 6 ,  FIG. 6  is a schematic cross-sectional diagram illustrating the probe of the first embodiment being used. The probe card  4  comprises a circuit board  5 , a fixing component  6  and a plurality of probes  1 . The circuit board  5  connects the fixing component  6  and the signal metal pad  51 . A plurality of accommodating spaces  61  is formed in the fixing component  6  and below the circuit board  5 . The probe  1  is accommodated in the accommodating space  61 . The probe  1  is fixed in the probe card  4  by the fixing component  6 . Due to the fixing component  6 , the probes  1  can be only compressed vertically and cannot move laterally or in other directions. When the probe  1  is fixed, the second contact end  22  electrically contacts the signal metal pad  51  such that the probe is electrically connected to the circuit board  5 . During testing, the probe card  4  moves over a testing machine. When the probe  1  of the probe card  4  gets close to a testing component  7  (e.g. chip or circuit board), the first contact end  21  of the probe  1  electrically contacts the solder ball  71  on the testing component  7  so as to determine the quality of the testing component  7 . The circuit board  5  and the fixing component  6  can be connected to each other by screwing device or other auxiliary fixing device such that the invention can be applied to a probe card product. The probe  1  of the invention can be applied to many products. The aforesaid embodiment is used for illustration purpose only and the scope of the invention is not limited to the embodiment. 
         [0030]    The probe  1  of the invention is not limited to use the first contact end  21  to contact the solder ball  71  of the testing component  7 . In other words, the probe  1  can be also installed in the fixing component  6  inversely so as to use the second contact end  22  to contact the solder ball  71  of the testing component  7 . Furthermore, the probe of the invention can be also installed between two circuit boards for purpose of electric and signal transmission. Moreover, though the contact tip (i.e. the first contact end  21 ) of the invention is formed as V-shape, the contact tip is not limited to V-shape and the shape of the contact tip can be determined based on practical applications. It should be noted that the contact tip has to provide good contact status and stable signal transmission while the probe electrically contacts the external component no matter what the shape of the contact tip is. The number of the first contact end  21  and the second contact end  22  is not limited to one and it can be determined based on the number of stack layers. 
         [0031]    Referring to  FIGS. 7A and 7B ,  FIG. 7A  is a schematic diagram illustrating a first type of the resilient portion of the invention, and  FIG. 7B  is a schematic diagram illustrating a second type of the resilient portion of the invention. The resilient portion  232  of the conducting layer  2 A is curved and  FIG. 7A  only shows one embodiment of the invention. As shown in  FIG. 7A , the resilient portions  232  may be curved in the same direction. As shown in  FIG. 7B , the resilient portions  232  may be curved in different directions. The type of the resilient portion  232  can be adjusted according to the force applied to the contact tip. Accordingly, the resilient portion  232  can support great force and acting force without deformation. 
         [0032]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.