Patent Publication Number: US-6336815-B1

Title: Connector for sending power to an IC-chip thru two pressed joints in series

Description:
The present invention, as identified by the above title and docket number, is related to another invention which is identified as follows: “CONNECTOR FOR SENDING POWER TO AN IC-CHIP THRU FOUR PRESSED JOINTS IN SERIES” having U.S. Ser. No. 09/686,049. Patent applications on both of these inventions were filed concurrently on Oct. 11, 2000; and they have one common Detailed Description. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to the structure of power connectors which carry electric current from a power source on one module, thru passed joints with the connector, to the power input terminal in an integrated circuit chip (IC-chip) on another module. 
     Throughout the history of the IC-chip industry, the number of transistors which have been integrated into a single IC-chip has steadily increased; and consequently, the amount of current which is needed to supply power to the IC-chip has also steadily increased. Today, a typical CMOS microprocessor IC-chip requires a power source which can supply about fifty amps; and, the projections are that in a few years, a typical microprocessor IC-chip will require a power source which can supply about one-hundred-fifty amps. 
     In the prior art, a common practice is to attach the IC-chip to one module and send electrical power to the IC-chip from a power source which is on another separate module. This is done, for example, in test equipment which sequentially tests a large number of IC-chips that are mass produced. There a printed circuit board is provided which holds several of the IC-chips that are to be tested; and this printed circuit board is sequentially connected and disconnected to the test equipment thru a power connector and a signal connector. The power connector carries current from a power source to the IC-chips on the printed circuit board while the signal connector carries test signals to and from those IC-chips. 
     Conventionally, the power connector is a “pin and socket” type of connector. In this type of connector, the “pin” is a solid metal cylinder with a typical length of about one inch and a typical diameter of about one-half inch; and, the “socket” is a metal member that has cylindrical shaped hole into which the pin snugly fits. 
     However, a problem with the pin and socket type of connector is that each time a connection is to be made, the pin must be perfectly aligned with the hole in the socket. If the pin is out of line with the socket hole, then the pin will hit the socket when they are moved together; and damage to the connector and/or the two modules can occur. This damage can be quite extensive where the two modules are moved together automatically by mechanism which are motor driven. To avoid such damage, various alignment mechanisms can be employed; however, any alignment mechanism adds to the cost of the overall system. 
     Also in the prior art, a “fuzz button” type of connector has been disclosed which avoids the alignment problem of the pin and socket type of connector. A fuzz button consists of a thin strand of wire which has been wadded up into the shape of a button. In a fuzz button type of connector, the fuzz button is held in a hole on a flat surface of the connector, and a portion of the fuzz button protrudes from the hole past the flat surface. This connector is attached to one module; a flat metal contact pad is provided on the other module; and a connection is made between the two modules by pressing the portion of the fuzz button which protrudes from the hole against the flat contact pad. Here, the fuzz button need not be perfectly aligned with the contact pad. 
     However, one problem with the fuzz button type of connector is that the hole which holds the fuzz button must always be kept in an upright position. Otherwise, the fuzz button can fall out of the hole and thereby make the connector inoperable. Thus the fuzz button is not suitable for use in a printed circuit board which holds several IC-chips that are to be tested, and which is manually handled with various orientations as it is repeatedly connected and disconnected to the test equipment. 
     Also, another problem with the fuzz button is that its thin strand of wire has a current carrying capacity of only about one amp. Thus, to carry fifty to one-hundred fifty amps of current to the power input of an IC-chip, a connector which holds a large number of fuzz buttons should be required. However, that presents a reliability problem because as the number of fuzz buttons in a connector increases, the probability of one or more fuzz buttons falling out of their respective hole increases. 
     Accordingly, a primary object of the present invention is to provide a connector for sending current to the power input of an IC-chip by which all of the above described problems are avoided. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with the present invention, a connector for sending power from a power source on one module to an IC-chip on another module is comprised of: 1) a solid block having a top surface, a bottom surface, and a side with a slot that extends from the top surface to the bottom surface; and 2) a springy strip of metal having a center section which is held by the slot in the block. This springy strip also has a first end section which extends from the center section and includes a springy input contact that is cantilevered above the top surface of the block. Also, the springy strip has a second end section which extends from the center section and includes a springy output contact that is cantilevered below the bottom surface of the block. 
     To transfer electrical power from the power source thru the connector to the IC-chip, two pressed joints are made. The first pressed joint occurs between the springy input contact on the metal strip and a flat metal power pad which is provided on the module that holds the power source to receive current from that power source. The second pressed joint occurs between the springy output contact on the metal strip and a flat metal power pad which is provided on the module that holds the IC-chip to send current to that IC-chip. 
     One desirable attribute of the above connector is that a connection is made between the springy input contact and its corresponding power pad even when they are not perfectly aligned. Similarly, a connection is made between the springy output contact and its corresponding power pad even when they are not perfectly aligned. Also, the above connector remains operable in any orientation because the springy strip of metal is held firmly in the slot of the connector block. Further, the above connector is capable of carrying a current of fifty to one-hundred-fifty amps. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 shows a connector which is one preferred embodiment of the present invention. 
     FIG. 2 shows a subassembly in which the connector of FIG. 1 receives electrical power from a power source. 
     FIG. 3 shows an assembly in which electrical power is sent from the connector in the subassembly of FIG. 2 to an IC-chip. 
     FIG. 4 shows how contact resistance thru the connector of FIGS. 1-3 varies as a function of force. 
     FIG. 5 shows a first modification to the connector in FIGS. 1-3. 
     FIG. 6 shows a second modification to the connector in FIGS. 1-3. 
     FIG. 7 shows a third modification to the connector in FIGS. 1-3. 
     FIG. 8 shows a fourth modification to the connector in FIGS. 1-3. 
     FIG. 9 shows a connector which is a second preferred embodiment of the present invention. 
     FIG. 10 shows a top view of a springy contact which occurs twice in the connector of FIG.  9 . 
     FIG. 11 shows a sectional view, taken along lines A—A, of the springy contact in FIG.  10 . 
     FIG. 12 shows a subassembly in which the connector of FIG. 9 receives electrical power from a power source; and, it also shows how power is sent from the subassembly to an IC-chip. 
     FIG. 13 shows how contact resistance thru the connector of FIGS. 9-12 varies as a function of force. 
    
    
     DETAILED DESCRIPTION 
     A connector  1 , which is one preferred embodiment of the present invention, will now be described in detail with reference to FIG.  1 . This connector  1  is comprised of an electrically insulative block  10  and a springy strip of metal  11 . Block  10  has several structural features which are identified by reference numerals  10   a,    10   a - 1 ,  10   a - 2 ,  10   b,    10   b - 1 ,  10   b - 2 ,  10   c,    10   d,    10   e,    10   e - 1 ,  10   f,    10   f - 1 , and  10   g;  and those features are described below in TABLE 1. Similarly, the springy strip of metal has several structural features which are identified by reference numerals  11   a,    11   b,    11   b - 1 ,  11   c,  and  11   c - 1 ; and those features are also described below in TABLE 1. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Structural Feature 
                 Description 
               
               
                   
                   
               
             
            
               
                   
                 10a, 10a-1, 10a-2 
                 Feature 10a is the top surface of the 
               
               
                   
                   
                 block 10, and this top surface has 
               
               
                   
                   
                 two separate regions 10a-1 and 10a-2. 
               
               
                   
                   
                 Region 10a-1 is a flat central 
               
               
                   
                   
                 region of the surface 10a. Region 
               
               
                   
                   
                 10a-2 surrounds the central region 
               
               
                   
                   
                 10a-1 on three sides and lies above 
               
               
                   
                   
                 that central region. 
               
               
                   
                 10b, 10b-1, 10b-2 
                 Feature 10b is the bottom surface of 
               
               
                   
                   
                 the block 10, and this bottom surface 
               
               
                   
                   
                 has two separate regions 10b-1 and 
               
               
                   
                   
                 10b-2. Region 10b-1 is a flat 
               
               
                   
                   
                 central region of the surface 10b. 
               
               
                   
                   
                 Region 10b-2 surrounds the central 
               
               
                   
                   
                 region 10b-1 on three sides and lies 
               
               
                   
                   
                 below that central region. 
               
               
                   
                 10c 
                 Feature 10c is one side of the block 
               
               
                   
                   
                 10. 
               
               
                   
                 10d 
                 Feature 10d is another side of the 
               
               
                   
                   
                 block 10 which is opposite the side 
               
               
                   
                   
                 10c. 
               
               
                   
                 10e, 10e-1 
                 Feature 10e is one end of the block 
               
               
                   
                   
                 10. This end 10e has a step 10e-1. 
               
               
                   
                 10f, 10f-1 
                 Feature 10f is one end of the block 
               
               
                   
                   
                 10 which is opposite to the end 10e. 
               
               
                   
                   
                 This end 10f has a step 10f-1. 
               
               
                   
                 10g 
                 Feature 10g is a slot in side 10c of 
               
               
                   
                   
                 the block 10. This slot 10c extends 
               
               
                   
                   
                 from the central region 10a-1 of the 
               
               
                   
                   
                 top surface 10a to the central region 
               
               
                   
                   
                 10b-1 of the bottom surface 10b. 
               
               
                   
                 11a 
                 Feature 11a is a flat central section 
               
               
                   
                   
                 of the springy metal strip 11. This 
               
               
                   
                   
                 section 11a is held in the slot 10g 
               
               
                   
                   
                 of the block 10. 
               
               
                   
                 11b, 11b-1 
                 Feature 11b is a first end section of 
               
               
                   
                   
                 the metal strip 11 which extends from 
               
               
                   
                   
                 the central section 11a. This first 
               
               
                   
                   
                 end section 11b includes a springy 
               
               
                   
                   
                 arch-shaped input contact 11b-1 which 
               
               
                   
                   
                 is cantilevered over the flat central 
               
               
                   
                   
                 region 10a-1 of the block 10. 
               
               
                   
                 11c, 11c-1 
                 Feature 11c is a second end section 
               
               
                   
                   
                 of the metal strip 11 which extends 
               
               
                   
                   
                 from the central section 11a. This 
               
               
                   
                   
                 second end section 11c includes a 
               
               
                   
                   
                 springy arch-shaped output contact 
               
               
                   
                   
                 11c-1 which is cantilevered under the 
               
               
                   
                   
                 flat central region 10b-1 of the 
               
               
                   
                   
                 block 10. 
               
               
                   
                   
               
            
           
         
       
     
     How the connector  1  is combined with several other components to form a subassembly that receives electrical power from a power source, will now be described with reference to FIG.  2 . In the FIG. 2 subassembly, the connector  1  is attached as shown to a printed circuit board  20  by a bracket  21  and a pair of screws  22   a  and  22   b.  Bracket  21  holds the connector block  10  such that the springy input contact  11   b - 1  is compressed against a flat metal power pad  23  on the printed circuit board  20 . 
     Bracket  21  completely surrounds and loosely touches the connector  1  on its two sides  10   c  and  10   d  and two ends  10   e  and  10   f.  Thus the connector can move in the bracket  21  perpendicular to the printed circuit board  20 . The portion of bracket  21  which touch the two connector ends  10   e  and  10   f  have respective steps  21   a  and  21   b,  and the compressed springy input contact  11   b - 1  urges block  10  away from the printed circuit board  20  until the steps  21   a  and  21   b  engage the steps  10   e - 1  and  10   f - 1  on the block. When the steps  21   a,    21   b,    10   e - 1 , and  10   f - 1  are engaged, a gap  24  occurs between the printed circuit board  20  and region  10   a - 2  on the top surface of the connector block  10 . 
     Also attached to the printed circuit board  20  is a DC—DC electrical power converter  25 . This power converter  25  has an input terminal (not shown) which receives DC electrical at one voltage, and it has an output terminal  25   a  on which DC power is generated at another voltage. Power from the output terminal  25   a  is sent on a conductor  25  thru the power pad  23  to the input contact  11   b - 1  of the connector  1 . 
     Referring now to FIG. 3, it shows how the subassembly of FIG. 2 is incorporated into a larger assembly to transfer electrical power to an IC-chip  30 . In the assembly of FIG. 3, the IC-chip  30  is held by a socket  31  which is attached to a printed circuit board  32 . A flat metal power pad  33  is provided on the printed circuit board  32 , and a conductor  34  carries power from the pad  33  to the IC-chip  30 . 
     To send electrical power to the power pad  33 , that power pad is pressed against the output contact  11   c - 1  of the connector  1 . When such pressing occurs, the force which is exerted by the power pad  33  is opposed by both the springy input contact  11   b - 1  and the springy output contact  11   c - 1 . Consequently, both of the contacts  11   b - 1  and  11   c - 1  get compressed; and that causes the steps  10   e - 1  and  10   f - 1  to move away from the steps  21   a  and  21   b.  Thus in FIG. 3, the steps  10   e - 1  and  10   f - 1  are separated from the steps  21   a  and  21   b,  and the connector block  10  “floats” between the two printed circuit boards  20  and  32 . 
     One desirable attribute of the above described connector  1  is that it has a low contact resistance. Consequently, the connector  1  is suitable for use in making a power connection which carries a large current without causing a large voltage drop across the connector. 
     Text results which show the contact resistance of one actual connector  1  are illustrated in FIG.  4 . In that particular connector, the input contact  10   b - 1  and the output contact  10   c - 1  were each 0.546 inches by 0.320 inches. Contact resistance (CR) for the connector as shown in FIG. 4, is the resistance thru the pressed joint between the input contact  11   b - 1  and pad  23  plus the resistance thru the pressed joint between the output contact  11   c - 1  and pad  33 . Force on the horizontal axis as shown in FIG. 4 is the force with which pad  33  presses against the output contact  11   c - 1 . 
     Inspection of FIG. 4 shows that the contact resistance reaches a minimum value of about one-half milliohm when the force between pad  33  and the output contact  11   c - 1  is three and one-half pounds. If the force is increased any further, the contact resistance stays nearly constant because it is limited by the size of the contact area in each pressed joint. To lower the minimum contact resistance, the size of the input contact  11   b - 1  and the output contact  11   c - 1  and their corresponding power pads need to be increased. 
     Another desirable attribute of the above described connector  1  is that the input contact  11   b - 1  and the output contact  11   c - 1  are protected from being overstressed while the power pad  33  is pressed against the output contact. Protection for the input contact  11   b - 1  occurs due to the fact that the input contact is surrounded on three sides by region  10   a - 2  of connector block  10 . Protection for the output contact  11   c - 1  occurs due to the fact that the output contact is surrounded on three sides by region  10   b - 2  of the connector block  10 . 
     Still another desirable attribute of the above described connector  1  is that the output contact  11   c - 1  and the power pad  33  do not need to be perfectly aligned in order for a connection to occur between them. This is important in a mass production environment where it is expensive and/or impractical to perfectly align the output contact  11   c - 1  with the power pad  33  each time the assembly of FIG. 3 is replicated. By comparison, when a connection is made between a pin and a socket, the pin must be in perfect alignment with the socket, or else the pin will not fit into the socket. 
     Yet another desirable attribute of the above described connector  1  is the ease with which it can be manufactured. To begin, the connector block  10  and the springy metal strip  11  are separately produced. Next, the center section  11   a  of the springy metal strip  11  is simply inserted into slot  10   g  of the connector block  10 . Then, to attach the connector  1  to the printed circuit board  20 , the connector  1  is simply placed in the socket  21  which in turn is screwed onto the printed circuit board. 
     A connector  1 , which constitutes one preferred embodiment of the present invention, has now been described in detail. Also, a subassembly has been described in detail in which the connector  1  receives electrical power from a DC—DC power converter; and, a larger assembly has been described in detail in which the connector  1  transfers electrical power to an IC-chip. Now, various changes and modifications which can be made to the above details will be described. 
     As a first modification, the springy strip of metal  11  in FIGS. 1-3 is replaced with another springy strip of metal  41  as shown in FIG.  5 . This metal strip  41  has a flat central section  41   a,  a first end section  41   b  which extends from the central section as shown, and a second end section  41   c  which extends from the central section as shown. The first end section  41   b  includes a springy input contact  41   b - 1  which has multiple arches. Similarly, the second end section  41   c  includes a springy output contact  41   c - 1  which has multiple arches. Each arch in the input contact  41   b - 1  makes contact with the power pad  23  in the FIG. 3 assembly; and each arch in the output contact  41   c - 1  makes contact with the power pad  33  in the FIG. 3 assembly. 
     As a second modification, the springy strip of metal  11 FIGS. 1-3 is replaced with another springy strip of metal  51  as shown in FIG.  6 . This metal strip  51  has a flat central section  51   a,  a first end section  51   b  which extends from the central section, and a second and section  51   c  which extends from the central section. The first end section  51   b  and the second end section  51   c  bend as shown in only one direction away from the central section  51   a.  This is in comparison to the springy strip of metal in FIG. 1 wherein the end section  11   b  and  11   c  bend at a right angle away from the central section  11   a  and thereafter bend in an opposite direction back towards the central section. 
     As a third modification, the springy strip of metal  11  in FIGS. 1-3 is replaced with another springy strip of metal  61  as shown in FIG.  7 . This metal strip  61  has a flat central section  61   a,  a first end section  61   b  which extends from the central section, and a second end section  61   c  which extends from the central section. Each end section  61   b  and  61   c  is straight, as shown. By comparison, each end section  51   b  and  51   c  in FIG. 6 is bent into a single arch. 
     As a fourth modification, the connector block  10  in FIGS. 1-3 is replaced with another connector block  70  as shown in FIG.  8 . This connector block  70  is the same as the connector block  10  except that it has it has multiple slots  70   g  instead of just a single slot  10   g.  In FIG. 8, the connector block  70  is shown as having four slots  70   g  as an example. Each slot  70   g  is used to hold the central section of any one of the springy metal strips  11 ,  41 ,  51 , or  61 . Thus when the connector block  70  is incorporated into the assembly of FIG. 3, it holds four of the springy metal strips  11 ,  41 ,  51 , or  61  against the power pad  23  and the power pad  33 . 
     As a fifth modification, the connector block  10  in FIGS. 1-3, as well as the connector block  70  in FIG. 8, can be made of an electrically conductive material, such as aluminum. With that modification, the path which the current takes from the input contact  11   b  to the output contact  11   c - 1  will be shortened by the conductive connector block itself. By comparison, when the connector block  10  in FIGS. 1-3 and the connector block  70  in FIG. 8 are made of a non-conductive material such as plastic, the cost of manufacturing the block is minimized. 
     Next, with reference to FIG. 9, a connector  81 , which is second preferred embodiment of the present invention, will be described in detail. This connector  81  is comprised of an electrically conductive block  90  and a pair of springy contacts  91  and  92 . Several structural features of the conductive block  90  are identified in FIG. 9 by reference numerals  90   a,    90   a - 1 ,  90   a - 2 ,  90   a - 3 ,  90   a - 4 ,  90   b,    90   b - 1 ,  90   b - 2 ,  90   b - 3 ,  90   b - 4 ,  90   c,    90   e,    90   e - 1 ,  90   f  and  90   f - 1 ; and those structural features are described below in TABLE 2. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Structural Feature 
                 Description 
               
               
                   
                   
               
             
            
               
                   
                 90a, 90a-1, 90a-2 
                 Feature 90a is the top surface of the 
               
               
                   
                   
                 block 90, and this top surface has 
               
               
                   
                   
                 two separate regions 90a-1 and 90a-2. 
               
               
                   
                   
                 Region 90a-1 is a central region of 
               
               
                   
                   
                 the top surface 90a. Region 90a-2 
               
               
                   
                   
                 borders the central region 90a-1 on 
               
               
                   
                   
                 two sides and lies above that region. 
               
               
                   
                 90a-3, 90a-4 
                 Features 90a-3 and 90a-4 are a pair 
               
               
                   
                   
                 of channels which are spaced apart in 
               
               
                   
                   
                 the central region 90a-1 of the top 
               
               
                   
                   
                 surface of block 90. 
               
               
                   
                 90b, 90b-1, 90b-2 
                 Features 90b is the bottom surface of 
               
               
                   
                   
                 the block 90, and this bottom surface 
               
               
                   
                   
                 has two separate regions 90b-1 and 
               
               
                   
                   
                 90b-2. Region 90b-1 is a central 
               
               
                   
                   
                 region of the bottom surface 90b. 
               
               
                   
                   
                 Region 90b-2 borders the central 
               
               
                   
                   
                 region 90b-1 on two sides and lies 
               
               
                   
                   
                 below that region. 
               
               
                   
                 90b-3, 90b-4 
                 Features 90b-3 and 90b-4 are a pair 
               
               
                   
                   
                 of channels which are spaced apart in 
               
               
                   
                   
                 the central region 90b-1 of the 
               
               
                   
                   
                 bottom surface of block 90. 
               
               
                   
                 90c 
                 Feature 90c is one side of the block 
               
               
                   
                   
                 90. Block 90 also has an opposite 
               
               
                   
                   
                 side which is hidden from view in 
               
               
                   
                   
                 FIG. 9. This opposite side has the 
               
               
                   
                   
                 same shape as side 90c and is 
               
               
                   
                   
                 parallel to side 90c. 
               
               
                   
                 90e, 90e-1 
                 Feature 90e is one end of the block 
               
               
                   
                   
                 90. This end 90e has a step 90e-1. 
               
               
                   
                 90f, 90f-1 
                 Feature 90f is one end of the block 
               
               
                   
                   
                 90 which is opposite to the end 90e. 
               
               
                   
                   
                 This end 90f has a step 90f-1. 
               
               
                   
                   
               
            
           
         
       
     
     In the connector  81  of FIG. 9, the springy contact  91  is held as shown against the central region  90   a - 1  of the top surface of the conductive block  90  by the pair of channels  90   a - 3  and  90   a - 4 . Similarly, in the connector  81  of FIG. 9, the springy contact  92  is held as shown against the central region  90   b - 1  of the bottom surface of the conductive block  90  by the pair of channels  90   b - 3  and  90   b - 4 . Each springy contact  91  and  92  has the same structural features; and those features are shown in detail of FIGS. 10 and 11. 
     Each springy contact  91  and  92  has two spaced apart end sections  93   a  and  93   b  which are connected to a center section  94 . This center section  94  is comprised of a selectable number of torsion springs  95  which lie in parallel to each other. In FIG. 10, a total of three torsion springs  95  are shown as just one example. 
     Each torsion spring  95  consists of a single strip of metal which is substantially flat. In the connector  81 , the strip of metal is held by the end sections  93   a  and  93   b  at an acute angle relative to region  90   a - 1  or region  90   b - 1  of the conductive block  90 . Thus in the connector  81 , only one edge of the metal strip in each torsion spring  95  contacts the top surface  90   a  or the bottom surface  90   b  of block  90 . The opposite edge of the metal strip in each torsion spring  95  provides a contact to an external power pad which sends power to the connector  81  or receives power from the connector. 
     How the connector  81  is combined with other components to form a subassembly  100 , that receives electrical power from a power source, will now be described with reference to FIG.  12 . In the subassembly  100 , the other components with which the connector  81  is combined are the same components with which the previously described connector  1  is combined in FIG.  2 . Those components are a printed circuit board  20 , a bracket  21 , a pair of screws  22   a  and  22   b,  a power pad  23 , a DC—DC power converter  25 , and a conductor  26 . 
     In the assembly  100 , power from the DC—DC converter  25  is sent on output terminal  25   a  thru conductor  26  to the power pad  23 . Each torsion spring  95  in the springy contact  91  is twisted between the power pad  93  and region  90   a - 1  of the conductive block  90 . Thus, each torsion spring  95  in the springy contact  91  forms one pressed joint with the power pad  93  and another pressed joint with region  90   a - 1  of block  90 . Thru those pressed joints, power is transferred from the power pad  23  to the conductive block  90 . 
     How the subassembly  100  is used to transfer electrical power to an IC-chip is also illustrated in FIG.  12 . There, the IC-chip is identified by reference numeral  30 ; and it is held by a socket  31  which is attached to a printed circuit board  32 . A flat metal power pad  33  is provided on the printed circuit board  32 , and a conductor  34  connects the power pad  33  to the IC-chip  30 . All of the components  30 - 34  are the same as were previously described in conjunction with FIG.  3 . 
     To send electrical power to the power pad  33 , that power pad is pressed against the springy contact  92  of the connector  81  in the subassembly  100 . When such pressing occurs, the force which is exerted by the power pad  33  is opposed by each torsion spring  95  in the springy contact  92  and each torsion spring  95  in the springy contact  91 . Consequently, all of those torsion springs twist; and that causes the steps  90   e - 1  and  90   f - 1  to move away from the steps  21   a  and  21   b.  Thus, the connector block  90  “floats” between the two printed circuit boards  20  and  32 . 
     When the power pad  33  is pressed against the springy contact  92  as described above, each torsion spring  95  in the springy contact  92  forms one pressed joint with the power pad  33  and another pressed joint with region  90   b - 1  of block  90 . At the same time, each torsion spring  95  in the springy contact  91  forms one pressed joint with the power pad  23  and another pressed joint with region  90   a - 1  of block  90 . Through all of those pressed joints, electrical power is transferred from the power pad  23  to the power pad  33 , and from there, to the IC-chip  30 . 
     With the connector  81  of FIGS. 9-12, a low contact resistance is obtained because current passes in parallel thru all of the torsion springs  95  in the springy contact  91 , and current passes in parallel thru all of the torsion springs  95  in the springy contact  92 . Also with the connector  81  of FIGS. 9-12, all of the torsion springs  95  are protected from being overstressed because the regions  90 - 1 ,  90   a - 2 ,  90   b - 1  and  90   b - 2  of the connector block  90  limit how much the torsion springs  95  can be twisted. 
     Further with the connector  81  of FIG. 9-12, the springy contact  92  and the power pad  93  do not need to be perfectly aligned in order for a connection to occur between them, and thus the connector is suitable for use in a mass production environment. Also the connector  81  of FIGS. 9-12 is easily manufactured. To begin, the connector block  90  and the springy contacts  91  and  92  are separately produced. Then, to assemble to the connector  81 , the ends  93   a  and  93   b  of contact  91  are simply slid into the channels  90   a - 3  and  90   a - 4  on the connector block  90 ; and, the ends  93   a  and  93   b  of contact  92  are simply slid into the channels  90   b - 3  and  90   b - 4  of the connector block  90 . 
     Test results which show the contact resistance of one actual connector  81  are illustrated in FIG.  13 . For that particular connector, each torsion spring  95  is 0.700 inches long, 0.150 inches wide at its center, and 0.055 inches wide at its ends. Also for that particular connector, the springy input contact  91  and the springy output contact  92  each included a total of three of the torsion springs  95 . Contact resistance (CR) for the connector, as shown in FIG. 13, is the resistance thru the pressed joints which couple the input power pad  23  to the connector block  90  plus the resistance thru the pressed joints which coupled the output power pad  33  to the connector block  90 . Force on the horizontal axis in FIG. 13 is the force with which the power pad  33  presses against the springy output contact  92 . 
     Two connectors, which constitute two preferred embodiments of the present invention, have now been described in detail, along with subassemblies and assemblies in which those connectors are used, and along with several modifications to the connectors themselves. Accordingly, it is to be understood that the present invention is not limited to the details of any one particular connector, subassembly, assembly, or modification, but is defined by the appended claims.