Abstract:
Methods and apparatus disclosed for providing a fastener that can hold suitably flat planar objects. No tools are required to actuate the fastener. The fastener holds the object with a predetermined range of force, determined by a built-in spring when actuated. The fastener is particularly suited for fastening Printed Wiring Boards (PWBs) in an electronics enclosure, and holds the PWBs in position, as well as providing electrical coupling of a voltage supply used on the PWB to the electronic enclosure.

Description:
FIELD OF THE INVENTION 
     The present invention relates to fastening mechanisms. In particular, the current invention is well suited for fastening printed wiring boards (PWBs) to mounting posts that are then attached to a frame of an electronic enclosure, or to another PWB. 
     DESCRIPTION OF RELATED ART 
     Modern electronic systems, in particular, computer systems, comprise one or more processors, controllers, memory, and input/output devices such as floppy disk drives, hard disk drives, compact disk drives, for examples. Electronic circuitry, logic elements, and memory circuitry implementing the parts of an electronic system are constructed on silicon, or other suitable semiconductor, chips. The chips are typically mounted on modules that couple signals and power supply connections from the chip to connection points, or ports, on the modules. Historically, wire bonds have frequently been used to couple signals and power from a chip to electrical conductors on the module, the electrical conductors thereby continuing the electrical continuity to the ports on the module. A more recent means to couple signals and power from a chip to electrical conductors on the module is accomplished with solder ball connections. The chip with solder balls attached is placed upon a module, with the solder balls being in contact with electrical conductors on the module. The combined unit is heated to a temperature at which the solder ball connections melt, completing the electrical chip/module interconnection. Upon cooling the combined unit, the solder re-hardens, making a good mechanical connection, as well as the electrical interconnection. The modules are mounted on, and further interconnected by, printed wiring boards (PWBs). There are a number of techniques that are used to couple signal and power between a module and a PWB. One such technique is to place connecting pins on the module, the connecting pins being coupled to the signal and power conductors on the module. Often, the pins are brazed or soldered on the bottom of the module. The module is placed on the PWB with the pins inserted into holes in the PWB. The holes are plated with electrically conducting material that is coupled to conductors on one or more layers of patterned, electrically conducting, material in the PWB. The PWBs have signal wiring on one or more electrically conducting layers that couple signals between the various module ports, as well as to connectors from which signals and power conductors are routed to other places in the computer system. 
     The electronic system also comprises an enclosure inside which the PWBs, power supplies, and other components are housed. The enclosure can be made of any suitable material, such as plastic or metal. Metal is commonly used for the enclosure in order that a system (chassis) voltage (commonly ground) can be coupled to a voltage used on the PWBs (commonly ground) to supply power to circuitry on the semiconductor chips. For most systems, coupling ground used by circuitry on the semiconductor chips to chassis ground provides a short return path for common mode current. 
     The PWBs must be held in their proper place in the enclosure. A traditional method of mounting PWBs in computer system enclosures and support structures has been the use of threaded fasteners, such as screws and bolts. While this method does provide secure holding of the PWB in position, and also provides positive electrical contact, it does present several problems as discussed below. 
     First, the assembly of these threaded fasteners can be time consuming and often requires the use of tools. Torque must be carefully controlled to prevent damaging the PWB. 
     Second, the use of such threaded fasteners affects the packaging design and can cause compromising the design by requiring sufficient clearances for the tools and drivers needed to secure the threaded fasteners. 
     Third, during field repairs, the fastener may be difficult to access. The fasteners may be dropped into the interior of the enclosure and cause damage if not retrieved. Proper torque settings may be difficult to control during field repairs, raising the likelihood of the field repairs causing further damage to the product. 
     Some electronic products require a first PWB to be mounted to a second PWB. The disclosed fastener is capable of fastening the first PWB to the second PWB. The second PWB can then further be mounted to the enclosure by additional uses of the disclosed fasteners. 
     Therefore, there is a need for a fastener that can quickly and reliably connect a PWB mechanically and electrically to an enclosure, or to another PWB, without the use of tools. 
     SUMMARY OF THE INVENTION 
     The present invention discloses a fastener that can fasten and hold a substantially flat, planar, object to the fastener within a predetermined range of force, providing reliable electrical connection between the object and fastener, without the use of tools. 
     In an embodiment, the fastener connects a printed wiring board (PWB) to an enclosure. 
     In an embodiment, the fastener connects a first PWB to a second PWB. 
     In an embodiment, a clamp lever comprises a built-in spring that maintains a predetermined range of force between the PWB and the mounting post. 
     In an embodiment, the clamp lever is connected with a pin to the mounting post, allowing the clamp lever to be pivoted from a first position, substantially longitudinal with the axis of the mounting post, to a second position, substantially orthogonal to the axis of the mounting post. The action of pivoting the clamp lever deforms the built-in spring, compressing the PWB against a shoulder on the mounting post. The deformation of the built-in spring places a predetermined range of force between the PWB and the shoulder of the mounting post even considering normal process variations in the thickness of the PWB. 
     In an embodiment, the mounting post is constructed of a conducting material, such as metal. The action of pivoting the clamp lever and compressing the built-in spring creates an electrical connection between an electrically conductive area on the PWB and the mounting post. Advantageously, the mounting post is further electrically coupled to a chassis of the computer enclosure, thus allowing reliable coupling between a supply voltage used in semiconductor chips in the computer system and the computer enclosure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an exploded view of the fastener of the current invention together with the Printed Wiring Board (PWB) that is being fastened. 
     FIG. 2 shows a view of the fastener of the current invention being inserted through a keyhole slot in the PWB. 
     FIG. 3 shows a view of the fastener of the current invention placed in a narrow portion of the keyhole slot in the PWB. 
     FIG. 4 shows a view of the fastener of the current invention placed in the narrow portion of the keyhole slot in the PWB, with the fastener actuated to clamp the PWB. 
     FIG. 5A shows a side view of the fastener near the side of the narrow portion of the keyhole slot in the PWB. 
     FIG. 5B shows a detailed side view of the fastener after actuation. 
     FIG. 5C shows a cutaway side view of a portion of the fastener after actuation, seen as turned 90 degrees from the views of FIGS. 5A and 5B. 
     FIG. 5D shows a side view of a clamp lever designed to stay clamped when jarred. 
     FIG. 5E shows another clamp lever designed to stay clamped when jarred. 
     FIG. 5F shows another clamp lever designed to stay clamped when jarred. 
     FIG. 6A shows a bottom portion of a mounting post of the fastener, attached to an enclosure by means of a screw threaded through the enclosure and into a tapped hole in the mounting post. 
     FIG. 6B shows a bottom portion of a mounting post of the fastener, comprising a screw that is part of the mounting post, the screw being threaded into the enclosure. 
     FIG. 6C shows a bottom portion of a mounting post of the fastener, comprising a sheet metal screw extension that is part of the mounting post. 
     FIGS. 7A-7D show several embodiments of pin retention techniques. 
     FIGS. 8A-8B show several embodiments of the standoff. 
     FIGS. 9A-9B show roughened surfaces on the clamping ring and a shoulder on the mounting post. 
     FIG. 10A shows an embodiment of a mounting post suitable for having two clamp levers. 
     FIG. 10B shows two objects clamped to the mounting post of FIG.  10 A. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Having reference now to the figures, the invention will now be described in detail. 
     Referring to FIG. 1, a Printed Wiring Board (PWB)  7  is to be fastened to mounting post  11 . Although PWBs are used for exemplary purposes, the invention contemplates any substantially flat, planar object that needs to be fastened to mounting posts  11 . Furthermore, the object only needs to be substantially flat and planar in the immediate vicinity of the clamp. 
     PWB  7  has one or more keyhole slots  8  which are openings in PWB  7 . FIG. 1 shows one such keyhole slot  8  for simplicity. Most applications would have a number of keyhole slots  8  on PWB  7 , for fastening to a number of mounting posts. Keyhole slot  8  comprises a larger portion  9  and a smaller portion  10 . 
     Mounting post  11  comprises a substantially cylindrical standoff  12 ; a first shoulder  5 ; a substantially cylindrical section  17  that is coaxial with standoff  12  but which has a smaller diameter than standoff  12 ; a second shoulder  15 ; and a substantially cylindrical section  16  that is also coaxial with standoff  12 . An optional chamfered section  14  can be used to reduce the diameter of standoff  12  to a smaller diameter of first shoulder  5 . Cylindrical section  16  has a hole  18  going completely through cylindrical section  16 . 
     Note that whereas standoff  12  is advantageously substantially cylindrical in many embodiments, standoff  12  can be formed in alternative shapes, such as, for examples, hexagonally or octagonally along its axis for ease of gripping or turning in some embodiments described later, and as shown in FIGS. 8A and 8B. 
     Clamping ring  6 , which will be described in more detail later, is coaxially and slideably placed over cylindrical section  16 . Inner diameter I of clamping ring  6  is smaller than the diameter of cylindrical portion  17 , which prevents clamping ring  6  from moving over cylindrical portion  17 . 
     Clamp lever  2 , also described in more detail later, is shaped such that clamping lever  2  can be pivotally attached to cylindrical portion  16  by means of a pin  4  that passes through holes  3  in clamping lever  2  and hole  18  in cylindrical section  16 . The remaining elements shown in the expanded view of clamp lever  2  shown in FIG. 1 will be explained in more detail later. 
     FIG. 2 shows PWB  7  being lowered onto the fastener. Clamp lever  2  and clamping ring  6  are small enough diameter as to pass freely through the larger portion  9  of keyhole slot  8 . Although FIG. 2 shows PWB  7  being lowered onto the fastener, those skilled in the art will understand that motion of PWB  7  relative to the fastener is of importance. For example, the fastener could be moved into portion  9  of keyhole slot  8 . 
     FIG. 3 shows PWB  7  being moved horizontally such that cylindrical portion  17  (not viewable in this drawing) and a portion of cylindrical portion  16  (not viewable in this drawing) extend through smaller portion  10  (not viewable in this drawing) of keyhole slot  8 . In this position, a portion of clamping ring  6  and some of first shoulder  5  overlap PWB  7 . Again, relative motion between PWB  7  and the fastener is what is intended in the horizontal motion that places cylindrical portion  16  in smaller portion  10 . 
     FIG. 4 shows clamp lever  2  being actuated by being pivoted from being substantially longitudinal with the axis of mounting post  11  to being substantially orthogonal to the axis of mounting post  11 . This actuation will be described below. 
     FIGS. 5A-5F shows the fastener in more detail. 
     Clamp lever  2 , shown in FIG. 5A, and, isometrically in the expanded view shown in FIG. 1, has a spring loaded engaging portion. The spring loaded engaging portion comprises a cutout  20 , a spring element  22 , and a spring edge  21 . Cutout  20  is placed between hole  3  and a spring edge  21 ; spring edge  21  bears upon a top surface  33  of clamping ring  6  when clamp lever  2  is actuated by pivoting around pin  4  which is inserted in hole  3  in clamp lever  2  and also through hole  18  in cylindrical section  16  of mounting post  11 . In the embodiment shown best in the expanded view of clamp lever  2  in FIG. 1, clamp lever  2  has two holes  3 , two cutouts  20 , two spring elements  22 , and two spring edges  21 . Other means to produce spring element  22  are within the spirit of the invention. Furthermore, while pin  4  inserted through holes  3  and  18  is a preferred embodiment, any means that allows clamp lever  2  to pivot is within the scope and spirit of this invention. For example, small cylinders could be brazed to cylindrical section  16 , with holes  3  being placed on such small cylinders. 
     Clamping ring  6  is shown, in FIG. 5A, to rest upon second shoulder  15 , the inner diameter  1  (see FIG. 1; inner diameter  1  is not visible in FIG. 5A) of clamping ring  6  being of smaller diameter than the diameter of cylindrical portion  17  of mounting post  11 . Clamping ring  6  in this position is coaxially and slideably free to move between second shoulder  15  and clamp lever  2 . Clamping ring  6  is shown to comprise chamfer  24 . Standoff  12  is shown comprising chamfer  14 . 
     Inner slot edge  31  is an edge of smaller portion  10  of keyhole slot  8  on PWB  7 . The thickness of PWB  7  is greater than the distance between a bottom surface  13  of clamping ring  6  and a top surface of first shoulder  5 , when clamping ring  6  rests upon second shoulder  15  as described earlier. As PWB  7  is slid horizontally as described above, clamping ring  6  is raised slightly as some of PWB  7  enters the space between the bottom surface  13  of clamping ring  6  and the top surface of first shoulder  5 . Chamfers  24  and  14  facilitate ready movement of PWB  7  between the bottom surface  13  of clamping ring  6  and the top surface of first shoulder  5 . In an embodiment, clamping ring is raised enough to cause some deformation of spring element  21  against a top surface  33  of clamping ring  6 . In another embodiment, the top surface  33  of clamping ring  6  does not contact clamp lever  2  until clamp lever  2  is actuated. 
     In an embodiment, prior to actuation, clamp lever  2  is held in a position substantially longitudinal with the axis of mounting post  11  by friction between pin  4  and hole  3 , as well as friction between pin  4  and hole  18 . In another embodiment, some deformation of spring element  22  exists even when bottom surface  13  of clamping ring  6  rests upon second shoulder  15 , in which case, friction between the top surface  33  of clamping ring  6  and clamp lever  2  holds clamp lever  2  in a position substantially longitudinal with the axis of mounting post  11 . 
     FIG. 5B shows clamp lever  2  actuated. Clamp lever  2  is actuated by pivoting clamp lever  2  around pin  4 , which is inserted through holes  3  in clamp lever  2 , as well as hole  18  in mounting post  11  (hole  18  not visible in FIG.  5 B). As clamp lever  2  is pivoted, spring elements  22  are deformed, causing spring edges  21  to bear downward on the top surface  33  of clamping ring  6 . As shown, pivoting action is stopped when stop edge  36  of clamp lever  2  comes into contact with clamping ring  6 . Clamp lever  2  is thereby stopped from further pivoting before an end  34  of clamp lever  2  can come into contact with PWB  7 . 
     Once actuated, clamp lever  2  remains actuated, held by friction between spring edges  21  and top surface  33  of clamping ring  6 . 
     Several embodiments reduce the likelihood of clamp lever  2  becoming deactuated should the enclosure receive severe impact, such as if it were dropped. 
     In an embodiment, shown in FIG. 5F, spring elements  22  are shaped such that as clamp lever  2  is actuated, force bearing upon surface  33  increases, but then decreases as actuation is completed. Thinning the portion of spring elements  22  in the vicinity of contact (when clamp lever  2  is activated) between spring edges  21  and surface  33  produces this embodiment. As shown, spring element thickness E is less than spring element thickness D, thus requiring increasing force to be applied to cause clamp lever  2  to pivot clockwise in the figure once clamp lever  2  has been actuated. 
     Reducing the radius of curvature between hole  3  and spring edges  21  in the area where spring edges  21  contact surface  33  in the last small amount of actuation also produces this embodiment, and is shown in FIG.  5 D. Radius B is larger than radius C. In this embodiment, increased force would have to act on clamp lever  2  to cause greater deformation of spring elements  22  during a de-actuation of clamp lever  2 . Radius A is less than radius B and also less than radius C. Such latching action is sometimes called “over center” in the literature. 
     In another embodiment, shown in FIG. 5E, that enhances resistance to unintended de-actuation, a slightly flattened section  37  exists on spring edge  21  in the area of spring edge  21  that is in contact with surface  33  when clamp lever  2  is actuated. Again, significant force would have to act on clamp lever  2  to “climb the hill” needed to de-actuate the clamp lever. 
     In yet another embodiment that enhances resistance to unintended deactuation, top surface  33 A is roughened (shown in FIG. 9) to enhance friction between spring edges  21  and surface  33 A. Chemical etching or machining are well-known techniques to roughen a surface. 
     FIG. 5C shows a cutaway view of the fastener holding PWB. This view is turned 90 degrees from the view of  5 B, in order to show more clearly the relationship of clamp lever  2  with pin  4  and hole  18 , as well as to show both spring elements and both cutouts. 
     Pin  4  is inserted in holes  3  of clamp lever  2 , and also hole  18  in cylindrical section  16 , allowing clamp lever  2  to pivot, as described earlier. 
     Cutouts  20  create spring elements  22 , which bear, via spring edges  21 , against top surface  33  of clamp ring  6  when clamp lever  2  is actuated. Spring edges  21  together with their respective spring elements  22  and cutouts  20  are considered together to be an embodiment of a spring loaded engaging portion of clamp lever  2 . As spring edges  21  bear against top surface  33  of clamp ring  6 , clamp ring  6  is forced against PWB  7 , clamping PWB  7  between the bottom surface  13  of clamp ring  6  and the top surface of shoulder  5 . 
     The force with which PWB  7  is clamped is determined by the spring constant of spring elements  22  and the degree of deformation of spring elements  22  as clamp lever  2  is actuated. A very high spring constant will limit the range of PWB thicknesses a particular design will accommodate; a lower spring constant will result in a more compliant spring that will accommodate a wider range in PWB thickness, as well as manufacturing tolerances in the thickness of the PWB. A lower spring constant can be obtained by making spring elements  22  thinner between spring edges  21  and cutouts  20 , or making the material from which clamp lever  2  is constructed thinner or of a less stiff material. Spring elements  22  should be thick enough between spring edges  21  and cutouts  20  so as not to buckle when clamp lever  2  is actuated. 
     PWBs are often designed with electrically conducting material patterned on top and/or bottom surfaces of the PWB. Conductor  32  is shown to be on a top surface of PWB  7 , and conductors  34  are shown to be on a bottom surface of PWB  7 , as shown in FIG.  5 C. Conductors  32  and  34  may be coplanar with the surfaces of PWB  7  as shown, or may rest upon the surfaces of PWB  7 , and therefore extend outwards beyond the surfaces of PWB  7  by up to the thickness of conductors  32  and  34 . Either a conductor coplanar on a surface of PWB  7  or a conductor formed upon a surface of PWB  7  is considered to be a conductor on a surface of PWB  7 . Conductor  32  is an electrical conductor on the top surface of PWB  7 , at or near edge  31  of smaller section  10  of keyhole slot  8 . Advantageously, conductor  32  is routed along substantially the entire top surface of PWB  7  near edge  31 . Conductor  32  is wide enough to make a low resistance electrical coupling between the bottom surface  13  of clamping ring  6  and conductor  32  when clamp lever  2  is actuated. In an embodiment wherein clamping lever  2 , pin  4 , and mounting post  11  are constructed of electrically conducting material, a low resistance path is thereby made between conductor  32  and mounting post  11 . Similarly, conductor  34  is advantageously routed along substantially the entire bottom surface of PWB  7  near edge  31 . Conductor  34  is wide enough to make a low resistance electrical coupling between shoulder  5  and conductor  34 . In an embodiment wherein mounting post  11  is constructed of electrically conducting material, mounting post  11  is thus electrically coupled to conductor  34  upon actuation of the fastener. As stated earlier, it is often desirable to couple an electrical supply voltage, usually ground, on the PWB to the chassis of the electrical enclosure. A low resistance coupling between bottom surface  13  of clamping ring  6  and conductor  32  is enhanced by suitably roughening bottom surface  13 , shown as surface  13 A in FIG.  9 A. Chemical etching or machining are well-known methods of roughening surfaces. Similarly, a low resistance coupling between shoulder  5  and conductor  34  is enhanced by suitably roughening shoulder  5 , shown as shoulder  5 X in FIG.  9 B. 
     In an embodiment, only conductor  32  is provided on PWB  7 . In another embodiment, only conductor  34  is provided on PWB  7 . In another embodiment, both conductor  32  and conductor  34  are provided on PWB  7 . It will be clear to one skilled in the art that, in an embodiment, conductor  32  is one strip of conductor running around the rim of smaller portion  10  of keyhole slot  8 . Alternatively, in another embodiment, conductor  32  is a separate strip of conductor on the top surface of PWB  7  on one side, or each side, at, or near, the rim of smaller portion  10  of keyhole slot  8 . Any conductor on the top surface of PWB  7  on or near the rim of smaller portion  10  of keyhole slot  8  which can be electrically contacted by bottom surface  13  of clamping ring  6  is contemplated. Similarly, conductor  34  can be any conductor on the bottom surface of PWB  7  at or near the rim of smaller portion  10  of keyhole slot  8  which can be electrically contacted by shoulder  5 . 
     In an embodiment, clamping ring  6  is not used, with spring edges  21  bearing directly upon PWB  7 . In this embodiment, tolerances and fastener orientation must be carefully managed to ensure that spring edges  21  bear upon the top surface of PWB  7  when actuated. 
     FIG. 6A shows a cutaway section of a bottom portion of standoff  12  in an embodiment of mounting post  11 . A tapped hole  30  is shown in standoff  12 . Threaded fastener  40 , such as a screw or a bolt, can be used to fasten mounting post  11  to electrical enclosure  35  in a conventional manner, electrically coupling mounting post  11  to the electrical enclosure  35 . Since, in an embodiment, mounting post  11  are electrically coupled to conductor  34 , or to conductor  32 , or to both conductor  34  and conductor  32 , as described above, therefore electrical conductor  34  and/or conductor  32  are be electrically coupled to the chassis  35  as described above. 
     FIG. 6B shows another embodiment used to mechanically and electrically couple mounting post  11  to enclosure  35 . In FIG. 6B, a threaded cylindrical extension  38  of standoff  12  of mounting post  11  is screwed into enclosure  35 . In an embodiment, a portion of standoff  12  is advantageously formed such that a tool can be applied to screw the extension into a threaded hole in the enclosure. For example, as shown in FIGS. 8A and 8B, standoff  12  (shown as standoffs  12 A and  12 B, respectively) could be hexagonal or octagonal, rather than cylindrical, along the axis of standoff  12 , facilitating turning by hand or by a tool. The term “diameter” in such shapes is commonly defined—and is intended here—as the distance between opposing flat sides. FIG. 8A shows a mounting post  11 A featuring hexagonal standoff  12 A. First cylindrical section  17 A is similar to first cylindrical section  17  on previous embodiments. Second cylindrical section  16 A, further containing first hole  18 A are also similar to second cylindrical section  16  and first hole  18  of previous embodiments. FIG. 8B shows a mounting post  11 B featuring octagonal standoff  12 B. First cylindrical section  17 B is similar to first cylindrical section  17  on previous embodiments. Second cylindrical section  16 B, further containing first hole  18 B are also similar to second cylindrical section  16  and first hole  18  of previous embodiments. Any embodiment of standoff  12  that facilitates attachment to enclosure  35  is within the spirit and scope of this invention, including, but not limited to, widening a portion of standoff  12  for grasping, and flattening a portion of standoff  12 . In an embodiment, a lock washer (not shown) is placed between standoff  12  and enclosure  35 . In a further embodiment (not shown), threaded extension  38  extends completely through enclosure  35  and a nut and, optionally, a lock washer is placed on the end of threaded extension  38 . 
     In an embodiment shown in FIG. 6C, threaded extension  39  is formed as a sheet metal screw capable of threading itself into the enclosure, the sheet metal screw being tapered, with the larger diameter end of the sheet metal screw at the end where the sheet metal screw  39  and standoff  12  meet. 
     FIGS. 7A-7D show several ways in which pin  4  can be retained in holes  3  of clamp lever  2  and hole  18  (not visible in these figures) in cylindrical portion  16  of mounting post  11 . 
     FIG. 7A shows pin  4 A inserted in holes  3  and hole  18  (hole  18  not visible in this view). In this embodiment, the diameter of pin  4 A closely matches the diameter of hole  18 , the diameters of holes  3 , or the diameter of hole  18  and the diameters of holes  3 . With a suitably tight fit, friction between pin  4 A and holes  3  and hole  18  keeps pin  4 A inserted. 
     Tightness of fit can be increased through known techniques such as “shrink fitting”. For example, in an embodiment, pin  4 A is cooled, inserted through holes  3  and hole  18 . In this embodiment, cold pin  4 A fits in holes  3  in warmer clamp lever  2 , but with very little difference in diameters between the diameter of pin  4 A and the diameters of holes  3 . In this embodiment, pin  4 A fits freely in hole  18 . As pin  4 A warms relative to clamp lever  2 , pin  4 A becomes tightly held in holes  3 . In an alternative embodiment, cylindrical section  16  of mounting post  11  is heated prior to assembly, thereby enlarging hole  18  relative to cooler pin  4 A. As mounting post  11  is cooled, hole  18  will shrink, providing a tight fit with pin  4 A. These embodiments of shrink fitting are exemplary only, and any combination of heating or cooling pin  4 A, mounting post  11 , and clamp lever  2  is contemplated. 
     FIG. 7B shows an embodiment of pin  4 B, wherein the opposite ends of pin  4 B are made larger following insertion in holes  3  and hole  18 . Impacts, especially impacts when pin  4 B is heated can produce such a bulbous shape on the ends of pin  4 B. If the maximum width of pin  4 B is larger than the diameter of holes  3 , pin  4 B will be retained in position. 
     FIG. 7C shows an embodiment of pin  4 C, wherein the two ends of pin  4 C are crimped after insertion in holes  3  and hole  18 , flattening portions of pin  4 C, but expanding the width in the direction of the crimp. If the maximum width of pin  4 C is larger than the diameter of holes  3 , pin  4 C will be retained in position. 
     FIG. 7D shows an embodiment of pin  4 D, wherein the two ends of pin  4 D are bent after insertion in holes  3  and hole  18 . The bending of pin  4 D as shown is sufficient to retain pin  4 D in position. 
     The above descriptions explained in detail how a clamp lever  2  can be actuated to fasten an object to a mounting post  11  with a spring loaded engagement portion, exemplarily shown comprising a spring element  22 , a cutout  20 , and a spring edge  21 . FIG. 10A shows a further embodiment wherein mounting post  11 Z comprises a standoff  12 Z that has an optional chamfer  14 Z at one or both ends, two first cylindrical sections  17 Z, two second cylindrical sections  16 Z, and two holes  18 Z. This embodiment allows mounting post  11 Z to be fastened to enclosure  35  in the same manner that PWB  7  is fastened to mounting post  11 Z, as shown in FIG. 10B, that is, exactly the same as PWB  7  was fastened to mounting post  11  as described earlier. Fastening two PWBs  7  to mounting post  11  is within the spirit and scope of the invention, as well as clamping one PWB  7  and one enclosure  35 . Furthermore, when two PWBs  7  are fastened to a mounting post, the combined unit can be fastened to enclosure  35  with the invented fastener simply by having one or more keyhole slots in the PWB  7  nearest the enclosure and fastening that PWB  7  to enclosure  35  as described earlier. 
     While the present invention has been described with reference to the details of the embodiments of the invention shown in the drawings, these details are not intended to limit the scope of the invention as claimed in the appended claims.