Abstract:
The present invention relates to a tool, and method of is use, that puts a pair of bevels onto an edge of a printed circuit board (PCB) so that the PCB can be inserted into an expansion slot of a computer. The tool has a bevel wheel, preferably with a bi-laterally symmetrical angle channel shape, that is connected to a carriage. The bevel wheel rolls along the carriage while the bevel wheel is pressed onto the edge of the PCB so as to form the pair of bevels on the edge of the PCB. No material is removed from the PCB while forming the pair of bevels. The bevel wheel is forced upon the edge using a piston that monitors and regulates the pressure applied to the edge of the PCB in order to achieve a preferred height and angular orientation of the pair of bevels.

Description:
BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates to a printed circuit board (PCB) having electronic components thereon, where the PCB is mounted into a connector. More particularly, the present invention relates to the shaping of one edge of a PCB for subsequent insertion of a substrate into a connector. In particular, the present invention relates to a printed circuit board cold-shaping tool that forms a bevel upon an insertion edge of the printed circuit board (PCB), where the bevel on the insertion edge is then inserted into an expansion slot of a computer system, and where the PCB is a memory module or any other kind of plug-in card. 
     2. The Relevant Technology 
     A printed circuit board, sometimes abbreviated PCB, is a thin plate on which chips and other electronic components are placed. Computers consist of one or more boards, often called cards or adapters, each of which has a plurality of electronic components thereon. A PCB is typically inserted into an expansion slot in order to place the electronic components thereon in electrical communication within the computer. The expansion slot is an opening in a computer where a printed circuit board can be inserted to add new capabilities to the computer. Nearly all personal computers, except for portable computers, contain expansion slots for adding more memory, graphics capabilities, and support for special devices. The boards inserted into the expansion slots are called expansion boards, expansion cards, cards, add-ins, and add-ons. 
     The PCB has electrical contacts that are in electrical communication with the electronic devices on the PCB. The PCB preferably has one or more bevels upon one edge in order to facilitate insertion thereof into an expansion slot for a digital computer, or other types of electronic devices. A smooth bevel is preferably formed along the edge of the card without disturbing the electrical contacts on the card. In a typical 72-pin card, the bevel has been conventionally formed by a cutting operation that removes material from the card. These cutting operations have typically been performed by machinery, such as with the Bevel Master® or Bevel Mate® each of which is distributed by Radoll Designs, Inc. located in the city of Thomasville, Ga. USA. 
     FIG. 1 is a cross-sectional elevation view of a prior art bevel device  10  that is used to cut a printed circuit board (PCB)  12  at an insertion edge  14  and at opposing parallel surfaces  30 . PCB  12  is inserted into a slot  16  of a bevel jig  18 . Bevel jig  18  may be supported by a base  20 . As PCB  12  is advanced by forcing it through slot  16 , a pair of knives  24  trim insertion edge  14  to form bevels. Insertion edge  14  is depicted as having a cross-sectional thickness that fits into and is slightly smaller than slot  16 . During the trimming of insertion edge  14 , a portion of PCB  12 , called a trimming  26 , falls away from PCB  12  and must be removed. 
     One of the problems that occurs in the prior art is that the presence of trimming  26  causes refuse and refuse management. Where a plurality of pins  28  are disposed along insertion edge  14  and have valuable metal such as gold that is cut away from PCB  12  as part of trimming  26 , additional work must be carried out to recover and reuse the valuable metal in trimming  26 . 
     Another problem that exists in the prior art is the fact that knives  24  are subject to losing a sharp edge and becoming dull due to on going use. As knives  24  begin to dull, successive PCBs will be beveled differently due to progressively varying degrees of sharpness of the cutting edge of knives  24 . In other words, where printed circuit board  12  is the first to be trimmed by a brand new set of knives  24 , a “clean” cut may be performed, but the next printed circuit board will experience knives that are just slightly duller. Consequently, as the useful life of knives  24  nears their end, significantly different bevels on a PCB can be formed than when knives  24  are sharp. 
     Another problem occurs when one knife  24  may be sharper than another knife  24 . An unevenness in sharpness during the beveling operation will cause a greater degree of friction on the duller knife  24 . A difference or excessive friction on a knife  24  can cause PCB  12  to fragment instead of cleanly slicing insertion edge  14  of PCB  12 . Also, the increased pressure against the duller blade of knife  24  will cause PCB  12  to bow or warp. Bowing or warping will in turn cause a greater volume of trimming  26  to be removed from either of surfaces  30  and/or insertion edge  30 . Alternatively, if both occurrences of knives  24  are dull, the entire printed circuit board may be destroyed due to both uneven cutting, excessive friction, fragmentation, warping, or bowing. Still further, too large or too small of a volume of trimming  26  may be removed from one of opposite surfaces  30  of PCB  12 . Consequently, an uneven formation of bevels may cause PCB  12  to be inserted into an expansion slot without proper registration in the slot. This improper registration can cause electrical communication between the expansion slot and the electric contacts on PCB  12  to be established on only one side of PCB  12 . 
     Another problem that occurs due to the cutting nature of the prior art is, where the material of the pins  28  is scraped instead of cut by knives  24 , the scraping causes the material of pins  28  to pull away from the surface  30 . Where the material of pins  28  is harder than the material of PCB  12 , or where the material of pins  28  is not efficiently bonded to the surface  30  of PCB  12 , the material of pins  28  will be scraped away after a manner that causes it to delaminate from surface  30  of PCB  12 . Consequently, the effect will be inadequate electrical contact when PCB  12  is inserted into an expansion slot. 
     Along the length of insertion edge  14  (the length is pictured as being perpendicular to the plane of the Figure), PCB  12  may have a varying cross-sectional thickness as PCB  12  is presented against knives  24 . The varying cross-sectional thickness may also cause the cutting operation to be nonuniform. Where the cross-sectional thickness is too thin, cutting may not occur. Where the cross-sectional thickness is too wide, cutting may become irregular or improbable because PCB  12  may be forced out of slot  16 . 
     What is needed in the art is a tool, and a method of using the same, that forms beveled edges in a printed circuit board while overcoming the problems of the prior art. Such a tool, and a method of its use, is disclosed and claimed herein. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a printed circuit board (PCB) edge shaping tool, and method of its use. The inventive tool and its method of use overcomes the problems of the prior art associated with cutting and grinding to shape a PCB. The PCB has an insertion edge that extends between opposing parallel surfaces of the PCB. The PCB also has a bottom edge that is opposite of and parallel to the insertion edge. The inventive tool is used to form a bevel on the PCB without removing material from the PCB. The bevel formed by the inventive method of using the inventive tool extends between the insertion edge and each of the opposing parallel surfaces of the PCB. 
     The inventive tool includes a support surface for supporting the bottom edge of the PCB, and also includes a device for moving a shaping tool to form a bevel on the PCB without removing material from the PCB. The bevel is formed while the support surface supports the bottom edge of the PCB and while the shaping tool makes contact with both the insertion edge of the PCB and the opposing parallel surfaces of the PCB. 
     The printed circuit board can be a memory module or for any other kind of plug-in card such as a modem card, a video card, or an audio card. The inventive method using compressive forces to form bevels upon an edge of a printed circuit board without removing material from the printed circuit board (PCB). Prior to the beveling operation of the present invention, the edge of the PCB has a first shape that preferably is rectangular is cross section. The first shape is transformed into a second shape, which is preferably beveled, by the inventive method. Once the bevels are formed, the bevels aide in the insertion and registration of the printed circuit board into an expansion slot of a computer chassis. 
     In one embodiment of the present invention, a rolling cold-shaping tool rolls along an edge of a printed circuit board in order to form preferred bevel shapes. The rolling coldshaping tool can be a single bevel wheel or a collection of in-parallel bevel wheels that may perform the cold-shaping function upon an array of printed circuit boards that may be set in a tray or other collective container. The shape of the edge of a PCB is transformed into the beveled shaped by the shaped, bevel wheel. The bevel wheel has a bilaterally symmetrical angled channel shape into which the edge of the PCB is inserted. Compressive stresses directed at the edge of the PCB accomplish the formation of the bevel shape without removing material from the PCB. 
     The present invention also relates to a cold roll bevel system. The cold roll bevel system comprises a PCB insert assembly that comprises two parallel, opposed, spaced apart, slotted structures disposed against a plate. The plate may be varied in length to accommodate different length PCBs. An edge of the PCB is inserted into the PCB insert assembly and is then compressed in a compressive tool such as a shaped wheel, a channel, or an articulating press. The compression forms one or more bevels in the edge of the PCB without removing material from the PCB. Where the compressive tool is a wheel, the wheel is driven along the edge of the PCB into which the one or more bevels are to formed. The present invention may be carried out by having an operator or a machine place a memory module or another PCB-mounted card into the PCB insert assembly. Where the length of the PCB may vary, the plate of the PCB insert assembly may be varied. 
     Under certain conditions, a plurality of memory modules may be processed to form bevels on an edge of the respective PCB according to the present invention. In particular, a plurality of parallel occurrences of a bevel wheel may be mounted upon a bevel wheel carriage and a corresponding plurality of memory module inserts may be disposed beneath the bevel wheel carriage. Under these circumstances, each occurrence of a bevel wheel may have a separate sensor in order to apply a preferred even pressure force upon each occurrence of the bevel edge. 
     In another embodiment of the present invention, formation of the bevel may be carried out by inserting the insertion edge of the PCB into a shaped channel. The insertion edge is then forcibly moved through the channel such that the insertion edge assumes the shape of the shaped channel without removing material from the PCB. As such, the insertion edge of the PCB will have a preferred bevel height and bevel angle. The shape of the channel in the present embodiment may be substantially the same, when viewed in cross section, as the shape of the bilaterally symmetrical channel of the shaped wheel of the previous embodiment. 
     In yet another embodiment of the present invention, the bevel may be formed by compression forces brought to bear upon the insertion edge of a PCB using the articulation of a press. The pressure upon the insertion edge forms bevels having both a bevel height and a bevel angle without removing material from the PCB. The cross-sectional view of such an articulating press in the present embodiment would be substantially the same when in a closed position of such a press as that of the bilaterally symmetrical channel of the shaped wheel of the previously described embodiment. 
     These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the manner in which the above-recited and other advantages of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 is an elevational cross-sectional view of a prior art beveling device that forms beveled edges by cutting material away from a printed circuit board; 
     FIG. 2 is a perspective view of a memory module that may be beveled in the inventive printed board edge shaping tool; 
     FIG. 3 is an elevational cross-section view taken along the section line  3 — 3  from FIG. 2; 
     FIG. 4 is an elevational cross-section view illustrating the bevel formed on the bevel edge of the printed circuit board depicted in FIG. 3; 
     FIG. 5 is an elevational cross-section view illustrating the formation of a bevel within a bevel wheel according to the invention; 
     FIG. 6 is a perspective view of a cold roll bevel system according to the present invention; 
     FIG. 7 is a perspective view of the inventive cold roll bevel system showing the bevel wheel carriage and the carriage track; 
     FIG. 8 is an alternative perspective view of the inventive cold roll bevel system showing the memory module affixed in a printed circuit board insert upon a plate; 
     FIG. 9 is a perspective view of an embodiment of the inventive cold roll bevel system where the bevel wheel carriage has placed the bevel wheel onto the bevel edge of the memory module; 
     FIGS. 10 and 11 are elevational side views that demonstrates placement of the bevel wheel upon the bevel edge of the memory module in the inventive cold roll bevel system; 
     FIGS. 12 and 13 demonstrate the movement of the bevel wheel across the bevel edge of the memory module by the motion of the bevel wheel carriage in the inventive cold roll bevel system; and 
     FIG. 14 is a plan view of a memory module inserted into a memory module insert that rests upon a plate. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made to figures wherein like structures will be provided with like reference designations. It is to be understood that the drawings are diagrammatic and schematic representations of embodiments of the present invention and are not limiting of the present invention nor are they necessarily drawn to scale. 
     FIG. 2 is an elevational perspective view of a package that may be a modem card, a graphics card, a memory card, or another plug-in card. In FIG. 2, the card is seen at reference numeral  32  as a memory module  32 . Memory module  32  is shaped by use of the inventive printed circuit board edge shaping tool. Memory module  32  includes an insertion edge  14  that is inserted into an expansion slot of a computer chassis after it is beveled. Memory module  32  also includes a bottom edge  38  located opposite and parallel to insertion edge  14 . A pin array  34  is disposed along insertion edge  14 . Other edges of memory module  32  are a bottom edge  38  that is opposite and parallel to insertion edge  14 , and a leading edge  40  that is opposite and parallel to a trailing edge  42 . Memory module  32  may include a printed circuit board (PCB)  12  and at least one device  36 , such as a microelectronic chip. 
     FIG. 3 is an elevational cross-section view taken along the section line  3 — 3  from FIG. 2 that illustrates memory module  32  with pin array  34  prior to the formation of a bevel. FIG. 3 illustrates PCB  12  having pins  28  disposed upon the surface  30  of PCB  12 . The formation of a bevel is to be carried out at insertion edge  14 . FIG. 4 is an elevational cross-section view illustrating an example of a bevel  44  that is formed from surfaces  30  and insertion edge  14  of PCB  12  using the inventive method. The right angle between insertion edge  14  and surface  30  in FIG. 3 is converted into bevel  44  seen in FIG.  4 . 
     FIG. 4 illustrates that bevel  44  is made in this embodiment after a fashion that does that affect the structure of pins  28  disposed upon surface  30  of PCB  12 . It is understood, however, that bevel  44  may be of sufficient size so as to include a portion of pins  28  upon the surface of bevel  44 . Bevel  44  may have a bevel height  62  in a range from about 20 thousandths of an inch to about 1 thousandths of an inch. Preferably, bevel height  62  is in a range from about 2 thousandths of an inch to about 10 thousandths of an inch. Bevel  44  may also have a bevel angle  64  in a range from about 15° to about 60°, preferably in a range from about 20° to about 45°, and most preferably about 30°. 
     FIG. 5 is an elevational cross-section view of PCB  12  during the formation of bevel  44 . A bevel wheel  56  is illustrated as being a shaped wheel having a bilaterally symmetrical angled channel  78  into which PCB  12  is inserted at insertion edge  14 . Compressive stresses directed at insertion edge  14  at the juncture of insertion edge  14  and surface  30  accomplish the formation of bevel  44 . An angle  80  is illustrated as being 90° minus bevel angle  64 . 
     FIG. 6 is a perspective view of a cold roll bevel system  46  according to the present invention. FIG. 6 illustrates the placement of memory module  32  into a memory module insert  48 . 
     FIG. 7 is a perspective view of an embodiment of the inventive cold roll bevel system  46  with a cover removed in order to better reveal memory module insert  48  and to reveal a bevel wheel carriage  50  that moves along a carriage track  52 . FIG. 7 illustrates the placement of memory module  32  into memory module insert  48  and further illustrates that memory module insert  48  can be moved in an X-direction toward a front  66  of cold roll bevel system  46  where an operator may be stationed. After the placement of memory module  32  into memory module insert  48 , memory module insert  48  is retracted away from front  66  of cold roll bevel system  46  to be aligned under bevel wheel carriage  50  in order to bevel insertion edge  14  of PCB  12  of memory module  32 . FIG. 8 illustrates memory module  32  affixed in memory module insert  48 . Memory module insert  48  comprises two parallel, opposed, spaced apart structures that are disposed against a plate  54  to hold plate  54  in a fixed position while an edge of the PCB is being shaped. These two parallel, opposed, spaced apart structures allows PCB  12  of memory module  32  to provide sufficient resistance to allow a bevel to be formed upon insertion edge  14 . Memory module insert  48  including plate  54  have been retracted beneath bevel wheel carriage  50  in order to align a bevel wheel  56  with insertion edge  14 . 
     FIG. 9 shows that bevel wheel carriage  50  is adjusted in the Y and Z directions to place bevel wheel  56  directly upon insertion edge  14 . In this configuration, bevel wheel carriage  50  is prepared to roll bevel wheel  56 , in this embodiment from left to right with respect to FIG. 9 along insertion edge  14  in order to form dual beveled surfaces terminating at insertion edge  14 . 
     FIGS. 10 and 11 illustrate elevational side views that demonstrate the placement of bevel wheel  56  upon PCB  12 . In FIG. 10, bevel wheel carriage  50  is illustrated as being retracted upwardly away from PCB  12  in memory module insert  48 . In FIG. 11, bevel wheel carriage  50  has been pressed downwardly with respect to FIG. 12 by use of a piston  68  in order to position bevel wheel  56  upon PCB  12  of memory module  32  as it is affixed in memory module insert  48 . Piston  68  or an equivalent displacement device, such as a shaft that is advanced by a rack and pinion gear, is actuated to place bevel wheel  56  onto insertion edge  14  of memory module  32 . 
     The force that piston  68  applies upon insertion edge  14  of memory module  32  may be selected in order to achieve a preferred degree of faceting in the formation of the dual bevels. The pressure is preferably applied at a constant amount based upon the desired bevel shape. The height and the thickness of the printed circuit board will also influence the pressure. Preferably, the amount of pressure that is placed by bevel wheel  56  onto any given portion of memory module  32  along insertion edge  14  is in a range from about 15 psi to about 25 psi, preferably from about 18 psi to about 22 psi, and most preferably about 20 psi. 
     FIGS. 12 and 13 are elevational front views of the detail of the inventive cold roll bevel system  46 , and further illustrate plate  54  and a pair of memory module inserts  48  that function to hold memory module  32 . Bevel wheel  56  is illustrated as having made contact with memory module  32  upon insertion edge  14  near or at leading edge  40  of memory module  32 . Under the preferred pressure of bevel wheel  56  applied upon insertion edge  14  at or near leading edge  40 , bevel wheel carriage  50  is advanced from left to right with respect to FIG. 12 from leading edge  40  toward trailing edge  42 . Bevel wheel carriage  50  advances along carriage track  52  under a preferred pressure in order to achieve a preferred bevel  44  (not pictured). FIG. 13 demonstrates the completion of motion of bevel wheel carriage  50  from left to right that causes bevel wheel  56  to roll along insertion edge  14  of memory module  32 , beginning at leading edge  40  and ending at trailing edge  42 . After the completion of the formation of bevel  44  (not pictured), piston  68  is retracted, thus retracting also bevel wheel carriage  50  and bevel wheel  56  away from insertion edge  14  of memory  11  module  32 . 
     FIG. 14 is a top plan view of memory module insert  48  and plate  54  holding memory module  32  within a leading notch  70  that holds leading edge  40  and a trailing notch  74  that holds trailing edge  42 . As depicted in FIG. 14, each of leading notch  70  and trailing notch  74  has a width  76  and PCB  12  has a thickness  83 . A clearance, which is defined as the difference between width  76  and thickness  82 , is necessary so that PCB  12  that fits within either of leading notch  70  or trailing notch  72 . The amount of clearance is preferably in a range from about 1 mil to about 20 mils, preferably from about 2 mils to about 16 mils, and more preferably about 10 mils. 
     The present invention is carried out by compressing insertion edge  14  at the juncture between insertion edge  14  and surface  30  as depicted in FIG. 3 by the method depicted in FIG. 5, to form bevels  44  as depicted in FIG.  4 . The present invention may be carried out by having an operator manually place memory module  32  into memory module insert  48 , or by placing memory module  32  using automated machinery. Length  72  may vary with the length of printed circuit boards  12 . As such, memory module insert  48  may be connected to different sizes of plate  54  in order to accommodate different lengths of PCB  1212 . An example of an industry standard PCB is a 72-pin printed circuit board. Where other lengths of PCB  12  may be larger or smaller, plate  54  may be changed to accommodate the length of a given PCB  12 . 
     In the inventive method, an operator may bring a tray (not pictured) of memory modules  32 , that may have as many as fifty memory modules or more per tray. The operator, or automated machinery, removes one memory module  32  from the tray and places it into memory module insert  48 . A sensor may be placed at or near memory module insert  48  to confirm that memory module  32  has been inserted into notches  70 ,  74 . Cold roll bevel system  46  then may move memory module insert  48  in the Y-direction to a position beneath bevel wheel carriage  50  in order to align bevel wheel  56  with insertion edge  14 . Piston  68  then advances bevel wheel carriage  50  in order to allow bevel wheel  56  to contact insertion edge  14  as depicted in FIGS. 9,  10  and  11 . Once bevel wheel  56  is placed at leading edge  40 , bevel wheel carriage  50  is moved in the X-direction along insertion edge  14  toward trailing edge  42  as depicted in FIGS. 12 and 13. Following the formation of bevel  44 , bevel wheel carriage  50  is retracted by the withdrawal of piston  68 , memory module insert  48  is returned to its extended position, and memory module  32  may be removed from memory module insert  48 . 
     Under certain conditions, a plurality of memory modules may be processed to form bevels on the insertion edge of the respective PCBs according to the present invention. In this embodiment, a plurality of parallel occurrences of bevel wheel  56  are mounted upon bevel wheel carriage  50  and a corresponding plurality of memory module inserts  48  are disposed beneath bevel wheel carriage  50 . Each occurrence of bevel wheel  56  may have a separate sensor in order to apply a preferred even pressure force upon each occurrence of insertion edge  14 . 
     In another embodiment of the present invention, the formation of bevel  44  may be carried out by inserting insertion edge  14  into a channel. When insertion edge  14  is forced through the channel, both surfaces  30  and insertion edge  14  will have a pair of bevels formed thereat. The shape of the bevels will have the same bevel height  62  and bevel angle  64  as depicted in FIG.  4 . The shape of the channel may be substantially the same, when viewed in cross section, as the shape of bilaterally symmetrical channel  78  seen in FIG.  5 . In this embodiment of using a channel instead of bevel wheel  56 , the length of PCB  12  between opposing edges  40  and  42  must be taken into consideration in order to apply a pressure uniformly along insertion edge  14 . As stated above, the preferred pressure is in a range from about 15 psi to about 25 psi, preferably from about 18 psi to about 22 psi, and most preferably about 20 psi. Accordingly, where the length of PCB  12  is shorter than a typical 72-pin memory module  32 , the gross pressure applied by piston  68  will be less than where a full 72-pin memory module is being beveled. 
     In other embodiments of the present invention, bevel  44  may be formed by compressive forces that are brought bear by the articulation of a press. The press is thus used to form both bevel height  62  and bevel angle  64  as depicted in FIG. 4 according to a particular application. Such an articulating press, when in a closed position thereof, would be substantially the same as seen in FIG. 5, where the dashed line  82  represents the closed interface formed by two closed press platens of the press. Similarly to the foregoing channel embodiment, alterations of the articulating press pressure onto insertion edge  14  can be adjusted to achieve a desired result by application of a compressive force in the preferred pressure range stated above. 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrated and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.