Abstract:
A tool is provided herein for separating stacked strips of semiconductor structures held by a magazine, which strips have become attached together. The tool is made up of first and second elongated members in side-by-side relation, each member defining a plurality of teeth along an edge thereof. The first and second members are mounted together so as to allow relative reciprocal movement therebetween, so that relative reciprocal movement between the pluralities of teeth is provided. The tool is held with the teeth against the edges of strips carried by the magazine, and the operator squeezes and releases member handles to provide relative reciprocal movement of the teeth. This back-and-forth reciprocal movement causes the teeth to rub against and force apart the strips, to in turn separate them.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to semiconductor fabrication, and more particularly, to a tool for use in the fabrication of semiconductor devices. 
     2. Discussion of the Related Art 
     End-of line (EOL) fabrication of semiconductor devices includes processing at mold, post mold cure, plating, and trim and form stations. A magazine holding a stack of strips including lead frames with die thereon is loaded onto the mold station. The strips are fed one at a time from the magazine into the mold station for processing, and are loaded one at a time from the station into another magazine after such processing. The loaded magazine is then moved to and placed in a cure oven at the post mold cure station. After curing, the magazine containing the strips is loaded onto the next (plating) station. The strips are fed one at a time from the magazine into the plating station for processing, and are loaded one at a time from the station into another magazine after such processing. This loaded magazine is transported to a trim and form station, where again the strips are fed one at a time from the magazine into the trim and form station for processing. 
     A typical magazine  20  for use in this environment is shown in FIG.  1 . The magazine  20  includes a back portion  22 , side portions  24 ,  26 , front edges  28 ,  30  and a bottom support plate  32  on which a plurality of strips  34  is stacked. The magazine  20  as shown in FIG. 1 contains, for example, a stack of strips  34  (FIG. 2) each of which is made up of a lead frame  36  and a plurality of die (not shown) packaged in molding compound  38 . As noted, the bottom portions of packages  38  of a strip  34  lie on and contact the top portions of the packages  38  of the strip  34  therebelow. 
     After, for example, post mold cure, which is undertaken at a very high temperature for an extended time, it will be readily understood that with the strips  34  stacked as shown in FIGS. 1 and 2, the packages  38 , and thus the strips  34 , may become attached to or stuck to each other. In this state, when the magazine  20  holding these strips  34  is installed at the next (plating) processing station, the mechanism for feeding strips  34  into that processing station may pick up two or more (stuck together) strips  34  at the same time, causing jamming of the processing station and undesirable process down time. 
     In attempting to deal with this problem, prior to installation of the magazine  20  at a processing station, an attempt can be made to separate the stuck-together strips  34  manually, i.e., using one&#39;s fingers. This is time-consuming and has proven to be ineffective, as some strips  34  may remain attached or stuck together. As an alternative, tweezers or other sharp objects have been used in an attempt to separate the strips  34 , but it has been found that this method has great potential for causing strip damage. 
     Therefore, what is needed is a method/tool for separating strips that may have become attached together, to insure that a magazine loaded onto a processing station contains only separated or free strips which can be fed one at a time from the magazine into the processing station. 
     SUMMARY OF THE INVENTION 
     The present invention is a tool for separating stacked strips of semiconductor structures. The tool includes first and second elongated members in side-by-side relation. Each member defines a plurality of teeth along an edge thereof, the first and second members being positioned so that the teeth of the first elongated member are adjacent and lie along the teeth of the second elongated member. The first and second members are mounted together to allow relative reciprocal movement therebetween, so that relative reciprocal movement between the first and second pluralities of teeth is provided. The tool is held with the teeth thereof against strips carried by a magazine, and the operator squeezes and releases member handles to provide relative reciprocal movement of the teeth. This back-and-forth, reciprocal movement causes the teeth to rub against and force apart the edges of the strips, to in turn separate them. 
     The present invention is better understood upon consideration of the detailed description below, in conjunction with the accompanying drawings. As will become readily apparent to those skilled in the art from the following description, there is shown and described an embodiment of this invention simply by way of the illustration of the best mode to carry out the invention. As will be realized, the invention is capable of other embodiments and its several details are capable of modifications and various obvious aspects, all without departing from the scope of the invention. Accordingly, the drawings and detailed description will be regarded as illustrative in nature and not as restrictive. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as said preferred mode of use, and further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a magazine holding a plurality of strips, as is well-known in the prior art; 
     FIG. 2 is a sectional view of the stacked strips of FIG. 1; 
     FIG. 3 is a side view of the first elongated member of the tool of the present invention; 
     FIG. 4 is a side view of the second elongated member of the tool of the present invention; 
     FIG. 5 is a side view of the tool of the present invention, including the first and second elongated members thereof; 
     FIG. 6 is a sectional view taken along the line  6 — 6  the FIG. 5; 
     FIG. 7 is a perspective view similar to that shown in FIG. 1, and showing the use of the tool; 
     FIG. 8 is enlarged view of a portion of the device of FIG. 7, showing the tool in a first state; and 
     FIG. 9 is a view similar to that shown in FIG. 8, but with the tool in a second state. 
    
    
     DETAILED DESCRIPTION 
     Reference is now made in detail to specific embodiment of the present invention that illustrates the best mode presently contemplated by the inventor for practicing the invention. 
     FIGS. 3 and 4 show the main elements making up the tool  40  of FIG.  5 . FIG. 3 shows a first elongated member  42  that is generally flat and rectangular in configuration, and defines along an elongated edge thereof a plurality of teeth  44 . Each of the teeth  44  has a first side  46  that is substantially perpendicular to the longitudinal axis  48  of the member  42 , and a second side  50  angled toward the first side  46 , at an angle “a” of substantially 45° from the longitudinal axis  48  of the member  42 , the first and second sides  46 ,  50  terminating in a rounded tooth point  52 . The points  52  of the teeth  44  lie in a straight line. A handle  56  extends from an edge of member  42  opposite the row of teeth  44 . 
     A second elongated member  60  is shown in FIG.  4 . This elongated member  60  is also generally flat and rectangular in configuration, and defines along an elongated edge thereof a plurality of teeth  62 , configured similar to the teeth  44  of the first elongated member  42 . That is, each of the teeth  62  has a first side  64  that is substantially perpendicular to the longitudinal axis  66  of the member  60 , and a second side  68  angled toward the first side  64  at an angle “b” of substantially 45° from the longitudinal axis  66  of the member  60 , the first and second sides  64 ,  66  terminating in a rounded point  70 . The elongated member  60  also includes a handle  72  extending from an edge thereof opposite the row of teeth  62 , similar to that of the elongated member  42 . The points of the teeth  70  also lie in a straight line. 
     The elongated members  42 ,  60  are positioned in side-by-side relation, member  42  lying on top of member  60  as shown in FIG. 5, with their longitudinal axes  48 ,  66  substantially parallel. The elongated member  60  includes slots  76  that lie parallel to the longitudinal axis  66  of the member  60 , and pins  78  extend through these slots  76  in sliding relation therewith, and are secured by welding in apertures  80  in member  42  (FIG.  6 ). The pins  78  have heads  82  thereon so that the assembly is held together, but with sufficient clearance being provided between elements to allow a sliding fit between the member  42  and member  60 , along the longitudinal axes  48 ,  66  of the members  42 ,  60 , as allowed and limited by the slots  76  and pins  78 . The first and second pluralities of teeth  44 ,  62  lie adjacent and along each other in side-by-side relationship, and extend in the same direction, with the angled sides  50 ,  68  of the respective pluralities of teeth  44 ,  62  being substantially parallel. A spring  84  interconnects the first and second members  42 ,  60  and resiliently biases the members  42 ,  60  into first relative positions (handles  56 ,  72  further apart, FIG.  5 ), limited and determined by the slots  76  and pins  78  as shown in FIG.  5 . However, through application of pressure by the fingers of the user of the tool  40  on the handles  56 ,  72  in the directions indicated by the arrows (FIG.  5 ), the first and second members  42 ,  60  can be moved to second relative positions (handles  56 ,  72  closer together) against the resilience of spring  84 , again limited and determined by the slots  76  and pins  78 . 
     FIG. 7 shows the tool  40  being used with a magazine  20  holding stacked strips  34  that, for example, have just the left the cure station, and a number of them may be stuck together as described above. As shown in FIG. 8, the teeth  44 ,  62  of the tool  40 , positioned as shown in FIG.  8  and FIG. 5 under the force of spring  84  and limited in movement by the pins  78  and slots  76 , are brought into engagement with the edges  36 A of the lead frames  36  of the strips  34  (FIG.  8 ), and the handles  56 ,  72  of the members are moved together by application of finger pressure to move the teeth  44 ,  62  over the edges  36 A and bring the teeth  44 ,  62  into the relative positions (limited by the pins  78  and slots  76 ) shown in FIG.  9 . This initial movement of the members  42 ,  60  will cause some of the attached strips  34  to separate due to the friction applied by the moving teeth  44 ,  62  to the strips  34 , and also due to the separation of teeth  44 ,  62  relative to each other as this movement occurs. With the members  42 ,  60  (and their teeth  44 ,  62 ) in their second relative positions (handles  56 ,  72  closer together), the points  52 ,  70  of adjacent teeth  44 ,  62  of the two sets of teeth are quite close together and overlap to a large extent (FIG.  9 ), allowing the points  52 ,  70  of the teeth  44 ,  62  to readily extend between edges  36 A of adjacent pairs of strips  34 , so that movement of the first and second members  42 ,  60  back to their original positions (handles  56 ,  72  further apart), under the resilience of the spring  84  and also through the force of the fingers of the user, applies separating force to each adjacent pair of strips  34 . A back and forth relative movement of the members  42 ,  60 , along with repositioning of the tool  40  itself relative to the strips  34  as chosen (up or down in FIG.  5 ), can be repeated several times in a period of a few seconds to insure that all strips  34  are properly separated. The magazine  20  then can be moved to the next station, and it is insured that each strip  34 , in a free or unstuck state, can be mechanically removed one at a time without problem to avoid jarring at that station. 
     The particular configuration of the teeth  44 ,  62 , and the relationship of one set of teeth to the other, is an important feature. It will be seen that with sides  46  of the teeth  44  perpendicular to the longitudinal axis  48  of the member  42 , and with sides  50  of the teeth at an angle of 45° with respect to the longitudinal axis  48  of the member  42 , and also with the sides  64  of the teeth  62  perpendicular to the longitudinal axis  66  of the member  60 , and with the sides  68  of the teeth  62  at an angle of 45° with respect to the longitudinal axis  66  of the member  60 , and further with the angled sides  50 ,  68  parallel to each other, an edge  36 A of a strip lead frame  36  cannot be caught (and possibly damaged) between teeth, but as teeth come together, will be forced out from between adjacent teeth. Thus, the lead frames  36  cannot be damaged by the tool  40 , yet the tool  40  still provides effective separating force of the stacked strips  34 . 
     It will therefore be seen that a tool has been provided for separating attached, stacked strips in a magazine, so that the strips may be in readily fed into a processing station one-by-one as required to avoid jamming of the processing station. The tool is highly effective and rapid in separating attached strips, meanwhile avoiding damage to the strips. 
     The foregoing description of the embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Other modifications or variations are possible in light of the above teachings. The embodiment was chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill of the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.