Abstract:
An independent leadframe transport system for use with an integrated-circuit processing has a main drive unit having at least one tool-drive. A stack unit is moveably coupled to the main drive unit for storing unprocessed and processed leadframes. A leadframe transport carousel is coupled to the stack unit which loads an unprocessed leadframe from the stack unit and returns a processed leadframe back to the stack unit.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is in the field of leadframe transport systems and methods therefore, and more particularly, is an independent. leadframe transport system which is separable and independent from the tool(s), in which each leadframe is individually held by a to leadframe handler assembly thereby eliminating the stresses normally imparted to the leadframe, and a method therefor. 
     2. Description of the Related Art 
     Historically the transportation of leadframes through tool(s), used to cut, bend, mark, separate, etc., has been performed by directly manipulating and physically moving a leadframe from position to position, or from tool to tool. This direct handling of the leadframe imparts a great deal of working stress to the leadframe. In past times of large geometry integrated circuits and their correspondingly rigid leadframes, these stresses could be tolerated by the leadframe and its associated integrated circuit. However, today&#39;s technology has developed much smaller and much more dense integrated circuits. Therefore, the leadframes have also had to become correspondingly smaller, and thus are much more fragile than their predecessors. These smaller geometry, more fragile, leadframes are very susceptible to physical damage as the leadframes are directly handled by the leadframe transport system (“leadframe transport” hereinafter) and stack equipment, particularly during high speed operations, or during physical handling by human operators. Additional problems arise when the leadframe transport and tool(s) are a compact integrated unit, and when damage of a leadframe occurs, such as the bending or tearing of the leadframe. Such a deformed leadframe often results in jamming of the leadframe transport and tool(s). This jamming requires the services of an experienced technician to disassemble the leadframe transport and tool(s), remove the damaged leadframe, repair the leadframe transport and tool(s), and assemble the leadframe transport and tool(s) again. During the period of time needed to solve the jammed leadframe problem the entire integrated-circuit processing equipment (“equipment” hereinafter) is non-functional, resulting in expensive production losses due to idle equipment and lost production capacity. 
     A further problem due to the fragility of today&#39;s modern leadframes, is that at times it may be necessary for an operator to physically remove a leadframe from the leadframe transport for inspection. This inspection involves the direct physical handling of the leadframe by the operator. The operator must remove the leadframe from the leadframe transport by hand, conduct the inspection, and then return the leadframe to the leadframe transport. The physical handling of a leadframe by an operator easily results in very large stresses being imparted to this fragile leadframe. Additionally, alignment problems may occur between the leadframe and the tool when the operator attempts to re-insert the leadframe back into the leadframe transport. 
     Therefore a need existed for a leadframe transport and method to handle these new fragile leadframes to avoid irreparable and expensive damage to leadframes and the associated integrated circuit. Additionally, a need existed for a leadframe transport and method to handle these new fragile leadframes so as to prevent jamming and subsequent damage to the leadframe transport and tool(s). Yet another need existed for a leadframe transport and a method to allow the easy removal of damaged leadframes from the leadframe transport without requiring the complete disassembly of the leadframe transport and tool(s). 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a leadframe transport and method which can, beside the rigid leadframes, handle fragile leadframes and avoid irreparable and expensive damage to leadframes and the associated integrated circuit. 
     Another object of the present invention is to provide a leadframe transport and method to transport fragile leadframes so as to prevent jamming and subsequent damage to the leadframe transport and tool(s). 
     Yet a further object of the present invention is to provide a leadframe transport and a method to allow the easy removal of damaged leadframes from the leadframe transport and tool(s) without requiring the disassembly of the leadframe transport and tool(s). 
     BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In accordance with one embodiment of the present invention an independent leadframe transport for use in equipment is disclosed. The independent leadframe transport is for use in equipment which comprises; a main drive unit having at least one tool-drive, a stack unit coupled to the main drive unit, and a leadframe transport carousel coupled to the stack unit and positioned proximate to the at least one tool-drive. The stack unit is translationally coupled to the main drive unit so that the leadframe transport carousel may be selectively positioned within the at least one tool-drive in an in-tool position and without the at least one tool-drive in an out-tool position. 
     In accordance with yet another embodiment of the present invention, a method of processing leadframes allowing the removal of the leadframe transport from the tool area of the equipment is disclosed. The method of processing leadframes allowing the removal of a leadframe transport from the tool area of the equipment comprises the steps of; providing a leadframe transport carousel adapted and configured to be coupled to a stack unit, adapting and configuring the stack unit to be translationally hinged whereby the leadframe transport carousel is selectively translated between an in-tool position within the tool area and an out-tool position without the tool area. 
     The foregoing and other objects, features, and advantages of the invention will be apparent from the following, more particular, description of the preferred embodiments of the invention, as illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a perspective top view of the leadframe transport carousel, magazines and buffers of the independent leadframe transport of the present invention. 
     FIG. 2 is a perspective side view of the independent leadframe transport of the present invention shown in the “in-tool” position. 
     FIG. 3 is a perspective side view of the independent leadframe transport of the present invention shown in the “out-tool” position. 
     FIGS. 4-8 are top views of the leadframe transport carousel showing the relative positions of the leadframe transport carousel components during the indexed process pitch sequence. 
     FIGS. 4 a - 8   a  are corresponding side looking views of the leadframe transport carousel showing the relative positions of the pitch strips and the leadframe handler assemblies during the indexed process pitch sequence. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Due to the more fragile modern leadframes, a new method, and apparatus for handling the leadframes is presented. The new independent leadframe transport and method involves the concept that each leadframe is only gripped, or held, one time from the initial removal of a leadframe from an on-load buffer, its transport through the process area including its tool(s) and their processing, back through the return area, and to the release of the processed leadframe at the off-load buffer. This single-step handling of a leadframe avoids the physically stressful results of multiple handling events of the leadframes at the many steps from on-load to off-load that existed in the prior art. This single-step handling concept is an important feature in the use of a leadframe handler assembly. The leadframe handler assembly is key to the improved handling of leadframes because this allows handling a leadframe only one time from its initial placement into the leadframe handler assembly, and then through the remainder of the processing of the leadframe. Through this whole process, the actual operator physical and machine mechanical handling is restricted to the leadframe handler assembly, which is itself holding the leadframe. To further facilitate this concept of a method and apparatus for handling leadframes, each leadframe handler assembly is transported by a leadframe transport carousel. The leadframe carousel moves a plurality of leadframe handler assemblies through the tool(s). Yet another important feature of the present invention is the ability to translate the leadframe transport carousel out of the tool area. As discussed previously, if jamming occurs within the tool area of prior art equipment a technician must disassemble the leadframe transport and tool(s) to remove the jammed leadframe. The disassembly process is inherently stressful and damaging to the leadframes that are not jammed within the tool area Therefore, to ensure and aid in minimizing the stresses that might be imparted to a leadframe in the event of a leadframe jam, the stack assembly is designed to remove the leadframe transport carousel and its associated leadframe handlers, out of the tool area. Additionally, the feature of removing the entire leadframe transport carousel out of the tool area in the event of a jam, not only allows the easy removal of damaged leadframes from the tool area without requiring the disassembly of leadframe transport and tool(s), but also increases the accessibility to the interior of the leadframe transport and tool(s). Also, the removal of the leadframe transport carousel and the subsequent separation of a single leadframe handler assembly, holding a damaged leadframe, from the leadframe transport carousel keeps the remainder of the leadframe handler assemblies on the leadframe transport carousel for processing. And finally, when a leadframe must be removed from the leadframe transport for inspection, the physical handling bag an operator only occurs with the leadframe handler assembly thus minimizing additional stresses imparted to the leadframe itself. These and other features of the independent leadframe transport and method will become apparent in the following detailed explanation of the preferred embodiments. 
     Referring first to FIG. 2, a perspective side view of equipment  10  in a preferred embodiment of the present invention is shown. The equipment  10  comprises the following main components: A main drive unit  14  having at least one tool-drive unit  12 . In a preferred embodiment, as shown herein, the equipment  10  has three tool-drives  12   a, b  and  c . However the number of individual tool-drives used in the equipment  10  is variable depending on the needs and desires of the end user. While the preferred embodiment shown herein has three tool-drives,  12   a, b  and  c , the number of tool-drives may be as few as one, and as many as six. The equipment  10  is further comprised of a stack unit  28  coupled to the main drive unit  14 , and a leadframe transport carousel  20  coupled atop the stack unit  28  and positioned proximate to the tool(s)  22 . 
     In the preferred embodiment, the stack unit  28  is translationally coupled to the main drive unit  14  so that the leadframe transport carousel  20  may be selectively positioned within the tool-drive(s)  12  in the in-tool position as shown herein. Reference to FIG. 3 will show the stack unit  28  translated such that the leadframe transport carousel  20  is without the tool-drive(s)  12  in the out-tool position. Attention is directed to the stack unit  28 , hinge  16 , which couples the stack unit  28  to the main drive unit  14  at the lower extremities and provides for the translation feature of the stack unit  28  and its constituent parts, including the leadframe transport carousel  20 , between the in-tool position, shown in FIG. 2, and the out-tool position, shown in FIG.  3 . The hinge  16  is a key component in the leadframe transport and method for translating the leadframe transport carousel  20  from the in-tool position in which the leadframe handler assemblies are within the tool-drives  12 , to the out-tool position in which the leadframe handler assemblies are without the tool-drive(s)  12 . In a preferred embodiment, the translation is a rotation about the hinge  16 . Alternative embodiments addressing the translation of the stack unit may also include however, a linear translation of the stack unit  28  between the in-tool position, and the out-tool position (not shown herein); or a rotation of the stack unit  28  about a vertical axis parallel to the main drive unit  14  (not shown herein). 
     Referring to FIGS. 2 and 3, it is shown that each tool-drive  12   a, b  and  c  is also comprised of a tool set  22   a, b,  and  c . Each tool set  22   a, b,  and  c  has an upper tool U 1 ,  2 , and  3 ; and a lower tool B 1 ,  2 , and  3  respectively. The leadframe transport carousel  20  is positioned between the upper and lower tools U 1 - 3  and B 1 - 3  when in the in-tool position. Those skilled in the art will recognize that, as previously discussed herein, the number of tool sets  22  is variable depending on the number of tool-drives  12  in a desired embodiment. 
     The stack unit  28  is comprised of five leadframe magazines M which can be in one of the following positions:  34 ,  36 ,  38 ,  40 ,  42  or  44  (shown more clearly in FIG.  1 ). Positioned atop the leadframe magazines M at position  34  and  44  (shown more clearly in FIG. 1) are the on-load buffer  30 , and the off-load buffer  32  respectively. The stack unit  28  is also comprised of the leadframe transport carousel  20  and support and drive equipment  26 , the details of which are not shown herein, but may be accomplished in a variety of methods by those skilled in the art. 
     Referring to FIG. 1, a perspective top view of the leadframe transport carousel  20  and on-load and off-load buffers  30  and  32  of the present invention in a preferred embodiment are shown. The on-load buffer  30  is supplied with to-be-processed leadframes  200  from the magazine M at position  34 . The off-load buffer  32  deposits processed leadframes  300  sequentially into the magazine M on position  44 . 
     The actual operational sequence is that from the magazine M at position  34  the on-load buffer  30  will be filled with to-be-processed leadframes  200 . From the top of the on-load buffer  30  the to-be-processed leadframes  200  are picked-up and placed into one of the leadframe handler assemblies G 1 - 6 . The leadframes transport carousel  20  transports the leadframe handler assemblies Gl- 6 , with the to-be-processed leadframes  200  in them, through the tool-drive(s)  12  (see FIG.  2 ). The leadframe handler assembly Gl- 6  is transported by the leadframe transport carousel  20  till the leadframe handler assembly G 1 - 6  is above the off-load buffer  32 , the leadframe handler assembly G 1 - 6  will release the now processed leadframe  300  into the off-load buffer  32 . 
     At the moment that the last to-be-processed leadframe  200  is moved into the on-load buffer  30  from the magazine M beneath it, the first processed leadframe  300  is still in the bottom of the off-load buffer  32 . i.e. because both the on-load buffer  30  and the off-load buffer  32  are longer than half a magazine M, at the point when the on-load buffer  30  has just received the last to-be-processed leadframes  200  from the magazine M beneath it, the quantity of to-be-processed leadframes  200  in the buffer  30  will constitute one half of the capacity of a magazines M. Therefore, the remaining leadframes, both to-be-processed and processed will be either on the leadframe transport carousel  20 , or in the off-load buffer  32 . This is the moment that the now empty magazine M at position  34  moves to position  44  beneath the off-load buffer  32 . 
     Following the shift of the magazine M the remainder of the to-be-processed leadframes  200  are transported through the tool-drives  12 , processed into processed leadframes  300 , which are transported back to a position above the off-load buffer  32  where they are released into the off-load buffer  32 , which in turn places the processed leadframes  300  into the magazine M at position  44 . This is a very unique feature of this leadframe transport in that the processed leadframes  300  are placed back in the same magazine M they were in when they were to-be-processed leadframes  200 . 
     At the moment that the magazine M at position  34  has moved to position  44  the magazines M at position  36  and  38  move to position  34  and  36 . A new magazines, M with to-be-processed leadframes  200 , is now under the on-load buffer  30  ready to supply new to-be-processed leadframes  200  for processing. Now the magazine M at position  40  will move to position  38  (see FIG.  2 ). 
     When the processed leadframes  300  are all in the magazine M at position  44 , the to-be-processed leadframes  200  in the new magazine M at position  34  are in process and the magazines M on position  42  and  44  move to position  40  and  42  (see FIG.  2 ). 
     In this fashion the on-load and off-load buffers  30  and  32  are to kept supplied and emptied respectively. The on-load buffer  30  supplies to-be-processed leadframes  200  to the leadframe transport carousel  20  above it. As shown, leadframe handler assemblies G 2 - 3 , located in the process area  220 , are gripping to-be-processed leadframes  200   a-b  previously loaded from the on-load buffer  200 . Leadframe handler assembly G 1 , located at the right end of the process area  220  and leadframe handler assemblies G 4 - 6 , located in the return area  330 , are shown gripping processed leadframes  300   a-d  respectively which the leadframe transport carousel  20  will deposit into the off-load buffer  32  beneath the leadframe transport carousel  20 . 
     In the way described above the magazine transport (not shown herein) is also a carousel. The start situation is with magazines M at the positions  34 ,  36 ,  38 ,  40  and  42  filled with to-be-processed leadframes  200 . After five magazine carousel cycles there are five magazines M at the positions  36 ,  38 ,  40 ,  42  and  441  filled with processed leadframes  300  with a unique feature being that all the processed leadframes  300  are in the same magazine M they were in when they were to-be-processed leadframes  200 . 
     The leadframe transport carousel  20  (see FIG.  1 ). is preferably comprised of: a main track  70  having leadframe handler tracks  82  and  80 ; an on-load turning point assembly  56  having leadframe handler tracks  72  and  74  and a turning point drive shaft  58 ; an off-load turning point assembly  54  having leadframe handler tracks  76  and  78  and a turning point drive shaft  60 ; a plurality of leadframe handler assemblies G 1 - 6  coupled to the leadframe transport carousel  20  each having a release mechanism R 1 - 6  respectively, wherein each release mechanism R 1 - 6  detachably couples each leadframe handler assembly G 1 - 6  to leadframe handler tracks  72 ,  74 ,  76 ,  78 ,  80  and  82  of the leadframe transport carousel  20 ; and pitch strips  50  and  52  that are positioned, alongside the main track  70  which serve to pickup and advance each of the leadframe handler assemblies G 1 - 6  a pitch position at a time as indexed by the main drive unit  14  (see FIGS.  2 - 3 ). The leadframe transport carousel  20  is adapted and configured to move a plurality of leadframe handler assemblies G 1 - 6  sequentially through at least one tool-drive  22  (see FIGS. 2-3) within a process area  220 , and then through a return area  330 . The sequential movement of the leadframe transport carousel  20  is indexed with the tool-drives  12   a-c  operation by a mechanical drive (not shown herein) from the main drive unit  14  main shaft (not shown) as will be understood by those well skilled in the art. 
     Referring now to FIGS. 4-8, and  4   a - 8   a , planar views of a preferred embodiment of the leadframe transport carousel  20  in sequential positions are shown. FIGS. 4-8 show an top view of the leadframe transport carousel  20  as it is indexed through a sequence of process pitch movements. FIGS. 4 a - 8   a  show corresponding side views of the leadframe transport carousel  20  from the off-load turning point assembly  54  end as it is indexed through a sequence of process pitch movements. 
     Referring to FIGS. 4-4 a , the leadframe transport carousel  20  is at rest. Leadframe handler assemblies G 4 - 6  are shown coupled to the leadframe handler track  80 ; and leadframe handler assemblies G 1 - 3  are shown coupled to the leadframe handler track  82 ; the pitch strip  50  is lowered (see FIG. 4 a ) and positioned to the on-load end overlapping the on-load turning point assembly  56 ; the pitch strip  52  is also lowered (see FIG. 4 a ) and positioned to the off-load end overlapping the off-load turning point assembly  54 . 
     Referring to FIGS. 5-5 a , the leadframe transport carousel  20  is shown initiating an indexed process pitch sequence. The pitch strips  50  and  52  rise up (see FIG. 5 a ) and lift the leadframe handler assemblies G 1 - 6  off of the leadframe handler tracks  80  and  82  to which they were coupled by the release mechanisms R 1 - 6 . 
     Referring to FIGS. 6-6 a , the pitch strip  50  indexes one process pitch length to the right, towards the off-load turning point assembly  54  (see FIG. 6) thus placing the leadframe handler assembly G 1  over the off-load turning point assembly  54  and advancing leadframe handler assemblies G 2 - 3  one process pitch position to the right; and at the same time, the pitch strip  52  indexes one process pitch length to the left, towards the on-load turning point assembly  56  thus placing the leadframe handler assembly G 4  over the on-load turning point assembly  56  and advancing leadframe handler assemblies G 6 - 5  one process pitch position to the left. Simultaneously with the process pitch movement of the pitch strips  50  and  52  in their upper position, both the on-load and off-load turning point drive shafts  58  and  60  rotate in the counter-clockwise direction 180°. 
     Referring to FIGS. 7-7 a , the pitch strips  50  and  52  now descend; and the leadframe handler assemblies&#39; G 2 - 3 —release mechanisms R 2 - 3  couple to the leadframe handler track  82 ; the leadframe handler assembly&#39;s G 1 —release mechanism R 1  couples to the leadframe handler track  78  which is atop the off-load point turning assembly  54 ; the leadframe handler assembly&#39;s G 6 — 5  release mechanisms R 6 - 5  couple to the leadframe handler track  80 ; and the leadframe handler assembly&#39;s G 4 —release mechanism R 4  couples to the leadframe handler track  72  which is atop the on-load point turning assembly  56 . 
     Referring to FIGS. 8-8 a , the pitch strip  50  indexes one process pitch length to the left (see FIG.  8 ), towards the on-load turning point assembly  56  thus positioning the pitch strip  50  for the start of the next indexing sequence; and the pitch strip  52  indexes one process pitch length to the right, towards the off-load turning point assembly  54  thus positioning the pitch strip  53  for the start of the next indexing sequence. During this time frame in which the pitch strips  50  and  52  are moving, the off-load point turning assembly  54  rotates 180° clockwise thus rotating the attached leadframe handler assembly Gl out of the process area  220  (see FIG. 1) and into the return area  330  (see FIG.  1 ); and the on-load point turning assembly  56  rotates 180° clockwise thus rotating the attached leadframe handler assembly G 4  out of the return area  330  (see FIG. 1) and into the process area  220  (see FIG.  1 ). 
     The pitch strips  50  and  52  and the turning point assemblies  54  and  56  are now ready for another indexed process pitch sequence. As previously discussed for FIGS. 5-5 a  and  6 - 6   a , the pitch strips  50  and  52  will again rise and lift the leadframe handler assembly G 1  off of the leadframe handler track  78 , leadframe handler assemblies G 6 - 5  off of the leadframe handler track  80 , leadframe handler assembly G 4  off of the leadframe handler track  72 , and leadframe handler assemblies G 3 - 2  off of the leadframe handler track  82  to which the leadframe handler assemblies G 1 - 6  were coupled by the release mechanisms R 1 - 6 . 
     Although the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that changes in form and detail may be made therein without departing from the spirit and scope of the invention.