Abstract:
The present invention relates to electronic packaging and a method for manufacturing the same. According to an embodiment of the present invention, an emulator chip package is designed and assembled such that a bottom portion of the emulator chip package is approximately the same electronic package used to package the target chip. Additionally, a top portion of the emulator chip package is approximately a slightly modified version of the same type of package used to package the target chip. According to an embodiment of the present invention, the top portion of the emulator chip package is attached to the bottom portion of the emulator chip package. The lead connector pins of the top portion of the package preferably leads up, while the connector pins of the bottom portion of the package preferably leads down.

Description:
FIELD OF THE INVENTION SECTION 
     The present invention relates to testing and simulation of a microprocessor chip. In particular, the present invention relates to an emulation package for an emulation chip. 
     BACKGROUND OF THE INVENTION 
     A modern integrated circuit board typically includes multiple microprocessor chips. An example of an integrated circuit (IC) board  100  with a microprocessor chip  102  is shown in FIG.  1 . Microprocessor chip  102  actually represents a microprocessor chip contained in an electronic package. An example of such a chip is a commercial microprocessor chip manufactured by Siemens. 
     Once the microprocessor chip  102  is placed on the IC board  100 , it is typically tested to ensure proper performance. However, since the actual chip is typically contained in an electronic package, the microprocessor chip  102  is generally inaccessible. In order to analyze the performance of a chip  102  embedded in an IC board  100 , an “in-circuit emulator” is commonly used to emulate the processes of the target chip  102 . An “in-circuit emulator” is typically a box of hardware (or plug-in card) which emulates the microprocessor in a target system via a cable connection. The in-circuit emulator can execute code in the target system&#39;s memory (typically erasable programmable read only memory (EPROM) or random access memory (RAM)), or it can execute code which has been downloaded to the emulator. 
     The emulator may monitor everything that is happening in the microprocessor, such as monitoring the contents of registers. For example, the emulator may be asked to check a write cycle to an EPROM&#39;s area of memory space to provide a listing of the last one hundred instructions executed before a write-to-EPROM error. 
     FIG. 2 shows a block diagram of an example of an in-circuit emulator. FIG. 2 includes an IC board  100  coupled with a connector board  202 . IC board  100  would be coupled to the target microprocessor chip under normal conditions. However, during testing and emulation, IC board  100  may be coupled with connector board  202  via a connector  208 . The purpose of connector board  202  is to facilitate a connection with an in-circuit emulator  200 . 
     In-circuit emulator  200  is shown to include connectors  206  and an emulator chip  204 . In-circuit emulator  200  may be any in-circuit emulator, such as those manufactured by HiTex or Nohau. Emulation chip  204  typically has the same interface with the environment as the target microprocessor chip ( 102  of FIG. 1) in order to emulate the same processes and functions that target chip  102  would perform. However, emulator chip  204  also typically facilitates extra signals which may be used to trace control and trace problems within emulator chip  204 . For example, a target microprocessor chip  102  may contain 100 to 200 connector pins for electronic signals, while emulator chip  204  designed to emulate target chip  102  may include more than 400 connector pins. In order to accommodate the extra connector pins for the signals used during testing, emulator chip  204  is typically very large. The need to accommodate the extra connector pins requires that emulator chip  204  be typically encased in a different sized and shaped electronic package than the target chip&#39;s package in order to accommodate the extra connectors. 
     Since emulator chip  204  is encased in a different package than target chip  102 , it is common for the two electronic packages to have an incompatible packaging footprint which typically makes it difficult, if not impossible, to directly place the emulator chip  204  onto IC board  100 . A packaging footprint may include factors such as the number of connector pins, the length of the connector pins, the geometry of the package, and distance between the connector pins (pitch). Since emulator chip  204  is typically not directly placed onto IC board  100 , long connector lines are typically required to connect emulator chip  204  with IC board  100 . An example of the connector line length is approximately five inches. These long lines undesirably slow down the speed of the system. 
     Another disadvantage of using conventional emulation chip packages is that only a very small number of emulation packages are typically produced. Accordingly, the manufacturing of specially designed emulation packages are typically very expensive since the cost of manufacturing is not absorbed in the volume of produced emulation packages. 
     It would be desirable to have an emulation chip package which can be manufactured at a reasonable cost. It would also be desirable to have an emulation chip package which has the same or compatible footprint as the target chip such that the emulation chip can be directly coupled to the IC board in place of the target chip. Additionally, it would be desirable to minimize the length of the connectors between the IC board and the emulation chip. The present invention addresses such needs. 
     SUMMARY OF THE INVENTION 
     The present invention relates to electronic packaging and a method for manufacturing the same. According to an embodiment of the present invention, an emulator chip package is designed and assembled such that a bottom portion of the emulator chip package is approximately the same electronic package used to package the target chip. Additionally, a top portion of the emulator chip package is approximately a slightly modified version of the same type of package used to package the target chip. According to an embodiment of the present invention, the top portion of the emulator chip package is attached to the bottom portion of the emulator chip package. Connector pins of the top portion of the package preferably leads up, while the connector pins of the bottom portion of the package preferably leads down. 
     The emulator chip package according to an embodiment of the present invention has approximately the same or compatible footprint as the package of the target chip and thus may directly replace the target chip on the IC board. Additionally, with the addition of the top portion of the emulator chip package, the emulator chip package will have double the number of connector pins as the target chip package. The extra connector pins of the emulator chip package may facilitate the extra signals required for testing and emulation. Alternatively, the extra pins may be used to connect to a printed circuit board which can facilitate extra signals required for emulation. 
     An electronic package for an emulation chip is presented according to an embodiment of the present invention. The electronic package comprises a first portion of the electronic package, wherein the first portion may be directly coupled with an integrated circuit board. A first set of contacts is coupled with the first portion, the first set of contacts being configured to conduct electrical signals. A second portion of the electronic package is also included, the second portion being coupled to the first portion. A second set of contacts is coupled with the second portion, the second set of contacts being configured to conduct electrical signals. 
     In another aspect of the present invention, a method for manufacturing an electronic package according to an embodiment of the present invention is presented. The method comprising providing a first electronic package, providing a second electronic package, and attaching the first and second electronic packages together to result in a resulting electronic package. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of an integrated circuit board. 
     FIG. 2 is a block diagram of an in-circuit emulator coupled with an integrated circuit board. 
     FIG. 3 is a block diagram of an emulator chip package according to an embodiment of the present invention. 
     FIG. 4 is a cross sectional view of an emulator chip package according to an embodiment of the present invention. 
     FIG. 5 is a cross sectional view of the emulator chip package coupled with a printed circuit board, according to an embodiment of the present invention. 
     FIG. 6 is a block diagram of a printed circuit board which may be used in conjunction with the emulator chip package according to an embodiment of the present invention. 
     FIG. 7 is a block diagram of an integrated circuit board with an emulator chip located directly on it according to an embodiment of the present invention. 
     FIG. 8 is a flow diagram of a method for manufacturing an emulator chip package according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description is presented to enable one of ordinary skill in the art to make and to use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiments will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and features described herein. 
     FIG. 3 is a block diagram of an emulator chip package according to an embodiment of the present invention. The emulator chip package  400  of FIG. 3 is shown to include a bottom portion  404 A of the package and a top portion  404 B of the package. Bottom portion  404 A is preferably the same package as the target chip package which encases the target microprocessor chip. There are many varieties of packages which may be used to encase a target microprocessor chip. For example, these microprocessor chip packages include packages manufactured by Advanced Micro Devices (AMD), Motorola, Texas Instruments (TI), Intel, and Siemens. An example of a range of the number of connector pins which may be included in a chip package is 40 to 240 pins. 
     Whatever package is used to encase the target microprocessor chip is preferably the same package that is used as bottom portion  404 A of the emulator chip package, according to an embodiment of the present invention. Selection of a package to be used as bottom portion  404 A should consider factors of cost, ease of manufacturing, functionality of the connector pins, and footprint being compatible with those of the target microprocessor chip. A package footprint is herein meant to include factors such as the number of connector pins, the length of the connector pins, the geometry of the package, and distance between the connector pins (pitch). 
     Using the same package as that of the target microprocessor chip would meet all of these criterias. A target microprocessor chip package is typically manufactured in large quantities, thus the additional cost of manufacturing one more for an emulator chip is quite small. A further advantage is that the footprint of bottom portion  404 A would be identical to the footprint of the target chip package. Accordingly, bottom portion  404 A could be directly placed on the IC board, replacing the target chip. 
     Alternatively, a package that is similar to the one used to encase the target microprocessor chip may be used as bottom portion  404 A. If a similar package is selected, it is preferred that the bottom portion  404 A of the emulator chip package have the same or compatible footprint to allow it to directly replace the target chip on the IC board. A compatible package footprint may be any footprint which allows the emulator chip package to directly replace the target chip on the IC board. It is also preferred that if bottom portion  404 A is not the same type of package used for the target chip, then it should also be a chip package that is commonly manufactured for another microprocessor chip to ensure ease of manufacturing and minimization of cost. 
     As shown in FIG. 3, bottom portion  404 A of the emulator chip package includes an emulator microprocessor chip  402  located inside bottom portion  404 A. Bottom portion  404 A also includes a set of connector pins  406 A surrounding the perimeter of bottom portion  404 A. 
     Top portion  404 B of the emulator chip package may be the same or similar package as that used for bottom portion  404 A, according to an embodiment of the present invention. Factors to consider for selection of top portion  404 B also include cost and ease of manufacturing, but the footprint does not have match the footprint of the target chip package since top portion  404 B does not directly couple to the IC board. A package used for the target chip meets these criterias, as does most packages manufactured for microprocessor chips. 
     Top portion  404 B includes a hole  408  which approximately matches the location of emulator microprocessor chip  402 . Upper portion  404 B also includes a set of connector pins  406 B around the perimeter of top portion  404 B. Connector pins  406 B of top portion  404 B are preferably angled up away from bottom portion  404 A. Likewise, it is preferable that connector pins  406 A of bottom portion  404 A are angled away from top portion  404 B. This angling can be accomplished by simply taking two conventional packages and facing them in opposite directions such that connector pins face away from each other. 
     Top portion  404 B and bottom portion  404 A are attached together such that a planar surface of top portion  404 B and a planar surface of bottom portion  404 A are attached together, preferably with their perimeters approximately aligned with each other. The attachment may be made with any bond commonly used in packaging technology, such as glue. Once top portion  404 B is attached to bottom portion  404 A, emulator chip package  400  will have approximately double the number of connector pins  406 A- 406 B than the number of connector pins located on the target chip package. The extra pins may be used for conducting the additional signals required during emulation and testing. 
     FIG. 4 is a cross sectional view of the emulator chip package  400  according to an embodiment of the present invention. Bottom portion  404 A is shown to include emulator microprocessor chip  402  connected to connector pins  406 A of bottom portion  404 A via connectors  450 . Emulator microprocessor chip  402  is also connected through connectors  450  to the top row of connector pins  406 B of top portion  404 B. 
     It is optional to slightly reduce the length of inner portion  452 A- 452 B of the top row of connector pins  406 B. If the inner portions  452 A- 452 B are shortened, then a connector device may attach connectors  450  between emulator microprocessor chip  402  and connector pins  406 B- 406 A in one session since the device would be able to reach the lower row of connector pins  406 A as well as the top row of connector pins  406 B. Once emulator microprocessor chip  402  has been placed within bottom portion  404 A through hole  408  of FIG. 3, connectors  450  are in place, and top portion  404 B and bottom portion  404 A have been attached, a lid  456  may be placed on top of top portion  404 B to enclose emulator microprocessor chip  402 . 
     A printed circuit board (PCB)  454 A with emulator connectors may be placed on top of emulator chip package  400  to facilitate communication to and from an emulation computer. PCB  454 A may be coupled to the emulator chip package  400  in any manner commonly used for coupling electrical packages to a PCB, such as soldering. Further details of PCB  454 A will later be discussed in conjunction with FIG.  6 . 
     FIG. 5 shows an alternate embodiment of the coupling between emulator chip package  400  and printed circuit board  454 B. Emulator chip package  400  may be connected to a connection board  456  which in turn is coupled with the printed circuit board  454 B. Connection board  456  simply facilitates connection between emulator chip package  400  and PCB  454 B. It channels signals between PCB  454 B and upper connector pins  406 B. Connection board  456  is shown to be connected to PCB  454 B through a connector  458 . Connector  458  may be a flexible connector such as a connector ribbon, or a rigid connector. An example of an appropriate connector ribbon is a connector ribbon manufactured by 3M or AMP. Connector  458  is preferably as short as possible. For example, the length of connector  458  may be approximately 3-5 inches. 
     FIG. 6 is a block diagram of a printed circuit board, such as printed circuit board  454 A of FIG. 4 and 454B of FIG.  5 . Printed circuit board (PCB)  454  is shown to include a connector and a bus driver  502  which facilitates communication to and from an emulation computer (not shown). Connector and bus driver  502  is also shown to be coupled with two trace memories  506 A- 506 B. These trace memories  506 A- 506 B may be dual port memories which read from one side and write from another. The specifics of trace memories  506 A- 506 B depend on various implementations. Examples of trace memories  506 A- 506 B may be random access memories (RAMs) with 128 by 10K or 256 by 10K bit width. 
     Trace memories  506 A- 506 B may perform a real-time trace to produce a log of instructions. For example, they may record every status information and clock information. Trace memories  506 A- 506 B receive data from emulator chip package  400  and are read from the emulation computer through connector and bus driver  502 . 
     Connector and bus driver  502  is also shown to be coupled with a program memory  504 . Program memory  504  receives instructions from the emulation computer through connector and bus driver  502 . The emulator chip then reads these instructions from program memory  504  during emulation of a target microprocessor chip. Examples of program memory  504  include a dual port RAM or erasable programmable memory (EPROM) with 256 Kb or 512 Kb. 
     FIG. 7 is a block diagram of an integrated circuit (IC) board  100  with an emulator chip package  400  (encasing an emulator chip) directly connected to IC board  100  according to an embodiment of the present invention. Emulator chip package  400  may be directly connected to IC board  100  in the same location as a target chip would have been connected to IC board  100 . Emulator chip package  400  would be coupled to an emulation computer (not shown) such that signals may be communicated to and from emulator chip package  400 . By being directly coupled to IC board  100 , long connection lines and extra connectors to connect to emulator chip package  400  may be avoided. 
     FIG. 8 is a flow diagram illustrating an example of a method according to an embodiment of the present invention for manufacturing an emulator chip package. The method shown in FIG. 8 is merely an example and many variations of the steps shown may be implemented. For example, the order of many of the steps may be changed and still produce the same effect. 
     The method exemplified in FIG. 8 begins with the inside length of top layer connector pins being shortened (step  600 ). For example, inside length  452 A- 452 B of the top layer connector pins  406 B of FIG. 5 are shortened. Two packages are then attached together (step  602 ). Preferably, the bottom package (i.e., the package that is to be directly coupled with the IC board) is the same or substantially similar to the package encasing a target microprocessor chip. As previously discussed, the top package (i.e., the package that is not intended to be directly coupled to the IC board) may also be the same or similar to the package used for the target microprocessor chip. 
     An emulator microprocessor chip is then installed inside the two attached packages, resulting in a combined package (step  604 ). Connector pins are then bonded to the emulator microprocessor chip from the combined package (step  606 ). A lid is then installed to close the resulting combined package (step  608 ). 
     Although the present invention has been described in accordance with the embodiment shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiment and these variations would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.