Abstract:
A semiconductor device is disclosed including die bond pads which are heightened to allow wire bonding of offset stacked die even in tight offset configurations. After a first die is affixed to a substrate, one or more layers of an electrical conductor may be provided on some or all of the die bond pads of the first substrate to raise the height of the bond pads. The conductive layers may for example be conductive balls deposited on the die bond pads of the first substrate using a known wire bond capillary. Thereafter, a second die may be added, and wire bonding of the first die may be accomplished using a known wire bond capillary mounting a wire bond ball on a raised surface of a first semiconductor die bond pad.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The following application is cross-referenced and incorporated by reference herein in its entirety: 
         [0002]    U.S. patent application Ser. No. ______ [Attorney Docket No. SAND-01227US1], entitled “EXTENDER STRIP AND TEST ASSEMBLY FOR TESTING MEMORY CARD OPERATION,” by Alan Chiou et al., filed concurrently herewith. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    Embodiments of the present invention relate to a system and method of testing operation of a memory card with an electronic host device. 
         [0005]    2. Description of the Related Art 
         [0006]    The strong growth in demand for portable consumer electronics is driving the need for high-capacity storage devices. Non-volatile semiconductor memory devices, such as flash memory storage cards, are becoming widely used to meet the ever-growing demands on digital information storage and exchange. Their portability, versatility and rugged design, along with their high reliability and large capacity, have made such memory devices ideal for use in a wide variety of electronic devices, including for example digital cameras, digital music players, video game consoles, PDAs and cellular telephones. 
         [0007]    There is an ever-present push to provide greater device capability in a smaller form factor. As a result, some devices have had to resort to positioning the memory card slot somewhere within the interior of the device. For example, as shown in prior art  FIG. 1 , in order to provide the most compact form factor, some cellular telephone manufacturers have resorted to providing a telephone  20  having a memory card slot  22  positioned beneath a cover  24 . It is also known in cellular telephones and other electronic devices to position the memory card slot  22  beneath the battery slot. Thus, both the cover and battery must be removed to allow access to the memory card slot  22 . Still other electronic devices have the memory card slot positioned elsewhere within the interior of the device so as to be generally inaccessible when the device is assembled and operational. 
         [0008]    One drawback to having the memory card slot positioned within the interior of the device is that it is not accessible to test equipment used to test the operation of the memory card, electronic device and/or the exchange of signals therebetween. In particular, prior to a device manufacturer shipping a line of electronic devices, the manufacturer will typically perform fault testing on one or more of the devices. This fault test may include transferring data between the portable memory card positioned within the card slot  22  and the electronic device to ensure proper data transfer. The testing equipment may include a debugging apparatus, such as a logic analyzer and/or an oscilloscope, so that, when a problem is detected, the fault may be debugged and the specific source of the problem identified. 
         [0009]    Such testing operations are carried out by connecting to the signal contact pads in the memory card slot of the host device and testing the device during its normal operation. However, with designs where the memory card slot is enclosed within the housing, for example buried beneath the battery and/or cover, it is not possible to access the memory card slot in order to perform the fault testing. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention, roughly described, relates to a system and method for testing operation of a memory card with an electronic host device. The present system is particularly useful for testing a host device having a memory card slot buried beneath a cover and possibly one or more other host device components when the host device is operational. The system includes a flat flexible cable, or strip, for electrically coupling between the memory card slot in a host device and a test assembly. An end of the strip may include contact pads for mating with the contact pads within the host device card slot. The same end may further include a rigid member for ensuring proper alignment and contact between the strip contact pads and the card slot contact pads. In embodiments, the rigid member may be the same size and shape as a memory card for which the host device memory card slot is configured. 
         [0011]    The opposite end of the strip may be connected to the test assembly. The test assembly may have a card slot of accepting an external memory card, and a debug header for receiving a cable connected to a debug apparatus such as a logic analyzer and/or an oscilloscope. In embodiments, the external card slot on the test assembly may be configured to accept the same or different type of memory card as the host device card slot. 
         [0012]    In operation, once all components are connected, signals may be exchanged between the host device and the external memory card plugged into the test assembly. The debug header may extract signals sent from the host device to the external memory card. Those signals may be transferred to the debugging apparatus, which can then analyze the integrity of the respective signals. Thus, according to the present invention, the operation of a memory card with the host device, and the exchange of signals between the host device and a memory card, may be tested and debugged even though the memory card slot is inaccessible while the host device is operational. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a conventional electronic device having a memory card slot buried beneath the device cover and possibly one or more additional components. 
           [0014]      FIG. 2  is a perspective view of an electronic device together with a strip and test assembly according to the present invention. 
           [0015]      FIG. 3  is a bottom view of the strip and a portion of the test assembly according to the present invention. 
           [0016]      FIG. 4  is a perspective view of a strip according to the present invention having an end affixed within the memory card slot of the electronic device. 
           [0017]      FIG. 5  is a perspective view of a first end of a strip according to the present invention affixed within a sealed electronic device and a second end of the strip affixed to a test assembly. 
           [0018]      FIG. 6  is a perspective view as in  FIG. 5 , with an external memory card and debug apparatus cable affixed to the test assembly. 
           [0019]      FIG. 7  is a flow chart of the assembly and operation of an embodiment of the present invention. 
           [0020]      FIG. 8  is an electrical schematic diagram of test assembly according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Embodiments will now be described with reference to  FIGS. 2 through 8 , which relate to a system and method of testing operation of a memory card with an electronic host device. It is understood that the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the invention to those skilled in the art. Indeed, the invention is intended to cover alternatives, modifications and equivalents of these embodiments, which are included within the scope and spirit of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be clear to those of ordinary skill in the art that the present invention may be practiced without such specific details. 
         [0022]    Referring initially to the exploded perspective view of  FIG. 2 , there is shown an electronic device  100  including a memory card slot  102  provided within the interior of device  100 . Device  100  may be any of a variety of electronic devices including a slot for receiving a memory card. Such devices include, but are not limited to, cellular telephones, digital cameras, digital music players, video game consoles, PDAs, and handheld computers. Card slot  102  may be of a type to receive any of a variety of known memory card configurations, such as for example a micro SD memory card, manufactured by San Disc Corporation, Milpitas, Calif. Card slot  102  may be accessible upon removal of a cover  104 . It is contemplated that card slot  102  may be buried beneath one or more additional components of host device  100 , such as for example a battery powering device  100 . 
         [0023]    Referring now to the perspective view of  FIG. 2  and the bottom view of  FIG. 3 , a flexible electrical connector, or strip,  110  may be provided in accordance with the present invention having a first end  112  and a second end  114  opposite end  112 . Flexible strip  110  may be flat flexible cable (FFC), and may include a plurality of electrical traces  116  laminated within an insulator such as for example polyester. It is understood that the insulator may be other than polyester in alternative embodiments of the present invention. The number of traces laminated within electrical strip  110  may match the number of contact pads within card slot  102 . It is understood that the number of traces within strip  110  may be less than or greater than the number of contact pads in card slot  102  in alternative embodiments. The flexible strip  110  may have a width of for example be one-third of an inch to two-thirds of an inch and may include electrical traces having a pitch of 0.5 millimeters. The width of strip  110  may be less than one-third inches and greater than two-thirds inches, and the pitch may be less than or greater than 0.5 millimeters, in alternative embodiments. Flexible strip  110  may have a substantially flat profile so as to be able to extend from the interior of device  100  to the exterior of device  100  when the device is fully assembled with cover  104  affixed in position on device  100 . 
         [0024]    End  112  of strip  110  may include exposed electrical contact pads  118  for mating with the contact pads within card slot  102 . Similarly, end  114  may include exposed electrical contact pads  120  for mating with connector pins in a testing apparatus as explained hereinafter. 
         [0025]    First end  112  may further include a rigid member  124  mounted to strip  110  on a side of strip  110  opposite that including exposed contact pads  118 . Rigid member  124  may be mounted using a known adhesive, have for example low outgassing and wear properties over time. Rigid member  124  is sized to fit within card slot  102  and is provided to facilitate contact between contact pads  118  on strip  110  and the contact pads within card slot  102 . 
         [0026]    In an embodiment, rigid member  124  may have the same footprint and shape as the memory card for which card slot  102  is configured. Thus, where card slot  102  accepts a micro SD card, rigid member  124  may have the outline of a micro SD card (as shown for example in  FIG. 3 ). It is understood that rigid member  124  may have other shapes in alternative embodiments, with the provision that rigid member  124  ensure a proper alignment and contact of contact pads  118  with the contact pads within the card slot  102 . Rigid member  124  may be formed of any of various rigid, electrically insulative materials, such as for example polycarbonate and other plastics. In an alternative embodiment, it is possible that rigid member  124  may be formed of metal or another conductor, where the adhesive used to affix rigid member  124  to strip  110  is an electrical isolator. 
         [0027]    The length of strip  110  (the distance between end  112  and end  114 ) may vary in alternative embodiments of the present invention, and may for example be between a half inch and four inches, and in further embodiments be between one and two inches. It is understood that the length of strip  110  may be shorter than one half inch and longer than four inches in further embodiments of the present invention. 
         [0028]    End  114  of strip  110  may mate with a connector  130  in a testing assembly  132 . Such connectors are commercially available for example from Molex Corp. having headquarters in Lisle, Ill. Test assembly  132  includes an external card slot  134  for receiving an external memory card as explained hereinafter. Test assembly  132  includes a debug header  136  connecting the test assembly  132  to a debugging apparatus, such as for example a logic analyzer or an oscilloscope (not shown) as are known in the art. End  114  of strip  110  may be a ZIF (zero insertion force) connector for mating within connector  130 . Connector  130  connects the signal traces within strip  110  both to respective contact pads within external card slot  134 , and with electrical terminals of debug header  136 . 
         [0029]    Referring now to  FIG. 4 , the rigid member  124  affixed to strip  110  may be inserted into card  102  in host device  100 . Member  124  ensures proper alignment and contact between contact pins  118  in strip  110  and the contact pads within the slot  102  of host device  100 . It is understood that rigid member  124  may be omitted in alternative embodiments and other mechanisms be provided (as part of strip  110  and/or within slot  102 ) to ensure proper alignment and contact of contact pins  118  with the contact pads within the card slot  102 . When end  112  of strip  110  is connected within card slot  102 , and end  114  of strip  110  is connected to the test assembly  132 , the electrical traces  116  within strip  110  communicate electrical signals between the host device and the test assembly. 
         [0030]    Referring now to the perspective views of  FIGS. 5 and 6 , once the end  112  of strip  110  is mated within slot  102 , the cover  104  as well as a battery or any other components may be assembled onto the host device to enable operation of the host device  100 . As strip  110  is flat and flexible, it can bend as necessary so that end  112  remains seated within slot  102  while opposite end  114  extends outside of the sealed host device  100 . 
         [0031]    As is also shown in the perspective views of  FIGS. 5 and 6 , external card slot  134  of test assembly  132  may receive an external memory card  140 , and debug header  136  may accept a cable  142  connecting test assembly  132  with one or more debug devices such as a logic analyzer and/or an oscilloscope. 
         [0032]    Memory card  140  may be the same type of memory card that is accepted within slot  102  within host device  100 . In alternative embodiments, external memory card  140  may be different than the memory card accepted within card slot  102  in device  100 . Thus for example where slot  102  is configured to receive a micro SD card, slot  134  may be configured to receive a mini SD card, an SD card or a variety of other memory cards. Additionally, slot  134  may accept an adapter which would allow a single slot  134  to operate with any of a variety of different configurations of external memory card  140 . 
         [0033]    The operation of the present invention will now be described with reference to the flow chart of  FIG. 7 . In step  200 , first end  112  of flex strip  110  is inserted into card slot  102  within host device  100 . Cover  104  and any other components are removed as necessary to allow insertion of rigid member  124  in the card slot  102 . In a step  202 , host device  100  may be assembled into an operational configuration. This may include replacing a battery or other component over the internal card slot  102 , and affixing the cover  104  in position on device  100 . 
         [0034]    In a step  204 , second end  114  may be inserted into test assembly  132 . An external memory card  140  may then be inserted into external card slot  134  in a step  206 . In step  208 , the debug cable  142  may be affixed to debug header  136 . In alternative embodiments of the invention, step  208  may be skipped and no debug apparatus affixed to test assembly  132 . In such embodiments, test assembly  132  and strip  110  may simply be used to test the exchange signals between an external memory card  140  and host device  100 . 
         [0035]    The device may be powered on in a step  212 , and signals may be exchanged between the external memory card  140  and the host device  100  in a step  214 . It is understood that the order of the above-described steps is not critical and may be performed in a different order in alternative embodiments. For example, step  212  of powering on the host device could be performed before step  204  of inserting the second end of flexible strip  110  into test assembly  132 . 
         [0036]    In step  216 , strip  110  and test assembly  132  may be used to test and debug the signal exchange between host device  100  and the external memory card  140 . Thus, according to the present invention, the operation of a memory card with the host device, and the exchange of signals between the host device and a memory card, may be tested and debugged even though the memory card slot is inaccessible while the host device is operational. 
         [0037]    Step  216  is explained in greater detail with respect to the schematic diagram of  FIG. 8 . Once all components are connected, signals may be exchanged between external memory card  140  and host device  100 . Debug header  136  may extract signals sent from host device  100  to the external memory card. Those signals may be transferred to a debugging apparatus such as a logic analyzer and/or an oscilloscope. The debugging apparatus can then analyze the integrity of the respective signals transferred to and/or from device  100 . The logic analyzer can access individual contact pads within the host device memory card slot  102 , and can accordingly locate the source of a problem in the event the test detects a faulty signal exchange. 
         [0038]    While embodiments of the present invention are particularly useful for testing the exchange of signals to and/or from a host device where the memory card slot is inaccessible, it is understood that the present invention may also be used with a card slot which is directly accessible from outside of the device. In such embodiments, the rigid member  124  on end  112  may be inserted directly into card slot  102  without having to remove cover  104  or any other components from host device  100 . 
         [0039]    While strip  110  and test assembly  132  have been described above as a system for testing the operation of a memory card with a host device, it is understood that strip  110  and assembly  132  may have other uses in further embodiments of the present invention. For example, in one such further embodiment, the above-described set up may be used to load software and/or data from an external memory card  140  onto host device  100 . After the software and/or data are loaded, the above-described assembly may be used to test the exchange of signals between device  100  and external memory card  140 . Alternatively, in this embodiment, the test procedure may be omitted and strip  110  and assembly  132  simply used to load software and/or information onto host device  100 . 
         [0040]    In the embodiments described above, rigid member  124  is used as a “dummy” memory card to facilitate the alignment and connection of first end  112  within card slot  102  in host device  100 . In a further alternative embodiment, rigid member  124  may in fact be an operational memory card affixed to strip  110  and fitting within slot  102 . In such an embodiment, flexible strip  110  may not be used to transfer electrical signals, but rather may be used as a support to facilitate automated insertion of the memory card into card slot  102  in device  100 . 
         [0041]    The foregoing detailed description 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. Many modifications and variations are possible in light of the above teaching. The described embodiments were chosen in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.