Abstract:
The packaging architecture for a multiple array transceiver using a flexible cable of the present invention provides a 90-degree transition between an optical signal input at a communications chassis bulkhead and an interior board within the communications chassis. The packaging architecture system comprises a forward vertical carrier having an optical converter, a paddle card, a flexible cable operably connected between the forward vertical carrier and the paddle card, and a rearward horizontal I/O block operably connected to the paddle card, the rearward horizontal I/O block oriented about 90 degrees from the forward vertical carrier. The multiple array transceiver makes the 90-degree transition within a narrow gap established by industry and manufacturer standards. The multiple array transceiver further provides cooling through a heat sink.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority to U.S. patent application Ser. No. 09/956,771 filed on Sep. 20, 2001 entitled “Fiber Optic Transceiver, Connector, And Method of Dissipating Heat” by Johnny R. Brezina, et al., the entire disclosure of which is incorporated by reference, herein.  
         [0002]    This application also relates to the following applications, filed concurrently herewith:  
         [0003]    “Optical Alignment In A Fiber Optic Transceiver”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010689US1);  
         [0004]    “External EMI Shield For Multiple Array Optoelectronic Devices”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010690US1);  
         [0005]    “Packaging Architecture For A Multiple Array Transceiver Using A Continuous Flexible Circuit”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010591US1);  
         [0006]    “Flexible Cable Stiffener for An Optical Transceiver”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010729US1);  
         [0007]    “Enhanced Folded Flexible Cable Packaging for Use in Optical Transceivers, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010727US1);  
         [0008]    “Apparatus and Method for Controlling an Optical Transceiver”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010728US1);  
         [0009]    “Internal EMI Shield for Multiple Array Optoelectronic Devices”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010730US1);  
         [0010]    “Multiple Array Optoelectronic Connector with Integrated Latch”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010731US1);  
         [0011]    “Mounting a Lens Array in a Fiber Optic Transceiver”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010733US1);  
         [0012]    “Packaging Architecture for a Multiple Array Transceiver Using a Flexible Cable and Stiffener for Customer Attachment”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010735US1);  
         [0013]    “Packaging Architecture for a Multiple Array Transceiver Using a Winged Flexible Cable for Optimal Wiring”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010736US1); and  
         [0014]    “Horizontal Carrier Assembly for Multiple Array Optoelectronic Devices”, by Johnny R. Brezina, et al. (IBM Docket No. AUS920010763US1). 
     
    
     
       TECHNICAL FIELD  
         [0015]    The technical field of this disclosure is computer systems, particularly, a packaging architecture for a multiple array transceiver using a flexible cable.  
         BACKGROUND OF THE INVENTION  
         [0016]    Optical signals entering a communications chassis can be converted to electrical signals for use within the communications chassis by a multiple array transceiver. The configuration of optical signal connections entering the communications chassis and the customer&#39;s circuit boards within the chassis require a 90-degree direction change in signal path from the optical to the electrical signal. This 90-degree configuration is required due to the right angle orientation between the customer&#39;s board and the rear bulkhead of the chassis. Existing multiple array transceiver designs use a number of small parts, such as tiny flexible interconnects with associated circuit cards and plastic stiffeners, to make the 90-degree transition. The size and number of the parts increases manufacturing complexity and expense.  
           [0017]    In addition, existing multiple array transceivers are limited in the number of electrical signal paths they can provide between the optical input and the customer&#39;s board. It is desirable to provide as many electrical signal paths as possible, because optical fiber can typically provide a greater information flow rate than electrical wire. Industry and company standards further limit the space available for signal paths from the optical input to the customer&#39;s board, limiting the space to a narrow gap.  
           [0018]    Thermal considerations may also limit the signal carrying capacity of current multiple array transceivers. Heat is generated by electrical resistance as the signals pass through the conductors and as the signals are processed by solid-state chips within the transceivers. Limitations on heat dissipation can limit the data processing speed and reduce transceiver reliability.  
           [0019]    It would be desirable to have a packaging architecture for a multiple array transceiver using a folded flexible cable that would overcome the above disadvantages.  
         SUMMARY OF THE INVENTION  
         [0020]    The packaging architecture for a multiple array transceiver using a flexible cable of the present invention provides a 90-degree transition between an optical signal input at a communications chassis bulkhead and an interior board within the communications chassis. The packaging architecture system comprises a forward vertical carrier having an optical converter, a paddle card, a flexible cable operably connected between the forward vertical carrier and the paddle card, and a rearward horizontal I/O block operably connected to the paddle card, the rearward horizontal I/O block oriented about 90 degrees from the forward vertical carrier. The multiple array transceiver makes the 90-degree transition within a narrow gap established by industry and manufacturer standards. The multiple array transceiver further provides cooling through a heat sink.  
           [0021]    One aspect of the present invention provides a packaging architecture for a multiple array transceiver providing a 90-degree transition between the customer&#39;s board and the rear bulkhead of the chassis.  
           [0022]    Another aspect of the present invention provides a packaging architecture for a multiple array transceiver with a reduced number of components for manufacturing ease and reduced cost.  
           [0023]    Another aspect of the present invention provides a packaging architecture for a multiple array transceiver providing an interconnection containing a very large number of signal paths in a narrow horizontal gap.  
           [0024]    Another aspect of the present invention provides a packaging architecture for a multiple array transceiver providing a thermally efficient design with heat flow to a heat sink.  
           [0025]    The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention, rather than limiting the scope of the invention being defined by the appended claims and equivalents thereof. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    [0026]FIG. 1 shows an isometric diagram of a forward vertical carrier made in accordance with the present invention;  
         [0027]    [0027]FIGS. 2A &amp; 2B show isometric diagrams of a forward vertical carrier in place in an I/O assembly made in accordance with the present invention; and  
         [0028]    [0028]FIGS. 3A &amp; 3B show isometric diagrams of a packaging architecture for a multiple array transceiver using a flexible cable made in accordance with the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0029]    The present invention is shown and described by the following description and figures, and is generally described in the order in which the individual components are assembled during manufacture.  
         [0030]    [0030]FIG. 1 shows an isometric diagram of a forward vertical carrier made in accordance with the present invention. The forward vertical carrier  48  comprises common substrate carrier  50 , laser die  52 , photodetector die  54 , laser drive amplifier (LDA)  56 , and transimpedance amplifier (TIA)  58 . Laser die  52  and photodetector die  54  are attached to a common substrate carrier  50  by using standard die bond epoxy material and technique as will be appreciated by those skilled in the art. The LDA  56  and TIA  58  are also die bonded to the substrate carrier  50  in close proximity to the laser die  52  and photodetector die  54  to provide short critical transmission interconnection wire bond lengths. The TIA  58  acts as the photodetector interface chip. The laser die  52  and photodetector die  54  are precisely aligned to provide optimum communication with a fiber optic cable which can be attached to the laser die  52  and photodetector die  54 .  
         [0031]    The laser die  52  and photodetector die  54  with their associated circuits perform as optical converters to convert a light signal coming into the transceiver to an electrical signal or convert an electrical signal from the transceiver to a light signal. In one embodiment, the optical converters can be lasers only, so that the transceiver only transmits optical signals. In another embodiment, the optical converters can be photodetectors only, so that the transceiver only receives optical signals. In other embodiments, the number of lasers and photodetectors can be predetermined to meet the number of transmit and receive channels desired.  
         [0032]    [0032]FIGS. 2A &amp; 2B, in which like elements have like reference numbers, show isometric diagrams of a forward vertical carrier in place in an I/O assembly made in accordance with the present invention. A flexible cable is provided between the forward vertical carrier and a paddle card, which connects to a rearward horizontal I/O block.  
         [0033]    The paddle card  74  can be any stiff material providing a connection for the flexible cable  60  and a platform for mounting electrical components. The paddle card  74  can be glass epoxy as typically used for printed circuit boards, but can be other materials, such as ceramics. In one embodiment, the paddle card  74  can be a two-sided printed circuit board. Typically, the paddle card  74  can comprise multiple signal layers for a plurality of signals, grounds, and power. Signal paths can also be provided from one side of the paddle card  74  to the other, and between signal layers, through vias.  
         [0034]    A flexible cable  60  comprises an electrical portion  62 , a transfer portion  64 , and an optical portion  66 . The flexible cable  60  electrically connects the paddle card  74  to the forward vertical carrier  48 , where the laser die  52  and photodetector die  54  are located. The flexible cable  60  can contain a plurality of conductors carrying a plurality of signals. The flexible cable  60  can be narrow to allow passage through a narrow gap. This allows the J-shaped interconnection between the rearward horizontal I/O block  76  and forward vertical carrier  48  to contain a very large number of signals in a narrow horizontal gap. The transfer portion  64  provides the 90 degree transition between the generally vertical forward vertical carrier  48  and the generally horizontal I/O block  76 , through the paddle card  74 .  
         [0035]    The flexible cable  60  can be attached to the paddle card  74  and the forward vertical carrier  48 . The optical portion  66  can be adhesively bonded to the face of the forward vertical carrier  48  where the electronic components are mounted. The optical portion  66  can be terminated in a profile around the LDA  56  and TIA  58  to match the shape of the LDA  56  and TIA  58  to provide ease of connection. The optical portion  66  can have wire bond pads in the area around the LDA  56  and TIA  58  to allow wire bonding to the dies.  
         [0036]    The electrical portion  62  can be adhesively bonded and wire bonded to the top face of the paddle card  74 , which provides the connections between the electrical portion  62 , receiver post amplifier  78 , and eeprom  80 . In an alternate embodiment, a hot bar bonded connection can be made between the electrical portion  62  and the paddle card  74 . The paddle card  74  provides both the flat horizontal surface for the solder ball  82  connection to the I/O block  76  and circuit attachment for the receiver post amplifier  78  and eeprom  80 , so a stiffener on the flexible cable  60  is not required. The receiver post amplifier  78  and eeprom  80  dies are wire bonded to the paddle card  74  to provide electrical connection and are encapsulated with molded potting compound to dissipate heat into a heat sink.  
         [0037]    [0037]FIGS. 3A &amp; 3B, in which like elements have like reference numbers, show isometric diagrams of a packaging architecture for a multiple array transceiver using a flexible cable made in accordance with the present invention.  
         [0038]    Referring to FIG. 3A, the optical lens assembly  84  is aligned and UV epoxy bonded to the forward vertical carrier  48 . Precise alignment provides efficient optical signal transfer. The heat sink  86  provides the 90-degree angle between the forward vertical carrier  48  and the I/O block  76 , as well as heat transfer from those elements. The paddle card  74  and forward vertical carrier  48  can be thermally connected to the heat sink  86  with adhesive, epoxy, or the like, as will be appreciated by those skilled in the art. The heat sink  86  can have fins, pins, vanes, passive cooling, or active cooling on the open surface to assist in heat transfer. The heat sink  86  can be made of any material with high thermal conductivity, such as aluminum or copper, and can be formed by various processes, such as die casting or machining.  
         [0039]    Referring to FIG. 3B, the heat sink  86  incorporates a heat sink vertical portion  90  and a heat sink horizontal portion  88 . The connection of the forward vertical carrier  48  and the paddle card  74  to the heat sink vertical portion  90  and a heat sink horizontal portion  88 , respectively, provides the 90-degree angle between the forward vertical carrier  48  and the I/O block  76 . This 90-degree configuration is required due to the right angle orientation between the customer&#39;s interior circuit board and the rear bulkhead of the chassis.  
         [0040]    The heat sink  86  further comprises an upper retainer shell  92  to house a fiberoptic connector (not shown). After the forward vertical carrier  48  has been assembled onto the heat sink  86 , a lower retainer shell  94  is attached to the upper retainer shell  92 . In one embodiment, the upper retainer shell  92  and lower retainer shell  94  can be connected with an interleaved mating feature, such as a dovetail joint or other slideable joint. In another embodiment, the lower retainer shell  94  can be attached to the upper retainer shell  92  with two screws, which also pass through the customer board at specified hole locations to structurally anchor the lower retainer shell  94  to the customer board. An EMI assembly clip (not shown) can be slid over the upper retainer shell  92  and the lower retainer shell  94 . The EMI assembly clip can provide both EMI and ground connection points to the customer chassis bulkhead.  
         [0041]    This completes the assembly of the multiple array transceiver module. The module can be attached to the customer&#39;s board by connecting the I/O block  76  to the mating connector on the customer&#39;s board, and securing four screws from the back side of the customer&#39;s board into mounting screw locations on the heat sink  86  and the lower retainer shell  94 . The module can be attached to the customer&#39;s board by reftow soldering the solder ball array  96  of the I/O block  76  to mating pad locations on the customer board.  
         [0042]    It is important to note that the figures and description illustrate specific applications and embodiments of the present invention, and is not intended to limit the scope of the present disclosure or claims to that which is presented therein. While the figures and description present a 2.5 gigahertz, 4 channel transmit and 4 channel receive multiple array transceiver, the present invention is not limited to that format, and is therefore applicable to other array formats including dedicated transceiver modules, dedicated receiver modules, and modules with different numbers of channels. For example, other embodiments can include multiple in-line lasers and receivers or arrays of lasers and receivers, e.g., 8×8 or 16×16 grids. Upon reading the specification and reviewing the drawings hereof, it will become immediately obvious to those skilled in the art that myriad other embodiments of the present invention are possible, and that such embodiments are contemplated and fall within the scope of the presently claimed invention.  
         [0043]    While the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.