Patent Application
20050208797
Fiber optic transceivers are used in a variety of applications, including storage area networks (SANs), local area networks (LANs), Fibre Channel, Gigabit Ethernet, and synchronous optical network (SONET) applications. Fiber optic transceivers can be used as the network interface in mainframe computers, workstations, servers, and storage devices. Fiber optic transceivers can also be used in a broad range of network devices, such as bridges, routers, hubs, and local and wide area switches.
To promote the growth of the market for fiber optic transceivers, an industry standard has been developed based upon an agreement between several fiber optic transceiver manufacturers entitled “Cooperation Agreement for Small Form-factor Pluggable Transceivers”, as executed on Sep. 14, 2000 (herein “the Cooperation Agreement”), which is incorporated herein in its entirety. The Cooperation Agreement specifies the package outline, circuit board layout, and pin function definitions for small form factor transceivers. One of the standard small form factor transceivers specified includes ten input/output (I/O) pins. Up to ten pins are mounted on one side of the transceiver package and up to ten pins are mounted on the opposite side of the transceiver package. The pins are secured to a printed circuit board (PCB) within the transceiver housing and extend through the transceiver housing for coupling to a host.
Typically, two rows of at least five pins are manually soldered onto the printed circuit board for the I/O pins. The pins are typically edge clip pins or pin header assemblies soldered to the printed circuit board. The pins must be manually aligned and the soldering process typically requires several steps. The manual soldering process adds to the cost of manufacturing of the transceivers. Also, as a pin header is soldered to a PCB, wicking between pins in the header may occur causing solder to flow between pins. This can result in a short between pins.
In addition, many currently used I/O pins do not have sufficient rigidity resulting in the pins easily bending out of alignment. Bent pins can come into contact with the metallic housing of the transceiver and create electrical shorts possibly leading to failure of the transceiver.
One embodiment of the invention provides a pin header for a transceiver. The pin header for a transceiver comprises a frame comprising a rectangle that is indented on opposing sides of the rectangle, a first row of pins extending through the frame at a first angle to the rectangle, and a second row of pins extending through the frame at a second angle to the rectangle. The first row of pins is along a first side of the frame between the indented opposing sides and the second row of pins is along a second side of the frame between the indented opposing sides.
Embodiments of the invention are better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.
Mounting studs 40 and 42 are situated on opposite sides of transceiver 30. Mounting stud 40 is on one side of transceiver 30 and mounting stud 42 is on the other side of transceiver 30. Mounting studs 40 and 42 are used to mount transceiver 30 to a host. Pins 48 of pin header 38 are used to pass signals between transceiver 30 and the host. One row of five pins 48 extends through aperture 44 of housing 32 and the other row of fives pins 48 extends through aperture 46 of housing 32. Both rows of five pins 48 couple to the host. Housing 32 is made of metal, plastic, or another suitable material. In one embodiment, transceiver 30, and spacing of pins 48, conforms to the industry standard small from factor transceiver specifications.
Pins 48 are partially encased in frame 56 to maintain the alignment of pins 48. Frame 56 is rectangular with indented sides at 57a and 57b forming an hourglass shaped frame 56. Surface 56a of frame 56 is flat so pin header 38 can be handled by automated pick and place equipment. Automated pick and place equipment place pin header 38 on PCB 34 such that pins 48 are inserted into corresponding pre-plated through holes 52 of PCB 34. Pin header 38 is secured to PCB 34 by soldering pins 48 into the corresponding pre-plated through holes 52 of PCB 34. In one embodiment, a solder reflow process is used to solder pins 48 into pre-plated through holes 52.
Pogo-pin testing of PCB 34 can be performed after PCB 34 is installed in housing 32 as the hourglass shape of frame 56 allows a tester access to test point 50. In addition, the shape of frame 56 allows enough clearance such that components 54 can be mounted on PCB 34 underneath pin header 38.
Standoffs 60 support pin header 38 on PCB 34. Standoffs 60 prevent solder from flowing between pins 48 in each row of pins during the soldering process by leaving enough space, indicated at 64, around each pin 48 to prevent wicking between pins 48. Alignment studs 62 (only one alignment stud is visible in
Conical tips 63 of alignment studs 62 assist in the placement of pin header 38 on PCB 34 during manufacturing. Pick and place equipment place conical tips 63 into alignment stud holes 68 and release pin header 38. Pin header 38 falls into the correct position on PCB 34 as conical tips 63, and thus alignment studs 62 move to the center of alignment stud holes 68. This alignment process positions pins 48 in the desired location relative to PCB 34.
To place pin header 38 on PCB 34, a pick and place tool automatically positions pin header 38 such that pins 48 are started in holes 52. Alignment studs 62 align themselves with the corresponding alignment stud holes 68 of PCB 34 as pin header 38 is lowered into place. In addition, the pins 48 are aligned with the corresponding pre-plated through holes 52 of PCB 34.
Pins 48a-48j extend through frame 56 and include a shorter tail portion 100a and 100b extending up from frame 56, a captured portion 102a and 102b within frame 56, and a longer contact portion 104a and 104b extending down from frame 56. The tail portions 100a and 100b of pins 48a-48j are configured for mounting in pre-plated through holes 52 of PCB 34. The captured portions 102a and 102b of pins 48a-48j are enclosed within frame 56 to prevent movement of pins 48a-48j. In one embodiment, pins 48a-48j can withstand (remain in frame 56) up to a nine pound pull out force. The contact portions 104a of pins 48a-48e extend through aperture 46 of housing 32 and the contact portions 104b of pins 48f-48j extend through aperture 44 of housing 32. Pins 48a-48j are configured to electrically couple transceiver 30 to a host for transmitting signals between transceiver 30 and the host.
In one embodiment, pins 48a-48j are round and made of copper or brass and are plated with gold for greater electrical conductivity at solder joints and contacts. In one embodiment, the ends of pins 48a-48j are not plated while the rest of the pin is plated. Pins 48a-48j are rigid to resist bending and have a diameter within the range of 0.4 mm to 0.5 mm. The lengths of pins 48a-48j are similar and within the range of 8 mm to 11 mm. Both ends of pins 48a-48j are chamfered or rounded, such as at the ends 106 and 108 of pin 48f.
Frame 56 includes standoffs 60a and 60b and alignment studs 62a and 62b. Standoffs 60a and 60b support pin header 38 on PCB 34 and form voids 64 between and around pins 48a-48e and pins 48f-48j, respectively. Voids 64 prevent solder from flowing between pins 48a-48e and pins 48f-48j to prevent wicking during the soldering of pin header 38 to PCB 34.
Alignment stud 62a extends upward from the end of standoff 60a and alignment stud 62b extends upward from the end of standoff 60b. The conical tip 63a extends upward from alignment stud 62a and the conical tip 63b extends upward from alignment stud 62b. Conical tips 63a and 63b ease the alignment of alignment studs 62a and 62b into alignment stud holes 63 of PCB 34.
Frame 56 is comprised of a liquid crystal polymer that is injection molded around pins 48a-48j. In another embodiment, frame 56 is formed first and pins 48a-48j are post inserted into frame 56. Frame 56 extends around pins 48a-48j at captured portions 102a and 102b. In one embodiment, such as where pins 48a-48j are overmolded, frame 56 extends conically toward the ends of pins 48a-48j, such as at 110 of pin 48f. In another embodiment, such as where pins 48a-48j are post inserted into frame 56, conical portions, such as 110, are not included in frame 56.
Frame 56 has a rectangular shape with indentations at 57a and 57b to form an hourglass shape. Frame 56 includes a flat surface 56b opposite surface 56a (not visible in
Alignment stud 62a is positioned at an end of standoff 60a and alignment stud 62b is positioned at an end of standoff 62b. Alignment studs 62a and 62b are positioned at opposite corners 216 and 218 of frame 56. Alignment studs 62a and 62b are circular in shape and standoffs 60a and 60b are rectangular in shape with rounded ends.
Pin row 70 including pins 48a-48e is parallel to pin row 72 including pins 48f-48j. Pin 48a is directly opposite pin 48f, pin 48b is directly opposite pin 48g, pin 48c is directly opposite pin 48h, pin 48d is directly opposite pin 48i, and pin 48e is directly opposite pin 48j. Pins 48a-48e of row 70 are equally spaced and pins 48f-48j of row 72 are equally spaced. In one embodiment, the center pin to center pin spacing between pins 48a-48e and between pins 48f-48j is within the range of 1 mm to 2 mm.
Frame 56 includes the center portion 112, a tail capture portion 224, and a contact capture portion 226. Tail capture portion 224 includes conical portion 110 extending from frame 56 toward the end 108 of tail portion 100b and contact capture portion 226 includes conical portion 222 extending from frame 56 toward the end 106 of contact portion 104b. In another embodiment, conical portions 110 and 222 are not included in frame 56. Tail capture portion 224 extends above center portion 112 and contact capture portion 226 extends below center portion 112. In one embodiment, tail capture portion 224 is wider than contact capture portion 226.
Tail capture portion 224 maintains a space between center portion 112 and PCB 34 to allow other components to be mounted on PCB 34 above center portion 112. With pin header 38 installed in housing 32, contact capture portion 226 and conical portion 222 prevent pin 48f from contacting housing 32 and causing a short. The other pins 48 in pin header 38 are similarly configured to pin 48f.
