The present application claims priority from Japanese patent application serial nos. 2005-146328, filed on May 19, 2005, and 2006-012094, filed on Jan. 20, 2006, the contents of which are hereby incorporated by reference into this application.
1. Field of the Invention
The present invention relates to a pluggable module and a cage, and particularly relates to a pluggable module and a cage in which production of metal powder due to insertion and drawing of the pluggable module is suppressed.
2. Description of Related Art
A plurality of venders of optical transceiver modules have designed and manufactured optical modules in the same specification under multi-source agreement (MSA). A specification of an optical transceiver module for 10 Gbits (XFP: 10 Gigabit Small Form Factor Pluggable) is described in “10 Gigabit Small Form Factor Pluggable Module” by SFF Committee. A structure of XFP is briefly described using
Flat springs 1a are welded to side faces of the cage 1. The flat springs are fitted with not-shown hole portions in side faces of the optical transceiver module 3 at a time point when the cage 1 is electrically connected to the optical transceiver module 3. As a result, the flat springs 1a latch the optical transceiver module 3. When the optical transceiver module 3 is drawn out, the flat springs are reset by a latch release mechanism (not shown) provided in the cage 1, and then the module is drawn out. When the optical transceiver module 3 is inserted and drawn with respect to the cage 1, the flat springs 1a slide on side faces of the optical transceiver module 3.
An aluminum heat sink 9 is attached to the upper opening of the cage 1 as shown in
While the cage, heat sink, and optical transceiver module 3 are integrally used, a user of the optical transceiver module 3 purchases each of them from different venders respectively. Moreover, the optical transceiver module is not exclusively inserted into the cage, and a transceiver module of an electric interface may be inserted. Such modules are called pluggable modules.
When an optical transceiver module with a metal case is inserted and drawn with respect to the cage, waste metal is produced in one of the flat springs, heat sink, and metal case due to metal-to-metal rubbing.
The waste metal produced in this way may cause short-circuit among electronic components mounted on the printed circuit board 2 or wiring lines depending on size of the waste metal. When a case of the optical transceiver module is formed of a nonconductive material such as plastic as a measure for this, a heat radiation effect is reduced.
A sliding portion of the module to the cage is formed of a member that is nonconductive and low in hardness compared with a member at a cage side. Alternatively, surface roughness of the portion that slides to the cage or the heat sink is designed to be 2.4 a or less.
As another measure, at least sliding surfaces of a pair of flat springs for grasping a pluggable module having a metal case in a cage, which holds the pluggable module and is mounted on a printed circuit board, are formed of a nonconductive material.
Moreover, a nonconductive material is used for contact surfaces of the cage which holds the pluggable module having the metal case and is mounted on the printed circuit board, and at least three faces of the nonconductive material cage are covered with a metal case.
Preferred embodiments of the present invention will now be described in conjunction with the accompanying drawings, in which:
Hereinafter, preferred embodiments of the invention will be described with reference to drawings. While the following embodiments are described in conjunction with an optical transceiver module, the embodiments of the invention can be applied to pluggable modules such as an electric transceiver module, optical transmitter module and optical receiver module.
Embodiment 1 is described using FIGS. 3 to 5. Here,
In
In the embodiment, since the flat spring 1a as metal and acryl as plastic slide to each other, a relatively weak acryl is necessarily scraped. However, since acryl is nonconductive, even if waste of the acryl is produced, short-circuit is not caused in a printed circuit board due to the waste.
While the acrylic sheets as nonconductive plastic were used in the embodiment, the sheets are not limited to these as long as they are nonconductive, and preferably those having hardness that is close to and lower than hardness of the flat spring. Resin having an excellent sliding property such as tetrafluoroethylene may be used.
According to the embodiment, the waste metal may not be produced while using metal having high heat radiation for a case material.
Here, a modification of the embodiment 1 is described using
According to the modification, the waste metal may not be produced while using the metal having high heat radiation for the case material as well.
Embodiment 2 is described using
In description of
The inventors conducted the following experiment under consideration that even if the waste metal is produced due to sliding to the heat sink, when surface roughness of the case of the optical transceiver module is small, the amount of the waste metal is decreased, and maximum length of the waste metal is reduced. In the experiment, three types of samples were used: a sample having surface roughness of 3.2 a (by Ra) of side faces of the case after casting, a sample having surface roughness of 2.4 a of the side faces of the case via surface polishing, and a sample having surface roughness of 1.6 a of the side faces of the case via surface polishing. In the experiment, the insertion and drawing were carried out 50 times with respect to the cage in a configuration of
In
Since the insertion and drawing are not actually performed so many times as 50 times, according to knowledge of the inventors, regarding production of the waste metal, when the side faces of the case are finished to have surface roughness of about 2.4 a (peak-to-peak of about 5 μm), the case can be used for XFP. More preferably, the surface roughness is about 1.6 a (peak-to-peak of about 3 μm).
Similarly, when a top of the case is finished to have surface roughness of about 2.4 a (peak-to-peak of about 5 μm), the case can be used for the optical transceiver module. More preferably, the surface roughness is about 1.6 a (peak-to-peak of about 3 μm). According to such surface processing, an air layer as a heat insulating layer between the optical transceiver module and the heat sink is reduced in thickness, and consequently improvement in heat radiation can be achieved.
The surface processing includes a chemical process such as surface treatment in addition to a mechanical process such as the surface polishing, however, they are not restrictive.
According to the embodiment, the amount of the waste metal can be significantly decreased while using the metal having high heat radiation for the case material. Moreover, heat radiation can be improved.
Embodiment 3 is described using
Coating of tetrafluoroethylene, which is engineering plastic having an excellent sliding property, on the flat springs allows the flat springs 1b to have both of spring and sliding properties.
In
PBT is engineering plastic having the spring property and excellent wear resistance. Therefore, if the flat springs lob slide to the optical transceiver module, the springs do not substantially wear, and even if they wear, only the nonconductive waste is produced. Here, the metal case 11 is grounded by the printed circuit board 2, and provides EMI shield for at least three faces of the cage 10. A contact portion of the cage 10 to the printed circuit board 2 is shielded by the printed circuit board 2. Here, a cage including the metal case is sometimes called cage.
According to the embodiment, at least a sliding portion of the cage to the optical transceiver module is made nonconductive, thereby production of the waste metal can be suppressed.
According to embodiments of the invention, waste metal produced due to sliding to the cage or the heat sink can be decreased.
Number | Date | Country | Kind |
---|---|---|---|
2005-146328 | May 2005 | JP | national |
2006-012094 | Jan 2006 | JP | national |