Patent Publication Number: US-2003228112-A1

Title: Solder mountable passive fiber optic components package

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to fiber optic components packages, and particularly to a solder mountable package assembly for securing passive fiber optic components to a printed circuit board (PCB).  
       [0003] 2. Related Art  
       [0004] Electro-optical devices are very commonly used in the modern fiber optics industry. Fiber optic components are often integrated with electronic circuits where a device having less volume is desired. Such devices include fiber optic components and electrical components on the same printed circuit board (PCB). Common examples include optical transceivers attached to a PCB, which have both electrical signal and fiber optic cable connectors. Sometimes, fiber optic passive components need to be integrated with electronic circuitry. There are two approaches to achieve this purpose. The first one is to combine a layer of fiber optic components with a layer of electronic circuitry, but this results in a large size package. The second way is to mount the fiber optic components on a PCB using screws or glue, with reference to FIG. 3. However, this requires extra space on the PCB for accommodating the screws, which is counter to the trend toward device miniaturization.  
       [0005] More importantly, soldering is often used when assembling electronic components to a PCB, while an additional procedure, possibly manual, is needed to assemble fiber optic passive components to the PCB using screws or glue, which is time-consuming and troublesome. This reduces productivity and increases cost. Also, neither of the above methods achieves the demands for compact size.  
       [0006] Accordingly, an improved package assembly for mounting passive fiber optic components to a PCB, and a method for making the same, is desired to overcome the above-mentioned problems.  
       SUMMARY OF THE INVENTION  
       [0007] An object of the present invention is to provide a solder mountable package assembly for passive fiber optic components that is easily integrated with a printed circuit board (PCB).  
       [0008] Another object of the present invention is to provide a package assembly for fiber optic passive components which occupies little space on a PCB.  
       [0009] To achieve the above objects, a solder mountable package assembly for securing fiber optic passive components to a PCB, according to the present invention, includes a housing, a passive fiber optic component accommodated in the housing, and a plurality of pins extending from a bottom of the housing. The pins are soldered at one end to the housing and are soldered at the other end to the PCB. Since the pins extend downwardly from the bottom of the housing, the package assembly occupies approximately an area on the PCB of the housing bottom. Thus the design saves space. Moreover, since surface mounting technology (SMT) or another soldering technology is used to fix all the electronic elements and the fiber optic components to the PCB, no extra procedures using glue or screws, or other manual procedures, is required. The efficiency of assembling is improved.  
       [0010] These and additional objects, features and advantages of the present invention will become more apparent after reading the following detailed description of a preferred embodiment of the invention when taken in conjunction with the appended drawings, in which: 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 is a perspective view of a solder mountable fiber optic components package according to the present invention;  
     [0012]FIG. 2 is a schematic view of the solder mountable fiber optic components package of FIG. 1 mounted to a printed circuit board (PCB); and  
     [0013]FIG. 3 is a perspective view of a fiber optic components package of the prior art. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0014] Those of ordinary skill in the art will realize that the following description of the present invention is illustrative only and not in any way limiting. Other embodiments of the invention will readily suggest themselves to such skilled persons having the benefit of this disclosure. Like reference numerals are used throughout to refer to like elements.  
     [0015] Turning now to FIG. 1 and FIG. 2, a solder mountable package assembly  1  for securing a passive fiber optic component  12  to a printed circuit board (PCB)  3  comprises a package  10 , the passive fiber optic component  12  received in the package  10 , and a plurality of pins  11  made of metal material. The passive fiber optic component  12  shown as an example in FIG. 1 is a wavelength divisional multiplexer (WDM), which has optical fibers (not labeled) located therein. The package  10  comprises a housing  102  made of metal for accommodating the fiber optic component  12  therein, two caps  104 , and a pair of rubber boots  106  used to protect the optical fibers entering the housing  102 . The housing  102  has two openings at opposite ends for passage of the fiber optic component  12  during assembly and for passage of the optical fibers when assembled. The caps  104  are used to cover the openings to encapsulate the fiber optic component  12  completely. The pins  11  extend downwardly from a bottom (not labeled) of the housing  102 , and can be attached to the housing  12  using point soldering or other well-known techniques. The housing  102  can alternatively be made of a plastic material.  
     [0016] A process of assembling the package assembly  1  includes the followings steps: (1) providing the housing  102  having two openings at opposite ends; (2) attaching a plurality of pins  11  to the bottom of the housing  102  by point soldering; (3) inserting the passive fiber optic component  12  through one of the two openings into the housing  102 ; (4) covering the openings with corresponding caps  104  and fixing boots  106  to the caps  104  to encapsulate the fiber optic component  12  completely; and (5) inserting the pins  11  through through holes (not shown) in the PCB  3  and soldering the pins  11  to the through holes in the PCB  3 . Since the pins extend downwardly from the bottom of the housing  102 , the package assembly  1  takes up only the space on the PCB  3  of an area of the bottom of the housing  102  and a bottom surface of the two caps  104 , saving space on the PCB  3 . Thus, this design saves space on the PCB  3  and promotes miniaturization of components on a PCB. Moreover, since surface mounting technology (SMT) or another soldering technology is used to fix all the electronic elements and the fiber optic components to the PCB  3 , no extra procedures using glue or screws, or other manual procedures, is required to assemble such fiber optic components on the PCB  3 . The efficiency of assembling is thereby greatly improved.  
     [0017] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.