KR100720789B1 - Optical transmission/receiving module for bi-directional communication improved in heat-dissipating structure - Google Patents

Abstract

The present invention relates to a bidirectional optical transmission and reception module with improved heat dissipation structure.

According to the present invention, an optical waveguide is formed on a flat substrate, and an optical fiber is disposed on one side so as to be aligned with the optical waveguide, a wavelength separator interposed in the optical waveguide, and an optical waveguide branched by using the wavelength separator as a branch point. A PLC device having a light emitting device and a light receiving device coupled thereto; A printed circuit board on which the PLC device is mounted and electrically connected to the light emitting device and the light receiving device; A metal case packaging the PLC device and a printed circuit board; And a heat sink interposed between the flat substrate surface of the PLC device or the surface of the printed circuit board, or between the surfaces of both substrates and the inner wall of the metal case.

PLC, PCB, Heat Sink, Beer Hole, WDM Filter, TO-CAN

Description

Bidirectional optical transmission module with improved heat dissipation structure {OPTICAL TRANSMISSION / RECEIVING MODULE FOR BI-DIRECTIONAL COMMUNICATION IMPROVED IN HEAT-DISSIPATING STRUCTURE}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to

1 is a side view showing the configuration of a bidirectional optical transmission module according to the prior art.

2 is a graph showing the light output characteristics of the bidirectional optical transmission and reception module according to the prior art.

Figure 3 is a side view showing the configuration of a bidirectional optical transmission and reception module according to a preferred embodiment of the present invention.

4 is a plan view illustrating the configuration of the PLC device of FIG. 3.

5 is a graph showing the light output characteristics of the bi-directional optical transmission and reception module according to an embodiment of the present invention.

<Description of main reference numerals in the drawings>

100 ... PLC element 101 ... plane

102 ... optical waveguide 103 ... V groove

104 ... optical fiber 105 ... light emitting element

106 ... Receiver 108 ... Wavelength Separator

Printed Circuit Board 110 Ceramic Board

111 Metal case 112 Heat sink

113.Beer hole 114.Metal pad

115.Adhesive member 116.Uneven structure

The present invention relates to a bi-directional optical transmission module, and more particularly, to a bi-directional optical transmission module having a heat dissipation structure that can improve the emission efficiency for the heat generated during operation of the light emitting and receiving elements for transmitting and receiving optical signals will be.

In order to construct an optical subscriber network, a bidirectional optical transmission / reception module for converting an electrical signal into an optical signal in an arbitrary wavelength band and transmitting the optical signal to the optical fiber, and detecting an optical signal in an arbitrary wavelength band received through the optical fiber and inverting it into an electrical signal, is essential. Is required.

In general, the optical transmission / reception module includes a laser diode (LD) that generates an optical signal corresponding to the electrical signal, and a photodiode (PD) that detects the optical signal received through the optical fiber and inverts the electrical signal into an electrical signal. It is configured to be combined with an optical fiber which is an optical signal transmission medium through Planar Lightwave Circuit (PLC) technology.

The PLC device used in the bidirectional optical transmission / reception module includes a laser diode and a photodiode for receiving spaced apart from each other spatially on a flat substrate on which an optical waveguide is formed, and a wavelength separator for separating optical signals transmitted and received through an optical fiber; A monitor photodiode for monitoring the operation of the laser diode is disposed.

In the bidirectional optical transmission / reception module, as shown in FIG. 1, an optical fiber 11, which is an optical transmission medium, is disposed on a flat substrate of the PLC element 10, and the PLC element 10 is connected to a printed circuit board through a ceramic substrate 12. PCB (13) is mounted on, and finally packaged in a plastic case (14) for the protection of optical and electronic components.

On the other hand, as with other electronic components, some of the current applied to the laser diode is converted to heat. Due to the characteristics of the semiconductor device, the laser diode has a higher conversion rate to heat as the operating environment is a high temperature environment, thereby intensifying the degree of deterioration of the light output characteristic. Therefore, in the conventional optical transmission / reception module, when the current I _M of the monitor photodiode is measured while varying the driving current I _D applied to the laser diode, the optical transmit / receive module becomes light as the temperature increases. The output becomes smaller.

The present invention has been made in consideration of the above, and has a structure that can lower the thermal resistance so that the heat generated during operation of the device for transmitting and receiving the optical signal is smoothly discharged from the PLC device or the printed circuit board to the outside of the case The purpose is to provide a bidirectional optical transmission module.

In order to achieve the above object, the bidirectional optical transmission / reception module according to the present invention uses a metal case having a relatively excellent heat dissipation efficiency to package a PLC device and a printed circuit board, and to generate heat generated from an optical device mounted on the PLC device. It has a structure in which a heat sink is arranged to smoothly absorb heat and transfer it to the metal case.

That is, in the bidirectional optical transmission module according to the preferred embodiment of the present invention, an optical waveguide is formed on a flat substrate, and an optical fiber is disposed on one side so as to be aligned with the optical waveguide, and a wavelength separator interposed in the optical waveguide and the wavelength separator. A PLC device having a light emitting element and a light receiving element which are optically coupled to an optical waveguide branched at a branch point; A printed circuit board on which the PLC device is mounted and electrically connected to the light emitting device and the light receiving device; A metal case packaging the PLC device and a printed circuit board; And a heat sink interposed between the flat substrate surface of the PLC device or the surface of the printed circuit board, or between the surfaces of both substrates and the inner wall of the metal case.

A laser diode is used as the light emitting element, and a photo diode is preferably used as the light receiving element.

In addition, a photodiode for a monitor for monitoring the light output of the laser diode may be further disposed near the laser diode.

Preferably, a ceramic substrate may be interposed between the PLC device and the printed circuit board.

Preferably, a metal pad and an adhesive member may be interposed between the heat sink and the surface of the substrate to which the heat sink is attached.

It is preferable that a thermal epoxy or a thermal pad is used as the adhesive member.

In addition, a plurality of via holes may be formed on the surface of the printed circuit board.

In addition, the heat sink includes a concave-convex structure, it is preferable that a plurality of through-holes are formed in the metal case to facilitate the flow of air between the inside / outside.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

Figure 3 is a side view showing the configuration of a bidirectional optical transmission and reception module according to a preferred embodiment of the present invention.

Referring to FIG. 3, a bidirectional optical transmission / reception module according to an exemplary embodiment of the present invention includes a PLC device 100 capable of transmitting and receiving an optical signal and a printed circuit board 109 mounted below the PLC device 100. And a heat interposed between the metal case 111 for packaging the PLC element 100 and the printed circuit board 109 and the inner wall of the PLC element 100 and / or the printed circuit board 109 and the metal case 111. Heatsink 112.

As shown in more detail in FIG. 4, in the PLC device 100, an optical waveguide 102 is formed in a predetermined pattern on the planar substrate 101, and a V-shaped groove is formed on one side of the planar substrate 101. 103 is formed so that the optical fiber 104 corresponding to the optical transmission medium is arranged while being aligned with the optical waveguide 102.

In the PLC device 100, the light emitting device 105 and the light receiving device 106 are spaced apart from each other and are mounted. The laser diode LD is used as the light emitting device 105, and the photodiode PD is preferably used as the light receiving device 106. However, various equivalents may be used.

Additionally, a monitor photodiode 107 is mounted near the light emitting device 105 to monitor the light output of the light emitting device 105.

For bidirectional transmission and reception of the optical signal through the optical fiber 104, the optical waveguide 102 is interposed with a wavelength separator 108 for separating the wavelength of the transmitted light and the wavelength of the received light. For example, a wavelength division multiplexing (WDM) filter may be employed as the wavelength separator 108.

The light emitting device 105 and the light receiving device 106 are optically coupled to the optical waveguide 102 branched using the wavelength separator 108 as a branch point. Here, the wavelength separator 108 filters the transmitted light emitted from the light emitting device 105 to proceed to the optical fiber 104, while filtering the received light coming through the optical fiber 104 to the light receiving device 106. .

The PLC device 100 is mounted on a printed circuit board 109 on which components for electric driving and electric signal input / output of the light emitting device 105, the light receiving device 106, and the like are mounted. At this time, it is preferable that the ceramic substrate 110 is interposed between the printed circuit board 109 and the PLC device 100 to increase the heat transfer efficiency.

The printed circuit board 109 and the PLC device 100 mounted thereon are collectively packaged by a protective metal case 111, where the printed circuit board 109 and / or the PLC device 100 are heatsinks 112. It is connected to the metal case 111 via).

The heat sink 112 is interposed between the surface of the planar substrate 101 of the PLC device 100 or the surface of the printed circuit board 109, or between the surfaces of both substrates and the inner wall of the metal case 111. The heat generated from the 100 is dissipated into the air and transferred to the metal case 111 at the same time.

Here, it is preferable that a plurality of through holes 111a are formed at one side of the metal case 111 so as to smoothly flow air between the inside and the outside of the case. In addition, the heat sink 112 preferably includes an uneven structure 116 to increase the contact area with air.

In order to fix the PLC device 100 and / or the printed circuit board 109 and the heat sink 112, a metal pad 114 and an adhesive member 115 are sequentially provided on the surface of the substrate, and the adhesive member 110 is provided. Through the heat sink 112 is attached. Here, the metal pad 114 serves to enhance heat dissipation characteristics and adhesion, and also provides a function of blocking crosstalk noise when connected to the ground of the printed circuit board 109.

As the adhesive member 115, it is preferable to employ a thermal epoxy or a thermal pad. In particular, the thermal pad may also provide an effect of filling and cushioning the gap between the surface of the substrate and the heat sink 112 or the heat sink 112 and the metal case 111.

In order to increase the heat radiation efficiency from the printed circuit board 109 to the heat sink 112, a plurality of via holes 113 may be formed on the surface of the printed circuit board 109. When the via hole 113 is formed, the surface area of the printed circuit board 109 that emits heat to the metal pad 114 may be increased, thereby improving heat dissipation efficiency.

As described above, the bidirectional optical transmission / reception module according to the preferred embodiment of the present invention is a PLC device 100 / printed circuit board when heat is generated as the light emitting device 105 and the light receiving device 106 operate to transmit and receive an optical signal. 109, the heat sink 112, and the metal case 111 are transferred in order to radiate heat with high efficiency.

Here, the via hole 108 is formed on the surface of the printed circuit board 109 to which the heat sink 112 is attached, so that the heat dissipation area is increased, and a plurality of through holes 113 are formed in the metal case 111 to form the metal case ( 111) Since the air flows smoothly between the inside and the outside, it provides improved heat dissipation characteristics.

5 is a view illustrating light output characteristics of the bidirectional optical transmission / reception module according to the preferred embodiment of the present invention.

Referring to FIG. 5 together with FIG. 2, for example, in an operating temperature environment of 85 ° C., a heat dissipation structure such as a heat sink 112 and a metal case 111 when comparing the conventional technology and the light output characteristics of the present invention. It can be seen that the case of the present invention having the optical power characteristic is not only high, but also close to the optical power characteristic of the laser diode packaged in the TO-CAN type.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

According to the present invention, the heat resistance of the heat dissipation path from the PLC element and the printed circuit board to the case is reduced, thereby minimizing deterioration of light output characteristics at high temperatures.

In addition, according to the present invention, the via hole for increasing the heat dissipation area is formed in the printed circuit board, the case is made of a metal material and the through hole for the circulation of air can be further improved heat dissipation efficiency.

In addition, since a metal pad and a heat pad are interposed between the surface of the PLC element and the printed circuit board and the heat sink, heat dissipation characteristics are improved and the substrate can be stably buffered with respect to the metal case.

Claims (9)

An optical waveguide is formed on a flat substrate, and an optical fiber is disposed on one side so as to be aligned with the optical waveguide, and a light emitting device optically coupled to a wavelength separator interposed in the optical waveguide, and an optical waveguide branched using the wavelength separator as a branch point. PLC element having a light receiving element; A printed circuit board on which the PLC device is mounted and electrically connected to the light emitting device and the light receiving device; A metal case packaging the PLC device and a printed circuit board; And And a heat sink interposed between the flat substrate surface of the PLC device or the surface of the printed circuit board, or between the surfaces of both substrates and the inner wall of the metal case. The method of claim 1, A laser diode is employed as the light emitting element, A photodiode is adopted as the light receiving element. The method of claim 2, And a monitor photodiode installed near the laser diode to monitor the light output of the laser diode. The method according to claim 1 or 2, And a ceramic substrate interposed between the PLC element and the printed circuit board. The method according to claim 1 or 2, And a metal pad and an adhesive member interposed between the heat sink and a surface of the substrate to which the heat sink is attached. The method of claim 5, The adhesive member is a bi-directional optical transmission module, characterized in that the thermal epoxy or heat pad is employed. The method of claim 5, Bi-directional optical transmission and reception module, characterized in that a plurality of via holes are formed on the surface of the printed circuit board. The method of claim 5, Bidirectional optical transmission and reception module, characterized in that the heat sink includes an uneven structure. The method of claim 1, The metal case bidirectional optical transmission module, characterized in that a plurality of through-holes are formed to facilitate the flow of air between the inside / outside.

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