WO2019132076A1

WO2019132076A1 - Optical module having excellent thermal characteristics

Info

Publication number: WO2019132076A1
Application number: PCT/KR2017/015740
Authority: WO
Inventors: 정새한솔; 이상수; 송재호
Original assignee: 주식회사 옵텔라
Priority date: 2017-12-28
Filing date: 2017-12-29
Publication date: 2019-07-04
Also published as: KR20190080238A; KR102031651B1

Abstract

The present invention relates to an optical module and, more specifically, to an optical module having excellent thermal characteristics, wherein a heat-blocking means for blocking heat is formed in a substrate between an optical element and an IC, thereby preventing, in advance, a thermal noise which the heat generated in the IC may apply to the optical element. The present invention provides an optical module comprising: a substrate; an IC installed on the substrate; a submount formed on the substrate to protrude therefrom; an optical element installed on the submount and configured to output or receive an optical signal; a block installed on the substrate and having an optical waveguide formed therein; and a connection means electrically connecting the optical element and the IC, wherein a heat-blocking means for blocking heat is formed in the substrate between the optical element and the IC.

Description

Optical module with excellent thermal characteristics

The present invention relates to an optical module, and more particularly, to an optical module, in which a heat terminal unit for interrupting heat is provided on a substrate between an optical element and an IC to prevent heat generated in the IC from being transmitted to the optical device, And more particularly to an optical module having excellent thermal characteristics that can prevent the optical module from being damaged.

With the rapid increase of smartphone penetration rate, large capacity contents based communication service has been requested and accordingly, a method of increasing the data traffic capacity has been researched steadily. In order to achieve compatibility between these research and development achievements, the International Organization for Standardization (IETF) has published standards for the same wavelength multi-channel technology and wavelength division multiplexing technology, and many organizations and researchers are studying the practical application of technologies according to this standard .

These technologies are being developed for the purpose of low cost, high speed, miniaturization and low power consumption. For this purpose, a laser array based optical module has been developed as a component of a network and is used in actual application fields.

An example of such an optical module is disclosed in U.S. Published Patent Application No. 2016-0349451 (hereinafter referred to as "Prior Art Document 1").

4 is a cross-sectional view of a conventional optical module disclosed in the prior art document 1.

4, a conventional optical module disclosed in the prior art document 1 includes a printed circuit board 600, a mount 100 formed on the printed circuit board 600, An arrayed waveguide grating (AWG) 200 for applying light to the plurality of photodetectors 310 and a plurality of photodetectors 310 provided in the photodetector 310, And a driver 700 for transmitting the electric signal. The light incident through the AWG 200 is refracted by the end slope 240 of the waveguide 230 and is detected by the photodetector 310. The light detected by the photodetector 310 is converted into an electric signal and transmitted to the driver 700 through the bonding wire M. The optical module 10 is a photodetector for receiving light, and it may be a laser diode or the like which emits light if necessary.

The AWG 200 is mounted on the upper surface of the mount 100 and fixed to the AWG 200 by using a bonding pad 110. The AWG 200 is mounted on the upper side of the optical detector 310, Respectively.

However, when the conventional optical module disclosed in the prior art document 1 is a light emitting device rather than a photodetector, the heat generated in the IC is transmitted to the light emitting device through the printed circuit board and the mount to limit the operating temperature of the light emitting device, .

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an optical module having excellent thermal characteristics to block heat so that heat generated in an IC is transmitted to an optical device to prevent thermal noise.

The present invention relates to a semiconductor device, which comprises a substrate, an IC provided on the substrate, a submount formed to protrude on the substrate, an optical element for outputting or receiving an optical signal provided on the submount, There is provided an optical module including a block in which an optical waveguide is formed and a connecting means for electrically connecting the optical device and the IC, wherein a heat terminal means for interrupting heat is formed in the substrate between the optical device and the IC .

Wherein the heat terminal means is a trench formed in the substrate between the optical element and the IC.

In addition, it is preferable that the heat block means is a partition wall formed on the substrate between the optical element and the IC.

In addition, it is preferable that the heat spread is separately formed in the lower part of the optical element and the substrate under the IC.

The heat spread is preferably a flexible graphite sheet.

It is also preferable that the trench is filled with a thermal barrier material.

It is preferable that the difference in thermal expansion coefficient between the thermal barrier material and the material constituting the substrate is less than 5%.

Also, the heat shielding material is preferably a nanofiber web having a plurality of pores by electrospinning a polymer material.

The nanofiber may further include a heat insulating filler.

In addition, the heat insulating filler as _{_{SiO 2, SiON, Si 3 N}} 4, HfO 2, ZrO 2, Al 2 O 3, TiO 2, Ta 2 O 5, MgO, Y 2 O 3, BaTiO 3, ZrSiO 4, HfO 2 , Or one or more particles selected from the group consisting of glass fibers, graphite, rock wool, and clay.

As described above, the optical module according to the present invention is provided with the heat-shielding means for shielding heat from the substrate between the optical element and the IC, so that thermal noise is improved and thermal noise can be prevented.

In the optical module according to the present invention, since the heat generated by the IC is prevented from being transferred to the optical element by forming the trench by the heat-conducting end means, the thermal noise of the optical element can be more easily prevented.

In addition, since the optical module according to the present invention is formed with the partition wall by the heat block means and is discharged to the atmosphere through the upper end of the partition wall, the heat generated by the IC is prevented from being transferred to the optical device, so that the thermal noise can be prevented more easily.

In the optical module according to the present invention, the heat spread is separately formed in the lower part of the optical device and the substrate under the IC, so that the heat generated in the optical device can be easily released to the outside.

In the optical module according to the present invention, since the heat spread is separately formed in the bottom of the IC and the substrate under the optical element, a path for emitting heat generated in the IC and a path for emitting heat generated in the optical element are separated The influence of the heat generated in the IC on the optical device can be effectively reduced.

In addition, the optical module according to the present invention can form a thermal via having a good thermal conductivity on the substrate under the IC and under the optical element, and can efficiently transmit the heat generated from each device to the respective heat spreads.

Further, since the optical module according to the present invention has the flexible graphite sheet as the heat spread, the thermal conductivity in the plane direction is excellent, and hot spots can be prevented from being generated.

In the optical module according to the present invention, since the trenches are filled with the thermal material, the heat generated in the IC is transferred to the optical device, thereby preventing the occurrence of the operation temperature limitation and the thermal noise.

In addition, since the optical module according to the present invention has a thermal differential material such that the difference in thermal expansion coefficient between the material constituting the substrate and the thermal expansion coefficient is less than 5%, the substrate can be prevented from being twisted by the heat shield material.

Further, since the optical module according to the present invention further includes a heat insulating filler for blocking heat transfer to the nanofiber, the optical module is provided in the form of a nanofiber web having a plurality of pores by electrospinning a polymer material with the thermal conductive material, It is possible to more reliably prevent the heat from being transmitted to the optical element.

1 is a cross-sectional view showing a first embodiment of an optical module according to the present invention.

2 is a cross-sectional view showing a second embodiment of the optical module according to the present invention.

3 is a cross-sectional view showing a third embodiment of the optical module according to the present invention.

Hereinafter, embodiments of the optical module according to the present invention will be described with reference to the accompanying drawings.

[First Embodiment]

1, the optical module 10 includes a substrate 12, an IC 13 mounted on the substrate 12, a submount 14 formed to protrude on the substrate 12, An optical element 15 for outputting or receiving an optical signal provided on the submount 14, a block 17 provided on the substrate 12 and provided with an optical waveguide 16, (15) and the IC (13).

The substrate 12 is preferably a PCB or FPCB capable of an electrical interface and is made of a material having a high thermal conductivity to smoothly discharge heat generated in the IC 13 to the outside. Therefore, the substrate 12 can be made of various materials having excellent thermal conductivity and being an insulating material, and can be made of materials such as silicon, silicon compounds such as Si, SiO, and SiO ₂ , ceramics such as Al ₂ O ₃ and AlN, . In addition, a thermal via (not shown) is formed at the lower end of the IC 13 and the optical element 15 placed on the substrate 12, so that the heat generated in each device can be more effectively radiated to the outside. In addition, thermal vias (not shown) are formed at the lower end of the IC 13 and the optical device 15 located on the upper side of the substrate 12 so that the heat generated from each device can be more effectively radiated to the outside. In this embodiment, the substrate 12 includes a base layer 12a and

cover layers

12b and 12c protruding upward from both sides of the base layer 12a. The block 17 is fixed to the cover layer 12c on one side of the

cover layers

12b and 12c.

The IC 13 is provided to supply power to the optical device 15 or to transmit an electric signal generated by the optical device 15 to a control unit (not shown). Here, the IC 13 is installed to be supported by the base layer 12a of the substrate.

The submount 14 is formed to protrude on the substrate 12, and an optical element 15 is mounted on the substrate 12. The submount 14 may be attached to the substrate 12 or may be formed integrally with the substrate 12 as required. Here, the submount 14 is set to a height in consideration of the gap between the optical element 15 provided on the top and the tip of the optical waveguide 16 formed on the block 17.

The optical element 15 is installed on the submount 14 to output or receive an optical signal. When the optical element 15 is provided as a light source for outputting an optical signal, it may be a VCSEL or a laser diode for transmitting a laser used for optical communication. In addition, when the optical device 15 is a light receiving device for receiving an optical signal, the optical device is provided as a photodetector and the optical signal is transmitted in a direction opposite to that in the case where the optical device 15 is a light source. A bonding wire 18 is provided to electrically connect the optical element 15 and the IC 13 to each other.

The block 17 is made of a glass material and is transparent. Needless to say, other materials can be used as needed. The block 17 is installed on one side cover layer 12c of the substrate 12. [ In the block 17, an optical waveguide 16 is formed. The optical waveguide 16 may be an optical fiber 16 as required.

The optical waveguide 16 formed in the block 17 extends parallel to the substrate 12 and has a tip end reaching directly above the optical device 15. [ In this embodiment, the front surface of the block 17 is cut along with the tip of the optical waveguide 16, and the total reflection is performed through the cut surface 16a to refract light. In the present embodiment, the cut surface 16a is a VCSEL and is provided at 41 degrees in consideration of reflection. However, it is needless to say that it can be cut at various angles such as 45 degrees according to need.

The heat terminal means is formed on the substrate 12 between the optical element 15 and the IC 13 to block the heat generated in the IC 13 from being transmitted to the optical element 15. [

Specifically, the trench 19a and the separating wall 19b are formed by the heat block means.

Here, the trench 19a is formed in a square shape on the optical device side of the IC 13. The trench 19a may have a portion penetrating through the substrate 12 in the thickness direction, if necessary.

The trench 19a is filled with the thermal conductive material to improve the structural stability and further reliably prevent the heat generated in the IC 13 from being transmitted to the optical device 15 side. In order to prevent deformation of the substrate 12, it is preferable that the difference in thermal expansion coefficient between the material forming the substrate 12 and the substrate 12 is less than 5%.

In the present embodiment, the thermal conductive material is provided in the form of a nanofiber web having a plurality of pores by electrospinning a polymer material. As the diameter of the nanofibers is smaller, the specific surface area of the nanofibrous web is increased and the heat collecting ability of the nanofibrous web having a plurality of micropores is increased, thereby improving the heat insulating performance. Therefore, when the diameter of the nanofiber is 0.1um or less, the nanofiber property is degraded. When the diameter is more than 1.5um, the pore size becomes large and the heat trapping ability is low.

In this embodiment, the method of spinning the nanofibers may be performed by conventional electrospinning, air-electrospinning (AES), electrospray, electrobrown spinning, centrifugal electrospinning, , And flash-electrospinning may be used.

Here, the nanofibers may further include a heat insulating filler to improve the strength. The heat insulating filler is made of _{_{SiO 2, SiON, Si 3 N}} 4, HfO 2, ZrO 2, Al 2 O 3, TiO 2, Ta 2 O 5, MgO, Y 2 O 3, BaTiO 3, ZrSiO 4, HfO 2 And at least one particle selected from the group consisting of glass fibers, graphite, rock wool, and clay.

And heat spreads 11a and 11b for separating heat generated in the optical element 15 and heat generated in the IC 13 from the outside of the optical element 15 and the substrate 12 under the

IC

13, 11b are separately formed. The heat spreads 11a and 11b are preferably formed of a flexible graphite sheet.

The flexible graphite sheet may comprise compressed particles of exfoliated graphite. The scraped flexible graphite sheet may have a thickness of about 0.010 mm to 3.75 mm and a typical density of about 1.0 to 2.0 g / cc or greater. In this embodiment, the flexible graphite sheet is commercially available as eGRAF® material from GrafTech International Holdings Inc., Independence, Ohio, USA.

[Second Embodiment]

2, the optical module 20 includes a substrate 22, an IC 23 mounted on the substrate 22, a submount 24 formed to protrude on the substrate 22, An optical element 25 for outputting or receiving an optical signal provided on the submount 24 and a bonding wire 28 for electrically connecting the optical element 25 and the IC 23 to each other, And a block 27 formed on the substrate 22 and having an optical waveguide 26 formed thereon, and a train 27 formed to block heat on the substrate 12 between the optical device 25 and the IC 23. [ End means.

In this embodiment, the substrate 22, the IC 23, the submount 24, and the optical device 25 are similar to those of the first embodiment, and a detailed description thereof will be omitted and the characteristic configuration of the present embodiment will be mainly described .

The block 27 is provided on the cover layers 22b and 22c on both sides of the substrate 22 made up of the base layer 22a and the cover layers 22b and 22c protruding upward on both sides of the base layer 22a. And an optical waveguide 26 for guiding light is formed. The block 27 is made of a glass material and is transparent. Needless to say, it is of course possible to use a block 27 of a different material as necessary.

The optical waveguide 16 formed on the block 27 extends vertically to the substrate 22 and has a tip end reaching directly above the optical element 25. In the present embodiment, when the optical element 25 is a VCSEL, light emitted from the VCSEL is directly transmitted to the outside through the optical waveguide. When the optical device 25 is a photodetector, light applied through the optical waveguide 26 is directly incident on the optical device 25 and receives the optical signal.

The heat terminal means is formed on the substrate 22 between the optical element 25 and the IC 23 to block the heat generated in the IC 23 from being transmitted to the optical element 15. [

Specifically, the trench 29a and the separating wall 29b are formed by the heat insulating means.

Here, the trench 29a is formed in a square shape on the optical device side of the IC 23. The trench 29a may have a portion penetrating through the substrate 22 in the thickness direction, if necessary.

The trench 29a is filled with the thermal conductive material to improve the structural stability and further reliably prevent the heat generated in the IC 23 from being transmitted to the optical device 25 side.

The heat spreads 21a and 21b for separating heat generated in the optical element 25 and heat generated in the IC 23 from the outside of the optical element 25 and the substrate 22 under the

IC

23, 21b are separately formed. The heat spreads 21a and 21b are preferably formed of a flexible graphite sheet.

The composition of the thermal barrier material and the material forming the heat spread is similar to that of the first embodiment, and thus a detailed description thereof will be omitted.

[Third Embodiment]

3, the optical module 30 according to the present embodiment includes a substrate 32, an IC 33 mounted on the substrate 32, a sub- An optical device 35 for outputting or receiving an optical signal provided on the submount 34; a block 37 having an optical waveguide 36 formed on the substrate 32; (32) between the IC (35) and the IC (33).

The substrate 32 includes a base layer 32a and a cover layer 32b protruding upward from one side of the base layer 32a. The block 37 is closely attached to the side surface of the cover layer 32.

The IC 33 is provided to supply power to the optical device 35 or to transmit an electrical signal generated by the optical device 35 to a control unit (not shown). Here, the IC 33 is installed to be supported by the base layer 12a of the substrate.

The submount 34 is formed to protrude on the substrate 32, and an optical element 35 is mounted on the substrate 32. The submount 34 may be attached to the substrate 32 or may be integrally formed with the substrate 32 as required. The height of the submount 34 is set so that the center of the optical waveguide 36 coincides with the center where the light of the optical device 35 enters or exits.

The optical element 35 is installed on the submount 34 to output or receive an optical signal. When the optical element 35 is provided as a light source for outputting an optical signal, it may be a laser diode that emits light used for optical communication to the side. When the optical element 35 is a light receiving element for receiving an optical signal, the optical detector is provided as a photodetector and the optical signal is transmitted in a direction opposite to that when the optical element 35 is a light source. A bonding wire 38 is provided to electrically connect the optical element 35 and the IC 33 to each other.

The block 37 is closely attached to the submount 34 on the substrate 32 and has an optical waveguide 36 formed thereon. The block 37 is made of a glass material and is transparent. Needless to say, it is of course possible to use the block 37 of a different material according to need. The optical waveguide 36 formed in the block 37 extends parallel to the substrate 32 and has a tip end reaching a side surface of the optical device 35. The optical waveguide 36 formed in the block 37 extends parallel to the substrate 32 and has a tip end reaching the side surface of the optical element 35. In this embodiment, In this embodiment, the optical device 35 may be a laser diode that emits light to the side. When the optical device 35 is a photodetector, light applied through the optical waveguide 36 is directly incident on the optical device to receive the optical signal.

The heat terminal means is formed on the substrate 32 between the optical element 35 and the IC 33 to block the heat generated in the IC 33 from being transmitted to the optical element 35.

Specifically, the trench 39a and the separating wall 39b are formed by the heat insulating means.

Here, the trench 39a is formed in a square shape on the optical device side of the IC 33. The trench 39a may have a portion penetrating the substrate 32 in the thickness direction, if necessary. The trench 19a is filled with the thermal conductive material to improve the structural stability and further reliably prevent the heat generated in the IC 13 from being transmitted to the optical device 15 side.

And heat spreads 31a and 31b for separating the heat generated in the optical device 35 and the heat generated in the IC 33 from the outside of the optical device 35 and the substrate 32 under the

IC

33, 31b are separately formed. The heat spreads 31a and 31b are preferably formed of a flexible graphite sheet.

[Description of Symbols]

10, 20, 30: optical module

11a, 11b, 21a, 21b, 31a, 31b: heat spread

12, 22, 32: substrate

13, 23, 33: IC

14, 24, 34: Submount

15, 25, 35: optical element

16, 26, 36: optical waveguide

17, 27, 37: block

18, 28, 38: bonding wire

12a, 22a, 32a: a base layer

12b, 12c, 22b, 22c, and 32b:

19a, 29a, 39a: trenches

19b, 29b, 39b:

Claims

An optical module comprising: a substrate; an IC mounted on the substrate; a submount formed to protrude on the substrate; an optical device for outputting or receiving an optical signal provided on the submount; a block having an optical waveguide formed on the substrate; And connection means for electrically connecting the optical element and the IC,

And a heat shielding means for shielding heat from the substrate between the optical element and the IC is formed.
The method according to claim 1,

Wherein the heat terminal means is a trench formed in the substrate between the optical element and the IC.
The method according to claim 1 or 2,

Wherein the heat terminal means is a separating wall formed on the substrate between the optical element and the IC.
The method according to any one of claims 1 to 3,

Wherein a heat spread is formed on the lower portion of the optical element and the substrate on the lower portion of the IC, respectively.
The method of claim 4,

Wherein the heat spread is a flexible graphite sheet.
The method of claim 2,

Wherein the trench is filled with a thermal conductive material.
The method of claim 6,

Wherein the thermal barrier material has a difference in thermal expansion coefficient from a material constituting the substrate to less than 5%.
The method of claim 7,

Wherein the thermal barrier material is a nanofiber web having a plurality of pores by electrospinning a polymer material.
The method of claim 8,

Wherein the nanofibers further comprise an insulating filler for enhancing strength.
The method of claim 9,

The heat insulating filler is made of SiO 2, SiON, Si 3 N 4, HfO 2, ZrO 2, Al 2 O 3, TiO 2, Ta 2 O 5, MgO, Y 2 O 3, BaTiO 3, ZrSiO 4, HfO 2 And at least one particle selected from the group consisting of glass fibers, graphite, rock wool, and clay.