JP2008216712A - Packaging method for optical component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging method for an optical component by which a semiconductor device mounted with an optical element can be fixed to a printed wiring board without increasing optical coupling loss. <P>SOLUTION: In a first step, solder 30 is supplied to the semiconductor device 10 or printed wiring board 20 and in a second step, a resin pool 40 is formed using light-transmissive resin which is not softened at reflow temperature of the solder 30 and has heat resistance. After the semiconductor device 10 is mounted on the printed wiring board 20 in a third step, the resin pool 40 is cured in a fourth step to fix an optical coupling, and the solder 30 is reflowed in a fifth step to fix an electric coupling. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical component mounting method for mounting a semiconductor device mounted with an optical element on a printed wiring board provided with an optical waveguide.

  In recent years, in the field of integrated devices made of semiconductors, progress toward high speed and high density has been remarkable, and interconnections using conventional electrical wiring cannot expect sufficient characteristics due to signal delay, attenuation, interference, etc. Is a problem. This problem is said to be an IO bottleneck, and optical interconnection technology has attracted attention in order to solve this problem. The optical interconnection technology is considered to be applied not only between communication devices and between boards in a communication device, but also between integrated circuit elements in one board.

  As a conventional optical circuit board for realizing on-board optical interconnection, a multilayer printed board on which an optical waveguide disclosed in Patent Document 1 is formed is known. Here, the signal light emitted in the direction perpendicular to the substrate from the surface emitting element (VCSEL) mounted on the substrate surface is reflected by the optical path conversion mirror formed in the optical wiring to guide the optical waveguide. The guided signal light is reflected by another optical path conversion mirror and received by a surface-receiving optical element (planar photodiode).

  In such an optical circuit board, the optical coupling loss in the light emitting element and the light receiving element greatly affects the attenuation of the signal. Therefore, in order to suppress such signal attenuation, an optical coupling means for performing alignment between the optical element and the optical waveguide with high accuracy of several μm is required.

  As a conventional method for mounting an optical component for performing high-precision alignment as described above on an optical circuit board, for example, the one disclosed in Patent Document 2 is known. In Patent Document 2, a component is arranged at a predetermined mounting position by a self-alignment action of solder.

Here, the self-alignment action is an action of trying to exist in a more stable shape near the center of the opening of the solder resist due to the fluidity of the solder during the reflow process because the solder resist layer repels the solder. As a result, even if a positional deviation occurs before reflow, the position is corrected by the above self-alignment action during reflow.
JP 2006-120956 A JP 2002-296435 A

  However, the conventional mounting method has the following problems. In the method of performing mounting positioning using self-alignment as disclosed in Patent Document 2, when the solder resist layer is formed on the electric circuit, the alignment accuracy between the electric circuit and the solder resist layer is low. It is necessary to investigate the flow characteristics of the solder during reflow and grasp the position change due to self-alignment, and to reflect this in the design. However, it is important to control the position change due to self-alignment with a high accuracy of about several μm. There was a problem that it was extremely difficult.

  Accordingly, the present invention has been made to solve these problems, and mounting of an optical component capable of fixing a semiconductor device mounted with an optical element to a printed wiring board without increasing optical coupling loss. It aims to provide a method.

  According to a first aspect of the optical component mounting method of the present invention, there is provided an optical component mounting method for fixing a semiconductor device on which an optical element is mounted to a printed wiring board having an optical waveguide, the semiconductor device and the print A first step of supplying solder to a part to be electrically coupled to at least one of the wiring boards; and a light-transmitting resin having heat resistance against the reflow temperature of the solder in an uncured state with the optical element. The second step of filling a portion where the optical waveguide is optically coupled to form a resin reservoir and the portion where the solder is electrically coupled are located between the optical reservoir and the optical reservoir. A third step of positioning and placing the semiconductor device on the printed wiring board so as to be positioned between the parts to be coupled; and the optical element and the light guide by curing the resin pool. A fourth step of optically coupling and fixing the path, and a fifth step of reflowing the solder to electrically couple the semiconductor device and the printed wiring board. Step 4 is performed before the fifth step.

  According to another aspect of the optical component mounting method of the present invention, in the second step, the optically coupled portion on the printed wiring board is filled with the light transmissive resin to form the resin pool. It is characterized by that.

  According to another aspect of the optical component mounting method of the present invention, in the second step, the light transmissive resin is filled on the semiconductor device so as to cover the optical element, thereby forming the resin pool. Features.

  According to another aspect of the optical component mounting method of the present invention, in the second step, the optically coupled portion on the printed wiring board is filled with the light transmissive resin to form the resin pool. In addition, another resin pool is formed by filling the semiconductor device with the light-transmitting resin so as to cover the optical element.

  According to another aspect of the optical component mounting method of the present invention, after all the first to fifth steps are completed, an underfill resin is filled in a gap between the semiconductor device and the printed wiring board. These steps are further executed.

  As described above, according to the present invention, since the optical coupling position is fixed using the light-transmitting resin and the electrical coupling is performed, the semiconductor device on which the optical element is mounted is provided. It is possible to provide an optical component mounting method that can be fixed to a printed wiring board without reducing the optical coupling efficiency.

  Further, according to the optical component mounting method of the present invention, since the optical coupling is performed using the light transmissive resin having heat resistance against the reflow temperature of the solder, the electrical reflow is performed by the solder reflow. Even when performing simple coupling, it is possible to prevent a positional shift due to self-alignment and prevent a decrease in optical coupling efficiency.

  A configuration of an optical component mounting method according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

  When mounting a semiconductor device on which an optical element is mounted on a printed wiring board having an optical waveguide, two steps are required: a step of electrically coupling the semiconductor device and the printed wiring board and a step of optically coupling the semiconductor device and the printed wiring board. Become. The optical component mounting method of the present invention is capable of suitably maintaining the optical coupling efficiency by preventing the occurrence of displacement in the optical coupling state in the process of electrical coupling. is there.

  Below, the mounting method of the optical component of this invention is demonstrated taking a semiconductor device and a printed wiring board as shown in FIG. 2 as an example. A semiconductor device 10 shown in FIG. 2A has an optical element 12 mounted on one surface of an optical element mounting substrate 11, and an IC 13 for driving the optical element 12 and the like mounted on the other surface. Is sealed with a module sealing resin 14. An electrical coupling portion (connection terminal) 15 for electrical coupling with the printed wiring board 20 is provided on the surface on which the optical element 12 of the optical element mounting substrate 11 is mounted.

  A printed wiring board 20 shown in FIG. 2B includes an electric circuit board 21 and an optical waveguide 22 that guides light in a direction parallel to the electric circuit board 21, and a reflecting surface 23 at a predetermined position of the optical waveguide 22. Is provided. The electric circuit board 21 has a structure including conductor pattern layers 21b on both sides of an insulating layer 21a. The optical waveguide 22 includes a core layer 22a for guiding light and a cladding layer 22b surrounding the core layer 22a. It has a structure. The electrical circuit board 21 is provided with an electrical coupling portion 25 for electrical coupling with the semiconductor device 10.

  The reflection surface 23 provided in the middle of the optical waveguide 22 changes the optical axis of the optical waveguide 22 in the vertical direction. By arranging the optical element 12 in the vertical direction, the light emitted from the optical element 12 Can be guided to the core layer 22a of the optical waveguide 22, or the light guided through the core layer 22a can be emitted to the optical element 12.

  The printed wiring board 20 is formed with a hole 26 in which the electric circuit board 21 is removed and the optical waveguide 22 is exposed. On the extension, the optical axis of the optical waveguide 22 is changed in the vertical direction by the reflecting surface 23. Is formed so that the hole 26 is located in the hole. That is, the bottom of the hole 26 is the light input / output part 27 of the optical waveguide 22.

  A method for mounting an optical component according to the first embodiment of the present invention for mounting the semiconductor device 10 shown in FIG. 2 on the printed wiring board 20 will be described below with reference to FIG. In the optical component mounting method of the present embodiment, as a first step, the solder 30 is supplied to at least one of the electrical coupling portion 15 of the semiconductor device 10 and the electrical coupling portion 25 of the printed wiring board 20. In FIG. 1A, solder 30 is supplied to the electrical coupling portion 15 of the semiconductor device 10.

  In the next second step, a predetermined light-transmitting resin is used to fill the holes 26 of the printed wiring board 20 in an uncured state to form the resin pool 40. FIG. 1B shows a state where the resin reservoir 40 is formed in the hole 26 of the printed wiring board 20. Note that the second step may be performed prior to the first step.

  The resin reservoir 40 is formed by using a light-transmitting resin having heat resistance that does not soften at the reflow temperature of the solder 30 supplied to the electrical coupling portion 15. For example, epoxy resin, phenol resin, polyimide resin, polyester Thermosetting resins such as resins, bismaleimide resins, polyolefin resins, polyphenylene ether resins, polyphenylene resins, and fluorine resins can be used.

  In the next third step, the semiconductor device 10 is placed on the printed wiring board 20 (FIG. 1C). At this time, the resin reservoir 40 formed in the hole 26 of the printed wiring board 20 covers the optical element 12 mounted on the semiconductor device 10, and the optical axis of the optical element 12 passes through the reflecting surface 23 and the optical waveguide 22. Positioned to coincide with the optical axis. Further, the solder 30 supplied to the electrical coupling portion 15 of the semiconductor device 10 is positioned so as to come into contact with the electrical coupling portion 25 on the printed wiring board 20.

  In the next fourth step, the resin reservoir 40 sandwiched between the semiconductor device 10 and the printed wiring board 20 is cured, and thereby the optical element 12 and the optical waveguide 22 are optically coupled and fixed. When a thermosetting resin is used as the light transmissive resin for forming the resin reservoir 40, the resin reservoir 40 is cured by heating to a predetermined temperature. When a light curable resin is used as the light transmissive resin for forming the resin reservoir 40, the resin reservoir 40 is cured by irradiating light.

  Further, in the fifth step, the electrical coupling portion 15 of the semiconductor device 10 and the electrical coupling portion 25 of the printed wiring board 20 are electrically coupled by reflowing the solder 30 (FIG. 1D). In the optical component mounting method of the present embodiment, it is important to perform the fourth step before the fifth step. By performing the fourth step first, the optical coupling between the optical element 12 and the optical waveguide 22 is fixed in advance, and then the electrical coupling of the fifth step is performed. The optical coupling between the optical element 12 and the optical waveguide 22 is prevented from being displaced.

  Since the resin reservoir 40 used for optical coupling between the optical element 12 and the optical waveguide 22 is made of a light-transmitting resin having heat resistance that does not soften at the reflow temperature of the solder 30, Even when the solder 30 is reflowed, the resin reservoir 40 is not softened, and the optical coupling between the optical element 12 and the optical waveguide 22 can be prevented from being displaced due to the self-alignment of the solder 30.

An optical component mounting method according to the second embodiment of the present invention will be described below with reference to FIG.
In the first embodiment, the solder 30 is supplied to at least one of the electrical coupling portion 15 of the semiconductor device 10 and the electrical coupling portion 25 of the printed wiring board 20 in the first step (FIG. 3A )), The resin reservoir 40 is formed in the hole 26 of the printed wiring board 20 in the second step. However, in the optical component mounting method of this embodiment, the resin reservoir 40 is formed on the semiconductor device 10. I have to.

  That is, in the second step of this embodiment, a predetermined light transmitting resin is used to fill the semiconductor device 10 so as to cover the optical element 12 in an uncured state, thereby forming the resin pool 40. . A state in which the resin reservoir 40 is formed on the semiconductor device 10 is shown in FIG. In the present embodiment, the second step may be performed before the first step.

  In the next third step, the semiconductor device 10 is placed on the printed wiring board 20 (FIG. 3C), and in the fourth step, the resin reservoir 40 is cured, so that the optical element 12 and the optical waveguide 22 are separated. The optical coupling is fixed, and the solder 30 is reflowed in the fifth step to fix the electrical coupling (FIG. 3D).

  In the optical component mounting method of the present embodiment, it is important to perform the fourth step before the fifth step. Thus, since the electrical coupling is performed after the optical coupling between the optical element 12 and the optical waveguide 22 is fixed, the optical coupling between the optical element 12 and the optical waveguide 22 is prevented from being displaced. be able to. Further, since the resin reservoir 40 is made of a light-transmitting resin having heat resistance that does not soften at the reflow temperature of the solder 30, misalignment due to self-alignment during reflow of the solder 30 can be prevented.

An optical component mounting method according to the third embodiment of the present invention will be described below with reference to FIG.
Also in this embodiment, the method for forming the resin pool 40 in the second step is different from the first embodiment and the second embodiment. In the present embodiment, the solder 30 is supplied to at least one of the electrical coupling portion 15 of the semiconductor device 10 and the electrical coupling portion 25 of the printed wiring board 20 in the first step (FIG. 4A), and then the second step. In this step, the resin reservoir 40 is formed on both the semiconductor device 10 and the printed wiring board 20.

  In the second step of the present embodiment, a predetermined light-transmitting resin is used to fill the semiconductor device 10 so as to cover the optical element 12 in an uncured state, thereby forming the resin reservoir 40a. Filling the voids 26 of the printed wiring board 20 to form the resin reservoir 40b. FIG. 4B shows a state in which the resin reservoir 40a is formed on the optical element 12 of the semiconductor device 10 and the resin reservoir 40b is also formed in the hole 26 of the printed wiring board 20.

  As described above, in this embodiment in which the resin pools 40a and 40b are formed on both the semiconductor device 10 and the printed wiring board 20, the semiconductor device 10 is placed on the printed wiring board 20 in the next third step. At this time, the resin reservoirs 40a and 40b come into contact with each other to be integrated (FIG. 4C). As a result, the optical element 12 and the hole 26 can be reliably optically coupled with the light transmissive resin. Similarly, the resin pool 40 is cured in the fourth step to fix the optical coupling between the optical element 12 and the optical waveguide 22, and the solder 30 is reflowed in the fifth step to fix the electrical coupling. (FIG. 4D).

  In the optical component mounting method of the present embodiment, it is important to perform the fourth step before the fifth step. Thus, since the electrical coupling is performed after the optical coupling between the optical element 12 and the optical waveguide 22 is fixed, the optical coupling between the optical element 12 and the optical waveguide 22 is prevented from being displaced. be able to. Further, since the resin reservoir 40 is made of a light-transmitting resin having heat resistance that does not soften at the reflow temperature of the solder 30, misalignment due to self-alignment during reflow of the solder 30 can be prevented.

An optical component mounting method according to the fourth embodiment of the present invention will be described below with reference to FIG.
The optical component mounting method of the present embodiment can be applied to any of the mounting methods of the first to third embodiments, and all the processes from the first step to the fifth step are finished. After that, another process is added.

  FIG. 5A shows the resin pool 40 and the solder after the semiconductor device 10 is placed on the printed wiring board 20 using any of the mounting methods of the first to third embodiments. The state fixed at 30 is shown. In the optical component mounting method of the present embodiment, the following sixth step processing is further performed from the state of FIG.

  As a sixth step, the underfill resin 50 is filled in the gap between the semiconductor device 10 and the printed wiring board 20 (FIG. 5B). Since the gap between the semiconductor device 10 and the printed wiring board 20 is small, the underfill resin 50 can be filled into the gap by capillary action.

  In particular, it is preferable to use a thermosetting epoxy resin as the underfill resin 50, and this can be filled in the gap between the semiconductor device 10 and the printed wiring board 20 by capillary action. A thermosetting epoxy resin is a material that has low linear expansion, small thermal deformation, and stable dimensions.

  As described above, by using a thermosetting epoxy resin, for example, a mismatch of linear expansion between the semiconductor device 10 and the printed wiring board 20 occurs due to heat generated repeatedly from the semiconductor device 10, and the resin pool 40 is strained. As a result, the optical coupling efficiency is lowered, or the solder 30 is cracked due to strain and finally broken, so that the reliability can be improved.

  In the optical component mounting method of the present embodiment, the solder 30 is supplied to the semiconductor device 10 or the printed wiring board 20 in the first step. Below, the supply method of the solder 30 is demonstrated in detail using FIG.

  As an example of a method for supplying the solder 30, a case where the solder 30 is supplied to the electrical coupling portion 15 of the semiconductor device 10 in the first step will be described. In FIG. 6, ball-shaped solders 30 are supplied to a plurality of electrical coupling portions 15 provided in the semiconductor device 10. At this time, since an oxide film is formed on the solder 30 and the electrical coupling portion 25, the electrical coupling portion 25 of the printed wiring board 20 is facilitated in order to facilitate the joining with the electrical coupling portion 25 of the printed wiring board 20. In addition, it is preferable to apply the cream solder 31.

  As described above, the ball-shaped solder 30 is supplied to the electric coupling portion 15 of the semiconductor device 10, and the cream solder 31 is previously applied to the electric coupling portion 25 of the printed wiring board 20 to which the ball-shaped solder 30 is not supplied in advance. By applying, the flux component contained in the cream solder 31 is activated at the time of reflowing in step 5, thereby removing the oxide film formed on the solder 30 and the electrical coupling portion, and the solder 30 and the cream. The solder 31 is melted and reliably joined to the electrical coupling portion 25 of the printed wiring board 20.

  Note that the description in the present embodiment shows an example of an optical component mounting method according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of the optical component mounting method in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

It is a figure explaining the mounting method of the optical component which concerns on the 1st Embodiment of this invention. 1 is a structural diagram of a semiconductor device on which an optical element is mounted and a printed wiring board including an optical waveguide. It is a figure explaining the mounting method of the optical component which concerns on the 2nd Embodiment of this invention. It is a figure explaining the mounting method of the optical component which concerns on the 3rd Embodiment of this invention. It is a figure explaining the mounting method of the optical component which concerns on the 4th Embodiment of this invention. It is a figure explaining the supply method of solder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor device 11 Optical element mounting substrate 12 Optical element 13 Driving IC
14 Module sealing resin 15, 25 Electrical coupling part 20 Printed wiring board 21 Electrical circuit board 22 Optical waveguide 23 Reflecting surface 26 Hole 27 Optical input / output part 30 Solder 31 Cream solder 40 Resin pool 50 Underfill resin

Claims (5)

An optical component mounting method for fixing a semiconductor device mounted with an optical element to a printed wiring board including an optical waveguide,
A first step of supplying solder to a portion to be electrically coupled to at least one of the semiconductor device and the printed wiring board;
A second step of forming a resin pool by filling a portion where the optical element and the optical waveguide are optically coupled in an uncured state with a light transmissive resin having heat resistance against the reflow temperature of the solder; ,
The semiconductor device is positioned and placed on the printed wiring board so that the solder is located between the electrically coupled portions and the resin pool is located between the optically coupled portions. A third step;
A fourth step of optically coupling and fixing the optical element and the optical waveguide by curing the resin reservoir;
A fifth step of reflowing the solder to electrically couple the semiconductor device and the printed wiring board;
An optical component mounting method, wherein at least the fourth step is performed before the fifth step. 2. The optical component according to claim 1, wherein, in the second step, the optically coupled portion on the printed wiring board is filled with the light transmissive resin to form the resin pool. 3. Implementation method. 2. The optical component mounting method according to claim 1, wherein in the second step, the resin pool is formed by filling the semiconductor device with the light-transmitting resin so as to cover the optical element. . In the second step, the optically coupled portion on the printed wiring board is filled with the light transmissive resin to form the resin pool, and the light transmissive resin covers the optical element. The method for mounting an optical component according to claim 1, further comprising: filling the semiconductor device with another resin pool. The sixth step of filling an underfill resin in a gap between the semiconductor device and the printed wiring board after completing all the steps from the first to the fifth is further performed. The method for mounting an optical component according to claim 1.

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