JP3789232B2 - Optical module assembling apparatus and assembling method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an assembly of an optical module, and more particularly to a technique effective when applied to the automation of assembly of an optical module.
[0002]
[Prior art]
In today's information society, the types of information to be exchanged are diversified and the amount thereof is dramatically increased, and communication means for transmitting a large amount of information is required to have a larger capacity and higher speed. Optical communication using an optical fiber is regarded as important as such a large-capacity and high-speed communication means, and plans for expanding the optical communication network and installing an optical fiber up to the end of a subscriber system are in progress. As such an optical communication terminal device, an optical module having a hybrid structure in which an optical element such as an LD (Laser Diode) and a PD (Photo Diode) and an optical fiber are fixedly mounted on the same substrate is used.
[0003]
In assembling such an optical module, an optical fiber for transmitting laser light is fixed to a substrate, and light from an LD or PD is emitted or received on the optical fiber, and the maximum value of the incident power or output power obtained is A method of aligning and fixing to the obtained position is employed, and such a method of performing alignment while actually operating the optical element is called active alignment.
[0004]
[Problems to be solved by the invention]
However, such active alignment requires adjustment for each individual optical module, which is a major obstacle to mass production. For this reason, it is desirable to assemble the optical module by passive alignment that performs alignment without operating the optical element, but at present, the required alignment accuracy has not been achieved. The assembly of such an optical module is disclosed in Japanese Patent Application No. 6-308635, and also described in the spring issue of “TECHNICAL REPORT” issued by Hitachi Tokyo Electronics Co., Ltd.
[0005]
Further, since such assembly is performed, it is difficult to automate the work, and it is necessary to improve the mass productivity in order to spread the optical module in the future.
[0006]
An object of the present invention is to provide a technique capable of highly accurately assembling an optical module by passive alignment.
Another object of the present invention is to provide a technique capable of automating assembly by passive alignment of an optical module.
The above and other problems and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.
[0007]
[Means for Solving the Problems]
Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
An optical module assembling apparatus comprising a stage for fixing a substrate on which an optical element is mounted, and a bonding unit that holds the optical element and aligns and fixes the optical element to the substrate fixed to the stage. A detection unit for recognizing the position of the substrate fixed to the optical element and the stage, and a bonding head for aligning and fixing the optical element to the substrate based on positional information obtained by the detection unit. Have.
[0008]
According to the above-described means, the optical element can be fixed to the substrate with high accuracy by passive alignment, so that the assembly time is shortened and automation is possible. For this reason, the productivity of the optical module is improved.
[0009]
Embodiments of the present invention will be described below.
Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a configuration of an optical module assembling apparatus according to an embodiment of the present invention.
The optical module assembling apparatus of the present embodiment includes a substrate supply means 2 for supplying a semiconductor substrate 1 on which optical elements are mounted, an element supply means 4 for supplying optical elements 3 such as LD 3a and PD 3b, and the like. It comprises a bonding unit for aligning and fixing the optical element 3 to the semiconductor substrate 1 and a substrate discharging means 7 for transferring the semiconductor substrate 1 to which the optical element 3 has been fixed. The bonding unit includes a stage 5 for fixing the supplied semiconductor substrate 1 and a bonding head 6 for holding the optical element 3 and aligning and fixing the optical element 3 to the semiconductor substrate 1 fixed to the stage 5. have.
[0011]
As a substrate supply means, a wafer table 8 on which a wafer in which individual semiconductor substrates 1 that have been diced are integrated by a stretchable film is placed, and a wafer for obtaining positional information of the semiconductor substrate 1 on the wafer table 8 The recognition device 9 includes a substrate supply collet 10 that holds the semiconductor substrate 1 in accordance with the position information and transfers it to the stage 5. As the operation progresses, the wafer table 8 moves in a plane in the XY directions and supplies the supplied semiconductor substrate 1. Move to position. The position of the semiconductor substrate 1 to be supplied after movement is set as position information by the wafer recognition device 9, and the substrate supply collet 10 picks up the semiconductor substrate 1 based on this position information and transfers it onto the stage 5. The transferred semiconductor substrate 1 is pressed by the fixing member 11 from two orthogonal directions (only one direction is shown in FIG. 1), and is fixed to the bonding position by the side wall 12 and the fixing member 11 of the stage.
[0012]
The element supply means 4 includes a chip tray table 14 on which a tray 13 in which individual diced optical elements 3 are individually accommodated, and an element recognition device 15 for obtaining positional information of the optical elements on the chip tray table. As the work progresses, the chip tray table 14 moves in a plane in the XY directions and the supplied optical element 3 is moved to the supply position. The position of the supplied optical element 3 after the movement is set as position information by the element recognition device 15, and the bonding head 6 adsorbs the optical element 3 based on this position information and transfers it onto the stage 5.
[0013]
An infrared light source 17 such as a halogen lamp and a detection unit 18 are provided as a stage position recognition device 16. The angle of the light from the infrared light source 17 is changed by a mirror 19 and irradiated from the back surface of the semiconductor substrate 1. The position information of the semiconductor substrate 1 is obtained by the detection unit 18 from the infrared image obtained through the transmission. The position information of the transferred optical element 3 is obtained by the detection unit 18 from a direct view image obtained by the light of a visible light source (described later).
[0014]
Based on the position information thus obtained, the bonding head 6 moves in the XY direction and rotates around the Z axis orthogonal to the XY direction to align the planar position and the mounting angle of the optical element 3 with respect to the semiconductor substrate 1. Do.
[0015]
After the alignment is completed, the semiconductor substrate 1 and the optical element 3 are fixed to each other by junction with Au—Sn solder.
[0016]
The substrate discharge means 7 includes a substrate discharge collet 21 for transferring the optical module 20 to which the optical element 3 is fixed, and a module tray table 23 for placing a tray 22 for storing the transferred optical module 20. As the module tray table 23 moves in the XY direction, the module tray 22 is moved to the accommodation position of the optical module 20 to be transferred.
[0017]
FIG. 2 is a longitudinal sectional view showing the bonding head 6 according to this embodiment.
The bonding head 6 has a collet holder 26 attached to an arm 24 movable in the X and Y directions via a rotary bearing 25. A hollow cylindrical lens barrel 27 is moved in the vertical direction, that is, in the Z direction and Z direction with respect to the collet holder 26. It is configured to rotate around an axis.
[0018]
2, the lens barrel 27 comes into contact with two bearings 28 attached to the collet holder 26, and is urged by an urging means such as a pressure adjusting spring in the direction of the arrow. Yes. Accordingly, the lens barrel 27 is rotated around the Z axis by the collet rotating pulley 29 while always maintaining a certain positional relationship with the collet holder 26.
[0019]
The bonding head 6 is moved up and down by a Z-axis moving mechanism (not shown) that comes into contact with the collar 30 attached to the upper end of the lens barrel 27.
[0020]
A bonding collet 31 is attached to the tip of the lens barrel 27. The bonding collet 31 is provided with an objective lens 32 for obtaining an enlarged image of the optical element and a vacuum collet 33 for adsorbing the optical element. The vacuum collet 33 normally handles a small optical element 3 of 0.3 mm to 0.6 mm, so that a thin suction plate 34 having small suction holes and a pressure difference between the inside of the vacuum collet 33 and the outside air. And a support plate 35 for preventing deformation.
[0021]
In this bonding head 6, the position information of the optical element 3 is obtained by illuminating the optical element 3 adsorbed on the vacuum collet 33 by the visible light source 36 provided above the bonding collet 31, and reflecting the image on the half mirror 37. It is obtained by being transmitted to the recognition camera which is the detection unit 18. As for the position information of the semiconductor substrate 1, an infrared image transmitted through the stage 5 and the semiconductor substrate 1 is reflected to the half mirror 37 through the bonding collet 31 and the lens barrel 27 and transmitted to the recognition camera as the detection unit 18. Obtained by. At this time, the light from the visible light source 36 is blocked by the shutter 38.
[0022]
Further, since the semiconductor substrate 1 and the optical element 3 are separated from each other at the position of alignment, the focus of the recognition camera is different, and a clear image cannot be obtained unless the focus is changed. For this reason, the focus correction lens 39 is provided in the present embodiment. Usually, the optical element 3 with respect to the position of the semiconductor substrate 1 is at a constant height, the presence or absence of focus correction lens 39, to obtain a readily sharp image for any of the semiconductor substrate 1 and the optical element 3 Can do.
[0023]
In the present embodiment, the optical system including the illumination light source 36, the detection unit 18, and the optical element that adjusts the optical path between these and the detection target is configured integrally with the bonding head 6. You may provide further the position adjustment apparatus rotated or moved up and down with respect to it. It may also be provided independently such optical system and the position adjusting device without integrated with bonding heads.
[0024]
Next, the alignment in the present embodiment will be described more specifically with reference to FIG. The semiconductor substrate 1 is provided with four indexes 40 for alignment and a fiber groove 42 for fixing the optical fiber 41, and the LDs 3a and PD3b are also provided with indexes 43 and 44 for alignment at two locations, respectively. It has been. Using these indexes 43, the LD 3a is fixed in alignment with a predetermined position of the semiconductor substrate 1.
[0025]
In (a) in the figure, the LD 3 a emits laser light with a slight angle with respect to the optical axis of the optical fiber 41 in order to prevent loss due to reflection from the end face of the optical fiber 41. Accordingly, the PD 3b for monitoring the laser beam from the rear surface of the LD 3a is also fixed on the same axis as the LD 3a. In (b) in the figure, the LD 3a emits a laser beam coaxially with the optical axis of the optical fiber 41 in order to simplify the process. Accordingly, the PD 3b for monitoring the laser beam from the rear surface of the LD 3a is also fixed on the same axis as the LD 3a.
[0026]
The index 40 and the fiber groove 42 of the semiconductor substrate 1 are grooves having a triangular cross section by utilizing the directionality of etching by the crystal plane of the semiconductor. For this reason, when infrared light is transmitted, it is reflected by the slope of each index 40. Therefore, since infrared light does not pass through each index 40 portion, each index 40 is recognized as a dark part in the infrared image. Become.
[0027]
The optical fiber 41 is fixed to the fiber groove 42 after the optical element 3 is attached. However, since the fiber groove 42 has a triangular cross section, the optical fiber 41 is pressed and fixed from above to fix the optical fiber 41 and the optical fiber 41. The position with the fiber 41 is fixed with high accuracy.
[0028]
Further, since the index 40 of the semiconductor substrate 1 is performed using the same mask in the same process as the fiber groove 42, the fiber groove 42 and the index 40 of the semiconductor substrate 1 are always kept in a certain positional relationship.
[0029]
Similarly, since the indexes 43 and 44 of the LD 3a and PD 3b are formed by the element forming process of the light emitting part or the light receiving part, the light emitting part or light receiving part and the indexes 43 and 44 of the LD 3a and PD 3b are always in a fixed positional relationship. Is preserved. However, since the light emitting surface of the LD 3a is formed by cleavage, the positional relationship between the light emitting surface and the index 43 of the LD 3a is not a constant positional relationship with sufficient accuracy. In addition, it is difficult to clearly capture the light emitting surface in an infrared transmission image.
[0030]
For this purpose, in the present embodiment, a visible light source 36 is provided, and the light source 36 is illuminated to obtain position information of the light emitting surface. Based on the position information of the light emitting surface and the position information of the index 43 of the LD 3a, the LD 3a is aligned with the fiber groove 42 by moving the arm 24 and rotating the lens barrel 27 so as to have a fixed positional relationship. Then, the LD 3 a is fixed to the semiconductor substrate 1. Thereafter, similarly, based on the position information of the fixed LD 3 a and the position information of the index 44 of the PD 3 b, the PD 3 b is aligned so as to have a certain positional relationship, and the PD 3 b is fixed to the semiconductor substrate 1.
[0031]
Next, the optical module 20 in which the LD 3a and the PD 3b are fixed to the semiconductor substrate 1 in this way is sealed in a package. FIG. 4 is a perspective view illustrating a package sealing state of the optical module.
[0032]
The optical module 20 is housed and fixed in a package 45 such as ceramic. Pins 46 serving as external terminals of the optical module 20 when mounted on the mounting substrate are fixed to the package 45, and the pins 46 are provided with electrodes 48 provided inside the package 46 by wiring 47 formed in the package 45. And continuity.
[0033]
On the other hand, a plurality of wirings 49 are provided on the semiconductor substrate 1, and the electrode 50 provided at one end of the wiring 49 and the electrode 48 of the package 45 are electrically connected by wire bonding or the like. The other end of the wiring 49 provided on the semiconductor substrate 1 is electrically connected to the LD 3a or PD 3b. The LD 3a and PD 3b are fixed to the electrode formed at the other end of the wiring 49 by junction down, whereby one electrode of the LD 3a or PD 3b is connected to the wiring 49, and the other electrode is bonded to each other. A wire 51 is connected to an electrode 52 formed on the other end of the wiring 49 of the semiconductor substrate 1. In this way, the fixing of the semiconductor substrate 1 and the wiring connection are completed.
[0034]
The optical fiber 41 is inserted into the package 45 from the insertion hole 53 of the package 45, pressed against the fiber groove 42 of the semiconductor substrate 1, and fixed by a method such as resin coating, and the insertion hole 53 is also sealed by this resin coating. After the optical fiber 41 is fixed, the package 41 covers the opening of the package 41 with a lid 54 and seals the lid 54 and the package 41 with solder or the like.
[0035]
Although the invention made by the present inventor has been specifically described based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Of course.
[0036]
For example, the optical module is not limited to the one on which LD and PD are mounted, and the present invention can be applied to one on which only LD or PD is mounted. But it can be applied.
[0037]
【The invention's effect】
The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
(1) According to the present invention, there is an effect that the optical element can be aligned with high accuracy by the passive alignment on the semiconductor substrate of the optical module.
(2) According to the present invention, the effect (1) has an effect that the productivity of the optical module can be performed in a short time.
(3) According to the present invention, there is an effect that the assembly of the optical module can be automated.
(4) According to the present invention, the effects (2) and (3) have the effect of improving the productivity of the optical module.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an optical module assembling apparatus according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing a bonding head of an optical module assembling apparatus according to an embodiment of the present invention.
FIG. 3 is a plan view for explaining alignment in the optical module according to the embodiment of the present invention.
FIG. 4 is a perspective view for explaining a package sealing state of an optical module according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Substrate supply means, 3 ... Optical element, 3a ... LD, 3b ... PD, 4 ... Element supply means, 5 ... Stage, 6 ... Bonding head, 7 ... Substrate discharge means, 8 ... Wafer table, DESCRIPTION OF SYMBOLS 9 ... Wafer recognition apparatus, 10 ... Substrate supply collet, 11 ... Fixing member, 12 ... Side wall, 13, 22 ... Tray, 14 ... Chip tray table, 15 ... Element recognition apparatus, 16 ... Stage recognition apparatus, 17 ... Infrared light source, DESCRIPTION OF SYMBOLS 18 ... Detection unit, 19 ... Mirror, 20 ... Optical module, 21 ... Substrate discharge collet, 23 ... Module tray table, 24 ... Arm, 25 ... Rotating bearing, 26 ... Collet holder, 27 ... Lens barrel, 28 ... Bearing bearing, 29 ... Collet rotating pulley, 30 ... 鍔, 31 ... Bonding collet, 32 ... Objective lens, 33 ... Vacuum collet, 34 ... Suction plate, 35 ... Holding plate, 36 ... Visible light source, 37 ... Half mirror, 38 ... Shutter, 39 ... Focus correction lens, 40, 43, 44 ... Index, 45 ... Package, 46 ... Pin, 47, 49 ... Wiring, 48, 50, 52 ... Electrode, 51 ... Bonding wire, 53 ... Insertion hole, 54 ... Lid.

Claims (6)

An optical module assembly apparatus comprising: a stage for fixing a substrate on which an optical element is mounted; and a bonding unit that holds the optical element and aligns and fixes the optical element to the substrate fixed to the stage,
A detection unit for recognizing the position of the substrate fixed to the optical element and the stage, and a bonding head for aligning and fixing the optical element to the substrate based on position information obtained by the detection unit; Have
The illumination light source of the detection unit illuminates the first illumination light source that illuminates the first light that passes through the substrate and the optical element, and the optical element that illuminates the second light that does not penetrate the optical element. An assembly device for an optical module, comprising: a second illumination light source.   The optical module assembling apparatus according to claim 1, further comprising a visible light source as the second illumination light source, and an infrared transmissive illumination light source as the first illumination light source.   Prior to recognizing the first light and performing an alignment operation between the substrate and the optical element, position information of the optical element at the time of the alignment operation is obtained using the second light. The optical module assembling apparatus according to claim 1 or 2. An optical module assembling method comprising: a stage for fixing a substrate on which an optical element is mounted; and a bonding unit for holding the optical element and aligning and fixing the optical element to the substrate fixed to the stage,
Recognizing the position of the substrate and the optical element on the stage using the first light that irradiates the optical element and the second light that does not pass through the optical element, and performs an alignment operation,
Method of assembling an optical module that is characterized by using an infrared transmitting light source as the illumination light source of the first light. An optical module assembling method comprising: a stage for fixing a substrate on which an optical element is mounted; and a bonding unit for holding the optical element and aligning and fixing the optical element to the substrate fixed to the stage,
The bonding unit has a detection unit for recognizing the position of the substrate fixed to the optical element and the stage, and a bonding head for aligning and fixing the optical element to the substrate,
The detection unit recognizes the position of the substrate and the optical element on the stage using the first light that irradiates the optical element and the second light that does not pass through the optical element,
An infrared transmission light source is used as the illumination light source of the first light, and the bonding collet aligns and fixes the optical element to the substrate based on positional information obtained by the detection unit. Module assembly method. 6. The optical module assembling method according to claim 4 , further comprising a visible light source as the illumination light source for the second light.

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