JP2005284302A - Packaging structure of optical parts - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging structure of optical parts with which optical axes are precisely aligned with each other by making optical transmission sections mutually closer while a packaging optical part that is to be packaged on a substrate through metallic bumps. <P>SOLUTION: In the packaging method of optical parts, an optical part 1, on which a first optical transmission section 3 and metallic bumps 2 are provided on the bottom surface, is packaged onto a substrate 4 on which a second transmission section 6 that transmits and receives to and from the first optical transmission section 3 is arranged and connecting electrodes 5, that are joined to the metallic bumps 2, are provided. The metallic bumps 2 are abutted to the connection electrodes 5 and loading and ultrasonic vibration are applied to the optical part 1 by a bonding tool 7 to metallically join the metallic bumps 2 to the connection electrodes 5. In the above metallic joining process, the heights of the electrodes of the metallic bumps 2 are reduced to make the bottom surface of the optical part 1 be close to the top surface of the substrate 4. Thus, the optical transmission sections are made closer to each other and the optical axes are precisely aligned with each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical component mounting structure in which an optical component such as an optical module for optical communication or an optical element is mounted on a substrate.

  In recent years, optical communication has been widely used to meet the demand for higher speed and larger capacity of information communication. For optical communication devices, optical components such as optical modules and optical elements that are not found in conventional telecommunications devices are used. These optical components are provided with a light transmission unit such as a light emitting unit and a light receiving unit in order to exchange light as a signal transmission medium with each other and with a substrate on which the optical component is mounted. When mounting these optical components on the substrate, the optical components are bonded to the substrate with the corresponding light transmitting portions facing each other. As a mounting form, a method of joining to a substrate by a metal bump such as a solder bump or a gold bump is used as in a normal BGA package or flip chip.

  However, the above-described method for mounting the optical component with metal bumps has the following disadvantages. First, problems in a method for performing solder bonding using solder bumps will be described. In order to ensure stable bonding quality in solder bonding, an appropriate amount of solder according to the size of the bonding portion is required. Therefore, the size of the solder bump is inevitably smaller than the lower limit size required for bonding quality. growing.

  However, when the size of the solder bumps is increased, a gap between the lower surface of the optical component after mounting and the upper surface of the substrate becomes large, and performance degradation due to increased attenuation during light transmission cannot be avoided. Further, in order to avoid this performance degradation, it is necessary to insert a lens or an optical amplifier between the optical component and the substrate, resulting in an increase in cost.

  In the method using gold bumps as the bumps, a pressure bonding method is used in which the gold bumps are pressed against the electrodes of the substrate and metal-bonded. According to this method, the gold bumps can be crushed by a large pressing load to reduce the bump height after mounting, and the gap between the lower surface of the optical component and the upper surface of the substrate can be reduced.

  However, when a large pressing load is applied in the pressure bonding, the substrate is easily deformed and the bump height is likely to vary, and it is difficult to keep the optical component after mounting and the substrate parallel. As a result, there is a problem in that the optical axes of the optical transmission parts of the optical component and the substrate cannot be accurately aligned in the state after mounting, and the optical transmission cannot be performed normally.

  As described above, in the mounting of the optical component in which the optical component is mounted on the substrate via the metal bump, it has been difficult to accurately align the optical axes by bringing the light transmitting portions closer to each other. It was.

  Accordingly, the present invention provides a mounting structure for an optical component capable of accurately aligning the optical axis by bringing the optical transmission parts close to each other in mounting the optical component on which the optical component is mounted on the substrate via the metal bump. With the goal.

The mounting structure for an optical component according to claim 1 is a first configuration in which an optical component having a first light transmission portion and a first electrode on a lower surface is exchanged with the first light transmission portion. 2 is a mounting structure of an optical component that is mounted on a substrate having a second electrode to which the first electrode is joined, and the first electrode is used as the second electrode. By applying a load and ultrasonic vibration to the optical component by contact, a lower surface of the first electrode is formed into a metal bonded surface with the upper surface of the second electrode. Since the height dimension of the first electrode or the second electrode is reduced, the gap between the lower surface of the optical component and the upper surface of the substrate is smaller than that before mounting, and the first electrode and the second electrode Around the joint with the electrode, the joint between the first electrode and the second electrode is reinforced and externally Shielding resin layer for blocking light is formed.

  According to the present invention, the first electrode of the optical component is brought into contact with the second electrode of the substrate, and a load and ultrasonic vibration are applied to the optical component so that the lower surface of the first electrode is the upper surface of the second electrode. In addition, the height dimension of the metal bumps is reduced and the lower surface of the optical component and the upper surface of the substrate are brought closer to each other, so that the light transmission portions can be brought closer to each other and the optical axis can be accurately aligned.

  1 is a process explanatory diagram of an optical component mounting method according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view of the optical component mounting structure according to Embodiment 1 of the present invention, and FIG. 3 is an embodiment of the present invention. It is sectional drawing of 1 optical component and a board | substrate.

  First, an optical component mounting method will be described with reference to FIG. In this optical component mounting method, an optical component such as an optical module or an optical element is bonded to a substrate via a metal bump, and an optical transmission portion provided on each of the optical component and the substrate is placed at an appropriate position for transmitting and receiving light. To align with.

  In FIG. 1A, a first light transmission unit 3 is provided at the center of the lower surface of the optical component 1, and metal bumps as first electrodes are provided on both sides of the first light transmission unit 3. 2 is provided. On the upper surface of the substrate 4 on which the optical component 1 is mounted, a second light transmission unit 6 that transmits and receives light to and from the first light transmission unit 3 is provided. On both sides, connection electrodes 5 are provided as second electrodes to which the metal bumps 2 are bonded.

  As the first light transmission unit 3, one having only a light emitting function, one having only a light receiving function, or one having both light emitting and light receiving functions is used depending on the type of the optical component 1. The second light transmission unit 6 is connected to a waveguide unit 6 a provided inside the substrate 4, and the waveguide unit 6 a is connected between the optical component 1 and another component mounted or connected to the substrate 4. Light is exchanged via

  When the optical component 1 is mounted on the substrate 4, as shown in FIG. 1B, the optical component 1 is held by the bonding tool 7, and the first light transmission unit 3 is attached to the second light transmission unit 6. The metal bump 2 is brought into contact with the connection electrode 5 in the aligned state. Thereafter, a downward load and a horizontal ultrasonic vibration are applied to the optical component 1 by the bonding tool 7. As a result, the lower surface of the metal bump 2 is metal bonded to the upper surface of the connection electrode 5 by solid layer diffusion bonding as shown in FIG.

In the metal bonding process, the bonding interface between the metal bump 2 and the connection electrode 5 is plastically deformed by the pressing load and ultrasonic vibration acting on the optical component 1 to reduce the height dimension. The gap between the lower surface of 1 and the upper surface of the substrate 4 is changed from a height dimension H1 in a state before mounting shown in FIG. 1B to a height dimension H2 in a state after metal bonding shown in FIG. To decrease. At this time, as compared with the conventional mounting method in which the optical component 1 is pressure-bonded by simply crushing the metal bumps 2 with a pressing load, the gap can be greatly reduced and the mounting can be completed. In the mounting process, when the substrate 4 is heated to about 150 ° C. together with the pressing load and the ultrasonic vibration, the mounting can be performed more efficiently.

  FIG. 2 shows a mounting structure in which the optical component 1 is thus mounted on the substrate 4 by ultrasonic bonding. In this mounting structure, the height of the metal bumps 2 is reduced so that the distance between the first light transmission unit 3 and the second light transmission unit 6 is as close as possible. In addition, since it is not necessary to apply an excessive pressing load during the mounting process, the variation in deformation of the substrate 4 and deformation of each metal bump is small, and the first light transmission unit 3 and the second light transmission unit 6 are parallel. The degree is secured with good accuracy. In this way, a mounting structure in which the first optical transmission unit 3 and the second optical transmission unit 6 are opposed to each other as close as possible with high positional accuracy and the optical axes are aligned with high accuracy can be realized. Attenuation at the time of light transmission between the component 1 and the substrate 4 can be prevented.

  In the above embodiment, the configuration example in which the optical component 1 provided with the metal bumps 2 is mounted on the substrate 4 provided with the connection electrodes 5 is shown. However, as shown in FIG. The optical component 1A provided with 2A may be mounted on the substrate 4A provided with the metal bump 5A on the upper surface by ultrasonic bonding in the same manner as shown in FIG.

(Embodiment 2)
FIG. 4 is a process explanatory diagram of the optical component mounting method according to the second embodiment of the present invention. In the second embodiment, when the same optical component 1 as in the first embodiment is mounted on the substrate 4, a sealing resin is supplied onto the substrate 4 in advance. The optical component 1 and the substrate 4 are the same as those shown in the first embodiment.

  In FIG. 4A, prior to the mounting operation in which the metal bump 2 is brought into contact with the connection electrode 5, a thermosetting resin adhesive such as an epoxy resin is provided around the connection electrode 5 on the upper surface of the substrate 4. 8 is supplied. When supplying the resin adhesive 8, a supply method is used in which an appropriate amount is supplied only to a predetermined range around the connection electrode 5 and the second light transmission unit 6 is not covered with the resin adhesive 8. . For example, there are a method of sticking a resin sheet pre-formed into a shape corresponding to the arrangement of the connection electrodes 5, a method of applying while controlling the application position using a dispenser capable of controlling the discharge amount with high accuracy, and the like. Used.

  In the mounting process, as shown in FIG. 4B, the optical component 1 is held by the bonding tool 7 as in the first embodiment, and the first light transmission unit 3 is positioned at the second light transmission unit 6. At the same time, the metal bump 2 is brought into contact with the connection electrode 5 through the resin adhesive 8. Thereafter, a downward load and a horizontal ultrasonic vibration are applied to the optical component 1 by the bonding tool 7. Thereby, the lower surface of the metal bump 2 is metal bonded to the upper surface of the connection electrode 5 by solid layer diffusion bonding as shown in FIG.

  Thereafter, the substrate 4 is heated to thermally cure the resin adhesive 8. In this resin curing process, the resin adhesive 8 crawls up to the lower surface of the optical component 1 along the surface of the metal bump 2. In this state, the resin adhesive 8 is thermally cured, thereby forming a sealing resin portion 8A arranged so as to surround the first light transmission portion 3 and the second light transmission portion 6.

  The sealing resin portion 8A reinforces the joint portion between the metal bump 2 and the connection electrode 5 after mounting, and light from the outside is in use in the first light transmission portion 3 and the second light transmission portion 6. It functions as a light-blocking resin layer that blocks the arrival at the opposite surface. Thereby, in addition to the effects shown in the first embodiment, it is possible to perform high-quality optical transmission in which external noise is reliably blocked.

In the above embodiment, the configuration example in which the optical component 1 provided with the metal bumps 2 is mounted on the substrate 4 provided with the connection electrodes 5 is shown. However, as shown in FIG. Even when the optical component 1A provided with 2A is mounted on the substrate 4A provided with the metal bump 5A on the upper surface, the mounting method shown in the second embodiment can be applied.

  According to the present invention, a load and ultrasonic vibration are applied to the optical component in a state where the first electrode of the optical component is in contact with the second electrode of the substrate, and the lower surface of the first electrode is applied to the second electrode. In addition to metal bonding to the upper surface of the substrate, the height dimension of the metal bumps is reduced, and the lower surface of the optical component and the upper surface of the substrate are brought closer to each other so that the light transmission parts can be brought closer to each other and the optical axis can be accurately aligned Therefore, it is particularly useful as a mounting structure for optical components in which optical components such as optical modules for optical communication and optical elements are mounted on a substrate.

Process explanatory drawing of the mounting method of the optical component of Embodiment 1 of this invention Sectional drawing of the mounting structure of the optical component of Embodiment 1 of this invention Sectional drawing of the optical component and board | substrate of Embodiment 1 of this invention Process explanatory drawing of the optical component mounting method of Embodiment 2 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A Optical component 2,5A Metal bump 3 1st light transmission part 4,4A Board | substrate 5,2A Connection electrode 6 2nd light transmission part 8 Resin adhesive material 8A Sealing resin part

Claims (1)

An optical component having a first light transmission portion and a first electrode provided on the lower surface is provided with a second light transmission portion that transmits and receives light to and from the first light transmission portion. A mounting structure of an optical component that is mounted on a substrate having a second electrode to which an electrode is bonded, wherein the first electrode is brought into contact with the second electrode and a load and ultrasonic vibration are applied to the optical component. Is applied to form a metal bonding surface in which the lower surface of the first electrode is metal bonded to the upper surface of the second electrode, and the height dimension of the first electrode or the second electrode in the mounting process Is reduced, the gap between the lower surface of the optical component and the upper surface of the substrate is smaller than that before mounting, and the first electrode and the second electrode are disposed around the joint portion of the first electrode. A light shielding resin layer that reinforces the joint between the electrode and the second electrode and shields light from the outside is formed. Mounting structure of an optical component, characterized in that there.

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