JP2009080451A - Flexible optoelectric interconnect and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible optoelectric interconnect which reduces thermal conduction from a driving IC to an optical semiconductor device with an inexpensive configuration. <P>SOLUTION: The flexible optoelectric interconnect includes: an optoelectric film having an electrical interconnect 4 for connecting semiconductor device, an optical waveguide core 3 and an optical waveguide clad 2; a driving IC 7 provided on the major surface of the optoelectric film and electrically connected to the electrical interconnect 4 for connecting the semiconductor device; an optical semiconductor device 6 provided on the major surface of the optoelectric film and driven by the driving IC 7; a heat dissipation plate 5 provided on the rear surface of the optoelectric film and covering the through hole such that at least a part of the through hole is protruded from an outer edge of the driving IC 7 extending from a major surface to a rear surface opposite to the major surface of the optoelectric film; and a thermally conductive resin 9 which is provided in the through hole and in contact with the driving IC 7 and the heat dissipation plate 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flexible photoelectric wiring and a method for manufacturing the same.

  Large-scale integrated circuits (LSIs) have been dramatically improved in operating speed by improving the performance of electronic devices such as bipolar transistors and field effect transistors. However, although the internal operation of the LSI has been accelerated, the operation speed at the level of the printed circuit board on which the LSI is mounted is kept lower than the operation speed of the LSI, and the operation speed is even lower at the rack level where the printed circuit board is mounted. It is suppressed.

  These are due to the increase in transmission loss, noise and electromagnetic interference of electrical wiring accompanying the increase in operating frequency, and it is necessary to lower the operating frequency for longer wiring in order not to degrade the signal quality. . Therefore, even if the operating speed of the LSI, which is an active element, is improved in the electrical wiring device, there is a problem that the speed of the mounting is inevitably reduced, and the mounting technology tends to dominate the system speed rather than the LSI operating speed. In recent years it has become stronger.

  In view of such problems of the electrical wiring device, several optical wiring devices for connecting LSIs with light have been proposed. The characteristics of the optical wiring device are that there is almost no frequency dependence such as loss in the frequency range from DC to 100 GHz or more, and there is no electromagnetic interference in the wiring path or ground potential fluctuation noise, so that wiring of several tens of Gbps can be easily realized. is there. For this reason, the optical wiring device can be expected to operate at a very high speed even at the printed circuit board or rack level.

In particular, the flexible type photoelectric composite wiring has a high degree of freedom for board mounting due to its flexibility, and the structure is simple because the electrode itself has the mounting electrodes of the optical elements (for example, Patent Documents). 1).
JP 2003-227951 A

  The present invention provides a flexible photoelectric wiring and a manufacturing method thereof that can reduce heat conduction from a driving IC to an optical semiconductor element with a low-cost structure.

  A flexible photoelectric wiring according to an aspect of the present invention includes a photoelectric film having a single-layered wiring layer, an optical wiring layer including an optical waveguide core and an optical waveguide cladding, and a main surface side of the photoelectric film. A driving IC provided and electrically connected to the electrical wiring layer; an optical semiconductor element provided on the main surface side of the photoelectric film; and driven by the driving IC; and a back surface side of the photoelectric film And a heat sink covering a through hole from the main surface to the back surface of the photoelectric film in a shape protruding at least partly from an outer edge of the drive IC, and filling the through hole, the drive IC And a heat conductive material in contact with the heat radiating plate.

  ADVANTAGE OF THE INVENTION According to this invention, the flexible photoelectric wiring which can reduce the heat conduction from a drive IC to an optical semiconductor element with a low-cost structure, and its manufacturing method can be provided.

[Comparative example]
In the flexible optoelectric wiring according to the prior art disclosed in Patent Document 1, not only can an optical element be mounted on itself, but also a driver IC (semiconductor chip) mounted on the optical element and these are electrically connected It can be. However, consideration for heat dissipation of the semiconductor chip is not sufficient, and a practical problem may occur.

  For example, when a method of dissipating heat by providing a thermal via at the lower part of a semiconductor chip, two or more electric wiring layers of the flexible substrate are required, and the cost is significantly increased as compared with a case where the electric wiring is a single layer. . Further, there arises a problem that the thermal resistance of the thermal via cannot be suppressed sufficiently low.

  Alternatively, as in the prior art disclosed in Patent Document 1, a method of applying heat dissipation by providing a through-hole having a size capable of including a semiconductor chip in an optoelectric film and embedding the semiconductor chip in the through-hole is applied. In addition, it is necessary to have a processing margin when punching the through hole with a mold, a positioning margin of the mold, and a semiconductor chip cutting processing margin. As a result, a through-hole size margin of at least several 100 μm, and in some cases, about several mm is required.

  Therefore, in the configuration according to the prior art, when a plurality of semiconductor chips are mounted in parallel, it is necessary to add an arrangement pitch margin of several hundred μm to several mm to the minimum arrangement pitch determined by the pattern arrangement of the electric wiring. That is, the conventional technology has a structural limit on the mounting density, and the construction of flexible optoelectric wiring having multi-parallel optical wiring is easy to increase in size.

  Furthermore, in the method of inserting through holes in a semiconductor chip as in the prior art and the method of forming a through hole in the outer range of the semiconductor chip, there is a problem in that yield tends to decrease in the process of curing the paste-like thermally conductive resin. Occurs.

  That is, in the method of inserting a through-hole in a semiconductor chip, a large amount of paste-like thermally conductive resin filled in the gap between the through-hole and the semiconductor chip may rise due to fluidization or distortion in the curing process. The problem of overflowing the connection pads of the chip and shorting the electrodes is likely to occur.

  This is due to the fact that the surface of the semiconductor chip and the paste-like thermally conductive resin surface are likely to be close to each other, and that the paste-like thermally conductive resin is likely to accumulate in the gap between the through holes on the side surface of the semiconductor chip due to capillary action.

  On the other hand, in the method of forming a through hole in the outer shape range of the semiconductor chip, the paste-like thermally conductive resin filled in the through hole in a large amount blocks the evaporation path of the solvent during the curing process. Is likely to be a problem. In this case, the mounting position shift or inclination of the semiconductor chip is caused. In severe cases, the semiconductor chip is inverted. Obviously, these all cause defects in subsequent processes.

  Further, since the photoelectric film has an optical waveguide inside, there is a problem that a certain thickness is inevitably required and heat dissipation is low. The optical element constituting the flexible opto-electrical wiring has a large characteristic variation due to heat compared to a semiconductor chip such as a driving IC, and it is important to secure a heat dissipation path of the semiconductor chip as a main heat source. Furthermore, it is assumed that the position of the optical waveguide core is shifted due to the large thermal expansion coefficient of the photoelectric film, resulting in poor coupling between the optical semiconductor element and the optical waveguide core. Therefore, securing the heat dissipation path of the drive IC and reducing the heat conduction from the drive IC to the optical element are important issues. In response to the above-mentioned problems found by the applicant, embodiments of the present invention will be described below with reference to the drawings.

[First embodiment]
FIG. 1 is a schematic perspective view showing a flexible photoelectric wiring according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the flexible optoelectric wiring according to the first embodiment of the present invention. FIG. 3 is a top view showing the flexible photoelectric wiring according to the first embodiment of the present invention. FIG. 1 to FIG. 3 show an optical transmitter (or optical receiver) and an electrical wiring part for connecting semiconductor elements. FIG. 4 is an overall view showing a schematic configuration of the flexible optoelectric wiring according to the first embodiment of the present invention.

  As shown in FIG. 4, the flexible photoelectric wiring according to the first embodiment includes a drive module unit 100 and a drive module unit 101. The drive module unit 100 and the drive module unit 101 contain an optical transmission unit, an optical reception unit, or both of them, and the optical transmission unit and the optical reception unit are paired via an optical waveguide. It fulfills its function. Hereinafter, the drive module unit 100 will be described in detail with reference to FIGS. 1 to 4, but the same description can naturally be applied to the drive module unit 101.

The drive module unit 100 includes a base film 1, an optical waveguide clad 2, an optical waveguide core 3, an electrical wiring 4 for connecting semiconductor elements, a heat sink 5, an optical semiconductor element 6 (light emitting element or light receiving element), a driving IC 7, an underfill. The resin 8, the heat conductive resin 9, the bonding wire 10, the mold resin 11, the bump metal 12, and the electric wiring 13 are included.

  The base film 1, the optical waveguide cladding 2, the optical waveguide core 3, the electrical wiring 4 for connecting the semiconductor elements, and the electrical wiring 13 constitute a flexible photoelectric film that can be freely bent. Hereinafter, the surface on which the semiconductor element connection electrical wiring 4 and the electrical wiring 13 are formed, the optical semiconductor element 6 and the driving IC 7 are provided is referred to as a main surface of the photoelectric film, and the surface on which the heat sink 5 is provided ( The surface opposite to the main surface) is referred to as the back surface of the photoelectric film.

  The base film 1 is made of, for example, a polyimide film having a thickness of 25 μm, and has an optical waveguide clad 2 on the back surface and an electric wiring layer to be described later on the surface.

  The optical waveguide cladding 2 and the optical waveguide core 3 are materials having different refractive indexes and transparent to the optical transmission wavelength, and these constitute an optical wiring layer. The optical waveguide cladding 2 and the optical waveguide core 3 are made of, for example, epoxy resin, and the refractive index of the optical waveguide core 3 is, for example, 1.59, and the refractive index of the optical waveguide cladding 2 is, for example, 1.56. As a result, an optical waveguide having an NA (Numerical Aperture) of about 0.3 is obtained.

  The optical waveguide core 3 is, for example, a rectangle having a cross section of 40 μm square, and the thickness of the optical waveguide cladding 2 around the optical waveguide core 3 is, for example, 15 μm in the optoelectric film main surface direction and in the optoelectric film back surface direction. It is formed to be 15 μm.

  The end of the optical waveguide core 3 is processed at 45 °, and a mirror metal (for example, Au) (not shown) is provided on the 45 ° processed surface. With this mirror metal, the input / output light of the optical semiconductor element 6 can be bent at 90 °, and optical transmission in the in-plane direction of the photoelectric film can be performed by the optical wiring layer (the optical waveguide cladding 2 and the optical waveguide core 3).

  The electrical wiring 4 for semiconductor element connection and the electrical wiring 13 are in the same electrical wiring layer and are collectively formed by patterning by photolithography. In this way, if the electrical wiring layer is a single layer, the patterning process is only required once, and the process such as via formation and through-hole plating required for a multilayer substrate of two or more layers is not required, which is very low. It can be manufactured at low cost. The electrical wiring 4 and the electrical wiring 13 for connecting the semiconductor elements are made of Cu having a thickness of 12 μm, for example, and the pad portion is subjected to Au / Ni plating. The semiconductor element connection electrical wiring 4 is used for electrical connection between the semiconductor elements such as the optical semiconductor element 6 and the driving IC 7, and the electrical wiring 13 is used for connection of a low speed signal or a power source between both ends of the photoelectric film.

  In the above-described optoelectric film, as shown in FIG. 2, a through-hole extending from the electric wiring layer to the optical wiring layer is formed below the mounting portion of the driving IC 7, that is, from the main surface side to the back surface side of the optoelectric film. Is provided. This through hole is provided so as to avoid the lower part of the portion that is wire-bonded to the drive IC 7.

  As shown in FIGS. 1 and 3, the through hole (inside of the broken line) is provided in a portion where the wire bonding of the drive IC 7 is not performed, and protrudes, for example, by about 0.5 to 1 mm from the outer edge (outer shape) of the drive IC 7 ( Projecting). The size of the portion where the through hole protrudes from the outer edge of the drive IC 7 may be determined in accordance with the width of the margin of the wiring pattern of the flexible photoelectric wiring, and is determined in consideration of the cross-sectional area of the heat radiation path and the thermal resistance. It ’s fine. Further, the shape of the through hole may be an overlap of two squares (cross shape) as shown in FIG.

  The heat radiating plate 5 is, for example, a Cu plate having a thickness of 500 μm, and at least an area larger than the mounting portion of the driving IC 7 is attached to the lower portion (optoelectric film back side) of the optical wiring layer. The heat radiating plate 5 covers a through hole formed in the lower part of the mounting portion of the driving IC 7. The heat generated from the drive IC 7 reaches the heat radiating plate 5 through a heat conductive resin 9 described later, and is released (heat radiated).

  In addition, the heat sink 5 reduces the heat conduction from the driving IC 7 to the optical semiconductor element 6 or from the driving IC 7 to the optical coupling portion at the end of the optical waveguide core 3. It is provided avoiding the direct under. The heat sink 5 also serves as a terminal treatment (reinforcing member) of the flexible photoelectric wiring. For example, the heat sink 5 and the end of the flexible photoelectric wiring together with the heat sink 5 can be inserted into and removed from the mounting board connector. .

  The optical semiconductor element 6 is a light-emitting element, a light-receiving element, or a composite element thereof, and is provided on the main surface side of the photoelectric film and controlled to emit or receive light by the drive IC 7. A light emitting element (for example, a surface emitting laser) may be used as the optical semiconductor element 6 in the optical transmitting unit, and a light receiving element (for example, a surface receiving photodiode) may be used as the optical semiconductor element 6 in the optical receiving unit. In the case of performing bidirectional optical transmission, an element in which both the light emitting element and the light receiving element are integrated into one chip may be used. In addition, the optical semiconductor element 6 is a light emitting element. When transmitting light, the light emitting element is forward biased to emit light, and when receiving light, the light emitting element is reverse biased and used as a light receiving element. Transmission). The optical semiconductor element 6 and the electrical wiring 4 are connected via a bump metal 12. The bump metal 12 is, for example, an Au stud bump, a solder bump, or the like. For example, an epoxy resin is applied as the insulating underfill resin 8 around the bump connection portion.

  The drive IC 7 is fixed on the heat conductive resin 9 filled in the through hole described above. The drive IC 7 is a driver IC that is used for an optical transmission unit and emits a light emitting element based on an external input electric signal, and a receiver IC that is used for an optical reception unit and reproduces an external output electric signal from the photocurrent of the light receiving element. . In the case of the optical half-duplex transmission described above, a driver / receiver combined function IC may be used as the driver IC 7. In addition, the drive IC 7 may have an operation control function for stopping the optical transmission / reception operation by cutting off the drive bias of the optical semiconductor element 6 regardless of the presence or absence of an external electric signal or an optical signal.

  The thermally conductive resin 9 is a material having a higher thermal conductivity than the photoelectric film (excluding the electrical wiring layer), for example, a hardened Ag paste, filling the through holes formed in the photoelectric film. The space surrounded by the heat sink 5 and the drive IC 7 is filled. Further, the heat conductive resin 9 is thinly applied also to a portion where the drive IC 7 is mounted. The driving IC 7 is mounted such that the circuit surface faces upward (in a direction not facing the optoelectric film), and the surface opposite to the circuit surface is in contact with the heat conductive resin 9.

  A bonding wire 10 (for example, an Au wire or an Al wire) electrically connects the semiconductor element connection electric wiring 4 and the drive IC 7. In the first embodiment, since the circuit surface of the drive IC 7 faces upward, the connection to the electric wiring layer is established by wire bond connection.

  The mold resin 11 molds the entire semiconductor element mounting portion including the optical semiconductor element 6 and the driving IC 7 described above. The mold resin 11 shown in FIG. 4 includes a transmitter / receiver of flexible photoelectric wiring as shown in FIGS.

  According to the flexible optoelectric wiring having the above-described configuration, a heat radiation path to the back surface of the optoelectric film can be effectively ensured even if the electrical wiring 4 for connecting the semiconductor elements and the electrical wiring 13 have an inexpensive single layer configuration. In addition, it is possible to ensure a heat dissipation path cross-sectional area larger than the chip area of the drive IC 7, and the heat dissipation effect is higher than when a through hole having the same size as the chip area of the drive IC 7 is provided. That is, heat radiation of the driving IC 7 is performed through a through hole formed in the photoelectric film, and the shape of the through hole is formed so as to partially protrude from the outer edge of the driving IC 7, thereby improving the heat radiation property, It reduces heat conduction.

  When a method of dissipating heat by embedding a semiconductor chip in the optoelectric film and embedding the semiconductor chip in the through hole as in the comparative example is applied, when punching the through hole with a mold Machining margin and die alignment margin, and further, a semiconductor chip cutting margin is required.

  On the other hand, according to the flexible optoelectronic wiring according to the first embodiment, since the periphery of the drive IC 7 is a free space, even if the through hole is formed by punching the die, the external error of the drive IC 7 and the penetration Pore size error is unlikely to be a fatal problem. Moreover, since the positional deviation of the through hole, which is the only problem, is as small as several tens of micrometers, the size margin of the through hole can be as small as several tens of micrometers. For this reason, even when a plurality of driving ICs are mounted in parallel, it is possible to perform high-density parallel mounting of driving ICs with a minimum arrangement pitch substantially as a pattern arrangement of electric wiring.

  Further, the heat radiating plate 5 is provided so as to avoid being directly below the optical semiconductor element 6 in the in-plane direction of the photoelectric film, thereby reducing heat conduction from the driving IC 7 to the optical semiconductor element 6. Coupling failure with the optical waveguide core 3 can be suppressed. This makes it possible to operate the optical semiconductor element 6 stably without being affected by temperature fluctuations of the driving IC 7 and to improve reliability.

Next, the manufacturing process of the flexible optoelectric wiring shown in FIGS. 1 to 4 will be described.

  First, for example, an optical waveguide clad 2 and an optical waveguide core made of a material such as an epoxy resin are formed on the back surface (surface without Cu foil) of a base film 1 (for example, a polyimide film having a thickness of 25 μm) bonded with a 12 μm thick Cu foil. 3 is formed. For this purpose, for example, the base clad layer and the core layer film are laminated, the optical waveguide core 3 is patterned by photolithography, and the upper clad layer film is laminated. Each resin layer may be formed by spin coating of liquid resin and heat treatment. The refractive index of the optical waveguide core 3 is, for example, 1.59, and the refractive index of the optical waveguide cladding 2 is, for example, 1.56.

  Next, as shown in FIG. 2, the end portion of the optical waveguide core 3 is processed at 45 °, and a mirror metal (for example, Au) is provided on the 45 ° processed surface. For example, dicing or excimer laser processing can be used for 45 ° processing of the end portion of the optical waveguide core 3. The mirror metal is formed, for example, by selective vapor deposition (resistance heating, sputtering, etc.) using a metal mask.

  Next, the portions other than the electrical connection pads (not shown) are covered with, for example, a 30 μm thick solder resist, and Au / Ni plating is applied to the pad portions. The bump metal 12 is, for example, an Au stud bump, and the optical semiconductor element 6 is connected to the electric wiring 4 by thermocompression bonding or ultrasonic connection. This may be a method in which the bump metal 12 is used as a solder bump and heated and melted.

  Next, underfill resin 8 (for example, epoxy resin) is applied around the bump connection portion, and is reinforced by performing a curing process (heating, UV irradiation, etc.).

  Next, as shown in FIG. 2, a through hole (a portion filled with the heat conductive resin 9) penetrating from the electric wiring layer to the optical wiring layer is provided in the lower portion of the mounting portion of the driving IC 7. For this, a method such as punching with a die may be used, and the processing cost is very low. As shown in FIG. 2, the through hole is provided so as to avoid the lower portion of the portion that is wire-bonded to the drive IC 7. This is to ensure strength when wire bonding is performed. Further, as shown in FIGS. 1 and 3, the through-hole (inside the broken line) is a portion where the wire bonding of the drive IC 7 is not performed, and protrudes from the outer edge of the drive IC 7 by about 0.5 to 1 mm, for example. Form into shape.

  Next, the heat radiating plate 5 having an area larger than at least the mounting portion of the driving IC 7 is attached to the lower part (back side of the photoelectric film) of the optical wiring layer. The heat radiating plate 5 is, for example, a Cu plate having a thickness of 500 μm.

  Next, the heat conductive resin 9 (for example, Ag paste) is filled in the through hole in a paste state, and is applied thinly to the portion where the drive IC 7 is mounted, and the drive IC 7 is mounted. Then, the drive IC 7 is fixed by performing a curing process (heating, UV irradiation, etc.) of the heat conductive resin 9.

  Next, the semiconductor element connection electrical wiring 4 and the drive IC 7 are electrically connected by a bonding wire 10 (for example, Au wire or Al wire), and the entire semiconductor element mounting portion is sealed with the mold resin 11.

The flexible optoelectric wiring shown in FIGS. 1 to 4 is obtained through the above steps.

  As in the comparative example described above, the method of inserting through holes in a semiconductor chip and the method of forming a through hole in the outer shape range of a semiconductor chip tend to cause a decrease in yield in the step of curing the paste-like thermally conductive resin. Problems arise.

  On the other hand, in the flexible optoelectronic wiring according to the first embodiment, since the paste-like heat conductive resin 9 is located below the semiconductor chip such as the drive IC 7, the paste-like heat conductive resin is used in the curing process. 9 is unlikely to be a problem, and since the through hole is provided with a portion protruding beyond the outer edge of the semiconductor chip such as the drive IC 7, the drive IC 7 is lifted by the ejection of the solvent in the curing process. Can be prevented.

  As described above, according to the flexible photoelectric wiring and the manufacturing method thereof according to the first embodiment, it is possible to obtain a high heat dissipation performance while using a low-cost single-layer electrical wiring, and it is also possible to reduce the mounting density and manufacture. A decrease in yield can be suppressed to a minimum, and a high-performance flexible optoelectronic wiring can be obtained at low cost.

  Therefore, according to the present invention, the optical wiring of the mounting board can be realized at a low cost, and it is possible to contribute to the advancement of information communication equipment and the like by promoting the high speed and high performance of the mounting board.

[Second Embodiment]
FIG. 5 is a schematic perspective view showing a flexible optoelectric wiring according to the second embodiment of the present invention. FIG. 6 is a cross-sectional view showing a flexible optoelectric wiring according to the second embodiment of the present invention. FIG. 7 is a top view showing a flexible optoelectric wiring according to the second embodiment of the present invention. 5 to 7, the optical transmitter (or the optical receiver) and the electrical wiring part for connecting the semiconductor elements are extracted and shown, and the schematic overall configuration is the same as that shown in FIG.

  Note that components substantially the same as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In the second embodiment, the drive IC 7 is electrically connected by so-called flip chip connection instead of wire bond connection, and the heat dissipation direction of the drive IC 7 is the chip surface direction (circuit surface direction). It is.

  In the case of flip-chip connection, the mold resin 11 is not always necessary and is not used here as shown in FIGS. On the other hand, the flip chip connection requires that a heat conductive resin (usually a conductive resin such as Ag paste) be brought into contact with the circuit surface of the drive IC 7 for heat dissipation. If it comes in contact with metal, there is a problem that it simply shorts out and does not function.

  The simplest solution is to use a material that has both insulating properties and thermal conductivity. However, resins that achieve both of these characteristics can be used for those with high dielectric loss and poor high-frequency characteristics, At present, there are many cases where the protective function of the metal bump bonding portion is not satisfied. For this reason, in the second embodiment, it is necessary to devise the configuration and the manufacturing method, and it is desirable to configure and manufacture as follows.

The flexible optoelectronic wiring according to the second embodiment includes a base film 1, an optical waveguide cladding 2, an optical waveguide core 3, an electrical wiring 4 for connecting semiconductor elements, a heat sink 5, and an optical semiconductor element 6 (light emitting element or light receiving element). ), Driving IC 7, underfill resin 8, thermally conductive resin 9, and bump metal 12.

  An insulating underfill resin 8 is filled around the bump metal 12 that connects the optical semiconductor element 6 and the driving IC 7 to the electric wiring 4 for connecting the semiconductor element, and the electrical connection portion is protected and insulated. On the other hand, a through-hole formed in the lower portion of the drive IC 7 (the same shape as in the first embodiment) is filled with a heat conductive resin 9 made of a material different from the underfill resin 8. A heat conductive resin (conductive resin) 9 is in contact with the circuit surface.

  In the flexible optoelectronic wiring according to the second embodiment, heat dissipation of the flip-chip connected drive ICs 7 is realized by using a composite of resin whose reliability and performance have been confirmed. That is, the bump metal 12 and the connection pad portion selectively form the underfill resin 8, and heat is applied to the through holes formed under the remaining portion of the drive IC 7 (the portion where the underfill resin 8 is not in contact). The conductive resin 9 is filled to achieve both insulation and heat dissipation.

  According to the flexible optoelectric wiring according to the second embodiment, in addition to the same effect as that of the first embodiment, an effect that heat can be radiated from the chip surface (circuit surface of the drive IC 7) that generates a large amount of heat can be obtained. Accordingly, it is possible to further reduce the heat conduction from the driving IC 7 to the optical semiconductor element 6. In addition, since the electrical connection between the optical semiconductor element 6 and the driving IC 7 can be performed with the shortest distance, the operation speed can be easily improved.

  Moreover, the through-hole formed similarly to 1st Embodiment plays an important role in the manufacturing method of the flexible photoelectric wiring which concerns on 2nd Embodiment. Hereinafter, the manufacturing process of the flexible optoelectric wiring shown in FIGS. 1 to 4 will be described, and the reason why the through hole plays an important role will be described.

  First, the optical waveguide clad 2 and the optical waveguide core 3 are formed on the base film 1 bonded with Cu foil as in the first embodiment. Next, the electrical wiring 4 for semiconductor element connection and the electrical wiring 13 are formed, and a photoelectric film is obtained.

  Next, a through-hole is provided in a shape that avoids the electrical connection pad portion of the photoelectric film and partially protrudes from the outer edge of the drive IC 7. Next, the heat sink 5 is bonded to the lower part of the optical wiring layer, and the optical semiconductor element 6 and the driving IC 7 are flip-chip connected using the bump metal 12. At this time, the bump metal 12 is, for example, an Au stud bump, and is connected to the electric wiring 4 for semiconductor element connection by thermocompression bonding or ultrasonic connection. Alternatively, the bump metal 12 may be a solder bump and may be heated and fused.

  Next, the underfill resin 8 is injected into the sides of the optical semiconductor element 6 and the driving IC 7. At this time, by appropriately controlling the injection amount of the underfill resin 8, the injection of the underfill resin 8 into the region where the driving IC 7 and the optoelectric film face each other is automatically stopped at the boundary of the through hole. Can do.

  That is, the gap between the driving IC 7 and the photoelectric film becomes a discontinuous portion at the periphery of the through hole, and becomes a stop boundary of the capillary phenomenon. However, when an extremely large amount of the underfill resin 8 is injected, the underfill resin 8 may flow into the through hole from the boundary of the through hole due to the pressure of the resin. However, this is a case of a considerably extreme amount of resin, and it can be considered that the resin substantially stops at the boundary of the through hole.

  Next, the underfill resin 8 is heat-treated, and the solvent is evaporated to be cured. At this time, the heat treatment is performed with sufficient ventilation so that the resin solvent does not remain. Next, the thermal conductive resin 9 is injected from the through hole opening on the side surface of the chip.

  According to the above-described flexible optoelectric wiring manufacturing method, the through hole is formed so as to protrude beyond the outer edge of the drive IC 7, and the protruding through hole functions as an injection window for the heat conductive resin 9. Injection can be performed smoothly.

  Further, since the electrical connection portions of the optical semiconductor element 6 and the driving IC 7 are insulated by the underfill resin 8, even if the heat conductive resin (generally conductive resin) slightly overflows from the opposite side of the through hole, the driving IC 7 There are few problems such as short circuit of electrical terminals. Rather, it is possible to inject a large amount of the heat conductive resin so that bubbles are not included in the lower part of the driving IC 7.

[Modification]
The present invention is not limited to the first embodiment and the second embodiment described above, and various modifications can be made without departing from the scope of the invention in the implementation stage. For example, although polyimide resin is shown as the above-mentioned base film, other materials such as urethane resin and acrylic resin may be used depending on the application, and epoxy resin is shown as the optical waveguide material. Other materials such as polyimide resin, silicone resin, and acrylic resin can also be used. That is, these are merely exemplary configurations, and other means (materials, dimensions, etc.) may be used for individual elements in accordance with the gist of the present invention. It is also possible to implement the embodiments in combination. In addition, the present invention can be variously modified and implemented without departing from the spirit of the present invention.

  Further, the first embodiment and the second embodiment include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the present embodiment, at least one of the problems described in the column of the problem to be solved by the invention can be solved, and described in the column of the effect of the invention. In a case where at least one of the obtained effects can be obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention.

The perspective view of the flexible optoelectric wiring which concerns on 1st Embodiment. Sectional drawing of the flexible optoelectric wiring which concerns on 1st Embodiment. The top view of the flexible optoelectric wiring which concerns on 1st Embodiment. 1 is an overall view of a flexible optoelectric wiring according to a first embodiment. The perspective view of the flexible optoelectric wiring which concerns on 2nd Embodiment. Sectional drawing of the flexible optoelectric wiring which concerns on 2nd Embodiment. The top view of the flexible optoelectric wiring which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base film 2 Optical waveguide clad 3 Optical waveguide core 4 Electric wiring for semiconductor element connection 5 Heat sink 6 Optical semiconductor element 7 Drive IC
8 Underfill resin 9 Thermal conductive resin 10 Bonding wire 11 Mold resin 12 Bump metal 13 Electrical wiring

Claims (5)

A photoelectric film having a single-layer electrical wiring layer and an optical wiring layer including an optical waveguide core and an optical waveguide cladding;
A driving IC provided on the main surface side of the photoelectric film and electrically connected to the electrical wiring layer;
An optical semiconductor element provided on the main surface side of the photoelectric film and driven by the driving IC;
A heat sink that is provided on the back surface side of the photoelectric film and covers a through-hole extending from the main surface side to the back surface side of the photoelectric film in a shape protruding at least partly from an outer edge of the drive IC,
A flexible optoelectric wiring comprising: a heat conductive material filled in the through hole and in contact with the driving IC and the heat radiating plate.   The electrical wiring layer and the drive IC have an electrical connection part to which wire bonding is connected, and the thermal conductive material is in contact with a surface opposite to the circuit surface of the drive IC. The flexible optoelectric wiring according to 1.   An electrical connection portion where the electrical wiring layer and the drive IC are flip-chip connected; and an insulating underfill resin filled in the electrical connection portion, wherein the heat conductive material is a circuit surface of the drive IC. The flexible optoelectric wiring according to claim 1, wherein the flexible optoelectric wiring is in contact with the wiring. In the manufacturing method of the flexible optoelectronic wiring according to claim 2,
Injecting the thermally conductive material into the through hole in a paste state;
Mounting the driving IC such that the surface opposite to the circuit surface is in contact with the heat conducting material;
Curing the thermally conductive material in a paste state;
A method of manufacturing a flexible opto-electrical wiring, comprising the step of performing electrical connection between the driving IC and the electrical wiring layer to form an electrical connection part. In the manufacturing method of the flexible optoelectronic wiring according to claim 3,
Performing flip chip connection between the drive IC and the electrical wiring layer to form an electrical connection portion;
Injecting underfill resin in the vicinity of the electrical connection part;
Curing the underfill resin;
After the step of curing the underfill resin, a step of injecting the thermally conductive material into the through hole in a paste state;
And a step of curing the heat conductive material in a paste state.

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