JP7372754B2 - Optical/electrical hybrid board - Google Patents

Description

The present invention relates to an opto-electrical hybrid board.

2. Description of the Related Art Conventionally, an opto-electrical hybrid board is known that includes an optical waveguide made of resin and an electric circuit board in order in the thickness direction (see, for example, Patent Document 1 below).

In the opto-electric hybrid board described in Patent Document 1, the electric circuit board includes an external terminal for electrically connecting to a terminal of an external board.

Japanese Patent Application Publication No. 2018-151570

However, there are various methods of connecting the external terminals and the terminals of the external board. For example, one method is to place solder between them and then apply ultrasonic waves to the solder to melt the solder (1). There is.

In addition, an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP) is placed between the external terminal and the terminal of the external board, and then the external terminal and the ACF or ACP are placed between the external terminal and the terminal of the external board. , a method (2) of thermocompression bonding with a terminal. Note that ACF or ACP contains conductive particles, and exhibits conductivity in the thickness direction by thermocompression bonding in the thickness direction.

However, in method (1), since the optical waveguide is made of resin and is relatively flexible, the ultrasonic wave escapes to the optical waveguide via the external terminal (is diffused in the optical waveguide). Therefore, the solder is not sufficiently melted, and as a result, there is a problem that the reliability of electrical connection between the external terminal and the terminal of the external board is reduced.

On the other hand, in method (1), if the output of the ultrasonic waves is increased so that the solder is completely melted, the opto-electrical hybrid board will be damaged. Specifically, the optical waveguide may peel off from the electrical circuit board, or the optical waveguide may peel off from the electrical circuit board. The transmission loss of the wave path may increase. Furthermore, there is a problem in that the optical elements connected to the opto-electrical hybrid board are damaged.

Furthermore, in method (2), since the optical waveguide is flexible, heat and pressure during thermocompression bonding escape to the optical waveguide. Therefore, in ACF or ACP, the conductive particles are not oriented in the thickness direction, and as a result, there is a problem that the reliability of electrical connection between the external terminal and the terminal of the external substrate is reduced.

On the other hand, in method (2), if the heating temperature and pressure for thermocompression bonding are increased so that the conductive particles are sufficiently oriented in the thickness direction, the opto-electrical hybrid board will be damaged, and furthermore, the optical element will be damaged. There is a problem.

The present invention provides an opto-electric hybrid board that can suppress damage to the opto-electric hybrid board and optical elements mounted thereon, and has excellent electrical connection reliability with a printed wiring board.

The present invention (1) comprises an optical waveguide and an electric circuit board in order toward one side in the thickness direction, the electric circuit board includes a terminal for electrically connecting to a printed wiring board, and the terminal It includes an opto-electrical hybrid board that is misaligned with the optical waveguide when projected in the thickness direction.

In this opto-electric hybrid board, the terminals are out of alignment with the optical waveguides when projected in the thickness direction. In other words, the terminal does not overlap the optical waveguide.

Therefore, method (1) of mounting a printed wiring board on an opto-electrical hybrid board using ultrasonic waves prevents the ultrasonic waves from escaping into the optical waveguide and connects the terminals with the terminals of the printed wiring board. can be connected reliably. Further, since the above-described effects are achieved, it is possible to use ultrasonic waves of normal output, so damage to the opto-electrical hybrid board and the optical elements mounted thereon can be suppressed.

In addition, if the method (2) is to mount the printed wiring board on the opto-electrical hybrid board by thermocompression bonding of ACF or ACP, it is possible to connect the terminals and the printed wiring board while suppressing the escape of such heat and pressure to the optical waveguide. Terminals can be connected reliably. In addition, since the above-described effects are achieved, the terminals can be thermocompression bonded at normal heating temperatures and pressures, so damage to the opto-electrical hybrid board and the optical elements mounted thereon can be suppressed.

Therefore, with this opto-electric hybrid board, it is possible to electrically connect the terminals and the terminals of the printed wiring board with excellent connection reliability while suppressing damage to the opto-electric hybrid board and the optical elements mounted thereon. I can do it.

In the present invention (2), the optical waveguide is arranged on the inner side of the electric circuit board in the orthogonal direction that is orthogonal to the thickness direction and the transmission direction in a cross-sectional view along the orthogonal direction that is orthogonal to the thickness direction and the transmission direction. The opto-electrical hybrid board described in (1) is arranged.

In this opto-electric hybrid board, since the optical waveguide is arranged inside the electric circuit board in cross-sectional view, warpage can be reduced.

The present invention (3) is based on (1) or (2), wherein the percentage of the area of the overlapping portion of the optical waveguide and the electric circuit board with respect to the area of the electric circuit board is 5% or more and 50% or less. This includes the opto-electrical hybrid board described above.

In this opto-electrical hybrid board, since the percentage of the area of the overlapping portion of the optical waveguide and the electric circuit board is 50% or less, warpage of the opto-electric hybrid board can be suppressed, and as a result, the optical waveguide from the electric circuit board can be suppressed. Peeling can also be suppressed. On the other hand, since the percentage of the area of the overlapping portion of the optical waveguide and the electric circuit board is 5% or more, the degree of freedom in the arrangement of the optical waveguide can be ensured, and the optical transmission characteristics of the opto-electrical hybrid board can be ensured.

In the present invention (4), the electric circuit board includes a metal support layer, a base insulating layer, and the terminal in order toward one side in the thickness direction, and the metal support layer and the base The opto-electrical hybrid board according to any one of (1) to (3), wherein the area percentage of the overlapping portion of the insulating layers is 5% or more and 50% or less.

In this opto-electrical hybrid board, since the percentage of the area of the overlapping portion of the metal support layer and the base insulating layer is 50% or less, warping caused by the characteristics of the metal support layer can be suppressed, and as a result, the electric circuit board Peeling of the optical waveguide from the substrate can also be suppressed. Since the area percentage of the overlapping portion of the metal support layer and the base insulating layer is 5% or more, the degree of freedom in arrangement of the metal support layer can be ensured.

In the present invention (5), a plurality of the terminals are arranged at intervals in an orthogonal direction perpendicular to the thickness direction and the transmission direction, and the plurality of terminals connect the central portion of the optical waveguide in the orthogonal direction to the transmission direction. The opto-electrical hybrid board according to any one of (1) to (4) is arranged symmetrically with respect to a center line passing along the direction.

In this opto-electrical hybrid board, since the plurality of terminals are arranged symmetrically with respect to the center line of the optical waveguide, warpage of the opto-electric hybrid board in the orthogonal direction can be reduced.

According to the opto-electrical hybrid board of the present invention, it is possible to suppress damage to the opto-electric hybrid board and the optical elements mounted thereon, while electrically connecting the terminal and the terminal of the printed wiring board with excellent connection reliability. can do.

FIG. 1 shows a plan view of an embodiment of the opto-electrical hybrid board of the present invention. FIG. 2 shows a side sectional view of the opto-electrical hybrid board shown in FIG. 1 along the line XX. FIG. 3 shows a front cross-sectional view of the opto-electrical hybrid board shown in FIG. 1 along the YY line. FIG. 4 shows a plan view of an embodiment in which an optical element and a printed wiring board are mounted on the opto-electrical hybrid board shown in FIG. FIG. 5 shows a modification of the opto-electric hybrid board shown in FIG. 3 (a modification in which the entire lower surface of the base insulating layer is disposed on the upper surface of the metal support layer). FIG. 6 shows a modification of the opto-electrical hybrid board shown in FIG. 3 (a modification in which optical waveguides are arranged at both ends in the width direction of the electric circuit board). FIG. 7 shows a further modification of the opto-electrical hybrid board shown in FIG. A modified example in which the circuit board protrudes from the circuit board to the other side in the width direction is shown. FIG. 8 shows a modification of the opto-electrical hybrid board shown in FIG. 3 (a modification in which an opening is formed in the region facing the first terminal of the optical waveguide). FIG. 9 shows a modification of the opto-electrical hybrid board shown in FIG. 3 (a modification in which the plurality of first terminals are arranged asymmetrically with respect to the center line of the optical waveguide). FIG. 10 shows a front cross-sectional view of the opto-electric hybrid board of Comparative Example 1.

An embodiment of the opto-electrical hybrid board of the present invention will be described with reference to FIGS. 1 to 4.

The opto-electrical hybrid board 1 has a substantially sheet shape extending in a longitudinal direction (an example of a light transmission direction). The opto-electric hybrid board 1 includes an optical waveguide 2 and an electric circuit board 3 in order toward the upper side (an example of one side in the thickness direction).

The optical waveguide 2 is located in the lower part of the opto-electrical hybrid board 1. The optical waveguide 2 has a substantially sheet shape extending in the longitudinal direction. Further, the outer shape of the optical waveguide 2 is included in the outer shape of the opto-electrical hybrid board 1 in plan view, and specifically, it is smaller than the electric circuit board 3 described below. As shown in FIG. 3, the optical waveguide 2 is arranged at a widthwise intermediate portion (specifically, approximately at the center) of the opto-electrical hybrid board 1. As shown in FIG. Further, a center line CL passing through the center in the width direction of the optical waveguide 2 and along the longitudinal direction coincides with a center line passing through the center in the width direction of the opto-electric hybrid board 1 and along the longitudinal direction.

The optical waveguide 2 includes an underclad layer 4, a core layer 5, and an overclad layer 6 in this order toward the lower side (an example of the other side in the thickness direction).

The peripheral surface of the core layer 5 in a front cross-sectional view is covered with an under cladding layer 4 and an over cladding layer 6. Note that the core layer 5 includes a plurality of core parts 23. A plurality of core portions 23 are arranged in plurality (three) at intervals in the width direction (an example of a direction orthogonal to the thickness direction and the light transmission direction). Each of the plurality of core parts 23 extends along the longitudinal direction. A mirror 7 is formed at one longitudinal end of each of the plurality of core parts 23 . Examples of the material for the optical waveguide 2 include transparent materials such as epoxy resin, acrylic resin, and silicone resin. Preferably, from the viewpoint of optical signal transmission properties, epoxy resin is used.

The electric circuit board 3 is placed above the optical waveguide 2 . The electric circuit board 3 has a substantially plate shape extending in the longitudinal direction. The electric circuit board 3 forms the outer shape of the opto-electric hybrid board 1 in a plan view. That is, in plan view, the external shape of the electric circuit board 3 is the same as the external shape of the opto-electrical hybrid board 1.

Further, as shown in FIG. 3, in a cross-sectional view along the width direction, both ends of the electric circuit board 3 in the width direction are arranged on both sides of the optical waveguide 2 in the width direction. Specifically, both end portions of the electric circuit board 3 in the width direction protrude from both end surfaces of the optical waveguide 2 in the width direction to the outside in the width direction. In other words, the optical waveguide 2 is located (close to) the widthwise inner side of both widthwise end surfaces of the electric circuit board 3 (unevenly distributed inwardly) in a cross-sectional view along the widthwise direction.

Further, as shown in FIG. 2, one end of the electric circuit board 3 in the longitudinal direction is arranged on one side of the optical waveguide 2 in the longitudinal direction in a cross-sectional view along the longitudinal direction. Specifically, one end in the longitudinal direction of the electric circuit board 3 protrudes from one end surface in the longitudinal direction of the optical waveguide 2 to one side in the longitudinal direction. In other words, the optical waveguide 2 is located on the other longitudinal side of one longitudinal end of the electric circuit board 3 (retracted) in a cross-sectional view along the longitudinal direction.

The electric circuit board 3 includes a metal support layer 8, a base insulating layer 9, and a conductor layer 10 in this order toward the top. The metal support layer 8 is formed in a region corresponding to a second terminal 12 (described later). On the other hand, as shown in FIG. 3, the metal support layer 8 has a slightly larger size than the optical waveguide 2 in a cross-sectional view along the width direction. Examples of the material of the metal support layer 8 include metal materials such as stainless steel.

Base insulating layer 9 has the same planar shape as electric circuit board 3 . The base insulating layer 9 includes the metal support layer 8 when projected in the vertical direction, and specifically, in a cross-sectional view along the width direction, each of the widthwise both ends of the base insulating layer 9 is The metal support layer 8 protrudes from both ends of the metal support layer 8 to the outer sides in the width direction.

Examples of the material for the base insulating layer 9 include insulating materials such as polyimide.

The conductor layer 10 includes a first terminal 11, a second terminal 12, which are examples of terminals, and wiring (not shown).

The first terminal 11 is a terminal for electrical connection to a printed wiring board (PCB) 15. A plurality of first terminals 11 are arranged at one longitudinal end of the opto-electrical hybrid board 1 . Specifically, the plurality of first terminals 11 are arranged at one end in the longitudinal direction in a PCB mounting bonding area 16 (see FIG. 4), which will be described later. In plan view, the plurality of first terminals 11 are arranged in a substantially U-shape so as to surround a plurality of second terminals 12 (not shown in FIG. 1), which will be described next.

As shown in FIG. 4, the PCB mounting bonding area 16 is an area that overlaps a printed wiring board 15, which will be described later, in a plan view, and has a substantially U-shape that opens toward the other side in the longitudinal direction. area. Note that the PCB mounting joint area 16 includes two longitudinal areas 17 that extend in the longitudinal direction and are spaced apart from each other in the width direction, and a connection area 18 that connects one end of the two longitudinal areas 17 in the longitudinal direction. In each of the two longitudinal areas 17 and the connection area 18, a plurality of first terminals 11 are arranged in alignment at intervals from each other.

Further, the first terminal 11 is arranged symmetrically with respect to the center line CL of the optical waveguide 2.

Examples of the material for the conductor layer 10 include conductor materials such as copper.

The percentage of the area of the overlapping portion of the optical waveguide 2 and the electric circuit board 3 with respect to the area of the electric circuit board 3 (synonymous with the planar area; the same applies hereinafter) is, for example, 50% or less, and, for example, 1% or more. , preferably 5% or more. In addition, in FIG. 3, the overlapping portion of the optical waveguide 2 and the electric circuit board 3 is shown as a first region OL1.

If the percentage of the area of the overlapping portion of the optical waveguide 2 and the electric circuit board 3 is below the above-mentioned upper limit, warping of the opto-electrical hybrid board 1 can be suppressed, and as a result, the optical waveguide 2 from the electric circuit board 3 can be prevented from warping. Peeling can also be suppressed. On the other hand, if the above-mentioned area percentage is equal to or larger than the above-mentioned lower limit, the degree of freedom in the arrangement of the optical waveguide 2 can be ensured, and the optical transmission characteristics in the opto-electrical hybrid board 1 can be ensured.

Further, the percentage of the area of the overlapping portion of the metal support layer 8 and the base insulating layer 9 with respect to the area of the metal support layer 8 is, for example, 50% or less, and is, for example, 1% or more, preferably 5% or more. It is. Note that in FIG. 3, the overlapping portion of the metal support layer 8 and the base insulating layer 9 is shown as a second region OL2.

Note that the first region OL1 is narrower than the second region OL2.

If the percentage of the area of the overlapping portion of the metal support layer 8 and the base insulating layer 9 is below the above-mentioned upper limit, it is possible to suppress warpage caused by the spring characteristics of the metal support layer 8, and as a result, the electric circuit board 3 Peeling of the optical waveguide 2 from the surface can also be suppressed. On the other hand, if the percentage of the area of the overlapping portion of the metal support layer 8 and the base insulating layer 9 is equal to or larger than the above-mentioned lower limit, the degree of freedom in the arrangement of the metal support layer 8 can be ensured.

As shown in FIGS. 1 to 3, this first terminal 11 is shifted from the optical waveguide 2 when projected in the vertical direction. That is, the first terminal 11 does not overlap the optical waveguide 2 when projected in the vertical direction. In other words, the optical waveguide 2 is not arranged below the first terminal 11.

Specifically, as shown in FIGS. 1 and 3, the first terminals 11 in the longitudinal area 17 are arranged at intervals on both outer sides of the optical waveguide 2 in a cross-sectional view along the width direction. Specifically, the first terminals 11 in the longitudinal area 17 are spaced apart from each other on both outer sides of both end faces in the width direction of the optical waveguide 2 .

Further, as shown in FIGS. 1 and 2, the first terminals 11 of the connection area 18 are arranged at intervals on one side in the longitudinal direction of the optical waveguide 2 in a cross-sectional view along the longitudinal direction. Specifically, the first terminals 11 of the connection area 18 are spaced apart from each other on one longitudinal side of one longitudinal end surface of the optical waveguide 2 .

Specifically, one end in the longitudinal direction of the optical waveguide 2 is disposed within the inner region 13 surrounded by the PCB mounting bonding area 16 which is approximately U-shaped in plan view. That is, in a cross-sectional view along the width direction, the two longitudinal areas 17 are arranged apart from each other on both sides of the optical waveguide 2 in the width direction. Furthermore, in a cross-sectional view along the longitudinal direction, the connection areas 18 are arranged at one side in the longitudinal direction of the optical waveguide 2 .

The amount of deviation between the first terminal 11 and the optical waveguide 2 in plan view is defined as the shortest distance.

As shown in FIG. 2, the second terminal 12 is a terminal for electrically connecting to the optical element 14. A plurality of second terminals 12 are arranged at the center of one longitudinal end of the electric circuit board 3 in plan view. The plurality of second terminals 12 are spaced from the first terminal 11. The plurality of second terminals 12 are arranged at intervals in the longitudinal direction and the width direction. Note that the plurality of second terminals 12 overlap the optical waveguide 2 when projected in the vertical direction.

Wiring (not shown) electrically connects each of the plurality of first terminals 11 and each of the plurality of second terminals 12.

Although not shown, the electric circuit board 3 may include a cover insulating layer covering wiring (not shown) on the upper surface of the base insulating layer 9.

This opto-electrical hybrid board 1 is obtained by a known method; for example, first, an electric circuit board 3 is manufactured, and then an optical waveguide 2 is formed on the lower surface of the electric circuit board 3.

Next, a method for mounting optical element 14 and printed wiring board 15 on opto-electrical hybrid board 1 will be explained.

First, the opto-electric hybrid board 1, the optical element 14, and the printed wiring board 15 are each prepared.

The optical element 14 shown by imaginary lines in FIGS. 1 and 2 and shown by solid lines in FIG. 4 has a substantially plate shape having a size smaller than that of the opto-electrical hybrid board 1 in plan view. Specifically, the optical element 14 has a size to be placed in the inner region 13 within the PCB mounting bonding area 16. The optical element 14 includes an entrance/exit 21 and an electrode 22 on its lower surface.

The entrance/exit 21 is configured as a light exit for emitting light from the optical element 14 to the mirror 7, or is configured as a light entrance for receiving light from the mirror 7.

A plurality of electrodes 22 are provided corresponding to the second terminals 12.

Specifically, the optical element 14 includes a laser diode (LD) or a light emitting diode (LED) (including a VCSEL), which can receive electricity input from the second terminal 12 and emit light from the entrance/exit 21, for example. , a photodiode (PD) that receives light from the mirror 10 and outputs an electrical signal to the second terminal 12.

The printed wiring board 15 shown by the phantom lines in FIGS. 2 and 3 and the solid line in FIG. 4 extends in the longitudinal direction and has a substantially flat plate shape that is wider than the opto-electric hybrid board 1. When the printed wiring board 15 is mounted on the opto-electric hybrid board 1, the other end in the longitudinal direction corresponds to the above-described PCB mounting bonding area 16. Specifically, the other end of the printed wiring board 15 in the longitudinal direction has a shape in which the center in the width direction is cut out toward one side in the longitudinal direction into a substantially rectangular shape in plan view. Specifically, the other end of the printed wiring board 15 in the longitudinal direction has a substantially U-shape that opens toward the other side in the longitudinal direction when viewed from above.

The printed wiring board 15 includes a support plate 19 and a third terminal 20.

The support plate 19 has a plate shape extending in the longitudinal direction, and forms the outer shape of the printed wiring board 15. Examples of the material for the support plate 19 include hard materials such as glass fiber reinforced epoxy resin.

A plurality of third terminals 20 are provided corresponding to the plurality of first terminals 11. The plurality of third terminals 20 are arranged on the lower surface of the other end in the longitudinal direction of the support plate 19 in an array at intervals. Examples of the material for the third terminal 20 include conductive materials such as copper.

Next, in this method, the optical element 14 is first mounted on the opto-electrical hybrid board 1. Specifically, the electrode 22 and the second terminal 12 are connected by a known electrical connection method, and the entrance/exit 21 and the mirror 7 are optically connected.

Thereafter, in this method, a printed wiring board 15 is mounted on the opto-electrical hybrid board 1 on which the optical element 14 is mounted.

An example of a method for mounting the printed wiring board 15 is a method (1) in which the third terminal 20 and the first terminal 11 are electrically connected using ultrasonic waves.

In this method (1), first, the meltable member 25 is placed on the upper surface of the first terminal 11. Examples of the material of the meltable member include solder and gold.

Subsequently, the third terminal 20 is arranged so that the lower surface thereof contacts the upper end of the meltable member 25 .

Subsequently, ultrasonic vibration is applied to the first terminal 11 and/or the third terminal 20.

As a result, the meltable member 25 is melted (reflowed), and the first terminal 11 and the third terminal 20 are electrically connected.

Thereafter, if necessary, an adhesive (not shown) is poured into the PCB mounting bonding area 16 and then cured to bond the printed wiring board 15 and the opto-electrical hybrid board 1 together.

Further, as a method for mounting the printed wiring board 15, a method (2) using an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP) can be mentioned.

In method (2), an ACF or ACP (not shown) is interposed between the first terminal 11 and the third terminal 20, and then the opto-electric hybrid board 1, the printed wiring board 15, and the ACF or ACP are heat-pressed. do. The hot pressing conditions are appropriately set depending on the type of ACF or ACP used, and are selected so that the opto-electric hybrid board 1, the printed wiring board 15, and furthermore the optical element 14 are not damaged.

The above-described hot pressing causes the conductive particles to be oriented in the vertical direction in the ACF or ACP, thereby electrically connecting the first terminal 11 and the third terminal 20.

As a result, the optical element 14 and the printed wiring board 15 are mounted on the opto-electrical hybrid board 1.

In this opto-electrical hybrid board 1, the first terminal 11 is shifted from the optical waveguide 2 when projected in the vertical direction. That is, the first terminal 11 does not overlap the optical waveguide 2.

Therefore, in the method (1) of mounting the printed wiring board 15 on the opto-electrical hybrid board 1 using ultrasonic waves, while suppressing the ultrasonic waves from escaping to the optical waveguide 2, the first terminal 11 and The third terminal 20 of the printed wiring board 15 can be reliably connected. In addition, since the above-described effects can be achieved, it is possible to use ultrasonic waves of normal output, so damage to the opto-electrical hybrid board 1 can be suppressed, and specifically, the optical waveguide 2 can be prevented from peeling off from the electric circuit board 3. , it is possible to suppress an increase in transmission loss of the optical waveguide 2. Furthermore, damage to the optical element 14 mounted on the opto-electrical hybrid board 1 can be suppressed.

In addition, if method (2) is used in which the printed wiring board 15 is mounted on the opto-electrical hybrid board 1 by thermocompression bonding of ACF or ACP, the first terminal 11 and the third terminal 20 of the opto-electric hybrid board 1 can be reliably connected. In addition, since the above-described effect is achieved, the first terminal 11 can be thermocompression bonded at normal heating temperature and pressure, which prevents the optical waveguide 2 from peeling off from the electric circuit board 3 and increases the transmission loss of the optical waveguide 2. Furthermore, damage to the optical element 14 mounted on the opto-electrical hybrid board 1 can be suppressed.

Therefore, in this opto-electric hybrid board 1, damage to the opto-electric hybrid board 1 and the optical element 14 can be suppressed, and the first terminal 11 and the third terminal 20 of the printed wiring board 15 can be electrically connected with excellent connection reliability. can be connected.

In this opto-electrical hybrid board 1, the optical waveguide 2 is disposed on the inside in the width direction with respect to the electric circuit board 3 when viewed in cross section in the width direction, so that warpage can be reduced.

In this opto-electrical hybrid board 1, since the percentage of the area of the overlapping portion of the optical waveguide 2 and the electric circuit board 3 is 50% or less, warping of the opto-electric hybrid board 1 can be suppressed, and as a result, the electrical circuit Peeling of the optical waveguide 2 from the substrate 3 can also be suppressed. On the other hand, since the percentage of the area of the overlapping portion of the optical waveguide 2 and the electric circuit board 3 is 5% or more as described above, the degree of freedom in the arrangement of the optical waveguide 2 can be ensured, and the transmission of light on the opto-electrical hybrid board 1 can be ensured. characteristics can be secured.

In this opto-electrical hybrid board 1, since the percentage of the area of the overlapping portion of the metal support layer 8 and the base insulating layer 9 is 50% or less, warping due to the spring characteristics of the metal support layer 8 can be suppressed. Furthermore, peeling of the optical waveguide 2 from the electric circuit board 3 can also be suppressed. On the other hand, since the percentage of the area of the overlapping portion of the metal support layer 8 and the base insulating layer 9 is 5% or more, the degree of freedom in the arrangement of the metal support layer 8 can be ensured.

In this opto-electric hybrid board, since the plurality of first terminals 11 are arranged symmetrically with respect to the center line CL of the optical waveguide 3, warpage in the width direction of the opto-electric hybrid board 1 can be reduced.

<Modified example>
In each of the following modified examples, the same reference numerals are given to the same members and steps as in the above-described embodiment, and detailed explanation thereof will be omitted. In addition, each modification example can have the same effects as the one embodiment except as otherwise specified. Furthermore, one embodiment and its modified examples can be combined as appropriate.

In one embodiment, the upper limit of the percentage of the area of the overlapping portion of the optical waveguide 2 and the electric circuit board 3 is set to 50%, but is not limited to this, and is 100% or less, preferably 80% or less, More preferably, it may be 70% or less. Note that an aspect in which the percentage of the area of the overlapping portion of the optical waveguide 2 and the electric circuit board 3 is 70% is drawn by virtual lines in FIG.

In one embodiment, the upper limit of the percentage area of the overlapping portion of the metal support layer 8 and the base insulating layer 9 is set to 50%, but is not limited to this, and is 100% or less, preferably 80% or less. , more preferably 70% or less. Note that an aspect in which the area percentage of the overlapping portion of the metal support layer 8 and the base insulating layer 9 is 100% is drawn by a solid line in FIG.

As shown in the modified example of FIG. 5, the entire lower surface of the base insulating layer 9 is disposed on the upper surface of the metal support layer 8 in a cross-sectional view along the width direction.

In one embodiment, the optical waveguide 2 is arranged at the middle part in the width direction of the electric circuit board 3 in a cross-sectional view along the width direction, but for example, as shown in FIG. They may be placed at both ends.

In the modification shown in FIG. 6, the optical waveguide 2 includes a first optical waveguide 27 and a second optical waveguide 28, which are arranged separately at one end and the other end in the width direction of the opto-electric hybrid board 1, respectively. The first optical waveguide 27 and the second optical waveguide 28 are arranged at intervals from each other in the width direction. A plurality of first terminals 11 are arranged between the first optical waveguide 27 and the second optical waveguide 28 when projected in the vertical direction. The first optical waveguide 27 and the second optical waveguide 28 have the same layer structure, and specifically include an underclad layer 4, a core layer 5, and an overclad layer 6.

One end surface of the first optical waveguide 27 in the width direction is flush with one end surface of the electric circuit board 3 in the width direction. The other end surface of the second optical waveguide 28 in the width direction is flush with the other end surface of the electric circuit board 3 in the width direction.

On the other hand, the other end surface in the width direction of the first optical waveguide 27 and the one end surface in the width direction of the second optical waveguide 28 overlap (are included in) the electric circuit board 3 when projected in the vertical direction.

As shown in FIG. 7, one end of the first optical waveguide 27 in the width direction may protrude from the electric circuit board 3 to one side in the width direction. The other end of the second optical waveguide 28 in the width direction may protrude from the electric circuit board 3 to the other side in the width direction.

As shown in FIG. 8, an opening 29 can also be formed in a region of the optical waveguide 2 facing the first terminal 11. The opening 29 is a slit that vertically penetrates the undercladding layer 4 and overcladding layer 6 of the optical waveguide 2 and is parallel to the core portion 23 . One opening 29 includes a plurality of first terminals 11 (not shown in FIG. 8) when projected in the vertical direction. However, the outer shape of the optical waveguide 2 is the same as the outer shape of the electric circuit board 3.

As shown in FIG. 9, the plurality of first terminals 11 may be arranged asymmetrically with respect to the center line CL of the optical waveguide 2 in a cross-sectional view along the width direction. Specifically, the optical waveguide 2 is arranged on one side of the opto-electrical hybrid board 1 in the width direction. A plurality of first terminals 11 are arranged on the other side of the opto-electrical hybrid board 1 in the width direction.

Examples , Comparative Examples , and Reference Examples 2 to 4 are shown below to further specifically explain the present invention. Note that the present invention is not limited to Examples , Comparative Examples , and Reference Examples 2 to 4 in any way. In addition, the specific numerical values such as compounding ratios (ratios), physical property values, parameters, etc. used in the following descriptions are the corresponding compounding ratios (ratios) described in the above "Details of Carrying Out the Invention". ), physical property values, parameters, etc. can be replaced with the upper limit (a numerical value defined as "less than" or "less than") or the lower limit (a numerical value defined as "more than" or "exceeding").

Example 1 , Comparative Examples 1 and 2 , and Reference Examples 2 to 4
One hundred opto-electrical hybrid boards 1 corresponding to each of the figures listed in Table 1 were manufactured.

<Implementation evaluation>
First, each of the 100 optical elements 14 and each of the 100 printed wiring boards 15 were placed on each of the 100 opto-electrical hybrid boards 1 in each Example , each Comparative Example, and Reference Examples 2 to 4. , were implemented sequentially.

The printed wiring board 15 was bonded to the opto-electrical hybrid board 1 of Example 1 , Comparative Example 1 , and Reference Examples 2 to 4 using ultrasonic waves with a normal output of 1000 W.

On the other hand, a printed wiring board 15 was bonded to the opto-electrical hybrid board 1 of Comparative Example 2 using ultrasonic waves of 5000 W, which is a higher output than usual.

Thereafter, the following items were evaluated. The results are shown in Table 1.

(conductivity)
The conductivity between the opto-electric hybrid board 1 and the printed wiring board 15 of each Example , each Comparative Example , and Reference Examples 2 to 4 was determined.

(Amount of warpage)
The amount of warpage in the width direction of the opto-electric hybrid board 1 of each Example and Reference Examples 2 to 4 was determined using a laser microscope.

(Peeling rate of optical waveguide from electric circuit board)
The peeling rate of the optical waveguide 2 from the electric circuit board 3 in the opto-electrical hybrid board 1 of each Example , each Comparative Example, and Reference Examples 2 to 4 was determined using a laser microscope.

(Damage rate of optical element)
The damage rate of the optical element 14 mounted on the opto-electric hybrid board 1 of each Example , each Comparative Example , and Reference Examples 2 to 4 was determined using a laser microscope.

(Optical waveguide transmission loss)
The transmission loss of the optical waveguide 2 in the opto-electrical hybrid board 1 of each Example , each Comparative Example, and Reference Examples 2 to 4 was determined based on the output of the optical element 14 (VCSEL).

1 Optoelectric hybrid board 2 Optical waveguide 3 Electric circuit board 8 Metal support layer 9 Base insulating layer 11 First terminal 15 Printed wiring board CL Center line

Claims (4)

An optical waveguide and an electric circuit board are provided in order toward one side in the thickness direction,
The electric circuit board includes a terminal for electrically connecting to a printed wiring board,
The terminal is out of alignment with the optical waveguide when projected in the thickness direction,
The electric circuit board includes a metal support layer, a base insulating layer, and the terminal in order toward one side in the thickness direction,
In a cross-sectional view along the orthogonal direction perpendicular to the thickness direction, each of the two end portions of the base insulating layer in the orthogonal direction extends from each of the two end portions of the metal support layer in the orthogonal direction to each of the two outer sides in the orthogonal direction. protruding ,
An opto-electrical hybrid board, characterized in that a percentage of the area of the overlapping portion of the optical waveguide and the electrical circuit board with respect to the area of the electrical circuit board is 5% or more and 70% or less. 1 . The optical waveguide is disposed on the inner side of the electric circuit board in the orthogonal direction when viewed in cross section along an orthogonal direction that is orthogonal to the thickness direction and the light transmission direction. The opto-electrical hybrid board described in . The optoelectronic device according to claim 1 or 2, characterized in that the percentage of the area of the overlapping portion of the optical waveguide and the electrical circuit board with respect to the area of the electrical circuit board is 5% or more and 50% or less. Mixed board. A plurality of the terminals are arranged at intervals from each other in an orthogonal direction perpendicular to the thickness direction and the light transmission direction,
Any one of claims 1 to 3 , wherein the plurality of terminals are arranged symmetrically with respect to a center line passing through the orthogonal center portion of the optical waveguide along the transmission direction. The opto-electrical hybrid board according to item 1.