阅读说明：本技术 带光学元件的光电混载基板 (Opto-electric hybrid board with optical element ) 是由 古根川直人 铃木一聪 大田真也 于 2020-03-19 设计创作，主要内容包括：带光学元件的光电混载基板(1)具备：朝向厚度方向的一侧依次具备光波导(4)和电路基板(5)的光电混载基板(2)、在光电混载基板(2)的厚度方向的一侧安装于电路基板(5)的光学元件(3)、以将光学元件(3)与电路基板(5)接合的方式夹在它们之间的接合构件(20)。接合构件(20)的热膨胀系数为80ppm以下。(An optical-electrical hybrid substrate (1) with an optical element is provided with: an opto-electric hybrid board (2) provided with an optical waveguide (4) and a circuit board (5) in this order toward one side in the thickness direction, an optical element (3) mounted on the circuit board (5) on one side in the thickness direction of the opto-electric hybrid board (2), and a joining member (20) sandwiched between the optical element (3) and the circuit board (5) so as to join them. The thermal expansion coefficient of the joining member (20) is 80ppm or less.)

1. An opto-electric hybrid board with an optical element, comprising:

an opto-electric hybrid board including an optical waveguide and a circuit board in this order toward one side in the thickness direction,

An optical element mounted on the circuit board on one side in the thickness direction of the opto-electric hybrid board, and

a joining member sandwiched therebetween in such a manner as to join the optical element and the circuit substrate,

the joint member has a coefficient of thermal expansion of 80ppm or less.

2. The optical/electrical hybrid board with an optical element according to claim 1, wherein the bonding member has a thermal expansion coefficient of 10ppm or more.

3. The opto-electric hybrid board with an optical element according to claim 1, wherein a material of the bonding member has a 25 ℃ viscosity of 0.1Pa · s or more and 10Pa · s or less.

4. The optical-electrical hybrid board with an optical element according to claim 1, wherein the tensile modulus of the bonding member at 25 ℃ is 0.5GPa or more and 15GPa or less.

5. The opto-electric hybrid board with an optical element according to claim 12, wherein the glass transition temperature of the joining member is higher than 85 ℃.

6. The opto-electric hybrid board with an optical element according to claim 1, wherein the bonding member is a cured product obtained by heating a material thereof or a cured product obtained by heating a material thereof and irradiating an active energy ray.

Technical Field

The present invention relates to an opto-electric hybrid board with an optical element.

Background

An opto-electric hybrid board with an optical element is known, which includes: an opto-electric hybrid board, an optical element mounted thereon, and an underfill resin sandwiched therebetween (see, for example, patent document 1 below). The underfill resin of patent document 1 bonds the opto-electric hybrid board and the optical element.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2015-102648

Disclosure of Invention

Problems to be solved by the invention

However, in the optical-electrical hybrid board with an optical element described in patent document 1, the underfill resin and the vicinity thereof may be heated due to heat generation of the optical element. In this case, the mechanical strength of the underfill resin and its vicinity tends to be low, and the reliability of electrical connection between the optical element and the circuit board may be reduced due to this.

The invention provides an optical-electrical hybrid board with an optical element, which can inhibit the reduction of the mechanical strength of a bonding member with high temperature and the reduction of the electrical connection reliability of the optical element and a circuit board.

Means for solving the problems

The present invention (1) includes an opto-electric hybrid board with an optical element, including: an optical/electrical hybrid board comprising an optical waveguide and a circuit board in this order toward one side in a thickness direction, an optical element mounted on the circuit board on the one side in the thickness direction of the optical/electrical hybrid board, and a joining member interposed between the optical element and the circuit board so as to join the optical element and the circuit board, wherein the joining member has a coefficient of thermal expansion of 80ppm or less.

In the optical/electrical hybrid board with an optical element, since the coefficient of thermal expansion of the joining member is 80ppm or less, a decrease in the mechanical strength of the joining member that becomes high temperature due to heat generation of the optical element can be suppressed, and a decrease in the electrical connection reliability can be suppressed.

The invention (2) includes the optical/electrical hybrid board with an optical element according to (1), wherein the bonding member has a thermal expansion coefficient of 10ppm or more.

In the optical/electrical hybrid board with an optical element, the thermal expansion coefficient of the bonding member is 10ppm or more, and therefore stress applied to the bonding member can be reduced.

The invention (3) includes the opto-electric hybrid board with an optical element according to (1) or (2), wherein the material of the bonding member has a viscosity of 25 ℃ of 0.1Pa · s or more and 10Pa · s or less.

In addition, in the optical/electrical hybrid board with an optical element, since the material of the bonding member has a viscosity of 25 ℃ of 10Pa · s or less, the material can smoothly and reliably flow into between the optical element and the circuit board, and thus, a decrease in mechanical strength of the bonding member can be suppressed. Further, since the viscosity of the material at 25 ℃ is 0.1 pas or more, the material can be prevented from flowing out to the outside of the optical element and contaminating the surroundings.

The invention (4) includes the optical-element-equipped opto-electric hybrid board according to any one of (1) to (3), wherein the joining member has a tensile modulus of 0.5GPa or more and 15GPa or less at 25 ℃.

Further, in the optical/electrical hybrid board with an optical element, since the tensile modulus of the joining member at 25 ℃ is 0.5GPa or more, it is possible to suppress a decrease in the mechanical strength of the joining member and, in turn, a decrease in the electrical connection reliability between the optical element and the circuit board. On the other hand, the joint member has a tensile modulus at 25 ℃ of 15GPa or less, and therefore the joint member has excellent toughness.

The invention (5) comprises the opto-electric hybrid board with an optical element according to any one of (1) to (4), wherein the glass transition temperature of the joining member is higher than 85 ℃.

Further, since the glass transition temperature of the joining member exceeds 85 ℃ as described above, the joining member can suppress a decrease in the mechanical strength of the joining member which becomes a high temperature due to heat generation of the optical element.

The invention (6) includes the opto-electric hybrid board with an optical element according to any one of (1) to (5), wherein the bonding member is a cured product obtained by heating the material thereof or a cured product obtained by heating the material thereof and irradiating the material with an active energy ray.

In the optical/electrical hybrid board with an optical element, the joining member can be formed in a short time by heating the material or by heating and irradiation of active energy rays.

ADVANTAGEOUS EFFECTS OF INVENTION

In the optical/electrical hybrid board with an optical element according to the present invention, since the coefficient of thermal expansion of the joining member is 80ppm or less, a decrease in the mechanical strength of the joining member that becomes high in temperature due to heat generation of the optical element can be suppressed, and a decrease in the electrical connection reliability can be suppressed.

Drawings

Fig. 1 is a plan view showing one embodiment of an optical-electrical-hybrid-mounted substrate with an optical element according to the present invention.

Fig. 2 is a side cross-sectional view along the X-X line of the optical/electrical hybrid substrate with an optical element shown in fig. 1.

Detailed Description

< one embodiment >

An embodiment of an opto-electric hybrid board with an optical element according to the present invention will be described with reference to fig. 1 to 2.

As shown in fig. 1 to 2, the opto-electric hybrid board with optical element 1 includes an opto-electric hybrid board 2, an optical element 3, and a bonding member 20.

The opto-electric hybrid board 2 has a substantially rectangular sheet shape extending in the longitudinal direction. The opto-electric hybrid board 2 includes an optical waveguide 4 and a circuit board 5 in this order facing upward (one side in the thickness direction).

The optical waveguide 4 has the same planar shape as the opto-electric hybrid board 2. The optical waveguide 4 includes: a lower cladding 7; a core 8 disposed below the lower cladding 7; and an upper cladding 9 disposed below the lower cladding 7 so as to cover the core 8.

The core 8 extends along the length of the optical waveguide 4. The core 8 has, for example, a substantially rectangular shape in a front cross-sectional view. The core 8 has a surface at one end in the longitudinal direction flush with the surfaces of the lower cladding 7 and the upper cladding 9 at one end in the longitudinal direction. A mirror 10 is formed on the other end surface of the core 8 in the longitudinal direction. The mirror 10 is inclined so that an angle formed with the lower surface of the lower cladding 7 in a side cross-sectional view is 45 degrees.

Examples of the material of the optical waveguide 4 include transparent materials such as epoxy resin, acrylic resin, and silicone resin. From the viewpoint of heat resistance and optical signal transmission, an epoxy resin is preferably used.

The size of the optical waveguide 4 can be set as appropriate.

The thermal expansion coefficient of the optical waveguide 4 is, for example, more than 50ppm, preferably 60ppm or more, and, for example, 110ppm or less, preferably 90ppm or less. The method of measuring the thermal expansion coefficient of the optical waveguide 4 is the same as the method of measuring the thermal expansion coefficient of the joining member 20 described later.

The circuit board 5 is disposed on the upper surface of the optical waveguide 4. Specifically, the circuit board 5 is in contact with the entire upper surface of the optical waveguide 4. The circuit board 5 includes: a metal support layer 11, a base insulating layer 12, a conductor layer 13, and a cover insulating layer 14.

The metal supporting layer 11 is provided at least in a region corresponding to a 1 st terminal 15 (described later). In the vertical projection, the metal support layer 11 and the mirror 10 are offset from each other. Examples of the material of the metal supporting layer 11 include metal materials such as stainless steel.

The insulating base layer 12 is disposed on the upper surface of the metal supporting layer 11 and the upper surface of the under clad layer 7 on which the metal supporting layer 11 is not provided. Examples of the material of the insulating base layer 12 include insulating materials such as polyimide.

The conductor layer 13 includes a 1 st terminal 15, a 2 nd terminal 16, and a wiring 17.

The 1 st terminal 15 is disposed around the mirror 10 when projected in the vertical direction. The 1 st terminal 15 is arranged in a plurality of rows spaced apart from each other in the longitudinal direction and the width direction (the direction orthogonal to the longitudinal direction and the thickness direction). The shape of each of the 1 st terminals 15 in a plan view is not particularly limited.

The 2 nd terminals 16 are arranged in a row at the other end in the longitudinal direction of the insulating base layer 12 with a space therebetween in the width direction. The 2 nd terminal 16 is spaced apart from the 1 st terminal 15 on the other side in the longitudinal direction.

The wiring 17 connects the plurality of 1 st terminals 15 to the plurality of 2 nd terminals 16, respectively. A plurality of wirings 17 are arranged at intervals from one another.

Examples of the material of the conductor layer 13 include a conductor material such as copper.

The insulating cover layer 14 is disposed on the upper surface of the insulating base layer 12 so as to cover the wiring 16 (not shown in fig. 1 to 2). The material of the insulating cover layer 14 is the same as that of the insulating base layer 12.

A known circuit board can be used as the circuit board 5. The size of the circuit substrate 5 can be set as appropriate.

The thermal expansion coefficient of the circuit board 5 is, for example, 5ppm or more, preferably 10ppm or more, and is, for example, 50ppm or less, preferably 25ppm or less. The method of measuring the thermal expansion coefficient of the circuit board 5 is the same as the method of measuring the thermal expansion coefficient of the joining member 20 described later.

The thermal expansion coefficient of the circuit board 5 is lower than that of the optical waveguide 4, and specifically, the ratio of the thermal expansion coefficient of the circuit board 5 to that of the optical waveguide 4 (the thermal expansion coefficient of the circuit board 5/the thermal expansion coefficient of the optical waveguide 4) is, for example, 0.5 or less, further 0.4 or less, further 0.3 or less, and further, for example, 0.1 or more.

The thermal expansion coefficient of the circuit board 5 is obtained by actually measuring the circuit board 5 itself, or the thermal expansion coefficients of the metal supporting layer 11, the insulating base layer 12, the conductive layer 13, and the insulating cover layer 14 may be calculated by dividing the respective thermal expansion coefficients by the thickness ratios.

The optical element 3 is mounted on the opto-electric hybrid board 2. The optical element 3 is disposed above the circuit board 5 with a gap in the center of the other end portion in the longitudinal direction of the circuit board 5. The optical element 3 has a substantially box shape whose vertical length is shorter than the longitudinal length and the width length. The optical element 3 has a smaller plan view size than the opto-electric hybrid board 2. Specifically, the optical element 3 has a size including the plurality of 1 st terminals 15 when projected in the vertical direction. The lower surface of the optical element 3 is parallel to the upper surface of the opto-electric hybrid board 2. The optical element 3 has an inlet 21 and a 3 rd terminal 22 on its lower surface.

The entrance 21 is disposed opposite to the mirror 10. The inlet/outlet 21 is a light outlet capable of emitting light from the optical element 3 to the mirror 10 or a light inlet capable of receiving light from the mirror 10.

The 3 rd terminal 22 is disposed opposite to the 1 st terminal 15. The 3 rd terminals 22 are arranged in a plurality of rows on the lower surface of the optical element 3 at intervals in the longitudinal direction and the width direction. The plurality of 3 rd terminals 22 are provided corresponding to the plurality of 1 st terminals 15, respectively. The 3 rd terminal 22 is electrically connected to the 1 st terminal 15 via a conductive member 23 (described later). The conductive member 23 is, for example, a bump, and examples of the material thereof include metals such as gold and korean.

Specifically, examples of the optical element 3 include: a Laser Diode (LD) or a Light Emitting Diode (LED) that receives an electrical input from the 1 st terminal 15 and can emit light from the inlet 21, for example, a Photodiode (PD) that receives light from the mirror 10 and outputs an electrical signal to the 1 st terminal 15.

The bonding member 20 is interposed between the circuit board 5 and the optical element 3, and bonds the circuit board 5 and the optical element 3. The joint member 20 is referred to as an underfill member. Specifically, the bonding member 20 covers the entire lower surface of the optical element 3, and is disposed on the upper surface of the circuit board 5 in such a manner that: at least the 1 st terminal 15 is covered, and further, when the optical element 3 and the circuit board 5 are projected in a plan view, the region overlapping with the optical element 3 and the region in the vicinity of the outer side thereof are included. The joining member 20 covers the circumferential side surfaces of the plurality of conductive members 23.

Examples of the material of the joining member 20 include a liquid curable composition containing a curable resin (referred to as an underfill material).

Examples of the curable resin include: for example, a thermosetting resin curable by heating, for example, a thermo-photocurable resin curable by heating and irradiation of light (active energy ray), a photocurable resin curable by irradiation of light, for example, a moisture curable resin, and the like. These may be used alone or in combination of 2 or more. The types of the curable resins are not strictly distinguished.

Examples of the curable resin include epoxy resins, silicone resins, urethane resins, polyimide resins, urea resins, melamine resins, and unsaturated polyester resins. These may be used alone or in combination of 2 or more. When the curable resin contains an epoxy resin, the curable composition is regarded as an epoxy resin composition.

Examples of the epoxy resin include bifunctional epoxy resins and polyfunctional epoxy resins such as bisphenol a type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, brominated bisphenol a type epoxy resin, hydrogenated bisphenol a type epoxy resin, bisphenol AF type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, phenol novolac type epoxy resin, o-cresol novolac type epoxy resin, trishydroxyphenylmethane type epoxy resin, and tetraphenylolethane type epoxy resin. Examples of the epoxy resin include hydantoin type epoxy resins, triglycidyl isocyanurate type epoxy resins, and glycidyl amine type epoxy resins. These may be used alone or in combination of 2 or more.

Examples of the silicone resin include linear silicone resins such as methyl silicone resin, phenyl silicone resin, and methylphenyl silicone resin, and modified silicone resins such as alkyd-modified silicone resin, polyester-modified silicone resin, urethane-modified silicone resin, epoxy-modified silicone resin, and acrylic-modified silicone resin. These may be used alone or in combination of 2 or more.

When the curable composition is an epoxy resin composition, the curable composition may further contain a curing agent such as an imidazole compound or an amine compound. The curable composition may further contain a curing accelerator such as a urea compound, a tertiary amine compound, a phosphorus compound, a quaternary ammonium salt compound, or an organic metal salt compound.

When the curable resin is a thermo-photocurable resin or a photocurable resin, the curable composition may contain a photoinitiator, for example.

The curable composition may further contain a reactive monomer.

Further, the curable composition may contain a filler in addition to the above.

The filler is not particularly limited, and examples thereof include inorganic fillers such as aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, quartz glass, talc, silica, aluminum nitride, silicon nitride, and boron nitride, and organic fillers such as acrylic resin particles and silicone resin particles.

The curable composition may further contain additives such as a thermoplastic resin (acrylic resin and the like), a coupling agent, and a lubricant at an appropriate ratio.

The ratio of each component in the curable composition can be appropriately set according to the use and the purpose. The ratio of the curable resin in the curable composition is, for example, 50 mass% or more and 90 mass% or less. The ratio of the curing agent in the curable composition is, for example, 1 mass% or more, and, for example, 40 mass% or less. The ratio of the curing accelerator in the curable composition is, for example, 0.5% by mass or more, and for example, 10% by mass or less. The ratio of the reactive monomer in the curable composition is, for example, 1 mass% or more and 10 mass% or less. The ratio of the filler in the curable composition is, for example, 1 mass% or more and 40 mass% or less.

The viscosity at 25 ℃ of the material (curable composition) (a stage) is, for example, 0.1Pa · s or more, and is, for example, 25Pa · s or less, preferably 10Pa · s or less, and more preferably 5Pa · s or less.

When the viscosity at 25 ℃ of the material is not more than the upper limit, the material can smoothly and reliably flow into the space between the optical element 3 and the circuit board 5, and therefore, the reduction in the mechanical strength of the joining member 20 can be suppressed.

When the viscosity of the material at 25 ℃ is not lower than the lower limit, the material can be prevented from flowing out to the outside of the optical element 3 to contaminate the surroundings.

The viscosity of the material is determined, for example, by an EHD type viscometer.

As the material, commercially available products can be used, and specifically, Z-591-Y4 manufactured by Aica Kogyo Company, Limited, Z-591-Y6 manufactured by Aica Kogyo Company, Limited, 3553-HM manufactured by EMI Company, 8776-LS1 manufactured by Hitachi chemical industries, and the like can be used.

The joining member 20 is a cured product of the curable composition. Specifically, examples of the joining member 20 include: for example, a cured product obtained by heating a material, for example, a cured product obtained by heating a material and irradiating light, a cured product obtained by irradiating a material with light, for example, a cured product obtained by curing moisture in a material, and the like. A cured product obtained by heating the material, or a cured product obtained by heating the material and irradiating light can be preferably mentioned.

The thermal expansion coefficient of the joining member 20 is 80ppm or less, preferably 60ppm or less, more preferably 40ppm or less, and further preferably 30ppm or less. The thermal expansion coefficient of the joining member 20 is, for example, 1ppm or more, and further 10ppm or more.

When the coefficient of thermal expansion of the joining member 20 exceeds the upper limit, the mechanical strength of the joining member 20 which becomes high temperature due to heat generation of the optical element 3 is lowered, and further, the reliability of electrical connection between the optical element 3 and the circuit board 5 is lowered.

When the thermal expansion coefficient of the joining member 20 is equal to or higher than the lower limit, stress applied to the joining member 20 can be reduced.

On the other hand, the difference in thermal expansion coefficient between the joining member 20 and the optical waveguide 4 is, for example, 40ppm or less, preferably 30ppm or less, more preferably 20ppm or less, and 0ppm or more.

In the opto-electric hybrid board 2, the thermal expansion coefficient of the optical waveguide 4 is usually larger than the thermal expansion coefficient of the circuit board 5, but in the opto-electric hybrid board 1 with an optical element having a small difference, that is, in the opto-electric hybrid board 1 with an optical element having a bonding member 20 having a thermal expansion coefficient close to the thermal expansion coefficient of the optical waveguide 4, since the bonding member 20 having a small difference in thermal expansion coefficient and the optical waveguide 4 are disposed on both the upper and lower sides of the circuit board 5 having a small thermal expansion coefficient, it is possible to effectively suppress deformation of the region corresponding to the optical element 3 which becomes a high temperature due to heat generation of the optical element 3. Therefore, warpage of the opto-electric hybrid board 2 can be suppressed.

The coefficient of thermal expansion of the joining member 20 was measured by thermomechanical analysis (TMA).

The tensile modulus (young's modulus) of the joining member 20 at 25 ℃ is, for example, 0.01GPa or more, preferably 0.5GPa or more, preferably 2GPa or more, and is, for example, 20GPa or less, preferably 15GPa or less, more preferably 10GPa or less, and further preferably 5GPa or less.

When the tensile modulus of the joining member 20 is equal to or higher than the lower limit, it is possible to suppress a decrease in the mechanical strength of the joining member 20 and, in turn, a decrease in the electrical connection reliability between the optical element 3 and the circuit board 5.

When the tensile modulus of the joining member 20 is not more than the upper limit, the toughness of the joining member 20 is excellent.

The tensile modulus of the joining member 20 is measured in accordance with JIS K7127 (1999).

The glass transition temperature of the joining member 20 is, for example, 0 ℃ or higher, preferably 30 ℃ or higher, more preferably 75 ℃ or higher, and further preferably higher than 85 ℃, and is, for example, 150 ℃ or lower.

When the glass transition temperature of the joining member 20 is higher than the lower limit, it is possible to suppress a decrease in the mechanical strength of the joining member 20, which becomes high temperature due to heat generation of the optical element 3.

The glass transition temperature of the joining member 20 was calculated as a peak value of tan δ obtained from dynamic viscoelasticity measurement in a shear mode at a frequency of 1Hz and a temperature rise rate of 5 ℃/min.

Next, a method for manufacturing the opto-electric hybrid board 1 with an optical element will be described.

First, in this method, the opto-electric hybrid board 2 and the optical element 3 are prepared by a known method.

Next, in this method, the conductive member 23 is disposed on the upper surface of the 1 st terminal 15.

Next, the optical element 3 and the circuit board 5 are arranged to face each other so that the 3 rd terminal 22 contacts the upper end of the conductive member 23. In this case, the circuit board 5 is disposed on the opto-electric hybrid board 2 such that the distance between the lower surface of the optical element 3 and the upper surface of the circuit board 5 is, for example, 1 μm or more, further 5 μm or more, and, for example, 30 μm or less, preferably 10 μm or less.

Next, the material of the joining member 20 (specifically, a liquid curable composition) (a-stage curable composition) is poured between the circuit substrate 5 and the optical element 3.

The material is then, for example, cured.

Specific examples thereof include heating, irradiation with light, and standing in a moisture atmosphere. Heating alone may be preferable, and a combination of heating and light irradiation may be preferable.

Examples of the light include ultraviolet rays.

Thereby, the material is cured, and the bonding member 20 as a cured product thereof is formed. The optical element 3 is bonded (adhered) to the circuit board 5 by the bonding member 20.

At the same time as or before the material is cured, the conductive member 23 is reflowed to electrically connect the 1 st terminal 15 and the 3 rd terminal 22. The lead member 23 is reinforced by the joint member 20.

This yields an optical-device-mounted opto-electric hybrid board 1 including the opto-electric hybrid board 2, the optical device 3, and the bonding member 20 for bonding these components.

In the optical/electrical hybrid board 1 with an optical element, since the coefficient of thermal expansion of the joining member 20 is 80ppm or less, a decrease in the mechanical strength of the joining member 20 that becomes high temperature due to heat generation of the optical element 3 can be suppressed, and a decrease in the electrical connection reliability can be suppressed.

In addition, in the optical/electrical hybrid board 1 with an optical element, since the thermal expansion coefficient of the joining member 20 is 10ppm or more, the stress applied to the joining member 20 can be reduced.

In the optical/electrical hybrid board 1 with an optical element, if the material of the bonding member 20 has a viscosity of 25 ℃ of 10Pa · s or less, the material can smoothly and reliably flow into between the optical element 3 and the circuit board 5, and therefore, a decrease in the mechanical strength of the bonding member 20 can be suppressed. Further, if the viscosity of the material at 25 ℃ is 0.1Pa · s or more, when the material is caused to flow into between the optical element 3 and the circuit board 5, the material can be prevented from flowing out to the outside of the optical element 3 to contaminate the surroundings.

Further, in the optical/electrical hybrid board 1 with an optical element, if the tensile modulus of the joining member 20 at 25 ℃ is 0.5GPa or more, it is possible to suppress a decrease in the mechanical strength of the joining member 20 and, further, a decrease in the electrical connection reliability between the optical element 3 and the circuit board 5. On the other hand, if the tensile modulus of the joining member 20 at 25 ℃ is 15GPa or less, the toughness of the joining member 20 is excellent.

Further, if the glass transition temperature of the joining member 20 is higher than 85 ℃ as described above, even if the joining member 20 becomes high temperature due to heat generation of the optical element 3, a decrease in the mechanical strength of the joining member 20 can be suppressed.

In the optical/electrical hybrid substrate 1 with an optical element, if the material or the curable composition of the joining member 20 contains a thermosetting resin or a thermo-photocurable resin, the joining member 20 can be formed in a short time by heating the material or the curable composition, or by heating and irradiation with an active energy ray.

< modification example >

In the following modifications, the same members and steps as those of the above-described embodiment are given the same reference numerals, and detailed description thereof is omitted. Note that, if not specifically described, each modification can exhibit the same operational effects as those of the one embodiment. Further, one embodiment and its modifications can be combined as appropriate.

In one embodiment, the material of the joining member 20 is in a liquid state, but the material is not limited to this, and may be in a solid state or a semisolid state, for example.

Examples

The present invention will be further specifically described below by way of examples and comparative examples. The present invention is not limited to any examples and comparative examples. In addition, specific numerical values of the blending ratio (ratio), physical property value, parameter, and the like used in the following description may be substituted for the upper limit (numerical value defined as "lower" or "lower") or the lower limit (numerical value defined as "upper" or "higher") described in the above-described "embodiment" in correspondence with the blending ratio (ratio), physical property value, parameter, and the like described in the above-described "embodiment".

Examples 1 to 4 and comparative example 1

An opto-electric hybrid board 1 with an optical element was produced according to one embodiment.

The material of the joint member 20 is prepared by appropriately compounding an epoxy resin, an acrylic resin, and a filler. The bonding members 20 of examples 1 to 4 and comparative example 1 were each formed as a cured product obtained by heating the material at 100 ℃ for 3 hours.

< evaluation of physical Properties >

The following physical properties were evaluated. The results are set forth in Table 1.

[ thermal expansion coefficients of optical waveguide, circuit board, and bonding member ]

The thermal expansion coefficient of the joining member 20 was measured by TMA. Then, the thermal expansion coefficient of the optical waveguide 4 and the thermal expansion coefficient of the circuit board 5 were determined to be 75ppm and 18ppm, respectively.

[ viscosity of the Material of the joining Member ]

The viscosity of the material of the joining member 20 at 25 ℃ was measured by an EHD type viscometer.

[ tensile modulus of joining Member ]

The tensile modulus (Young's modulus) of the joining member 20 at 25 ℃ was determined in accordance with JIS K7127 (1999).

[ glass transition temperature of joining Member ]

The glass transition temperature of the joining member 20 was calculated as the peak value of tan δ obtained by dynamic viscoelasticity measurement in a shear mode at a frequency of 1Hz and a temperature rise rate of 5 ℃/min.

[ mechanical Strength of joining Member ]

The mechanical strength of the joining member 20 was determined as the peel strength when the optical element 3 was peeled from the opto-electric hybrid substrate 2. Specifically, the peel strength was measured by die shear test.

[ good product yield of opto-electric hybrid board with optical element ]

100 opto-electric hybrid boards 1 with optical elements were produced, and they were heated at 85 ℃ for 10 hours to carry out a heat resistance test. The optical element 3 and the circuit board 5 in the optical-electrical hybrid substrate 1 with optical elements after the test were subjected to conduction inspection, and the ratio of acceptable good products (good product rate) was determined.

[ Table 1]

The present invention is provided as an exemplary embodiment of the present invention, but this is merely an example and is not to be construed as a limitation. Variants of the invention that are obvious to a person skilled in the art are included in the scope of protection of the preceding claims.

Industrial applicability

The opto-electric hybrid board with an optical element can be used for communication and the like, for example.

Description of the reference numerals

1 opto-electric hybrid board with optical element

2 opto-electric hybrid board

3 optical element

4 optical waveguide

5 Circuit board

20 joining member