JP3185797B2 - Waveguide film with adhesive sheet and mounting method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide film with an adhesive sheet having highly stable optical characteristics and an adhesive sheet formed on one side or both sides of the waveguide film, and a mounting method thereof.

[0002]

2. Description of the Related Art In recent years, research on multi-channel parallel optical interconnection has been actively conducted for large-capacity information transmission, but key components for realizing this multi-channel parallel optical interconnection have been developed. As one, there is a waveguide film for connecting between a multi-core optical connector and a multi-channel optical element array.

As shown in FIG. 8, this waveguide film F
Is, for example, a polyimide film a of 16 mm × 13 mm
A high-refractive-index core layer c covered with a low-refractive-index cladding layer b is arranged in an array in a substantially rectangular shape at a desired interval (250 μm). An optical fiber array e is connected to one end face d, and an array g of light emitting diodes (or semiconductor lasers) or photodiodes is arranged on the other end face f. Also, this end face f
A 45 ° mirror i is formed on the side, and is configured to efficiently perform optical coupling with the light emitting diode or photodiode array g.

[0004] Such a waveguide film F is
It is obtained by a process as shown in FIG. That is, (a) a lower clad layer is formed on the surface of a plastic film, (b) a core layer is formed on the lower clad layer, and (c) a photoresist film is formed on the core layer. A photomask is placed on the photoresist film, and the photoresist film is exposed to UV light through the photomask. Next, (e) developing the photoresist film to form a photoresist pattern corresponding to the photomask, and (f) dry etching the core layer using the pattern. Then, (g)
The photoresist film is removed, (h) a substantially rectangular core layer pattern corresponding to the photoresist pattern is formed, and (i) an upper clad is formed so as to cover the core layer pattern. (J) 45 ° to waveguide end face
It is obtained by forming a mirror.

Further, such a waveguide film F is fixed and mounted on a substrate h by a mounting method as shown in FIG. That is, first, the fixing film j is provided on the substrate h, and the waveguide film F is fixed thereon, and then the optical fiber holder k and the buckling portion 1 are provided at the rear end of the waveguide film F. The optical fiber array e is attached by the BF connector interface m. In addition, this BF connector interface m
Is held by the connector holder n. Next, a VCSEL (surface emitting laser array) or a PD array (photodiode array) g is optically coupled to the front end side of the waveguide film F so as to be mounted on the substrate h.

[0006]

However, the conventional waveguide film F having such a configuration and the mounting method thereof have several problems as described below.

(1) First, since the waveguide film F changes its optical characteristics such as wavelength, loss, and polarization depending on the bending state and the stretching state, the waveguide film F maintains a certain bending or stretching state, ie, is uniform. It must be fixed in a state. However, the conventional waveguide film F does not employ such a firm fixing method, and its optical characteristics may change due to deformation with time.

(2) In addition, the thickness of the waveguide film is as follows:
Because it is a thin film in the range of 0 μm to several 100 μm,
There is a problem that the installation state is apt to change due to a change in wind pressure or humidity due to air conditioning in the room, and the optical characteristics also fluctuate accordingly.

(3) The conventional waveguide film F is an optical transmission line for optical wiring, and does not include a function of performing optical signal processing and electric signal processing.

(4) It is difficult to install and fix the waveguide film F at an arbitrary position with respect to the substrate, so that there is a drawback that mounting restrictions are large.

The present invention has been devised in order to effectively solve such a problem, and a main object of the present invention is to provide a novel waveguide film with an adhesive sheet having little change in optical characteristics and its mounting. It provides a method.

[0012]

According to a first aspect of the present invention, there is provided a high-refractive element having a substantially rectangular cross section in a low-refractive-index cladding layer on a plastic film. At least one core layer is embedded in the base material, and an ultraviolet curing type is provided on the back surface of the plastic or the upper surface or both surfaces of the clad layer .
It is a waveguide film with an adhesive sheet on which an adhesive sheet is formed.

According to a second aspect of the present invention, there is provided a waveguide film with an adhesive sheet, wherein the adhesive sheet is a thermosetting adhesive sheet .

According to a third aspect of the present invention, the adhesive sheet is a pressure-sensitive adhesive sheet.
This is a waveguide film with a groove .

According to a fourth aspect of the present invention, the refractive index of the adhesive sheet is larger than the refractive index of the core layer.
It is a waveguide film with an adhesive sheet having a higher thickness.

According to a fifth aspect of the present invention, as described in claim 5, between the plastic film and the adhesive sheet,
This is a waveguide film with an adhesive sheet on which at least one insulator layer and at least one copper foil layer are formed.

According to a sixth aspect of the present invention, there is provided a waveguide film with an adhesive sheet in which electronic circuits and electronic components are mounted on the insulator layer and the copper foil layer.

According to a seventh aspect of the present invention, there is provided a waveguide with an adhesive sheet, wherein the adhesive sheet surface side of the waveguide film with an adhesive sheet is attached to a substrate and mounted on the substrate. This is the implementation method.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a waveguide film 1 with an adhesive sheet according to the present invention.
(A) is a sectional view, and (b) is a plan view.

As shown, the waveguide film with an adhesive sheet (hereinafter, simply referred to as a waveguide film) 1 is
A plurality of core layers 4 each having a rectangular cross section are provided on one side of the cladding film (plastic film) 2 with a certain distance therebetween via a side cladding layer 3 (in the present embodiment, 6 layers).
And an upper clad layer 5 is formed on the upper surface thereof.

An adhesive sheet 6 having a refractive index higher than the refractive index of the core layer 4 is formed on the back side of the cladding film 2. It can be attached and fixed at the position.

Accordingly, the waveguide film 1 can be stuck on an arbitrary place or on various substrates by the adhesive sheet 6 so that the entire surface can be uniformly fixed. Of optical characteristics (wavelength characteristics, loss characteristics, polarization characteristics, etc.) can be extremely small.

In addition, since it can be fixed on the surface of the substrate having an arbitrary surface shape, the mountability is remarkably improved, and it is hardly affected by external influences such as changes in wind pressure and humidity. Properties can be obtained.

Further, since the light leaking and propagating to the side cladding layer 3 is absorbed and removed by the adhesive sheet 6, stable light propagation characteristics can be obtained.

Here, the material of the adhesive sheet 6 is not particularly limited, and may be polyolefin, urethane,
A thermosetting type such as acryl or silane, a pressure-sensitive type, an ultraviolet curable type, or the like can be used. Of these, in particular, if an ultraviolet (UV) curable adhesive sheet is used, it can be easily adhered to any place in a stress-relaxed state only by irradiating ultraviolet light, so that more stable optical characteristics can be maintained. It becomes possible.

The cladding film 2 is made of a material having a low refractive index, for example, an ultraviolet curable epoxy resin (refractive index 1.
471, a value at a wavelength of 0.83 μm), a fluorine-added polyimide film, or the like.

The core layer 4 is made of, for example, deuterated polymethyl methacrylate (refractive index: 1.489, wavelength: 0.83 μm). The side cladding layers 3 having a low refractive index on both sides of the core layer 4 are used. The upper clad layer 5 is made of, for example, a UV-curable epoxy resin.

In the present embodiment, the core layer 4
Is six, but this number is not limited to the present embodiment, and may be more, for example, 100 or more.

The waveguide film 1 can be applied to both single mode transmission and multimode transmission. That is, it can be configured for either single-mode transmission or multi-mode transmission simply by changing the size of the core layers 4, 4,... And the refractive index with the cladding layers 3, 5.

The thickness of the adhesive sheet 6 is 10 μm to 200 μm.
m, and the thickness of the cladding film 2 is also selected from the same range as the thickness of the adhesive sheet 6.

Next, another embodiment of the present invention will be described.

FIGS. 2 (1) to 2 (3) show second to second embodiments according to the present invention.
This shows a fourth embodiment. First, in the second embodiment, as shown in FIG. 2A, an adhesive sheet 6 is also provided on the upper clad 5 side. That is, by providing the adhesive sheets 6 and 6 on both sides as in the present embodiment, any one of the two sides can be arbitrarily bonded, so that the degree of freedom of selection increases. For example, an electronic component, an electronic circuit, an optical component, or the like may be bonded to one adhesive sheet 6 side and the other adhesive sheet 6 side may be bonded to a substrate and fixed, or the reverse method may be freely selected. It becomes possible. In addition, since the core layer 4 is sandwiched and fixed between the electronic component and the substrate from above and below, the fluctuation of the optical characteristics can be further suppressed. Further, unnecessary cladding modes propagating in the cladding layers 3 and 5 can be absorbed and removed by the adhesive sheets 6 and 6 on both sides.

On the other hand, in the third and fourth embodiments, FIG.
As shown in (2), a protective film 7 which can be peeled off is further provided on the surface of the adhesive sheet 6. Accordingly, it is possible to prevent dust and the like from being adhered to the adhesive sheet 6 after the manufacture of the waveguide film 1 and before mounting the same. Unnecessary adhesion can be prevented. When the adhesive sheets 6, 6 are formed on both sides as in the second embodiment, as shown in FIG. 2 (3), protective films 7, 7 are respectively applied to the adhesive sheets 6, 6 respectively. Needless to say, it is provided. The protective film 7 is made of cellophane or the like, and its thickness is selected from a range of several μm to 100 μm.

Next, FIGS. 3 to 5 show fifth to seventh embodiments according to the present invention, respectively. First,
In the fifth embodiment, as shown in FIG.
Is embedded in the cladding film 2, an insulating layer 8 made of a non-thermoplastic polyimide film and a copper foil layer 9 are formed below the cladding film 2, and an adhesive sheet 6 is formed below the copper foil layer 9. It was done. That is, with such a configuration, in addition to the above-described effects, the insulator layer 8 and the copper foil layer 9 can be used as a substrate material for an electronic circuit, and the layer above the cladding film 2 can be used for an optical circuit. Therefore, the film can be used also as a so-called optical / electric composite circuit configuration film.
Note that the thickness of the non-thermoplastic polyimide film to be the insulator layer 8 is preferably in the range of several μm to several tens of μm. Further, the thickness of the copper foil layer 9 is preferably in the range of 0.8 μm to several hundred μm, and various electric wiring patterns can be formed.

On the other hand, the sixth embodiment is the same as the first embodiment, except that an insulating layer 8 made of a non-thermoplastic polyimide film is further provided between the cladding film 2 and the adhesive sheet 6. The copper foil layer 9 is formed, while the seventh embodiment further comprises an adhesive sheet 6 on the cladding film 2 side in addition to the sixth embodiment. By doing so,
The film can also be used as a film for forming an electric composite circuit.

Next, FIG. 6 shows an embodiment of a mounting method of a combined optical / electrical mounting type device using the waveguide film 1 according to the first embodiment of the present invention. That is, a copper foil pattern 9 is formed on the waveguide film 1.
a, 9b, 9c are formed and an insulating layer 8 made of a non-thermoplastic polyimide film is formed thereon,
On the insulator layer 8, the upper conductor layers 10a, 10b, 10
c is provided. Then, this upper conductor layer 10a,
10b, 10c and lower copper foil patterns 9a, 9b, 9c
Are filled through holes 11a, 11b, 11c, respectively.
Are electrically connected. The upper conductor layer 10
a, 10b, and 10c and the non-thermoplastic polyimide film 8 are formed with resistors 12a, 12b, and 12c,
Further, the electronic component 1 is located between the upper conductor layers 10b and 10c.
3 are connected.

An optical signal is transmitted by such an optical / electric hybrid mounting type device, and the optical signal is processed and converted into an electric signal, and the signal can be processed by an electric circuit. A large-capacity information signal can be processed. In addition, since high-speed optical signals are transmitted in parallel in the respective core layers 4, 4... And converted into electric signals, high-speed electric signal processing can be performed with a very short wiring pattern, so that Gb / s to Tb
/ S and high-speed signal processing.

Next, FIG. 7 shows a state where the waveguide film 1 of the present invention is mounted on a substrate 15.

As shown in the figure, a pair of waveguide films 1a and 1b according to the present invention are bonded and fixed on the substrate 15 in such a manner that the tips thereof face each other. Optical fibers 16a and 16b are connected to the ends, respectively. An optical signal is transmitted into one optical fiber 16a as shown by an arrow, propagates through the core layer 4 of the waveguide film 1a, and is removed by the photodiode array 16. Light from the light emitting element array 17 propagates in the core layer 4 of the other waveguide film 1b, is coupled to the other optical fiber 16b, and propagates in the optical fiber 16b as shown by the arrow in the figure. In this configuration, an electric circuit for processing a signal converted into an electric signal by the photodiode array 16 and an electric driving circuit for driving the light emitting element array 17 are omitted, but actually on or in the substrate 15. Implemented in In addition, this waveguide film 1
a and 1b have at least two core layers arranged in an array.
And the same number as in the array. In addition, in FIG.
Is a core of the optical fiber, and 19 is a cladding of the optical fiber.

As described above, each waveguide film 1
When a and 1b are partially or wholly fixed on the surface of the substrate 15, an external force is applied by the flow of the air fan in the room where the substrate 15 is placed or the flow of air by the fan in the mounting housing. However, the waveguide film 1a,
Since the displacement and shape deformation of 1b do not occur, deterioration and fluctuation of optical characteristics do not occur. In addition, the photodiode array 16, the light emitting element array 17, and the waveguide films 1a, 1b
Since the displacement and fluctuation of the coupling position hardly occur, the optical characteristics are stabilized. In particular, if a UV-curable adhesive is used as the adhesive for the adhesive sheet 6, the adjustment of the optical coupling between the photodiode array 16 or the light emitting element array 17 and the waveguide films 1a and 1b becomes easy, and the adjustment and adhesion can be performed in a short time. Work can be completed.

Even when electronic components, optical components, electric circuits, optical circuits, and the like are mounted on the waveguide films 1a and 1b, the optical characteristics of the waveguide films 1a and 1b are hardly deteriorated. Therefore, a smaller optical / electric hybrid mounted device can be realized. If a thermosetting adhesive sheet is used, the adhesive sheet can be firmly adhered to a Si or ceramic substrate or a substrate, and can be heated and fixed together with other components (electronic components, optical components, etc.).

Further, it is possible to bond and fix the above-mentioned other parts either before or after heating and fixing.

In addition, when a pressure-sensitive adhesive sheet is used, it can be adhered to a flat planar substrate surface such as Si or glass only by pressing without applying unnecessary thermal stress. Since no thermal stress is applied, there is an advantage that the waveguide film 1 can be bonded and fixed without causing modulation.

Further, even when the surface has irregularities of several tens of μm, such as the surface of a ceramic substrate, it can be fixed by pressure bonding.

In the waveguide film 1 of the present invention, since the core layer, the clad layer, the adhesive sheet and the protective film are all made of a polymer material, their thermal expansion coefficients are close to each other, and the waveguide film 1 is resistant to temperature changes. Variations in optical characteristics are unlikely to occur. In addition, a circuit having small polarization dependence such as an optical multiplexing / demultiplexing circuit and an optical filter circuit can be realized.

The copper foil layer 9 shown in FIGS.
Is to dissipate heat in the copper foil 9 due to a change in optical characteristics due to a temperature change of an optical circuit such as an optical multiplexing / demultiplexing circuit, an optical filter, and an optical star coupler formed on the waveguide film 1 in addition to the function as an electric wiring pattern. With this, it also has a function of relaxing.

Further, in order to bend the waveguide film 1 with the adhesive sheet into a desired shape and maintain the shape, a copper foil 9 is used.
Works effectively.

In each of the above embodiments, the example of the waveguide film 1 in which the core layer 4 is formed in an array has been described, but other than that, an optical multiplexing / demultiplexing circuit, an optical filter circuit, an optical star coupler, etc. May be a waveguide film 1 with an adhesive sheet in which at least one is formed. Further, these may be configured in an array, or may be configured by combining these various optical circuits.

[0050]

In summary, according to the present invention, the following excellent effects can be exhibited.

(1) Since the waveguide film with an adhesive sheet of the present invention can be stuck to an arbitrary place or the surface of various substrates and fixed uniformly, it can be deformed over time, or subjected to shock or wind pressure during use. Less susceptible to external influences. As a result, fluctuations in the optical characteristics (wavelength characteristics, loss characteristics, polarization characteristics, etc.) of the optical signal propagating inside can be suppressed and the optical signals can be stabilized.

(2) The optical coupling characteristics between an optical component (photodiode, light emitting element, optical fiber, lens, etc.) optically coupled to one end or both ends of the waveguide film with an adhesive sheet of the present invention are stably maintained. can do.

(3) By fixing a substrate on the lower surface or the upper surface of the waveguide film with the adhesive sheet of the present invention, and further on both surfaces, electric parts, electronic circuits,
Even if optical components, optical circuits, etc. are mounted and arranged, the optical characteristics of the waveguide film with an adhesive sheet do not change,
High-density integrated mounting can be performed.

(4) The waveguide film with an adhesive sheet of the present invention has a structure in which electronic components and electronic circuits for processing not only optical signals but also electric signals can be integrated and mounted. A device capable of processing a large-capacity information signal can be realized.

(5) The waveguide film with an adhesive sheet according to the present invention may be an optical / electric combined mounting device having an electric signal processing circuit on the lower surface and an optical signal processing circuit on the upper surface. Alternatively, in contrast to the above, an optical signal processing circuit can be provided on the lower surface and an optical / electric hybrid mounting type device provided with an electric signal processing circuit on the upper surface, so that the light and the electricity are closely integrated. be able to.

(6) In the conventional waveguide film, the cladding mode, which leaks and propagates in the cladding layer, fluctuates due to bending or swinging of the waveguide film, which has an adverse effect on optical characteristics. In the waveguide film with an adhesive sheet according to the present invention, the above-mentioned cladding mode can be absorbed and removed by the adhesive sheet, so that optical characteristics can be stably maintained.

(7) By providing a copper foil layer, this copper foil layer can be used not only for forming an electric wiring pattern but also for dissipating heat, and as a function of holding a waveguide film in an arbitrary shape.

(8) Since the adhesive sheet is a material having a high light absorption rate, it works more effectively for removing the cladding mode.

(9) Since the core layer, the clad layer, the adhesive sheet, and the like, which constitute the waveguide film with the adhesive sheet of the present invention, are formed of materials having similar thermal expansion coefficients to each other, an optical circuit with little polarization dependence can be manufactured. It can be realized at a lower cost than a conventional structure in which a waveguide is formed on a Si or quartz glass substrate.

(10) In particular, UV hardening as an adhesive for an adhesive sheet
If the adhesive is used, the photodiode array 16 or
Light between the light emitting element array 17 and the waveguide films 1a and 1b
Easy adjustment of chemical bonding, and adjustment and bonding in a short time
Work can be completed.

(11) If a thermosetting adhesive sheet is used,
Can be firmly adhered to i or ceramic substrate, substrate
Heat and fix it together with other parts (electronic parts, optical parts, etc.)
It is also possible. In addition, heating and fixing of the other parts
Can be bonded and fixed before or after
It works.

(12) When a pressure-sensitive adhesive sheet is used
Is unnecessary on flat planar substrate surfaces such as Si and glass.
Adhesion can be performed only by crimping without applying thermal stress.
To avoid unnecessary thermal stress
Adhesive fixing to film 1 without modulation
There is a merit that can be done. Also, ceramic substrate
In the case where the surface has irregularities of several tens μm like the surface
Can also be fixed by crimping.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing one embodiment of a waveguide film with an adhesive sheet according to the present invention. (B) is a top view showing one embodiment of a waveguide film with an adhesive sheet concerning the present invention.

FIGS. 2A to 2C are cross-sectional views showing second to fourth embodiments of a waveguide film with an adhesive sheet according to the present invention.

FIG. 3 is a sectional view showing a fifth embodiment of the waveguide film with an adhesive sheet according to the present invention.

FIG. 4 is a sectional view showing a sixth embodiment of the waveguide film with an adhesive sheet according to the present invention.

FIG. 5 is a sectional view showing a seventh embodiment of the waveguide film with an adhesive sheet according to the present invention.

FIG. 6 is a cross-sectional view showing one embodiment of a combined optical / electrical device using a waveguide film with an adhesive sheet according to the present invention.

FIG. 7 is a cross-sectional view showing a state where the waveguide film with an adhesive sheet of the present invention is mounted on a substrate.

FIG. 8 is a perspective view showing an example of the configuration and structure of a conventional waveguide film.

FIG. 9 is a process chart showing an example of a conventional manufacturing process of a waveguide film.

FIG. 10 is a cross-sectional view showing a state where a conventional waveguide film is mounted on a substrate.

[Explanation of symbols]

 1 Waveguide film with adhesive sheet

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-222818 (JP, A) JP-A-4-152306 (JP, A) JP-A-6-281831 (JP, A) JP-A-10- 239542 (JP, A) JP-A-5-281428 (JP, A) JP-A-3-233410 (JP, A) JP-A-60-103319 (JP, A) IEICE Technical Report Vol. 99 No. 277 OPE99-45-53 (1999) p. 1-6 (Accepted by the Patent Office on September 16, 1999) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/12-6/14 G02B 6/42-6/43 H05K 1 / 00-1/02 JICST file (JOIS)

Claims (7)

(57) [Claims] At least one high-refractive-index core layer having a substantially rectangular cross section is embedded in a low-refractive-index cladding layer on a plastic film, and the back surface of the plastic film or the cladding layer has a high refractive index. A waveguide film with an adhesive sheet, wherein an ultraviolet-curable adhesive sheet is formed on the upper surface or on both surfaces thereof. 2. A low refractive index crystal on a plastic film.
There are few core layers of high refractive index with a substantially rectangular cross section in the lad layer.
At least one is embedded and the above plus
The back of the tic film or the top of the cladding layer
Has a thermosetting adhesive sheet on both sides
A waveguide film with an adhesive sheet, characterized in that: 3. A low refractive index crystal on a plastic film.
There are few core layers of high refractive index with a substantially rectangular cross section in the lad layer.
At least one is embedded and the above plus
The back of the tic film or the top of the cladding layer
Has a pressure-sensitive adhesive sheet on both sides.
And a waveguide film with an adhesive sheet. 4. The adhesive sheet according to claim 1, wherein said adhesive layer has a refractive index of said core layer.
The waveguide film with an adhesive sheet according to claim 1 , wherein the refractive index is higher than the refractive index of the adhesive sheet. 5. The waveguide with an adhesive sheet according to claim 1, wherein at least one insulator layer and at least one copper foil layer are formed between the plastic film and the adhesive sheet. the film. 6. The waveguide film with an adhesive sheet according to claim 5, wherein an electronic circuit and an electronic component are mounted on the insulator layer and the copper foil layer. 7. A waveguide film with an adhesive sheet, wherein the adhesive sheet surface side of the waveguide film with an adhesive sheet according to claim 1 is attached to a substrate and mounted on the substrate. How to implement.