CN103676039A - Optoelectronic circuit board for accurate alignment of light sources - Google Patents

Abstract

The invention relates to a photoelectric circuit board capable of accurately aligning a light source, which comprises a multilayer circuit board and more than two fixing pieces, wherein the multilayer circuit board is provided with one surface and more than one layer of optical waveguide which is not arranged on the surface, more than two aligning grooves are formed on the surface of the multilayer circuit board, the optical waveguide on the inner layer is exposed between the aligning grooves, the fixing pieces are provided with a top and a bottom, the fixing pieces are embedded into the aligning grooves in a shape matching manner, and the bottoms of the fixing pieces are provided with a photoelectric chip array and approach to the optical waveguide; the design can generate passive alignment effect by the fixing piece and the alignment groove on the multilayer circuit board, and shorten the distance between the photoelectric chip array arranged at the bottom of the fixing piece and the optical waveguide, so that the photoelectric chip array can accurately transmit the light source to the optical waveguide, and can effectively concentrate the light source, avoid the loss caused by light source scattering, and is beneficial to the lightening and thinning of elements.

Description

Optoelectronic circuit board for accurate alignment of light sources

technical field

The invention relates to a photoelectric circuit board, in particular to a photoelectric circuit board capable of accurately aligning light sources.

Background technique

Due to the comprehensive development of information technology, the bandwidth and capacity requirements of transmission media have increased sharply. However, in the traditional electrical field, the data transmission speed has encountered a bottleneck. Taking computer motherboards as an example, the central processing unit (CPU) The frequency has reached several GHz, but the transmission rate of the motherboard bus still stays at 10M to 100M, and the highest is no more than GHz. In order to break through the aforementioned bottleneck, the technology of replacing traditional lines with optical channels has come out.

A kind of known optoelectronic circuit board is as shown in Figure 6, mainly is to make a multilayer circuit board 70 contain an optical waveguide 71, and the surface of the multilayer circuit board 70 is formed with paired openings 701,702, the aforementioned optical waveguide 71 is exposed between the aforementioned openings 701,702, and two micromirrors 711,712 are formed at the exposed openings 701,702. When a light source is projected on the micromirrors 711,712, it will be reflected by the micromirrors 711,712 and transmitted through the optical waveguide 71.

In addition, the multi-layer circuit board 70 is provided with a transmitting element 72 and a receiving element 73 above the two openings 701, 702. The emitting element 72 and the receiving element 73 are respectively a ball grid array package (BGA) component and are installed in a reflow manner. On the multilayer circuit board 70 and electrically connected with other components on the multilayer circuit board 70; Wherein:

A surface-emitting laser chip array 721 and a driver IC 722 are respectively installed on the bottom surface of the emitting element 72, and each surface-emitting laser chip array 721 faces two micromirrors 711 respectively; and an optical sensor array 731 is provided on the bottom surface of the receiving element 73 And a receiving IC 732, each receiving chip 732 faces the micromirror 712, and is used for receiving the optical signal transmitted by the emitting element 72 through the optical waveguide 71.

Since the aforementioned multi-layer circuit board 70 uses the transmitting element 72, the receiving element 73 and the optical waveguide 71 to replace the traditional circuit, although the data transmission rate can be greatly improved, it is still difficult to call the distribution in terms of hardware design, which will affect the quality of data transmission. The problem:

1. It is difficult to align the light source, so the possibility of loss is high: as mentioned above, the emitting element 72 and the receiving element 73 are both BGA elements. Thus, the distance between the surface-emitting laser chip array 721 and the micromirror 711 is enlarged, and the possibility of alignment deviation of the surface-emitting laser chip array 721 is also increased, as shown in FIG. 7 , which reveals that the surface-emitting laser chip array 721 The array 721 projects the light source on the micromirror 711, transmits it through the optical waveguide 71 and receives it by the receiving chip 732. As shown in FIG. 8, it is the relationship between the different offset degrees of the surface-emitting laser chip array 721 and the loss of the light source. , which shows that the larger the alignment deviation of the surface-emitting laser chip array 721 is, the larger the loss is. Therefore, the alignment of the light source is very important, but the surface-emitting laser chip array 721 is limited by the installation method of BGA components, so it is relatively difficult to align accurately.

2. The installation of the ball grid array element is relatively complicated. As mentioned above, the transmitting element 72 and the receiving element 73 composed of BGA elements must be installed in a reflow mode, which is relatively complicated in terms of installation technology, and also improves the surface-emitting laser. Chip array 721 has the possibility of misalignment.

As can be seen from the above, the existing multilayer circuit board uses the optical waveguide 71 to transmit signals by the receiving element 73 and the emitting element 72, which can greatly increase the signal transmission rate. However, since the surface-emitting laser chip array 721 is installed at most On the multilayer circuit board 71, not only the work is complicated, but also affects the accuracy of the alignment of the surface-emitting laser chip array 721, and further leads to the problem of loss. Therefore, further research and improvement are required, and it is necessary to seek a feasible solution.

Contents of the invention

Therefore, the main purpose of the present invention is to provide a photoelectric circuit board that can accurately align the light source. It adopts a special buried alignment fixing structure, and the photoelectric chip array is installed on the multi-layer circuit board, which is completed at the same time as the installation. Alignment, and can shorten the distance between the photoelectric chip array and the optical waveguide, so as to effectively reduce loss and improve transmission efficiency.

The main technical means taken for reaching the aforementioned purpose is to make the aforementioned optoelectronic circuit board include:

A multi-layer circuit board has one surface and more than one layer of optical waveguide not on the surface, and more than two alignment grooves are formed on the surface, and the optical waveguide of the inner layer is exposed between the alignment grooves. A reflective mirror surface is formed at the alignment groove;

More than two fixing pieces are embedded in the alignment grooves in a matching shape, and each fixing piece has a top and a bottom respectively, and the bottom part is provided with a photoelectric chip array and is opposite to the reflective mirror surface of the optical waveguide;

Preferably, the multilayer circuit board includes first to third substrates, the first substrate is provided with a transmitting circuit and a receiving circuit, and the alignment grooves are respectively formed adjacent to the transmitting circuit and the receiving circuit;

The optical waveguide is located on the second substrate. An oblique cut is formed on the surface of the second substrate where the alignment groove is exposed, so that the optical waveguide is exposed below the alignment groove. The oblique cut has an oblique wall on which a reflection is formed. Mirror, the reflective mirror is relative to the optical waveguide.

Preferably, the photoelectric chip array and the photosensor array are mounted to the bottom of the fixture by wire bonding;

There is an interlayer conduction structure between the bottom and the top of the fixture, and solder pads corresponding to the photoelectric chip array or photosensor array are provided on the top of each fixture;

More than one driver IC is provided on the surface of the first substrate, and is electrically connected to the welding pad on the fixing member.

Preferably, a low-fluidity adhesive layer is respectively provided between the first substrate and the second substrate, and between the second substrate and the third substrate.

Preferably, the top of the fixing member is lower than the surface of the first substrate.

Preferably, the photoelectric chip array is a surface-emitting photoelectric chip array, and the photosensor array is a photodiode array.

Preferably, the alignment groove on the first substrate and the longitudinal section of the fixing member are stepped.

Preferably, the first substrate and the third substrate respectively have multiple copper circuit layers.

Preferably, the second substrate further includes a flexible insulating material and more than one layer of copper foil to make the second substrate flexible.

Preferably, more than one opening is respectively formed on the first and third substrates.

According to the photoelectric circuit board designed above, the photoelectric chip array is installed on the bottom of the fixing part, and then the fixing part is embedded in the alignment groove of the multilayer circuit board in a shape-matching manner. Since the alignment groove and the reflective mirror of the optical waveguide can be accurately aligned Alignment, the photoelectric chip array can also be accurately installed on the designated position at the bottom of the fixing piece, and then the shape of the fixing piece matches the alignment groove, so when the fixing piece is embedded in the alignment groove, the photoelectric chip array on the fixing piece can be simultaneously aligned. The alignment between the chip array and the reflective mirror on the optical waveguide can be effectively avoided, thus effectively avoiding alignment deviation and the resulting loss.

Furthermore, the above-mentioned fixing parts are embedded in the alignment groove of the multi-layer circuit board in a buried manner, which can not only meet the requirements of lightness and thinning, but also shorten the distance between the photoelectric chip array and the reflective mirror on the optical waveguide, and further avoid alignment problems. The generation of deviation and loss.

Description of drawings

Fig. 1 is a sectional view of the first embodiment of the present invention.

Fig. 2 is a schematic diagram of the multi-layer structure of the first embodiment of the present invention.

Fig. 3 is another cross-sectional view of the first embodiment of the present invention (before installing the fixing member).

Fig. 4 is a sectional view of the second preferred embodiment of the present invention.

Fig. 5 is a cross-sectional view of a third preferred embodiment of the present invention.

Fig. 6 is a schematic cross-sectional view of a known photoelectric circuit board.

FIG. 7 is a schematic diagram of a conventional optoelectronic circuit board transmitting and receiving signals through an optical waveguide.

Fig. 8 is a characteristic curve diagram of the relationship between alignment deviation and loss of the laser light source of the known photoelectric circuit board.

Explanation of main component symbols

10 multi-layer circuit board 11 first substrate

110,130 openings 111 copper wiring layer

12,12' second substrate 120 optical waveguide

121 Mirror surface 122 Flexible insulating material

123 copper foil layer 13 third substrate

131,132,135 copper wiring layer 133,136 epoxy resin layer

134 solder mask 14 low fluidity adhesive layer

15,16 alignment slot 150,160 oblique cut

20 Fixing parts 21 Welding pads

30 photoelectric chip array 40 light sensor array

50 driver ICs 70 multilayer circuit boards

701,702 opening 71 optical waveguide

711,712 micromirrors 72 emitting elements

721 surface-emitting laser chip array 722 driver IC

73 receiving elements 731 light sensor array

732 Receive IC.

Detailed ways

Regarding the first preferred embodiment of the present invention, as shown in Figure 1, it includes a multilayer circuit board 10 and more than two fixing parts 20; wherein:

In this embodiment, the multilayer circuit board 10 is composed of first to third substrates 11, 12, 13. As shown in FIG. 2, between the first substrate 11 and the second substrate 12, the second A low-fluidity adhesive layer 14 is provided between the substrate 12 and the third substrate 13 by coating or pressing, so as to adhere to each other.

As shown in FIG. 3, the first to third substrates 11, 12, and 13 are respectively a multi-layer structure composed of multi-layer substrates; wherein:

The first substrate 11 contains a multi-layer copper circuit layer 111, the inner layer of the second substrate 12 contains an optical waveguide 120, and the third substrate 13 is provided with an epoxy resin layer (FR-4) 133 between the two copper circuit layers 131,132 A solder resist layer 134 is disposed on the outer surface of the copper circuit layer 132 located on the opposite outer side.

As mentioned above, the first substrate 11 has a copper circuit layer 111, so the transmitting circuit (TX) and the receiving circuit (RX) can be fabricated, and the present invention forms a pair of circuits adjacent to the transmitting circuit and the receiving circuit respectively on the first substrate 11. The alignment grooves 15, 16, the alignment grooves 15, 16 are as deep as the surface of the second substrate 12, in this embodiment, the longitudinal sections of the two alignment grooves 15, 16 are in a stepped shape, that is, the alignment grooves 15, 16 The walls of the tank are stratified. And the surface of the second substrate 12 forms an oblique cut 150,160 at the position where the alignment grooves 15,16 are exposed, and the oblique cut 150,160 is deep below the optical waveguide 120, so that the optical waveguide 120 is exposed below the alignment groove 15,16, and the oblique incision 150 and 160 have a 45-degree inclined wall on which a reflective mirror surface 121 is formed, and the reflective mirror surface 121 is opposite to the optical waveguide 120 in the horizontal direction.

As shown in FIG. 1 , each fixing piece 20 is embedded in the alignment grooves 15 and 16 of the first substrate 11 in a form-matching manner in an embedded manner. In this embodiment, the longitudinal section of the fixing piece 20 is stepped, suitable for It can be correspondingly embedded in the alignment grooves 15, 16. The fixing member 20 has a top and a bottom, and a photoelectric chip array is respectively provided on the bottom. In this embodiment, each fixing member 20 is respectively equipped with a photoelectric chip An array 30 and a photosensor array 40, wherein the optoelectronic chip array 30 can be a surface-emitting laser (VCSEL) chip array, and the photosensor array 40 can be a photodiode (PD) array.

In this embodiment, the photoelectric chip array 30 and the photosensor array 40 are respectively mounted to the bottom of the fixture 20 by wire bonding. There is an interlayer conductive structure between the bottom and the top of the fixture 20. Make the top of the fixture 20 respectively have welding pads 21 corresponding to the photoelectric chip array 30 or the photosensor array 40, and then use the wire bonding method to make the welding pads 21 and the copper pads provided on the surface of the first substrate 11 pass through the first substrate 11 The circuit on the top is electrically connected with the driving IC 50 or other components.

Since the photoelectric chip array will generate high heat when it is in operation, the fixing member 20 can be made of high thermal conductivity material so as to transfer the heat energy generated at the bottom due to the operation of the photoelectric chip array to the surface of the fixing member 20 for dissipation.

As mentioned above, each fixing piece 20 is embedded in the alignment grooves 15, 16 of the multilayer circuit board 10, and the bottom of the fixing piece 20 will be closer to the optical waveguide 120 of the second substrate 12, which means This also reduces the distance (within about 180um) between the photoelectric chip array disposed on the bottom of the fixing member 20 and the reflective mirror surface 121 on the optical waveguide 120 . In this embodiment, the top of the fixing member 20 is lower than the surface of the multilayer circuit board 10 (first substrate 11), but those skilled in the art can understand that: whether the fixing member 20 is completely or not completely located on the first In the alignment grooves 15 and 16 of the substrate 11, as long as the volume of the fixing member 20 embedded in the alignment grooves 15 and 16 is greater than the volume exposed on the surface of the first substrate 11, it is covered by the so-called buried method, that is, the fixing member 20 The top may be lower, equal or higher than the surface of the first substrate 11 .

In the foregoing embodiments, the photoelectric chip array is mounted on the bottom of the fixture 20 with a specific shape meaning, and cooperates with the alignment grooves 15, 16 on the multilayer circuit board 10 and the fixture 20 that have a corresponding relationship in position and shape. , when the photoelectric chip array is installed on the multilayer circuit board 10 through the fixing member 20, the alignment is completed with the reflective mirror surface 121 on the optical waveguide 120, which not only simplifies the installation of the photoelectric chip array, because the photoelectric chip array is in advance Installed on the bottom of the fixing part 20, when the fixing part 20 must be aligned when embedded in the alignment grooves 15 and 16, it can avoid damage to the photoelectric chip array and the surface of the multilayer circuit board 10 due to collision.

Furthermore, since the fixing member 20 is embedded in the alignment grooves 15, 16, the photoelectric chip array at the bottom of the fixing member 20 can be closer to the reflective mirror surface 121 of the optical waveguide 120, and the distance is shortened. Paralocation shift and its resulting energy loss can be further avoided.

Regarding the second preferred embodiment of the present invention, as shown in FIG. 4, its structure is substantially the same as that of the previous embodiment, except that the second substrate 12' of the multilayer circuit board 10 further includes a flexible insulating material 122 and more than one layer of copper foil layer 123, so as to make the second substrate 12' flexible. In order to make the multilayer circuit board 10 easy to bend, a The above openings 110, 130 are used to provide an elastic space for expansion and contraction of the multilayer circuit board 10 when it is flexed.

As shown in Figure 5, the structure of the third embodiment of the present invention is substantially the same as that of the second preferred embodiment, except that the multilayer circuit board 10 has a plurality of copper wiring layers 131, 132, 135, and each copper wiring layer 131, 132, 134 Between them are epoxy resin layers 133, 136, respectively.

Although the present invention has been disclosed above with preferred embodiments, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention should be based on the scope defined in the claims.

Claims (10)

1. can make an optronic circuit board for light source accurate contraposition, it is characterized in that, include:

A multilayer circuit board, has a surface and one deck above not in surperficial optical waveguide, and its surface is formed with plural alignment grooves, and the optical waveguide of internal layer is exposed between alignment grooves, and this optical waveguide forms respectively a mirror surface in exposing alignment grooves place;

Plural fixture, form fit ground embeds in alignment grooves, and each fixture has respectively a top and a bottom, and its bottom is arranged with a photoelectric chip array and sensor array and respectively with respect to the mirror surface of optical waveguide.

2. can make according to claim 1 the optronic circuit board of light source accurate contraposition, it is characterized in that, this multilayer circuit board comprises the first to the 3rd substrate, and first substrate is provided with a radiating circuit and a receiving circuit, and forms respectively this alignment grooves at contiguous radiating circuit, receiving circuit place;

This optical waveguide is positioned on second substrate, and this second substrate surface, exposing an angular cut of alignment grooves place formation, makes optical waveguide be exposed to the below of alignment grooves, and this angular cut has a skew wall, forms a mirror surface on skew wall, and mirror surface is with respect to optical waveguide.

3. can make according to claim 2 the optronic circuit board of light source accurate contraposition, it is characterized in that, this photoelectric chip array, photosensor array are mounted to respectively the bottom of fixture in routing mode;

Between the bottom of this fixture and top, there is interlayer conduction structure, and at the top of each fixture, be respectively equipped with the weld pad corresponding to photoelectric chip array or photosensor array;

This first substrate surface is provided with more than one drive IC, and is electrically connected to the weld pad on fixture.

4. can make according to claim 3 the optronic circuit board of light source accurate contraposition, it is characterized in that, between this first substrate and second substrate, be respectively equipped with lazy flow glue-line between second substrate and the 3rd substrate.

5. can make according to claim 4 the optronic circuit board of light source accurate contraposition, it is characterized in that, the top of this fixture is lower than first substrate surface.

6. can make according to claim 5 the optronic circuit board of light source accurate contraposition, it is characterized in that, this photoelectric chip array is wall emission photoelectric chip array, and this photosensor array is photodiode array.

7. according to making the optronic circuit board of light source accurate contraposition described in any one in claim 2 to 6, it is characterized in that, the alignment grooves on this first substrate and the longitudinal cross-section of fixture are notch cuttype.

8. can make according to claim 7 the optronic circuit board of light source accurate contraposition, it is characterized in that, this first substrate, the 3rd substrate have respectively multilevel copper wiring layers.

9. can make according to claim 8 the optronic circuit board of light source accurate contraposition, it is characterized in that, this second substrate further comprises deflection insulation material and a copper foil layer more than one deck, second substrate is had flexible.

10. can make according to claim 9 the optronic circuit board of light source accurate contraposition, it is characterized in that, on this first, the 3rd substrate, form respectively more than one opening.

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