KR100872748B1 - Photoelectric conversion module and fabricating method thereof - Google Patents

Abstract

The photoelectric conversion module and the manufacturing method thereof are provided to improve the light coupling efficiency by connecting directly the optical guide to the optical device array and printed circuit board. The photoelectric conversion module for improving the light coupling efficiency comprises the printed circuit board(100) having the groove, the ductility integrated circuit board(110) in which one end is bent to the groove, the optical device array(120) formed on the ductility IC of the substrate, the optical guide whose one end is photo-connected to the optical device array(130), the epoxy(150) which surrounds the ductility integrated circuit board and optical device array, and the semiconductor chip(140) having the driver circuit.

Description

Photoelectric conversion module and fabrication method

1 is a cross-sectional view showing a conventional photoelectric conversion module.

2 is a cross-sectional view showing a first embodiment of a photoelectric conversion module of the present invention.

3 is a cross-sectional view showing a second embodiment of a photoelectric conversion module of the present invention.

Figure 4 is a flow chart showing a manufacturing method of a photoelectric conversion module of the present invention.

5 is a cross-sectional view showing a third embodiment of a photoelectric conversion module of the present invention.

Explanation of symbols on the main parts of the drawings

100: printed circuit board 105: groove

110: flexible IC substrate 120: optical element array

130: optical waveguide array 140: semiconductor chip

150: epoxy

The present invention relates to a photoelectric conversion module and a method of manufacturing the same.

In recent years, information and communication technology has tended to increase the speed and capacity of data to be transmitted, and the development of optical communication technology for realizing a high-speed communication environment has been in progress.

In general, optical communication converts an electrical signal into an optical signal in a photoelectric conversion element on a transmitting side, transmits the converted optical signal to a receiving side using an optical fiber or an optical waveguide, and receives the optical signal received in the photoelectric conversion element on the receiving side. Converts to an electrical signal.

In order for such a photoelectric conversion element to be applied and commercialized in a system, an electrical connection and an optical connection must be efficiently configured.

1 is a cross-sectional view showing a conventional photoelectric conversion module.

As shown in the drawing, a ball grid array (BGA) package 20 in which an optical element 30 is mounted on a printed circuit board (PCB) 10 is a solder ball. It is joined by (23).

The printed circuit board 10 and the ball grid array package 20 are aligned and bonded to each other by alignment balls 12 formed in the V-groove 11 of the printed circuit board. Through the same alignment, the light generated from the optical device 30 of the ball grid array package is incident on the optical waveguide 15 of the printed circuit board 10.

The ball grid array package 20 is fused to a semiconductor chip 21 in which electronic circuits are integrated, a circuit board 22 for mounting the semiconductor chip 21, and a lower surface of the circuit board 22. And a solder ball 23 for bonding the printed circuit board 10 and the ball grid array package 20 to the upper surface of the circuit board 22 to protect the semiconductor chip 21 from an external environment. It is made of a protective resin 24 formed surrounding.

An optical element 30 driven in accordance with a signal transmitted from the semiconductor chip 21 is bonded to the lower portion of the semiconductor chip 21 of the ball grid array package 20 by solder bumps 35. have.

The semiconductor chip 21 and the optical device 30 are electrically connected by the solder bumps 35, and the optical device 30 bonded to the lower portion of the semiconductor chip 21 corresponds to the optical waveguide 15. It is fixed at the position.

The optical device 30 may be a light emitting device or a light receiving device, and in the case of a light emitting device, a vertical cavity surface emitting laser (VCSEL) or a light emitting diode (LED) may be used. In the case of a light receiving device, a photo diode (PD) may be used. Used.

In the conventional photoelectric conversion module configured as described above, the optical device 30 is driven in accordance with a control signal generated from the semiconductor chip 21, and the optical device 30 converts an electrical signal into an optical signal and outputs the optical signal. .

The optical signal output from the optical device 30 is reflected through a 45 degree mirror 16 formed at one end surface of the optical waveguide 15 of the printed circuit board 10 to travel inside the optical waveguide 15.

The conventional photoelectric conversion module having such a configuration has no problem in the electrical connection between the ball grid array package 20 in which the optical element 30 is mounted and the printed circuit board 10, but the optical of the optical element 30 and the printed circuit board Optical interconnections between the waveguides 15 include many problems.

That is, the conventional photoelectric conversion module has a disadvantage in that the optical connection efficiency is very low due to the mutually spaced distance between the optical element 30 and the optical waveguide 15.

For example, when the VCSEL is used as the optical device 30, the VCSEL has a diverging angle of about 25 degrees to about 30 degrees when emitting light in the air, so that the distance from the optical waveguide 15 becomes long. As the optical coupling efficiency decreases significantly.

In order to solve this problem, a method of improving optical coupling efficiency by providing a lens between the optical element 30 and the optical waveguide 15 has been proposed. There is a need for an additional process to install between the), which is an obstacle to mass production.

Meanwhile, the conventional photoelectric conversion module forms a 45 degree mirror 16 on one end surface of the optical waveguide 15 of the printed circuit board 10 and reflects the light emitted from the optical element 30 so as to reflect the optical waveguide 15. In the process of manufacturing the photoelectric conversion module, the 45-degree mirror 16 needs many steps, and in the process, the reliability of the photoelectric conversion module is greatly reduced.

Accordingly, an object of the present invention is to form a groove in a printed circuit board, and to make one end of the flexible IC substrate having the optical element array bent in the groove of the printed circuit board, and then an optical waveguide embedded in the optical element array and the printed circuit board. By directly connecting the array, to provide a photoelectric conversion module and a method of manufacturing the improved optical coupling efficiency.

A preferred embodiment of the photoelectric conversion module of the present invention is a printed circuit board having a groove, a flexible IC substrate formed at an upper portion of the printed circuit board and curved at one end thereof, and a flexible IC substrate having a curved portion thereof. An optical element array formed in the substrate, an optical waveguide array embedded in the printed circuit board, one end of which is optically connected to the optical element array in the groove, and enclosing the flexible IC substrate and the optical element array in the groove of the printed circuit board. And a semiconductor chip having a filled epoxy and a driving circuit formed on the flexible IC substrate and driving the optical element array.

A preferred embodiment of the method of manufacturing a photoelectric conversion module of the present invention comprises the steps of: forming a semiconductor chip on the flexible IC substrate, and forming an optical element array driven by the semiconductor chip on one end of the flexible IC substrate; Forming a groove in which one end of the flexible IC substrate having the optical element array formed on the printed circuit board is bent, and bonding the flexible IC substrate to the printed circuit board, and the optical element array of the flexible IC substrate Bonding the optical element array and the optical waveguide array embedded in the printed circuit board to optically connect the formed part to be bent into the groove of the printed circuit board, and connecting the flexible IC to the groove of the printed circuit board. Wrapping the substrate and the array of optical devices, characterized in that it comprises a step of filling the epoxy.

Hereinafter, the photoelectric conversion module of the present invention and a manufacturing method thereof will be described in detail with reference to FIGS. 2 to 5. In describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or an operator. Therefore, the definition should be made based on the contents throughout the specification.

2 is a cross-sectional view showing a first embodiment of a photoelectric conversion module of the present invention.

As shown therein, the flexible printed circuit board 100 having the grooves 105 formed thereon, and the flexible IC substrate 110 having one end bent into the grooves 105 formed on the printed circuit board 100. And an optical element array 120 formed on an upper portion of the flexible IC substrate 110 that is bent into the groove 105, and embedded in the printed circuit board 100, and one end thereof is optically connected to the optical element array 120. The semiconductor chip 140 includes an optical waveguide array 130 and a semiconductor chip 140 formed on the flexible IC substrate 110 and including a driving circuit for driving the optical element array 120.

Here, the printed circuit board 100 includes a single-sided printed circuit board having wiring formed only on one surface of an insulating substrate, a double-sided printed circuit board having wiring formed on both sides of the insulating substrate, and a multilayer printed circuit board that is wired in multiple layers. Board: MLB) can be used, and multilayer printed circuit boards are mainly used due to the recent increase in demand for high density and miniaturized circuits.

The multilayer printed circuit board further includes a layer capable of forming a wiring pattern in order to enlarge a wiring area. Specifically, the multilayer printed circuit board is divided into an inner layer and an outer layer.

A circuit pattern 107 such as a power supply circuit, a ground circuit, a signal circuit, or the like is formed in the inner layer, and an insulating layer is formed between the inner layer and the outer layer or between the outer layers. At this time, the wiring of each layer is connected using a via hole.

Grooves 105 are formed in a predetermined region of the printed circuit board 100. The grooves 105 are formed with the optical element array 120 when the flexible IC substrate 110 is bent into the grooves 105. The optical waveguide array 130 is formed by adjusting the depth so that the optical waveguide array 130 is positioned at the same position.

The flexible IC substrate 110 is used as an intermediate medium that allows the semiconductor chip 140 to be electrically connected to the printed circuit board 100 easily.

That is, the semiconductor chip 140 has a large number of electrodes and an electrode spacing of only a few tens of micrometers, so that the semiconductor chip 140 can be directly bonded to the printed circuit board 100, resulting in a complicated structure of the printed circuit board 100 and a significant increase in cost. In order to prevent this, the semiconductor chip 140 and the printed circuit board 100 are electrically connected between the semiconductor chip 140 and the printed circuit board 100 using the flexible IC substrate 110.

The printed circuit board 100 and the flexible IC substrate 110 are bonded and electrically connected by flip chip bonding using a solder ball 101 and a bump 102.

In this case, the bumps 102 are electrically connected to the circuit patterns 107 formed on the inner layer of the printed circuit board 100, respectively.

Bonding between the printed circuit board 100 and the IC substrate 110 may be performed by a wire bonding method using a bonding wire as well as a flip chip bonding method, and may be performed by using the flip chip bonding and the wire bonding method. It may be.

One end of the flexible IC substrate 110 is bent into the groove 105 of the printed circuit board.

The optical device array 120 is formed on the flexible IC substrate 110 that is bent into the groove 105 of the printed circuit board, and is driven under the control of the semiconductor chip 140 to convert an electrical signal into an optical signal or Convert the optical signal into an electrical signal.

According to the present invention, the optical device array 120 is formed on the flexible IC substrate 110 bent into the groove 105 of the printed circuit board, thereby the optical device array 120 and the optical waveguide array 130 Butt coupled can be made, thereby improving the optical connection efficiency.

The optical device array 120 includes a light receiving device or a light emitting device, for example, a vertical cavity surface emitting laser (VCSEL), a light emitting diode (LED), a photo diode (PD), and the like, which are arranged on the same plane. Has a form.

The optical device array 120 is bonded to the upper portion of the flexible IC substrate 110, wherein the bonding between the flexible IC substrate 110 and the optical device array 120 is solder ball 111 and bump 112 By flip chip bonding method using).

Bonding between the flexible IC substrate 110 and the optical device array 120 may include not only the flip chip bonding method but also a wire bonding method using a bonding wire and a combination of the flip chip bonding and the wire bonding method. Can be done.

The optical waveguide array 130 is formed by being embedded in the printed circuit board 100, and has an optical waveguide arranged on the same plane as M × N. The optical waveguide of the optical waveguide array 130 The waveguide has the same arrangement as that of the photons of the optical element array 120.

The optical waveguide array 130 is bonded to the optical element array 120, wherein a light transmissive epoxy 125 is interposed between the optical element array 120 and the optical waveguide array 130 and bonded to the optical element array 120. Each of the optical waveguides of the waveguide array 130 is connected in a one-to-one correspondence with each optical element of the optical element array 120.

Here, the light transmissive epoxy 125 has a refractive index similar to that of the optical waveguide of the optical waveguide array 130, and preferably uses a polymer-based epoxy having good light transmittance at the wavelength of use of the optical element array 120.

For example, the light transmissive epoxy 125 has a refractive index of 1.4 to 1.6, it is preferable that the epoxy having a light transmittance of 80 to 95% at the wavelength of the light emitted from the optical element array 120.

The semiconductor chip 140 is used to drive the optical device array 120, and the semiconductor chip 140 includes a driving circuit for driving the optical device array 120.

The semiconductor chip 140 generates a control signal to the optical device array 120 to convert an electrical signal into an optical signal or an optical signal into an electrical signal.

The semiconductor chip 140 is bonded to the upper portion of the flexible IC substrate 110 through the solder balls 111 and the bumps 112. The semiconductor chip 140 may be bonded by a wire bonding method as well as the flip chip bonding method. Flip chip bonding and wire bonding may be used in a mixed manner.

In addition, an epoxy 150 is filled between the printed circuit board 100 and the flexible IC substrate 110 and between the flexible IC substrate 110 and the semiconductor chip 140, and the groove 105 of the printed circuit board is filled. The epoxy 150 is filled around the flexible IC substrate 110 and the optical device array 120.

The epoxy 150 serves to relieve stress caused by the difference in thermal expansion coefficient between the components when the external temperature changes, and to maintain the bonding state between the components.

In the present invention, a protective resin (not shown) surrounding the semiconductor chip 140 may be further formed on the flexible IC substrate 110 to protect the semiconductor chip 140 from an external environment.

As described above, the present invention forms a groove 105 in the printed circuit board 100 and allows one end of the flexible IC substrate 110 to be bent into the groove 105, and the light on the curved flexible IC substrate 110. By forming the device array 120 to be directly bonded to the optical waveguide array 130, it is possible to improve the optical coupling efficiency between the optical device and the optical waveguide.

That is, in the present invention, since the distance between the optical element and the optical waveguide can be maintained within several tens of micrometers, the optical coupling efficiency is superior to that of the conventional photoelectric conversion module.

In addition, the optical coupling efficiency is improved between the optical element array 120 and the optical waveguide array 130 by using a light transmissive epoxy 125 having a similar refractive index with the optical waveguide and having good light transmittance at the wavelength of use of the optical element array. You can improve further.

In addition, in the present invention, since the optical connection between the optical element and the optical waveguide is made on the same plane between the optical waveguides having the same arrangement as that of the optical element, the multi-channel optical connection can be easily made, and thus the optical design can be facilitated. Can be.

On the other hand, as shown in Figure 3, the printed circuit board 100 to form a space portion 106 penetrating the printed circuit board 100, the flexible IC substrate of the portion where the optical element array 120 is bonded ( After bending the 110 to the space portion 106, the optical device array 120 and the optical waveguide array 130 are aligned and bonded to each other, and the flexible IC substrate 110 and the optical device are connected to the space 106. The epoxy 120 may be filled to surround the array 120.

4 is a flowchart illustrating a method of manufacturing a photoelectric conversion module of the present invention.

As shown in the drawing, first, the optical device array 120 and the semiconductor chip 140 are bonded to the upper portion of the flexible IC substrate 110 (S 100).

That is, the flexible IC substrate 110 is placed on a plate, and both ends of the flexible IC substrate 110 are fixed with fixing jigs, and then the optical device array 120 and the semiconductor chip are placed on the flexible IC substrate 110. 140 is bonded.

Here, the optical element array 120 is an optical waveguide array 130 embedded in the printed circuit board 100 when one end of the flexible IC substrate 110 is bent into the groove 105 of the printed circuit board 100. ) Is bonded to one end of the flexible IC substrate 110 so as to be positioned at a position corresponding to the < RTI ID = 0.0 >

In this case, the optical device array 120 and the semiconductor chip 140 may be bonded through a flip chip bonding method using solder balls and bumps or a wire bonding method using bonding wires.

Next, the groove 105 is formed in the printed circuit board 100 (S 110).

The groove 105 of the printed circuit board is light bonded to an upper portion of the flexible IC substrate 110 that is bent into the groove 105 when one end of the flexible IC substrate 110 is bent into the groove 105. The element array 120 is formed by adjusting depth and width so that the device array 120 is positioned at a position corresponding to the optical waveguide array 130 embedded in the printed circuit board 100.

Subsequently, one end of the flexible IC substrate, that is, the portion where the optical device array 120 is bonded, is bent into the groove 105 of the printed circuit board, and then the optical device array 120 and the optical waveguide array 130 are disposed. Bonding (S 120).

The optical element array 120 has a shape in which the light receiving element or the light emitting elements are arranged on the same plane M × N, the optical waveguide array 130 is an optical waveguide of the optical element of the optical element array 120 They are formed in the same arrangement as the one-to-one optical connection with the photons of the optical device array 120.

Here, a light transmissive epoxy 125 is interposed between the optical element array 120 and the optical waveguide array 130, and the optical element array 120 and the optical waveguide array 130 are formed by the light transmissive epoxy 125. It is bonded and optically connected.

Meanwhile, the optical device array 120 and the optical waveguide array 130 are optically connected, and the flexible IC substrate 110 is bonded onto the printed circuit board 100 through flip chip bonding or wire bonding.

Subsequently, the flexible IC substrate 110 is filled in the groove 105 of the printed circuit board and the epoxy 150 is filled to surround the flexible IC substrate 110 and the optical device array 120 to bond and fix the flexible IC substrate 110 to the groove 105. The epoxy 150 is filled between the printed circuit board 100 and the flexible IC substrate 110 and between the flexible IC substrate 110 and the semiconductor chip 140 (S 130).

5 is a cross-sectional view showing a third embodiment of a photoelectric conversion module of the present invention.

As shown in the drawing, the printed circuit board 200 having the first grooves 203 and the second grooves 206 formed thereon, and formed on the printed circuit board 200 and having one end thereof as the first groove 203. A first optical element array formed on the flexible IC substrate 210 that is bent and the other end is curved by the second groove 206 and the flexible IC substrate 210 that is curved by the first groove 203. And a second optical element array 230 formed on the flexible IC substrate 210 that is bent into the second groove 206 and the printed circuit board 200, and one end of which is embedded in the first optical element array 230. A first optical waveguide array 240 optically connected to the optical element array 220 and a second optical waveguide embedded in the printed circuit board 200 and having one end optically connected to the second optical element array 230. A driving circuit formed on the array 250 and the flexible IC substrate 210 to drive the first optical device array 220 and the second optical device array 230. It is configured to include a semiconductor chip 260 is embedded.

Here, the first optical device array 220 and the first optical waveguide array 240 are bonded to each other with a first light transmissive epoxy 225 interposed therebetween, and the second optical device array 230 and the second light are interposed therebetween. The waveguide array 250 is bonded with a second light transmissive epoxy 235 interposed therebetween.

In addition, an epoxy 270 is filled between the printed circuit board 200 and the flexible IC substrate 210 and between the flexible IC substrate 210 and the semiconductor chip 260. An epoxy 270 is filled in the 203 and the second groove 206 to surround the flexible IC substrate 210, the first optical device array 220, and the second optical device array 230.

Although the present invention has been described in detail with reference to exemplary embodiments above, those skilled in the art to which the present invention pertains can make various modifications to the above-described embodiments without departing from the scope of the present invention. I will understand.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

As described above, according to the present invention, a groove is formed in the printed circuit board, and one end of the flexible IC substrate having the optical device array is bent in the groove of the printed circuit board, and then embedded in the optical device array and the printed circuit board. The optical coupling efficiency can be improved by allowing the arrayed optical waveguide arrays to be directly connected.

In the present invention, since the optical connection between the optical element and the optical waveguide is made on the same plane between the optical waveguides having the same arrangement as that of the optical element, the multi-channel optical connection is easily made, and thus the optical design can be easily performed. Can be.

Claims (11)

A grooved printed circuit board; A flexible IC substrate formed on the printed circuit board and having one end bent into the groove; An optical element array formed on the flexible IC substrate of the bent portion; An optical waveguide array buried in the printed circuit board and having one end optically connected to the optical element array in the groove; An epoxy filled in the groove of the printed circuit board surrounding the flexible IC substrate and the optical device array; And And a semiconductor chip formed on an upper portion of the flexible IC substrate and including a driving circuit for driving the optical element array. The method of claim 1, And the optical device array is formed on the flexible IC substrate bent into the groove by flip chip bonding or wire bonding. The method of claim 1, And the semiconductor chip is formed on the flexible IC substrate by flip chip bonding or wire bonding. The method according to any one of claims 1 to 3, And an optically transmissive epoxy interposed between the optical element array and the optical waveguide array. The method of claim 4, wherein The optical device array is a photoelectric conversion module, characterized in that the light emitting device or the light receiving device is arranged in the form of M × N. The method of claim 5, The optical waveguide array has an optical waveguide is arranged in the form of M × N, the optical waveguide is optically connected in a one-to-one correspondence with the optical element of the optical element array. The method of claim 4, wherein The light transmissive epoxy has a refractive index of 1.4 ~ 1.6, the photoelectric conversion module, characterized in that the epoxy having a light transmittance of 80 to 95% at the wavelength of the light emitted from the optical device. The method according to any one of claims 1 to 3, And a protective resin surrounding the semiconductor chip on the flexible IC substrate. Forming a semiconductor chip on the flexible IC substrate, and forming an optical element array driven by the semiconductor chip on one end of the flexible IC substrate; Forming a groove in one end of the flexible IC substrate having the optical element array formed thereon in a printed circuit board; The flexible IC substrate is bonded to the printed circuit board, the portion in which the optical device array of the flexible IC substrate is formed is bent into the groove of the printed circuit board, and then embedded in the optical device array and the printed circuit board. Bonding the arrayed optical waveguide arrays to be optically connected; And And enclosing the flexible IC substrate and the optical element array in the groove of the printed circuit board to charge the epoxy. The method of claim 9, The optical device array and the optical waveguide array is a manufacturing method of a photoelectric conversion module, characterized in that the bonding is interposed through the light transmitting epoxy. The method of claim 9 or 10, After bonding the semiconductor chip on the flexible IC substrate, And forming a protective resin surrounding the semiconductor chip on the flexible IC substrate.

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