TWM671514U - Optical connection module - Google Patents

Abstract

An optical connection module includes a circuit substrate, an optical fiber, a transimpedance amplifier and a photoelectric conversion element. The optical fiber is disposed on the circuit substrate and includes a transmission end. The transimpedance amplifier is disposed on the circuit substrate and is electrically connected to the circuit substrate, wherein the transimpedance amplifier is flip-chip packaged onto the circuit substrate. The photoelectric conversion element contacts the transimpedance amplifier and is coupled with the transmission end. The photoelectric conversion element is disposed between the transimpedance amplifier and the transmission end to convert an optical signal into an electrical signal and then transmits it to the transimpedance amplifier.

Description

Optical connection module

The novel invention relates to an electronic component, and in particular to an optical connection module.

As communications applications become more widespread (such as virtual reality, the Internet of Things, high-performance computing, and artificial intelligence and machine learning (AI/ML)), data transmission rates are gradually increasing. Networks and data centers around the world are also facing requirements for higher bandwidth, lower latency, and lower signal loss.

Nowadays, optical fiber has been widely used in data transmission over different distances. Plug-in optical transceivers have the advantages of easy replacement, modularity, and the ability to increase the bandwidth density between devices and components. However, as the signal transmission volume requirements increase dramatically, the increase in signal frequency is more likely to increase high-frequency loss, resulting in excessive noise, signal distortion, and reduced transmission efficiency.

The novel invention provides an optical connection module, which can effectively reduce the attenuation and distortion during signal transmission and can also provide a better optical coupling effect.

An embodiment of the present invention provides an optical connection module, including a circuit substrate, an optical fiber array, a transimpedance amplifier and an optoelectronic conversion element. The optical fiber array is arranged on the circuit substrate and includes a transmission end. The transimpedance amplifier is arranged on the circuit substrate and electrically connected to the circuit substrate, wherein the transimpedance amplifier is flip-chip packaged on the circuit substrate. The optoelectronic conversion element contacts the transimpedance amplifier and is coupled to the transmission end, and the optoelectronic conversion element is arranged between the transimpedance amplifier and the transmission end to convert an optical signal into an electrical signal and transmit it to the transimpedance amplifier.

Based on the above, in the optical connection module of the present invention, the photoelectric conversion element coupled to the transmission end of the optical fiber array is directly in contact with the transimpedance amplifier, which can also be understood as the flip chip package of the photoelectric conversion element on the transimpedance amplifier. When the photoelectric conversion element converts the optical signal emitted by the transmission end into an electrical signal, the electrical signal can be transmitted to the transimpedance amplifier without unnecessary wire bonding or circuits. In this way, the transmission path of the electrical signal can be shortened and the medium type of the channel is single, so that the high-frequency electrical loss in the process of transmitting the electrical signal to the transimpedance amplifier can be reduced, effectively improving the transmission quality of the high-frequency signal of the optical connection module. In addition, in the optical connection module of the present invention, the transimpedance amplifier is flip-chip packaged on the circuit substrate, so the density of the conductive path in the circuit substrate can be increased, the volume and thickness of the circuit substrate can be reduced, the electrical signal transmission path is shortened, and it is also beneficial to reduce the high-frequency loss of the circuit substrate.

In order to make the above features and advantages of the present invention more clearly understood, an embodiment is given below and described in detail with reference to the accompanying drawings.

As used herein, "about", "approximately", "substantially", or "substantially" include the stated value and the average value within an acceptable deviation range of a particular value determined by a person of ordinary skill in the art, taking into account the measurement in question and the specific amount of error associated with the measurement (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or, for example, within ±30%, ±20%, ±15%, ±10%, ±5%. Furthermore, as used herein, "about", "approximately", "substantially", or "substantially" can select a more acceptable deviation range or standard deviation depending on the measured property, cutting property or other property, and can apply to all properties without using one standard deviation.

In the accompanying drawings, the thickness of layers, films, panels, regions, etc., is exaggerated for clarity. It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another element, it can be directly on or connected to another element, or intermediate elements may also exist. Conversely, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intermediate elements. As used herein, "connected" may refer to physical and/or electrical connections.

Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and description to represent the same or similar parts.

FIG1 is a schematic diagram of the structure of an optical connection module of an embodiment of the present invention. FIG2 is a three-dimensional diagram of the optical connection module of FIG1. FIG3 is an exploded diagram of the optical connection module of FIG1. Please refer to FIG1, FIG2 and FIG3 simultaneously. The optical connection module 10A includes a circuit substrate 100, an optical fiber array 110, a transimpedance amplifier 120 and a photoelectric conversion element 130. The optical fiber array 110 is arranged on the circuit substrate 100 and includes a transmission end TE, which is suitable for transmitting a coded optical signal for information transmission, but is not limited thereto. The transimpedance amplifier 120 is arranged on the circuit substrate 100 and is electrically connected to the circuit substrate 100. In the relative position of each component, in the third direction D3 (which can also be understood as the thickness direction of the optical connection module 10A), the photoelectric conversion element 130 is arranged between the transimpedance amplifier 120 and the transmission end TE of the optical fiber array 110 to convert the optical signal emitted by the transmission end TE into an electrical signal and transmit it to the transimpedance amplifier 120.

The circuit substrate 100 may be a printed circuit board (PCB) or a flexible circuit board (FCB), but the present invention is not limited thereto. In some embodiments, the circuit substrate 100 may be any one of a multi-layer PCB, a high-density interconnector PCB (HDI PCB) or a high-frequency printed circuit board (HF PCB), but the present invention is not limited thereto. Specifically, when the circuit substrate 100 is a high-frequency printed circuit board, it may have a smaller relative permittivity (Dk) and a lower dissipation factor (Df), so that the high-frequency loss of the optical connection module 10A may be lower.

The optical fiber array 110 may include a plurality of optical fibers 111 and an interface 112. For example, FIG. 2 schematically illustrates an embodiment in which the optical fiber array 110 includes four optical fibers 111, and the four optical fibers 111 are arranged side by side in a first direction D1, and each optical fiber 111 extends in a second direction D2; and FIG. 3 illustrates an interface 112 connected to the plurality of optical fibers 111, and in the second direction D2, the transmission end TE and the interface 112 are respectively located at two ends of the optical fiber 111. In this document, the first direction D1, the second direction D2, and the third direction D3 may be different from each other, for example, any two of the first direction D1, the second direction D2, and the third direction D3 may be substantially perpendicular to each other, but this is not limited thereto.

Furthermore, in some embodiments, the number of optical fiber arrays 110 may be two, so the number of optical fibers 111 of the optical connection module 10A and the number of corresponding transmission terminals TE may be eight, that is, the optical connection module 10A may be an eight-channel small form factor pluggable package module (Octal Small Formfactor Pluggable, OSFP), but the present invention is not limited thereto. On the other hand, the optical fiber 111 may be a single-mode fiber, and further includes a core and a cladding layer covering the core (both not shown). The optical fiber 111 may also be a multi-mode fiber, and further includes an optical waveguide of the core, a cladding layer covering the optical waveguide, a buffer layer, and a jacket (both not shown), but the present invention is not limited thereto. The core material of the optical fiber 111 may include plastic, glass, silicon dioxide or a composite material thereof or other materials, but the present invention is not limited thereto. The wavelength of the optical signal transmitted by the optical fiber 111 may be 1271 nanometers (nm), 1291 (nm), 1311 (nm), 1331 (nm), etc. or other wavelength ranges, but the present invention is not limited thereto.

The photoelectric conversion element 130 may be a photodiode, and is used to couple with the transmission end TE of the optical fiber 111. For example, the photoelectric conversion element 130 may be spaced apart from the transmission end TE, and the transmission end TE and the photoelectric conversion element 130 may be connected by optical transparent glue or a connector (not shown), but the present invention is not limited thereto. The photoelectric conversion element 130 is used to convert the optical signal sent by the transmission end TE into an electric current signal (e.g., photocurrent).

On the other hand, in the embodiment where the number of optical fibers 111 is multiple (e.g., four or eight), the number of photoelectric conversion elements 130 corresponding to the multiple transmission ends TE may also be multiple (e.g., four or eight). In addition, in the third direction D3, the multiple photoelectric conversion elements 130 may also be overlapped with the multiple transmission ends TE, respectively, but the present invention is not limited thereto.

The transimpedance amplifier 120 (TIA) is used to convert the above-mentioned current signal into a voltage signal and amplify it. The transimpedance amplifier 120 can be an integrated circuit (IC) and is directly disposed on the upper surface 100S of the circuit substrate 100. In the present embodiment, the transimpedance amplifier 120 is flip-chip packaged on the circuit substrate 100. For example, the optical connection module 10A can further include a plurality of leads 121, which electrically connect the transimpedance amplifier 120 to the circuit substrate 100, wherein the leads 121 are located between the transimpedance amplifier 120 and the circuit substrate 100. In one embodiment, the pins 121 can be directly electrically connected to the pads (not shown) on the upper surface 100S of the circuit substrate 100, that is, the pins 121 contact the pads, but the present invention is not limited thereto. In some embodiments, the circuit substrate 100 can be manufactured using a modified semi-additive process (mSAP), and the transimpedance amplifier 120 is flip-chip packaged on the circuit substrate 100. Therefore, the density of the conductive path in the circuit substrate 100 can be increased, the volume and thickness of the circuit substrate 100 can be reduced, the electrical signal transmission path is shortened, and the high-frequency loss of the circuit substrate 100 is also reduced.

It is particularly noted that in the present invention, the photoelectric conversion element 130 is directly in contact with the transimpedance amplifier 120. For example, in the optical connection module 10A, the photoelectric conversion element 130 is directly disposed on the side of the transimpedance amplifier 120 facing the upper surface 100S. From another perspective, the pins 121 of the photoelectric conversion element 130 and the transimpedance amplifier 120 are both located on the same side of the transimpedance amplifier 120. Since the photoelectric conversion element 130 is not electrically connected to the transimpedance amplifier 120 via wire bonding technology (it can also be understood that the photoelectric conversion element 130 is flip-chip packaged on the transimpedance amplifier 120), the pin density of each chip (such as the transimpedance amplifier 120) on the circuit substrate 100 can be improved. Furthermore, omitting the wires and soldering materials for wire bonding can reduce unnecessary interface reflections, energy loss, and shorten the channel length, so that when the electrical signal is transmitted from the photoelectric conversion element 130 to the transimpedance amplifier 120, the high-frequency loss and noise of the electrical signal can be effectively reduced. Therefore, the electrical performance of the optical connection module 10A can be enhanced and the package volume can be reduced. Thereby, the electrical signal transmitted by the optical connection module 10A can have a higher signal-to-noise ratio (SNR), and the optical connection module 10A can provide a good photoelectric coupling effect in high-speed transmission.

In addition, the optical connection module 10A may further include a digital signal processor 140 (Digital signal processing, DSP). Specifically, the digital signal processor 140 is disposed on the circuit substrate 100. The digital signal processor 140 may be an integrated circuit and include a plurality of pins 141, and the pins 141 may be electrically connected to pads (not shown) of the circuit substrate 100 to receive required electrical energy or transmit electrical signals through the circuit substrate 100, but the present invention is not limited thereto. The digital signal processor 140 may convert the voltage signal generated by the transimpedance amplifier 120 into a digital signal, and transmit the converted digital signal to the circuit substrate 100. Finally, the digital signal can be transmitted to a server or a computer (not shown) via the gold finger 101 of the circuit substrate 100 .

Furthermore, the circuit substrate 100 may further include a redistribution layer 150, and the digital signal processor 140 is electrically connected to the transimpedance amplifier 120 via the redistribution layer 150. Specifically, in the second direction D2, the two opposite ends of the redistribution layer 150 may be electrically connected to the pin 121 and the pin 141, respectively. The redistribution layer 150 may be a high-frequency trace on the circuit substrate 100, for example, the redistribution layer 150 may be a straight line or a circular arc at a turning point, and the length of the redistribution layer 150 may be shorter. Thus, after the photoelectric conversion element 130 converts the optical signal emitted from the transmission end TE into an electrical signal, the electrical signal can be sequentially transmitted through the photoelectric conversion element 130, the transimpedance amplifier 120, the pin 121, the redistribution layer 150, and the pin 141 to the digital signal processor 140 for corresponding signal processing.

In some embodiments, the transmission capacity of the transmission end TE of each optical fiber 111 can be substantially 400 billion bits per second per channel (also understood as 400Gbps per channel; 400*10 ⁹ bits per second per channel). In the embodiment where the optical connection module 10A is an OSFP, the total transmission capacity of the optical connection module 10A can reach 3.2T (bps), but the present invention is not limited thereto.

Please refer to FIG. 1 again. In addition, in the present embodiment, the optical connection module 10A may include a blind hole TH, a portion of the photoelectric conversion element 130 is buried in the blind hole TH, and the optical fiber array 110 is further disposed in the circuit substrate 100. In detail, the transmission end TE of the optical fiber array 110 may emit an optical signal toward the third direction D3, so that the light receiving surface of the photoelectric conversion element 130 located in the blind hole TH may receive the optical signal. On the other hand, even if the photoelectric conversion element 130 has a relatively large thickness, the design of the blind hole TH may be used to create a space for accommodating the photoelectric conversion element 130, so that the assembly margin of each component in the optical connection module 10A may be improved, and it is also beneficial to fix the photoelectric conversion element 130 on the circuit substrate 100.

Please refer to Figure 3 again. The optical connection module 10A may further include a shell for protecting each component. For example, the optical connection module 10A may include a first shell 160A and a second shell 160B. The first shell 160A is disposed on the circuit substrate 100, and the circuit substrate 100 is disposed between the first shell 160A and the second shell 160B. The first shell 160A and the second shell 160B may form a housing space so that the circuit substrate 100 (and the aforementioned electronic components) are located in the housing space. In the second direction D2, the first shell 160A and the second shell 160B may also have two opposite openings to expose the interface 112 and the gold finger 101, so that the optical connection module 10A can receive optical signals and transmit electrical signals, but the present invention is not limited to this.

Other embodiments are listed below to illustrate the present invention in detail, wherein the same components are marked with the same symbols, and the description of the same technical content is omitted. For the omitted parts, please refer to the above embodiments, and no further description is given below.

FIG4 is a schematic diagram of the structure of an optical connection module of another embodiment of the present invention. FIG5 is a three-dimensional diagram of the optical connection module of FIG4. FIG6 is an exploded diagram of the optical connection module of FIG4. Please refer to FIG4, FIG5 and FIG6 simultaneously. The optical connection module 10B is similar to the aforementioned optical connection module 10A, and the main difference is that the optical fiber array 110 of the optical connection module 10B is arranged on the upper surface 100S. For example, in the thickness direction of the circuit substrate 100, the circuit substrate 100, the transimpedance amplifier 120, the photoelectric conversion element 130 and the transmission end TE of the optical fiber 111 are arranged in sequence.

In detail, in the present embodiment, the photoelectric conversion element 130 is disposed on a side of the transimpedance amplifier 120 that is opposite to the pin 121. Or from another perspective, in the third direction D3, the pin 121 and the photoelectric conversion element 130 are respectively located on opposite sides of the transimpedance amplifier 120. The photoelectric conversion element 130 can also contact the transimpedance amplifier 120 by means of a flip chip package. For example, in the present embodiment, the transimpedance amplifier 120 can also include a conductive via 120T, and the photoelectric conversion element 130 is electrically connected to the transimpedance amplifier 120 via the conductive via 120T. Therefore, after the optical signal emitted by the optical fiber array 110 is transmitted to the photoelectric conversion element 130 via the transmission end TE, the photoelectric conversion element 130 can convert the optical signal into an electrical signal (e.g., a current signal) and sequentially transmit it to the conductive via 120T, the transimpedance amplifier 120, the pin 121, the redistribution layer 150, and the digital signal processor 140. The digital signal processor 140 converts the voltage signal into a digital signal and then transmits it to the gold finger 101 to transmit the digital signal outside the optical connection module 10B.

On the other hand, the optical connection module 10B may further include a fixing member 170 for fixing the optical fiber array 110 on the circuit substrate 100. For example, in the third direction D3, the fixing member 170 may be disposed between the optical fiber array 110 and the circuit substrate 100 to prevent the optical fiber array 110 from being misaligned on the circuit substrate 100, so as to ensure the structural strength and stability of the optical connection module 10B. In some implementations, the fixing member 170 may be a welding material, an adhesive layer, or a pressure sensitive adhesive (PSA), but the present invention is not limited thereto.

In summary, in the optical connection module of the present invention, the photoelectric conversion element coupled to the transmission end of the optical fiber array is directly in contact with the transimpedance amplifier, which can also be understood as the flip chip package of the photoelectric conversion element on the transimpedance amplifier. When the photoelectric conversion element converts the optical signal emitted by the transmission end into an electrical signal, the electrical signal can be transmitted to the transimpedance amplifier without unnecessary wire bonding or circuits. In this way, the transmission path of the electrical signal can be shortened and the medium type of the channel is single, so that the high-frequency electrical loss in the process of transmitting the electrical signal to the transimpedance amplifier can be reduced, effectively improving the transmission quality of the high-frequency signal of the optical connection module. In addition, in the optical connection module of the present invention, the transimpedance amplifier is flip-chip packaged on the circuit substrate, so the density of the conductive path in the circuit substrate can be increased, the volume and thickness of the circuit substrate can be reduced, the electrical signal transmission path is shortened, and it is also beneficial to reduce the high-frequency loss of the circuit substrate.

Although the novel creation has been disclosed as above by way of embodiments, they are not intended to limit the novel creation. Any person with ordinary knowledge in the relevant technical field may make slight changes and modifications without departing from the spirit and scope of the novel creation. Therefore, the protection scope of the novel creation shall be subject to the scope defined in the attached patent application.

10A, 10B: Optical connection module 100: Circuit board 100S: Top surface 101: Gold finger 110: Fiber array 112: Interface 111: Fiber 120: Transimpedance amplifier 120T: Conductive hole 121, 141: Pins 130: Photoelectric conversion element 140: Digital signal processor 150: Rewiring layer 160A: First shell 160B: Second shell 170: Fixing part D1: First direction D2: Second direction D3: Third direction TE: Transmission end TH: Blind hole

Figure 1 is a structural schematic diagram of an optical connection module of an embodiment of the present invention. Figure 2 is a three-dimensional diagram of the optical connection module of Figure 1. Figure 3 is an exploded diagram of the optical connection module of Figure 1. Figure 4 is a structural schematic diagram of an optical connection module of another embodiment of the present invention. Figure 5 is a three-dimensional diagram of the optical connection module of Figure 4. Figure 6 is an exploded diagram of the optical connection module of Figure 4.

10A: Optical connection module

100: Circuit board

100S: Upper surface

110: Fiber optic array

111: Optical fiber

120: Transimpedance amplifier

121: Pin

130: Photoelectric conversion element

150: Rewiring layer

D1: First direction

D2: Second direction

D3: Third direction

TE: Transmission terminal

TH: Blind hole

Claims (12)

An optical connection module includes: a circuit substrate; an optical fiber array, disposed on the circuit substrate and including a transmission end, suitable for transmitting an optical signal; a transimpedance amplifier, disposed on the circuit substrate and electrically connected to the circuit substrate, wherein the transimpedance amplifier is flip-chip packaged on the circuit substrate; and an optoelectronic conversion element, contacting the transimpedance amplifier and coupled to the transmission end, the optoelectronic conversion element being disposed between the transimpedance amplifier and the transmission end to convert the optical signal into an electrical signal and then transmit it to the transimpedance amplifier. The optical connection module as described in claim 1 also includes a digital signal processor disposed on the circuit substrate. An optical connection module as described in claim 2, wherein the circuit substrate further includes a redistribution layer, and the digital signal processor is electrically connected to the transimpedance amplifier via the redistribution layer. As described in claim 1, the optical connection module, wherein the circuit substrate further includes a blind hole, the photoelectric conversion element is partially buried in the blind hole, and the optical fiber array is further arranged in the circuit substrate. The optical connection module as described in claim 1 further includes a plurality of pins for electrically connecting the transimpedance amplifier to the circuit substrate, wherein the pins are located between the transimpedance amplifier and the circuit substrate, and the photoelectric conversion element and the pins are located on the same side of the transimpedance amplifier. An optical connection module as described in claim 1, wherein the circuit substrate, the transimpedance amplifier, the photoelectric conversion element and the transmission end are arranged in sequence in the thickness direction of the circuit substrate. The optical connection module as described in claim 1 further includes a plurality of pins for electrically connecting the transimpedance amplifier to the circuit substrate, wherein the pins are located between the transimpedance amplifier and the circuit substrate, and the photoelectric conversion element and the pins are respectively located on opposite sides of the transimpedance amplifier. An optical connection module as described in claim 1, wherein the transimpedance amplifier further includes a conductive hole, and the photoelectric conversion element is electrically connected to the transimpedance amplifier via the conductive hole. An optical connection module as described in claim 1, wherein the number of the transmission ends is multiple, and the number of the photoelectric conversion elements is multiple and are respectively overlapped with the transmission ends. An optical connection module as described in claim 9, wherein the transmission capacity of the transmission end is substantially 400 billion bits/second/channel. An optical connection module as described in claim 10, wherein the number of the transmission ends is eight. The optical connection module as described in claim 1 further includes: a first housing disposed on the circuit substrate; and a second housing, wherein the circuit substrate is disposed between the first housing and the second housing.

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