Circuit board

A circuit board includes a plurality of insulators provided horizontally side by side and at least one first electric conductor. A first accommodating space is formed between two adjacent ones of the insulators, and each of the two adjacent ones of the insulators is provided with at least one fixing portion in the first accommodating space. The first electric conductor is accommodated in the first accommodating space, and is retained in the fixing portions of the two adjacent ones of the insulators only at two sides thereof. The first electric conductor in the circuit board is used to transmit signals and surrounded with air, and compared with the conventional circuit board in which signals are transmitted through a dielectric layer, a signal transmission effect with ultra-low signal attenuation can be achieved.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This non-provisional application claims priority to and the benefit of, pursuant to 35 U.S.C. § 119(a), patent application Serial No. CN201811056460.0 filed in China on Sep. 11, 2018. The disclosure of the above application is incorporated herein in its entirety by reference.

FIELD

The present invention relates to a circuit board, and in particular to a circuit board in which an electric conductor for transmitting signals is surrounded by air as a medium.

BACKGROUND

With the development of electronic technologies, transmission attenuation of a high frequency signal is mainly affected by a medium during transmission of an electrical signal. A fundamental reason thereof is that the high frequency signal is related to a dielectric constant of the medium, and a lower dielectric constant of a medium indicates better high frequency signal transmission. For conventional media, a liquid crystal polymer (LCP), Teflon or a pure adhesive with low relative permittivity are usually used as a substrate layer to wrap a signal line.

However, a dielectric loss of the foregoing materials is still relatively large, resulting in large signal attenuation of a transmission line of a circuit board made of these materials. In addition, Teflon and the LCP are special materials with high material costs. In addition, a conventional signal conductor is provided above or below a dielectric layer, and such arrangement thickens the circuit board and makes flexibility of the circuit board decrease.

Therefore, a heretofore unaddressed need to design a novel circuit board exists in the art to address the aforementioned deficiencies and inadequacies.

SUMMARY

The present invention is directed to a circuit board with better high frequency signal transmission.

In order to achieve the foregoing objective, the present invention adopts the following technical solutions:

A circuit board includes: a plurality of insulators, provided horizontally side by side, wherein a first accommodating space is formed between a first group of two adjacent ones of the insulators, and each of the first group of two adjacent ones of the insulators is provided with at least one fixing portion in the first accommodating space; and a first electric conductor accommodated in the first accommodating space, wherein the first electric conductor is retained in the fixing portions of the first group of two adjacent ones of the insulators only at two sides thereof.

In certain embodiments, each of the at least one fixing portion is formed by protruding from a side wall of a corresponding one of the insulators, and is provided with a recessed area in a horizontal direction, and the two sides of the first electric conductor are retained in the recessed areas of the fixing portions of the first group of two adjacent ones of the insulators such that an upper surface and a lower surface of the first electric conductor are attached to the fixing portion.

In certain embodiments, the first electric conductor is flat plate shaped, and the two sides of the first electric conductor are retained in the recessed area and seamlessly fill in the recessed area.

In certain embodiments, a gap is formed between each of the two sides of the first electric conductor and the corresponding side wall.

In certain embodiments, the first electric conductor is a signal conductor.

In certain embodiments, the circuit board further includes a second electric conductor. The second electric conductor is flat plate shaped, a second accommodating space is formed between a second group of two adjacent ones of the insulators to accommodate the second electric conductor, and at least one insulator of the second group of two adjacent ones of the insulators is different from each of the insulators in the first group of two adjacent ones of the insulators.

In certain embodiments, a plastic member wraps outside the second electric conductor.

In certain embodiments, a metal shell wraps outside the plastic member.

In certain embodiments, the circuit board further includes two shielding layers and two insulating layers, wherein one of the two shielding layers is provided above the insulators, the other of the two shielding layers is provided below the insulators, one of the two insulating layers is provided above the one of the two shielding layers, and the other of the two insulating layers is provided below the other of the two shielding layers.

In certain embodiments, each of an upper surface and a lower surface of the metal shell is in contact with a corresponding one of the shielding layers.

In certain embodiments, spaces are formed between an upper surface of the first electric conductor and the one of the two shielding layers and between a lower surface of the first electric conductor and the other of the two shielding layers.

In certain embodiments, the second electric conductor is a power supply conductor.

In certain embodiments, the second electric conductor is cylindrical shaped.

In certain embodiments, the circuit board is a flexible circuit board.

Compared with the related art, the circuit board according to certain embodiments of the present invention have the following beneficial effects:

In the circuit board, the insulators are provided horizontally side by side, and a first accommodating space is formed between the two adjacent ones of the insulators. The first electric conductor is accommodated in the first accommodating space and the two sides thereof are retained in the two adjacent fixing portions, and the remaining portion of the first electric conductor is exposed in the first accommodating space and is in contact with air in the first accommodating space. Therefore, the first electric conductor is used to transmit signals and surrounded with air, and compared with the conventional circuit board in which signals are transmitted through a dielectric layer, a signal transmission effect with ultra-low signal attenuation can be achieved.

DETAILED DESCRIPTION

As shown inFIG. 1toFIG. 7, a circuit board100according to certain embodiments of the present invention is a flexible circuit board, and the circuit board100can be electrically connected to an electrical component (not shown).

FIG. 1toFIG. 5show a circuit board100according to a first embodiment of the present invention. First, an X-axis direction is defined as a left-right direction, a Y-axis direction is defined as a front-rear direction, and a Z-axis direction is defined as a vertical direction. The circuit board100is substantially a circuit board100of a five-layer structure, which includes a plurality of insulators1. Each insulator1extends along the Y-axis direction to substantially form a cuboid. In other embodiments, the insulators1may also be in other feasible shapes, such as a cube shape. The insulators1are provided horizontally side by side along the X-axis direction, and a first accommodating space11is provided between a first group of two adjacent ones of the insulators1and a second accommodating space12is provided between a second group of two adjacent ones of the insulators1. The circuit board100includes a plurality of first accommodating spaces11and a plurality of second accommodating spaces12. Each first accommodating space11and each second accommodating space12are filled with air and extend along the Y-axis direction.

As shown inFIG. 1toFIG. 3, the two adjacent insulators1of the first group forming the first accommodating space11have a plurality of fixing portions13. Each fixing portion13is substantially in a semi-cylindrical shape. Each fixing portion13is formed by protruding from a side wall of each of the two adjacent insulators1toward the first accommodating space11, and the fixing portions13are symmetrical about a vertical plane on which a midpoint of the first accommodating space11lies. In other embodiments, the fixing portions13may further be in other feasible shapes. The fixing portions13may further be asymmetrically provided about the vertical plane on which the midpoint of the first accommodating space11lies. Each fixing portion13is provided with a recessed area131at a middle location thereof in the Z-axis direction. The recessed area131is horizontally provided in the X-axis direction, but is not provided to reach the side wall of the corresponding insulator1in the X-axis direction. In other embodiments, the recessed area131can further be provided to reach the side wall of the insulator1or even to extend into the side wall of the insulator1. The recessed area131is further not limited to being provided in a horizontal direction, and can further be arranged in an inclined direction.

As shown inFIG. 3andFIG. 4, the second accommodating space12is a space between the side walls of the two adjacent insulators1of the second group, and each of the side walls of the two adjacent insulators1of the second group is a smooth plane. The circuit board100further includes two shielding layers2and two insulating layers3. One of the two shielding layers2is provided above the insulators1, and the other of the two shielding layers2is provided below the insulators1. One of the two insulating layers3is provided above the one of the two shielding layers2, and the other of the two insulating layers3is provided above the other of the two shielding layers2. Each of shielding layers2is provided between the corresponding insulator1and a corresponding one of the insulating layers3. In addition, the planes on which the upper surface and the lower surface of the insulator1lie are parallel to the X-Y plane.

As shown inFIG. 1,FIG. 2, andFIG. 4, multiple electric conductors4are accommodated in the first accommodating spaces11and the second accommodating spaces12, and each electric conductor4is substantially flat plate shaped. The electric conductors4includes a plurality of first electric conductors41, a plurality of second electric conductors42, and a plurality of third electric conductors43. Each first electric conductor41is a high-speed signal conductor, and two adjacent ones of the first conductors41form a differential pair for transmitting a differential signal. Each second electric conductor42is a power supply conductor42, and each third electric conductor43is another functional conductor. Each of the third electric conductors43may be a grounding conductor, a low-speed signal conductor, a control conductor, or a preparatory conductor. The third electric conductors43can be adjusted and planned autonomously according to practical application conditions of the circuit board100. The first electric conductors41are one-to-one accommodated in the first accommodating spaces11, and the second electric conductors42are one-to-one accommodated in the second accommodating spaces12. Two sides of each first electric conductor41are retained in the recessed areas131of the fixing portions13, and upper surfaces and lower surfaces of the two sides of each first electric conductor41are seamlessly attached to upper surfaces and lower surfaces of the recessed areas131to form surface contacts. In addition, two ends of each first electric conductor41, that is, plate edges of the two sides of each first electric conductor41, are further seamlessly attached to side faces of the recessed areas131. Finally, a state of each first electric conductor41located in the recessed area131is that the space in the recessed area131is fully and seamlessly filled by the first electric conductor41.

As shown inFIG. 4andFIG. 5, in this case, each recessed area131is horizontally provided in the X-axis direction, but is not provided to reach the side wall of the corresponding insulator1in the X-axis direction. Therefore, a gap G is still formed between the corresponding plate edge of the first electric conductor41and the side wall of the insulator1. In addition, a space is further formed between each of the upper surface and the lower surface of the first electric conductor41and the corresponding shielding layer2.

As shown inFIG. 2andFIG. 4, a plastic member5wraps the second electric conductor42. The plastic member5is substantially rectangular. A metal shell6further wraps the plastic member5. The metal shell6is substantially rectangular. A left side and a right side of the metal shell6are respectively in contact with the side walls of the insulators1, and an upper surface and a lower surface of the metal shell6are both in contact with the shielding layers2. The remaining third electric conductor43is wrapped by the insulator1.

In the flexible circuit board100provided in the first embodiment of the present invention, each first electric conductor41, except for a retaining portion thereof, is exposed in the corresponding first accommodating space11and is in contact with air, and a dielectric constant of the air in the corresponding first accommodating space11is less than the dielectric constants of the Teflon, the LCP, the pure adhesive, or other conventional insulating materials. Therefore, the air replaces the Teflon, the LCP, the pure adhesive, or other conventional insulating materials to serve as a dielectric layer to wrap a signal line, such that a signal of the flexible circuit board100is transmitted in the air and is almost lossless, thus achieving signal transmission with ultra-low signal attenuation. In addition, the first accommodating spaces11and the second accommodating spaces12are provided between the insulators1, and the structural strength of the layer in which the insulators1are located may be further reduced, such that the flexibility thereof is better than that of the insulators1without providing with the first accommodating space11and the second accommodating space12. In addition, when the insulators1are made of the conventional Teflon or the LCP, manufacturing costs thereof are relatively high. When each first accommodating space11is provided between two adjacent insulators1of the first group and each second accommodating space12is provided between two adjacent insulators1of the second group, material consumption of the insulators1can further be reduced, thereby reducing production costs.

FIG. 6andFIG. 7show a circuit board100according to a second embodiment of the present invention. A difference between the second embodiment and the first embodiment exists in that the second electric conductor42is cylindrical shaped, the plastic member5wrapping the second electric conductor42is also cylindrical shaped, and a metal housing6wrapping the plastic member5is cylindrical shaped as well. For other structures thereof, reference can be made to the corresponding structures in the first embodiment. When the second electric conductor42is cylindrical shaped, a diameter of the second electric conductor42is relatively smaller in comparison to a horizontal length thereof when the second electric conductor42is flat plate shaped. Therefore, a distance between the second electric conductor42and an adjacent electric conductor4becomes greater. Since the second electric conductor42is a power supply conductor and the power supply conductor in the circuit board100has a relatively large signal interference with the electric conductor4around the power supply conductor, the distance between the second electric conductor42and the adjacent electric conductor4can be effectively increased when the second electric conductor42is cylindrical shaped, thereby reducing the signal interference.

In sum, the circuit board100according to certain embodiments of the present invention has the following beneficial effects:

(1) A conductive layer of the conventional circuit board structure is generally provided above a dielectric layer, and another dielectric layer is provided above the conductive layer. Therefore, the signal transmission of the conductive layer is mainly affected by the dielectric layers. A lower dielectric constant of a dielectric layer indicates a better signal transmission effect. However, dielectric constants of the dielectric layers made of conventional materials are greater than the dielectric constant of air. Therefore, in certain embodiments of the present invention, the insulators1of the circuit board100are provided horizontally side by side, the first accommodating space11is provided between the two adjacent insulators, and the first electric conductor41is retained in the fixing portions13only on two sides thereof. Most structures of the first electric conductor41are in contact with air in the first accommodating space11. Therefore, the first electric conductor41is used to transmit signals and surrounded by air to achieve a signal transmission effect with ultra-low signal attenuation.

(2) In the conventional circuit board, a dielectric layer can be made of the Teflon or the LCP, but the costs are high. In certain embodiments of the present invention, the insulators1of the circuit board100are provided horizontally side by side, and each first accommodating space11is provided between two adjacent insulators1of the first group and each second accommodating space12is provided between two adjacent insulators1of the second group, and at least one insulator1of the second group of two adjacent ones of the insulators1is different from each of the insulators1in the first group of two adjacent ones of the insulators1, such that a material usage of the insulators1can be reduced, and the signal transmission can be better. Therefore, the presence of the first accommodating space11and the second accommodating space12can further reduce the production costs. In addition, the circuit board100is a flexible circuit board100. Because of the presence of the first accommodating space11and the second accommodating space12, a layer in which the insulator1lies is a non-successive layer. Therefore, a structural strength of the layer is low, thereby improving the flexibility of the circuit board100.

(3) The conductive layer of the conventional circuit board structure is generally provided above the dielectric layer, while the electric conductors4of the circuit board100according to certain embodiments of the present invention are provided in the first accommodating spaces11and the second accommodating spaces12between the insulators1respectively, thereby reducing a thickness of the circuit board100, and saving the space to enable the circuit board100to potentially be capable of providing more additional structures, and meanwhile improving the flexibility of the circuit board100.