CN105430890A - Printed Circuit Boards and Mobile Terminals - Google Patents

Abstract

The invention discloses a printed circuit board, which comprises a first signal layer, a first substrate, a first reference layer, a second substrate and a second reference layer which are arranged in a stacked mode, wherein the first signal layer comprises at least one radio frequency signal line, the radio frequency signal line comprises a first section of line and a second section of line which are electrically connected, the width of the first section of line is smaller than that of the second section of line, the characteristic impedance of the first section of line refers to the first reference layer, the characteristic impedance of the second section of line refers to the second reference layer, and the characteristic impedance of the first section of line is equal to that of the second section of line. The loss of the radio frequency signal transmission on the printed circuit board is low. The invention also discloses a mobile terminal.

Description

Printed Circuit Boards and Mobile Terminals

technical field

The invention relates to the field of printed circuit boards, in particular to a printed circuit board for transmitting radio frequency signals and a mobile terminal.

Background technique

On large-scale printed circuit boards and packaging substrates, the signal wires used to electrically connect two components or two terminals must have the same line width so that when the electronic signal is transmitted between the signal wires, the characteristic impedance of the signal wire (characteristicimpedance) can remain unchanged, especially in high-speed and high-frequency signal transmission, it is necessary to use a good impedance matching design between the two ends to reduce the reflection caused by impedance mismatch, that is, to reduce the signal Insertion loss during transmission, and relatively increase the return loss during signal transmission to avoid affecting the quality of signal transmission. With the development of science and technology, more and more components are integrated on the printed circuit board. Under the demand of the era that requires the miniaturization of the printed circuit board, the layout density of the components on the printed circuit board is also increasing. At this time, in order to ensure the signal The isolation between traces reduces crosstalk, and the width of signal lines is limited, which also increases the loss of signals (such as radio frequency signals) passing through the signal lines.

Contents of the invention

The technical problem to be solved by the present invention is to provide a low-loss printed circuit board applied to radio frequency signal transmission and a mobile terminal using the printed circuit board.

In order to achieve the above object, the embodiment of the present invention adopts the following technical solutions:

In one aspect, a printed circuit board is provided, comprising a stacked first signal layer, a first substrate, a first reference layer, a second substrate, and a second reference layer, the first signal layer includes at least one radio frequency signal line, The radio frequency signal line includes a first section of line and a second section of line electrically connected, the width of the first section of line is smaller than the width of the second section of line, and the characteristic impedance of the first section of line refers to the first reference layer, so The characteristic impedance of the second section of line refers to the second reference layer, and the characteristic impedance of the first section of line is equal to the characteristic impedance of the second section of line.

Preferably, the first signal layer includes a first region and a second region, the density of pads on the first region is greater than the density of pads on the second region, and the first region of the radio frequency signal line A segment line is connected to the pad on the first area, and the second segment of the radio frequency signal line is connected to the pad on the second area.

Preferably, the first reference layer is a continuous copper foil layer covering the first signal layer, and the first reference layer is hollowed out at a position facing the second segment of line.

Preferably, the second reference layer is a continuous copper foil layer covering the first signal layer.

Preferably, the second reference layer is a discrete copper foil layer and covers at least the second segment of the line.

Preferably, the printed circuit board further includes a second signal layer located on the side of the second substrate away from the first reference layer, at least one signal line is arranged on the second signal layer, and the signal line is connected to the first reference layer. The second reference layers do not overlap.

Preferably, the radio frequency signal line further includes a third section of line, the third section of line is electrically connected to the end of the second section of line away from the first section of line, and the width of the third section of line is equal to the The width of the first section of lines, the third section of lines refer to the first reference layer.

Preferably, the printed circuit board further includes a third substrate and a third reference layer sequentially stacked on the side of the second reference layer facing away from the second substrate, and the radio frequency signal line further includes a third section of line, The third section of line is connected to the end of the second section of line away from the first section of line, the width of the third section of line is greater than the width of the second section of line, and the third section of line refers to the The third reference layer.

Preferably, the radio frequency signal line further includes a first pad and a second pad arranged at both ends of the first segment of the line, the first pad and the second pad are parallel to the first The dimension in the width direction of the segment line is larger than the width of the first segment line, and the characteristic impedance of the first pad and the characteristic impedance of the second pad refer to the second reference layer.

Preferably, the first substrate and the second substrate are flexible substrates.

In another aspect, a mobile terminal is also provided, including the printed circuit board as described in any one of the above items.

Compared with the prior art, the present invention has the following beneficial effects:

The width of the second segment of the printed circuit board of the present invention is larger than the width of the first segment of the circuit, since the increased width of the signal line can reduce signal loss, and the radio frequency signal line can be arranged more by the second segment Two-section line to reduce the loss of the entire signal line. At the same time, the widths of the first section of the radio frequency signal line and the second section of the line are different, so that the arrangement of the radio frequency signal line on the printed circuit board can be based on the components on the printed circuit board. The density of the device and the signal line density are used to flexibly set the width of the radio frequency signal line, which can not only ensure that the wiring of the radio frequency signal line on the printed circuit board is more flexible and diverse, but also ensure the isolation between adjacent radio frequency signal lines degree, reducing crosstalk. Further, since the distances between the first section of lines and the second section of lines and their respective reference layers are different, the distance between wider lines and corresponding reference layers is larger, so that the radio frequency signal lines can Ensure the continuity of impedance, realize impedance matching, avoid signal reflection, and ensure high-quality signal transmission.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the accompanying drawings used in the implementation will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some implementations of the present invention. As far as technical personnel are concerned, other drawings can also be obtained like these drawings without paying creative work.

FIG. 1 is a schematic top view structural diagram of a printed circuit board provided by an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional structure diagram of a printed circuit board provided by an embodiment of the present invention.

FIG. 3 is a schematic top view of another printed circuit board provided by an embodiment of the present invention.

FIG. 4 is a schematic top view of another printed circuit board provided by an embodiment of the present invention.

FIG. 5 is a schematic top view of yet another printed circuit board provided by an embodiment of the present invention.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention.

Please refer to FIG. 1 and FIG. 2 , an embodiment of the present invention provides a printed circuit board, including a stacked first signal layer 1, a first substrate 2, a first reference layer 3, a second substrate 4, and a second reference layer 5. The first signal layer 1 includes at least one radio frequency signal line, and the radio frequency signal line includes a first segment line 11 and a second segment line 12 electrically connected, and the width of the first segment line 1 is smaller than that of the second segment line The width of the line 2, the characteristic impedance of the first line 11 refers to the first reference layer 2, the characteristic impedance of the second line 12 refers to the second reference layer 5, the characteristic impedance of the first line 11 is equal to the The characteristic impedance of the second line 12.

It should be understood that the "electrical connection" refers to the electrical conduction between the first line 11 and the second line 12, and the radio frequency signal can be connected between the first line 11 and the second line. The transmission between the line segments 12 does not limit the line entity structure relationship between the first line segment 11 and the second line segment 12, such as direct connection or indirect connection. As shown in Figure 2, the dimensional relationship and positional relationship between the structures corresponding to the serial numbers 100, 200, 300, and 400 dotted line boxes in the figure do not limit the actual size and mutual positional relationship of the corresponding structures, but are only used to illustrate the present embodiment. The corresponding structure can realize electrical connection.

It should be understood that the above "reference layer" may be a ground plane or a power plane, which is used to provide a return path for the return signal. The above "radio frequency signal" means that when the electromagnetic wave frequency is lower than 100kHz, the electromagnetic wave will be absorbed by the surface and cannot form effective transmission. Once the electromagnetic wave frequency is higher than 100kHz, the electromagnetic wave can propagate in the air and pass through the ionization of the outer edge of the atmosphere. Layer reflection, forming long-distance transmission capability, we call the high-frequency electromagnetic wave with long-distance transmission capability radio frequency. The above-mentioned "characteristic impedance" is also called "characteristic impedance". It is not a DC resistance, but a concept in long-distance transmission. In the high-frequency range, during signal transmission, where the signal edge arrives, an instantaneous current will be generated between the signal line and the reference plane (power or ground plane) due to the establishment of an electric field. If the transmission line is isotropic, then as long as When the signal is being transmitted, there is always a current I, and if the output level of the signal is V, during the signal transmission process, the transmission line will be equivalent to a resistance, the size is V/I, and this equivalent resistance is called The characteristic impedance Z of the transmission line. During the transmission of the signal, if the characteristic impedance on the transmission path changes, the signal will be reflected at the node with discontinuous impedance.

In this embodiment, the width of the second section of line 12 is larger than that of the first section of line 11. Since the increased width of the signal line can reduce signal loss, the radio frequency signal line can be arranged more Two sections of lines 12 are used to reduce the loss of the entire signal line. At the same time, the widths of the first segment 11 and the second segment 12 of the radio frequency signal line are different, so that when the radio frequency signal line is arranged on the printed circuit board, it can be arranged according to the width of the printed circuit board. The density of components and parts and the density of signal lines are used to flexibly set the width of the radio frequency signal line, which can ensure that the wiring of the radio frequency signal line on the printed circuit board is more flexible and diverse, and also ensures that the space between adjacent radio frequency signal lines isolation and reduce crosstalk. Further, since the distance between the first section of line 11 and the second section of line 12 and their respective reference layers is different, the distance between the wider line and the corresponding reference layer is larger, so that the radio frequency signal The line can ensure the continuity of impedance, realize impedance matching, avoid signal reflection, and ensure high-quality signal transmission.

Further, as shown in FIG. 1 , the first signal layer includes a first region A and a second region B, and the density of pads on the first region A (as shown by black circles in FIG. 1 ) is greater than the The density of the pads on the second area B (as shown by the black square dots in Figure 1), the first section of the line 11 of the radio frequency signal line is connected to the pads on the first area A, so The second section of the radio frequency signal line is connected to the pad of B on the second region 12 . It can be seen that, the radio frequency signal line can flexibly set the width of each section of the line according to the density of component pins or pads on the first signal layer, and the routing density. It should be understood that the first area A and the second area B are not specifically referred to or limited to the parts shown in the box in FIG. The width of the lines is different. Thinner RF signal lines are arranged in areas with high pad density, and wider RF signal lines are arranged in areas with low pad density.

As a preferred embodiment of the present invention, please refer to FIG. 2, the first reference layer 3 is a continuous copper foil layer and covers the first signal layer 1, and the first reference layer 3 is facing the The position of the second section of line 12 is hollowed out. Further, the second reference layer 5 is a continuous ground copper foil layer and covers the first signal layer 1 . In this way, the characteristic impedance of the first section of line 11 refers to the first reference layer 3 , and the characteristic impedance of the second section of line 12 refers to the second reference layer 5 . The signal lines with different widths refer to different reference layers, so that the impedances of the first line 11 and the second line 12 are continuous.

Further, the first substrate 2 and the second substrate 4 are flexible substrates, so the printed circuit board is a flexible printed circuit board. It can be understood that the first substrate 2 and the second substrate 4 can also be rigid substrates, so that the printed circuit board has hardness and strength, and the first substrate 2 and the second substrate 4 can also be It is a combination of soft and hard boards, so that the printed circuit board has a wider range of applications.

Further, the radio frequency signal line also includes a third section of the line, the third section of the line is electrically connected to the end of the second section of the line 12 away from the first section of the line 11, and the width of the third section of the line is is equal to the width of the first section of lines, and the third section of lines refers to the first reference layer. In this way, the setting of the radio frequency signal line is more flexible and changeable.

As shown in FIG. 2, in this embodiment, the radio frequency signal line further includes a first pad 13 and a second pad 14 arranged at both ends of the first section of the line 11, the first pad 13 and the second pad 14 The size of the second pad 14 in the direction parallel to the width of the first section of line 11 is greater than the width of the first section of line 11, the characteristic impedance of the first pad 13 and the second pad 13 The characteristic impedances of 14 are all referred to the second reference layer 5 . The first reference layer 3 is hollowed out at the position facing the first pad 13 and the second pad 14 . This embodiment can ensure that the signal line part and the bonding pad part of the high-speed signal line keep impedance continuity, and avoid signal reflection. It should be understood that the above-mentioned embodiment is only an example, and in fact, the pads and signal lines passed through during the complete transmission of the radio frequency signal can be set according to the above-mentioned rule, so as to ensure the impedance continuity of the entire line.

As another preferred embodiment of the present invention, please refer to FIG. 3, the first reference layer 3 is a continuous copper foil layer and covers the first signal layer 1, and the first reference layer 3 is opposite to the The position of the second section of the line 12 is hollowed out. Further, the second reference layer 5 is a discrete copper foil layer and at least covers the second segment of the line 12 . In this way, the characteristic impedance of the first line 11 refers to the first reference layer 3, the characteristic impedance of the second line 12 refers to the second reference layer 5, and signal lines of different widths refer to different reference layers. , making the impedances of the first line 11 and the second line 12 continuous. At the same time, because the second reference layer 5 is a discrete copper foil layer, the cost is reduced.

As shown in FIG. 3 , in this embodiment, the radio frequency signal line further includes a first pad 13 and a second pad 14 arranged at both ends of the first section of the line 11, the first pad 13 and the second pad 14 The size of the second pad 14 in the direction parallel to the width of the first section of line 11 is greater than the width of the first section of line 11, the characteristic impedance of the first pad 13 and the second pad 13 The characteristic impedances of 14 are all referred to the second reference layer 5 . The first reference layer 3 is hollowed out at the position facing the first pad 13 and the second pad 14 . This embodiment can ensure that the signal line part and the bonding pad part of the high-speed signal line keep impedance continuity, and avoid signal reflection. It should be understood that the above-mentioned embodiment is only an example, and in fact, the pads and signal lines passed through during the complete transmission of the radio frequency signal can be set according to the above-mentioned rule, so as to ensure the impedance continuity of the entire line.

As another preferred embodiment of the present invention, please refer to FIG. 4, the first reference layer 3 is a continuous copper foil layer and covers the first signal layer 1, and the first reference layer 3 is facing the The position of the second section of the line 12 is hollowed out. The second reference layer 5 is a discrete copper foil layer and at least covers the second segment of the line 12 . Further, the printed circuit board also includes a second signal layer 6 located on the side of the second substrate 4 away from the first reference layer 3, and at least one signal line is arranged on the second signal layer 6, so The signal line does not overlap with the second reference layer. It can be understood that the signal lines on the second signal layer 6 may refer to the first reference layer 3 . In this way, the characteristic impedance of the first line 11 refers to the first reference layer 3, the characteristic impedance of the second line 12 refers to the second reference layer 5, and signal lines of different widths refer to different reference layers. , making the impedances of the first line 11 and the second line 12 continuous. At the same time, the space of the printed circuit board is more fully utilized, so that the structure of the printed circuit board is more compact and small.

As shown in FIG. 4, in this embodiment, the radio frequency signal line further includes a first pad 13 and a second pad 14 arranged at both ends of the first section of the line 11, the first pad 13 and the second pad 14 The size of the second pad 14 in the direction parallel to the width of the first section of line 11 is greater than the width of the first section of line 11, the characteristic impedance of the first pad 13 and the second pad 13 The characteristic impedances of 14 are all referred to the second reference layer 5 . The first reference layer 3 is hollowed out at the position facing the first pad 13 and the second pad 14 . This embodiment can ensure that the signal line part and the bonding pad part of the high-speed signal line keep impedance continuity, and avoid signal reflection. It should be understood that the above-mentioned embodiment is only an example, and in fact, the pads and signal lines passed through during the complete transmission of the radio frequency signal can be set according to the above-mentioned rule, so as to ensure the impedance continuity of the entire line.

As yet another preferred embodiment of the present invention, please refer to FIG. 5 , the printed circuit board further includes a third substrate 7 and a The third reference layer 8, the radio frequency signal line also includes a third section of the line 15, the third section of the line 15 is electrically connected to the end of the second section of the line 12 away from the first section of the line 11, the first section of the line 11 The width of the three-segment line 15 is greater than that of the second-segment line 12 , and the third-segment line 15 refers to the third reference layer 8 . The first reference layer 3 is a continuous copper foil layer and covers the first signal layer 1, and the first reference layer 3 is at a position facing the second line 12 and the third line 13 Hollow settings. The second reference layer 5 is a discrete copper foil layer and at least covers the second segment of the line 12 . The third reference layer 5 is a discrete copper foil layer and at least covers the third segment of the line 15 . In this way, the characteristic impedance of the first section of line 11 refers to the first reference layer 3, the characteristic impedance of the second section of line 12 refers to the second reference layer 5, and the characteristic impedance of the third section of line 15 Referring to the third reference layer 8 , signal lines of different widths refer to different reference layers, so that the impedances of the first line 11 and the second line 12 are continuous. At the same time, the layout of the radio frequency signal lines is more flexible, and the space of the printed circuit board is more fully utilized, so that the structure of the printed circuit board is more compact and small. It can be understood that, in this embodiment, the second reference layer 5 can also be a continuous copper foil layer and hollowed out at the position facing the third segment of the line 15, and the third reference layer 8 can also be It may be a continuous copper foil layer covering at least the third section of the line 15 . At the same time, the connection relationship and composition of parts with different line widths on the radio frequency signal line described in the present invention include but are not limited to the above-mentioned embodiments, as long as they can be used in other similar or Close specific forms that realize the solution of the present invention are all within the protection scope of the present invention.

As shown in FIG. 5, in this embodiment, the radio frequency signal line further includes a first pad 13 and a second pad 14 arranged at both ends of the first section of the line 11, the first pad 13 and the second pad 14 The size of the second pad 14 in the direction parallel to the width of the first section of line 11 is greater than the width of the first section of line 11, the characteristic impedance of the first pad 13 and the second pad 13 The characteristic impedances of 14 are all referred to the second reference layer 5 . The first reference layer 3 is hollowed out at the position facing the first pad 13 and the second pad 14 . This embodiment can ensure that the signal line part and the bonding pad part of the high-speed signal line keep impedance continuity, and avoid signal reflection. It should be understood that the above-mentioned embodiment is only an example, and in fact, the pads and signal lines passed through during the complete transmission of the radio frequency signal can be set according to the above-mentioned rule, so as to ensure the impedance continuity of the entire line. Of course, when the pads in the circuit have a larger width, the third reference layer 8 can also be referred to to obtain impedance continuity.

An embodiment of the present invention also provides a mobile terminal, including the above-mentioned printed circuit board. The mobile terminal refers to computer equipment that can be used on the move, including but not limited to mobile phones, notebooks, tablet computers, POS machines, vehicle-mounted computers, cameras, etc.

The above description is a preferred embodiment of the present invention, and it should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also considered Be the protection scope of the present invention.

Claims (10)

1. A printed circuit board, characterized in that it includes a stacked first signal layer, a first substrate, a first reference layer, a second substrate, and a second reference layer, and the first signal layer includes at least one radio frequency signal layer line, the radio frequency signal line includes a first section of line and a second section of line electrically connected, the width of the first section of line is smaller than the width of the second section of line, and the characteristic impedance of the first section of line refers to the first reference layer , the characteristic impedance of the second section of line refers to the second reference layer, and the characteristic impedance of the first section of line is equal to the characteristic impedance of the second section of line. 2. The printed circuit board according to claim 1, wherein the first signal layer comprises a first region and a second region, and the pad density on the first region is greater than that on the second region. Pad density, the first section of the radio frequency signal line is connected to the pad on the first area, and the second section of the radio frequency signal line is connected to the pad on the second area pad. 3. The printed circuit board according to claim 1, wherein the first reference layer is a continuous copper foil layer and covers the first signal layer, and the first reference layer is facing the first The position of the second section of the line is hollowed out. 4. The printed circuit board according to claim 3, wherein the second reference layer is a continuous copper foil layer covering the first signal layer. 5 . The printed circuit board according to claim 3 , wherein the second reference layer is a discrete copper foil layer and covers at least the second segment of the circuit. 6. The printed circuit board according to claim 5, wherein the printed circuit board further comprises a second signal layer located on the side of the second substrate away from the first reference layer, the second signal layer At least one signal line is arranged on the layer, and the signal line does not overlap with the second reference layer. 7. The printed circuit board according to claim 1, wherein the radio frequency signal line further comprises a third section of the line, and the third section of the line is electrically connected to the second section of the line away from the first section One end of the line, the width of the third line is equal to the width of the first line, and the third line refers to the first reference layer. 8. The printed circuit board according to claim 1, wherein the printed circuit board further comprises a third substrate and a third reference layer sequentially stacked on the side of the second reference layer away from the second substrate. Layer, the radio frequency signal line also includes a third section of the line, the third section of the line is connected to the end of the second section of the line away from the first section of the line, the width of the third section of the line is greater than the width of the first section of the line Two sections of line width, the third section of line refers to the third reference layer. 9. The printed circuit board according to claim 1, wherein the radio frequency signal line further comprises a first soldering pad and a second soldering pad arranged at both ends of the first segment of the line, and the first soldering pad and the dimension of the second pad in the direction parallel to the width of the first section of line is greater than the width of the first section of line, the characteristic impedance of the first pad and the characteristic impedance of the second pad Both refer to the second reference layer. 10. A mobile terminal, comprising the printed circuit board according to any one of claims 1-9.