CN113677089A

CN113677089A - Printed circuit board, antenna system and electronic equipment

Info

Publication number: CN113677089A
Application number: CN202110920472.9A
Authority: CN
Inventors: 陶士超; 黄明利
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-08-11
Filing date: 2021-08-11
Publication date: 2021-11-19
Anticipated expiration: 2041-08-11
Also published as: CN113677089B

Abstract

The embodiment of the application provides a printed circuit board, an antenna system and electronic equipment. This printed circuit board includes foam layer, bond line and conducting layer, and foam layer, bond line and conducting layer are range upon range of setting, and wherein: the value ranges of the loss tangent Df and the density rho of the foam layer are as follows: df is less than 0.003, rho is less than 0.6g/cm³(ii) a The foam layer can bear the following temperature T and pressure P: t is more than or equal to 130 ℃, and P is more than or equal to 0.1 Mpa; the thickness H1 of the bonding layer has the following value range: h1 is less than 0.15 mm. The printed circuit board of the embodiment of the application has the advantages that the loss tangent factor is small, the signal transmission loss is reduced, the transmission efficiency is improved, the density is low, the light weight is realized, meanwhile, the structure is simple, and the cost can be reduced.

Description

Printed circuit board, antenna system and electronic equipment

Technical Field

The present application relates to the field of electronic technology, and in particular, to a printed circuit board, an antenna system, and an electronic device.

Background

The printed circuit board in the antenna system requires the dielectric constant Dk and the loss tangent Df of the medium to be as small as possible, so that the aim of smaller signal transmission loss is fulfilled, the transmission efficiency can be improved, the station distribution density is finally realized to be small, and the ultimate benefit of social resources is saved. Moreover, the density of the current antenna plate or the whole machine level (injection molding process) is generally 2.0g/cm³In the above, the antenna PCB (printed circuit board) is based on board level and whole machine levelThe requirement for handleability requires weight reduction, i.e. a lower density of the components. In addition, the antenna PCB is required to have cost competitiveness based on the mass demand.

Based on the above several key competitive properties, the current antenna PCB or complete machine level solution cannot be satisfied at the same time for a while, and cannot perform continuous evolution iteration of the version.

Disclosure of Invention

The embodiment of the application provides a printed circuit board, antenna system and electronic equipment, printed circuit board's loss tangent factor is little, has reduced the signal transmission loss, has improved transmission efficiency to density is low, helps realizing the lightweight, and simple structure can reduce cost simultaneously.

Therefore, the embodiment of the application adopts the following technical scheme:

in a first aspect, an embodiment of the present application provides a printed circuit board, the printed circuit board includes a foam layer, an adhesive layer, and a conductive layer, the foam layer, the adhesive layer, and the conductive layer are stacked, wherein: the value ranges of the loss tangent Df and the density rho of the foam layer are as follows: df is less than 0.003, rho is less than 0.6g/cm³(ii) a The foam layer can bear the following temperature T and pressure P: t is more than or equal to 130 ℃, and P is more than or equal to 0.1 Mpa; the thickness H1 of the bonding layer has the following value range: h1 is less than 0.15 mm.

In above-mentioned scheme, the foam layer loss tangent is less, can reduce the transmission loss of signal, has improved transmission efficiency to, the component that printed circuit board includes is less, simple structure, and the density of foam layer is less simultaneously, helps reducing density, and further, the thickness of bond line is less, is favorable to realizing lightweight and reduce cost. In addition, the adhesive layer may also be selected from low loss tangent materials, for example, the adhesive layer has a loss tangent of less than 0.003 to further reduce the transmission loss of the signal. The conducting layer can be generally made of low-roughness copper foil, so that materials are convenient to obtain, and the cost is reduced.

In one possible implementation, the foam layer includes at least one of polyetherimide, polyetherketone, polyphenylene sulfide, polyphenylene oxide, phenolphthalein polyaryletherketone. The material has small loss tangent and low density, and can meet the use requirement. Of course, the foam layer may be made of other suitable materials according to different working requirements.

In one possible implementation, the bonding layer includes one of a low loss continuous fiber prepreg, a low loss chopped fiber prepreg, a reinforcement-free glue film, a low loss polyimide. The thickness of the material is small when in use, and the material can meet the use requirement. Of course, the adhesive layer may be selected from other suitable adhesives according to different working requirements, such as silicone double-sided adhesive tape, acrylic double-sided adhesive tape, and epoxy resin double-sided adhesive tape.

In one possible implementation, the conductive layer includes a first conductive layer disposed on a first side of the foam layer, and the adhesive layer includes a first adhesive layer disposed between the first conductive layer and the foam layer such that the first conductive layer is connected to the foam layer through the first adhesive layer. That is, when only one foam layer is included, a first adhesive layer and a first conductive layer may be disposed on a first side of the foam layer. When the printed circuit board is mounted to an antenna system, the first conductive layer may serve as an antenna pattern, and a chip of the antenna system may be electrically connected to the first conductive layer so as to transmit and/or receive a signal through the first conductive layer.

In one possible implementation, the conductive layer includes a second conductive layer disposed on a second side of the foam layer, and the adhesive layer includes a second adhesive layer disposed between the second conductive layer and the foam layer such that the second conductive layer is connected to the foam layer through the second adhesive layer. That is, when only one foam layer is included, a second adhesive layer and a second conductive layer may also be provided on the second side of the foam layer. Wherein the second side is opposite to the first side. The first adhesive layer and the second adhesive layer may be the same or different. The first conductive layer and the second conductive layer may be the same or different. When the printed circuit board is mounted to an antenna system, the first conductive layer and the second conductive layer may serve as an antenna pattern, and chips of the antenna system may be electrically connected to the first conductive layer and the second conductive layer, respectively, so as to transmit signals through the first conductive layer and the second conductive layer, respectively.

In one possible implementation, the foam layer includes a first foam layer and a second foam layer, the conductive layer includes a first conductive layer, a second conductive layer, and a third conductive layer, and the adhesive layer includes a first adhesive layer, a second adhesive layer, a third adhesive layer, and a fourth adhesive layer; the first conductive layer is disposed on a side of the first foam layer distal from the second foam layer, and the first adhesive layer is disposed between the first foam layer and the first conductive layer such that the first conductive layer is connected to the first foam layer by the first adhesive layer; the second adhesive layer, the second conductive layer, and the third adhesive layer are disposed in a stack between the first foam layer and the second foam layer; the third conductive layer is disposed on a side of the second foam layer distal from the first foam layer, and the fourth adhesive layer is disposed between the second foam layer and the third conductive layer such that the third conductive layer is connected to the second foam layer by the fourth adhesive layer. In this implementation, a first foam layer and a second foam layer are provided such that the printed circuit board may include a first conductive layer, a second conductive layer, and a third conductive layer. When the printed circuit board is mounted to the antenna system, the chip of the antenna system may be electrically connected to the first conductive layer, the second conductive layer, and the third conductive layer to transmit signals through the first conductive layer, the second conductive layer, and the third conductive layer, respectively. It will be appreciated that the printed circuit board may also include three or more foam layers and accordingly, more conductive layers and adhesive layers may be provided so that the printed circuit board may transmit signals through the more conductive layers.

In one possible implementation, the conductive layer is formed by a patterned metal foil that is disposed in a stack on the foam layer. That is, the conductive layer may be formed by first attaching a metal foil such as a copper foil to the foam layer through an adhesive layer and then patterning the metal foil on the foam layer.

In one possible implementation, the printed circuit board further includes a support layer disposed between the conductive layer and the adhesive layer. The supporting layer is arranged to support the conductive layer, so that the conductive layer is conveniently arranged on the foam layer.

In a possible implementation manner, the thickness H2 of the support layer has a value range of: h2 is less than 0.1 mm. In the implementation mode, the thickness range of the supporting layer can be limited, the strength of the supporting layer is enough, the conducting layer can be supported, the thickness of the supporting layer is not too large, and the light weight of the printed circuit board can be realized.

In one possible implementation, the conductive layer is formed by a patterned metal foil, which is arranged on top of the support layer, which is connected to the foam layer by the adhesive layer. That is, a metal foil may be first disposed on a support layer and patterned on the support layer to form a conductive layer, the conductive layer and the support layer may constitute a flexible circuit board FBC, and then the FPC may be attached to the foam layer through an adhesive layer.

In one possible implementation, the support layer comprises polyimide or polyethylene terephthalate. The material ensures that the strength of the supporting layer meets the supporting requirement, and the thickness of the supporting layer is not too large. It will be appreciated that other suitable materials may be selected for the support layer according to the actual working requirements.

In a second aspect, embodiments of the present application provide an antenna system, which includes a chip and the printed circuit board provided in the first aspect, wherein the conductive layer of the printed circuit board is used as an antenna pattern, and the chip is electrically connected to the conductive layer of the printed circuit board to transmit and/or receive signals through the conductive layer. Since the antenna system comprises the printed circuit board described above, all or at least part of the advantages of the printed circuit board described above are achieved.

In a third aspect, an embodiment of the present application provides an electronic device, which includes the antenna system provided in the second aspect.

Drawings

The drawings that accompany the detailed description can be briefly described as follows.

FIG. 1 is an exploded view of a printed circuit board;

fig. 2 is a schematic partial structural diagram of an antenna system according to an embodiment of the present disclosure;

fig. 3 is a partial schematic structural diagram of another antenna system according to an embodiment of the present application;

fig. 4 is an exploded schematic view of a printed circuit board according to a first embodiment of the present disclosure;

FIG. 5 is a schematic view of a pressing operation performed by a low pressure pressing apparatus;

FIG. 6 is a schematic view of a pressing operation performed by a high pressure pressing apparatus;

fig. 7 is a schematic view of an assembly structure of another printed circuit board according to the first embodiment of the present application;

fig. 8 is an exploded view of a printed circuit board according to a second embodiment of the present disclosure;

fig. 9 is a schematic view of an assembly structure of another printed circuit board according to a second embodiment of the present application.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to examples. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the present application and does not limit the scope of the present application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

The dielectric constant Dk and the loss tangent Df of the medium required by the antenna PCB are as small as possible, so that the purpose of smaller signal transmission loss is achieved, the transmission efficiency is improved, the station distribution density is finally low, and the ultimate benefit of social resources is saved. And, the present antennaThe density of the plate or the whole machine (injection molding process) is generally 2.0g/cm³Above, the antenna PCB needs to be light-weighted based on the requirements of board-level and complete-machine-level operability, i.e., the components are required to have lower density. In addition, the antenna PCB is required to have cost competitiveness based on the mass demand.

Fig. 1 is a schematic structural diagram of a printed circuit board. As shown in fig. 1, the printed circuit board has a low dielectric constant Dk of 1.2 to 1.7, and may include a conductive layer such as copper foil, an adhesive, a water-impermeable separator, a PSA adhesive, and a low dielectric constant material. Specifically, the materials of the printed circuit board may be arranged in the following order: conductive layer-adhesive-waterproofing membrane-PSA adhesive-low dielectric constant material-PSA adhesive-waterproofing membrane-adhesive (optional) -conductive layer (optional).

Roll-to-roll (roll-to-roll) lamination methods may be used during processing, for example, roll-to-roll is implemented for all components such as copper foil, adhesives, waterproofing membranes, PSA adhesives, low dielectric constant materials, etc., or other roll-to-roll-like alternatives may be used, for example, roll-to-roll is implemented only for copper foil, adhesives, waterproofing membranes, PSA adhesives, etc.

The printed circuit board does not solve the problem that the foam layer is not attacked by acid and alkali in the PCB manufacturing process, is flame-retardant and has extremely low loss, the related laminated components are too many, the dielectric constant and the loss tangent of the whole are greatly influenced, the extremely low level can not be achieved, for example, Dk is less than 1.15, Df is less than 0.001, the structure is complex, and the whole cost is still high. Therefore, the printed circuit board has a relatively large non-generalizability, i.e. does not have one or more of the above-described core competitive properties (e.g. low loss tangent, low density, low cost) of the antenna assembly (with a circuit pattern), so that the structure has not been applied in the printed circuit board field or as a batch of antenna assemblies (with a circuit pattern) from the popularization to the present.

In view of this, the present application provides a printed circuit board, an antenna system and an electronic device. The loss tangent factor of the printed circuit board is small, the signal transmission loss is reduced, the transmission efficiency is improved, the density is low, the light weight is facilitated, meanwhile, the structure is simple, and the cost can be reduced. The electronic device may include an antenna system to implement the function of transmitting and receiving signals. The antenna system may include a chip and a printed circuit board, and the patterned conductive layer in the printed circuit board may serve as an antenna pattern, and the chip is electrically connected to the conductive layer of the printed circuit board to enable transmission and/or reception of signals through the conductive layer.

Fig. 2 is a schematic partial structural diagram of an antenna system according to an embodiment of the present application. As shown in fig. 2, the antenna system includes a printed circuit board 10 as an antenna guide sheet, a board body 20 (a chip may be disposed in the board body) under the printed circuit board 10, a heat sink 30, a fastener 40, a filter 50, a resistor 60, a capacitor 70, and the like, the printed circuit board 10 may include a patterned conductive layer as an antenna pattern, and the board body 20 may be mounted on the heat sink 30 by the fastener 40 such as a screw. The heat sink 30 is typically a metallic structure. In fig. 2, a plurality of printed circuit boards 10 may be disposed on a board body 20, and the respective components of the antenna system cooperate with each other to perform a function of transmitting and receiving signals.

Fig. 3 is a partial schematic structural diagram of another antenna system according to an embodiment of the present application. As shown in fig. 3, the antenna system includes a printed circuit board 10 ' as an air feed antenna, a board body 20 ' (a chip may be disposed inside the board body) under the printed circuit board 10 ', a heat sink 30 ', a fastener 40 ', a filter 50 ', a resistor 60 ', a capacitor 70 ', and the like, the printed circuit board 10 ' may include a patterned conductive layer as an antenna pattern, and the printed circuit board 10 ' and the board body 20 ' may be mounted on the heat sink 30 ' by a fastener 40 ', such as a screw. The heat sink 30' is typically a metallic structure. The components of the antenna system can be matched with each other to realize the function of transmitting and receiving signals.

The foam layer may be bonded to a copper foil or a flexible printed circuit board FPC through an adhesive layer to form the printed circuit board 10, 10', the FPC including a patterned copper foil, i.e., a conductive layer and a support layer, such as Polyimide (PI) or polyethylene terephthalate (PET). The printed circuit board has the properties of low dielectric constant, low loss tangent and light weight, can meet the requirement of the current antenna assembly based on different matrix resin materials and foaming process types, can be popularized and applied, and is suitable for all PCB or other board-level applications needing ultra-low dielectric constant Dk/loss tangent Df materials. The specific structure of the printed circuit board will be described with reference to the accompanying drawings.

Fig. 4 is an exploded schematic view of a printed circuit board according to a first embodiment of the present disclosure. As shown in fig. 4, the printed circuit board includes a foam layer 1, an adhesive layer 2, and a conductive layer 3. The foam layer 1, the adhesive layer 2 and the conductive layer 3 are in a stacked arrangement. Wherein, the value range of the loss tangent Df of the foam layer 1 is as follows: df is less than 0.003; the density ρ of the foam layer 1 has a value range of: rho is less than 0.6g/cm³(ii) a The value range of the temperature T which can be borne by the foam layer 1 is as follows: t is more than or equal to 130 ℃; the value range of the pressure P which can be borne by the foam layer 1 is as follows: p is more than or equal to 0.1 Mpa. The thickness H1 of the adhesive layer 2 has a value range of: h1 is less than 0.15 mm. The printed circuit board has extremely low loss, can reduce signal transmission loss and improve transmission efficiency, has a simple structure and low density, is easy to realize light weight and reduce cost, and is suitable for lower antenna PCB development and continuous evolution iteration of versions.

Wherein, the foam layer 1 may include at least one of polyetherimide, polyether ketone, polyphenylene sulfide, polyphenylene oxide, phenolphthalein polyaryletherketone. The material has small loss tangent and low density, and can meet the use requirement. Of course, the foam layer may be made of other suitable materials according to different working requirements. In addition, the thickness of the foam layer 1 can be selected according to the actual working requirements, for example, 0.5mm to 30 mm.

Further, the adhesive layer 2 may also be a low-loss adhesive layer. For example, the loss tangent of the adhesive layer 2 may be less than 0.003 in order to further reduce the signal transmission loss and improve the transmission efficiency. The adhesive layer 2 may include one of a low-loss continuous fiber prepreg, a low-loss chopped fiber prepreg, a reinforcement-free glue film, and a low-loss polyimide. The thickness of the material is small when in use, and the material can meet the use requirement. Of course, the adhesive layer 2 may be selected from other suitable adhesives according to different working requirements, such as silicone double-sided adhesive tape, acrylic double-sided adhesive tape, and epoxy resin double-sided adhesive tape. Additionally, in one example, the thickness H1 of the adhesive layer 2 may be less than 0.1 mm.

The conductive layer 3 may have a thickness of 50um or less, and may be made of copper, aluminum, or the like, for example, a low roughness copper foil in one example. The thickness of the conductive layer 3 may range from 7um to 35 um. The conductive layer 3 may be formed by patterning a metal foil, such as a copper foil, which is layered on the foam layer 1. That is, a metal foil may be first attached to the foam layer 1 through the adhesive layer 2, and then the metal foil may be patterned to form the conductive layer 3.

It should be noted that if the selection of the bonding layer is not suitable, for example, a common prepreg (PP, polypropylene) is used to bond the copper foil and the foam layer to form the printed circuit board, and the specific structure may be, for example, copper foil-common continuous glass fiber prepreg-foam layer-common continuous glass fiber prepreg-copper foil. The dielectric constant and the loss tangent factor of the common PP are higher, so that the overall dielectric constant and the loss tangent are higher, and the embodiment is more obvious particularly when the thickness is thicker. At this time, if the processing mode is not selected properly, for example, the traditional PCB lamination process is adopted to laminate the ultra-high hardness/high temperature resistant foam layer, the common continuous glass fiber prepreg and the copper foil, and because of the ultra-high hardness/high temperature resistant foam layer, a mature product can bear the temperature and pressure of the traditional lamination process temporarily, and can collapse after lamination, and the ultra-high hardness/high temperature resistant foam layer does not have the characteristics of low dielectric constant and low loss tangent factor; in addition, the thickness variation is large and cannot meet the thickness requirement of the finished assembly.

As shown in fig. 4, the specific configuration of the printed circuit board according to the first embodiment of the present application may have the following three schemes:

first alternative-the conductive layer 3 may comprise a first conductive layer 31 disposed on a first side of the foam layer 1, the adhesive layer 2 comprises a first adhesive layer 21, and the first adhesive layer 21 is disposed between the first conductive layer 31 and the foam layer 1 such that the first conductive layer 31 is connected to the foam layer 1 by the first adhesive layer 21.

Second alternative-the conductive layer 3 may include a second conductive layer 32 disposed on a second side of the foam layer 1, the adhesive layer 2 includes a second adhesive layer 22, and the second adhesive layer 22 is disposed between the second conductive layer 32 and the foam layer 1 such that the second conductive layer 32 is connected to the foam layer 1 through the second adhesive layer 22.

Third approach-the conductive layer 3 may include a first conductive layer 31 disposed on a first side of the foam layer 1, the adhesive layer 2 includes a first adhesive layer 21, and the first adhesive layer 21 is disposed between the first conductive layer 31 and the foam layer 1 such that the first conductive layer 31 is connected to the foam layer 1 by the first adhesive layer 21. The conductive layer 3 comprises a second conductive layer 32 arranged on the second side of the foam layer 1, the adhesive layer 2 comprises a second adhesive layer 22, and the second adhesive layer 22 is arranged between the second conductive layer 32 and the foam layer 1, so that the second conductive layer 32 is connected to the foam layer 1 via the second adhesive layer 22. The first side surface and the second side surface are oppositely arranged, and the first adhesive layer 21 and the second adhesive layer 22 may be the same or different, and may be specifically selected according to the working requirement.

Also, the method of manufacturing the printed circuit board shown in fig. 4 may include the steps of:

1) an adhesive layer 2 is provided on the foam layer 1, and the adhesive layer 2 may include a first adhesive layer 21 and/or a second adhesive layer 22.

When the bonding layer 2 is glue, the glue can be coated on the foam layer 1; when the adhesive layer 2 is a double-sided tape, it may be stuck on the foam layer 1. In addition, when it is necessary to provide the first conductive layer 31, a first adhesive layer 21 may be provided on the foam layer 1 to adhere the first conductive layer 31; when it is desired to provide the second conductive layer 32, a second adhesive layer 22 may be provided on the foam layer 1 to adhere the second conductive layer 32.

2) A metal foil is laid on the side of the foam layer 1 provided with the adhesive layer 2 and is pressed by means of a pressing device.

The metal foil may be patterned to form the conductive layer 3, i.e. the first conductive layer 31 and/or the second conductive layer 32. Moreover, the pressure applied to the foam layer 1 by the laminating equipment is matched with the pressure which can be borne by the foam layer 1, and the temperature of the laminating equipment is matched with the temperature which can be borne by the adhesive layer 2. The pressing operation will be described below with reference to fig. 5 and 6.

Fig. 5 is a schematic view of the pressing operation performed by the low-pressure pressing apparatus. As shown in fig. 5, when the working pressure of the laminating apparatus satisfies the pressure required for the laminating operation, the laminating apparatus only contacts the printed circuit board when performing the laminating operation. At this time, the pressing device is a low-pressure pressing device, and the size of the steel plate or other smooth surface hard plates and aluminum sheets of the low-pressure pressing device can be similar to or slightly larger than that of the low-loss tangent material, namely the foam layer 1. Besides, the aluminum sheet and the release film can also be selected from other auxiliary materials with buffer function which are combined into a whole or a plurality of materials.

Because the pressure required for pressing and pasting the printed circuit board is smaller, the pressure required by pressing and pasting operation can be met when low-pressure pressing equipment is adopted. In one example, the maximum working pressure of the low-pressure pressing device may be lower than 0.3Mpa, and the pressure P1 for the pressing operation of the low-pressure pressing device is in the following range: p1 is less than 0.28Mpa, the value range of the temperature T1 for the pressing operation of the low-pressure pressing equipment is as follows: t1 < 200 ℃. In particular, the pressure P1 may be 0.1MPa and the temperature T1 may be 180 ℃.

That is, the lamination can be performed by using a device capable of supporting low-pressure uniform lamination, and the lamination parameters are matched with the performances of the foam layer 1 and the adhesive layer 2.

Fig. 6 is a schematic view of the pressing operation performed by the high-pressure pressing apparatus. As shown in fig. 6, when the working pressure of the laminating device is higher than the pressure required by the laminating operation, the printed circuit board is placed in the height-limiting supporting member, and the printed circuit board is higher than the height-limiting supporting member, and the laminating device simultaneously contacts the printed circuit board and the height-limiting supporting member when the laminating operation is performed, so that the height-limiting supporting member shares part of the pressure, and the pressure borne by the printed circuit board is ensured to meet the pressure required by the laminating operation. That is, the pressing device is a high-pressure pressing device, and the size of the steel plate or other smooth and hard plates and aluminum sheets of the high-pressure pressing device can be larger than that of the low-loss tangent material, namely the foam layer 1, so that the height-limiting supporting piece can be pressed at the same time. Besides, the aluminum sheet and the release film can also be selected from other auxiliary materials with buffer function which are combined into a whole or a plurality of materials.

When the high-pressure laminating equipment is adopted, the working pressure of the high-pressure laminating equipment is higher than that required by the pressing operation. In one example, the minimum working pressure of the high-pressure laminating device may be higher than 1.2Mpa, the printed circuit board may be placed in the height-limiting support, and 5% to 10% of the thickness of the printed circuit board may be higher than the height-limiting support, the laminating parameters of the high-pressure laminating device may be matched with the performance of the height-limiting support, the laminating device may contact the printed circuit board and the height-limiting support simultaneously when performing laminating operation, the pressure of the laminating device may be, for example, 1.35Mpa when performing laminating operation, and the value range of the pressure P2 on the printed circuit board may be: p2 is less than 0.7Mpa, the rest pressure can be borne by the height-limiting supporting piece, and the value range of the temperature T2 for the pressing operation of the pressing equipment can be T2 less than 210 ℃. Specifically, the pressure P2 may be 0.3MPa and the temperature T2 may be 200 ℃.

That is to say, the traditional pressing equipment can be adopted to complete pressing, and the pressure of the traditional pressing equipment is generally higher, so that the traditional pressing equipment can be matched with the height-limiting supporting piece to share the pressure, and pressing parameters matched with the performances of the foam layer 1 and the bonding layer 2 are realized.

3) And a photosensitive material is attached to the metal foil, and the metal foil is exposed, developed, and etched to form the conductive layer 3.

It should be noted that the above steps are only a few main steps, and the method for manufacturing the printed circuit board may further include other steps, such as drilling before performing step 3), and performing solder mask, molding after performing step 3).

The printed circuit board of the first embodiment of the present invention has a low loss tangent Df, Df < 0.003, typically Df < 0.001; has lower density rho, generally rho is less than 0.6g/cm³Typical values of rho < 0.2g/cm³(ii) a Has lower cost.

Fig. 7 is a schematic view of an assembly structure of another printed circuit board according to the first embodiment of the present application. As shown in fig. 7, the foam layer includes a first foam layer 11 and a second foam layer 12, the conductive layer 3 includes a first conductive layer 31, a second conductive layer 32, and a third conductive layer 33, and the adhesive layer 2 includes a first adhesive layer 21, a second adhesive layer 22, a third adhesive layer 23, and a fourth adhesive layer 24. The first conductive layer 31 is arranged on the side of the first foam layer 11 remote from the second foam layer 12, and the first adhesive layer 21 is arranged between the first foam layer 11 and the first conductive layer 31, so that the first conductive layer 31 is connected to the first foam layer 11 by the first adhesive layer 21. Second adhesive layer 22, second conductive layer 32, and third adhesive layer 23 are disposed in a stack between first foam layer 11 and second foam layer 12. The third electrically conductive layer 33 is arranged on the side of the second foam layer 12 remote from the first foam layer 11, and the fourth adhesive layer 24 is arranged between the second foam layer 12 and the third electrically conductive layer 33, so that the third electrically conductive layer 33 is connected to the second foam layer 12 by means of the fourth adhesive layer 24.

The materials of the first adhesive layer 21, the second adhesive layer 22, the third adhesive layer 23 and the fourth adhesive layer 24 may be the same or different, and may be specifically selected according to the working requirement. When the printed circuit board is mounted to the antenna system, the chip of the antenna system may be electrically connected to the first conductive layer 31, the second conductive layer 32, and the third conductive layer 33 so as to transmit signals through the first conductive layer 31, the second conductive layer 32, and the third conductive layer 33, respectively.

It is understood that the printed circuit board may further include a plurality of foam layers 1, in which case, a conductive layer 3 is disposed between two adjacent foam layers 1, both sides of the conductive layer 3 are respectively connected to two adjacent foam layers 1 through adhesive layers 2, and an outer side surface of at least one of the two foam layers 1 located at the outer side may be provided with the conductive layer 3.

The method of manufacturing the printed circuit board shown in fig. 7 may include the steps of:

1) and manufacturing a first laminated structure D1. As shown in fig. 7, the first laminate structure may include a first foam layer 11, a first adhesive layer 21 and a first conductive layer 31 disposed on a first side of the first foam layer 11, and a second adhesive layer 22 and a second conductive layer 32 disposed on a second side of the first foam layer 11.

2) And a second stacked structure D2 is produced. As shown in fig. 7, the second laminate structure includes a second foam layer 12, a third adhesive layer 23 disposed on a first side of the second foam layer 12, and a fourth adhesive layer 24 and a third conductive layer 33 disposed on a second side of the second foam layer 12.

3) The second conductive layer 32 is patterned, and the first conductive layer 31, the second conductive layer 32, and the third conductive layer 33 are browned.

4) And pressing the first laminated structure D1 and the second laminated structure D2 to form an integral structure, wherein the second conductive layer 32 is in contact connection with the third adhesive layer 23.

5) The whole is drilled and the first conductive layer 31 and the third conductive layer 33 are patterned. At this time, the patterning of the outer

conductive layers

31 and 33 is completed on the entire structure formed by the first and second stacked structures D1 and D2.

It should be noted that the above steps are only a few main steps, and the method for manufacturing the printed circuit board may further include other steps, such as performing step 5), followed by performing solder resist, molding, and the like. In addition, steps 1) to 5) are only one possible specific example, and some of the processes in the above steps may be modified, for example, after performing steps 1) to 2), the first conductive layer 31, the second conductive layer 32, and the third conductive layer 33 may be patterned together, and the browning treatment may not be performed, followed by step 4), and then the whole formed in step 4) may be drilled. At this time, patterning of the first conductive layer 31 and the third conductive layer 33 may be completed on the first laminate structure D1 and the second laminate structure D2, respectively.

Fig. 8 is an exploded schematic view of a printed circuit board according to a second embodiment of the present disclosure. As shown in fig. 8, the printed circuit board of the second embodiment of the present application is different from the printed circuit board of the first embodiment in that the printed circuit board may further include a support layer 4, and the support layer 4 is disposed between the conductive layer 3 and the adhesive layer 2. The thickness H2 of the support layer 4 has a value in the range: h2 is less than 0.1 mm. The conductive layer 3 and the support layer 4 constitute a flexible circuit board FPC. Also, the conductive layer 3 may be formed by patterning a metal foil, which is layered on the support layer 4, and the support layer 4 is connected to the foam layer 1 through the adhesive layer 2. That is, a metal foil such as copper foil may be first attached to the support layer 4, then an FPC may be formed on the patterned metal foil, and then the FPC may be attached to the foam layer 1.

The support layer 4 is a low loss tangent material, and may include Polyimide (PI) or polyethylene terephthalate (PET). In one example, the support layer in the FPC is PI, and the thickness may be less than or equal to 25 um.

The printed circuit board of the second embodiment of the present application has a low loss tangent factor, Df < 0.003, typically Df < 0.001; has lower density, generally less than 0.6g/cm³Typical values < 0.2g/cm³(ii) a Has lower cost.

The method of manufacturing the printed circuit board shown in fig. 8 may include the steps of:

1) and laying a metal foil on the supporting layer 4, and patterning the metal foil on the supporting layer 4 to form the Flexible Printed Circuit (FPC), wherein the patterned metal foil is the conductive layer 3. I.e. the FPC may comprise a support layer 4 and a conductive layer 3.

Wherein the FPC may include the FPC1 and/or the FPC2, the conductive layer 3 may include the first conductive layer 31 and/or the second conductive layer 32, and correspondingly, the support layer 4 may include the first support layer 41 and/or the second support layer 42, the first conductive layer 31 and the first support layer 41 forming the FPC1, and the second conductive layer 32 and the second support layer 42 forming the FPC 2.

2) An adhesive layer 2 is provided on one of the foam layer 1 and the support layer 4.

That is, the adhesive layer 2 may be provided on the foam layer 1 so as to adhere the support layer 4; alternatively, an adhesive layer 2 may be provided on the support layer 4 in order to adhere the foam layer 1. Wherein the adhesive layer 2 may include a first adhesive layer 21 and/or a second adhesive layer 22. Specifically, when the FPC1 needs to be provided, the adhesive layer 2 may include a first adhesive layer 21 for attaching the first support layer 41 in the FPC 1; when the FPC2 is required to be provided, the adhesive layer 2 may include a second adhesive layer 22 for affixing the second support layer 42 in the FPC 2; when it is necessary to provide

FPCs

1 and 2, the adhesive layer 2 includes a first adhesive layer 21 and a second adhesive layer 22.

3) FPC1 and/or FPC2 are laid on foam layer 1 in the order that adhesive layer 2 is located between support layer 4 and foam layer 1, and a laminating operation is performed by a laminating apparatus. The specific process of the pressing operation performed by the pressing device can refer to the first embodiment.

Alternatively, step 3) may be replaced by step 4) of attaching the support layer 4 and the foam layer 1 via the adhesive layer 2 and pressing them via a roller. That is, with respect to the printed circuit board including the support layer 4 of the second embodiment, the following method may also be employed: firstly, adhering a double-sided adhesive tape to at least one of the foam layer 1 and the support layer 4, wherein the conductive layer 3 is adhered to the support layer 4, then, the foam layer 1 and the support layer 4 are connected through the double-sided adhesive tape, and then, rolling is carried out through a roller to form the printed circuit board.

It should be noted that the above steps are only a few main steps, and the manufacturing method of the printed circuit board may further include other steps, such as drilling, soldering, forming, etc. after step 3) or step 4).

Fig. 9 is a schematic view of an assembly structure of another printed circuit board according to a second embodiment of the present application. As shown in fig. 9, the foam layer 1 includes a first foam layer 11 and a second foam layer 12, an FPC2 is disposed between the two foam layers 1, an FPC2 includes a second support layer 42 and a second conductive layer 32, a second adhesive layer 22 is disposed between the second support layer 42 and the first foam layer 11, a third adhesive layer 23 is disposed between the second conductive layer 32 and the second foam layer 12, a first adhesive layer 21 and an FPC1 are disposed on a side of the first foam layer 11 away from the second foam layer 12, an FPC1 includes a first support layer 41 and a first conductive layer 31, a fourth adhesive layer 24 and an FPC3 are disposed on a side of the second foam layer 12 away from the first foam layer 11, and an FPC3 includes a third support layer 43 and a third conductive layer 33. In fig. 9, both

FPCs

1 and 3 are provided, and alternatively, only one of

FPCs

1 and 3 may be provided.

The method of manufacturing the printed circuit board shown in fig. 9 may include the steps of:

1) and manufacturing a flexible circuit board FPC, wherein the FPC comprises at least one of a first flexible circuit board FPC1 and a third flexible circuit board FPC3 and a second flexible circuit board FPC 2.

Specifically, a metal foil such as copper foil may be first attached to the support layer 4, and then the conductive layer 3 is formed on the patterned metal foil, thereby completing the FPC production. The patterned conductive layer 3 may serve as an antenna pattern.

2) And manufacturing a first laminated structure D1. As shown in fig. 9, the first laminate structure D1 may include a first foam layer 11, a first adhesive layer 21 and an FPC1 provided to a first side of the first foam layer 11, and a second adhesive layer 22 and an FPC2 provided to a second side of the first foam layer 11.

3) And a second stacked structure D2 is produced. As shown in fig. 9, the second laminate structure D2 includes a second foam layer 12, a third adhesive layer 23 provided on a first side of the second foam layer 12, and a fourth adhesive layer 24 and FPC3 provided on a second side of the second foam layer 12.

4) The first stacked structure D1 and the second stacked structure D2 were pressed to form an integral structure in which the second conductive layer 32 was in contact with the third adhesive layer 23.

5) The whole is drilled and the first conductive layer 31 and the third conductive layer 33 are patterned.

It should be noted that the above steps are only a few main steps, and the method for manufacturing the printed circuit board may further include other steps, such as performing step 5), followed by performing solder resist, molding, and the like.

In summary, the embodiments of the present application provide a printed circuit board with very low loss. The following improvements are mainly made:

first, the structure of the printed circuit board is simplified. Specifically, the printed circuit board may include a foam layer 1, an adhesive layer 2, and a conductive layer 3. The number of the conductive layer 3 and the adhesive layer 2 may be set according to actual working requirements, for example, the conductive layer 3 is respectively disposed on two sides or one side of the foam layer 1, and the foam layer 1 may also be provided with multiple layers. In addition, a support layer 4 may be disposed between the conductive layer 3 and the adhesive layer 2.

Secondly, parameters of at least some of the components in the printed circuit board are optimized. Specifically, the foam layer 1 may comprise one of polyetherimide, polyether ketone, polyphenylene sulfide, polyphenylene oxide, phenolphthalein polyaryletherketone, etc., the loss tangent Df may be less than 0.003, high temperature compression resistance (greater than or equal to 0.1Mpa @130 ℃), and low density (< 0.6 g/cm)³). The adhesive layer 2 may include one of a low-loss continuous fiber prepreg, a low-loss chopped fiber prepreg, a reinforcement-free glue film, a low-loss polyimide, etc., the low loss may be less than 0.003, and the thickness may be less than 0.15 mm.

Therefore, the printed circuit board is simple in structure, low in processing complexity and low in cost, the foam layer 1 has a low loss tangent factor, the adhesive layer 2 has the characteristic of low thickness, and the loss tangent factor of the whole assembly is reduced, so that the loss tangent factor of the printed circuit board is small, the density is low, and the light weight is facilitated.

Further, in the processing process, the pressing parameters of the pressing equipment are matched with the performances of the foam layer 1, the bonding layer 2, the supporting layer 4 and the like, so that no collapse is ensured, and the peeling strength is sufficient. Specifically, the following two pressing processes can be adopted:

1) the conductive layer 3 such as copper foil or FPC is bonded with the foam layer by using a low-pressure pressing process, a pressing device capable of realizing low pressure is needed, and pressing parameters of the pressing device during pressing operation can be 0.1MPa and 180 ℃.

2) The traditional pressing process is adopted to realize the adhesion of the conductive layer such as copper foil or FPC and the foam layer, a height-limiting support piece is needed to avoid the pressing collapse, and the pressing parameters of the pressing equipment during the pressing operation can be 1.35Mpa and 200 ℃. At the moment, the pressure can be borne by the printed circuit board and the height-limiting supporting piece together, and the pressure shared on the printed circuit board is ensured not to exceed the pressure required by pressing.

Finally, the description is as follows: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A printed circuit board comprising a foam layer, an adhesive layer and a conductive layer, the foam layer, the adhesive layer and the conductive layer being in a stacked arrangement, wherein:

the value ranges of the loss tangent Df and the density rho of the foam layer are as follows: df is less than 0.003, rho is less than 0.6g/cm³(ii) a The above-mentionedThe foam layer can bear the following temperature T and pressure P: t is more than or equal to 130 ℃, and P is more than or equal to 0.1 Mpa;

the thickness H1 of the bonding layer has the following value range: h1 is less than 0.15 mm.

2. The printed circuit board of claim 1, wherein the foam layer comprises at least one of polyetherimide, polyetherketone, polyphenylene sulfide, polyphenylene ether, phenolphthalein polyaryletherketone.

3. The printed circuit board of claim 1 or 2, wherein the bonding layer comprises one of a low loss continuous fiber prepreg, a low loss chopped fiber prepreg, a reinforcement-free glue film, a low loss polyimide.

4. The printed circuit board of any of claims 1-3, wherein the conductive layer comprises a first conductive layer disposed on a first side of the foam layer, and the adhesive layer comprises a first adhesive layer disposed between the first conductive layer and the foam layer such that the first conductive layer is connected to the foam layer by the first adhesive layer.

5. The printed circuit board of any of claims 1-4, wherein the conductive layer comprises a second conductive layer disposed on a second side of the foam layer, and wherein the adhesive layer comprises a second adhesive layer disposed between the second conductive layer and the foam layer such that the second conductive layer is connected to the foam layer through the second adhesive layer.

6. The printed circuit board of any of claims 1-3, wherein the foam layer comprises a first foam layer and a second foam layer, the conductive layer comprises a first conductive layer, a second conductive layer, and a third conductive layer, and the adhesive layer comprises a first adhesive layer, a second adhesive layer, a third adhesive layer, and a fourth adhesive layer;

the first conductive layer is disposed on a side of the first foam layer distal from the second foam layer, and the first adhesive layer is disposed between the first foam layer and the first conductive layer such that the first conductive layer is connected to the first foam layer by the first adhesive layer;

the second adhesive layer, the second conductive layer, and the third adhesive layer are disposed in a stack between the first foam layer and the second foam layer;

the third conductive layer is disposed on a side of the second foam layer distal from the first foam layer, and the fourth adhesive layer is disposed between the second foam layer and the third conductive layer such that the third conductive layer is connected to the second foam layer by the fourth adhesive layer.

7. A printed circuit board according to any of claims 1-6, characterized in that the electrically conductive layer is formed by a patterned metal foil, which is arranged on top of the foam layer.

8. The printed circuit board of any of claims 1-6, further comprising a support layer disposed between the conductive layer and the adhesive layer.

9. The printed circuit board of claim 8, wherein the thickness H2 of the support layer has a value in the range of: h2 is less than 0.1 mm.

10. A printed circuit board according to claim 8 or 9, characterized in that the conductive layer is formed by a patterned metal foil, which is arranged on top of the support layer, which is connected to the foam layer by means of the adhesive layer.

11. A printed circuit board according to any of claims 8-10, wherein the support layer comprises polyimide or polyethylene terephthalate.

12. An antenna system comprising a chip and a printed circuit board according to any one of claims 1-11, the conductive layer of the printed circuit board serving as an antenna pattern, the chip being electrically connected to the conductive layer of the printed circuit board for transmitting and/or receiving signals through the conductive layer.

13. An electronic device, characterized in that it comprises an antenna system according to claim 12.