阅读说明：本技术 一种超低损耗及高散热的高频印制电路板的制作方法 (Manufacturing method of high-frequency printed circuit board with ultralow loss and high heat dissipation ) 是由 戴银海 陈彦青 管美章 朱忠翰 江菊芳 牛顺义 邓健 吴胜 陶翠云 于 2021-08-30 设计创作，主要内容包括：本发明公开了一种超低损耗及高散热的高频印制电路板的制作方法,该方法是将紫铜板与微波介质覆铜板压合为多层板,并在紫铜板内部开设空槽后,在开设空槽一面再与微波介质基板压合形成空气腔状多层高频印制电路板,该方案与传统的PCB加工工艺对比能够显著增加PCB散热的同时降低高频信号的损耗,实现高频微波信号的稳定传输。(The invention discloses a manufacturing method of a high-frequency printed circuit board with ultralow loss and high heat dissipation, which comprises the steps of laminating a red copper plate and a microwave medium copper-clad plate into a multilayer plate, forming an empty groove in the red copper plate, and laminating the empty groove on one surface of the red copper plate and a microwave medium substrate to form an air cavity-shaped multilayer high-frequency printed circuit board.)

1. A manufacturing method of a high-frequency printed circuit board with ultra-low loss and high heat dissipation is characterized by comprising the following steps:

the method comprises the following steps: sequentially laminating an upper high-frequency microwave core board (4), an RT6002 board (6), a prepreg (7), a copper plate I (1), a conductive adhesive layer (3), a copper plate II (2) and a lower high-frequency microwave core board (5) to form a PCB;

step two: a cavity (12) is formed in the PCB obtained in the step one, and the conductive adhesive layer (3) and the red copper plate (1) on the upper layer of the conductive adhesive layer are arranged in the cavity (12);

step three: step blind grooves (8) are formed in the PCB obtained in the step one;

step four: and C, manufacturing a coaxial radio frequency transmission hole (9), a through hole (11) and a blind hole (10) in the PCB obtained in the step I.

2. The manufacturing method of the ultra-low loss and high heat dissipation high-frequency printed circuit board according to claim 1, characterized in that the upper layer high-frequency microwave core board (4) is an RT5880 multi-layer board, and the RT5880 multi-layer board is formed by pressing three RT5880 board layers;

the lower-layer high-frequency microwave core plate (5) is an RT6002 multilayer plate, and the RT6002 multilayer plate is formed by laminating two RT6002 plates (6).

3. The manufacturing method of the high-frequency printed circuit board with ultra-low loss and high heat dissipation according to claim 1, wherein the cavity (12) is a closed cavity after vacuum lamination, and the depth of the cavity (12) is the sum of the thickness of the copper plate I (1) and the thickness of the conductive adhesive layer (3).

4. The manufacturing method of the high-frequency printed circuit board with ultra-low loss and high heat dissipation according to claim 1, wherein the stepped blind groove (8) is formed from the top of the PCB to the bottom, and the bottom of the stepped blind groove (8) is located on the upper surface of the first copper plate (1).

5. The method for manufacturing a high-frequency printed circuit board with ultra-low loss and high heat dissipation according to claim 1, wherein the coaxial radio frequency transmission holes (9) comprise a radio frequency signal transmission hole of a microstrip line layer above the first copper plate (1) and a microstrip line layer below the second copper plate (2), the radio frequency signal transmission hole is located in the middle of a signal shielding hole formed by the first copper plate (1) and the second copper plate (2), and the signal shielding hole is coaxial with the radio frequency signal transmission hole.

6. The manufacturing method of the high-frequency printed circuit board with the ultra-low loss and the high heat dissipation according to claim 3 or 4, characterized in that the prepreg (7) or the conductive adhesive layer (3) used in the intermediate layer of the stepped blind slot (8) and the cavity (12) are subjected to windowing treatment.

7. The manufacturing method of high-frequency printed circuit board with ultra-low loss and high heat dissipation according to claim 1, wherein the through hole (11) is a hole for connecting a copper foil circuit layer from the top to the bottom of the PCB.

8. The manufacturing method of the high-frequency printed circuit board with ultra-low loss and high heat dissipation according to claim 1, wherein the blind holes (10) are holes for connecting the top or bottom of the PCB to the middle copper foil circuit layer of the PCB.

Technical Field

The invention relates to the technical field of printed circuit board manufacturing, in particular to a manufacturing method of a high-frequency printed circuit board with ultralow loss and high heat dissipation.

Background

Due to the fact that the multifunctional printed circuit board is applied more and more, in the field of microwave printed circuit board manufacturing, the designed signal frequency is higher and higher, and PCBs designed in double high-frequency bands are more and more. In order to realize high-frequency signal transmission, designers prefer boards and prepregs with lower dielectric constant values when selecting microwave dielectric substrates, but the currently manufactured microwave board Dk with the lowest dielectric constant is 2.0, and in order to further reduce the dielectric constant value between high-frequency signals, the design of a vacuum cavity (Dk is 1.0) can effectively solve the above problems.

Along with microwave circuit board integrated level is higher and higher, the heat dissipation problem also becomes the problem that the user is key to pay attention to, and along with the research and development of copper imbed pressfitting technique, utilize the large tracts of land copper of laying to carry out the connection of stratum heat conduction, can effectual promotion radiating efficiency.

In addition, in order to improve the signal transmission quality and enhance the anti-interference capability of signal transmission, a circle of signal shielding holes are generally processed around the signal transmission holes, so that the anti-interference and shielding functions of signals are realized.

The invention aims to integrate the design of a vacuum cavity, heat dissipation and a coaxial hole, realize the processing of a dual-band high-frequency PCB and obtain a manufacturing method of a high-frequency printed circuit board with ultralow loss and high heat dissipation.

Disclosure of Invention

The invention aims to provide a manufacturing method of a high-frequency printed circuit board with ultralow loss and high heat dissipation so as to solve the problems in the background technology.

The purpose of the invention can be realized by the following technical scheme:

a manufacturing method of a high-frequency printed circuit board with ultra-low loss and high heat dissipation comprises the following steps:

the method comprises the following steps: sequentially laminating an upper high-frequency microwave core board, an RT6002 board, a prepreg, a first copper plate, a conductive adhesive layer, a second copper plate and a lower high-frequency microwave core board to form a PCB;

step two: arranging a cavity on the PCB obtained in the step one, wherein the position of the cavity is provided with a conductive adhesive layer and a red copper plate I on the upper layer of the conductive adhesive layer;

step three: step blind grooves are formed in the PCB obtained in the step one;

step four: and C, manufacturing coaxial radio frequency transmission holes, through holes and blind holes in the PCB obtained in the step I.

As a further scheme of the invention: the upper-layer high-frequency microwave core board is an RT5880 multilayer board, and the RT5880 multilayer board is formed by pressing three RT5880 board layers;

the lower-layer high-frequency microwave core plate is an RT6002 multilayer plate, and the RT6002 multilayer plate is formed by pressing two RT6002 plate layers.

As a further scheme of the invention: the cavity is a closed cavity after vacuum pressing, and the depth of the cavity is the sum of the thickness of the first red copper plate and the thickness of the conductive adhesive layer.

As a further scheme of the invention: the step blind groove is formed by downwards arranging the top of the PCB, and the bottom of the step blind groove is positioned on the upper surface of the red copper plate.

As a further scheme of the invention: the coaxial radio frequency transmission hole comprises a micro-strip line layer above the first copper plate and a radio frequency signal transmission hole of a micro-strip line layer below the second copper plate, the radio frequency signal transmission hole is positioned in the middle of a signal shielding hole formed by the first copper plate and the second copper plate, and the signal shielding hole is coaxial with the radio frequency signal transmission hole.

As a further scheme of the invention: and the prepregs or the conductive adhesive layers used in the intermediate layers of the stepped blind grooves and the cavity are subjected to windowing treatment, and the prepregs or the conductive adhesive layers are enlarged by 0.5mm compared with the whole size of the stepped blind grooves or the cavity.

As a further scheme of the invention: the through hole is a hole for connecting the copper foil circuit layer from the top to the bottom of the PCB.

As a further scheme of the invention: the blind hole is a hole for connecting the top of the PCB or the bottom of the PCB to the middle copper foil circuit layer of the PCB.

As a further scheme of the invention: the PCB is a multilayer rigid printed circuit board, and the number of designed circuit layers of the PCB is 10.

As a further scheme of the invention: the first copper plate and the second copper plate have a heat dissipation function.

As a further scheme of the invention: the prepreg is FR-28-0040-50.

As a further scheme of the invention: the conductive adhesive layer is ABLESTIK CF 3350-004.

As a further scheme of the invention: the cavity is a cubic cavity structure with the length and width of 5.0 x 5.0mm and the depth of 1.1 mm.

As a further scheme of the invention: the blind groove of two kinds of degree of depth is seted up by the bottom to the ladder blind groove from PCB board top surface, exposes the upper surface of a PCB board purple copper board top microstrip line layer and purple copper board respectively, and the position of seting up that exposes a purple copper board upper surface blind groove sets up for exposing the inside of microstrip line layer blind groove, forms the ladder groove structure of groove in the groove.

As a further scheme of the invention: the diameter of the radio frequency signal transmission hole is less than or equal to 1.0mm, and the diameter of the signal shielding hole is 1.6 mm.

As a further scheme of the invention: the thickness of the first copper plate is 1.0mm, and the thickness of the second copper plate is 2.5 mm.

As a further scheme of the invention: the high frequency of the PCB board is a dual-band design of 32GHz and 18 GHz.

As a further scheme of the invention: the ultra-low loss of the PCB is designed by utilizing a vacuum cavity, and the interlayer dielectric constant value is close to the value 1.0 in the vacuum state.

The invention has the beneficial effects that:

(1) the invention adopts Ka and Ku dual-frequency band signal transmission design, and can remarkably improve the transmission speed of signals and reduce the loss by adopting the design of embedding a vacuum cavity for meeting the transmission quality requirement of the signals;

(2) according to the invention, the copper plate is embedded in the intermediate layer, and the grounding hole is connected with the copper plate, so that the heat dissipation efficiency of the PCB can be obviously improved, and the stability of a product is improved;

(3) the coaxial hole design is adopted for the high-frequency transmission hole, so that the shielding and anti-interference of signals can be carried out to the maximum extent, and the stable transmission and transition of the signals are realized.

Drawings

The invention will be further described with reference to the accompanying drawings.

FIG. 1 is a front view of the present invention;

FIG. 2 is a schematic structural view of a PCB board stack of the present invention;

fig. 3 is a partially enlarged view of fig. 2.

In the figure: 1. a first red copper plate; 2. a red copper plate II; 3. a conductive adhesive layer; 4. an upper high-frequency microwave core board; 5. a lower high-frequency microwave core board; 6. RT6002 plates; 7. a prepreg; 8. a stepped blind groove; 9. a coaxial radio frequency transmission aperture; 10. blind holes; 11. a through hole; 12. a cavity.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-3, the present invention is a method for manufacturing a high frequency printed circuit board with ultra-low loss and high heat dissipation, which comprises the following steps:

the method comprises the following steps: pressing an RT6002 plate 6 with the medium thickness of 0.254mm and a red copper plate I1 into a daughter plate I by adopting FR-28-0040-50;

step two: a cavity 12 is formed in the first daughter board 1 in the first step, and the cavity 12 is of a cubic cavity structure with the length, the width and the depth of 5.0 multiplied by 5.0mm and 1.1 mm;

the cavity 12 is a vacuum cavity, and the opening direction of the cavity 12 is controlled from the red copper plate 1 to the mid 7 layer direction, so that the mid 7 medium layer is exposed (the mid 7 copper foil is completely removed);

step three: pressing, curing and bonding the daughter board I and the red copper plate II 2 into a daughter board II by using conductive adhesive, and pressing the conductive adhesive to form a conductive adhesive layer 3;

the opening size of the conductive adhesive layer 3 corresponding to the position of the cavity 12 formed in the red copper plate 1 is formed by integrally enlarging the size of the cavity 12 by 0.5 mm;

the daughter board II is pressed in a vacuum compressor through the conductive adhesive layer 3 to form a vacuum cavity 12;

step four: drilling the daughter board II to form holes from mid 6 to the lower surface of the red copper plate II 2, and plugging the machined holes in a vacuum manner by adopting thermosetting resin;

the diameter of the processed hole is 1.6 mm;

step five: drilling a radio frequency signal transmission hole on the daughter board II after the vacuum hole plugging operation is finished, performing resin vacuum hole plugging on the aperture of the radio frequency signal transmission hole, and plugging the hole tightly;

the radio frequency signal transmission hole and the signal shielding hole in the step four are coaxially designed to form a coaxial radio frequency transmission hole 9, and the diameter of the hole is 0.4 mm;

step six: carrying out vacuum pressing and bonding on the bottom surface of the daughter board II and the lower-layer high-frequency microwave core board 5 by adopting FR-28-0040-50 to form a daughter board III;

the daughter board III is a printed circuit board from mid 6 to the top surface of the PCB, the lower-layer high-frequency microwave core board 5 comprises two dielectric substrates, and one FR-28-0040-50 is used for bonding between the dielectric substrate and the daughter board II and between the dielectric substrate and the dielectric substrate;

step six, the dielectric substrate is an RT6002 board 6, and drilling (mid 10 to the bottom layer) and metallizing the through hole 11 of the layer are separately performed on the dielectric substrate from mid 10 to the bottom layer of the PCB before lamination;

step seven: drilling and metallizing the holes of the daughter board III, and plugging the two types of holes with resin in a vacuum manner;

the drilling holes in the seventh step are holes from mid 6 to the bottom surface of the PCB and blind holes 10 from the lower surface of the red copper plate 2 to the bottom surface of the PCB, and hole metallization is adopted to obtain metallized holes from mid 6 to the bottom surface of the PCB and the metallized blind holes 10 from the lower surface of the red copper plate 2 to the bottom surface of the PCB;

step eight: pressing the top surfaces of the daughter boards and the upper-layer high-frequency microwave core board 4 to form a PCB;

the upper-layer high-frequency microwave core board 4 comprises three dielectric substrates, the dielectric substrates are RT5880 boards, the PCB boards are daughter boards three and three dielectric substrates, FR-28-0040-50 is semi-cured for lamination, and one FR-28-0040-50 is semi-cured for vacuum lamination and bonding between each dielectric substrate and between the dielectric substrate and the daughter board three to form a whole;

step nine: drilling, metallizing and back-drilling the PCB;

the drilling is a through hole 11 from the top surface of the PCB to the bottom surface of the PCB, and chemical copper deposition and electrolytic copper plating are adopted to obtain a metalized through hole 11;

the back drill adopts an operation mode of mechanical depth control drilling to perform drilling operation from the bottom surface of the PCB to the mid 10 direction, and removes part of copper from the mid 10 to the bottom surface of the PCB in the through hole 11 from the top surface of the PCB to the bottom surface of the PCB, so as to form the conduction of metallized holes from the top surface of the PCB to the bottom surface of the PCB;

the depth of the back drilling hole is the thickness between the bottom surface of the PCB and mid 10, a mid 10 copper layer is not drilled during back drilling operation, and the depth is controlled to be 0.05mm-0.075mm from the bottom surface of the PCB by the mid 10 copper layer;

step ten: forming a stepped blind slot 8 on the PCB;

the step blind groove 8 is of two blind groove structures from the top surface of the PCB to mid 6 and from the top surface of the PCB to the first copper plate 1, and the blind groove opening position from the top surface of the PCB to the first copper plate 1 is arranged between the top surface of the PCB and the mid 6 blind groove to form a groove-in-groove structure;

step eleven: processing the surface of the PCB board and the surface of the graph inside the stepped blind slot 8 by using electroless nickel-gold;

step twelve: and C, carrying out mechanical forming processing on the PCB subjected to the nickel-gold chemical deposition in the step eleven to obtain a required designed PCB product.

Wherein, the prepreg 7 is FR-28-0040-50.

The stepped blind groove 8 comprises a first blind groove and a second blind groove, the second blind groove is projected in the vertical direction and is located inside the first blind groove, and copper circuit patterns are arranged on the first blind groove and the second blind groove.

While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.