CN112105150B

CN112105150B - Manufacturing method of embedded cavity and PCB

Info

Publication number: CN112105150B
Application number: CN202011215062.6A
Authority: CN
Inventors: 吴泓宇; 刘梦茹; 肖璐; 纪成光
Original assignee: Shengyi Electronics Co Ltd
Current assignee: Shengyi Electronics Co Ltd
Priority date: 2020-11-04
Filing date: 2020-11-04
Publication date: 2021-08-13
Anticipated expiration: 2040-11-04
Also published as: CN112105150A

Abstract

The invention relates to the technical field of PCBs (printed circuit boards), and discloses a manufacturing method of an embedded cavity and a PCB. The manufacturing method comprises the following steps: providing first core and second core, covering the circuit shielding film toward the cavity area of first core, laminating first core and second core into an auxiliary board through prepreg layer set up on the auxiliary board and contain the lid the ladder groove in cavity area to get rid of the circuit shielding film, the preparation supports the opening of apron with shutoff ladder groove, forms inclosed cavity. According to the invention, a low-fluidity prepreg is not needed, so that the heat-resisting reliability of the PCB is not reduced, and meanwhile, the flowing glue of the prepreg does not influence the appearance formation of the cavity, so that a glue-blocking pattern with higher precision requirement does not need to be prepared, the manufacturing method is simpler and more reliable, and the prepared cavity has good appearance.

Description

Manufacturing method of embedded cavity and PCB

Technical Field

The invention relates to the technical field of Printed Circuit Boards (PCBs), in particular to a manufacturing method of an embedded cavity and a PCB.

Background

With the rapid advance of information industry and electronic industry represented by intelligent electronic products, digital circuits gradually enter the stages of information processing high speed and signal transmission high frequency, and the whole electronic system is developed towards the directions of lightness, thinness, shortness, multifunction, high density, high reliability and low cost; with the development of the communication electronics field toward high frequency and high speed of signals, higher requirements are put forward on low loss transmission, impedance continuity and the like of high frequency and high speed signals of signal lines in the PCB. Therefore, higher and more urgent requirements are put forward on the low dielectric property of the copper-clad plate; the realization of low dielectric constant (Dk) and low dielectric loss factor (Df) of PCB substrate materials has become the mainstream technology and power for the development of the whole industry, but has not been developed in a breakthrough way.

Because the dielectric constant and the dielectric loss of the air are far lower than the Dk and Df values of the conventional resin base plate of the PCB at present, the design of embedding the closed cavity in the PCB can improve the signal transmission speed of the circuit board and further reduce the signal loss.

However, embedding the cavity inside the PCB has certain difficulty, and currently, in order to control the flow inside the closed cavity and the shape of the cavity, most of the designs use a prepreg with low fluidity for lamination. The current practice in the industry is to manufacture the embedded cavity of the PCB by vertically pressing the core board after the low fluidity bonding sheet is provided with the through groove, or by coating a developable mask layer on the core board in cooperation with vertically pressing the core board by the low fluidity bonding sheet. Even in the low fluidity bonding sheet, the flow rate is generally over 10mil, the cavity is irregular due to the flow, and the low fluidity bonding sheet has poor heat resistance reliability and risks of alignment deviation and the like.

The patent with the application number of CN201511029287.1 and the name of PCB manufacturing method provides a new design idea, which adopts the steps of forming holes on an inner core plate, manufacturing glue blocking protrusions on the end face of the inner core plate by using printing ink, and laminating a common prepreg to manufacture the PCB with an embedded cavity. This patent scheme is better for the mode that adopts low fluidity bonding piece, and the reliability, nevertheless its in-process at the pressfitting prepreg, because of the gummosis is not well controlled, hinders that the design of gluey bellied size and height is difficult to carry out accurate matching, has the error a little, just can lead to the gummosis to get into the cavity, and this method of preparing the cavity requires very high to the figure design precision that hinders gluey, and the operation degree of difficulty is great.

Therefore, the method for manufacturing the buried cavity PCB is further optimized, and the glue flow inside the cavity and the appearance of the cavity are effectively controlled, which is a technical problem to be solved in the field.

Disclosure of Invention

The invention aims to provide a manufacturing method of an embedded cavity and a PCB (printed Circuit Board), which overcome the defect of irregular cavity in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a method for manufacturing an embedded cavity, the method comprising:

providing a plurality of core plates; the core plates include a first core plate and a second core plate; a cavity area is preset on the surface of the first copper foil layer of the first core board, and a preset circuit pattern is manufactured in the cavity area;

covering a circuit shielding film on the cavity area;

laminating the first core plate and the second core plate into a sub-plate through a prepreg layer;

a step groove which covers the cavity area is formed in the daughter board, and the circuit shielding film is removed; the stepped groove extends from the surface of the first copper foil layer of the second core plate to the first core plate;

and manufacturing a supporting cover plate, and plugging the opening of the stepped groove to form a closed cavity.

Optionally, the steps of: set up on the daughter board and cover the ladder groove in cavity district, and get rid of the circuit shielding film specifically includes:

the stepped grooves are deeply processed on the daughter boards from the surface of the first copper foil layer of the second core board along the stacking direction; the stepped grooves comprise a first stepped groove and a second stepped groove extending from the groove bottom of the first stepped groove to the first core plate, and the second stepped groove covers the cavity area;

and removing the daughter board waste material generated in the depth control processing process together with the circuit shielding film to expose the preset circuit pattern.

Optionally, the steps of: the preparation supports the apron, makes its shutoff the opening in ladder groove forms inclosed cavity, specifically includes:

manufacturing a supporting cover plate matched with the shape of the first stepped groove;

and embedding the supporting cover plate into the first stepped groove, wherein the supporting cover plate and the second stepped groove are surrounded to form the cavity.

Optionally, the depth of the first step groove is equal to the thickness of the second core plate.

Optionally, the thickness of the supporting cover plate is equal to the depth of the first stepped groove.

Optionally, the sub-board includes a first side and a second side distributed along the stacking direction;

the steps are as follows: the preparation supports the apron, makes its shutoff the opening of ladder groove forms inclosed cavity after, still includes:

laminating the core board on the first side and/or the second side of the daughter board through a prepreg layer respectively to obtain a mother board;

and laminating the mother board and the core boards through the prepregs according to a preset sequence to obtain the multilayer board.

Optionally, the circuit shielding film is a high-temperature-resistant adhesive tape or an ink film attached to the cavity region.

Optionally, the high-temperature resistant adhesive tape is strip-shaped; the preset circuit pattern is arranged along the length direction of the high-temperature-resistant adhesive tape and is positioned in the middle of the high-temperature-resistant adhesive tape.

Optionally, the supporting cover plate is made of a core plate, an insulating plate, a multilayer plate or a copper plate.

In a second aspect, the present invention provides a PCB having a closed cavity embedded therein, wherein the cavity is made according to any one of the above-mentioned manufacturing methods.

Compared with the prior art, the invention has the beneficial effects that:

by applying the embodiment of the invention, the PCB with the embedded cavity can be manufactured, and in the manufacturing process, a low-fluidity prepreg is not needed, so that the heat-resisting reliability of the PCB is not reduced, meanwhile, the flowing glue of the prepreg does not influence the appearance formation of the cavity, so that a glue-blocking pattern with higher precision requirement is not needed to be prepared, the manufacturing method is simpler and more reliable, the manufactured cavity has good appearance, and the alignment precision of the cavity and a circuit is high.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

Fig. 1 is a flowchart of a method for manufacturing an embedded cavity according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a daughter board provided in an embodiment of the present invention before lamination;

fig. 3 is a schematic structural diagram of a daughter board provided in an embodiment of the present invention after being bonded;

fig. 4 is a schematic structural diagram of the daughter board provided in the embodiment of the present invention after the depth control processing process;

fig. 5 is a schematic structural diagram of a daughter board provided in an embodiment of the present invention when the daughter board waste and the line shielding film are removed;

FIG. 6 is a schematic structural diagram of a daughter board according to an embodiment of the present invention before a first step groove is embedded in a supporting cover plate;

fig. 7 is a schematic structural diagram of a motherboard according to an embodiment of the present invention.

In the figure:

10. a core board; 11. a first core board; 111. a cavity area; 112. presetting a circuit pattern; 12. a second core board; 20. a circuit shielding film; 30. a prepreg; 40. daughter board scrap; 50. a stepped groove; 51. a first step groove; 52. a second stepped groove; 60. a support cover plate; 70. a cavity.

Detailed Description

In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below 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.

The first embodiment is as follows:

referring to fig. 1 and 2, the present embodiment provides a method for manufacturing an embedded cavity, including the steps of:

step 100, providing a plurality of core plates 10;

in this step, the core plate 10 includes a first core plate 11 and a second core plate 12; a cavity area 111 is preset on the surface of the first copper foil layer of the first core board 11, and a preset circuit pattern 112 is manufactured in the cavity area 111; the predetermined wiring pattern 112 includes high-frequency signal lines.

The surface of the first copper foil layer of the first core board 11 is the upper surface of the first core board 11 in fig. 2.

Step 110, covering a circuit shielding film 20 to the cavity region 111;

in this embodiment, the circuit shielding film 20 is a high temperature resistant tape attached to the cavity area 111 or an ink film coated on the cavity area, and is used for covering the predetermined circuit pattern 112.

As a preferred embodiment, the line shielding film 20 is made of a long high temperature resistant tape; the predetermined circuit pattern 112 is disposed along a length direction of the high temperature resistant adhesive tape, the high temperature resistant adhesive tape includes a central line distributed along the length direction, and the predetermined circuit pattern 112 is located near the central line of the high temperature resistant adhesive tape.

Step 120, laminating the first core board 11 and the second core board 12 through the prepreg 30 to form a sub-board;

referring to fig. 3, in the embodiment, the circuit shielding film 20 can function as a glue blocking film and protect the circuit, and since the cavity region 111 is covered by the circuit shielding film 20, the glue flowing from the prepreg 30 is blocked and cannot enter the cavity region 111 during the pressing process.

Step 130, forming a stepped groove 50 covering the cavity region 111 on the daughter board, and removing the line shielding film 20;

referring to fig. 4-6, the step groove 50 in this step is a two-stage step groove extending from the surface of the first copper foil layer of the second core plate 12 to the first core plate 11; in fig. 3, the first copper foil layer surface of the first core board 11 is disposed facing the second core board 12, and the first copper foil layer surface of the second core board 12 is a copper foil layer surface of the second core board 12 away from the first core board 11;

specifically, the stepped groove 50 includes a first stepped groove 51 and a second stepped groove 52 extending from the groove bottom of the first stepped groove 51 to the first core plate 11; cavity region 111 is contained within second step groove 52, and more specifically, cavity region 111 is located within the area enclosed by the groove bottom boundary of second step groove 52;

as a specific implementation manner of this embodiment, step 130 includes:

step grooves 50 are deeply processed on the daughter boards from the surface of the first copper foil layer of the second core board 12 along the stacking direction; the stepped groove 50 includes a first stepped groove 51 and a second stepped groove 52 extending from the groove bottom of the first stepped groove 51 to the first core plate 11, the second stepped groove 52 including a cavity region 111;

removing the daughter board waste 40 generated in the depth control processing process together with the circuit shielding film 20 to expose a predetermined circuit pattern 112;

wherein, the depth D2 of the stepped groove 50 is the sum of the depth D1 of the first stepped groove 51 and the depth of the second stepped groove 52; the groove bottom of the second step groove 52 extends to the first core plate 11. In the present embodiment, D1 is equal to the thickness of the second core plate 12.

It should be noted that in this step, a milling machine or a laser cutting machine and other devices may be used for depth control processing, which all belong to conventional technical means in the field and are not described herein again.

Step 140, manufacturing the supporting cover plate 60 to plug the opening of the stepped groove 50 to form a closed cavity.

Referring to fig. 7, step 140 specifically includes:

step 141, manufacturing a supporting cover plate 60 matched with the shape of the first stepped slot 51;

in this embodiment, the supporting cover plate 60 may be made of a core plate, an insulating plate, a multi-layer plate, or a copper plate. As a preferred embodiment, the thickness of the support cover plate 60 is equal to the thickness of the second core plate 12.

And 142, embedding the supporting cover plate 60 into the first stepped groove 51, and enclosing the supporting cover plate 60 and the second stepped groove 52 to form a closed cavity 70.

In this embodiment, as an optional implementation scheme, support apron 60 and first step groove 51 are interference fit, and is concrete, and first step groove 51 is square groove, can all form the circular arc chamfer in each right angle inboard of first step groove 51, supports apron 60 and is embedded into first step groove 51 back, supports apron 60 and takes place deformation, and the deformation part is laminated in the circular arc chamfer, further ensures to support apron 60 and first step groove 51 fixed connection's stability.

In this embodiment, as another optional implementation, the supporting cover plate 60 is in clearance fit with the first step groove 51, and in this step, the prepreg 30 and the core plate 10 are sequentially laminated and pressed on the side of the supporting cover plate 60 away from the daughter board, so that the supporting cover plate 60 is limited in the first step groove 51.

150, laminating a core board 10 on the first side and/or the second side of the daughter board respectively through prepregs 30 to obtain a mother board;

wherein, the first side and the second side of the daughter board are two sides of the daughter board distributed along the stacking direction.

And 160, laminating and pressing the mother board and the core boards 10 through the prepregs 30 according to a preset sequence to obtain the multilayer board.

Then, the required PCB with the embedded cavity 70 is finally manufactured by performing the outer layer pattern manufacturing and other post-process manufacturing processes.

In the embodiment of the invention, in the process of manufacturing the cavity 70, the common prepreg 30 is adopted, so that the heat-resisting reliability of the PCB is not sacrificed, and meanwhile, the gummosis of the prepreg 30 does not influence the appearance formation of the cavity 70, so that a gummosis resisting pattern with higher precision requirement does not need to be prepared, the manufacturing method is simpler and more reliable, the manufactured cavity 70 has good appearance, and the alignment precision of the cavity 70 and a circuit is high.

Example two:

the present embodiment further provides a PCB, wherein a closed cavity 70 is embedded inside the PCB, and the cavity 70 is manufactured according to the manufacturing method provided in the first embodiment.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will 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 such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A manufacturing method of an embedded cavity is characterized by comprising the following steps:

providing a plurality of core plates; the core plates include a first core plate and a second core plate; a cavity area is preset on the surface of the first copper foil layer of the first core board, and a preset circuit pattern is manufactured in the cavity area; the surface of the first copper foil layer of the first core board is arranged facing the second core board, and the surface of the first copper foil layer of the second core board is the surface of a copper foil layer of the second core board far away from the first core board;

covering a circuit shielding film on the cavity area;

2. The method for fabricating an embedded cavity according to claim 1, wherein the steps of: set up on the daughter board and cover the ladder groove in cavity district, and get rid of the circuit shielding film specifically includes:

3. The method for fabricating the buried cavity according to claim 2, wherein the steps of: the preparation supports the apron, makes its shutoff the opening in ladder groove forms inclosed cavity, specifically includes:

4. The method of claim 2, wherein the depth of the first step groove is equal to the thickness of the second core plate.

5. The method of claim 2, wherein the thickness of the supporting cover plate is equal to the depth of the first stepped groove.

6. The method of claim 1, wherein the daughter board includes a first side and a second side along a stacking direction;

laminating and pressing the core board on the first side and/or the second side of the daughter board through prepregs respectively to obtain a mother board;

7. The method as claimed in claim 1, wherein the circuit shielding film is a high temperature resistant tape or ink film attached to the cavity region.

8. The method for manufacturing an embedded cavity according to claim 7, wherein the high temperature resistant adhesive tape is strip-shaped; the preset circuit pattern is arranged along the length direction of the high-temperature-resistant adhesive tape and is positioned in the middle of the high-temperature-resistant adhesive tape.

9. The method of claim 1, wherein the supporting cover plate is made of a core plate, an insulating plate, a multi-layer plate or a copper plate.

10. A PCB having a closed cavity embedded therein, wherein the cavity is manufactured according to the method of any one of claims 1 to 9.