WO2011150738A1

WO2011150738A1 - Circuit board and manufacturing method thereof

Info

Publication number: WO2011150738A1
Application number: PCT/CN2011/074076
Authority: WO
Inventors: 高峰; 刘山当; 宗晅
Original assignee: 华为技术有限公司
Priority date: 2010-11-25
Filing date: 2011-05-16
Publication date: 2011-12-08
Also published as: MX2011013097A; BRPI1105246A2; BRPI1105246B1; HUP1200255A2; HU230941B1; CN102143647A; CN102143647B

Abstract

A circuit board (100) and a manufacturing method thereof are provided. The circuit board (100) comprises at least one adhesive layer (120) and at least one transmission line (140), an air cavity (124) is formed in the adhesive layer (120), and an orthographic projection of the transmission line (140) is located in the area of the air cavity (124) of the adhesive layer (120).

Description

Circuit board and manufacturing method thereof

The present application claims priority to Chinese Patent Application No. 201010564278.3, entitled "A Circuit Board and Its Making Method", filed on November 25, 2010, the entire contents of in.

Technical field

The present invention relates to a circuit board, and more particularly to a circuit board having a higher signal transmission quality and a method of fabricating the same.

Background technique

With the rapid development of large-scale integrated circuits, the requirements for data transmission rates are increasing. At present, data transmission rates can reach 100 Gbps, and data transmission rates of 200 Gbps, 400 Gbps, and even higher will be realized in the near future. In order to achieve high transfer rates, the requirements for printed circuit board (PCB) materials are very high, and PCBs are usually required to have low dielectric constant Df and low dielectric loss Dk characteristics. At present, the means for reducing the Df and Dk of PCB boards are mainly modified from glass fiber and resin systems, such as ceramic filling, flat glass fiber, and non-epoxy resin (PTFE). However, most of the sheets with Df < 0.003 are PTFE materials, which is not conducive to the processing of PCB multi-layer boards; in addition, the materials of low Dk and Df are very expensive, resulting in very high cost of the products.

Summary of the invention

In view of this, embodiments of the present invention provide a low-cost circuit board, and a method of fabricating the circuit board.

A circuit board comprising at least one bonding layer and at least one transmission line, wherein an air cavity is formed in the bonding layer, and an orthographic projection of the transmission line falls in a region where an air cavity of the bonding layer is located.

A method of manufacturing a circuit board, comprising the steps of:

Providing a core board, the core board comprising a dielectric layer, and a conductive medium covering at least one side of the dielectric layer;

Forming a transmission line on the conductive medium on one side of the core board;

Providing another core board, the core board comprising a dielectric layer, and a conductive medium covering at least one side of the dielectric layer;

Providing a bonding layer on the conductive medium on one side of the core board;

Opening a groove for forming an air cavity on the bonding layer; Laminating the core sheet formed with the transmission line and the bonding around the slot forms the air cavity, and aligning the orthographic projection of the transmission line with the air cavity.

In the circuit board and the electric board manufacturing method provided by the embodiments of the present invention, by providing an air cavity in the bonding layer of the circuit board, the characteristics of Dk and Df of the entire circuit board are reduced by utilizing the characteristics of low Df and low Dk of air. Thereby, the signal transmission quality of the circuit board is improved; in addition, the step of providing the air cavity on the bonding layer is easy to implement, thereby reducing the manufacturing cost of the circuit board.

DRAWINGS

1 is a schematic diagram of a circuit board according to a first embodiment of the present invention;

2 is a schematic diagram of another structure of a circuit board according to a first embodiment of the present invention; FIG. 3 is a schematic diagram of a circuit board according to a second embodiment of the present invention;

4 is a schematic diagram of a circuit board according to a third embodiment of the present invention;

FIG. 5 is a schematic diagram of a circuit board according to a fourth embodiment of the present invention; FIG.

FIG. 6 is a schematic diagram of a circuit board according to a fourth embodiment of the present invention.

detailed description

The embodiments of the present invention are described in detail below with reference to the accompanying drawings and specific embodiments.

The circuit board 100 provided by the embodiment of the present invention includes at least one circuit board unit composed of the bonding layer 120 and the transmission line 140. An air cavity 124 is formed on the bonding layer 120 of each of the circuit board units, and an orthographic projection of the transmission line 140 falls in a region where the air cavity 124 of the bonding layer 120 is located.

Referring to FIG. 1 , a circuit board 100 is provided by an embodiment of the present invention. The circuit board 100 is composed of a circuit board unit. The circuit board unit includes a reference layer 110, the bonding layer 120, and at least one dielectric layer. 130 and the transmission line 140 described. The adhesive layer 120 is provided with adhesive layers 120 corresponding to the circumferences to be pressed against each other to form the air chamber 124. The transmission line 140 is disposed on the dielectric layer 130 and its orthographic projection falls in the area where the air cavity 124 is located.

The reference layer 110 is made of a conductive material, and the reference layer 110 in the embodiment is a copper foil. The reference layer 110 includes a first surface 112 and a second surface 114 corresponding to the first surface 112. In order to increase the mechanical strength of the reference layer 110, a reinforcing layer 150 is further disposed on the second surface 114 of the reference layer 110, and the reinforcing layer 150 may be made of an insulating material.

One side of the bonding layer 120 is bonded to the first surface 112 of the reference layer 110. Real In the embodiment, the adhesive layer 120 is made of a material colloid having a strong adhesive property and a low amount of glue, for example, a polyimide having a glue layer or a photosensitive resin. In this embodiment, the width of the slot 122 formed on the bonding layer 120 is wider than the width of the transmission line 140, and the projection of the transmission line 140 may fall into the slot 122, and this embodiment The width of the slot 122 is 0.2 mm to 0.3 mm wider than the width of the transmission line 140.

The dielectric layer 130 is made of an insulating material. The dielectric layer 130 includes an upper surface 132 and a lower surface 134 corresponding to the upper surface 132. The dielectric layer 130 is bonded to the other side of the bonding layer 120 through its lower surface 134.

In this embodiment, the transmission line 140 is disposed on the lower surface 134 of the dielectric layer 130 and is received in the air cavity 124. In the circuit board unit of such a structure, the dielectric layer may also be A ground layer 160 is disposed on the upper surface of the substrate 130. The ground layer 160 is made of a conductive material. In this embodiment, the ground layer 160 is made of copper foil.

It will be understood that the transmission line 140 may also be formed on the upper surface 132 of the dielectric layer 130 as shown in FIG.

The circuit board 100 provided in the embodiment of the present invention reduces the dielectric constant and the medium of the circuit board 100 by forming the air cavity 124 facing the transmission line 140 on the bonding layer 120, utilizing the characteristics of the low Df and Dk of the air. The loss, the transmission quality of the signal is improved; in addition, the manufacturing process of forming the air cavity 124 on the bonding layer 120 to form the air cylinder 124 is easy to implement, thereby reducing the manufacturing cost.

Referring to FIG. 3 , a circuit board 200 is provided in a second embodiment of the present invention. The circuit board 200 includes a plurality of circuit board units that are sequentially stacked. Specifically, the circuit board 200 includes the circuit in the first embodiment. The structure of the board 100 is substantially the same as that of the first circuit board unit 200a, the second circuit board unit 200b, and the third circuit board unit 200c. The reference layer 210b of the second circuit board unit 200b is disposed on the dielectric layer 240a of the first circuit board unit 200a; the reference layer 210c of the third circuit board unit 200c is disposed on the medium of the second circuit board unit 200b On layer 240b. It can be understood that, in this embodiment, only three sets of circuit board units 200a, 200b, and 200c having substantially the same structure are combined with each other to form a multi-layer circuit board as an example to illustrate how to construct a plurality of air chambers by using a plurality of circuit board units. The structure of the layer circuit board, but the number of layers of the circuit board 200 is not limited to the number of superpositions shown in this embodiment. This evening, In this embodiment, the dielectric layer 240c of the third circuit board unit 200c, that is, the outermost circuit board unit is exposed on the outer dielectric layer, and a ground layer 260 may be disposed.

Referring to FIG. 4, a circuit board 300 according to a third embodiment of the present invention includes a circuit board unit including a sub-circuit board 310, a secondary bonding layer 320, and a second time. Reference layer 330, and a secondary dielectric layer 340.

The sub-board 310 has the same structure as the circuit board 100 in the first embodiment, and includes a reference layer 311, a bonding layer 312, a dielectric layer 313, and a transmission line 314. The difference is that the dielectric layer 313 has a thin structure, that is, the thickness of the dielectric layer 313, the dielectric layer 340, which is the thickness of the dielectric layer in the embodiment is 2 mils.

The secondary bonding layer 320 is disposed outside the dielectric layer 313 of the circuit board 310, and the second bonding layer 320 is provided with another slot 322 opposite to the transmission line 314 of the sub-board 310. Another air cavity 324 is formed in the bonding layer 320. The orthographic projection of the transmission line 314 falls within the other air cavity 324.

The secondary dielectric layer 340 is disposed on the secondary reference layer 330.

The circuit board 300 provided in this embodiment can further reduce the dielectric constant and dielectric loss of the circuit board 300 by using an air cavity on both sides of the transmission line 314 to further reduce the characteristics of the air Dk and Df. Thereby improving the transmission quality of the signal.

Referring to FIG. 5, a circuit board 400 according to a fourth embodiment of the present invention includes a plurality of circuit board units that are sequentially stacked, and the circuit board unit and the circuit board 300 structure in the third embodiment. Similarly, it includes a first circuit board unit 400a, and a second circuit board unit 400b. The reference layer 411b of the second circuit board unit 400b is disposed on the sub-dielectric layer 440b of the first circuit board unit 400a to constitute a multi-layer circuit board structure.

Please refer to FIG. 6 for a circuit board manufacturing method provided by the present invention.

It includes the following steps:

Step 1: providing a core board 500, the core board 500 includes a dielectric layer 510, and a conductive medium 512 covering at least the side of the dielectric layer 510;

In this step, the core plate 500 may be made of FR4® or ceramic filled or PTFE® type core material, wherein the conductive medium 512 may be copper foil. Forming a transmission line 540 on the conductive medium 512 on one side of the core board 500;

In this step, the formation of the transmission line 540 can be implemented by chemical etching or physical etching.

Step 2: providing another core board 500, the core board 500 includes a dielectric layer 510, and a conductive medium 512 covering at least the side of the dielectric layer 510; a sticky layer is disposed on the conductive medium 512 on the side of the core board 500 Connection layer 520;

Step 3: opening a groove 522 for forming an air cavity 524 on the bonding layer 520;

In the step, the slit 522 may be formed by a method such as laser forming, development molding or mold pre-forming; when forming the slit 522, it is required to be on the conductive medium 512 corresponding to the slit 522, that is, There is no glue residue on the bottom of the air chamber 524.

Step 4: The core plate 500 formed with the transmission line 540 is superposed on the bonding layer 520 around the slot 522 to form the air cavity 514, and the orthographic projection of the transmission line 510 and the air cavity 524 is right.

It will be understood that the method of fabricating the board further includes the steps of repeating the above-described fabrication steps to form various multilayer circuit boards as provided in the embodiments of the present invention.

In the circuit board manufacturing method provided by the embodiment of the present invention, by providing an air cavity 524 corresponding to the transmission line 540 on the bonding layer 520 of the circuit board, the lower Dk and Df characteristics of the air are used to reduce the entire The Dk and Df characteristics of the circuit board improve the signal transmission quality of the circuit board. Further, the step of providing the air cavity 524 on the bonding layer 520 is easy to implement, thereby reducing the manufacturing cost of the circuit board.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., which are within the spirit and scope of the present invention, should be included in the protection of the present invention. Within the scope.

Claims

Rights request

A circuit board characterized in that

The circuit board includes at least one bonding layer and at least one transmission line;

An air cavity is formed in the bonding layer, and an orthographic projection of the transmission line falls in a region where the air cavity of the bonding layer is located.

2. The circuit board of claim 1 wherein:

The circuit board further includes a reference layer and a dielectric layer;

The bonding layer is provided with a groove corresponding to the transmission line, and the reference layer and the dielectric layer are respectively pressed against the bonding layer around the groove to form the air cavity.

3. The circuit board of claim 2, wherein

The width of the slot is greater than the width of the transmission line.

4. The circuit board of claim 2, wherein

The width of the groove is 0.2 mm to 0.3 mm wider than the width of the transmission line.

5. The circuit board of claim 2, wherein

The reference layer includes a first surface and a second surface corresponding to the first surface, the bonding layer is bonded on the first surface of the reference layer, and the circuit board further includes a reinforcement layer for The mechanical strength of the reference layer is increased, and the reinforcement layer is disposed on a second surface of the reference layer.

6. The circuit board of claim 2, wherein

The dielectric layer includes a lower surface and is bonded to the bonding layer through the lower surface, and the transmission line is disposed on a lower surface of the dielectric layer.

7. The circuit board according to claim 2, wherein a lower surface thereof is bonded to the bonding layer, and the transmission line is disposed on an upper surface of the dielectric layer.

8. The circuit board of claim 2, wherein

The circuit board further includes a secondary bonding layer, a secondary reference layer, and a secondary dielectric layer;

The secondary bonding layer is disposed outside the dielectric layer of the circuit board, and the secondary bonding layer is provided with another slot facing the orthographic projection of the transmission line of the sub-board, the second The reference layer and the dielectric layer are respectively pressed onto the secondary bonding layer around the other slot to form another air cavity, and the orthographic projection of the transmission line falls in the area where the other air cavity is located. The secondary medium layer is set in the secondary reference On the floor.

9. The circuit board of claim 8 wherein:

The reference layer includes a first surface and a second surface corresponding to the first surface, one side of the bonding layer is bonded on the first surface of the reference layer, and the circuit board further includes a reinforcing layer To increase the mechanical strength of the reference layer, the reinforcement layer is disposed on the second surface of the reference layer.

10. The circuit board of claim 8 wherein:

11. The circuit board according to claim 6 or 10, characterized in that

The transmission line is housed in the air cavity.

12. The circuit board of claim 9 wherein:

The dielectric layer is thinner than the secondary dielectric layer.

13. The circuit board of claim 1 wherein:

The circuit board includes at least two circuit board units composed of the at least one bonding layer and at least one transmission line, the circuit board units are sequentially overlapped with each other, wherein each of the circuit board units is in a bonding layer An air cavity is formed, and an orthographic projection of a transmission line of each of the circuit board units falls within the air cavity.

14. The circuit board of claim 13 wherein:

Each of the circuit board units further includes a reference layer and a dielectric layer, wherein the dielectric layer is integrated with the reference layer by the bonding layer, and the bonding layer is provided with a corresponding to the transmission line Slotting, the reference layer and the dielectric layer are respectively pressed against the bonding layer around the slot to form the air cavity, and the transmission line is disposed on the dielectric layer, wherein a reference layer of a circuit board unit is disposed On the dielectric layer of another board unit.

15. The circuit board of claim 13 wherein:

Each of the circuit board units further includes a reference layer, a dielectric layer, a secondary bonding layer, a secondary reference layer, and a secondary dielectric layer;

The dielectric layer is integrated with the reference layer by the bonding layer;

The bonding layer is provided with a slot corresponding to the transmission line, and the reference layer and the dielectric layer are respectively pressed against the bonding layer around the slot to form the air cavity; The transmission line is disposed on the dielectric layer;

The secondary bonding layer is disposed outside the dielectric layer of the circuit board;

Providing another slot corresponding to the transmission line on the secondary bonding layer;

The secondary reference layer is laminated with the medium on the secondary bonding layer around the other slot to form a secondary air cavity;

An orthographic projection of the transmission line falls within the secondary air cavity;

The secondary dielectric layer is disposed on the secondary reference layer;

The reference layer of one of the circuit board units is disposed on the secondary dielectric layer of the other circuit board unit.

16. A method of fabricating a circuit board, comprising the steps of:

Opening a groove for forming an air cavity on the bonding layer;

The core sheet on which the transmission line is formed is laminated to the periphery of the slot to form the air chamber, and the orthographic projection of the transmission line is aligned with the air chamber.

17. The method of fabricating a circuit board according to claim 16, wherein:

The groove on the bonding layer is formed by laser forming, development molding or mold pre-forming method