CN102143661B - Multi-layered circuit board and manufacturing method thereof - Google Patents

Abstract

The invention provides a method for manufacturing a multilayer circuit board, comprising the steps of: providing an inner layer board and an outer layer board; providing a film, the film is pre-opened with an opening area, and the opening area defines two parallel and opposite design reference lines , the edge area of the opening adjacent to each design reference line on the film is formed with a plurality of evenly and continuously arranged zigzag structures or a plurality of evenly and continuously arranged wavy structures protruding into the opening area; The film is placed between the inner layer board and the outer layer board, and the inner layer board and the outer layer board are rolled and thermally bonded by a first rolling device in a direction perpendicular to the design reference line; and a dry film is provided, The dry film is placed on the outer side of the outer layer board, and the dry film is thermally pressed to the outer layer board by using a second rolling device. The present invention also provides a multilayer circuit board manufactured by the method for manufacturing the multilayer circuit board.

Description

Multi-layer circuit board and its manufacturing method

technical field

The invention relates to circuit board technology, in particular to a multilayer circuit board with a specific adhesive layer structure and a manufacturing method thereof.

Background technique

With the rapid development of the electronic industry, the manufacturing technology of circuit boards, which are the basic components of electronic products, is becoming more and more important. The circuit board is generally made of a copper-clad substrate through a series of processes such as cutting, drilling, etching, exposure, development, pressing, and molding. For details, please refer to the article "Dielectric characterization of printed circuit board substrates" published by C.H.Steer et al. in Proceedings of the IEEE, Vol.39, No.2 (August 2002).

Generally, a multilayer circuit board can be formed by thermocompression bonding of an inner layer board and an outer layer board. A film is arranged between the inner layer board and the outer layer board, and after thermal pressing, the inner layer board and the outer layer board are closely adhered and fixed by the film, thereby forming a multilayer circuit board. Usually, an opening area is pre-opened on the film, and the opening area is mainly used to make the multilayer circuit board have proper flexibility in a specific area, so that the multilayer circuit board can be bent and applied to a specific electronic device. However, during the thermocompression bonding process of the outer layer board and the inner layer board, the film will soften due to heat and become a molten state. When the thickness of the film is 25 μm, the drop at the edge of the opening area is 25 μm), so the gas trapped between the film and the outer or inner plate stays at the opposite edges of the opening area and cannot escape in time. The gas forms bubbles after thermocompression. In the subsequent processing of the multilayer circuit board, the bubbles will expand under heat to form a raised area, which not only affects the appearance quality of the multilayer circuit board, but also makes the multilayer circuit board easy to cause delamination during subsequent processing or use, causing the circuit board fail. Moreover, during the subsequent dry film lamination process of the multilayer circuit board, the copper layer of the outer layer board may be disconnected at the opening area of the film due to the height difference, causing line breakage and affecting the conduction quality of the multilayer circuit board .

Therefore, in view of the above problems, it is necessary to provide a multilayer circuit board and a manufacturing method thereof that can effectively avoid the formation of air bubbles in the multilayer circuit board and prevent circuit breakage.

Contents of the invention

A multi-layer circuit board and its manufacturing method will be described below with specific embodiments.

A method for manufacturing a multilayer circuit board, comprising the following steps: providing an inner layer board and an outer layer board, the inner layer board including a first insulating layer and a first conductive layer disposed on at least one surface of the first insulating layer, The outer board includes a second insulating layer and a second conductive layer disposed on at least one surface of the second insulating layer; a film is provided, and an opening area is pre-opened on the film, and the opening area defines two parallel and opposite design references Lines, the edge area of the opening adjacent to each design reference line on the film is formed with a plurality of evenly and continuously arranged zigzag structures or a plurality of evenly and continuously arranged wavy structures protruding into the opening area; placing the film between the inner layer board and the outer layer board, and rolling and thermally bonding the inner layer board and the outer layer board using a first rolling device in a direction perpendicular to the design reference line; and providing a dry film , placing the dry film on the outer side of the outer layer board, and thermally bonding the dry film to the outer layer board by using a second rolling device.

A multi-layer circuit board, comprising an inner board, an outer board, a film and a dry film, the film is bonded between the inner board and the outer board, the film is provided with an opening area, and the opening area and the The edge area of the opening adjacent to the film has a buffer formed by the film, and the dry film is attached to the outer plate.

Compared with the prior art, in the multi-layer circuit board and its manufacturing method of the technical solution, an opening area is opened on the film, and a zigzag structure or The wavy structure makes the zigzag structure or wavy structure of the film form a buffer in the opening area after the inner plate and the outer plate are heat-pressed, so that the gas staying in the edge area of the opening can be effectively driven away to avoid the Bubble bulges are formed at the edge of the opening, which improves the appearance quality of the multilayer circuit board and effectively prevents the multilayer circuit board from delamination and failure during subsequent processing or use. Moreover, since the height difference between the outer layer board and the inner layer board at the edge region of the opening is effectively reduced by the buffer portion, the copper layer of the outer layer board will not The opening area of the film is disconnected due to the height difference, causing the line to break, thereby improving the conduction quality of the multilayer circuit board.

Description of drawings

Fig. 1 is a flow chart of the manufacturing method of the multilayer circuit board provided by the embodiment of the technical solution.

Fig. 2 is a structural schematic diagram of an inner layer board and an outer layer board used in the method of Fig. 1 .

FIG. 3 is a schematic diagram of the first structure of the film used in the method of FIG. 1 .

FIG. 4 is a schematic diagram of the second structure of the film used in the method of FIG. 1 .

Fig. 5 is a schematic diagram of thermally bonding the inner layer board and the outer layer board through the film by using the first rolling device in the method of Fig. 1 .

Fig. 6 is a top view along the I-I direction of Fig. 5 .

FIG. 7 is a schematic diagram of the method of FIG. 1 using the second rolling device to thermally bond the dry film to the outer layer.

FIG. 8 is a schematic structural view of a multilayer circuit board manufactured by the method for manufacturing a multilayer circuit board in FIG. 1 .

Fig. 9 is a top view along II-II direction of Fig. 8 .

Explanation of main component symbols

Detailed ways

The multilayer circuit board of the present technical solution and its manufacturing method will be further described in detail below in conjunction with the drawings and embodiments.

Referring to Fig. 1, the embodiment of the present technical solution provides a method for manufacturing a multilayer circuit board, which includes the following steps:

Step 110, providing an inner layer board and an outer layer board, the inner layer board includes a first insulating layer and a first conductive layer disposed on at least one surface of the first insulating layer, the outer layer board includes a second insulating layer and a first conductive layer disposed on at least one surface of the first insulating layer A second conductive layer on at least one surface of the second insulating layer.

Referring to FIG. 2 , the inner board 10 provided in this embodiment includes a first insulating layer 11 and a first conductive layer 12 . The first insulating layer 11 has a first surface 111 and a second surface 112 opposite to each other. The first surface 111 is parallel to the second surface 112 . Each of the first surface 111 and the second surface 112 is provided with a first conductive layer 12 , that is, the inner layer board 10 is a double-sided circuit board. Of course, the inner board 10 can also be a single board with only one first conductive layer 12 . In addition, a covering layer (not shown in the figure) can also be provided on the outside of the first conductive layer 12 , and the covering layer can be used to protect the first conductive layer 12 . However, the covering layer can also be omitted according to the actual requirements of different circuit boards.

The outer board 20 includes a second insulating layer 21 and a second conductive layer 22 . The second insulating layer 21 has a third surface 211 and a fourth surface 212 opposite to each other. The third surface 211 is parallel to the fourth surface 212 . In this embodiment, the second conductive layer 22 is disposed on the fourth surface 212 . Of course, the outer layer board 20 can also be provided with the second conductive layer 22 on the third surface 211, so as to constitute a double-sided circuit board.

Step 120, provide a film, the film is pre-opened with an opening area, the opening area defines two parallel and opposite design reference lines, the edge area of the opening adjacent to each design reference line on the film is formed into the opening area A plurality of uniformly and continuously arranged zigzag structures or a plurality of uniformly and continuously arranged wavy structures of the protrusions.

Please refer to FIG. 3 , the film 30 is pre-opened with an opening area 32 . The opening area 32 _defines two parallel and opposite design reference lines L ₀ , which are the original boundaries of the opening area 32 preset according to customer design requirements. The two design reference lines L ₀ are both perpendicular to the thermocompression direction P of the film.

A plurality of zigzag structures 34 are formed on the opening edge region 305 of the film 30 adjacent to each design reference line L ₀ . Each zigzag structure 34 has a first end 341 and a second end 342 opposite to each other. The first end 341 is connected to the main body 302 of the film 30 . The second end 342 extends to the opening area 32 . The connection line defining the first ends 341 of the plurality of zigzag structures 34 is a first reference line L ₁ , and the connection line defining the second ends 342 of the plurality of zigzag structures 34 is a second reference line L ₂ . The distance D 1 from the first reference line L ₁ to the _design reference line L ₀ is equal to the distance D 2 from the second reference _line L ₂ to the design reference line L ₀ . Preferably, the value range of the distance D 1 from the first reference line L ₁ to the design reference line _{L 0 and} the distance D ₂ from the second reference line L ₂ to the design reference line L ₀ is 0.5mm to between 2mm. The areas where the plurality of zigzag structures 34 are located jointly form a glue area 343 , and all areas between every two adjacent zigzag structures 34 jointly form an adhesive-free area 344 . The adhesive area 343 and the non-adhesive area 344 jointly form the opening edge area 305 . In this embodiment, the area with glue 343 is equal to the area without glue 344 . Each zigzag structure 34 has a connected first side 345 and a second side 346 . The lengths of the first side 345 and the second side 346 are equal. Preferably, the included angle between the first side 345 and the second side 346 is 60°. In this embodiment, only the case where the film 30 has one opening area 32 is shown. It can be understood that in other embodiments, the film 30 may have a plurality of opening areas 32, and the plurality of opening areas 32 may be arranged in a row on the film 30. Arranged in a column or in a matrix.

Referring to FIG. 4 , another film 40 of the present technical solution is pre-set with an opening area 42 . The opening area 42 defines two parallel and opposite design reference lines L ₁₀ , and the two design reference lines L ₁₀ are the original boundaries of the opening area 42 preset according to customer design requirements. The two design reference lines L ₁₀ are both perpendicular to the thermocompression direction P of the film. A plurality of wave-shaped structures 44 are formed on the opening edge region 405 of the film 40 adjacent to each design reference line L ₁₀ . Each corrugated structure 44 has a first end 441 and a second end 442 opposite to each other. The first end 441 is connected to the main body 402 of the film 40 . The second end 442 extends to the opening area 42 . The connecting line defining the first ends 441 of the plurality of wave-shaped structures 44 is a first reference line L ₁₁ , and the connecting line defining the second ends 442 of the plurality of wave-shaped structures 44 is a second reference line L ₁₂ . The distance D 11 from the _first reference line L ₁₁ to the design reference line L ₁₀ is equal to the distance D ₁₂ from the second reference line L ₁₂ to the design reference line L ₁₀ . Preferably, the distance D 11 from the first reference line L ₁₁ to the design reference _line L ₁₀ and the distance D ₁₂ from the second reference line L ₁₂ to the design reference line L ₁₀ are both in the range of 0.5 mm to between 2mm. The regions where the plurality of wave-shaped structures 44 are located jointly form a glue area 443 , and all areas between every two adjacent wave-shaped structures 44 jointly form a glue-free area 444 . The adhesive area 443 and the non-adhesive area 444 jointly form the opening edge area 405 . In this embodiment, the area with glue 443 is equal to the area without glue 444 . In this embodiment, only the case where the film 40 has one opening area 42 is shown. It can be understood that in other embodiments, the film 40 may have a plurality of opening areas 42 , and the plurality of opening areas 42 may be arranged in a row on the film 40. Arranged in a column or in a matrix.

In this embodiment, the film 30 or 40 is a prepreg, which softens and becomes molten after being heated.

Step 130, placing the film between the inner layer board and the outer layer board, and using a first rolling device to roll and thermally bond the inner layer board and the outer layer board in a direction perpendicular to the design reference line.

Referring to FIG. 5 , the film 30 or 40 is placed between the inner board 10 and the outer board 20 , and the inner board 10 and the outer board 20 are thermally bonded by the first rolling device 200 . In this embodiment, the use of the film 30 is taken as an example for specific description. The film 30 is heated and softened to a molten state during thermal pressing, and bonds the first conductive layer 12 of the inner board 10 and the second insulating layer 21 of the outer board 20 . When the first rolling device 200 rolls onto the opening area 32 of the film 30 , the glue in the plurality of zigzag structures 34 is heated and melted and filled in the opening edge area 305 adjacent to the corresponding design reference line L ₀ .

After thermocompression bonding, the zigzag structure 34 of the film 30 forms a buffer portion 36 on the edge region 305 of the opening. The buffer portion 36 is slope-shaped, and the buffer portion 36 has a wedge-shaped portion 362 connecting the inner board 10 and the outer board 20 . In this embodiment, the wedge portion 362 connects the first conductive layer 12 and the second insulating layer 21 .

Please refer to FIG. 6 , in this embodiment, the buffer portion 36 has a buffer boundary 364 attached to the inner board 10 , and the buffer boundary 364 is in a slightly wavy shape.

It can be understood that the corrugated structure 44 of the film 40 can also form a corresponding buffer portion on the corresponding edge area 405 of the opening. The buffer boundary where the buffer part is attached to the inner layer plate 10 is also slightly wavy.

Step 140, providing a dry film, placing the dry film on the outer side of the outer board, and thermally bonding the dry film to the outer board by using a second rolling device.

Referring to FIG. 7 , the dry film 50 is placed on the outer side of the outer board 20 , and the dry film 50 is thermally bonded to the outer board 20 by using the second rolling device 300 . Since the buffer portion 36 of the film 30 can buffer the bending degree of the outer layer board 20 at the corresponding position of the opening edge area 305 during the heat pressing process, it can avoid the outer layer board 20 from being bent excessively and causing the second conductive layer 22 to be deformed due to height difference. Too large and disconnected, causing the line to break.

Please refer to FIGS. 8-9 , this technical solution also provides a multi-layer circuit board 100 manufactured by the above manufacturing method. The multilayer circuit board 100 includes an inner board 10 , an outer board 20 , a film 30 and a dry film 50 . The film 30 is pasted between the inner board 10 and the outer board 20 . The film 30 defines an opening area 32 , and an opening edge area 305 of the opening area 32 adjacent to the film 30 has a buffer portion 36 formed by the film 30 . The dry film 50 is attached to the outer board 20 .

Specifically, the inner board 10 includes a first insulating layer 11 and a first conductive layer 12 disposed on opposite surfaces of the first insulating layer 11 . The outer board 20 includes a second insulating layer 21 and a second conductive layer 22 disposed on at least one surface of the second insulating layer 21 . The buffer portion 36 has a slope shape. The buffer portion 36 has a wedge portion 362 connecting the inner board 10 and the outer board 20 . The buffer boundary 364 where the buffer portion 36 adheres to the inner board 10 is in a slightly wavy shape. In this embodiment, the wedge portion 362 connects the first conductive layer 12 and the second insulating layer 21 .

In addition, the inner board 10 may further include a covering layer (not shown) disposed outside the first conductive layer 12 . At this time, the wedge-shaped portion 362 of the buffer portion 36 connects the covering layer and the second insulating layer 21 .

It can be understood that, when the multilayer circuit board 100 has a plurality of inner layer boards 10, the multilayer board manufacturing method provided in this embodiment can be used to thermally bond the plurality of inner layer boards 10 with the adhesive film 30 or 40 first. , and then use the film 30 or 40 to thermocompress the outer boards 20 to the opposite sides of the plurality of inner boards 10, thereby obtaining a multilayer circuit board 100 with more conductive layer structures.

Compared with the prior art, in the multi-layer circuit board and its manufacturing method of the technical solution, an opening area is opened on the film, and a zigzag structure or The wavy structure makes the zigzag structure or wavy structure of the film form a buffer in the opening area after the inner plate and the outer plate are heat-pressed, so that the gas staying in the edge area of the opening can be effectively driven away to avoid the Bubble bulges are formed at the edge of the opening, which improves the appearance quality of the multilayer circuit board and effectively prevents the multilayer circuit board from delamination and failure during subsequent processing or use. Moreover, since the height difference between the outer layer board and the inner layer board at the edge region of the opening is effectively reduced by the buffer portion, the copper layer of the outer layer board will not The opening area of the film is disconnected due to the height difference, causing the line to break, thereby improving the conduction quality of the multilayer circuit board.

It can be understood that, for those skilled in the art, various other corresponding changes and modifications can be made according to the technical concept of the technical solution, and all these changes and modifications should belong to the protection of the claims of the technical solution. scope.

Claims (12)

1. A method for making a multilayer circuit board, comprising the following steps: An inner board and an outer board are provided, the inner board includes a first insulating layer and a first conductive layer arranged on at least one surface of the first insulating layer, the outer board includes a second insulating layer and a first conductive layer arranged on the second a second conductive layer on at least one surface of the insulating layer; Provide a film, which is pre-opened with an opening area, and the opening area defines two parallel and opposite design reference lines, and the opening edge area adjacent to each design reference line on the film is formed with a protrusion protruding into the opening area. A plurality of evenly and continuously arranged zigzag structures or a plurality of evenly and continuously arranged wavy structures; placing the film between the inner panel and the outer panel, and using a first rolling device to roll and thermally bond the inner panel and the outer panel in a direction perpendicular to the design reference line; and providing a dry film, placing the dry film on the outer side of the outer layer board, and thermally bonding the dry film to the outer layer board by using a second rolling device. 2. The method for manufacturing a multilayer circuit board according to claim 1, wherein each zigzag structure or each wavy structure has a first end and a second end opposite to each other, and the first end is in contact with the film The main body is connected, and the second end extends to the opening area. 3. The method for manufacturing a multilayer circuit board as claimed in claim 2, wherein the lines defining the first ends of the plurality of zigzag structures or the plurality of wavy structures are first reference lines, and defining the plurality of wavy structures The line connecting the second ends of the zigzag structures or multiple wavy structures is the second reference line, and the distance from the first reference line to the design reference line is equal to the distance from the second reference line to the design reference line. 4. The manufacturing method of multilayer circuit board as claimed in claim 3, characterized in that, the distance from the first reference line to the design reference line and the value of the distance from the second reference line to the design reference line The ranges are all between 0.5mm and 2mm. 5. The method for manufacturing a multilayer circuit board according to claim 1, wherein the plurality of zigzag structures or the regions where the plurality of wavy structures are located jointly form a glue zone, and each adjacent two zigzag structures Or all the areas between the wave-shaped structures jointly form a glue-free zone, and the area of the glue-filled zone is equal to the area of the glue-free zone. 6 . The method for manufacturing a multilayer circuit board as claimed in claim 1 , wherein each zigzag structure has a first side and a second side connected thereto, and the lengths of the first side and the second side are equal. 7 . 7. The method for manufacturing a multilayer circuit board as claimed in claim 6, wherein the angle between the first side and the second side is 60°. 8. The method of manufacturing a multilayer circuit board according to claim 1, wherein the film is placed between the inner layer board and the outer layer board and the inner layer is thermally bonded by a first rolling device After the plate and the outer plate, the zigzag structures or wave structures of the film form buffers on the edge area of the opening. 9 . The manufacturing method of a multilayer circuit board as claimed in claim 8 , wherein the buffer portion is slope-shaped, and the buffer portion has a wedge-shaped portion connecting the inner layer board and the outer layer board. 10 . 10 . The manufacturing method of a multi-layer circuit board according to claim 8 , wherein the buffer portion has a buffer boundary adhering to the inner layer board, and the buffer boundary is in a wave shape. 11 . 11. A multilayer circuit board, comprising an inner layer board, an outer layer board, a film and a dry film, the film is attached between the inner layer board and the outer layer board, the film is provided with an opening area, and the opening area The edge area of the opening adjacent to the film has a buffer portion formed by the film, the buffer portion has a buffer boundary attached to the inner plate, the buffer boundary is in a micro wave shape, and the dry film is attached to the outer layer plate. 12 . The multilayer circuit board as claimed in claim 11 , wherein the buffer portion is slope-shaped, and the buffer portion has a wedge-shaped portion connecting the inner layer board and the outer layer board. 13 .

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