Disclosure of Invention
The invention provides an electromagnetic interference shielding structure, a flexible circuit board with the electromagnetic interference shielding structure and a manufacturing method thereof.
The electromagnetic interference shielding structure comprises an adhesion layer, an insulating layer and a metal shielding layer. The opposite sides of the insulating layer directly contact the adhesion layer and the metal shielding layer.
In an embodiment of the invention, the emi shielding structure further includes a protective layer. The protective layer covers the metal shielding layer and is opposite to the insulating layer.
In an embodiment of the invention, the metal shielding layer includes a first metal layer and a second metal layer. The insulating layer directly contacts the first metal layer. The first metal layer is a film layer composed of metal.
The flexible circuit board with the electromagnetic interference shielding structure comprises a flexible circuit board body and the electromagnetic interference shielding structure. The electromagnetic interference shielding structure is configured on the flexible circuit board body. The bonding layer of the electromagnetic interference shielding structure directly contacts the flexible circuit board body.
In an embodiment of the invention, the flexible circuit board with the emi shielding structure further includes a conductive via. The conductive via penetrates the electromagnetic interference shielding structure. The flexible circuit board body comprises a flexible substrate and a circuit layer. The conductive through hole is electrically connected with the metal shielding layer and part of the circuit layer.
In an embodiment of the invention, the sidewall of the conductive via is substantially perpendicular to the flexible circuit board body.
In an embodiment of the present invention, a top surface of the conductive via is substantially flush with a top surface of the EMI shielding structure.
In an embodiment of the invention, the flexible circuit board body further includes a conductive layer, and the flexible substrate is located between the circuit layer and the conductive layer.
The manufacturing method of the flexible circuit board with the electromagnetic interference shielding structure comprises the following steps. A flexible printed circuit board is provided. The electromagnetic interference shielding structure is jointed with the flexible circuit board body, and the adhesion layer of the electromagnetic interference shielding structure is directly contacted with the flexible circuit board body.
In an embodiment of the invention, the flexible circuit board body includes a flexible substrate and a circuit layer. The manufacturing method of the flexible circuit board with the electromagnetic interference shielding structure further comprises the following steps. And at least carrying out laser burning on the electromagnetic interference shielding structure to form a conductive through hole penetrating through the electromagnetic interference shielding structure, wherein the conductive through hole is electrically connected with the metal shielding layer and part of the circuit layer.
Based on the above, the overall thickness of the flexible circuit board with the electromagnetic interference shielding structure of the invention can be thinner, and the material cost can be lower.
In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.
Detailed Description
The foregoing and other technical and scientific aspects, features and utilities of the present invention will be apparent from the following detailed description of various embodiments, which is to be read in connection with the accompanying drawings. Directional terms as referred to in the following examples, for example: "upper", "lower", "front", "rear", "left", "right", etc., refer only to the orientation of the figures. Accordingly, the directional terminology is used for purposes of illustration and is in no way limiting. Also, in the following embodiments, the same or similar elements will be given the same or similar reference numerals.
Fig. 1A to fig. 1E are schematic partial cross-sectional views illustrating a method for manufacturing a flexible circuit board 100 having an emi shielding structure according to a first embodiment of the invention.
Referring to fig. 1A, a flexible circuit board body 110 is provided. The flexible circuit board body 110 may include a flexible substrate 112 and a circuit layer 111. In the present embodiment, the flexible circuit board body 110 is, for example, a single-sided flexible printed circuit board (which may be referred to as a single-sided board), but the invention is not limited thereto. That is, in the embodiment, the flexible circuit board body 110 is not a multi-layer printed circuit board (PCB, which may be simply referred to as a multi-layer board).
It is noted that, in fig. 1A, only a portion of the circuit layer 111 is exemplarily shown. The routing (layout) in the routing layer 111 can be adjusted according to design requirements, and is not limited in the present invention. In other words, in another cross section not shown, only a portion of the circuit layer 111 may be covered on the flexible substrate 112; in another cross section not shown, the circuit layer 111 may not be formed on the flexible substrate 112.
Referring to fig. 1B to fig. 1C, the emi shielding structure 500 is bonded to the flexible circuit board body 110.
The emi shielding structure 500 includes a bonding layer 510, an insulating layer 520, and a metal shielding layer 530. The insulating layer 520 has a first insulating surface 520a and a second insulating surface 520b opposite to each other. The first insulating surface 520a of the insulating layer 520 directly contacts the adhesive layer 510. The second insulating surface 520b of the insulating layer 520 directly contacts the metal shielding layer 530.
In this embodiment, the emi shielding structure 500 may further include a protective layer 540. The protective layer 540 covers the metal shielding layer 530. The protective layer 540 is opposite to the insulating layer 520. In other words, the metal shielding layer 530 is located between the protection layer 540 and the insulating layer 520. The protection layer 540 may be an insulating material having a hardness greater than that of metal, but the invention is not limited thereto. The protective layer 540 may reduce the possibility of damage and/or oxidation of the metal shielding layer 530.
In this embodiment, the metal shielding layer 530 may include a first metal layer 531 and a second metal layer 532. The second insulating surface 520b of the insulating layer 520 directly contacts the first metal layer 531, and the first metal layer 531 is a film layer composed of metal. In other words, the first metal layer 531 may not be a film layer formed of a conductive adhesive. The conductive adhesive is, for example, a composite material (e.g., silver paste, aluminum paste) comprising a binder (e.g., resin) and a conductive material (e.g., metal powder). That is, since the emi shielding structure 500 does not have the conductive adhesive, the thickness thereof can be thin and the material cost can be low.
In an embodiment, a bonding force between the first metal layer 531 and the insulating layer 520 is greater than a bonding force between the second metal layer 532 and the insulating layer 520, and an electrical conductivity (electrical conductivity) of the second metal layer 532 is greater than that of the first metal layer 531. For example, the insulating layer 520 is made of Polyimide (PI), the first metal layer 531 is made of nickel, and the second metal layer 532 is made of copper, but the invention is not limited thereto.
In an embodiment, the thickness 532t of the second metal layer 532 may be greater than the thickness 531t of the first metal layer 531. The thickness 532t of the second metal layer 532 may be 10 times to 50 times the thickness 531t of the first metal layer 531, but the present invention is not limited thereto.
In one embodiment, the first metal layer 531 may be referred to as a metal adhesive layer (metallic adhesive layer), but the invention is not limited thereto.
In one embodiment, the material of the adhesion layer 510 may comprise a curable material. For example, in fig. 1B, the material in the adhesion layer 510 may be in a semi-cured or uncured state. After the semi-cured or uncured material is contacted with the flexible circuit board body 110, a curing step (e.g., photo-curing, thermal-curing and/or static curing) may be performed according to the material in the adhesive layer 510, so that the emi shielding structure 500 and the flexible circuit board body 110 are tightly combined as shown in fig. 1C.
Referring to fig. 1C to fig. 1D, in an embodiment, after the electromagnetic interference shielding structure 500 is combined with the flexible circuit board body 110, an opening 551 exposing the circuit layer 111 may be formed on the electromagnetic interference shielding structure 500.
In one embodiment, the opening 551 may be formed by laser ablation by the laser device 60. Compared with the opening formed by wet etching, the opening 551 formed by the laser device 60 is less prone to lateral etching, and therefore undercut (undercut) is reduced. That is, the sidewall 551c of the opening 551 can be substantially perpendicular to the surface of the flexible circuit board body 110 (e.g., perpendicular to the surface of the flexible substrate 112 of the flexible circuit board body 110).
In addition, the opening 551 can be formed directly through the laser device 60 according to design requirements. That is, the laser device 60 does not need to form the opening 551 using a photomask. Therefore, the design of the position of the opening 551 has better changeability, and can be adjusted quickly according to the design requirement.
Referring to fig. 1D to fig. 1E, in an embodiment, after forming the opening 551, a conductive material may be filled in the opening 551 to form a conductive via 552. The conductive material may be silver paste, aluminum paste, solder paste, other suitable conductive paste or conductive paste. The conductive via 552 electrically connects the metal shielding layer 530 of the emi shielding structure 500 and the portion of the circuit layer 111 exposed by the opening 551.
In one embodiment, the shape of the conductive via 552 substantially corresponds to the profile of the opening 551. In other words, the sidewall 552c of the conductive via 552 can be substantially perpendicular to the surface of the flexible circuit board body 110 (e.g., perpendicular to the surface of the flexible substrate 112 of the flexible circuit board body 110).
In an embodiment, a top surface 552a of the conductive via 552 may be substantially flush with a top surface 500a of the emi shielding structure 500.
The manufacturing of the flexible circuit board 100 with the emi shielding structure of the present embodiment can be substantially completed through the above processes. The flexible circuit board 100 with the emi shielding structure includes a flexible circuit board body 110 and an emi shielding structure 500. The emi shielding structure 500 is disposed on the flexible circuit board body 110. The emi shielding structure 500 includes a bonding layer 510, an insulating layer 520, and a metal shielding layer 530. The first insulating surface 520a of the insulating layer 520 directly contacts the adhesive layer 510. The second insulating surface 520b of the insulating layer 520 directly contacts the metal shielding layer 530. The adhesion layer 510 of the emi shielding structure 500 directly contacts the flexible circuit board body 110.
In this embodiment, the flexible circuit board 100 with the emi shielding structure may further include a conductive via 552. A conductive via 552 extends through emi shielding structure 500. The conductive vias 552 are electrically connected to the metal shielding layer 530 and a portion of the circuit layer 111 of the flexible circuit board body 110.
In an embodiment, a portion of the circuit layer 111 electrically connected to the conductive via 552 may be grounded, but the invention is not limited thereto.
Fig. 2 is a schematic partial cross-sectional view of a flexible circuit board 200 having an emi shielding structure according to a second embodiment of the invention.
In the present embodiment, the manufacturing method of the flexible circuit board 200 with the emi shielding structure is similar to the manufacturing method of the flexible circuit board 100 with the emi shielding structure of the first embodiment, and similar components are denoted by the same reference numerals and have similar functions, materials or forming manners, and descriptions thereof are omitted.
The flexible printed circuit 200 with emi shielding structure includes a flexible printed circuit body 210 and an emi shielding structure 500. The flexible circuit board body 210 may include a flexible substrate 112, a circuit layer 111 and a conductive layer 213. The flexible substrate 112 is located between the circuit layer 111 and the conductive layer 213.
In one embodiment, the conductive layer 213 is a film layer made of metal. For example, the material of the conductive layer 213 is copper, but the invention is not limited thereto.
In an embodiment, the conductive layer 213 may be a full-surface film, but the invention is not limited thereto. In another embodiment, the conductive layer 213 may have a corresponding pattern, and the pattern of the conductive layer 213 may be adjusted according to design requirements. In other words, in another cross section not shown, only a portion of the conductive layer 213 may cover the flexible substrate 112; in another cross section not shown, the conductive layer 213 may not be present on the flexible substrate 112.
In the present embodiment, the flexible circuit board body 210 is, for example, a double-sided flexible printed circuit board (double-sided flexible printed circuit board). That is, in the embodiment, the flexible circuit board body 210 is not a multi-layer printed circuit board (PCB, which may be simply referred to as a multi-layer board).
In an embodiment, at least a portion of the conductive layer 213 may be grounded. In other words, the conductive layer 213 may serve as an electromagnetic interference shield, but the present invention is not limited thereto.
In summary, the thickness of the emi shielding structure of the present invention can be thinner, and the material cost can be lower. In addition, the flexible circuit board with the electromagnetic interference shielding structure can be thinner in overall thickness and lower in material cost.
Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.