TWI693004B - Rigid-flex circuit board and method for making the same - Google Patents

Abstract

The present invention relates to a rigid-flex circuit board. The rigid-flex circuit board includes a flexible core substrate, a cover layer, a dielectric layer, and an outer conductive circuit layer. The flexible core substrate includes a flexible substrate and two inner conductive circuit layers which formed on two opposite surfaces of the flexible substrate. The cover layer is formed on the surface of the inner conductive circuit layer. The cover layer includes several windows. Part of the inner conductive circuit layer is exposed from the windows. The dielectric layer is formed on the part of the surface of the cover layer and filled the windows. The outer conductive circuit layer is formed on the dielectric layer. The rigid-flex circuit board also includes several conductive holes. The conductive holes is formed in the outer conductive circuit layer and through dielectric layer in the windows to electrically connect the inner conductive circuit layer. The diameter of the conductive hole is less than the diameter of the window.

Description

Soft and hard combined board and manufacturing method thereof

The invention relates to the technical field of circuit boards, in particular to a soft and hard composite board and a manufacturing method thereof.

The soft and hard board is the flexible circuit board and the rigid circuit board, which are combined together according to the relevant process requirements through the pressing and other processes to form a circuit board with FPC characteristics and PCB characteristics. The main types of products used in the combination of soft and hard boards are: mobile phones, key boards and side buttons, computer and LCD screen motherboards and display screens, CD Walkman and other products.

However, in the prior art, in order to realize the electrical conduction between the inner layer conductive circuit and the outer layer conductive circuit in the soft and hard bonding board, a blind hole is generally opened, and then the blind hole is plated with copper. However, the flexible circuit board includes a cover film, which is hard The circuit board generally includes epoxy resin, so that in the process of blind hole opening, the laser beam needs to be applied to different resin systems. Because the energy of the laser beam absorbed by different resin systems is different, the hole type of the blind hole It is difficult to control; after the blind hole is opened, the residual resin glue in the blind hole needs to be removed to perform the electroplating step, but due to the different resin systems, the rate of slag wiping will also be different, and the removal of the slag will not affect the plating quality If excessive slag is removed, blind holes will be easily scrapped.

In view of this, it is necessary to provide a soft-hard joint board, a pressure-sensitive circuit board and a method for manufacturing the pressure-sensitive circuit board that can solve the above technical problems.

A soft and hard combined board, comprising: a flexible board core board, the flexible board core board comprises a flexible board base material and inner conductive circuit layers respectively located on two surfaces opposite to the flexible board base material;

A cover film formed on the surface of the conductive circuit layer, the cover film including a window opening, the window opening revealing a part of the surface of the inner conductive circuit layer;

A dielectric layer formed on a part of the surface of the cover film and filling the window opening;

An outer conductive circuit layer, the outer conductive circuit layer is formed on the dielectric layer, the soft and hard bonding board further includes a conductive hole, the conductive hole is opened from the outer conductive circuit layer and penetrates the opening The dielectric layer is electrically connected to the inner conductive circuit layer, and the diameter of the conductive hole is smaller than that of the window.

Further, the dielectric layer includes a prepreg formed on the surface of the cover film, a substrate layer is further formed between the dielectric layer and the outer conductive circuit layer, the prepreg fills the window, the substrate The material layer is the same as the material of the prepreg.

Further, the portion where the dielectric layer is formed on the surface of the cover film is the hard board portion of the soft-hard joint board, and the portion not covered by the dielectric layer is the soft board portion of the soft-hard joint board, the soft A gold finger is formed on the surface of the inner conductive layer on one surface of the board portion away from the hard board portion, and the cover film exposes the gold finger.

Further, a reinforcing layer is formed on one surface of the flexible board portion and the cover film, and an electromagnetic shield layer is formed on the surface of the other cover film.

Further, the outer conductive circuit layer includes a conductive pad, the conductive pad surrounds the conductive hole and connects to the circumferential sidewall of the conductive hole, a solder resist layer is formed on the surface of the outer conductive circuit layer, and the solder resist layer A top surface of the conductive pad and the conductive hole is exposed, and a surface treatment layer is formed on the common surface of the conductive pad and the conductive hole.

A method for manufacturing a soft and hard board includes:

Provide a flexible board core board, the flexible board core board includes a flexible board base material and inner conductive circuit layers respectively located on two surfaces opposite to the flexible board base material;

A cover film is provided, the cover film includes a window, the cover film is pressed and formed on the surface of the inner conductive circuit layer, and the window exposes a part of the surface of the inner conductive circuit layer;

Forming a dielectric layer on a part of the surface of the cover film and filling the window with the dielectric layer;

Providing a hard board, the hard board including a copper foil layer, and pressing the hard board to the dielectric layer;

A laser is used to form a blind hole penetrating the copper foil layer and the dielectric layer in the window from the copper foil layer, and the blind hole has a smaller aperture than the window, and the blind hole Exposing part of the inner conductive circuit layer;

Forming the blind hole as a conductive hole; and

The copper foil layer is formed as an outer conductive circuit layer, and the conductive holes are electrically connected to the outer conductive circuit layer and the inner conductive circuit layer.

Further, the dielectric layer includes a prepreg, and the rigid board provided includes a base material layer and the copper foil layer formed on the surface of the base material layer, the base material layer and the prepreg material are the same; Before the hard plate is pressed against the surface of the cover film, it further includes forming a prepreg on the surface of the cover film, and filling the window with the prepreg.

Further, the portion where the dielectric layer is formed on the surface of the cover film is the hard board portion of the soft and hard bonded board, and the portion of the soft board core board provided that is not covered by the dielectric layer is the soft and hard bonded board The flexible board portion has a gold finger formed on the surface of the inner conductive layer on one surface of the flexible board portion away from the hard board portion, and the cover film exposes the gold finger.

Further, a reinforcing layer is formed on one surface of the flexible board portion and the cover film, and an electromagnetic shield layer is formed on the surface of the other cover film.

Further, the outer conductive circuit layer formed includes a conductive pad, the conductive pad surrounds the conductive hole and connects to the circumferential side wall of the conductive hole, and after the outer conductive circuit layer is formed, the conductive layer further includes conductive on the outer layer A solder resist layer is formed on the surface of the circuit layer, the solder resist layer exposes the top ends of the conductive pads and the conductive holes, and after the solder resist layer is formed, a surface treatment is also formed on the common surface of the conductive pads and the conductive holes Floor.

Compared with the prior art, the manufacturing method of the soft and hard bonding board provided by the present invention only needs to process the same resin system to form the soft and hard bonding board, and the single resin system is stable to the absorption energy of the laser beam , The shape of the blind hole can be guaranteed; after the blind hole is processed, it is necessary to remove the slag from the blind hole before electroplating it to form a conductive hole. Because the residual resin in the blind hole is the same resin system, the normal glue can be used The slag erasure parameter operation can ensure the quality of the slag erasure, and will not cause the incomplete erasure of the scum erasure or the excessive slag erasure.

In the following, in conjunction with the accompanying drawings and embodiments, the soft and hard coupling board and the manufacturing method thereof provided by the present invention will be further described in detail.

The invention relates to a method for manufacturing a soft-hard joint board, which includes the following steps:

Step 1: Please refer to FIG. 1 to provide a flexible board core board 10, the flexible board core board 10 includes a flexible board base material 13 and first inner conductive circuit layers respectively located on two surfaces opposite to the flexible board base material 13 11和第一内层 inch. The conductive line layer 12. The material of the flexible board substrate 13 may be a material such as polyimide (PI) or polyethylene biphthalate (Poly Ethylene Terephthalate PET). The first inner conductive circuit layer 11 and the second inner conductive circuit layer 12 communicate with each other through the first conductive hole 101. The formation of the first inner layer conductive circuit layer 11 and the second inner layer conductive circuit layer 12 includes the steps of: sticking a dry film→exposure→development→etching→removing the film. Since the manufacturing process of the flexible board core board 10 is a conventional process of those skilled in the art, the specific operation process will not be described in detail here.

Step 2: Please refer to FIG. 1 and FIG. 2, a cover film 20 is provided. The cover film 20 includes a window 201. The cover film includes a film layer 21 and an adhesive layer 22. The cover film 20 is pressed and formed on the surface of the first inner conductive circuit layer 11 or/and the second inner conductive circuit layer 12 and cured to obtain the first laminated structure 30. The glue layer 22 also fills the first conductive hole 101. In this embodiment, the cover film 20 is pressed onto the surfaces of the first inner-layer conductive wiring layer 11 and the second inner-layer conductive wiring layer 12, respectively. The window 201 exposes part of the surfaces of the first inner conductive circuit layer 11 and the second inner conductive circuit layer 12. The window 201 is formed by punching, cutting, lasering, etc. with a die. After forming the first inner layer conductive circuit layer 11 and the second inner layer conductive circuit layer 12, a gold finger 14 is formed on the surface of the second inner layer conductive circuit layer 12 near the edge of the flexible board core board 10. The cover film 20 also exposes the golden finger 14.

Step 3: Please refer to FIG. 3, the first laminated structure 30 is divided into a first area 32 and a second area 34, the window 201 is located in the first area 32, and the gold finger 14 is located in the second Region 34. Here, the first area 32 is used to form a hard plate portion in a subsequent step, and the second area 34 is used to form a soft plate portion.

Step 4: Please refer to FIG. 4, a dielectric layer 40 is formed on the first region 32 and part of the surface of the cover film 20 and fills the window 201 with the dielectric layer 40; in the present invention, the dielectric layer The material of 40 is prepreg PP.

Step 5: Please refer to FIG. 5 to provide a hard board 50. In this embodiment, the hard board 50 is a single-sided copper-clad substrate, which includes a base layer 51 and copper formed on the surface of the base layer 51 For the foil layer 52, the material of the base layer 51 is epoxy glass fiber board (FR4).

Pressing the hard board 50 to the dielectric layer 40 obtains the second laminated structure 60. In this embodiment, the hard plates 50 are pressed onto the surfaces of the two dielectric layers 40 respectively. Therefore, the first region 32 is formed as the hard plate portion 61, and the portion not covered by the dielectric layer 40 and the hard plate 50 is the soft plate portion 63.

In other embodiments, the hard board 50 may be only copper foil.

Step 6: Please refer to FIG. 6, a laser is used to form the dielectric layer 40 penetrating through the copper foil layer 51, the base material layer 52 and the window 201 from the surface of the copper foil layer 51的眼孔601. The hole diameter of the blind hole 601 is smaller than the hole diameter of the window 201, and a portion of the first inner conductive circuit layer 11 is exposed at the bottom of the blind hole 601.

Here, the aperture of the blind hole 601 is smaller than the aperture of the window 201, so that when the laser beam is used to form the blind hole 601, the laser beam passes through the substrate layer 51 and the medium Layer 40, the material of the base material layer 51 is FR4, the medium layer 40 is a prepreg, the base material layer 51 and the medium layer 40 are both epoxy resin systems, so the laser beam is processed by a single resin System, the absorption energy of the laser beam by a single resin system is stable, and the shape of the blind hole 601 can be guaranteed; in other embodiments, if the hard plate 50 includes only the copper foil layer, the laser beam only passes through the dielectric layer 40; After the blind hole 601 is processed, the glue slag needs to be removed from the blind hole 601 before electroplating. Since the residue in the blind hole 601 is mainly the same resin system, it can be operated according to the normal glue slag removal parameters, which can guarantee The quality of the rubber slag erasure will not lead to incomplete erasing of the plastic slag or excessive erasure of the plastic slag.

Step 7: Referring to FIG. 7, the blind hole 601 is formed as a second conductive hole 603. In the cross-sectional view of this embodiment, four second conductive holes 603 are shown, which are respectively located on the upper and lower surfaces of the flexible board core board 10, and the distance between two adjacent second conductive holes 603 on the same side (Pitch) needs to satisfy the sum of the dimension D greater than or equal to the window 201 and the minimum distance Dc between two adjacent windows.

Step 8: Referring to FIG. 8, the copper foil layers 52 included in the two rigid boards 50 are respectively formed as outer conductive circuit layers 521. The second conductive holes 603 are used to electrically connect one of the outer conductive circuit layer 521 and the first inner conductive circuit layer 11; and to connect the other outer conductive circuit layer 521 and the second inner layer Conductive circuit layer 12. The formed outer conductive circuit layer 521 includes a conductive pad 531 that surrounds the second conductive hole 603 and is electrically connected to the side wall of the second conductive hole 603.

Step 9: Please refer to FIG. 9, a solder resist layer 70 is formed on the surface of the outer conductive circuit layer 521 respectively, the solder resist layer 70 exposes the tops of the conductive pad 531 and the second conductive holes 603, so A surface treatment layer 72 is formed on the top surfaces of the conductive pad 531 and the second conductive hole 603. In this embodiment, it further includes forming the reinforcing layer 301 and the electromagnetic shielding layer 303 on the two opposite surfaces of the cover film 20 of the flexible board portion 63. Wherein, the electromagnetic shielding layer 303 and the golden finger 14 are located on the same side of the first laminated structure 30, and the electromagnetic shielding layer 303 is used to prevent electromagnetic interference. The reinforcing layer 301 includes an adhesive layer 311 and a PI (Polyimide, Polyimide) reinforcing sheet 313. The reinforcing layer is used to protect the second region 34. In this way, the soft and hard bonding board 100 is obtained.

Please refer to FIG. 9 again. The present invention also relates to a soft-hard joint board 100 formed by using the above-mentioned soft-hard joint board manufacturing method.

The rigid-flex board 100 includes a flexible core board 10, a cover film 20 formed on the surface of the flexible core board 10, a dielectric layer 40 formed on part of the surface of the cover film 20, and a dielectric layer formed on the dielectric layer The base material layer 51 on the surface 40 and the outer conductive layer 521 formed on the surface of the base material layer 51.

Specifically, the flexible board core board 10 includes a flexible board substrate 13 and the first inner layer conductive circuit layer 11 and the second inner layer conductive circuit layer 12 located on two opposite surfaces of the flexible board substrate 13; The first inner conductive circuit layer 11 and the second inner conductive circuit layer 12 communicate with each other through the first conductive hole 101. The material of the flexible board substrate 13 may be a material such as polyimide or Polyethyleneterephthalate PET.

The cover film 20 at one end of the flexible board core 10 and its surface is formed as a flexible board portion 63. The other end of the flexible core board 10, the dielectric layer 40 formed on the surface of the flexible core board 10, the base material layer 51 formed on the surface of the dielectric layer 40, and the outer conductive circuit layer 521 together form the hard plate portion 61.

The cover film includes a film layer 21 and an adhesive layer 22. The cover film 20 is formed on the surfaces of the first inner conductive circuit layer 11 and the second inner conductive circuit layer 12, respectively. The glue layer 22 also fills the first conductive hole 101. The cover film 20 includes a window 201 that exposes a part of the surface of the first inner conductive circuit layer 11 and the second inner conductive circuit layer 12. The cover film 20 also fills the first conductive hole 101. The cover film 20 includes an adhesive layer and a cover layer.

The dielectric layer 40 is formed on a part of the surface of the cover film 20 and fills the window 201. The material of the dielectric layer 40 is a prepreg.

The base material layer 51 is formed on the surface of the dielectric layer 40. The material of the base layer 51 is FR4. That is, neither the base material layer 51 nor the dielectric layer 40 is made of epoxy resin.

The outer conductive layer 521 is formed on the surface of the base layer 51. The outer conductive circuit layer 521 communicates with the first inner conductive circuit layer 11 or the second inner conductive circuit layer 12 through the second conductive hole 603. The second conductive hole 603 penetrates the outer conductive circuit layer 521, the base material layer 51 and the dielectric layer 40 in the window 201 until it is electrically connected to the first inner conductive circuit layer 11 Or the second inner conductive line layer 12. The window 201 exposes part of the surfaces of the first inner conductive circuit layer 11 and the second inner conductive circuit layer 12. The diameter of the second conductive hole 603 is smaller than the diameter of the window 201.

The outer conductive circuit layer 521 includes a conductive pad 531 that surrounds the second conductive hole 603 and connects to the circumferential side wall of the second conductive hole 603.

A solder resist layer 70 is formed on the surface of the outer conductive circuit layer 521, the solder resist layer 70 exposes the top ends of the conductive pad 531 and the second conductive hole 603, the conductive pad 531 and the second conductive A surface treatment layer 72 is formed on the surface common to the holes 603.

In summary, the present invention meets the requirements of the invention patent, and the patent application is filed in accordance with the law. However, the above are only preferred embodiments of the present invention. For those who are familiar with the skills of this case, equivalent modifications or changes made in accordance with the spirit of the present invention should be covered within the scope of the following patent applications.

100‧‧‧Soft and hard board 10‧‧‧Soft core board 13‧‧‧ soft substrate 11‧‧‧ First inner conductive layer 12‧‧‧Second inner conductive circuit layer 14‧‧‧Goldfinger 101‧‧‧The first conductive hole 20‧‧‧covering film 21‧‧‧film 22‧‧‧adhesive layer 201‧‧‧Open window 30‧‧‧The first laminated structure 32‧‧‧The first area 34‧‧‧Second area 301‧‧‧ Reinforcement 303‧‧‧Electromagnetic mask layer 311‧‧‧adhesive layer 313‧‧‧Reinforcement 40‧‧‧medium layer 50‧‧‧hard board 51‧‧‧Copper foil layer 52‧‧‧Base layer 521‧‧‧ Outer conductive circuit layer 60‧‧‧Second laminated structure 61‧‧‧Hard Board Department 63‧‧‧Soft Board Department 601‧‧‧blind hole 603‧‧‧Second conductive hole 531‧‧‧Conductive pad 70‧‧‧Soldering layer 72‧‧‧Surface treatment layer

FIG. 1 is a cross-sectional view of a flexible board core board and a cover film provided by the present invention.

FIG. 2 is a cross-sectional view of the first laminated structure formed by pressing together the flexible board core board and the cover film provided in FIG. 1.

3 is a cross-sectional view of forming a gold finger on the surface of the second inner conductive layer.

4 is a cross-sectional view of pressing the dielectric layer on the basis of FIG. 3 and filling the window with the dielectric layer.

FIG. 5 is a cross-sectional view of a second laminated structure formed by pressing a hard plate on the basis of FIG. 4.

6 is a cross-sectional view of forming a blind hole in a second stacked structure.

7 is a cross-sectional view of forming a blind hole into a conductive hole.

FIG. 8 is a cross-sectional view of a copper foil layer included in a hard board as an outer conductive layer.

FIG. 9 is a cross-sectional view of a soft and hard bonding board by performing a solder mask treatment on the surface of the outer conductive circuit layer and forming a reinforcing layer or an electromagnetic shielding layer on the flexible board portion.

no

100‧‧‧Soft and hard board

13‧‧‧ soft substrate

11‧‧‧ First inner conductive layer

12‧‧‧Second inner conductive circuit layer

14‧‧‧Goldfinger

101‧‧‧The first conductive hole

20‧‧‧covering film

21‧‧‧film

22‧‧‧adhesive layer

201‧‧‧Open window

301‧‧‧ Reinforcement

303‧‧‧Electromagnetic mask layer

40‧‧‧medium layer

51‧‧‧Copper foil layer

521‧‧‧ Outer conductive circuit layer

61‧‧‧Hard Board Department

63‧‧‧Soft Board Department

603‧‧‧Second conductive hole

531‧‧‧Conductive pad

70‧‧‧Soldering layer

72‧‧‧Surface treatment layer

Claims (10)

A soft-rigid combination board, comprising: a flexible board core board, the flexible board core board comprises a flexible board base material and inner conductive circuit layers respectively located on two surfaces opposite to the flexible board base material; a cover film is formed on the On the surface of the inner conductive circuit layer, the cover film includes a window that exposes a part of the surface of the inner conductive circuit layer; a dielectric layer, the dielectric layer is formed on a part of the surface of the cover film And fill the window; a hard board, the hard board is formed on the dielectric layer, the hard board includes an outer conductive circuit layer, the improvement is that the soft and hard bonding board also includes conductive holes, so The conductive hole is opened from the outer conductive circuit layer and penetrates through the dielectric layer in the window to electrically connect the inner conductive circuit layer. The diameter of the conductive hole is smaller than that of the window. The soft and hard bonding board as described in item 1 of the patent application range, wherein the dielectric layer includes a prepreg formed on the surface of the cover film, and the prepreg fills the window. The soft and hard bonding board as described in item 2 of the patent application range, wherein the portion of the cover film on which the dielectric layer is formed is the hard board portion of the soft and hard bonding board, and the portion not covered by the dielectric layer is the A soft board portion of the rigid-flex board, an inner conductive circuit layer on one surface of the soft board portion has a gold finger formed on a surface of an end away from the hard board portion, and the cover film exposes the gold finger; A reinforcing layer or an electromagnetic shielding layer is formed on the surface of the cover film of the flexible board portion. The soft and hard bonding board as described in item 3 of the patent application scope, wherein the hard board is a single-sided copper-clad substrate or pure copper foil; if the hard board is a single-sided copper-clad substrate, the hard board includes The material of the substrate layer is the same as the material of the prepreg. The soft and hard bonding board as described in item 1 of the patent application scope, wherein the outer conductive circuit layer includes a conductive pad, the conductive pad surrounds the conductive hole and connects to the side wall of the conductive hole, and the outer conductive circuit layer A solder resist layer is formed on the surface, and the solder resist layer exposes the top ends of the conductive pads and the conductive holes, and a surface treatment layer is formed on the top surfaces of the conductive pads and the conductive holes. A method for manufacturing a flexible rigid board, comprising: providing a flexible board core board, the flexible board core board including a flexible board base material and inner conductive circuit layers respectively located on two surfaces opposite to the flexible board base material; providing coverage Film, the cover film includes a window opening, the cover film is pressed and formed on the surface of the inner conductive circuit layer, the window opening exposes a part of the surface of the inner conductive circuit layer; Forming a dielectric layer on a part of the surface of the film and filling the window with the dielectric layer; providing a hard plate including the copper foil layer, pressing the hard plate to the dielectric layer; from the copper foil layer Forming a blind hole penetrating the copper foil layer and the dielectric layer in the window, the hole diameter of the blind hole is smaller than the hole diameter of the window, the blind hole reveals part of the inner conductive circuit layer Forming the blind hole as a conductive hole; and forming the copper foil layer as an outer conductive circuit layer, the conductive hole electrically connecting the outer conductive circuit layer and the inner conductive circuit layer. The method for manufacturing a soft and hard bonding board as described in item 6 of the patent application scope, wherein the dielectric layer includes a prepreg, and the provided hard board includes a base material layer and the copper foil formed on the surface of the base material layer Layer, the base material layer is the same material as the prepreg; before pressing the hard plate onto the surface of the cover film, it further includes pressing the prepreg on the surface of the cover film, and filling the prepreg Describe the window. The method for manufacturing a soft and hard bonding board as described in item 7 of the patent application range, wherein the portion where the dielectric layer is formed on the surface of the cover film is the hard board portion of the soft and hard bonding board, and the soft board core board is provided A portion of one end that is not covered by the dielectric layer is a soft board portion of the soft-hard board, and an inner conductive circuit layer on one surface of the soft board portion is formed with gold on the surface of the end away from the hard board portion For fingers, the cover film reveals the golden fingers. The method for manufacturing a rigid-flexible board as described in item 8 of the patent application scope, wherein the surface of the flexible board portion and the cover film is formed with a reinforcement layer or an electromagnetic shielding layer. The manufacturing method of the soft and hard bonding board as described in item 9 of the patent application scope, wherein the outer conductive circuit layer formed includes a conductive pad, the conductive pad surrounds the conductive hole and connects to the side wall of the conductive hole, After forming the outer conductive circuit layer, the method further includes forming a solder resist layer on the surface of the outer conductive circuit layer, the solder resist layer reveals the tops of the conductive pads and the conductive holes, and after forming the solder resist layer, it also includes A surface treatment layer is formed on the top surface of the conductive pad and the conductive hole.

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