CN217546397U - Soft and hard composite board - Google Patents

Abstract

The application provides a soft or hard composite sheet, includes: a flexible circuit board having at least one additional layer; and at least two rigid circuit boards formed on the build-up surface of the flexible circuit board, wherein each rigid circuit board is provided with at least one completely cured insulating glue area, a copper foil area covering the insulating glue area, a chemical copper plating layer covering the copper foil area and an electroplating copper layer covering the chemical copper plating layer, and the insulating glue area is not provided with glass fibers.

Description

Soft and hard composite board

Technical Field

The present application relates to a flexible composite board, and more particularly, to a technique for fabricating a rigid printed circuit board by performing multiple layer-adding processes on a fabricated flexible printed circuit board.

Background

The soft and hard composite board is mainly formed by combining a flexible circuit board (herein, sometimes referred to as a soft board) and a hard circuit board (herein, sometimes referred to as a hard board), and can combine the flexibility of the soft board and the strength of the hard board, so that the soft and hard composite board is often applied to a component carrier of an electronic product.

In the soft and hard composite board in the prior art, after the soft board and the hard board are respectively manufactured, the soft board and the hard board are pressed together to form the soft and hard composite board, wherein before the pressing, the hard board is grooved in advance, and after the pressing, the groove exposes out of the soft board, so that the soft and hard composite board has flexibility at the groove, and the hard board can be assembled with surface mounted devices (surface mounted devices). The above process is complicated and expensive, and it is obvious to those skilled in the art how to improve the prior art.

SUMMERY OF THE UTILITY MODEL

The technical problem that this application will be solved lies in providing one kind and need not make the hardboard in advance and to fluting the hardboard, then with soft board, the hard board is with the soft hard composite sheet of pressfitting.

In order to achieve the above and other objects, the present application provides a soft and hard composite panel, comprising: a flexible circuit board having at least one additional layer; and at least two hard circuit boards formed on the layer-adding surface of the flexible circuit board, wherein each hard circuit board is provided with at least one completely cured insulating glue area, a copper foil area covering the insulating glue area, a chemical copper plating layer covering the copper foil area and an electric copper plating layer covering the chemical copper plating layer, and the insulating glue area is not provided with glass fibers.

The flexible circuit board is attached with the back adhesive copper foil for multiple times and subjected to multiple layer increasing treatment, so that the purpose that the rigid board can be manufactured by slotting the rigid board without manufacturing the rigid board in advance is achieved, and due to the fact that the back adhesive copper foil is used for the multiple layer increasing treatment, the board thickness uniformity of the rigid board is improved, and therefore the tolerance of the board thickness of the rigid board can be reduced. In addition, because the hard board is formed on the flexible circuit board through multiple layer adding treatments, the process provides a designer of electronic products with higher design freedom.

Further details of the present application will be described with reference to the drawings.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIGS. 1-11 are schematic views of a process according to one embodiment of the present application;

fig. 12-13 are schematic process diagrams illustrating another process flow for via hole formation according to another embodiment of the present application.

Description of the symbols

1A, 1B: semi-finished product of soft and hard composite board

10: flexible wiring board 11: dielectric layer

12: the flexible board circuit 13: layer-adding surface

20: adhesive-backed copper foil 21: copper foil layer

211: first copper foil region 212: second copper foil region

213: intermediate copper foil zone 22: insulating glue layer

221: first insulating glue region 222: second insulating glue area

223: intermediate insulating glue zone 23: conducting hole

30: copper layer electroless plating 40: electroplated copper layer

50A, 50B: hard circuit board

Detailed Description

The positional relationship described in the following embodiments includes: the top, bottom, left and right, unless otherwise indicated, are based on the orientation of the elements in the drawings.

The present application discloses a manufacturing process of a flexible composite board, which is described below with reference to fig. 1 to 11, wherein the circuit design of the flexible board and the hard board is simplified for illustrative purposes, but the actual circuit design is not limited thereto.

Referring to fig. 1, a flexible printed circuit 10 is shown, the flexible printed circuit 10 has flexibility and includes at least a dielectric layer 11 and a flexible printed circuit 12, and the flexible printed circuit 10 can be manufactured by a conventional method. If a rigid wiring board is to be fabricated on both sides of the flexible wiring board 10, the flexible wiring board 10 will have two build-up layers 13; if the flex circuit board 10 is fabricated on only one side of the flex circuit board 10, the flex circuit board 10 will have only one build-up layer 13. In this embodiment, both surfaces of the flexible wiring board 10 are build-up surfaces 13.

Then, carrying out multiple layer-adding treatments on at least one surface of the flexible circuit board to form at least two rigid circuit boards on the flexible circuit board, wherein at least one layer-adding treatment comprises the following steps:

step (1):

referring to fig. 2 and 3, a back-adhesive copper foil 20 is respectively attached to two additional layers 13 of a semi-finished product 1A of a soft-hard composite board to be added; the soft and hard composite board semi-finished product refers to a state of the soft and hard composite board just before the soft and hard composite board is manufactured, i.e. the flexible circuit board 10 itself is the next "soft and hard composite board semi-finished product" just before the layer adding surface 13 of the flexible circuit board 10 is subjected to the first layer adding treatment. The back adhesive copper foil 20 is provided with a copper foil layer 21 and an insulation adhesive layer 22 of a B-Stage (B-Stage), the insulation adhesive layer 22 is coated on the copper foil layer 21, the insulation adhesive layer 22 does not contain glass fiber, and the build-up surface 13 is in contact with the insulation adhesive layer 22 but not in contact with the copper foil layer 21; the insulating adhesive layer 22 may be, for example, an epoxy-based, acrylic-based, polyimide-based, photo-and/or thermal-curable resin, and the B-stage refers to a state where the curable resin is not completely cured but is dried to have a finger-touch drying property; according to the characteristics of photocuring and/or thermocuring, the resin in the B stage can be completely cured to the C stage under the irradiation of specific light waves and/or at a specific curing temperature; in the present invention, the insulating adhesive layer 22 is maintained at the B stage before the step (4). The copper foil layer 21 is provided with a first copper foil area 211 positioned on one side of the soft and hard composite board semi-finished product 1A, a second copper foil area 212 positioned on the other side of the soft and hard composite board semi-finished product 1A and a middle copper foil area 213 connected between the first copper foil area 211 and the second copper foil area 212, and the first copper foil area 211 and the second copper foil area 212 are not contacted with each other; the insulating glue layer 22 has a first insulating glue region 221 located on one side of the soft-hard composite board semi-finished product 1A, a second insulating glue region 222 located on the other side of the soft-hard composite board semi-finished product 1A, and an intermediate insulating glue region 223 connected between the first and second insulating glue regions 221, 222, the first and second insulating glue regions 221, 222 are not contacted with each other, and the first and second insulating glue regions 221, 222 and the intermediate insulating glue region 223 are covered by the first and second copper foil regions 211, 212 and the intermediate copper foil region 213, respectively.

Step (2):

referring to fig. 4, the middle copper foil region 213 is removed, thereby exposing the middle insulation paste region 223. In a possible embodiment, the intermediate copper foil region 213 is removed by conventional methods such as attaching a photoresist, exposing, developing, etching, etc., but not limited thereto, and may be removed by laser engraving, for example.

And (3):

referring to fig. 5, the middle insulation paste region 223 is removed by using an etching solution, which is a chemical that can remove the B-stage insulation paste layer in contact therewith. After the middle insulating adhesive area 223 is removed, the middle portion of the flexible printed circuit board 10 may be exposed, thereby recovering the flexibility of the middle portion.

And (4):

according to the photo-curing and/or thermal curing characteristics of the insulation resin layer 20, the insulation resin layer 20 in the B-stage can be completely cured under the irradiation of a specific light wave and/or at a specific curing temperature, and the appearance thereof can maintain the appearance shown in fig. 5.

And (5):

as shown in fig. 6, first, the first and second copper foil regions 211 and 212 are respectively windowed, and then as shown in fig. 7, the first and second insulating adhesive regions 221 and 222 are windowed at the positions corresponding to the copper windows, so that at least one via hole (via) 23 is formed in the first and second copper foil regions 211 and 212 and the first and second insulating adhesive regions 221 and 222. The above-mentioned copper window and the window-opening method can be realized by dry (e.g. laser engraving) or wet (e.g. using chemical agent) method.

And (6):

a electroless copper plating layer 30 is formed on the soft-hard composite board semi-finished product 1B (i.e., in the state shown in fig. 6) by electroless plating, resulting in the state shown in fig. 8.

And (7):

as shown in fig. 9, an electroplated copper layer 40 is formed on the electroless copper plating layer 30 by circuit means.

And (8):

as shown in fig. 10, the first and second copper foil regions 211 and 212, the electroless copper plating layer 30, and the electrolytic copper plating layer 40 are patterned to form a desired circuit pattern.

Thereafter, the second build-up process may be continued to form a circuit pattern as shown in fig. 11. In the case where the soft and hard composite board is subjected to the layer adding process twice in total, the structures subjected to the layer adding process twice shown in fig. 11 are the hard circuit boards 50A and 50B. That is, the manufactured soft and hard composite board comprises a flexible printed circuit board 10 and at least two hard printed circuit boards 50A and 50B, wherein the hard printed circuit boards 50A and 50B are formed on the increasing layer of the flexible printed circuit board 10, each hard printed circuit board has at least one completely cured first and second insulating glue regions 221 and 222 (both are insulating glue regions), first and second copper foil regions 211 and 212 (both are copper foil regions) covering the insulating glue regions, a chemical copper plating layer 30 covering the copper foil regions, and a copper plating layer 40 covering the chemical copper plating layer 30, wherein the insulating glue regions do not have glass fiber.

In the foregoing embodiment, the via hole 23 is formed after the step (4). In the embodiment shown in fig. 12 and 13, the via hole 23 may be formed before step (4); specifically, as shown in fig. 12, during the process of removing the intermediate copper foil region 213 in step (2), a copper window may be opened in the first and second copper foil regions 211 and 212, and then, as shown in fig. 13, during the process of removing the intermediate insulating adhesive region 223, an etching solution may be used to open a window in the first and second insulating adhesive regions 221 and 222, and then the first and second insulating adhesive regions 221 and 222 are completely cured, so as to form the via hole 23.

The above-described embodiments and/or implementations are only illustrative of the preferred embodiments and/or implementations for implementing the technology of the present application, and are not intended to limit the implementations of the technology of the present application in any way, and those skilled in the art can make many changes and modifications to the other equivalent embodiments without departing from the scope of the technology disclosed in the present disclosure, but should be regarded as the technology and implementations substantially the same as the present application.

Claims (1)

1. A soft and hard composite board, comprising:

a flexible circuit board having at least one additional layer; and

the hard circuit boards are formed on the build-up surface of the flexible circuit board and each hard circuit board is provided with at least one completely cured insulating glue area, a copper foil area covering the insulating glue area, a chemical copper plating layer covering the copper foil area and an electroplating copper layer covering the chemical copper plating layer, wherein the insulating glue area does not contain glass fiber.

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