KR101395904B1 - Manufacturing multilayer flexible printed circuit board - Google Patents

Abstract

The present invention relates to a method of manufacturing a multilayer flexible circuit board, and more particularly, to a method of manufacturing a multilayer flexible circuit board, comprising: (a) preparing an inner layer substrate member by laminating copper layers on both upper and lower sides of the PI layer, (b) forming a plurality of first via holes by emitting a laser to a designated position on both upper and lower surfaces of the inner layer substrate member prepared in the step (a), and (c) (D) forming a plurality of first blind vias and a first copper plating layer by plating a surface of the inner layer substrate member on which a plurality of first via holes are formed, (E) forming an outer layer substrate member on the surface of the inner layer substrate member on which the circuit pattern is formed by the step (d), and removing the first copper plating layer and the copper foil layer formed on the surface of the inner layer substrate member, (F) performing the step (e) Forming a plurality of second via holes by emitting a laser to a designated position on a surface of an outer layer substrate member joined to a surface of the inner layer substrate member; (g) forming a second via hole by the step (f) Forming a plurality of second blind via holes and a second copper plating layer on the surface of the outer layer substrate member so as to complete the flexible circuit board to form a plurality of blind via holes into the upper and lower copper plates, The land for forming the via hole is reduced by forming a stack symmetrically with respect to the copper foil layer on either side of the layer to realize a high density interconnection (HDI) FPCB, The present invention provides a flexible circuit board manufacturing method which can be easily carried out and which can achieve high-density wiring and circuit configuration.

Description

TECHNICAL FIELD [0001] The present invention relates to a multilayer flexible printed circuit board

The present invention relates to a method of manufacturing a multilayer flexible circuit board, and more particularly, to a method of manufacturing a multilayer flexible circuit board by stacking a plurality of blind via holes symmetrically with respect to a copper foil layer on either side of upper and lower copper foil layers layer flexible printed circuit board (FPCB), which is capable of realizing High Density Interconnection (FPCB) by reducing the number of lands for forming via holes.

Recently, with the tendency of miniaturization, thinning, and high density of electronic products, multilayer printed circuit boards are also complicated with layer composition of the circuit along with changes of raw materials in accordance with design freedom and trend of electronic products. In addition, development of an interlaminar conductive method for a high-density printed circuit board (PCB) has been demanded in order to cope with speeding up of signal processing and miniaturization (thin and light).

The types of the flexible printed circuit boards described above are roughly classified into cross sections, both sides, and multilayers depending on the positions where the circuit patterns are formed and the number thereof.

Among them, the one-sided flexible printed circuit board is formed on only one side of the circuit pattern, so that the mounting density of components is low and the manufacturing method is simple.

The double-sided flexible printed circuit board has circuit patterns formed on both upper and lower surfaces, and upper and lower circuits are connected through through holes.

A multilayer flexible printed circuit board is a three-dimensional circuit board having an inner layer circuit and an outer layer circuit, and has advantages of high-density component mounting by a three-dimensional wiring and shortening of a wiring distance.

The manufacturing process of such a flexible printed circuit board (FPCB) is performed by laminating a dry film on a copper-clad laminate (FCCL) having a copper foil formed on a base film and then laminating a predetermined circuit pattern And then a cover lay film is temporarily bonded to protect the circuit board surface.

Each copper-clad laminate to which the coverlay film is adhered as described above is laminated using a bonding sheet, and then a through hole or a via hole is formed by using an NC drill, and through an electroless plating and an electrolytic plating process, A multilayer flexible circuit board is manufactured by forming a plating layer on the copper foil layer, electrically connecting necessary layers to each other, and then bonding the coverlay film to the outermost layer copper foil.

In Korean Patent Laid-Open Publication No. 2007-0019199 (published on February 15, 2007), a copper laminate formed by laminating a copper foil layer on a polyimide resin is sequentially exposed, developed, and etched to form a circuit pattern, Layer flexible printed circuit board, and a method for producing a multilayer flexible printed circuit board by laminating a plurality of copper-clad laminated boards on which a circuit pattern is formed by using an interlayer adhesive, wherein the coverlay film and the interlayer adhesive And the unnecessary portion is removed by the laser beam irradiated by the laser in the process of manufacturing the flexible printed circuit board.

On the other hand, in the manufacturing process of a general flexible printed circuit board, since the substrate having a circuit is extremely thin with a thickness of 27 to 43 탆, the substrate may be wrinkled during the manufacturing process, defective circuit may be formed, There was a problem.

In addition, an expensive double-side exposure apparatus is required in the exposure process, and the entire process is carried out in a single-sheet manner, resulting in a decrease in productivity, an increase in defect rate, and an increase in manufacturing cost.

Accordingly, in the case of the build-up printed circuit board, a micro-via hole, that is, a blind via hole is formed to form selective electrical conduction between the layers. In the multilayer flexible circuit board, The blind via hole (BVH) can not be directly formed on the IVH, thereby forming a blind via hole after forming an additional land.

In the present invention, a plurality of blind via holes are formed as a stack symmetrically with respect to a copper foil layer on either side of the upper and lower copper foil layers constituting an inner layer substrate member, lands for producing via holes are reduced, (High Density Interconnection) FPCB according to an embodiment of the present invention.

(B) a step of preparing an inner layer substrate member by laminating copper foil layers on both upper and lower sides of the PI layer with the PI layer as a center, (b) A step of forming a plurality of first via holes in a rhomboid shape that is narrowed inwardly toward the inner side by sequentially removing the PI layer from the upper copper layer or the PI layer from the lower copper layer at the specified position of the inner layer substrate member prepared by the step (D) forming a plurality of first blind vias and a first copper plating layer by copper plating on a surface of the inner layer substrate member on which a plurality of first via holes are formed by the step (b) Forming a circuit pattern by partially removing the first copper plating layer and the copper foil layer formed on the surface of the inner layer substrate member by the step (c); (e) forming a circuit pattern by the step (d) Layer substrate member, (F) joining an outer layer substrate member preliminarily impregnated with a matrix resin to a fibrillated fiber and an outer layer substrate member composed of a copper foil bonded to an outer surface of the interlayer adhesive; A plurality of second via holes are formed in the outer layer substrate member joined to the surface by laser to remove the outer substrate member so as to expose the first blind via and the counter circuit pattern and to form a rhombus shape narrowing toward the inner side (G) copper plating is performed on the surface of the outer layer substrate member on which the second via hole is formed by the step (f), and the copper layer on either side of the upper and lower copper layer forming the inner layer substrate member is referred to as And forming a second copper plating layer and a second blind via as a stack symmetrically with the first blind via of the first blind via to complete the flexible circuit board.

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The method for manufacturing a multilayer flexible circuit board according to the present invention has the following effects.

First, a plurality of blind via holes are formed in a stack symmetrically with respect to a copper foil layer on either side of the upper and lower copper foil layers forming the inner layer substrate member, lands for producing via holes are reduced, and HDI High Density Interconnection) FPCB can be implemented.

Second, via holes can be easily formed by laser, and high-density wiring and circuit configuration can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a manufacturing process of a multilayer flexible circuit board according to a conventional embodiment.
2 is a simplified block diagram of a multi-layer flexible circuit board method in accordance with an embodiment of the present invention.
3 is a schematic view illustrating a manufacturing process of a multilayer flexible circuit board according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately The present invention should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention, and not all of the technical ideas of the present invention are described. Therefore, at the time of the present application, It should be understood that variations can be made.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a simplified block diagram of a method of manufacturing a multilayer flexible circuit board according to an embodiment of the present invention. FIG. 3 is a cross- FIG. 4 is a schematic view illustrating a manufacturing process of a multilayer flexible circuit board according to an embodiment of the present invention; FIG.

The present invention relates to a method of manufacturing a multilayer flexible circuit board, and more particularly, to a method of manufacturing a multilayer flexible circuit board by stacking a plurality of blind via holes symmetrically with respect to a copper foil layer on either side of upper and lower copper foil layers layer flexible printed circuit board (FPCB) with high density interconnection (HDI), wherein the land for forming a via hole is reduced, and a method of manufacturing the multilayer flexible circuit board is described in detail with reference to FIGS. 2 and 3 The following is an example.

First, in step (a) (S100)

The inner layer substrate member 10 is prepared by laminating the copper foil layers 12 on both the upper and lower sides of the PI layer 11 with the PI layer 11 as the center.

At this time, the material of the PI layer 11 is made of a polyimide having excellent heat resistance, little change in characteristics according to temperature difference, good impact resistance, good dimensional stability, and excellent electrical characteristics (insulation) desirable.

And (b) in step S200,

The PI layer 11 in the upper side copper layer 12 or the PI layer 11 in the lower side copper layer 12 is formed at the specified position of the inner layer substrate member 10 prepared in the step (a) And a plurality of rhombic first via holes H1 are formed so as to become narrower toward the inward direction.

In this case, the number and position of the first via hole H1 formed in the step (b) are determined depending on the structure of the circuit, and the number and position of the first via hole H1 are not limited, The copper foil layer 12 and the PI layer 11 on one side are removed by a laser to form a copper foil layer 12 located on the back surface of the copper foil layer 12, ).

For example, when a first via hole H1 is formed on the upper surface of the innerlayer substrate member 10 with a laser, the first via hole H1 is positioned on the upper surface of the PI layer 11 located at the center of the innerlayer substrate member 10 The copper layer 12 and the PI layer 11 are sequentially removed by the laser so that the upper surface of the copper foil layer 12 located on the bottom surface of the PI layer 11 is electrically connected to the first via hole H1, Lt; / RTI >

Since the surface of the copper foil layer 12 reflects the laser beam, only the copper foil is removed from the copper foil layer 12 by etching using the same size as the diameter of the via hole to be processed, It is also possible to complete the first via hole H1 by emitting a laser beam with the same diameter as the via hole at the same position and processing the hole in the PI layer 11. [

And (c) in step S300,

The surface of the inner layer substrate member 10 on which the plurality of first via holes H1 are formed is plated by the step (b) (S200) to form a plurality of first blind via holes (BVH) 13 And the first copper plating layer 20 are formed.

The copper plating may be performed by either electrolytic or electroless plating and is plated on the inner circumferential surface of the first via hole H1 to form a first blind via hole (BVH) 13.

(D) In step S400,

The circuit pattern 21 is formed by partially removing the first copper plating layer 20 and the copper foil layer 12 formed on the surface of the innerlayer substrate member 10 by the step (c) (S300).

At this time, it is preferable that the first copper plating layer 20 and the copper foil layer 12 are removed from each other.

(E) In step S500,

The interlaminar adhesive 31 preliminarily impregnated with the matrix resin and the interlaminar adhesive 31 are formed on the surface of the inner layer substrate member 10 on which the circuit pattern 21 is formed by the step (d) The outer layer substrate member 30 made of the copper foil 32 bonded to the outer surface of the outer layer substrate member 30 is bonded.

The outer layer substrate member 30 to be bonded in step (e) (S500) includes an interlayer adhesive (prepreg) 31 preliminarily impregnated with a matrix resin in the reinforcing fiber, And the foil 32 is joined to form a single body.

The copper foil 32 is formed on the upper surface of the interlayer adhesive (prepreg) 31 after the interlayer adhesive (prepreg) 31 is laminated on the surface of the inner layer substrate member 10 on which the circuit pattern 21 is formed. Are stacked.

(F) In step S600,

The outer layer substrate member 30 bonded to the surface of the innerlayer substrate member 10 by the step (e) (S500) is exposed to the first blind via 13 and the counter circuit pattern 21, The outer substrate member 30 is removed by a laser to form a plurality of second via holes H2 which are in the form of a rhombus which narrows toward the inner side.

The second via hole H2 formed in step (f) is preferably formed in a rhombic shape that becomes narrower toward the inward side by the laser, and the outer layer substrate member 30 on one side is formed as a laser So that the circuit pattern 21 is exposed.

The second via hole H2 formed in the step (f) may be formed on the upper surface of the first via hole H1 formed in the step (b) And the lower copper foil layer 12 are symmetrical with respect to each other on the basis of the copper foil layer 12 on either side of the lower copper foil layer 12,

(G) step S700,

The surface of the outer layer substrate member 30 on which the second via hole H2 is formed is plated by the step (f) (S600) to form upper and lower copper foil layers 10, The second blind via 41 and the second copper plating layer 40 are stacked on the first blind via 13 symmetrically with respect to the first blind via 13 on either side of the first copper plating layer 12, Thereby completing the flexible circuit board.

At this time, it is preferable that the second via hole (H2) is completely filled with the copper plating and is formed as the second blind via (41).

At least three or more multi-layer flexible printed circuit boards may be manufactured by repeating the above-described steps (e) (S500) to (g) (S700).

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

H1: first via hole H2: second via hole
10: Inner layer substrate member 11: PI layer
12: copper foil layer 13: first blind via
20: first copper plating layer 21: circuit pattern
30: outer layer substrate member 31: interlayer adhesive (prepreg)
32: copper foil 40: second copper plating layer
41: second blind via

Claims (4)

(a) preparing an inner layer substrate member by laminating copper foil layers on both upper and lower sides of the PI layer with the PI layer as a center;
(b) a step of removing the PI layer from the upper copper layer or the PI layer from the lower copper foil layer in order by the laser, in a predetermined position of the inner layer substrate member prepared in the step (a) Forming a plurality of holes;
(c) forming a plurality of first blind via holes and a first copper plating layer by copper plating on the surface of the inner layer substrate member having the plurality of first via holes formed by the step (b);
(d) forming a circuit pattern by partially removing the first copper plating layer and the copper foil layer formed on the surface of the inner layer substrate member by the step (c);
(e) an outer layer substrate made of a copper foil bonded to the outer surface of the interlayer adhesive, and an interlayer adhesive, which is preliminarily impregnated with the matrix resin in the reinforcing fiber, on the surface of the inner layer substrate member on which the circuit pattern is formed by the step (d) Joining members;
(f) removing the outer substrate member with a laser to expose the first blind via and the counter circuit pattern to the outer layer substrate member bonded to the surface of the inner layer substrate member by the step (e) Forming a plurality of second via holes in a rhomboidal shape which becomes narrower and narrower;
(g) copper plating is performed on the surface of the outer layer substrate member on which the second via hole is formed by the step (f) to form a first copper layer on either the upper or lower copper layer, Forming a second copper plating layer on the second blind via and stacking the second blind via with the blind via to form a flexible circuit board. delete delete delete

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