KR101890036B1 - Manufacturing method of four-layer structure flexible copper clad laminate - Google Patents

Abstract

A method for producing a flexible copper-clad laminate having a four-layer structure which is excellent in interlaminar adhesion and can prevent unfilled defects due to surface roughness of the copper foil layer.
The method for manufacturing a flexible copper clad laminate having a four-layer structure according to the present invention comprises the steps of: (a) coating a polyimide resin composition on an upper surface of a first copper layer and curing the polyimide resin layer to form a polyimide resin layer; (b) coating an upper surface of the second copper foil layer with an epoxy resin composition and drying to form a semi-cured epoxy resin layer; (c) laminating the first and second copper layers so that the polyimide resin layer and the semi-curable epoxy resin layer face each other; And (d) curing the semi-cured epoxy resin layer to form a flexible copper-clad laminate having a four-layer structure in which a first copper layer, a polyimide resin layer, an epoxy resin layer, and a second copper layer are sequentially arranged from above; And a control unit.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a flexible copper clad laminate having a four-layer structure,

The present invention relates to a method of manufacturing a flexible copper clad laminate, and more particularly, to a method of manufacturing a flexible copper clad laminate having a four-layer structure which is excellent in interlaminar adhesive strength and can prevent unfilled defects due to surface roughness of a copper foil layer .

Copper Clad Laminate (CCL) is a raw material for a printed circuit board (PCB), and mainly phenol resin, epoxy resin or the like is impregnated with an insulator such as glass fiber or graft paper, And then the copper foil is heat-pressed.

Such a copper-clad laminate can be classified into a paper base phenol resin copper-clad laminate, a glass base epoxy resin copper-clad laminate, a paper base polyester resin copper-clad laminate, a composite copper-clad laminates, a flexible copper- A copper clad laminate for a printed wiring board, and a high-frequency copper clad laminate.

In recent years, the wireless charging technology has been applied to the smart portable terminal, and the charging efficiency has been increasingly important. In accordance with this, the thickness of the copper foil applied to the circuit material of the flexible copper clad laminate is getting thicker.

Thus, several inevitable problems arise in producing a flexible copper-clad laminate having a large thickness of copper foil.

First, the most important thing is that the interlayer adhesion must be high. This is because, if the adhesive force is low after the copper foil is etched, a problem arises that a circuit which is etched by an external impact is more easily fallen than a product obtained by etching a thin copper foil.

Second, when the existing three-layer structure manufacturing method is applied, there may be a problem with quality depending on the roughness of the copper foil. Particularly, as the thickness of the copper foil increases, the surface roughness tends to increase. As described above, the three-layer method is a method in which a thermoplastic resin is melted and thermocompression-bonded to a copper foil. In this case, if the surface roughness of the copper foil is large, the thermoplastic resin layer can not fill all the parts. The etchant penetrates into the voids at the time of etching to induce etching failure.

Third, there is a problem in that productivity is lowered when the existing three-layer structure manufacturing method is applied. In the conventional three-layer manufacturing method, a thin film of thermoplastic resin is used between the copper foils, and the thermoplastic resin is melted at a very high temperature to produce the product through the copper foil and the thermocompression bonding. At this time, if the copper foil is thick, it takes a long time to transfer heat to the thermoplastic resin through the copper foil, which results in a decrease in productivity.

As a solution to this problem, a flexible copper clad laminate manufacturing method of a five-layer structure has been proposed. However, the flexible copper-clad laminate having a five-layer structure has low heat resistance and poor dimensional stability, and thus has many problems in the FPCB manufacturing process and also has a problem in that efficiency against heat generated during charging is inferior.

A related prior art is Korean Patent Laid-Open No. 10-2012-0117439 (published on October 24, 2012), which discloses a method for manufacturing a flexible copper clad laminate.

An object of the present invention is to provide a method for manufacturing a flexible copper clad laminate having a four-layer structure which is excellent in interlaminar adhesive strength and can prevent unfilled defects due to surface roughness of the copper foil layer.

According to another aspect of the present invention, there is provided a method for manufacturing a flexible copper clad laminate having a four-layer structure, comprising: (a) coating a polyimide resin composition on an upper surface of a first copper foil layer and curing the polyimide resin layer to form a polyimide resin layer ; (b) coating an upper surface of the second copper foil layer with an epoxy resin composition and drying to form a semi-cured epoxy resin layer; (c) laminating the first and second copper layers so that the polyimide resin layer and the semi-curable epoxy resin layer face each other; And (d) curing the semi-cured epoxy resin layer to form a flexible copper-clad laminate having a four-layer structure in which a first copper layer, a polyimide resin layer, an epoxy resin layer, and a second copper layer are sequentially arranged from above; And a control unit.

The method for manufacturing a flexible copper clad laminate having a four-layer structure according to the present invention has a four-layer structure in which a first copper layer, a polyimide resin layer, an epoxy resin layer and a second copper foil layer are sequentially arranged from above, And the first and second fillers are added to the polyimide resin layer and the epoxy resin layer at an optimum content ratio, respectively, so that the surface of the polyimide resin layer Improvement in roughness can improve interlaminar adhesion.

Also, in the method for manufacturing a flexible copper clad laminate having a four-layer structure according to the present invention, even if the thickness of the first and second copper foil layers is increased to increase the charging efficiency, the polyimide resin solution and the epoxy Since the insulator is formed by coating the resin solution, the insulator can be completely filled up to the bent portion by the roughness of the copper foil, so that the unfilled defects due to the copper foil roughness are eliminated and no defect is caused in the etching process .

In the method for manufacturing a flexible copper clad laminate having a four-layer structure according to the present invention, a polyimide resin layer is formed only on the first copper layer, a semi-cured epoxy resin layer is formed on the second copper layer, Curing to form a four-layer structure, the use amount of the expensive polyimide resin can be reduced, the manufacturing process can be simplified, and the structure can be thinned.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart showing a method of manufacturing a flexible copper clad laminate having a four-layer structure according to an embodiment of the present invention.
2 to 5 are process sectional views showing a method of manufacturing a four-layered flexible copper-clad laminate according to an embodiment of the present invention.
6 is a SEM photograph of an FCCL prepared according to Example 4. Fig.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. However, it should be understood that the present invention is not limited to the embodiments disclosed herein but may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a method for manufacturing a four-layered flexible copper-clad laminate according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a process flow diagram illustrating a method of manufacturing a flexible copper-clad laminate having a four-layer structure according to an embodiment of the present invention, and FIGS. 2 to 5 illustrate a method of manufacturing a flexible copper- Fig.

1, a method of manufacturing a flexible copper clad laminate having a four-layer structure according to an embodiment of the present invention includes forming a polyimide resin layer on a first copper layer (S110), forming a semi-cured epoxy resin Layer formation step S120, a first and second copper foil layer lining step S130, and a semi-curing epoxy resin layer curing step S140.

A polyimide resin layer is formed on the first copper layer

1 and 2, a polyimide resin composition is coated on the upper surface of the first copper foil layer 110 in the polyimide resin layer formation step (S110) on the first copper foil layer and cured to form a polyimide resin layer The resin layer 120 is formed.

In this case, the coating may be applied to various types of substrates such as a comma coating method, a die coating method, a lip coating method, a roll coating method, a gravure coating method, a blade coating method, a bar coating method, A coating method, a reverse coating method, or the like can be used. The curing can be carried out at 300 to 400 占 폚.

Copper having a relatively high electrical conductivity may be used as the material of the first copper layer 110. The first copper layer 110 may have a relatively thick thickness of 30 to 105 占 퐉 in order to improve the charging efficiency when a smart portable terminal to which a wireless charging technique is applied to the smart portable terminal.

The polyimide resin composition is composed of a polyimide resin, a first filler, and a first solvent. In this step, the first solvent is volatilized and removed by drying the polyimide resin composition so that the polyimide resin layer 120 is composed of the polyimide resin 122 and the first filler 124.

At this time, the polyimide resin 122 has a heat resistance of 200 占 폚 or more and is excellent in adhesion to an epoxy resin (142 in Fig. 3). Such a polyimide resin 122 has a flexible characteristic, so that not only the bending property can be improved but also defects such as cracks in the curved portion can be prevented in advance. In addition, the polyimide resin 122 can maintain an appropriate withstand voltage characteristic even in the thickness of the thin film.

The first filler 124 improves the surface roughness of the interface and improves the interlayer adhesion. The first filler 124 is preferably added in an amount of 10 to 30% by weight based on 100% by weight of the entire polyimide resin layer 120. When the addition amount of the first filler 124 is less than 10% by weight with respect to 100% by weight of the entire polyimide resin layer 120, the effect of improving the interlayer bonding strength is difficult to exhibit because the added amount is insignificant. On the contrary, when the amount of the first filler 124 added is more than 30% by weight based on 100% by weight of the entire polyimide resin layer 120, the interlayer interface adhesion is improved but the withstand voltage characteristic is lowered.

The first filler 124 may be selected from the group consisting of silica, alumina, aluminum hydroxide, titania, magnesium oxide, kaolin, talc, montmorillonite, calcium carbonate, barium carbonate, barium titanate, potassium titanate, calcium sulfate, Barium, calcium primary phosphate, secondary calcium phosphate, calcium tertiary phosphate and the like may be used.

The first filler 124 may be an amorphous type or a ball type, and FIG. 2 shows a band-shaped amorphous type. At this time, the first filler 124 preferably has an average diameter of 100 nm to 5 μm. When the average diameter of the first filler 124 is less than 100 nm, there is a problem that the adhesion and heat resistance are deteriorated due to the problem of dispersibility of particles as the size of the first filler 124 is reduced. Conversely, if the average diameter of the first filler 124 exceeds 10 mu m, the insulating layer thickness may increase and the thermal resistance may increase.

The first solvent may be any organic solvent, and may be used without particular limitation. Specifically, at least one solvent selected from dimethylacetamide, N-methylpyrrolidone, methyl ethyl ketone, toluene, methyl isobutyl ketone, chlorobenzene, benzyl alcohol, Can be used.

At this time, the polyimide resin layer 120 preferably has a thickness of 4 to 50 mu m. If the thickness of the polyimide resin layer 120 is less than 4 占 퐉, the withstand voltage characteristic is deteriorated, and it may be difficult to secure an appropriate strength. On the contrary, when the thickness of the polyimide resin layer 120 exceeds 50 탆, the thermal resistance increases.

Forming a semi-cured epoxy resin layer on the second copper foil layer

1 and 3, an epoxy resin composition is coated on the upper surface of the second copper foil layer 130 in the semi-cured epoxy resin layer formation step (S120) on the second copper foil layer and dried to obtain a semi-cured epoxy resin A resin layer 145 is formed.

At this time, the drying is performed at 100 to 200 ° C for 1 to 30 minutes, and the second solvent is removed and dried to make the semi-cured state.

The semi-curable epoxy resin composition 145 is composed of an epoxy resin 142, a second filler 144, a curing agent (not shown) and a second solvent.

Examples of the epoxy resin 142 include cresol novolack type epoxy resin, phenol novolac type epoxy resin, bisphenol type epoxy resin, dicyclopentadiene type epoxy resin, linear aliphatic epoxy resin, An epoxy resin, a heterocyclic epoxy resin, and the like may be used.

The second filler 144 serves to improve heat resistance and flame retardancy of the epoxy resin layer 140 (FIG. 5). The second filler 144 is preferably added in an amount of 30 to 60% by weight based on 100% by weight of the entirety of the semi-cured epoxy resin layer 145. When the addition amount of the second filler 144 is less than 30% by weight based on 100% by weight of the entirety of the semi-curable epoxy resin layer 145, the addition amount is insignificant, and the heat resistance and flame retardancy characteristics are deteriorated. On the contrary, when the amount of the second filler 144 added exceeds 60% by weight based on 100% by weight of the entirety of the semi-curable epoxy resin layer 145, there is a problem that the adhesive force with the copper foil decreases.

The second filler 144 may be the same as the first filler, or a different material may be used. In addition, the second pillar 144 may be an amorphous type or a ball type as in the case of the first filler, and FIG. 3 shows that the ball type is applied. At this time, it is preferable that the second pillars 144 have an average diameter of 100 nm to 5 μm.

The curing agent includes 3,3'-dichloro-4,4'-diaminodiphenylmethane, 2,2 ', 3,3'-tetrachloro-4,4'-diaminodiphenylmethane, 4,4'- Aminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, and 3,4'-diaminodiphenyl sulfone , Novolak resins including phenol novolac resins, cresol novolak resins, and naphthol novolac resins, and the like.

The second solvent may be an organic solvent without particular limitation. Specifically, at least one selected from the group consisting of dimethylacetamide, N-methylpyrrolidone, methyl ethyl ketone, toluene, methyl isobutyl ketone, chlorobenzene, and benzyl alcohol may be used as the second solvent .

The first and second copper foil layers

1 and 4, in the first and second copper foil layer lamination step S130, the polyimide resin layer 120 and the semi-cured epoxy resin layer 145 are disposed so as to face each other, Layers 110 and 130 are laminated together.

At this time, it is preferable that the laminate is carried out using a laminate roll under the condition of 40 to 100 ° C. Here, the laminate roll is formed by pressing the second copper foil layer 130, in which the first copper foil layer 110 in which the polyimide resin layer 120 is laminated and the semi-curable epoxy resin layer 145 are laminated, In a manner that maintains the above-mentioned structure. Accordingly, the upper surface 110a of the first copper foil layer 110 and the upper surface 130a of the second copper foil layer 130 face each other.

Semi-curable epoxy resin curing

1 and 5, in the semi-curing epoxy resin layer curing step S140, the semi-curable epoxy resin layer 145 (FIG. 4) is fully cured at 100 to 200 ° C to form an epoxy resin layer 140 do. Thus, the flexible copper-clad laminate 100 having the four-layer structure in which the first copper layer 110, the polyimide resin layer 120, the epoxy resin layer 140, and the second copper foil layer 130 are sequentially arranged from above .

At this time, it is preferable that the epoxy resin layer 140 has a thickness of 4 to 50 μm. If the thickness of the epoxy resin layer 140 is less than 4 mu m, it may be difficult to ensure adhesion with the polyimide resin layer 120. [ On the contrary, when the thickness of the epoxy resin layer 140 is more than 50 탆, the thickness of the epoxy resin layer 140 can be increased only without increasing the effect.

The method for manufacturing a flexible copper clad laminate having a four-layer structure according to an embodiment of the present invention has a four-layer structure in which a first copper layer, a polyimide resin layer, an epoxy resin layer, and a second copper layer are sequentially arranged from above And the polyimide resin layer to be bonded to the epoxy resin layer can ensure heat resistance and the first and second fillers are added to the polyimide resin layer and the epoxy resin layer at the optimum content ratio, The interlayer adhesion can be improved by improving the surface roughness.

In addition, in the method for manufacturing a flexible copper clad laminate having a four-layer structure according to an embodiment of the present invention, in order to increase the charging efficiency, even if the thickness of the first and second copper foil layers becomes thick, Since the insulator is formed by coating the solution and the epoxy resin solution, the insulator can be completely filled up to the bent portion by the roughness of the copper foil, so that the poor filling due to the copper foil roughness is eliminated, .

Further, in the method of manufacturing a flexible copper clad laminate having a four-layer structure according to an embodiment of the present invention, a polyimide resin layer is formed only on the first copper layer, a semi-cured epoxy resin layer is formed on the second copper layer, Since the epoxy resin has a four-layer structure by curing the epoxy resin, the use amount of the expensive polyimide resin can be reduced, the manufacturing process can be simplified, and the structure can be thinned.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

1. Manufacture of FCCL

FCCL according to Examples 1 to 5 and Comparative Examples 1 to 3 were prepared with the compositions shown in Table 1.

In Examples 1 to 5 and Comparative Examples 2 and 3, a polyimide resin composition comprising a polyimide resin, a first filler, talc, and NMP (N-methylpyrrolidone) was mixed on the upper surface of a copper foil having a thickness of 35 μm Coated to a thickness of 30 탆 by a bar coating method, and cured at 360 캜 to form a polyimide resin layer. Next, an epoxy resin composition prepared by mixing bisphenol A type epoxy, alumina (Al ₂ O ₃ ) as a second filler, and cresol novolak resin and methyl ethyl ketone as a second curing agent was coated on the upper surface of a 35 μm thick copper foil And dried at 120 ° C to form a semi-cured epoxy resin layer. At this time, the second filler was added at a content ratio of 50% by weight based on the total weight of the semi-curable epoxy resin layer. Next, the first and second copper foil foils were laminated using a laminate roll at 80 캜 under the condition that the polyimide resin layer and the semi-curable epoxy resin layer were opposed to each other. Next, the semi-curable epoxy resin layer was cured at 160 占 폚 to prepare a four-layered FCCL.

At this time, in Comparative Example 1, FCCL was prepared in the same manner as in Example 1, except that the first filler was not added.

[Table 1] (unit:% by weight)

2. Microstructure Observation

6 is a SEM photograph showing the FCCL prepared according to Example 3. Fig.

6, the FCCL manufactured according to Example 3 includes a first copper layer 110, a polyimide resin layer 120, an epoxy resin layer 140, and a second copper foil layer 130 Layer structure arranged in order. Here, an amorphous type is applied to the first pillar 124, and a ball type is applied to the second pillar 144.

Since the polyimide resin layer 120 and the epoxy resin layer 140 are formed by coating on the first and second copper layers 110 and 130 on both sides of the FCCL manufactured according to the third embodiment, 1 and the bent portions of the surfaces of the second copper foil layers 110 and 130 are completely filled with the insulator without fail.

3. Property evaluation

Table 2 shows the physical property evaluation results of the FCCL prepared according to Examples 1 to 5 and Comparative Examples 1 to 3.

1) Surface roughness

Surface roughness of PI surface was measured using AFM (Atomic Force Microscope).

2) Peel strength

The peel strength between the PI side and the epoxy side was measured by the IPC-TM-650 2.4.9 method in which the 4-layer FCCL was cut to a width of 12.7 mm and then peeled at an angle of 90 °.

3) Withstand voltage test

The FCCL was cut into a size of 100 mm * 100 mm, one copper foil was etched to a size of 25Φ, and the reverse voltage was measured under the condition that the copper foil on the opposite side was original. (IPC-TM-650 2.5.6)

[Table 2]

Referring to Tables 1 and 2, it can be seen that, in the case of FCCL prepared according to Examples 1 to 5, as the amount of the filler to be added increases, the surface roughness improves, and the peel strength is improved. However, in the case of the FCCL prepared according to Examples 1 to 5, the withstand voltage characteristic was lowered as the filler amount was increased, but the target value of 4.0 kV / mil or more was satisfied.

On the other hand, Comparative Example 1 in which the filler was not added and Comparative Example 2 in which the amount of the filler was less than the range suggested in the present invention showed good withstand voltage characteristics, but had no or little improvement in surface roughness and had a peel strength of 0.93 kgf / in And 1.10 kgf / in, indicating that the adhesive strength was poor.

In Comparative Example 3 in which the addition amount of the filler exceeded the range suggested by the present invention, the peeling strength was improved due to the improvement in surface roughness, but the withstand voltage characteristic was drastically lowered to be less than the target value.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. These changes and modifications may be made without departing from the scope of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.

S110: forming a polyimide resin layer on the first copper foil layer
S120: Step of forming a semi-cured epoxy resin layer on the second copper foil layer
S130: First and second copper foil layer laminating step
S140: Semi-curing type epoxy resin layer curing step

Claims (9)

(a) coating a polyimide resin composition on an upper surface of a first copper foil layer and curing the polyimide resin composition to form a polyimide resin layer;
(b) coating an upper surface of the second copper foil layer with an epoxy resin composition and drying to form a semi-cured epoxy resin layer;
(c) laminating the first and second copper layers so that the polyimide resin layer and the semi-curable epoxy resin layer face each other; And
(d) curing the semi-curable epoxy resin layer to form a flexible copper-clad laminate having a four-layer structure in which a first copper layer, a polyimide resin layer, an epoxy resin layer, and a second copper layer are sequentially arranged from above, ≪ / RTI &
The polyimide resin composition is composed of a polyimide resin, a first filler, and a first solvent, and the semi-curable epoxy resin composition is composed of an epoxy resin, a second filler, a curing agent and a second solvent,
The first filler is added in an amount of 15 to 30 wt% based on 100 wt% of the entire polyimide resin layer, and the second filler is added in an amount of 30 to 60 wt% based on 100 wt% of the entire epoxy resin layer ,
The peel strength between the polyimide resin layer and the epoxy resin layer is 1.53 to 1.71 Kgf / in,
Wherein the flexible copper-clad laminate has a withstanding voltage of 4.32 to 6.15 kV / mil.
The method according to claim 1,
Each of the first and second copper foil layers
And a thickness of 30 to 105 占 퐉.
delete delete The method according to claim 1,
The polyimide resin layer
Layer structure having a thickness of 4 to 50 mu m.
delete The method according to claim 1,
The epoxy resin layer
Layer structure having a thickness of 4 to 50 mu m.
The method according to claim 1,
Each of the first and second pillars
And examples of the inorganic filler include silica, alumina, aluminum hydroxide, titania, magnesium oxide, kaolin, talc, montmorillonite, calcium carbonate, barium carbonate, barium titanate, potassium titanate, calcium sulfate, barium sulfate, Calcium carbonate, and calcium tertiary phosphate. 2. The method of manufacturing a flexible copper clad laminate according to claim 1,
9. The method of claim 8,
Each of the first and second pillars
Wherein the copper foil has an average diameter of 100 nm to 5 占 퐉.

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