KR20080087622A - Double sided flexible copper clad laminate without a adhesive layer, flexible printed circuit board using the flexible copper clad laminate, and fabrication methods of the flexible copper clad laminate and the flexible printed circuit board - Google Patents

Abstract

A double-sided FCCL(Flexible Copper Clad Laminate) without an adhesive layer, an FPCB(Flexible Printed Circuit Board) using the same, and manufacturing methods thereof are provided to simplify the entire manufacturing process by forming the double-sided FCCL through surface treatment and electroplating of a single-sided FCCL. A manufacturing method for a double-sided FCCL includes the steps of: forming a single-sided FCCL by stacking a polyimide layer on a first copper foil layer with a cast method(101); forming a hydrophilic functional group by surface-treating the polyimide layer(102); forming a metal seed layer on the surface-treated polyimide layer(103); and forming a second copper foil layer on the polyimide layer by electroplating a surface of the polyimide layer on which the metal seed layer is formed(104).

Description

Double sided flexible copper clad laminate without a adhesive layer, flexible printed circuit board using the flexible copper clad laminate, and fabrication methods of the flexible copper clad laminate and the flexible printed circuit board}

The present invention relates to a material of a printed circuit board (PCB) used in a semiconductor device, and a PCB, and more particularly, to a flexible copper clad laminate (FCCL), and a flexible printed circuit board (FPCB) using the same, and fabrication thereof. It is about a method.

Generally, FCCL is composed of a flexible polyimide layer and a copper foil layer, and is produced in such a manner that a copper foil layer is laminated on a polyimide film, or a polyimide layer is laminated on a copper foil layer. The manufacturing method of FCCL includes a cast method and an adhesion method. The cast method is to form a polyimide layer on the copper foil layer by applying a polyimide varnish on the copper foil layer and then performing heat treatment under appropriate conditions. In the case of FCCL produced by the cast method, the adhesive strength between the copper foil layer and the polyimide layer is excellent, and the manufacturing cost thereof is low. However, the FCCL produced by the cast method is not suitable for forming a fine circuit pattern because the interface between the copper foil layer and the polyimide layer is rough. On the other hand, an adhesion method is to adhere a copper foil layer using an adhesive film on a polyimide film. In the case of FCCL manufactured by the adhesive method, the adhesive film is weak to heat, and copper ions of the copper foil layer may move in the adhesive film layer in an environment of high temperature and high pressure to cause a short circuit between circuit wirings. Therefore, it is difficult for FCCL produced by the adhesive method to be applied to high-density and densified FPCB.

On the other hand, the FCCL used in the FPCB is classified into a single-sided FCCL and a double-sided FCCL according to the structure. In the single-side FCCL, the copper foil layer is laminated only on one side of the polyimide layer, and in the double-sided FCCL, the copper foil layer is laminated on both sides of the polyimide layer. Recently, as electronic devices have become smaller and more functional, the range and demand for FPCBs using double-sided FCCL are gradually increasing. 1 is a flowchart illustrating a manufacturing process of an FPCB according to the related art, and illustrates a process of manufacturing an FPCB using a double-sided FCCL. Referring to FIG. 1, first, an additional copper foil layer is attached to the polyimide layer of the prepared cross-section FCCL using an adhesive film (step 10). As a result, the double-sided FCCL in which the copper foil layer was laminated | stacked on both surfaces of a polyimide layer is formed. Thereafter, through-holes are formed in the double-sided FCCL (step 20). The double-sided FCCL having the through-holes formed is electroless plated to form a conductive layer on the through-hole inner wall (step 30). Further, electrolytic plating is performed on both sides of the electroless plated FCCL to completely fill the through-holes with the conductive layer (step 40). Thereafter, the circuits set on both sides of the electrolytic plating double-sided FCCL are patterned (step 50). As a result, the FPCB having the circuit patterns set on both sides is completed. However, since the FPCB manufactured by the above-mentioned conventional manufacturing method includes an adhesive film, it has the above-mentioned heat resistance problem and the short circuit problem between circuit wiring. In addition, in the process of forming the double-sided FCCL of step 10, after the copper foil layer is attached to the polyimide layer by the adhesive film, heat and pressure are applied, so that the copper foil layer and poly of the cross-section FCCL previously formed by this heat and pressure The adhesive strength between the mid layers may be reduced, and the physical properties of the cross-sectional FCCL may be reduced.

Therefore, the technical problem to be achieved by the present invention is to increase the adhesive strength between the polyimide layer and the copper foil layers and to form a microcircuit pattern by surface treatment, vacuum deposition, and electroplating of the cross-sectional FCCL produced by the cast method. It is to provide a method of manufacturing a non-adhesive double-sided FCCL.

Another technical object of the present invention is to surface-treat, vacuum-deposit, and electroplat a single-sided FCCL produced by a cast method, thereby increasing the adhesive strength between the polyimide layer and the copper foil layers and forming a fine circuit pattern. To provide a self-adhesive double-sided FCCL.

Another technical problem to be achieved by the present invention is to increase the adhesive strength between the polyimide layer and the copper foil layers by forming a through-hole, electroplating, and patterning the cross-section FCCL manufactured by the cast method, and The present invention provides a method for manufacturing an FPCB capable of forming a circuit pattern.

Yet another technical problem to be achieved by the present invention is to increase the adhesive strength between the polyimide layer and the copper foil layers by forming a through-hole, electroplating and patterning the cross-section FCCL manufactured by the cast method, It is to provide an FPCB in which a microcircuit pattern can be formed.

In order to achieve the above-described technical problem, a method of manufacturing a non-adhesive double-sided FCCL according to the present invention includes a single-sided flexible copper clad by laminating a polyimide layer on a first copper foil layer using a cast method. forming a laminate; Surface treating the polyimide layer to form a hydrophilic functional group on the surface of the polyimide layer: forming a metal seed layer on the surface treated polyimide layer; And electroplating a surface of the polyimide layer on which the metal seed layer is formed so that a second copper foil layer is formed on the polyimide layer.

An adhesive-free double-sided FCCL according to the present invention for achieving the above-mentioned other technical problem includes a first copper foil layer, a polyimide layer, and a second copper foil layer. The polyimide layer is laminated on the first copper foil layer by a cast method. A 2nd copper foil layer is laminated | stacked on the said polyimide layer by surface treatment, metal seed layer formation, and an electroplating process.

According to another aspect of the present invention, there is provided a method of manufacturing an FPCB, which is formed by a cast method and has a structure in which a polyimide layer is laminated on a first copper foil layer. Forming a through-hole of the; Surface treating the polyimide layer to form a hydrophilic functional group on the surface of the polyimide layer of the at least one through-hole formed cross-section FCCL: forming a metal seed layer on the surface treated polyimide layer step; Electroplating the cross section FCCL on which the metal seed layer is formed so that a second copper foil layer is formed on the polyimide layer; And forming circuit wirings respectively set on the first and second copper foil layers.

The FPCB according to the present invention for achieving another technical problem described above includes a first circuit wiring layer, a polyimide layer, a second circuit wiring layer, and a contact plug. In the first circuit wiring layer, the first copper foil layer is patterned according to the first circuit wiring. The polyimide layer is laminated on the first copper foil layer by a cast method. As for a 2nd circuit wiring layer, the 2nd copper foil layer laminated | stacked on the said polyimide layer by surface treatment, metal seed layer formation, and an electroplating process is patterned according to 2nd circuit wiring. The contact plug is embedded in the through-hole formed to penetrate the polyimide layer and the first copper foil layer prior to the surface treatment process, whereby the plating layer is buried by the electrolytic plating process, thereby forming the first circuit wiring layer and the second circuit wiring layer. It is formed to connect electrically.

As described above, the non-adhesive double-sided FCCL according to the present invention, and the FPCB using the same and a method for manufacturing the same, surface-treated and electroplated the single-sided FCCL produced by the cast method to form a double-sided FCCL, so that the entire manufacturing process is simplified. The two-sided FCCL can be formed without the adhesive layer, the adhesive strength between the polyimide layer and the copper foil layers can be increased, and a finer circuit pattern can be formed.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention and to those skilled in the art. It is provided for complete information.

2 is a flow chart showing a manufacturing process of the adhesive-free FCCL according to an embodiment of the present invention. First, by using a cast method, as shown in FIG. 3A, the polyimide layer 120 is laminated on the first copper foil layer 110, thereby forming a cross-section flexible copper clad laminate (FCCL) 100a. (Step 101). Here, the cast method forms a polyimide layer 120 on the first copper foil layer 110 by applying a polyimide varnish on the copper foil layer and then performing heat treatment under appropriate conditions. Thereafter, as shown in FIG. 3B, the polyimide layer 120 is surface treated (step 102). As a result, a hydrophilic functional group 130 is formed on the surface of the polyimide layer 120 as shown in FIG. 3C. Here, the surface treatment of the polyimide layer 120 may be made by irradiating an ion beam on the surface of the polyimide layer 120. Optionally, the ion beam may be irradiated onto the surface of the polyimide layer 120 in a reactive gas atmosphere. In this case, the hydrophilic functional group 130 may be better formed on the surface of the polyimide layer 120 than when the ion beam is irradiated on the surface of the polyimide layer 120 without the reactive gas. The reactive gas may include at least one of 0 ₂ , N ₂ , CO ₂ , NO, NH ₃ , and H ₂ O. Alternatively, the surface treatment of the polyimide layer 120 may be performed by plasma treatment or corona treatment.

Thereafter, a metal seed layer 140 is formed on the surface-treated polyimide layer 120 (step 103). The metal seed layer 140 may include a first seed layer 141 and a second seed layer 142. In this case, the first seed layer 141 may include any one of Ni, Cr, and Cu. In addition, the first seed layer 141 may include an alloy including at least one of Ni, Cr, and Cu. In more detail, for example, the first seed layer 141 includes any one of an alloy of Ni and Cr, an alloy of Cr and Cu, and an alloy of Ni and Cu, or Ni, Cr, and Cu. It may include an alloy of. In addition, the first seed layer 141 may include an alloy of any one or two of Ni, Cr, and Cu and another metal. The second seed layer 142 comprises Cu. Optionally, metal seed layer 140 may be formed of a single layer comprising Cu. In FIG. 3D, the metal seed layer 140 including the first and second seed layers 141 and 142 is formed on the polyimide layer 120 as an example. In step 103, a sputtering process or an evaporation process may be performed to form the metal seed layer 140 on the polyimide layer 120. Thereafter, the surface of the polyimide layer 120 on which the metal seed layer 140 is formed is electroplated (step 104). As a result, as shown in FIG. 3E, a double-sided FCCL 100b having a structure in which the first copper foil layer 110, the polyimide layer 120, and the second copper foil layer 150 are sequentially stacked is formed. .

Meanwhile, in the surface treatment process of step 102, the adhesion between the second copper foil layer 150 and the polyimide layer 120 formed later may change according to the change of surface treatment conditions. The change in adhesive force between the second copper foil layer 150 and the polyimide layer 120 according to the change of surface treatment conditions may be represented as shown in the table below.

Sample Peel Strength (N / cm) Single-sided FCCL products manufactured by conventional cast method 14.8 Surface Treatment Condition 1 10.7 Surface treatment condition 2 15.9 Surface Treatment Conditions 3 17.0

In Table 1, surface treatment conditions 1 to 3 may be, for example, a surface treatment by an ion beam, depending on a change in the irradiation amount of the ion beam. As such surface treatment conditions change, lower levels (surface treatment conditions 1), equivalent levels (surface treatment conditions 2), and higher levels (surfaces) compared to the adhesion of single-sided FCCL products produced by conventional cast methods The double-sided FCCL 100b having the adhesive force of the processing condition 3) can be manufactured.

As described above, the double-sided FCCL 100b and the manufacturing method thereof according to the present invention, since the double-sided FCCL 100b does not include an adhesive film, the polyimide layer 120, the second and second copper foil layers ( The adhesive strength between the 110 and 150 may be increased. In addition, it is possible to form a finer circuit pattern using the double-sided FCCL (100b) according to the present invention.

4 is a flowchart illustrating a manufacturing process of an FPCB according to an embodiment of the present invention. First, in a set region of the cross-sectional FCCL 200a formed by a cast method and having a structure in which a polyimide layer 220 is laminated on the first copper foil layer 210 as shown in FIG. 5A, FIG. 5B. At least one through-hole 230 is formed as shown in step 201. Thereafter, as shown in FIG. 5C, the polyimide layer 202 of the cross-section FCCL 200a in which the through-holes 230 are formed is subjected to surface treatment (step 202). As a result, hydrophilic functional groups 240 are formed on the surface of the polyimide layer 202 as shown in FIG. 5D. Here, since the surface treatment of the polyimide layer 202 is substantially the same as step 102 described above with reference to FIG. 2, a detailed description thereof will be omitted.

Thereafter, a metal seed layer 250 is formed on the surface-treated polyimide layer 202 (step 203). Since step 203 is the same as step 103 described above with reference to FIG. 2, a detailed description thereof will be omitted. In addition, the components of the metal seed layer 250 are the same as those of the metal seed layer 140 described above with reference to FIG. 3D. The cross-section FCCL 200b in which the metal seed layer 250 is formed is electroplated (step 204). As a result, as shown in FIG. 5F, a double-sided FCCL 200c having a structure in which the first copper foil layer 210, the polyimide layer 220, and the second copper foil layer 260 are sequentially stacked is formed. . Further, by the electroplating of step 204, the inner wall of the through-hole 230 formed in step 201 is plated, and the through-hole 230 is completely embedded by the plating layer, so that the contact plug 261 is formed. Is formed. The contact plug 261 is made of the same metal component as the second copper foil layer 260. On the other hand, the contact plug 261 electrically connects the circuit wiring layer 211 formed by the first copper foil layer 210 and the circuit wiring layer 262 formed by the second copper foil layer 260 in step 205 described later. Connect.

Next, by forming circuit wirings set on the first and second copper foil layers 210 and 260 of the double-sided FCCL 200c, respectively, the FPCB 200d is completed (step 205). Referring to step 205 in more detail, first, as shown in FIG. 5G, photoresist 270 is applied to the first and second copper foil layers 210 and 260 of the double-sided FCCL 200c, respectively. Then, it exposes and develops and patterns. Thereafter, the patterned photoresist 270 is used as an etching mask to etch the double-sided FCCL 200c. As a result, as shown in FIG. 5H, an FPCB 200d having circuit wiring layers 211 and 262 formed on both surfaces of the polyimide layer 220 is obtained.

As described above, the FPCB 200d and the manufacturing method using the double-sided FCCL 100b according to the present invention, since the double-sided FCCL 100b does not include an adhesive film, the polyimide layer 220, The adhesive strength between the second copper foil layers 210 and 260 may increase. In addition, since the first copper foil layer 210 is formed by a cast method, the first copper foil layer 210 may have a high adhesive strength property, and the second copper foil layer 260 may be formed by an electroplating method, and thus may have a fine circuit implementation. have. As a result, circuit wiring having a somewhat wider wiring width may be implemented using the first copper foil layer 210, and circuit wiring having a fine wiring width may be implemented using the second copper foil layer 260. In addition, the through-holes 230 are plated together by an electroplating process for forming the second copper foil layer 260 on one surface of the polyimide layer 220, so that the inner wall of the through-holes 230 is previously formed. The electroless plating process, and the electrolytic plating process, which were separately carried out for plating, can be omitted. Therefore, the time and cost for manufacturing the FPBC 200d can be reduced, and defects that can occur in the existing electroless plating process and the electrolytic plating process can be reduced, so that the production yield of the FPBC 200d can be improved. . In addition, since the thickness of the second copper foil layer 260 may be freely adjusted according to the characteristics of the semiconductor device to be applied in the electroplating process, it may provide a variety of circuit design.

1 is a flowchart illustrating a manufacturing process of an FPCB according to the related art.

2 is a flow chart showing a manufacturing process of the adhesive-free FCCL according to an embodiment of the present invention.

3A to 3E are cross-sectional views illustrating a manufacturing process of the adhesive-free FCCL shown in FIG. 2.

4 is a flowchart illustrating a manufacturing process of an FPCB according to an embodiment of the present invention.

5A to 5H are cross-sectional views illustrating a manufacturing process of the FPCB shown in FIG. 4.

<Explanation of symbols for main parts of drawing>

100a, 200a, 200b: single sided FCCL 100b, 200c: double sided FCCL

110 and 210: first copper foil layer 120 and 220: polyimide layer

130, 240: hydrophilic functional group 140, 250: metal seed layer

141 and 251: first seed layer 142 and 252: second seed layer

150 and 260: 2nd copper foil layer 211 and 262: circuit wiring layer

230: Through-hole 261: Contact plug

Claims (20)

Forming a cross-section flexible copper clad laminate (FCCL) by laminating a polyimide layer on the first copper foil layer by using a cast method; Surface treating the polyimide layer to form a hydrophilic functional group on the surface of the polyimide layer: Forming a metal seed layer on the surface treated polyimide layer; And A method of manufacturing a non-adhesive double-sided FCCL comprising electroplating a surface of the polyimide layer on which the metal seed layer is formed such that a second copper foil layer is formed on the polyimide layer. The method of claim 1, wherein the surface treatment step, Method of manufacturing a non-adhesive double-sided FCCL comprising the step of irradiating the ion beam on the surface of the polyimide layer. The method of claim 1, wherein the surface treatment step, A method of producing a self-adhesive double-sided FCCL comprising irradiating an ion beam to a surface of the polyimide layer in a reactive gas atmosphere. The method of claim 3, The reactive gas is a method for producing a non-adhesive double-sided FCCL containing at least one of O ₂ , N ₂ , CO ₂ , NO, NH ₃ , and H ₂ O. The method of claim 1, wherein the surface treatment step, A method of manufacturing a non-adhesive double-sided FCCL comprising the step of plasma treatment, or the corona treatment of the surface of the polyimide layer. The method of claim 1, The metal seed layer comprises a first seed layer and a second seed layer, Forming the metal seed layer, Forming the first seed layer on the surface treated polyimide layer; And Forming a second seed layer on the first seed layer. The method of claim 6, The first seed layer comprises any one of Ni, Cr, and Cu, or comprises an alloy comprising at least one of Ni, Cr, and Cu, The second seed layer is a manufacturing method of the adhesive-free double-sided FCCL containing Cu. The method of claim 1, The metal seed layer is a method for producing a non-adhesive double-sided FCCL containing Cu. The method of claim 1, And in the step of forming the metal seed layer, a sputtering process or a thermal lamination process is performed to form the metal seed layer on the surface-treated polyimide layer. 1st copper foil layer; A polyimide layer laminated on the first copper foil layer by a cast method; And An adhesive-free double-sided FCCL comprising a second copper foil layer laminated on the polyimide layer by surface treatment, metal seed layer formation, and electroplating. Forming at least one through-hole in a predetermined region of the cross-section FCCL formed by a cast method and having a structure in which a polyimide layer is laminated on the first copper foil layer; Surface treating the polyimide layer such that hydrophilic functional groups are formed on a surface of the polyimide layer of the at least one through-hole formed cross section FCCL: Forming a metal seed layer on the surface treated polyimide layer; Electroplating the cross section FCCL on which the metal seed layer is formed so that a second copper foil layer is formed on the polyimide layer; And A method of manufacturing an FPCB, comprising forming circuit wirings respectively set in the first and second copper foil layers. The method of claim 11, wherein the surface treatment step, Irradiating an ion beam to the surface of the polyimide layer manufacturing method of FPCB. The method of claim 11, wherein the surface treatment step, Irradiating an ion beam onto a surface of the polyimide layer in a reactive gas atmosphere. The method of claim 13, The reactive gas is a method for producing an FPCB containing at least one of O ₂ , N ₂ , CO ₂ , NO, NH ₃ , and H ₂ O. The method of claim 11, wherein the surface treatment step, Method of producing a FPCB comprising the step of plasma or corona treatment of the surface of the polyimide layer. The method of claim 11, The metal seed layer comprises a first seed layer and a second seed layer, Forming the metal seed layer, Forming the first seed layer on the surface treated polyimide layer; And Forming a second seed layer on the first seed layer. The method of claim 16, The first seed layer comprises any one of Ni, Cr, and Cu, or comprises an alloy comprising at least one of Ni, Cr, and Cu, And the second seed layer comprises Cu. The method of claim 11, And the metal seed layer comprises Cu. The method of claim 11, In the step of forming the metal seed layer, a sputtering process or a thermal lamination process is performed to form the metal seed layer on the surface-treated polyimide layer. A first circuit wiring layer including a first copper foil layer patterned according to the first circuit wiring; A polyimide layer laminated on the first copper foil layer by a cast method; A second circuit wiring layer including a second copper foil layer laminated on the polyimide layer by surface treatment, metal seed layer formation, and electroplating, and patterned according to second circuit wiring; And In order to electrically connect the first wiring layer and the second wiring layer by embedding a plating layer by the electrolytic plating process in a through-hole formed to penetrate the polyimide layer and the first copper foil layer before the surface treatment process. An FPCB comprising a formed contact plug.

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