KR101086693B1 - A method for manufacturing a flexible copper clad laminate with excellent crack resistance - Google Patents

Abstract

The present invention relates to a method for producing flexible copper clad laminates (FCCL) having excellent flex resistance, and more particularly, copper foil is formed on a polymer film by sputtering, and the gloss, leveler content, and current conditions are thereon. The present invention relates to a method for producing a flexible copper foil laminated plate that is significantly improved in flex resistance by adjusting to form a copper plating layer.

Flex resistance, ductility, copper foil, laminated sheet, manufacturing

Description

A method of manufacturing a flexible copper foil laminate having excellent flex resistance {A METHOD FOR MANUFACTURING A FLEXIBLE COPPER CLAD LAMINATE WITH EXCELLENT CRACK RESISTANCE}

The present invention relates to a method for producing flexible copper clad laminates (FCCL) having excellent flex resistance, and more particularly, copper foil is formed on a polymer film by sputtering, and the gloss, leveler content, and current conditions are thereon. The present invention relates to a method for producing a flexible copper foil laminated plate that is significantly improved in flex resistance by adjusting to form a copper plating layer.

Flexible copper-clad laminates are used as the original boards of printed circuit boards. The flexible copper-clad laminates are divided into three-layer copper-laminated laminates laminated with an adhesive between copper foil and an insulating material, and two-layer copper-laminated laminates laminated without an adhesive, depending on the structure.

The three-layer copper-clad laminate has a disadvantage in that it is inexpensive and easy to manufacture, but has a disadvantage in that it is inferior in heat resistance due to the use of an adhesive and has a limitation in lowering the circuit wiring width.

The two-layer copper-clad laminate includes a casting method of coating and curing a polyimide solution on a copper foil and a sputtering method of thickening copper by electroplating the copper on a polyimide film.

There are two types of electroplating used in the sputtering method: gloss plating and matt plating. In the case of glossy plating, surface roughness can be improved to some extent by current control, but there is a problem in that desorption may occur during drive IC chip bonds due to low surface roughness. On the other hand, when the matte plating, the surface roughness is too high, the surface is rough and there is a limit in implementing a fine pattern. In addition, there is a disadvantage in that the flexural resistance is weak due to the poor surface density.

The base materials of the copper electroplating solution are copper sulfate and sulfuric acid. In order to obtain a uniform film quality while maintaining high productivity, an appropriate combination of additives should be added to the copper plating solution composed of the base material. Polishing agents, levelers and chlorine ions are used as additives to achieve this purpose.

The brightener is adsorbed on the surface of the cathode during plating and participates in the charge exchange reaction. In particular, the catalyst and the Cu ^{2 +} ions, while the reduction reaction to increase the deposition rate of the copper.

The leveler serves to lower the current efficiency by adsorbing on the cathode surface. Adsorption on the surface is influenced by mass transfer or charge transfer, so it is concentrated on the protrusion or corner to lower the electrodeposition rate of copper.

Chlorine ions are adsorbed on both the anode and the cathode. At the cathode, the leveler helps to stably adsorb to the cathode, thereby increasing the effect of the leveler. It also adsorbs on the anode to increase the rate of dissolution of copper.

Copper-clad laminates are mainly used in COF (chip on film) and FPC (flexible printed circuit) of mobile phones, monitors, TVs, and digital cameras, and are increasingly used in harsh environments due to increased information transmission capacity and increased exposure to external environments. In particular, the copper foil laminated sheet manufactured by sputtering method is low in bending resistance, so when exposed to severe external environment, it is highly likely to cause fatal defects of the product such as short circuit of the circuit wiring. It is required.

The present invention is to solve the problems of the prior art as described above, the present invention is to provide a method for improving the flex resistance by adjusting the content and current conditions of the polisher and leveler in manufacturing a flexible copper foil laminate. Shall be.

In order to achieve the above object, the present invention comprises the steps of (1) surface treatment of the base film; (2) depositing a copper thin film on the surface treated base film; And (3) the copper film deposited base film in a copper electroplating solution composition containing 1-4 ml / L of varnish and 10-40 ml / L leveler, starting at least 1 A / dm ² and up to 5 A / It provides a method for producing a flexible copper foil laminated plate comprising; forming a copper plating layer on a copper thin film by electroplating under the conditions of sequentially increasing the applied current up to dm ² .

According to this invention, the flexible copper foil laminated board which remarkably improved the bending resistance can be manufactured easily.

Hereinafter, the manufacturing method of the flexible copper foil laminated board of this invention is demonstrated in detail.

In the flexible copper foil laminated sheet manufacturing method of this invention, in the said (1) step, the base film of a copper foil laminated board is surface-treated. As the base film, a polymer film suitable as a base material of a flexible copper foil laminate such as a polyimide film, a teflon film, a PET film, a PC film, etc. may be used without limitation, and preferably a polyimide film is used.

The surface treatment of the base film is to improve adhesion or heat resistance between the insulating material and the metal, and may be performed by a conventional surface treatment method such as irradiating plasma or ion beam, but is not limited thereto. Preferably, the surface of the base film is treated using an ion beam, more preferably an oxygen ion beam.

In the method for producing a flexible copper foil laminate of the present invention, in step (2), a copper thin film is deposited on the surface-treated base film. The deposition of the copper thin film can be carried out by a known method, and is preferably deposited by sputtering.

The thickness of the copper thin film to be deposited is preferably 1000 to 6000 kPa, more preferably 2000 to 5000 kPa. If the thickness of the deposited copper thin film is less than 1000Å, the thickness of copper is thin, which may cause not only electrical resistance during electroplating but also pinhole generation. If the thickness of the copper foil exceeds 6000Å curl may occur because the thickness is thick, and the deposition time takes a long time during vacuum deposition, there is a problem that the productivity is reduced.

In the method for producing a flexible copper foil laminate of the present invention, in the step (3), the base film on which the copper thin film is deposited is contained in a copper electroplating solution composition containing a gloss agent of 1-4 ml / L and a leveler of 10-40 ml / L. A copper plating layer is formed on the copper thin film by electroplating under conditions of increasing the applied current sequentially starting at least 1A / dm ² up to 5A / dm ² .

As the brightening agent, alkyl sulfonate compounds, polyethylene glycol compounds, inorganic compounds and mixtures thereof are preferably used, and more preferably alkyl sulfonate compounds. Specific examples of such alkyl sulfonate compounds include silicon-containing dimethyl sulfonate, silicon-containing diethyl sulfonate, and the like.

The concentration of the brightener in the copper electroplating solution composition is 1-4 ml / L. If the gloss agent concentration is less than 1 ml / L, there is a problem that the flex resistance of the copper foil is lowered. If the gloss agent concentration is more than 4 ml / L, the improvement of physical properties is not seen and the additive cost is increased.

As the leveler, an organic silane sulfate compound, a polyvinylimidazolium compound, a polyvinylpyrrolidone compound, and a mixture thereof are preferably used, and more preferably an organic silane sulfate compound is used. Specific examples of such organosilane sulfate compounds include silyl dioxane sulfate compounds, silyl ether sulfate compounds, and siloxane sulfate compounds.

The concentration of the leveler in the copper electroplating solution composition is 10-40 ml / L. If the leveler concentration is less than 10ml / L there is a problem that the flex resistance of the copper foil is inferior, if it exceeds 40ml / L there is a disadvantage that the additive cost increases without improving the physical properties of the copper foil.

In step (3), the copper electroplating solution composition further includes copper sulfate, sulfuric acid, and chlorine ions in addition to the above-described brightener and leveler. There is no particular limitation on the concentration of these essential ingredients, and it can be appropriately selected within the range in which efficient copper plating can occur. A typical concentration of the copper sulfate is 50 ~ 100g / L, the concentration of sulfuric acid is 50 ~ 150g / L, and chloride ion (Cl ^-) concentration is not intended to be 20 ~ 70ppm or, which limits.

In step (3), copper electroplating is performed under conditions of sequentially increasing the applied current starting at least 1A / dm ² up to 5A / dm ² . Preferably, starting at least 1A / dm ² 0 ~ 1A / dm ² sequentially in 1 to 10 minutes Current increases up to 5A / dm ² To reach In the electroplating step, the current condition applied initially is 1A / dm ² If it falls short, the flex resistance of the copper foil is deteriorated. If the final current condition is beyond 5A / dm ² , the plating speed is increased, which causes scratches on the copper foil.

In addition to the essential steps described above, the flexible copper foil laminate manufacturing method of the present invention may further include conventional post-treatment steps such as after-plating anti-rust treatment, if necessary,

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the following Examples are only illustrative to help understanding of the present invention, but the present invention is not limited thereto.

Example  And Comparative example

The polymer film polyimide (PI, kapton 150E from Dupont) was surface treated with an oxygen ion beam. Surface treatment conditions are as follows:

Ion beam energy per unit area of 400 cm ² : 750 eV

Current density: 0.64 mA / cm ²

Ion irradiation amount: 1x10 ¹⁷ ion / cm ²

A copper (pure 99.99%) thin film was deposited on the surface-treated polyimide film by using a direct current magnetron sputtering method. Sputtering deposition was performed by injecting argon gas into an inert gas to maintain a vacuum degree of about 1x10 ^-3 torr and applying a DC voltage of 15 W / cm ² , and moving the substrate at a speed of 0.5 m / min on each film. Copper was continuously deposited. The thickness of the deposited copper thin film was 3000 mm 3.

The plating layer was formed by electroplating using a copper sulfate plating solution on the deposited copper thin film. Plating solution is 75 g / L of copper sulfate (CuSO ₄ · 5H ₂ O), 109 g / L of sulfuric acid (H ₂ SO ₄ ), 50 ppm of chlorine ions (Cl ⁻ ), and dimethyl sulfonic acid containing ETN-1-A, Si from Uyemura Salt) containing 0.5 to 4 ml / L and a leveler (sulphate compound including Uyemura's ETN-1-B, propanol and silyl ether and siloxane) at a concentration of 5 to 40 ml / L. Star polish and leveler concentrations are shown in Table 1 below.

Electroplating was carried out at room temperature, the electrode was used a copper-containing copper electrode, the current applied during electroplating 3A by increasing from 0 to 1 A / dm ^{2 in} 3 minutes starting from 1A / dm ² (1 step) / dm ² (six levels) (hereinafter referred to as 'reference current'). The step-by-step current application conditions were as follows. The thickness of the finally obtained electroplating was 8 micrometers.

The flex resistance of the flexible copper foil laminate specimens prepared as described above was measured using a flex resistance tester. More specifically, after the specimen was bitten by the jig, the jig reciprocated 70 times while reciprocating 90 degrees to the left and right, and the crack size of the sample was measured by an optical microscope. The bending resistance measurement method is schematically shown in FIG. 1, and the measurement results are shown in Table 1 below.

As a result of the flex resistance test, 100% of cracks formed in the copper thin film layer of the specimen were formed over the entire transverse direction of the specimen, and 100% of the cracks were formed over the transverse portion of the specimen. The crack length relative to time is expressed as a percentage. Therefore, the lower the numerical value of the flex resistance (%) in Table 1 means that the superior flex resistance.

2 shows micrographs of the case of 100% crack and 20% crack. Comparative Examples 1 to 3 correspond to a case where cracks are all 100%, and Example 3 corresponds to a case where cracks are 20%.

As can be seen from Table 1, Comparative Examples 1 to 3 out of the range of the present invention in any one of the leveler and the brightener concentration in the plating solution composition was very poor in flex resistance.

Next, after fixing the gloss concentration to 2 ml / L and the leveler concentration to 20 ml / L as in Example 4, copper plating was performed with varying the intensity of the applied current. The method of increasing the current by dividing into six steps was the same as described above, but the relative current intensity was changed from the reference current. The applied relative current intensities are shown in Table 2 below.

For the obtained specimens, the flex resistance was measured in the same manner as described above. The relative crack length (%) when the crack length of Example 4 is 100 is shown in Table 2 below.

As can be seen from Table 2, when the initial applied current is less than 1A / dm ² (Comparative Examples 4-6), even if the same plating using the same plating composition in the same manner, the flex resistance is relatively poor.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows schematically the bending resistance measuring method of the flexible copper foil laminated board of this invention.

Figure 2 is a micrograph of the case of 100% cracks and 20% cracks as a result of measuring the bending resistance of the flexible copper foil laminate of the present invention.

Claims (8)

(1) surface treating the base film; (2) depositing a copper thin film on the surface treated base film; And (3) The base film on which the copper thin film is deposited is placed in a copper electroplating solution composition containing 1 to 4 ml / L polish and 10 to 40 ml / L leveler, starting at least 1 A / dm ² for 1 to 10 minutes. Sequentially increasing the applied current by 0 ~ 1A / dm ^{2 in} units and electroplating under the condition of finally reaching a maximum of 5A / dm ² to form a copper plated layer on the copper thin film. Way. The manufacturing method of the flexible copper foil laminated board of Claim 1 whose base film is a polyimide film. The method according to claim 1, wherein the surface treatment in step (1) is performed using an oxygen ion beam. The method of manufacturing a flexible copper foil laminate according to claim 1, wherein the deposition of the copper thin film in the step (2) is performed by a sputtering method, and the thickness of the deposited copper thin film is 1000 to 6000 kPa. The method for producing a flexible copper foil laminate according to claim 1, wherein the brightening agent is an alkylsulfonate compound. The method according to claim 1, wherein the leveler is an organosilane-based sulfate compound. delete The flexible copper foil laminated board manufactured by the method in any one of Claims 1-6.

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