JP2010042564A - Method for producing flexible substrate and flexible substrate - Google Patents

Abstract

A flexible base material such as a copper clad laminate capable of further improving the heat-resistant peel strength and a method for producing the same.
A polyimide film is vacuum-dried at a temperature of 60 ° C. or higher and 450 ° C. or lower, and a silane coupling agent 11 is applied to at least one surface of the polyimide film. It was set as the manufacturing method of the flexible base material which forms the metal layers 12, 13, and 14 in the coating layer 11 surface. Preferably, the polyimide film 1 is vacuum-dried at 1 × 10 ⁻² Torr or less, and hydrophilicity is imparted to the polyimide film surface to which the silane coupling agent is applied by plasma treatment. Moreover, the application layer of the silane coupling agent and the said metal layer were laminated | stacked in order on the polyimide film, and it was set as the flexible base material in which the silane coupling agent contains the chloromethyl group or the imidazole group.
[Selection] Figure 2

Description

  The present invention relates to a method for manufacturing a copper-clad laminate and other flexible substrates, and a flexible substrate, which are used for producing a printed wiring board built in an electronic device such as a mobile phone or a display.

  As one of the flexible base materials, a copper-clad laminate in which a metal layer such as a barrier layer or a copper layer mainly composed of nickel or the like is sequentially laminated on the surface of a polyimide film is known (Patent Literature). 1), the barrier layer in this copper-clad laminate has low adhesion to the polyimide film, so the copper layer is oxidized by the penetration of oxygen contained in moisture, etc., especially when placed in a high temperature atmosphere. Therefore, it is formed for the purpose of improving the peel strength by exhibiting the adhesion force by interposing between them. As a result, the normal peel strength of the copper-clad laminate with the barrier layer formed is improved, but the heat-resistant peel strength of the copper-clad laminate after being placed in a high-temperature atmosphere is currently expected to be further improved. It is rare.

  Furthermore, as such a copper-clad laminate for the purpose of improving adhesion, it is also known that a silane coupling treatment is performed on the surface of the polyimide film and then a copper layer is laminated on the silane coupling treatment surface. (See Patent Document 2), according to this copper-clad laminate, the adhesion between the polyimide film and the copper layer is improved by the silane coupling treatment, so that the normal peel strength is good.

  However, even if it is a copper-clad laminate subjected to such a coupling treatment, the heat-resistant peel strength after being placed in a high-temperature atmosphere will be reduced, so that it will be incorporated in various electronic devices in the future. However, a copper-clad laminate having a sufficient heat-resistant peel strength has not been obtained at present in producing printed wiring boards.

JP 2004-303863 A JP 2006-054357 A

  This invention is made | formed in view of this situation, and makes it a subject to provide flexible base materials, such as a copper clad laminated board which can aim at the further improvement of heat-resistant peel strength, and its manufacturing method.

  The present inventors have pursued the cause of the decrease in heat-resistant peel strength in a copper-clad laminate obtained by subjecting the surface of the polyimide film to silane coupling treatment. The present invention according to claims 1 to 4 is completed by finding that the plasticizer and the component derived from dimethylacetamide added during film processing evaporate as gas when placed in the film. It has come to be.

  That is, in the method for producing a flexible base material according to the first aspect of the present invention, after the polyimide film is vacuum-dried under a temperature condition of 60 ° C. or higher and 450 ° C. or lower, silane is applied to at least one surface of the polyimide film. A coupling agent is applied, and then a metal layer is formed on the surface of the coating layer of the silane coupling agent.

  Here, the vacuum means that at least the pressure is lower than the atmospheric pressure. Further, as the metal layer, a barrier layer mainly composed of nickel or the like is formed, and further, a copper layer such as a copper sputtered film or copper plating is formed on the barrier layer.

  Further, as this silane coupling agent, those containing an amino group, an epoxy group, a chloromethyl group, or an imidazole group are preferably used. Further, the concentration of the silane coupling agent is 0 with water or alcohol. A solution diluted to 0.01 to 10 wt% is used, and the film thickness after drying is 0.5 to 10 nm, preferably 1 to 5 nm.

  Invention of Claim 2 is a manufacturing method of the copper clad laminated board of Claim 1, WHEREIN: Hydrophilicity is provided to the surface of the said polyimide film which apply | coats the said silane coupling agent by plasma treatment. It is said.

According to a third aspect of the present invention, in the method for producing a copper-clad laminate according to the first or second aspect, the polyimide film is vacuum-dried at 1 × 10 ⁻² Torr or less.

  Invention of Claim 4 is a flexible base material obtained using the manufacturing method of the flexible base material as described in any one of Claim 1 thru | or 3, Comprising: The said silane coupling agent of the said polyimide film is obtained. The coating layer and the metal layer are laminated in order, and the silane coupling agent contains a chloromethyl group or an imidazole group.

  According to the invention according to any one of claims 1 to 3, the polyimide film is vacuum-dried under a temperature condition of 60 ° C. or higher and 450 ° C. or lower, thereby adding a plasticizer or a plasticizer added during film processing. The component derived from dimethylacetamide evaporates together with the water adhering or penetrating to become a dry state. Therefore, the adhesion between the polyimide film and the metal layer is improved by applying a silane coupling agent to the polyimide film after vacuum drying and forming the metal layer on the surface of the coating layer of the silane coupling agent. Thus, a flexible substrate having excellent normal peel strength can be obtained. In particular, when the flexible substrate is placed in a high temperature atmosphere by vacuum drying, components such as moisture and plasticizer evaporate from the polyimide film and penetrate the metal layer to oxidize the metal layer. It can prevent, and the fall of heat-resistant peel strength can be suppressed.

  In that case, according to invention of Claim 2, the adhesiveness of a polyimide film and a silane coupling agent is improved by providing hydrophilicity to the surface of the polyimide film which apply | coats a silane coupling agent by plasma treatment. Can be made. Preferably, the adhesion improving effect is effectively obtained by imparting hydrophilicity by plasma treatment immediately before applying the coupling agent after vacuum drying.

The vacuum drying is preferably performed at 1 × 10 ⁻² Torr or less as in the invention described in claim 3. This is because the thermal load acting on the polyimide film can be reduced by preventing the temperature condition from becoming unnecessarily high by performing it under a pressure of 1 × 10 ⁻² Torr or less.

  According to the invention described in claim 4, particularly excellent normal peel strength and heat-resistant peel strength can be obtained by using a silane coupling agent containing a chloromethyl group or an imidazole group.

Hereinafter, the manufacturing method of the copper clad laminated board which concerns on this invention is demonstrated.
The manufacturing method in this embodiment has a vacuum drying process, a silane coupling agent application process, and a metal layer formation process in this order, and between this vacuum drying process and the silane coupling agent application process. It has a plasma treatment process for imparting hydrophilicity. Therefore, description will be given below in the order of the above steps.

First, prepare the polyimide film having a thickness of 20Myuemu～50myuemu, the polyimide film by the vacuum drying step, 60 ° C. or higher 450 ° C. or less, preferably at a temperature of 0.99 ° C. or higher 350 ° C. or less, 1 × 10 ^-2 Vacuum dry below Torr. At this time, this vacuum drying treatment time is 40 minutes or more and 1 hour 20 minutes or less, and as the polyimide film becomes thicker within the range of the film thickness, the required time is longer in the vacuum drying time. Make time.

  As a result, the polyimide film is dried by evaporating the plasticizer and the component derived from dimethylacetamide added during film processing together with moisture adhering to or penetrating the film. (End of vacuum drying process)

  Next, after the polyimide film thus dried is released under atmospheric pressure, plasma treatment is performed on one surface of the polyimide film by a plasma treatment process to impart hydrophilicity. (End of plasma treatment process)

  Next, a silane coupling agent is apply | coated to the hydrophilicity provision surface by the said plasma treatment in a polyimide film by a silane coupling agent application | coating process, and it is made to dry at normal temperature. In this case, the silane coupling agent contains an amino group, an epoxy group, a chloromethyl group or an imidazole group, preferably a chloromethyl group or an imidazole group, more preferably a chloromethyl group, and the concentration thereof is water or A solution diluted to 0.01 to 10 wt% with alcohol or the like is used, and the coating amount of this silane coupling agent is adjusted so that the film thickness when dried is in the range of 0.5 to 10 nm. Is done. Then, the coating layer by the silane coupling agent which has high adhesiveness with respect to the hydrophilic provision surface of a polyimide film is formed. (End of silane coupling agent application process)

  Next, after a barrier layer (metal layer) made of an alloy of nickel and chromium is formed on the surface of the coating layer using a sputtering apparatus in the metal layer forming step, a copper sputter layer (metal layer) is formed on the surface of the barrier layer. A metal layer) is formed, and then a copper plating layer (metal layer) is formed by a plating apparatus.

Here, as the sputtering apparatus, for example, a DC magnetron sputtering apparatus 5 shown in FIG. 1 is used.
The sputter device 5 is configured to have a substantially circular cross section, and a rotary drum 50 having a cylindrical appearance is installed at the center thereof with its axial direction directed vertically. Along with this, a plurality of barrier layer targets 61 and a plurality of copper sputter layer targets 62 are sequentially installed from the upstream side to the downstream side in the conveyance direction of the polyimide film 1. The targets 61 and 62 for the barrier layer and the copper sputter layer are respectively fixed to a backing plate (not shown) and are detachable from the sputtering apparatus 5 together with the plate. Accordingly, the number of targets 61 and 62 can be adjusted with respect to each other, and a partition wall member 55 is provided between each target 61 and 62.

  Further, the DC magnetron sputtering apparatus 5 has an internal pressure adjusting means for keeping the inside in a vacuum and an internal atmosphere adjusting means for adjusting the whole inside to an inert gas atmosphere such as argon gas. In addition, the sputtering apparatus 5 Inside, there is provided an unwinding roll 51 for unwinding the polyimide film 1 on the upstream side in the conveyance direction of the polyimide film 1, and a polyimide film having a barrier layer and a copper sputter layer formed on the downstream side. A winding roll 52 for winding 1 is provided.

  Accordingly, the belt-shaped polyimide film 1 unwound from the unwinding roll 51 is transported along the outer peripheral wall surface of the rotary drum 50 with the width direction of the belt facing up and down, and the polyimide film 1 has a target. After the barrier layer is formed by 61, a copper sputter layer is formed by the target 62. Thus, after the barrier layer having a film thickness of 5 to 50 nm and the copper sputter layer having a film thickness of 20 to 400 nm are continuously formed in the sputtering apparatus 5, the polyimide film on which the barrier layer and the copper sputter layer are formed is formed. 1 is wound on a winding roll 52.

Next, this winding roll 52 is installed in a plating apparatus, and a copper plating layer is formed on the surface of the copper sputter layer.
Here, this plating apparatus carries in power supply means for supplying electricity to the barrier layer and the copper sputter layer of the polyimide film 1 and the polyimide film 1 with the band width direction directed in the vertical direction, and copper sulfate plating. It has a plurality of vertical electrolytic plating tanks for performing copper plating on the copper sputter layer by being immersed in the liquid, and the plurality of electrolytic plating tanks are arranged along the conveyance path of the polyimide film 1 Has been.

  Therefore, the polyimide film unwound from the winding roll 52 is immersed in a copper sulfate plating solution in a plurality of electrolytic plating tanks, and a copper plating layer is repeatedly formed on the surface of the copper sputtering layer. A copper layer of 5 to 10 μm is formed with the copper plating layer to obtain a copper-clad laminate. (End of metal layer formation process)

  Thus, as shown in FIG. 2, the copper clad laminated board obtained by the manufacturing method of this embodiment is provided with hydrophilicity by plasma treatment on one side of a polyimide film 1 having a film thickness of 20 to 50 μm. A coating layer 11 of a silane coupling agent having a thickness of 0.5 to 10 nm is formed. Further, a barrier layer (metal layer) 12 having a thickness of 5 to 50 nm, a copper sputter layer (metal layer) 13 having a thickness of 20 to 400 nm, and a copper plating layer (metal layer) 14 are sequentially laminated on the surface of the coating layer 11. The copper plating layer 14 is formed so as to be a copper layer having a film thickness of 5 to 10 μm together with the copper sputter layer 13.

  According to the method for producing a copper-clad laminate of this embodiment, the plasticizer added during film processing by vacuum drying the polyimide film 1 at a temperature of 60 ° C. or higher and 450 ° C. or lower by a vacuum drying step. In addition, the polyimide film 1 can be dried by evaporating the component derived from dimethylacetamide together with the adhering or penetrating moisture.

  Next, the polyimide film 1 after vacuum drying is subjected to a hydrophilic treatment by a plasma treatment process, and the film thickness after drying is 0.5% on the hydrophilicity imparting surface of the polyimide film 1 by a silane coupling agent coating process. By forming the coating layer 11 with a 10 nm silane coupling agent, the adhesion of the coating layer 11 to the polyimide film 1 can be enhanced.

  Furthermore, even when this copper-clad laminate is placed in a high-temperature atmosphere, the components such as water and plasticizer are evaporated from the polyimide film 1 by the vacuum drying step, so that these components penetrate into the copper layer. Thus, the formation of copper oxide can be effectively prevented, and the decrease in heat-resistant peel strength can be suppressed.

  In addition, this invention is not limited to the above-mentioned embodiment at all, For example, you may plasma-treat on both surfaces of the polyimide film 1, and may form the coating layer 11 of a silane coupling agent.

Next, examples will be described.
[Example]
According to the above-mentioned method, the copper-clad laminates of Examples 1 to 9 were obtained under the conditions shown in Table 1.
For the copper-clad laminates of Examples 1 to 8, first, the polyimide film 1 having a film thickness of 38 μm was vacuum-dried at 1 × 10 ⁻² Torr for 1 hour in the vacuum drying process, and then the polyimide film 1 of the plasma treatment process was processed. A hydrophilic treatment is applied to one surface by plasma, and then a silane coupling agent is applied to the hydrophilic surface of the polyimide film 1 in a silane coupling agent application step and dried at room temperature, thereby providing a coating layer having a thickness of 2 nm. 11 was formed.

  Next, in the metal layer forming step, a barrier layer 12 made of nickel and chromium having a film thickness of 25 nm and a copper sputter layer 13 having a film thickness of 200 nm are formed on the coating layer 11 using a sputtering apparatus. It was obtained by forming a copper plating layer 14 having a thickness of 8 μm on the surface of the layer 13.

  About the copper clad laminated board of Example 9, except having not the said plasma treatment process, the coating layer 11 is formed on the conditions shown in Table 1 similarly to Examples 1-8, and a coating layer is formed in a metal layer formation process. 11, a 25 nm thick nickel and chromium barrier layer 12 and a 200 nm thick copper sputtered layer 13 are formed using a sputtering apparatus, and then the surface of the copper sputtered layer 13 is plated with 8 μm thick copper. Obtained by forming layer 14.

  In addition, the hydrophilic treatment by plasma uses a linear ion source (a plasma treatment apparatus manufactured by Advanced Energy) for all of the copper-clad laminates of Examples 1 to 9, and the flow rate of Ar is 4.5 sccm, The voltage was set to 2000v. Further, SIC2296.2 (product name (manufactured by Amax Co., Ltd.)) is used as the chloromethyl group-containing silane coupling agent, and IS-1000 (product name (Nikko Metal Co., Ltd.) is used as the imidazole group-containing silane coupling agent. Manufactured)).

  The normal peel strength of the copper-clad laminates of Examples 1 to 9 thus obtained and the heat-resistant peel strength after being kept at a high temperature of 150 ° C. for 500 hours were measured according to JIS C5016, respectively, and are shown in Table 1.

[Comparative example]
In the same manner as in Examples 1 to 8, copper-clad laminates of Comparative Examples 1 to 4 were obtained under the conditions shown in Table 2. Regarding the copper-clad laminates of Comparative Examples 1 to 4, first, a polyimide film 1 having a film thickness of 38 μm was vacuum-dried at 1 × 10 ⁻² Torr for 1 hour in a vacuum drying process, and then a polyimide film in a plasma treatment process. A hydrophilic treatment is performed on one surface of 1 by plasma, and then a silane coupling agent is applied to the hydrophilic surface of the polyimide film 1 in a silane coupling agent coating step, followed by drying at room temperature. The coating layer 11 was formed.

Next, in the metal layer forming step, a barrier layer 12 made of nickel and chromium having a film thickness of 25 nm and a copper sputter layer 13 having a film thickness of 200 nm are formed on the coating layer 11 using a sputtering apparatus. It was obtained by forming a copper plating layer 14 having a thickness of 8 μm on the surface of the layer 13.
The hydrophilic treatment with plasma was performed for all of the copper-clad laminates of Comparative Examples 1 to 4 with an Ar flow rate of 4.5 sccm and a voltage of 2000 v.
Further, SIC2296.2 (product name (manufactured by Amax Co., Ltd.)) is used as the chloromethyl group-containing silane coupling agent, and IS-1000 (product name (Nikko Metal Co., Ltd.) is used as the imidazole group-containing silane coupling agent. Manufactured)).

  The normal peel strength of the copper-clad laminates of Comparative Examples 1 to 4 thus obtained and the heat-resistant peel strength after being kept at a high temperature at 150 ° C. for 500 hours were measured according to JIS C5016, and are shown in Table 2.

Next, except for not having the silane coupling agent coating step, the copper-clad of Comparative Example 5 having the same vacuum drying step, plasma treatment step, and metal layer forming step as those of Comparative Examples 1 to 4 under the conditions shown in Table 3 A laminate and a copper-clad laminate of Comparative Example 6 having no plasma treatment step were obtained.
And the normal-state peel strength of the copper clad laminated board of Comparative Examples 5-6 and the heat-resistant peel strength after hold | maintaining high temperature at 150 degreeC for 500 hours were measured according to JISC5016, respectively, and were shown in Table 3.

As can be seen from Tables 1 to 3, the copper-clad laminates of Examples 1 to 9 are both relatively high in normal peel strength and heat-resistant peel strength, and also have a heat-resistant peel strength that means a decrease in adhesion after holding at high temperatures. The decrease from the normal peel strength is very small, and the decrease in the heat-resistant peel strength can be suppressed, which is suitable for the production of printed wiring boards.
On the other hand, the copper-clad laminates of Comparative Examples 1 to 6 all have low heat-resistant peel strength, and in particular, in the case of Comparative Examples 1 and 2 in which normal peel strength of 600 N / m or more was obtained, heat resistance was also obtained. The peel strength has decreased significantly.

It is a cross-sectional schematic diagram of the sputtering device 5 used when manufacturing a flexible base material. It is a cross-sectional schematic diagram of the copper clad laminated board obtained by the manufacturing method of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polyimide film 5 Magnetron sputter apparatus 11 Coating layer of silane coupling agent 12 Barrier layer 13 Copper sputter layer 14 Copper plating layer 50 Rotating drum 51 Unwinding roll 52 Winding roll 55 Bulkhead member 61 Barrier layer target 62 For copper sputtered layer target

Claims (4)

  After the polyimide film is vacuum dried at a temperature of 60 ° C. or higher and 450 ° C. or lower, a silane coupling agent is applied to at least one surface of the polyimide film, and then a metal is applied to the surface of the coating layer of the silane coupling agent. The manufacturing method of the flexible base material characterized by forming a layer.   The method for producing a flexible substrate according to claim 1, wherein hydrophilicity is imparted to the surface of the polyimide film to which the silane coupling agent is applied by plasma treatment. The method for producing a flexible base material according to claim 1 or 2, wherein the polyimide film is vacuum-dried at 1 x ^10-2 Torr or less. A flexible substrate obtained using the method for producing a flexible substrate according to any one of claims 1 to 3,
A flexible base material, wherein a coating layer of the silane coupling agent and the metal layer are sequentially laminated on the polyimide film, and the silane coupling agent contains a chloromethyl group or an imidazole group. .

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