JP2011190496A - Method of manufacturing laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate that prevents layers between a polyimide substrate and a conductive film layer from peeling. <P>SOLUTION: The method of manufacturing a laminate sequentially includes: an alkali treatment step in which an alkali-treated layer is formed on the surface of the polyimide substrate 2 by bringing the surface of the substrate 2 into contact with an alkaline aqueous solution; a catalyst-applying step in which the alkali-treated layer is brought into contact with an aqueous solution containing a metal catalyst to apply the metal catalyst to the alkali-treated layer; a reduction step in which the alkali-treated layer to which the metal catalyst is applied is brought into contact with a reduction treatment solution to reduce the metal catalyst to which the alkali-treated layer is applied to form a surface-treated layer 3; a seed-layer forming step in which a seed layer 4 containing nickel is laminated on the surface-treated layer; a metal-layer forming step in which a metal layer 6 is laminated on the seed layer 4; and a heat-treatment step in which the substrate on which the seed layer 4 and the metal layer 6 are formed is treated with heat in the atmosphere. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a laminate having a polyimide substrate and a metal layer formed on the polyimide substrate.

  The flexible metal laminated board is mainly used as a base material for a printed wiring board having flexibility. In recent years, the trend toward miniaturization and higher density of electronic devices using printed wiring boards has been accelerated, and the demand for fine pitch and high dielectric properties of printed wiring boards has increased. Therefore, development of a flexible metal laminate having a two-layer structure including a base material and a metal layer and using no adhesive has been actively promoted.

  The manufacturing method of these flexible metal layer laminates includes an alkali treatment step of forming an alkali treatment layer on the surface of the polyimide substrate by bringing the surface of the polyimide substrate into contact with an alkaline aqueous solution, and then the alkali treatment layer with a metal catalyst. A catalyst application step of bringing the metal composition into contact with an aqueous solution containing the catalyst, and then applying the alkali treatment layer to which the metal catalyst has been applied to the reduction treatment solution to be applied to the alkali treatment layer. A reduction step of forming a first surface treatment layer by reducing the metal catalyst, a seed layer formation step of laminating a seed layer on the surface treatment layer, and a metal layer on the seed layer And a metal layer forming step for laminating a laminate, and a method for producing a laminate (for example, a technique similar to this is disclosed in the following Patent Document It has been described in).

International Publication No. 2009/004774

  The problem with the conventional example is that, in the process of forming printed wiring, which is a process after manufacturing these laminates, the resist removing remover used permeates between the polyimide substrate and the seed layer, The layer was to dissolve. That is, in the above conventional example, the adhesion strength between the polyimide substrate and the seed layer of the laminated board after forming the printed wiring is weak due to melting by the resist removing remover used in the process of forming the printed wiring. It was.

  Therefore, an object of the present invention is to increase the adhesion strength between a polyimide substrate and a seed layer of a laminated board after forming a printed wiring.

  In order to achieve this object, the present invention provides a surface treatment process for forming a surface treatment layer by performing a surface treatment on a polyimide substrate, and then a seed for laminating a seed layer containing nickel on the surface treatment layer. A layer forming step, a metal layer forming step of laminating a metal layer on the seed layer, and then a heat treatment step of heat-treating the polyimide substrate on which the seed layer and the metal layer are formed in the atmosphere. The manufacturing method of the laminated board which consists of these.

  This achieves the intended purpose.

  As described above, according to the present invention, the adhesion strength between the polyimide substrate and the seed layer of the laminated board after the formation of the printed wiring can be increased by performing the heat treatment in the air after forming the seed layer on the polyimide substrate. .

  That is, in the present invention, an oxide film is formed on the surface of the seed layer by performing a heat treatment in the air after forming the seed layer on the polyimide substrate, so that the oxide film is produced after the laminate is manufactured. Since the removal agent for removing the resist used in the process of forming the printed wiring, which is the process, could be reduced between the polyimide substrate and the seed layer, the printed wiring was formed as a result. The adhesion strength between the polyimide substrate and the seed layer of the laminated board later can be increased.

Sectional drawing which shows the structure of the laminated board which concerns on one Embodiment of this invention. The flowchart which shows the flow of the manufacturing method of the laminated board which concerns on one Embodiment of this invention. The flowchart which shows the detail of the surface treatment process of FIG. FIG. 4A is a view showing a photograph taken from the upper surface after penetrating a laminated board for 5 minutes in the same sodium hydroxide aqueous solution (concentration 5%, temperature 55 ° C.) as a resist removing agent. FIG. 4B is a view showing the case of using nickel phosphorus as a seed layer and no heat treatment after forming a metal layer. FIG. 4B is a comparative example (using nickel phosphorus as a seed layer and forming 275 in a nitrogen atmosphere after forming the metal layer). FIG. 4C shows an embodiment of the present invention (using nickel phosphorus as a seed layer and performing heat treatment at 275 ° C. in the air after forming the metal layer). Illustration showing the case FIG. 5 (a) shows a photograph taken from the upper surface after the laminated plate has been immersed in the same sodium hydroxide aqueous solution (concentration 5%, temperature 55 ° C.) for 5 minutes after removing the resist from the resist. FIG. 5B is a diagram showing a heat treatment performed at 250 ° C. in the air after formation, FIG. 5B is a diagram showing a heat treatment performed at 275 ° C. in the air after forming a metal layer, and FIG. ) Is a diagram showing a heat treatment performed at 300 ° C. in the air after forming the metal layer.

  The embodiments described below do not limit the present invention.

[1] First Embodiment [Configuration of Laminate]
FIG. 1 is a cross-sectional view showing the configuration of the laminated plate 1 of the present embodiment.

  As shown in FIG. 1, the laminate 1 includes a polyimide substrate 2, a surface treatment layer 3 formed on the surface of the polyimide substrate 2, a seed layer 4 formed on the surface treatment layer 3, and side surfaces of the seed layer 4. And the metal layer 6 formed on the oxide layer 5.

  The configuration of the polyimide substrate 2 is not particularly limited, and for example, a commercially available substrate can be used as the polyimide substrate 2. Examples of commercially available substrates include Kapton 150EN-C, a polyimide film manufactured by Toray DuPont, Upilex manufactured by Ube Industries, Apical manufactured by Kaneka Chemical, and the like.

  The surface treatment layer 3 is formed by treating the surface of the polyimide substrate 2 with an alkaline aqueous solution, applying a metal catalyst, and further performing a reduction treatment.

  Moreover, the material which comprises the seed layer 4 should just be a material excellent in adhesiveness with a polyimide resin compared with the material which comprises the metal layer 6. FIG. Moreover, as a material, a substance with low electrical resistance is preferably used. For example, when the metal layer 6 is made of copper (Cu), examples of the material of the seed layer 4 include nickel phosphorus (Ni—P), copper nickel phosphorus (Cu—Ni—P), and the like. Alloys containing are preferred.

  The seed layer 4 is not limited to a single layer, and may comprise a plurality of layers such as two layers of nickel phosphorus / copper nickel phosphorus.

  The oxide layer 5 is formed by performing heat treatment in the atmosphere after the metal layer 6 is formed. Details of this heat treatment will be described below.

  Moreover, as a material of the metal layer 6, a substance with low electrical resistance, such as copper, is preferably used.

[2] Method for Manufacturing Laminated Plate FIG. 2 is a flowchart showing an example of a method for manufacturing the laminated plate 1.

(Step S21: Pretreatment process)
As shown in FIG. 2, the polyimide substrate 1 can be pretreated (step S21). By this pretreatment, foreign matters and oils adhering to the surface of the polyimide substrate 1 are removed. As the pretreatment, for example, degreasing can be performed.

  This pretreatment step is not an essential step in the present invention, and is not necessary if the surface of the polyimide substrate 2 is clean.

(Step S22: Surface treatment process)
Next, the surface treatment of the polyimide substrate 2 is performed (step S22).

  The details of the surface treatment process will be described with reference to FIG.

  As shown in FIG. 3, first, the surface of the polyimide substrate 2 is brought into contact with an alkaline aqueous solution (alkali treatment step: step S221). By this alkali treatment step, the imide ring on the surface of the polyimide substrate 2 is alkali-hydrolyzed to generate carboxylic acid. Thus, an alkali treatment layer is formed on the surface of the polyimide substrate 2.

Thereafter, the alkali treatment layer of the polyimide substrate 2 is brought into contact with an aqueous solution containing a metal catalyst (step S222: catalyst application step). As this metal catalyst, any catalyst can be used as long as it can be a catalyst for forming the seed layer 4, but a palladium catalyst is particularly preferably used.
Various conditions such as the concentration of the catalyst, the treatment time, and the temperature in the catalyst application step can be appropriately changed. Thus, the catalyst is bonded to the alkali treatment layer.

  Furthermore, the polyimide substrate 2 is brought into contact with a reducing agent that reduces the metal catalyst applied to the alkali treatment layer on the surface of the polyimide substrate 2 (step S223: reduction step). Specifically, the polyimide substrate 2 is brought into contact with an aqueous solution (reduction treatment solution) containing a reducing agent. By the reduction step, the catalyst applied to the alkali treatment layer is reduced. Various conditions such as the concentration of the reducing agent, the treatment time, and the temperature in the reduction treatment solution can be appropriately changed.

  The surface treatment layer 3 is formed by the above surface treatment process.

  The surface treatment process is not limited to the configuration shown in FIG. 3, and may be a process including only the alkali treatment process (step S221).

(Step S23: Seed layer forming step)
As shown in FIG. 2, the seed layer 4 is formed by performing a seed layer formation process after the surface treatment process. As a material for the seed layer 4, for example, a metal, particularly an alloy containing nickel (particularly nickel phosphorus (Ni—P)) is preferably used. As a method for forming the seed layer 4, a wet plating method (for example, electroless plating method), a sputtering method, or the like is preferably used.

(Step S24: Metal layer forming step)
As shown in FIG. 2, a metal layer stacking step is then performed to form the metal layer 6. As described above, a metal such as copper is used as the material of the metal layer 6. As a method for forming the metal layer 6, for example, an electrolytic plating method or the like is used.

(Step S25: Heat treatment step)
As shown in FIG. 2, an oxide layer 5 is formed on the side surface of the seed layer 4 by performing a heat treatment process next. The heat treatment process is performed by heating the polyimide substrate 2 that has undergone step S24, and specifically, is performed by placing it in the atmosphere such as a temperature bath. The heat treatment temperature in the heat treatment step is preferably 250 ° C. or higher and 300 ° C. or lower, particularly preferably about 275 ° C. This heat treatment temperature will be described in detail later. In addition, this processing time can be appropriately changed according to conditions such as temperature. By performing this heat treatment step, the oxide layer 5 is formed on the side surface of the seed layer 4.

  The oxide layer 5 formed in this way has excellent corrosion resistance (particularly acid chemicals). Therefore, after the metal layer forming step described later, the resist removing remover used in the step of forming the printed wiring (post-processing step) is more specifically between the polyimide substrate 2 and the seed layer 4. Intrusion between the surface treatment layer 3 and the seed layer 4 is reduced. As a result, it is possible to improve the decrease in the adhesion strength of the seed layer 4 in the post-processing step.

[3] Other Embodiments In the first embodiment, the step of forming the seed layer 4 made of an alloy containing nickel includes a seed layer step of laminating the seed layer material, and then oxidizing the surface by heat-treating the material. A heat treatment step of forming the layer 5. However, the formation process of the seed layer 4 is not limited to this.

For example, it is possible to separately form the oxide layer 5 by using the sputtering method, and the seed layer 4 is formed by using the sputtering method, and then heat treatment is performed in an oxygen atmosphere inside the vacuum apparatus. It is also possible to form the oxide layer 5 by performing.
[4] Comparison of One Embodiment of the Present Invention with Conventional Example and Effects of Invention Next, a comparison between one embodiment of the present invention and a conventional example will be described.

  FIG. 4 is a view showing a photograph taken from the upper surface after penetrating the laminated plate in the same sodium hydroxide aqueous solution (concentration 5%, temperature 55 ° C.) for 5 minutes after removing the resist from the resist. ) Is a conventional example (using nickel phosphorus as a seed layer and no heat treatment after formation of the seed layer), and FIG. 4B is a comparative example (using nickel phosphorus as the seed layer and forming a metal layer in a nitrogen atmosphere). 4 (c) shows an embodiment of the present invention (using nickel phosphorus as a seed layer and performing heat treatment at 275 ° C. in the air after forming the metal layer). .

As shown in FIGS. 4A and 4B, in the example (no heat treatment) and the comparative example (heat treatment in a nitrogen atmosphere), the metal layer 6 has black lines (FIGS. 4A and 4B). A) inside is observed. This black line is a phenomenon observed because the same aqueous solution (sodium hydroxide) as the resist removing remover used in the process of forming the printed wiring permeates between the polyimide substrate and the seed layer.
On the other hand, as shown in FIG. 4C, in one embodiment (heat treatment in the atmosphere) of the present invention, the black line is not observed in the metal layer 6.
Actually, when the adhesion strength after penetration for 5 minutes in the same sodium hydroxide aqueous solution (concentration 5%, temperature 55 ° C.) as the removal agent for resist removal was measured for the laminated plate, FIG. 4 (a) (no heat treatment) 0.25 [N / mm] in the case of FIG. 4, 0.27 [N / mm] in the case of FIG. 4B (heat treatment in nitrogen atmosphere), and 0.44 in the case of FIG. 4C (heat treatment in air). [N / mm].

  That is, in the case of the conventional example (without heat treatment) and the comparative example (heat treatment in a nitrogen atmosphere), a significant decrease in adhesion strength was observed. In one embodiment of the present invention, No decrease was observed, and it was confirmed that the adhesive strength was sufficiently large (0.4 [N / mm]) for practical use. 4 (a), 4 (b), and 4 (c), the adhesion strength immediately after the formation of the metal layer 6 shows a numerical value of 0.4 [N / mm] or more, which is practical. It was confirmed that the adhesive strength was sufficient before penetration into the same sodium hydroxide aqueous solution (concentration 5%, temperature 55 ° C.) as the removal agent for resist removal.

  Based on the above results, this laminate was manufactured by forming an oxide layer 5 on the side surface of the seed layer 4 (oxidizing the side surface of the seed layer 4) by performing heat treatment in the air after forming the metal layer. It is possible to reduce the permeation between the polyimide substrate and the seed layer of the removal agent for removing the resist used in the subsequent step of forming the printed wiring.

As a result, the adhesion strength between the polyimide substrate and the seed layer of the laminated board after the formation of the printed wiring can be increased.
[5] Heat treatment temperature in heat treatment step Next, the heat treatment temperature in the heat treatment step will be described.

FIG. 5 is a view showing a photograph taken from the upper surface after penetrating the laminated plate for 5 minutes in the same sodium hydroxide aqueous solution (concentration 5%, temperature 55 ° C.) as the resist removing agent. ) Is heat-treated at 250 ° C. in the air after forming the metal layer, FIG. 5B is heat-treated at 275 ° C. in the air after forming the metal layer, and FIG. It shows what heat-processed at 300 degreeC in air | atmosphere after metal layer formation.
As shown in FIG. 5A, when the heat treatment temperature in the atmosphere is 250 ° C., a black line as described in [4] above is observed (corresponding to A in FIG. 5A). . However, it can be seen that the black line is much thinner than in FIG. That is, it can be seen that although the same aqueous solution (sodium hydroxide) for removing the resist permeates between the polyimide substrate and the seed layer, the degree is improved. Further, the adhesion strength after 5 minutes of penetration into the same sodium hydroxide aqueous solution (concentration 5%, temperature 55 ° C.) as a resist removing agent was 0.42 [N / mm]. Has confirmed that the adhesive strength was sufficient.

  However, when the heat treatment after forming the metal layer is performed in the atmosphere at a temperature lower than 250 ° C. (for example, 180 ° C.), the same sodium hydroxide aqueous solution (concentration 5%, temperature 55 ° C.) as the removal agent for resist removal. ), The adhesion strength after penetration for 5 minutes was measured and showed a low value of 0.32 [N / mm] or less, and it was not possible to obtain sufficient adhesion strength for practical use.

  From the above results, when the heat treatment temperature in the atmosphere after forming the seed layer is less than 250 ° C., the formation of the oxide film 5 is insufficient, so the same aqueous solution (sodium hydroxide) for removing the resist is polyimide. It can be seen that the penetration between the substrate and the seed layer cannot be improved.

  That is, it is understood that the heat treatment temperature in the air after forming the metal layer must be 250 ° C. or higher.

  Further, as shown in FIG. 5 (c), even when the heat treatment temperature in the atmosphere is 300 ° C., a black line as described in [4] above is observed (A in FIG. 5 (a)). Equivalent). However, it can be seen that the black line is much thinner than in FIG. That is, it can be seen that although the same aqueous solution (sodium hydroxide) for removing the resist permeates between the polyimide substrate and the seed layer, the degree is improved. Furthermore, the adhesion strength after 5 minutes of penetration into the same sodium hydroxide aqueous solution (concentration 5%, temperature 55 ° C.) as a resist removing agent was 0.43 [N / mm]. Has confirmed that the adhesive strength was sufficient.

However, when the heat treatment after the metal layer is formed at a temperature higher than 300 ° C. (eg, 320 ° C. or higher) in the atmosphere, the adhesion strength immediately after the metal layer is formed is 0.33 [N / mm]. The numerical value of less than was shown, and sufficient adhesion strength for practical use could not be obtained.
From the above results, when the heat treatment temperature in the air after forming the metal layer is performed at a temperature higher than 300 ° C., the oxide film 5 becomes too thick so that the adhesion between the metal layer and the seed layer is increased. It turns out that intensity falls.

That is, it is understood that the heat treatment temperature in the air after forming the metal layer must be 300 ° C. or less.
Based on the above results, an oxide layer is formed on the surface of the metal layer by performing heat treatment at a heat treatment temperature of 250 ° C. or higher and 300 ° C. or lower in the air after forming the metal layer (the side surface of the seed layer is oxidized). Reducing the permeation of the resist removal remover used between the polyimide substrate and the seed layer in the process of forming the printed wiring, which is the process after manufacturing the laminated board. I can say that.

  As a result, it is possible to improve the decrease in the adhesion strength between the polyimide substrate and the seed layer of the laminated board after the formation of the printed wiring.

  According to the method for manufacturing a laminated board of the present invention, it is possible to provide a laminated board in which the decrease in the adhesion strength between the polyimide substrate and the seed layer of the laminated board after forming the printed wiring is improved. In particular, it is useful as a laminated plate for electrical connection parts inside equipment that has a moving part such as a mobile phone and parts installation space such as a flat-screen TV.

DESCRIPTION OF SYMBOLS 1 Laminated board 2 Polyimide substrate 3 Surface treatment layer 4 Seed layer 5 Oxidation layer 6 Metal layer

Claims (2)

An alkali treatment step of forming an alkali treatment layer on the polyimide substrate surface by contacting the surface of the polyimide substrate with an alkaline aqueous solution;
Thereafter, the alkali treatment layer is brought into contact with an aqueous solution containing a metal catalyst, and a catalyst application step of applying a metal catalyst to the alkali treatment layer;
Thereafter, the alkali treatment layer provided with the metal catalyst is brought into contact with a reduction treatment solution, and the metal catalyst applied to the alkali treatment layer is reduced to form a surface treatment layer; and
Thereafter, a seed layer forming step of laminating a seed layer containing nickel on the surface treatment layer, and then a metal layer forming step of laminating a metal layer on the seed layer,
Thereafter, a heat treatment step of performing heat treatment in the atmosphere on the polyimide substrate on which the seed layer and the metal layer are formed,
The manufacturing method of the laminated board which consists of.   The method for manufacturing a laminated board according to claim 1, wherein a heat treatment temperature in the heat treatment step is 250 ° C. or more and 300 ° C. or less.

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