JP2011202222A - Laminate and method for producing the laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate which enhances peeling strength between a polyimide substrate and seed layers.SOLUTION: The laminate 1 includes: the polyimide substrate 2; metal-containing surface-treated layers 3 which are formed by surface-treating both surfaces of the substrate 2 with an alkali aqueous solution, applying a metal catalyst to the surface-treated part, and reducing the catalyst; seed layers 4 which are formed on the surface-treated layers; and metal layers 5 which are formed on the seed layers. Film thicknesses of the seed layers 4 are between 70 nm and 100 nm, resulting to enhance the peeling strength between the polyimide substrate 2 and seed layers 4.

Description

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

  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.

  These flexible metal layer laminates are obtained by surface-treating a polyimide substrate and the polyimide substrate with an alkaline aqueous solution, then applying a metal catalyst to the surface-treated portion, and then reducing the metal catalyst. A laminate comprising a surface treatment layer containing metal, a seed layer formed on the surface treatment layer by an electroless plating method, and a metal layer formed on the seed layer. (For example, a similar technique is described in Patent Document 1 below).

  Further, in recent years, there has been a demand for higher wiring density of printed wiring boards, and there has been a demand for flexible metal laminates in which metal layers are laminated on both sides instead of one side of a substrate.

International Publication No. 2009/004774

The problem with the conventional example is that the polyimide substrate is treated with an alkaline aqueous solution, so that the moisture content inside the polyimide substrate is increased, and a film of a seed layer / metal layer is laminated on both sides of the polyimide substrate. Since the moisture content did not decrease, the adhesion strength between the polyimide substrate and the seed layer was weak after the seed layer / metal layer was formed. (Note that in the case where the seed layer / metal layer is formed only on one side of the polyimide substrate, the content of moisture in the polyimide substrate increases immediately after the treatment by the treatment with the alkaline aqueous solution. (This moisture spontaneously evaporates from the surface where the metal layer is not formed, so the adhesion strength between the polyimide substrate and the seed layer was strong.)
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.

  And in order to achieve this object, the present invention surface-treats the polyimide substrate and both surfaces of the polyimide substrate with an alkaline aqueous solution, and then gives a metal catalyst to the surface-treated portion, and then the metal A surface treatment layer containing metal formed by reducing the catalyst, a seed layer formed on the surface treatment layer, and a metal layer formed on the seed layer, A laminate having a seed layer thickness of 70 nm to 100 nm was obtained.

  The present invention also provides an alkali treatment step of forming an alkali treatment layer on the polyimide substrate surface by bringing the surface of the polyimide substrate into contact with an alkaline aqueous solution, and then bringing the alkali treatment layer into contact with an aqueous solution containing a metal catalyst. A catalyst applying step for applying a metal catalyst to the alkali-treated layer, and then contacting the alkali-treated layer provided with the metal catalyst with a reduction treatment solution to reduce the metal catalyst applied to the alkali-treated layer. A reduction step for forming a surface treatment layer, a seed layer formation step for laminating a seed layer containing nickel on the surface treatment layer, a drying step for removing moisture inside the polyimide substrate, and the heat treatment. And a metal layer forming step of laminating a metal layer on the seed layer, and a method for producing a laminated board.

  This achieves the intended purpose.

  As described above, the present invention can increase the adhesion strength between the polyimide substrate and the seed layer by setting the film thickness of the seed layer to 70 nm or more and 100 nm or less.

  That is, in the present invention, by setting the film thickness of the seed layer to 70 nm or more and 100 nm or less, the moisture content in the polyimide substrate can be greatly reduced by performing the drying process immediately after the formation of the seed layer. As a result, the adhesion strength between the polyimide substrate of the laminated plate and the seed layer 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 figure which shows the result of having measured the dehydration amount of the moisture with the thermogravimetry apparatus corresponding to the humidity atmosphere of the polyimide substrate before processing (initial state) The figure which shows the result of having measured the dehydration amount of the water | moisture content by the thermogravimetry apparatus corresponding to the humidity atmosphere of the polyimide substrate after surface-treating with alkaline aqueous solution The figure which shows the result of having measured the dehydration amount of the water | moisture content by the thermogravimetry apparatus corresponding to the humidity atmosphere of the polyimide substrate after forming 70 [nm] of nickel phosphorus as a seed layer after forming a surface treatment layer on both surfaces of a polyimide substrate The figure which shows the result of having measured the dehydration amount of the water | moisture content by the thermogravimetry apparatus corresponding to the humidity atmosphere of the polyimide substrate after forming 100 [nm] of nickel phosphorus as a seed layer after forming a surface treatment layer on both surfaces of a polyimide substrate The figure which shows the result of having measured the dehydration amount of the moisture by the thermogravimetry apparatus corresponding to the humidity atmosphere of the polyimide board after forming nickel phosphorus 150 [nm] as a seed layer after forming a surface treatment layer on both sides of a polyimide board

  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 laminated board 1 surface-treats the polyimide substrate 2 and both surfaces of the polyimide substrate with an alkaline aqueous solution, and then gives a metal catalyst to the surface-treated portion, and then A metal-containing surface treatment layer 3 formed by reducing a metal catalyst; a seed layer 4 formed on the surface treatment layer; and a metal layer 5 formed on the seed layer. is doing. Here, the film thickness of the seed layer 4 is 70 nm or more and 100 nm or less.

  By doing so, moisture inside the polyimide substrate can be removed by performing a drying process immediately after the formation of the seed layer. As a result, the adhesion strength between the polyimide substrate and the seed layer of the laminate is increased. be able to. These will be described in detail later.

  Moreover, the structure of the polyimide substrate 2 is not specifically limited, As the polyimide substrate 2, a commercially available board | substrate can be used, for example. 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 5. 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.

  Moreover, as a material of the metal layer 5, 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 S1: Pretreatment process)
As shown in FIG. 2, the polyimide substrate 1 can be pretreated (step S1). 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 S2: Alkali treatment process)
Next, the alkali surface treatment of the polyimide substrate 2 is performed (step S2).

  In this step, the surface of the polyimide substrate 2 is brought into contact with an alkaline aqueous solution. 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 (not shown) is formed on the surface of the polyimide substrate 2.

(Step S3: catalyst application step)
Next, the alkali treatment layer of the polyimide substrate 2 is brought into contact with an aqueous solution containing a metal catalyst (step S3). 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.

(Step S4: Reduction process)
Next, it is made to contact with the reducing agent which reduces the metal catalyst provided to the alkali treatment layer of the surface of the polyimide substrate 2 (step S4). Specifically, the polyimide substrate 2 is brought into contact with an aqueous solution (reduction treatment solution) containing a reducing agent. In the reduction step, the catalyst applied to the alkali treatment layer is reduced, and a metal is formed.
This metal depends on the aforementioned catalyst, but when a palladium catalyst is used, palladium is formed. Various conditions such as the concentration of the reducing agent, the treatment time, and the temperature in the reduction treatment solution can be changed as appropriate.

  As described above, the surface treatment layer 3 is formed by performing the alkali treatment step (step S2), the catalyst application step (step S3), and the reduction step (step S4).

(Step S5: Seed layer forming step)
Next, after the surface treatment process, a seed layer forming process is performed to form the seed layer 4 (step S5). 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. The seed layer 4 is formed using an electroless plating method. Here, the film thickness of the seed layer 4 needs to be not less than 70 nm and not more than 100 nm, but in this embodiment, 100 nm is used. These will be described in detail later.

(Step S6: drying process)
As shown in FIG. 2, the moisture in the polyimide substrate is removed by performing a drying process next (step S6). A drying process is performed by heating the polyimide substrate 2 which passed through step S25, and specifically, it is performed by putting in air | atmosphere, such as a temperature tank.
Here, the drying temperature in the drying process needs to be 100 ° C. or higher in order to remove moisture, but in this embodiment, 150 ° C. is used.
Further, this processing time can be appropriately changed according to conditions such as temperature, but in this embodiment, it was performed for 5 minutes.

(Step 7: Metal layer forming process)
Finally, a metal layer stacking process is performed to form the metal layer 5 (step S7). As described above, a metal such as copper is used as the material of the metal layer 5. As a method for forming the metal layer 6, for example, an electrolytic plating method or the like is used.

As described above, the laminate of this embodiment can be manufactured.
[2] Effects of Invention in One Embodiment of the Present Invention Next, effects of the invention of one embodiment of the present invention will be described.

  3-7 is a figure which shows the result of having measured the dehydration amount of the water | moisture content from a to-be-measured object in the thermogravimetric measuring apparatus (Bruker AXS Co., Ltd. TG2000SA) corresponding to humidity atmosphere. 3 is a polyimide substrate before treatment (initial state), FIG. 4 is a polyimide substrate after surface treatment with an alkaline aqueous solution (after S2 in FIG. 2 described above), and FIG. 5 is a surface treatment layer on both surfaces of the polyimide substrate. FIG. 6 shows a polyimide substrate after forming nickel phosphorous as a seed layer after forming a surface treatment layer on both surfaces of the polyimide substrate, and FIG. These are figures which show the result of having measured the polyimide substrate after forming nickel phosphorus 150 [nm] as a seed layer after forming a surface treatment layer on both surfaces of a polyimide substrate.

  This humidity-gravity thermogravimetric measuring apparatus is for measuring a change in the weight of an object to be measured while placing the object to be measured on the apparatus and applying heat to the object to be measured. 3 to 7, the object to be measured is set to an initial temperature of 100 ° C., the temperature is increased to 200 ° C. in 5 minutes, the change in the weight of the object to be measured in the 5 minutes is measured, and the measurement is started (initial). The weight change rate of the last measured object (after 5 minutes) with respect to the weight of the measured object was defined as the amount of water dehydrated of each measured object. 3 to 7, the horizontal axis represents time (when heat is applied), and the horizontal axis represents the weight change rate of the object to be measured.

  Here, as shown in FIGS. 3 and 4, the amount of water dehydrated from the polyimide substrate before the treatment (initial state) is 0.48% (shown in FIG. 3), and the polyimide after the surface treatment with an alkaline aqueous solution. The amount of water dehydrated from the substrate is 1.30% (shown in FIG. 4), which indicates that the amount of water dehydrated from the polyimide substrate after the surface treatment with an alkaline aqueous solution is large. Since the amount of dehydration depends on the amount of water contained in the polyimide substrate, it can be seen from these results that the moisture content inside the polyimide substrate is increased by treating the polyimide substrate with an alkaline aqueous solution. That is, the increase in the moisture content caused by treating the polyimide substrate with an alkaline aqueous solution causes the adhesion strength between the polyimide substrate and the seed layer to become weaker after the seed layer / metal layer is formed.

  Further, as shown in FIGS. 5 and 6, after the surface treatment layer is formed on both sides of the polyimide substrate, the dehydration amount of water from the polyimide substrate after forming 70 [nm] of nickel phosphorus as a seed layer is 0.68% (see FIG. 5). 5), after the surface treatment layer is formed on both sides of the polyimide substrate, the amount of water dehydrated from the polyimide substrate after forming 100 [nm] of nickel phosphorus as a seed layer is 0.33% (shown in FIG. 6). Yes. That is, in these cases, it is understood that the moisture content in the polyimide substrate is reduced by performing the above-described drying step (corresponding to S6 in FIG. 2) after forming the seed layer.

  However, as shown in FIG. 7, after the surface treatment layers are formed on both sides of the polyimide substrate, the amount of water dehydrated from the polyimide substrate after forming 150 [nm] of nickel phosphorus as a seed layer is 0% (shown in FIG. 7). It can be seen that there is no dehydration. From this result, if nickel phosphorous is formed in a thickness of 150 [nm] or more as a seed layer after forming the surface treatment layer on both surfaces of the polyimide substrate, the above-described drying step (corresponding to S6 in FIG. 2) was performed after the formation. However, it turns out that the water | moisture content inside the polyimide board | substrate which causes the adhesive strength of this polyimide board | substrate and a seed layer to become weak cannot be removed.

  Actually, after forming a surface treatment layer on both sides of the polyimide substrate and forming 70 [nm] of nickel phosphorous as a seed layer, the above-described drying process (corresponding to S6 in FIG. 2) is performed. When the adhesion strength with the seed layer was measured, the adhesion strength showed 0.45 [N / mm]. After forming the surface treatment layer on both sides of the polyimide substrate and forming 100 [nm] of nickel phosphorus as a seed layer, The drying step (corresponding to S6 in FIG. 2) was performed, and then the adhesion strength between the polyimide substrate and the seed layer after standing for 1 week was measured. The adhesion strength was 0.42 [N / mm]. . If the adhesion strength is 0.4 [N / mm] or more, it is sufficient for practical use, and the seed layer thicknesses of 70 [nm] and 100 [nm] are sufficient for practical use. It can be said that it has strength. However, after forming a surface treatment layer on both sides of the polyimide substrate and forming 150 [nm] of nickel phosphorus as a seed layer, the above-described drying step (corresponding to S6 in FIG. 2) is performed, and then the polyimide substrate after being left for one week When the adhesion strength with the seed layer was measured, the adhesion strength was very low, 0.19 [N / mm].

  From the above results, by setting the film thickness of the seed layer to 100 [nm] or less, the moisture content inside the polyimide substrate can be greatly reduced by performing the drying process immediately after the formation of the seed layer. Therefore, as a result, the adhesion strength between the polyimide substrate of the laminate and the seed layer can be increased.

  From the viewpoint of reducing the moisture content inside the polyimide substrate, the film thickness of the seed layer should be 100 [nm] or less, and it should be as thin as possible. However, the film thickness of the seed layer will be formed later. When a metal layer (especially a copper thin film is used) is formed, it is formed by an electroplating method. However, if the seed layer has a film thickness of less than 70 [nm], the electric resistance becomes high, so electroplating. Current does not flow stably. That is, the thickness of the seed layer needs to be 70 [nm] or more from the viewpoint of forming a metal layer by electrolytic plating.

  In summary, the thickness of the seed layer is 70 nm or more and 100 nm or less from the viewpoint of reducing the moisture content inside the polyimide substrate and forming a metal layer by electrolytic plating. There is a need to.

  According to the laminated board and the laminated board manufacturing method of the present invention, it is possible to provide a laminated board in which a decrease in the adhesion strength between the polyimide substrate and the seed layer of the laminated board after the formation of 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.

1 Laminated plate 2 Polyimide substrate 3 Surface treatment layer 4 Seed layer 5 Metal layer

Claims (5)

A polyimide substrate;
A surface containing a metal formed by subjecting both surfaces of the polyimide substrate to an alkaline aqueous solution, and then applying a metal catalyst to the surface-treated portion and then reducing the metal catalyst. Processing layer,
A seed layer formed on the surface treatment layer;
A metal layer formed on the seed layer,
A laminated board, wherein the seed layer has a thickness of 70 nm to 100 nm.   The laminate according to claim 1, wherein the seed layer is an alloy containing nickel.   The laminated board according to claim 1, wherein the metal is palladium. 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
Then, a seed layer forming step of laminating a seed layer containing nickel on the surface treatment layer,
Thereafter, a drying step of removing moisture inside the polyimide substrate,
Thereafter, a metal layer forming step of laminating a metal layer on the heat-treated seed layer,
The manufacturing method of the laminated board which consists of.   The method for producing a laminated board according to claim 3, wherein the drying temperature in the drying step is 125 ° C, and the drying time in the drying step is 5 minutes.

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