TW201636207A - Composite metal foil, method of manufacturing the same and printed circuit board - Google Patents

Abstract

Provided is a composite metal foil having a low-level stable peeling strength even if being subjected to heat compression steps, and a method of manufacturing the same. The composite metal foil includes a carrier made of a metal foil, a diffusion prevention layer formed on a surface of the carrier, a peeling layer made of metal which is formed by a physical deposition method and provided on the diffusion preventing layer, and a transfer layer made of metal which is formed by plating and provided on the peeling layer, wherein the metal of the peeling layer is the same element as the metal of the transfer layer, and the peeling layer is so formed by a physical film-forming method as to have a predetermined film density.

Description

Composite metal foil, manufacturing method thereof and printed wiring board

The present invention relates to a composite metal foil, a method of manufacturing the same, and a printed wiring board.

In recent years, in an electronic device that requires miniaturization and high processing speed, a semiconductor device mounted on a package substrate is mounted at a high density by using a printed wiring board having a multilayer structure in which a fine pattern (fine pattern) is formed.

Further, as a mounting component, a buildup substrate is used for rewiring, and basically consists of a support layer called a core layer and an accumulation layer which is wired on one or both sides. For the accumulation layer, a fine pattern is also required along with miniaturization of the element.

As a method of producing a printed wiring board which is suitable for forming a fine pattern, a copper-clad laminate formed by bonding an extremely thin copper foil to an insulating resin (hereinafter simply referred to as "substrate") is patterned by etching or the like. Methods. However, when the thickness of the copper foil is 12 [μm] or less, wrinkles and cracks are likely to occur when the copper clad laminate is formed. Therefore, it is known to use a support (hereinafter referred to as "carrier"). A method for producing a copper-clad laminate of a composite metal foil in which an extremely thin copper foil is laminated.

For a package substrate having a remarkable patterning development, in order to further downsize, an attempt has been made to thin the substrate by thinning the core layer or even omitting the core layer. In the patent documents 1 to 3, a method of manufacturing a substrate (hereinafter referred to as a "coreless substrate") in which a core layer is formed by forming an accumulation layer on a support and separating from the support is disclosed. Among them, a production method using the above composite metal foil as a support is disclosed.

In the above-mentioned composite metal foil, in the patent documents 4 to 6, various peelings such as an organic film containing an inorganic film such as chromium (Cr) or a nitrogen-containing compound having a substituent (functional group) are interposed on the carrier. A method of forming a copper foil with a layer and separating the copper foil film onto the substrate by separating the peeling layer.

Further, Patent Document 7 discloses a structure in which the composite metal foil has a diffusion preventing layer, a peeling layer made of copper, and a metal similar to the peeling layer using an acid plating bath. A composite metal foil of a transfer layer and a method of producing the same.

[Previous Technical Literature]

(Patent Document 1) Japanese Patent No. 4273895

(Patent Document 2) Japanese Patent Laid-Open Publication No. 2009-252827

(Patent Document 3) Japanese Patent Laid-Open Publication No. 2010-080595

(Patent Document 4) Japanese Patent Publication No. 56-34115

(Patent Document 5) Japanese Patent Laid-Open No. Hei 11-317574

(Patent Document 6) Japanese Patent Laid-Open Publication No. 2000-315848

(Patent Document 7) Japanese Patent Laid-Open Publication No. 2012-115989

In recent years, substrates using resins with high glass transfer temperatures have been used. In many cases, the conditions for heating and pressing are more severe. In the composite metal foil disclosed in Patent Documents 4 to 7, generally, the peeling strength of the carrier is increased by the heating application, and therefore, depending on the conditions of the heating application, there is a possibility that the peeling strength of the carrier is too high and peeling occurs. Defects (cannot be peeled off), and the entire ultra-thin copper foil is peeled off from the substrate.

On the other hand, in the coreless substrate, for example, in the manufacturing method disclosed in Patent Document 1, the heating application process for forming the accumulation layer is repeated a plurality of times, and the peel strength at the time of the final peeling becomes If it is too high, there is a possibility that the peeling failure and the accumulation layer are broken. Therefore, there is a need for a composite metal foil in which the peeling strength is stable even if the heating is repeated a plurality of times.

The present invention has been made in view of the above circumstances, and a main object thereof is to provide a composite metal foil having a low-stability peel strength even after a heating application process, and a method for producing the same.

The composite metal foil of the present invention is characterized by comprising: a carrier composed of a metal foil; a diffusion preventing layer formed on the surface of the carrier; and a peeling layer formed on the diffusion preventing layer by a physical film forming method a predetermined film density and composed of a metal; and a transfer layer formed on the release layer by electroplating and composed of a metal, the diffusion preventing layer suppressing metal atoms from the release layer to the carrier Diffusion, the metal constituting the peeling layer is copper which is the same element as the metal constituting the transfer layer, and the film density is adjusted so that the carrier, the diffusion preventing layer, and the peeling layer can be peeled off from the transfer layer. Laminated film.

In the structure of the composite metal foil of the present invention, the metal constituting the release layer and the transfer layer is copper, and the release layer is adjusted to maintain a predetermined film density by using a physical film formation method, even in forming a printed substrate. Heating A low stable peel strength can also be achieved after the pressing process.

As a physical film forming method for forming the release layer, vacuum deposition is preferably used, and a preferred film density of the release layer is 92% or more. The thickness of the release layer which keeps the peel strength stable at a low level is preferably 0.2 to 0.5 μm .

In the structure of the composite metal foil of the present invention, by providing the diffusion preventing layer, it is possible to prevent the metal atoms constituting the peeling layer and the transfer layer from being diffused to the carrier side by the heating application process, so that it is less likely to cause defects such as peeling. situation.

Here, the diffusion preventing layer is a single metal composed of any one of elemental groups of Ni (nickel), P (phosphorus), Co (cobalt), Mo (molybdenum), and Cr (chromium), or from the above element An alloy composed of two or more elements selected from the group, or a hydroxide, or an oxide, or a composite of the above single metal, alloy, hydroxide or oxide, and having a thickness of 0.05 to 1000 [mg/m ² ]. Further, the same layer may be formed also on the back side of the carrier.

Further, it is preferable to use a copper foil as the metal foil of the carrier.

The adhesion of the peeling layer can be evaluated in the cross-cut adhesion test in JIS-D0202 (1988). When the residual ratio of the cross-cut adhesion test is 10% or less, the strength required to peel off the laminated film composed of the carrier, the diffusion preventing layer, and the release layer after the transfer layer is formed (hereinafter referred to as "carrier peel strength") In the case of a heating test at 220 ° C for 4 hours, when the heating time [hr] is taken as the X axis and the peeling strength [kN/m] is taken as the Y axis, the heating time correlation of the peel strength is drawn, based on the most The slope of the approximate primary function of the Xiaoping method is 0.01 [kN/mhr] or less, and the carrier peel strength at this time (at the time of the heating test and before and after the test) is kept at 0.05 [kN/m] or less.

If the residual rate of the cross-cut adhesion test exceeds 10%, then After the heat, the stabilization of the lower position becomes difficult, and if the slope exceeds 0.01 [kN/mhr], the peel strength of the carrier after heating exceeds 0.05 [kN/m], the peeling itself becomes difficult, etc., and it is practical for the printed substrate. The problem.

The sum of the thicknesses of the peeling layer and the transfer layer is 0.2 [μm] or more and 12 [μm] or less. If the thickness is thin, formation of a coating becomes difficult, and peeling in a peeling layer becomes difficult, and if it exceeds 12 [micrometer], formation of a fine pattern becomes difficult.

Further, a laminated film composed of the diffusion preventing layer, the peeling layer, and the transfer layer may be formed on the back side of the carrier.

The method for producing a composite metal foil according to the present invention is characterized by the steps of: preparing a carrier composed of a metal foil; forming a diffusion preventing layer on a surface of at least one side of the carrier; and surface of the diffusion preventing layer a step of forming a release layer by a physical film formation method; and a step of forming a transfer layer by electroplating on the surface of the release layer.

By adjusting the film density of the peeling layer under the formation conditions of the physical film forming method, it is possible to keep the peel strength after the heating application process low and to prevent the copper-clad laminate from being caused by the increase in peel strength. The problem of manufacturing a printed circuit board.

The copper-clad laminate according to the present invention is characterized in that a laminated structure is formed by bonding the composite metal foil to a substrate for forming a copper-clad laminate, and the release layer of the laminate structure is borrowed. The carrier, the diffusion preventing layer, and the release layer are peeled off from the transfer layer, and the transfer layer remains on the substrate.

After the heating application process for bonding, in the process of peeling off the carrier, the diffusion preventing layer, and the peeling layer from the transfer layer, it is possible to prevent, for example, A copper-clad laminate can be produced with high yield due to defects such as peeling.

Further, the printed wiring board can be manufactured by patterning the transfer layer of the copper-clad laminate of the present invention.

The coreless substrate of the present invention is characterized in that a process of bonding a carrier of a composite metal foil and a support member of a coreless substrate is formed by a process of forming an accumulation layer including pressing the composite metal foil by heating An insulating layer made of a resin and a conductive layer for wiring made of a copper foil are bonded to the transfer layer side, and then the wiring for patterning the wiring for wiring is repeated one or more times; and in the transfer layer A process of peeling off the composite metal foil and the support member.

In the manufacturing process of the coreless substrate, even if the pressure application is repeatedly heated, the peel strength in the release layer can be kept low, and it is possible to suppress occurrence of defects in the peeling process of the support member and the composite metal foil.

According to the composite metal foil of the present invention, by providing the diffusion preventing layer, the film density of the peeling layer is optimized, and the peeling strength after the heating application is maintained at a low level, and the peeling failure due to the heating application can be prevented. The damage of the transfer layer, etc., and the deterioration of the peel strength. Further, by using the composite metal foil of the present invention to produce a printed wiring board or a coreless substrate, it is possible to prevent defects in the peeling process and to improve productivity.

1‧‧‧Composite metal foil

2‧‧‧ Carrier

3‧‧‧Diffusion prevention layer

4‧‧‧ peeling layer

5‧‧‧Transfer layer

5a‧‧‧ patterned transfer layer

6‧‧‧Substrate

7‧‧‧Printed wiring board

8‧‧‧Materials as a support

9‧‧‧Resin without core substrate

10‧‧‧ copper foil

11‧‧‧ accumulation layer

12‧‧‧ Coreless substrate

13‧‧‧Semiconductor components

14‧‧‧ Coreless package substrate

S1~S4‧‧‧ steps

Fig. 1 is a cross-sectional view showing a composite metal foil of a first embodiment.

Fig. 2 is a modification of the composite metal foil of the first embodiment.

Fig. 3 is a process chart showing a method of manufacturing a composite metal foil according to the first embodiment.

4(a) to 4(d) are process cross-sectional views corresponding to the respective processes of Fig. 3.

Fig. 5 is a graph showing the correlation of heat treatment time of peel strength.

6(a) to 6(c) are process diagrams showing a method of manufacturing a copper-clad laminate according to a second embodiment.

Fig. 7 is a cross-sectional view showing the printed wiring board of the third embodiment.

8(a) to 8(c) are process diagrams showing a method of manufacturing the coreless substrate of the fourth embodiment.

9(a) to 9(b) are process diagrams showing a method of manufacturing the coreless substrate of the fourth embodiment.

Figure 10 is a cross-sectional view showing a coreless substrate of a fourth embodiment.

Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings. However, in the assertion of the gist of the present invention, the embodiments and the examples do not provide a restrictive explanation. In addition, the same reference numerals are attached to the same or the same components, and the description is sometimes omitted.

[First Embodiment] [Structure of Composite Metal Foil]

First, the structure of the composite metal foil in the present invention will be described below. Fig. 1 is a schematic cross-sectional view showing an example of a composite metal foil in the present invention. The composite metal foil 1 is composed of a carrier 2 which is a support of a laminated film, a diffusion preventing layer 3 formed on the surface of the carrier 2, a peeling layer 4 formed on the surface of the diffusion preventing layer 3, and a surface formed on the peeling layer 4. The upper transfer layer 5 is formed. The carrier 2 is not particularly limited as long as it can have a heat resistance to the intended heating and can be a support for the laminated film formed on the upper layer. For example, a metal foil such as a copper foil or a copper alloy foil formed by a rolling method or an electrolytic method can be given. It will be composed of the diffusion preventing layer 3, the peeling layer 4, and the transfer layer 5 described above. The laminated film is formed on at least one side of the carrier, but may be formed on both sides.

In the case where a copper foil is used as the carrier 2, the thickness of the copper foil is preferably from 9 to 300 μm , more preferably from 18 to 35 μm , from the viewpoint of the treatment. The reason for this is that if the carrier is less than 9 μm , wrinkles and cracks are liable to occur, so that it is difficult to use as a carrier, and if it exceeds 300 μm , it is too strong and difficult to handle. In addition, when the surface roughness of the transfer layer 5 to be formed is reduced to a small thickness, the surface roughness of the carrier 2 is, for example, a rolled copper foil of RzJIS: 1.0 μm or less, or a special electrolytic copper foil. The carrier 2 is sufficient. In addition, RzJIS means the ten-point average roughness prescribed in JIS-B0601 (2013).

The diffusion preventing layer 3 is a film formed on the surface of the carrier 2 in order to prevent the metal atoms constituting the peeling layer 4 and the transfer layer 5 from being diffused to the carrier side (or mutually diffused) by the subsequent heat treatment process. Examples of such a material include a single metal composed of any one of elemental groups of Ni, P, Co, Mo, and Cr, or an alloy composed of two or more elements selected from the above element group, or hydrogen. An oxide, or an oxide, or a composite of the above single metal, alloy, hydroxide, or oxide.

The thickness of the diffusion preventing layer 3 is preferably from 0.05 to 1000 [mg/m ² ]. Further, the reason why the film thickness is expressed by the amount of adhesion (mass per unit area) is that the film thickness of the diffusion preventing layer 3 is extremely thin, so that it is difficult to directly measure.

When the film thickness of the diffusion preventing layer is extremely thin, a sufficient diffusion preventing function cannot be exhibited. In other words, when the printed wiring board or the coreless substrate is formed and heated and pressed, the metal atoms constituting the peeling layer 4 and the transfer layer 5 are easily diffused to the side of the carrier 2, which causes difficulty in peeling. Further, the thickness thereof is appropriately adjusted depending on the type of the metal forming the diffusion preventing layer. However, if the thickness exceeds 1000 mg/m ² , the cost of film formation increases, which is not preferable.

The peeling layer 4 is formed by a vacuum evaporation method. With respect to the release layer 4, by optimizing the formation conditions, peeling failure or the like does not occur even after the heating application process, and the release layer 4 can be separated from the carrier 2, the diffusion preventing layer 3, and the peeling layer 4 The laminated film composed of the layer 4 is peeled off from the transfer layer 5. Here, the thickness of the peeling layer 4 is preferably 0.2 to 0.5 μm as will be described later. If it is less than 0.2 [μm], the function as the peeling layer 4 is deteriorated, which is not preferable. On the other hand, when it exceeds 0.5 μm , the thickness of the film is increased as the thickness is increased, and the function as a peeling layer is deteriorated.

The vacuum evaporation method is a method suitable for the formation of a release layer. As described below, the vapor deposition output (electron beam power) is reduced from 45 [kW] to 35 [kW] or less in the conventional conditions, and the film density of the release film 4 is 92% or more, which is denser than ever. Membrane. Here, the film density is defined as a ratio of a density (specific gravity) and a bulk density (specific gravity) of a film formed by vapor deposition.

By optimizing the formation conditions of the release film 4, the adhesive force of the peeling layer 4 is 10% or less in the cross-cut adhesion test, and the heating time [hr] at 220 ° C and 4 hours is taken as When the X-axis and the peeling strength [kN/m] are plotted as the Y-axis and the heating time dependence of the peeling strength is plotted, the slope of the approximated first function based on the least squares method is 0.01 [kN/mhr] or less, and this can be made. The carrier peel strength at this time was 0.05 [kN/m] or less. Therefore, it is possible to prevent defects or the like in the peeling process at the time of manufacturing a copper clad laminate or a printed substrate.

The transfer layer 5 is a layer that serves as a conductor constituting a base material of the printed wiring board, and a metal having high conductivity may be used. Specifically, copper is preferred.

However, since the partial peeling layer 4 may be adhered to the transfer layer 5, it is necessary to pay attention to the adjustment of the thickness. That is, regarding the peeling layer 4 and the transfer layer 5 The sum of the thicknesses is preferably 0.2 to 12 [μm] because the influence on the fine patterning of the circuit is caused when transferring to the substrate constituting the printed wiring board. The reason for this is that, when it is less than 0.2 [μm], formation of a film becomes difficult, and the peeling function of the peeling layer 4 deteriorates. In addition, if it exceeds 12 [μm], formation of a fine pattern becomes difficult. Further, regarding the diffusion preventing layer 3, there was a case where the adhesion layer 3 was adhered, but the results of the investigation showed that the adhesion amount was extremely slight and it was not a problem.

Fig. 2 is a view showing a modification of the first embodiment. That is, in the case of the composite metal foil of Fig. 1, a laminated film is formed only on one surface of the carrier 2, but Fig. 2 shows an example in which the same laminated film is formed on both surfaces of the carrier 2.

[Method of Manufacturing Composite Metal Foil]

Next, a method of producing the above composite metal foil will be described. 3 is a view showing the steps of a method of manufacturing the above composite metal foil. 4 is a cross-sectional view of a process corresponding to each step of FIG. 3.

[Step S1]

First, as the carrier 2, a metal foil formed by a rolling method or an electrolytic method was prepared. (Fig. 4 (a)) Here, it is assumed that an untreated electrolytic copper foil (copper foil which has not been subjected to surface treatment) obtained by an electrolytic method is used. Further, it is set to have a thickness of, for example, 18 μm .

[Step S2]

Next, a diffusion preventing layer 3 is formed on the surface of the carrier 2. (Fig. 4(b)) Specifically, a plating bath for forming a diffusion preventing layer is prepared, and the surface of the carrier 2 is immersed in the plating bath to form a diffusion preventing layer 3 on the surface of the carrier 2 by electroplating. The diffusion preventing layer 3 is a single metal composed of any one of elemental groups of Ni, P, Co, Mo, and Cr, or an alloy or hydroxide composed of two or more elements selected from the above element group, or An oxide or a composite of the above single metal, alloy, hydroxide, or oxide is used. However, an example in which a composite layer composed of Ni, P, and Cr is formed as a diffusion preventing layer is shown. Further, the thickness thereof is, for example, 286 [mg/m ² ].

[Step S3]

Next, a peeling layer 4 is formed on the surface of the diffusion preventing layer 3. (Fig. 4(c)) The method for forming the release layer 4 is preferably a vacuum deposition method in which the vapor deposition output to form the release layer is 35 [kW], and the thickness of the release layer is 0.2 [ μm ] to form a release layer. The metal of 4 is preferably the same metal element as the metal constituting the transfer layer 5 formed in the next step S4.

[Step S4]

Next, the transfer layer 5 is formed on the surface of the peeling layer 4. (Fig. 4(d)) For the formation of the transfer layer 5, a chemical film formation method using an electroplating method, for example, an electrodeposition bath can be used. Regarding the transfer layer 5, in consideration of the use of copper, an acidic plating bath such as a copper sulfate plating bath is preferably used in consideration of industrial mass production. As a copper sulfate plating bath, the transfer layer 5 is formed to be predetermined by being impregnated into an electrolytic solution containing, for example, 100 [g/L] of sulfuric acid and 250 [g/L] of copper sulfate pentahydrate and energized at a predetermined current. The thickness can be. By this step, the composite metal foil 1 is completed.

By the detailed experiment described later, it is clarified that the film density of the peeling layer 4 formed by the physical film forming method can be adjusted according to the film forming conditions, and it can be adjusted by the plating method which is representative of the chemical film forming method. The peel strength of the transfer layer 5 and the peeling layer 4. Further, even if the peeling layer 4 remains as a residue on the surface of the transfer layer 5, since the peeling layer 4 is composed of the same metal element as the transfer layer 5, there is no adverse effect.

In addition, it is considered that the printed wiring board or the coreless substrate will be described later. Further, as a further step, in order to improve the adhesion to the substrate 6 constituting the printed wiring board or the material 8 as a support, the surface of the transfer layer 5 may be roughened.

In this case, the transfer layer 5 formed on the carrier 2 is subjected to cathodic electrolysis in a copper sulfate-sulfuric acid solution in the vicinity of a critical current density to form a roughened surface by dendritic or fine copper powder. Just fine. The surface roughness of the roughened surface is adjusted by the type of the substrate or the material as the support and the required adhesive force. The surface roughness is preferably RzJIS: 6 μm or less, and more preferably RzJIS: 2 [μm] or less in consideration of formation of an extremely fine fine pattern. In addition, RzJIS means the ten-point average roughness prescribed in JIS-B0601 (2013).

Further, in order to prevent the scattering of the copper powder, the transfer layer 5 subjected to the roughening treatment may be subjected to a coating treatment as needed.

When the printed wiring board 7 or the coreless substrate 11 described later is manufactured, the bonding of the substrate 6 or the material 8 as the support and the transfer layer 5 is reduced due to the heating application process, the etching process, and the like in the process. Happening. Therefore, for the purpose of maintaining the bonding state, Zn (zinc), Cr (chromium), Co (cobalt), Mo (molybdenum), Ni (nickel), P (phosphorus), W may be further used as the coating treatment. Coating treatment of a dissimilar metal such as (tungsten), chromic acid treatment using a solution containing dichromate ions, organic rust treatment using a solution containing benzotriazole, a decane coupling agent or a derivative thereof, or the like.

In addition, in consideration of the production of the coreless substrate 11, in order to bond the carrier 2 to the material 8 as a support, the carrier 2 may be subjected to the above-described roughening treatment, coating treatment, and coating treatment.

Hereinafter, specific embodiments will be described in more detail.

(Example 1)

First, an untreated electrolytic copper foil formed by a conventionally known method is prepared as the carrier 2 (step S1). On the surface of the carrier, a composite layer composed of Ni, P, and Cr is formed as the diffusion preventing layer 3 (step S2).

Next, in order to form the peeling layer 4, the vapor deposition output was 30 [kW] by a vacuum deposition method, and a copper layer having a thickness of 0.2 [ μm ] was formed (step S3). Further, in order to form the transfer layer 5 on the surface thereof, on the carrier on which the release layer 4 is formed, a transfer of a copper foil having a thickness of 4.8 [ μm ] is formed by a known sulfuric acid/copper sulfate plating bath. Layer 5 (step S4). Further, since the release layer 4 is a copper layer, if it is immersed in a copper sulfate plating bath for a long period of time, there is a possibility that the release layer 4 may be dissolved by the dissolution reaction, so it is necessary to start the formation transfer within 5 minutes at the latest. Electrodeposition of layer 5.

Finally, when the base material is a resin, the transfer layer 5 is subjected to a roughening treatment for the purpose of improving the adhesion to the transfer layer 5. In this case, in the roughening treatment, dendritic or fine copper powder is precipitated.

As a known roughening treatment, fine copper powder can be precipitated by a method disclosed in, for example, JP-A No. 1-246393.

Next, on the surface of the transfer layer 5 on which the copper coating is formed, a coating treatment by Ni, a zinc chromate treatment using Zn-Cr, and a decane coupling agent treatment are sequentially performed to obtain a composite metal foil 1.

(Example 2)

In the first embodiment, the composite metal foil 1 was obtained by the same procedure as in the above-described first embodiment except that the diffusion preventing layer was changed to a composite layer composed of Ni and P.

(Example 3)

In the first embodiment, the same steps as in the above-described first embodiment are performed except that the diffusion preventing layer is changed to a composite layer composed of Co, Mo, and Cr. A composite metal foil 1 was obtained.

(Example 4)

In the first embodiment, a composite metal foil was formed in the same manner as in Example 1 except that the peeling layer was a vapor deposition output of 35 [kW] and a thickness of 0.5 [ μm ]. 1.

(Example 5)

In the above-mentioned Example 4, the same procedure as in the above Example 4 was carried out except that the thickness of the diffusion preventing layer was 421.6 [mg/m ² ], and the composite metal foil 1 was obtained.

(Example 6)

In the first embodiment, the same procedure as in the above-described first embodiment was carried out except that the thickness of the transfer layer 5 was 1.3 [ μm ], whereby the composite metal foil 1 was obtained.

(Example 7)

In the above-described first embodiment, the same procedure as in the above-described first embodiment was carried out except that the thickness of the transfer layer 5 was 11.8 [ μm ], whereby the composite metal foil 1 was obtained.

(Comparative Example 1)

In the first embodiment, the diffusion preventing layer 3 was formed. However, in the comparative example 1, the diffusion preventing layer 3 was not formed, and the same procedure as in the above-described first embodiment was carried out to obtain the composite metal foil 1.

(Comparative Example 2)

In the first embodiment, the peeling layer 4 was formed. However, in the comparative example 2, the peeling layer 4 was not formed, and the same procedure as in the above-described first example was carried out to obtain the composite metal foil 1.

(Comparative Example 3)

In the first embodiment, the peeling layer 4 is a copper layer having a thickness of 0.2 [ μm ] formed by vapor deposition at 30 [kW] by a vacuum deposition method. However, in Comparative Example 3, the conventional steam was used. A composite metal foil 1 was obtained by performing the same procedure as in the above-described Example 1 except that a copper layer having a thickness of 0.2 [ μm ] was formed in 45 [kW] of the plating output.

(Comparative Example 4)

In the second embodiment, the peeling layer 4 is a copper layer having a thickness of 0.2 [μm] formed by vapor deposition at 30 [kW] by a vacuum deposition method. However, in Comparative Example 4, conventional vapor deposition was used. A composite metal foil 1 was obtained by performing the same procedure as in the above-described Example 2 except that 45 [kW] of the output was formed to have a copper layer having a thickness of 0.2 [μm].

(Comparative Example 5)

In the third embodiment, the peeling layer 4 is a copper layer having a thickness of 0.2 [μm] formed by vapor deposition at 30 [kW] by a vacuum deposition method. However, in Comparative Example 5, conventional vapor deposition was used. A composite metal foil 1 was obtained by the same procedure as in the above-described Example 3 except that the output of 45 [kW] was formed to form a copper layer having a thickness of 0.2 [μm].

(Comparative Example 6)

In the first embodiment, the thickness of the peeling layer 4 was set to 0.2 [μm], but in the same manner as in the above-described first embodiment, the thickness of the peeling layer 4 was changed to 0.01 [μm]. In the step, a composite metal foil 1 is obtained.

(Comparative Example 7)

In the first embodiment, the thickness of the peeling layer 4 was set to 0.2 [μm], but in the same manner as in the above-described first embodiment, the thickness of the peeling layer 4 was changed to 0.7 [μm]. In the step, a composite metal foil 1 is obtained.

(Comparative Example 8)

In the first embodiment, the peeling layer 4 is a copper layer having a thickness of 0.2 [μm] formed by vapor deposition at 30 [kW] by a vacuum deposition method. However, in Comparative Example 8, the vapor deposition was performed. The composite metal foil 1 was obtained by the same procedure as in the above-described Example 1 except that a copper layer having a thickness of 0.2 [μm] was formed by vapor deposition of 55 [kW] of a high output.

In Table 1, the production conditions of the above samples are summarized. In addition, in Table 1, the film density of the peeling layer under the sample preparation conditions, the cross-cut adhesion test residual ratio, and the peeling strength heating test result (including the slope with respect to heating time) are collectively described.

In addition, the film density (%) in Table 1 is defined by the ratio of the specific gravity of the film (release layer) formed by the above respective film formation conditions to the specific gravity of the same metal element in the volume, and is defined as The index of the density of the formed film is quantified. Therefore, the film density of 100% is the same specific gravity as the volume, and it can be considered that the closer the value is to 100%, the higher the density of the film.

(Table 1)

The cross-cut adhesion residual ratio was calculated as described above in accordance with the cross-cut adhesion test method in JIS-D0202 (1988).

The peel strength was in accordance with the test method of peel strength in JIS-C6481 (1996).

Further, the slope with respect to the heating time is the slope [kN/mhr] of the approximate linear function of the correlation of the heating time [hr] with respect to the peeling strength [kN/m] at a temperature of 220 ° C for 4 hours as described above. The stability of the peel strength was quantified. This means that if the value is small, the peel strength is small, that is, stable, with respect to the heating time.

5 is a graph showing the heating time dependence of the peel strength, showing the peel strength [kN/m] in the vertical axis (Y axis) and the heating time in the horizontal axis (X axis) [hr] As an example, for the first embodiment and the third comparative example, the measurement data and the straight line approximating the linear function are drawn. In comparison with Comparative Example 3, in the first embodiment, the slope of the approximated first function (hereinafter, simply referred to as "slope") was greatly lowered (improved), and the peel strength was improved.

In Table 1, it can be understood that the film density of all the conditions in Examples 1 to 6 shows a high value of 92% or more, and is dense under the condition that the vapor deposition output at the time of film formation of the peeling layer is low output. membrane. The cross-cut adhesion test having a good understanding of these conditions has a good residual ratio of 10% or less, and the peel strength in the heating test is 0.05 [kN/m] or less, and the slope is also 0.01 [kN/mhr] or less. The heat treatment is stabilized at a low level to ensure good peelability. By using a dense film as the peeling layer in this way, good results were obtained in the cross-cut adhesion test and the peeling strength heating test. Therefore, problems such as poor peeling can be solved.

On the other hand, when the conditions of Comparative Examples 3, 4, 5, and 8, that is, when the vapor deposition output at the time of film formation of the peeling layer is higher than those of Examples 1 to 6, the film density of the peeling layer is as low as 80%. Level, and the cross-cut adhesion test has a high residual rate. It was found that under these conditions, the peeling strength of the heating test was also high, and the slope also showed a large value, and the stability against the heat treatment was lacking.

Further, under the conditions of Comparative Examples 6 and 7, the vapor deposition output at the time of film formation of the peeling layer was as low as that of Examples 1 to 6. Therefore, although the film density was high, the cross-cut adhesion test residual ratio was high. Further, in the heating test of the peel strength, the peel strength was high, the slope thereof was also large, and the stability against the heat treatment was also deteriorated. That is, it is understood that the film thickness of the release layer is too thin or too thick, and the cross-cut adhesion test residual ratio and peel strength are deteriorated. From the results of Examples 1 to 6, it is understood that the thickness of the peeling layer needs to be set to be at least thicker than 0.01 [μm] and thinner than 0.7 [μm], preferably 0.2 to 0.5 μm .

Further, according to the results of the heat test of the cross-cut adhesion test residual ratio and the peel strength in Comparative Example 1 (no diffusion preventing layer), it is apparent that the existence of the diffusion preventing layer is required, and according to Comparative Example 2 (without peeling layer) As a result of the peeling strength heating test, it is apparent that the presence of the peeling layer is required.

Further, in the above-described examples and comparative examples, as the method of forming the peeling layer 4, only the vacuum vapor deposition method is described. However, the present invention is not limited thereto, and conventionally known physical materials may be used as long as a necessary film density is obtained. A film forming method such as a sputtering method or an ion plating method is used instead of the vacuum vapor deposition method.

[Second embodiment] [Method for producing copper-clad laminate)

Next, a method of manufacturing a copper-clad laminate using the composite metal foil 1 will be described. Fig. 6 is a view showing a process of producing a copper clad laminate by transferring the composite metal foil 1 on the substrate 6 of the printed wiring board.

As shown in Fig. 6(a), first, the composite metal foil 1 and the substrate 6 constituting the printed wiring board are opposed to each other, and then the two are adhered. Next, as shown in FIG. 6(b), a laminated structure of the composite metal foil 1 and the substrate 6 is formed by heating and pressing in a state of being adhered.

Then, as shown in FIG. 6(c), the release layer 2, the diffusion preventing layer 3, and the peeling layer 4 are peeled off from the laminated structure, and the transfer layer 5 is bonded to the substrate 6. That is, the copper clad laminate is completed. In addition, also The transfer layer 5 can be bonded to both surfaces of the substrate 6 to form a double-sided copper-clad laminate.

The peeling strength (peeling strength) at the time of peeling the product from the laminated structure is not less than 0.01 [kN/mhr] at 220 ° C for 4 hours, and the carrier peel strength at this time is 0.05 [ Since kN/m] or less, it is possible to suppress occurrence of peeling failure or the like. In addition, a part of the diffusion preventing layer 3 was left as a residue on the peeling layer at the time of peeling, but as a result of the investigation, it was confirmed that the amount was extremely slight, and there was no problem.

[Third embodiment] [Method of Manufacturing Printed Wiring Board]

A printed wiring board can be manufactured using the above-mentioned copper-clad laminate. Fig. 7 is a cross-sectional view showing a state in which a circuit pattern is formed in the copper clad laminate to produce a printed wiring board.

As shown in FIG. 7, the patterned transfer layer 5a is formed by an etching method or the like, thereby completing the printed wiring board 7 on which the circuit pattern is formed. Further, the composite laminated laminate may be further laminated as needed to form a printed wiring board having a multilayer structure.

[Fourth embodiment] [Method for producing coreless substrate]

The coreless substrate 11 can be manufactured using the above composite metal foil 1. Hereinafter, the method will be described. 8 is a view showing a process of manufacturing the coreless substrate 11 by laminating the composite metal foil 1 on the material 8 as a support, but the drawing is merely an example, and the present invention is not limited to the manufacturing method.

As shown in Fig. 8(a), first, the composite metal foil 1 and the material 8 as a support are opposed to each other, and then the two are bonded together to serve as a support. At this time, the surface facing the material 8 as the support is the carrier 2 side.

Next, as shown in FIG. 8(b), in the composite metal foil 1, on the side opposite to the surface to which the material 8 as the support is bonded, that is, on the transfer layer side, The resin 9 and the copper foil 10 of the coreless substrate are opposed to each other and heated and pressed to form a laminate.

Next, as shown in FIG. 8( c ), the copper foil 10 on the resin of the coreless substrate is patterned by an etching method or the like, and circuit formation, surface treatment, interlayer insulating film formation, and interlayer connection are performed, and the process is repeated. The process of laminating the resin/copper foil and heating and pressing is performed to form the accumulation layer 11 by a conventionally known method for producing a multilayer board.

Next, as shown in FIG. 9(a), the build-up layer 11 is peeled off by the peeling layer 4, and the coreless substrate 12 is obtained. At this time, the transfer layer 5 attached to the coreless substrate 12 side may be entirely removed or formed as a circuit, and is appropriately selected. Here, for example, an example in which a circuit is formed in the transfer layer 5 is shown.

Next, as shown in FIG. 9(b), the semiconductor element 13 is mounted and sealed in the coreless substrate 12, and the coreless package substrate 14 is completed. Further, as shown in FIG. 10, the composite metal foil 1 may be bonded to both surfaces of the material 8 as a support, and the coreless package substrate 14 may be produced on both surfaces.

The peel strength at the time of peeling off the coreless substrate is 0.01 [kN/mhr] or less under heat treatment at 220 ° C for 4 hours, and the carrier peel strength at this time is 0.05 [kN/m] or less. Prevent the occurrence of poor peeling and the like.

While the present invention has been described above with respect to the specific embodiments, the present invention is not intended to limit the scope of the invention, and the invention may be practiced otherwise without departing from the spirit and scope of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

1‧‧‧Composite metal foil

2‧‧‧ Carrier

3‧‧‧Diffusion prevention layer

4‧‧‧ peeling layer

5‧‧‧Transfer layer

Claims (14)

A composite metal foil comprising: a carrier composed of a metal foil; a diffusion preventing layer formed on a surface of the carrier; and a peeling layer formed on the diffusion preventing layer by a physical film forming method, having a predetermined a film density composed of a metal; and a transfer layer formed on the release layer by electroplating and composed of a metal, the diffusion preventing layer suppressing diffusion of metal atoms from the release layer to the carrier, thereby forming the above The metal of the peeling layer is copper which is the same element as the metal constituting the transfer layer, and the film density is adjusted so that the laminated film composed of the carrier, the diffusion preventing layer, and the peeling layer can be peeled off from the transfer layer. The composite metal foil according to claim 1, wherein the film density is 92% or more. The composite metal foil according to claim 1 or 2, wherein the peeling layer has a thickness of 0.2 to 0.5 μm . The composite metal foil according to claim 1, wherein the physical film forming method is a vacuum evaporation method. The composite metal foil according to claim 1, wherein: The scattering prevention layer is a single metal composed of any one of elemental groups of Ni (nickel), P (phosphorus), Co (cobalt), Mo (molybdenum), and Cr (chromium), or two selected from the above element group. An alloy composed of the above elements, or a hydroxide, or an oxide, or a single metal, or an alloy composed of two or more elements, or a composite of a hydroxide or an oxide. The composite metal foil according to claim 1, wherein the diffusion preventing layer has a thickness of 0.05 to 1000 [mg/m ² ]. The composite metal foil according to claim 1, wherein the metal foil is a copper foil. The composite metal foil according to claim 1, wherein the adhesiveness of the peeling layer after the formation of the peeling layer is 10% in the cross-cut adhesion test in JIS-D0202 (1988). the following. The composite metal foil according to claim 1, wherein the peeling strength of the carrier after the transfer layer is formed is a heating time [hr] at 220 ° C for 4 hours, and the peel strength is taken as the X-axis. [kN/m] When the heating time dependence of the above peeling strength is plotted as the Y-axis, the slope of the approximated first function based on the least squares method is 0.01 [kN/mhr] or less, and the carrier peeling strength is 0.05 [kN/ m] below. The composite metal foil according to claim 1, wherein the total thickness of the peeling layer and the transfer layer is 0.2 to 12 [μm] or less. A composite metal foil according to any one of claims 1 to 10, characterized by comprising the steps of: preparing a carrier composed of a metal foil; a step of forming a diffusion preventing layer on a surface of at least one side of the carrier; a step of forming a peeling layer by a physical film forming method on a surface of the diffusion preventing layer; and a surface on the surface of the peeling layer The step of forming a transfer layer by electroplating. A copper-clad laminate is formed by bonding a composite metal foil according to any one of claims 1 to 10 to a substrate for forming a copper-clad laminate, thereby forming In the peeling layer of the laminated structure, the carrier, the diffusion preventing layer, and the peeling layer are peeled off from the transfer layer, and the transfer layer remains on the substrate. A printed wiring board formed by forming a circuit pattern in a transfer layer of a copper clad laminate as described in claim 12 of the patent application. A method of manufacturing a coreless substrate by the following steps: a step of laminating a carrier of a composite metal foil according to any one of claims 1 to 10 and a support member of a coreless substrate; An accumulation layer forming step comprising bonding an insulating layer made of a resin to the transfer layer side of the composite metal foil by heating and pressing the copper foil The wiring layer for wiring is formed, and then the step of patterning the wiring conductive layer to form a wiring is repeated one or more times; and the step of peeling off the composite metal foil and the support member in the transfer layer.