JP5755371B2 - Ultra-thin copper foil with carrier, copper-clad laminate and coreless substrate - Google Patents

Description

  The present invention relates to an ultrathin copper foil with a carrier suitable for manufacturing a coreless substrate, and a copper-clad laminate composed of the ultrathin copper foil of the ultrathin copper foil with a carrier.

  As electronic devices become smaller and thinner, circuit board manufacturers are studying the production of multilayer laminates that use thinner substrates, called coreless substrates, and build-ups used in semiconductor packages, etc. There is a movement to replace a part of the substrate with a coreless substrate. However, since the coreless substrate does not have a core that supports the wiring layer, the coreless substrate has poor rigidity, and there is a concern that defects such as bending, warping, and cracking may occur during the formation of the wiring layer. Therefore, using the carrier foil of the ultrathin copper foil with carrier as a support, the build-up circuit board is laminated on the ultrathin copper foil side, finally peeling off the carrier foil of the ultrathin copper foil with carrier, A new manufacturing method to be taken out is being studied.

  The build-up substrate is formed with high-density wiring in which fine wiring layers (build-up layers) are stacked above and below a core layer that is a support. However, a conventional printed circuit board technology using a glass epoxy resin or the like is employed for the core layer, which causes the electrical characteristics to deteriorate. In particular, the large inductance component of the plated through hole penetrating the core layer is a factor that increases the power supply noise of the semiconductor chip. Therefore, the movement to adopt the coreless substrate without the core layer is rapidly progressing.

  A specific manufacturing process of a coreless substrate using an ultrathin copper foil with a carrier as a support will be described. The coreless substrate is manufactured through steps in order from (a) to (g) in FIG. A prepreg 4 is laminated on the ultrathin copper foil 2 of the ultrathin copper foil 3 with a carrier. An ultrathin copper foil 7 with a carrier for forming fine wiring is laminated on the prepreg 4. The carrier foil 5 of an ultrathin copper foil with a carrier for forming fine wiring is peeled off, and the ultrathin copper foil 6 is etched into a predetermined wiring pattern to form fine wiring 8. The prepreg 4 is again laminated on the fine wiring 8, and the first layer of the coreless substrate is completed. The steps (b) to (d) are repeated, and the coreless substrate 9 is formed on the ultrathin copper foil with a carrier serving as a support. Thereafter, the carrier foil 1 serving as the support is peeled off, and the outermost ultrathin copper foil 2 is finally removed by etching or the like, and only the coreless substrate as shown in (g) is taken out.

  In the manufacture of the coreless substrate, an ultrathin copper foil with a carrier is used also in forming fine wiring formed in the inner layer. When the carrier foil 5 is peeled off after the step (b) in FIG. 1, the carrier foil 1 used as a support is in the process of manufacturing the coreless substrate unless the carrier peel strength of the ultrathin copper foil 3 with a carrier is high. There is concern about peeling at an unintended stage. On the other hand, if the carrier peel strength is too high, a strong force is required when the coreless substrate is peeled off after the lamination process, and there is a concern that the coreless substrate may be bent or warped. Therefore, the peel strength at which the carrier foil 1 of the ultrathin copper foil 3 with a carrier is peeled from the ultrathin copper foil 2 requires appropriate adhesion in a manufacturing process such as plating or etching, but ultimately mechanically. Since it is necessary to peel off the coreless substrate without damaging it, it is desirable that it be 0.05 kN / m to 0.15 kN / m.

Regarding the peeling layer of the ultra-thin copper foil with carrier, for example, there are inventions described in Patent Documents 1 and 2, but neither is an invention intended to produce a coreless substrate. The present inventors have recognized that unexpected problems can occur when applied.
For example, in Patent Document 1 (WO2010 / 27052), in consideration of the temperature applied when manufacturing a multilayer laminate, even when placed in an environment at a high temperature of 300 ° C. to 400 ° C., the carrier foil For the purpose of easily peeling off the ultrathin copper foil, the main purpose is to peel off easily by defining two layers of peeling interfaces and defining the metal ratio of the peeling layer composed of two layers.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-188671) defines the contents of two types of metals A and B constituting the release layer, which are required to suppress the occurrence of swelling and have low peel strength. doing.

  However, contrary to the present invention, these proposals aim to keep the carrier peel strength low even after pressing under high temperature (300 ° C. to 400 ° C.) heating that is applied during the production of the laminate. When using a copper foil with a carrier having such a low carrier peel strength to produce a laminated board, particularly a coreless substrate, the force applied during the lamination process causes an unintended stage in the lamination process. Thus, there is a risk of occurrence of a problem that peeling occurs between the carrier foil serving as the support and the ultrathin copper foil.

WO2010 / 27052 JP 2007-186781 A

As described above, an ultrathin copper foil with a carrier having a high carrier peel strength is required in order to prevent the carrier foil and the copper foil from being peeled off at an unintended stage in the laminating process of the laminate.
In particular, after heating at a relatively low temperature (mainly 150 ° C. to 220 ° C. required for pressing a glass epoxy resin substrate or a bismaleimide triazine resin substrate) applied during the production of a coreless substrate, a moderately high carrier peel strength is obtained. There is a need for an ultra-thin copper foil with a carrier.
An object of this invention is to provide the ultra-thin copper foil with a carrier which satisfies such a request | requirement, and to provide the laminated board using this ultra-thin copper foil with a carrier.

According to the present invention, a carrier foil, an ultrathin copper foil, a metal A formed between the carrier foil and the ultrathin copper foil, one selected from Mo or W , and Fe, Co, Ni An ultrathin copper foil with a carrier having a release layer made of one type of metal B,
The release layer, two layers, i.e., the a first release layer which is formed on the carrier foil side, the is composed of a second release layer which is formed on the ultra-thin copper foil side,
The element ratio x1 of metal A and element ratio y1 of metal B in the first release layer is 70 (%) <{y1 / (x1 + y1)} × 100 ≦ 79 (%)
And the element ratio x2 of the metal A and the element ratio y2 of the metal B in the second release layer is 80 (%) <{y2 / (x2 + y2)} × 100 ≦ 88 (%)
A very thin copper foil with a carrier is provided.

  The ultrathin copper foil with a carrier of the present invention has a peel strength of 0.05 kN / m between the carrier foil and the ultrathin copper foil after heat treatment at 150 to 220 ° C. for 1 to 2 hours. It is preferable that it is 0.15 kN / m or less.

  The ultra-thin copper foil with a carrier of the present invention preferably has a diffusion prevention layer between the carrier foil and the release layer.

  In the ultrathin copper foil with a carrier of the present invention, the diffusion prevention layer is preferably formed of at least one metal or alloy selected from the group of Fe, Ni, Co, Cr, and alloys containing these elements. .

  In the ultrathin copper foil with a carrier of the present invention, the carrier foil is preferably copper or a copper alloy.

  The copper-clad laminate of the present invention is a copper-clad laminate obtained by laminating the ultrathin copper foil with a carrier described above on a resin base material.

  The ultra-thin copper foil with a carrier of the present invention prevents peeling of the carrier foil and the copper foil at an unintended stage during the laminating process of the multilayer laminate produced using the ultra-thin copper foil with the carrier, and the production process Stabilization and improvement in yield can be achieved.

FIG. 1 is a schematic view of a manufacturing process of a coreless substrate using an ultrathin copper foil with a carrier as a support. FIG. 2 is a schematic view showing an embodiment of an ultrathin copper foil with a carrier of the present application. FIG. 3 is a diagram showing current density conditions during plating when producing an ultrathin copper foil with a carrier of the present application.

  FIG. 2 shows an embodiment of an ultrathin copper foil with a carrier of the present application. The ultrathin copper foil with a carrier 10 is a carrier foil 11, a diffusion prevention layer 12 formed on the surface of the carrier foil 11, and a diffusion prevention layer 12. The release layer 13 is formed on the surface of the release layer 13 and the ultrathin copper foil 16 is formed on the surface of the release layer 13. The release layer 13 includes a first release layer 14 formed on the carrier foil side and a second release layer 15 formed on the ultrathin copper foil side. When the ultrathin copper foil is peeled off from the carrier foil, the first release layer 14 remains on the carrier foil side, and the second release layer 15 remains on the ultrathin copper foil side. Although the release layer is expected to have the same high carrier peel strength as that of the present application even when only the first release layer 14 is formed, the first release layer 14 is easily dissolved in the plating solution at the time of copper strike plating in the next step. Therefore, in order to prevent this, it is necessary to form the second release layer 15 so that the first release layer 14 does not directly contact the copper strike plating solution.

  As the carrier foil 11 for the ultrathin copper foil 10 with a carrier, aluminum foil, aluminum alloy foil, stainless steel foil, titanium foil, titanium alloy foil, copper foil, copper alloy foil, etc. can be generally used. From the viewpoint of simplicity, electrolytic copper foil, electrolytic copper alloy foil, rolled copper foil or rolled copper alloy foil is preferable.

  When a thin copper foil having a thickness of 7 μm or less is used for the carrier foil 11 that is a support in the manufacturing process of the coreless substrate, the mechanical strength of the carrier foil 11 is weak, so that the substrate may be wrinkled or bent during the manufacture of the coreless substrate. Eyes are easily generated and do not function sufficiently as a support. On the other hand, when the thickness of the carrier foil is 200 μm or more, the weight per unit coil (coil single weight) increases, which increases the production cost. Therefore, the thickness of the carrier foil is preferably 7 μm to 200 μm.

The release layer 13 is composed of a metal A that retains peelability and a metal B that facilitates plating of an ultrathin copper foil.
The metal A constituting the release layer is selected from the group of Mo, Ta, V, Mn, W, Cr, or an alloy containing these elements. Among these, it is particularly preferable to select from the group of Mo, Ta, V, Mn, W or an alloy containing these elements from the viewpoint of the safety of the chemical solution used for the treatment to the living body. In particular, the metal A is desirably selected from one of Mo and W.
Further, the metal B is selected from the group of Fe, Co, Ni, or an alloy containing these elements.

As schematically shown in FIG. 2, the release layer 13 includes two layers, that is, a first release layer 14 provided on the carrier foil 11 side and a second release layer 15 provided on the ultrathin copper foil 16 side. .
The composition ratio (element ratio) of the metal A that maintains the releasability of the first release layer 14 that constitutes the release layer 13 and the metal B that facilitates the plating of the ultrathin copper foil is the subject of earnest research by the inventors. result,
70 (%) <{y1 / (x1 + y1)} × 100 ≦ 79 (%)
It was found that the ratio of X1 is the element ratio of metal A, and y1 is the element ratio of metal B.

  If the ratio is 70% or less, the carrier peel becomes too low, and the carrier foil and the copper foil may be peeled off at an unintended stage during the lamination process of the laminate, and the ratio is 79. If it exceeds 50%, the carrier peel becomes too high, causing a problem that the ultrathin copper foil cannot be peeled off.

Regarding the composition ratio (element ratio) of the metal A that maintains the peelability of the second release layer 15 constituting the release layer 13 and the metal B that facilitates the plating of the ultrathin copper foil, the inventors' diligent research Result in
80 (%) <{y2 / (x2 + y2)} × 100 ≦ 88 (%)
It was found that the ratio of X2 is the element ratio of metal A, and y2 is the element ratio of metal B.

  When the ratio is 80% or less, the content ratio of the metal B for facilitating the plating of the ultrathin copper foil is small, and pinholes are generated in the ultrathin copper foil to be formed or blisters are generated. However, if it is 88% or more, the carrier peel strength becomes too high, which causes a problem that the ultrathin copper foil cannot be peeled off from the carrier foil.

  In addition, when two or more types of metals of the same genus in the metal A or the metal B are included, the element ratio is the sum of the element ratios of the metals of the same genus.

Formation of Diffusion Prevention Layer A diffusion prevention layer may be formed on the surface of the carrier foil 11 in order to stabilize the peelability of the ultrathin copper foil 16. By providing the diffusion preventing layer 12 in this way, the peelability of the release layer 13 is stabilized and effective. In this embodiment, Ni is used as the diffusion preventing layer, but the same effect can be obtained with Fe and Co.

Formation of Release Layer As an example of the production of the ultrathin copper foil 10 with a carrier, a diffusion prevention layer 12 for preventing diffusion of the elements of the carrier foil is first formed on the surface of the carrier foil 11, and then the first release layer 14 and the first release layer 14 are formed. Two release layers 15 are formed.
Each of the release layers 14 and 15 can be formed by electrolytic plating.
In order to change the metal composition of each peeling layer 14 and 15, it becomes possible by changing the concentration ratio (electrolytic bath composition) of the metal A and the metal B added to the electrolytic bath.
Alternatively, the metal composition can be changed by changing the plating conditions without changing the electrolytic bath composition. For example, the metal composition of each release layer can be changed by changing the current density.

Formation of ultrathin copper foil The ultrathin copper foil 16 is formed on the second release layer 15 by electrolytic plating using a copper sulfate bath, a copper pyrophosphate bath, a copper sulfamate bath, a copper cyanide bath, or the like. To do. Depending on the elements constituting the second release layer 15, in the electrolytic plating process for forming an ultrathin copper foil, the immersion time in the plating solution, the current density, the time of draining after plating, the time of washing with water, and the plating Depending on the pH of the solution, the second release layer may be damaged, so the plating bath composition, plating conditions, etc. must be carefully selected in relation to the elements constituting the second release layer.

In addition, in the formation of ultra-thin copper foil on the second release layer, it is difficult to perform uniform plating on the release layer, and pinholes are present in the formed ultra-thin copper foil and blistering occurs. There are things to do.
When uniform plating is difficult in this way, first, the surface of the second release layer 15 is subjected to strike copper plating in a copper pyrophosphate bath or the like, thereby reducing the metal A oxide while maintaining good and dense adhesion. By forming the base plating and applying normal copper plating on it, uniform plating can be applied on the second release layer, reducing the number of pinholes generated in the ultra-thin copper foil and generating blisters. Can be prevented.

The copper plating thickness to be deposited by the strike plating is preferably 0.01 μm to 0.5 μm, and the conditions vary depending on the bath type. The current density is 0.1 A / dm ^{2 to} 20 A / dm ² , and the plating time is Is preferably 0.1 seconds or longer. When the current density is 0.1 A / dm ² or less, it is difficult to uniformly deposit the plating on the release layer, and when the current density is 20 A / dm ² or more, the strike plating, in which the metal concentration of the plating solution is reduced, causes burn plating. In addition, a uniform copper plating layer cannot be obtained, which is not preferable. With respect to the plating time, 0.1 seconds or less is not preferable because it takes a short time to obtain a sufficient plating layer. The copper plating thickness formed on the release layer by strike plating needs to be a thickness that does not impair the peelability of the release layer, and is preferably 0.01 to 0.5 μm. After forming this strike plating layer, copper plating is performed to a desired thickness to obtain an ultrathin copper foil.

In the manufacture of the coreless substrate, the temperature applied in the pressing process is 150 ° C to 220 ° C.
The ultrathin copper foil with a carrier of this embodiment has an optimum carrier peel strength after passing through such a temperature region, and an etching process is performed to form a circuit on the ultrathin copper foil with a carrier in a coreless substrate manufacturing process. It has a high carrier peel strength that is strong enough to withstand the carrier peel strength against a load such as press treatment.

It is considered that the peeling phenomenon of the ultrathin copper foil with a carrier of the present invention occurs when a peeling interface is formed due to the presence of the metal A oxide. As a result of intensive studies by the inventors on the precipitation mechanism of the metal A oxide, it has been found that the metal oxide serving as the peeling interface does not precipitate unless coexisting with hydrogen gas. Hydrogen gas is generated by polarization (plating) at a base potential lower than the hydrogen overvoltage, and hydrogen gas is constantly generated when performed at a sufficiently low base potential. As a result, the amount of hydrogen gas generated is reduced as compared with the case where the operation is performed at a sufficiently low potential. The potential during plating can be controlled by changing the current density. When the cathode current is increased, the potential shifts in a base direction. For example, in the Mo—Co alloy plating bath used in the examples of the present application, the cathode current density is 0.4 A / dm ² and the potential is −1.12 V ( vs. Ag / AgCl / sat.KCl), and unsteady generation of hydrogen gas from the cathode starts. Thereafter, when the current density is increased, the slope of the polarization curve shows a constant value of −1.18 V / decade up to 1.0 A / dm ² (−1.22 V (vs. Ag / AgCl / sat. KCl)). However, when the current density is made higher than 1.0 A / dm ^2, the slope of the polarization curve decreases, and the amount of hydrogen generation increases rapidly compared to the region where the slope of the polarization curve is −1.18 V / decade, which is steady. Gas generation was observed. Carrier peel strength defined by the present, the potential having an inclination of -1.18V / decade on the polarization curve of the first separation layer as shown in FIG. 3 ^(a 0.4A / dm ² ~1.0A / dm 2 This is realized by manufacturing in the cathode current) region.
Also, simply reducing the plating time reduces the amount of metal A deposited, so it is necessary to control the amount of metal A deposited by adjusting the current density and time. When the plating conditions in Patent Documents 1 and 2 were reviewed, the plating was performed for a longer time under conditions where hydrogen gas was steadily generated than in the embodiment of the present application, and the ratio of the metal A in the release layer was the present application. It was found to be higher than the claims. On the other hand, in the embodiment of the present application, a new plating condition in which the deposition amount of the metal A oxide is small and the deposition ratio of the metal B is relatively high is made difficult to form a peeling surface with weak adhesion. This achieves the desired high peel strength.

Hereinafter, the present invention will be described in more detail with reference to examples.
[Example]

[Example 1]
A copper foil (thickness: 18 μm) having a surface roughness Rz of 1.1 μm on one side was used as a carrier foil, and Ni plating treatment was performed on the carrier foil to form a diffusion prevention layer.
Ni plating condition Ni 120g / L
H ₃ BO ₃ 30 g / L
pH 3.5
Bath temperature 50 ° C
Current density 20A / dm ²
Plating time 14.8s

On the carrier foil on which the diffusion preventing layer was formed, a first release layer was formed using a Co—Mo plating bath at a current density of 0.4 A / dm ² and a plating time of 6.0 s.
Co-Mo plating condition Mo 8.0g / L
Co 4.0g / L
Trisodium citrate 60g / L
pH 5.2
Bath temperature 25 ° C

After the first release layer is formed, the second release layer is immersed in a Co-Mo solution for 5.0 s, immersed in a plating solution, and at a current density of 0.3 A / dm ² and a plating time of 12.0 s. Formation was performed.
Next, copper strike plating is performed on this release layer under copper pyrophosphate plating conditions, and then copper plating is performed under thin copper foil plating conditions to form an ultrathin copper foil having a thickness of 3 μm. A foil was used.

Copper pyrophosphate plating conditions Copper pyrophosphate 19g / L
Potassium pyrophosphate 250g / L
pH 8.5
Bath temperature 40 ° C
Current density 1.2A / dm ²
Plating time 59.2s
Ultra-thin copper foil condition Cu 70g / L
H ₂ SO ₄ 50 g / L
Cl 25ppm
Current density 16.3 A / dm ²
Plating time 59.2s

[Examples 2 to 5]
An ultrathin copper foil with a carrier was prepared in the same manner as in Example 1 except that the plating conditions for forming the first release layer and the plating conditions for forming the second release layer in Example 1 were changed as shown in Table 1.

[Example 6]
A diffusion preventing layer similar to that of Example 1 was formed on the same carrier foil as that of Example 1. On the carrier foil on which the diffusion preventing layer was formed, a first release layer was formed using a Mo—Fe plating bath.
Mo-Fe plating conditions Mo 8.0 g / L
Fe 3.7 g / L
Trisodium citrate 60g / L
pH 4.0
Bath temperature 35 ° C
Current density 0.5A / dm ²
Plating time 6.0s

After the first release layer was formed, it was immersed in a Mo—Fe solution for 5.0 s. After immersion in the plating solution, a second release layer was formed at a current density of 0.3 A / dm ² and a plating time of 12.0 s. Next, copper strike plating and copper plating were performed on the release layer in the same manner as in Example 1 to form an ultrathin copper foil having a thickness of 3 μm to obtain an ultrathin copper foil with a carrier.

[Example 7]
A diffusion preventing layer similar to that of Example 1 was formed on the same carrier foil as that of Example 1. On the carrier foil on which the diffusion preventing layer was formed, a first release layer was formed using a Mo—Ni plating bath.
Mo-Ni plating conditions Mo 24.0 g / L
Ni 11.2g / L
Trisodium citrate 60g / L
pH 10
Bath temperature 25 ° C
Current density 0.8A / dm ²
Plating time 6.0s

After the first release layer was formed, it was immersed in a Mo—Ni solution for 5.0 s. After immersion in the plating solution, a second release layer was formed at a current density of 0.3 A / dm ² and a plating time of 12.0 s. Next, copper strike plating and copper plating were performed on the release layer in the same manner as in Example 1 to form an ultrathin copper foil having a thickness of 3 μm to obtain an ultrathin copper foil with a carrier.

[Example 8]
A diffusion preventing layer similar to that of Example 1 was formed on the same carrier foil as that of Example 1. A first release layer was formed on a carrier foil on which a diffusion prevention layer was formed using a W-Ni plating bath.
W-Ni plating conditions W 27.9g / L
Ni 11.2g / L
Trisodium citrate 60g / L
pH 10
Bath temperature 25 ° C
Current density 0.7A / dm ²
Plating time 6.0s

After the first release layer was formed, it was immersed in W-Ni liquid for 5.0 s. After immersion in the plating solution, a second release layer was formed at a current density of 0.3 A / dm ² and a plating time of 12.0 s. Next, copper strike plating and copper plating were performed on the release layer in the same manner as in Example 1 to form an ultrathin copper foil having a thickness of 3 μm to obtain an ultrathin copper foil with a carrier.

[Comparative example]
[Comparative Examples 1 and 2]
A diffusion preventing layer similar to that of Example 1 was formed on the same carrier foil as that of Example 1. On the carrier foil on which the diffusion preventing layer is formed, the amount of hydrogen generation is clearly less than or greater than that in Example 1 using a Mo—Co plating bath (the current density condition in Table 1 is a noble potential from the example). The first release layer was formed under the polarization condition and the polarization condition at a lower potential.
After the first release layer was formed, it was immersed in a Mo—Co solution for 5.0 s. After immersion in the plating solution, a second release layer was formed under the current density conditions shown in Table 1. Next, copper strike plating and copper plating were performed on the release layer in the same manner as in Example 1 to form an ultrathin copper foil having a thickness of 3 μm to obtain an ultrathin copper foil with a carrier.

[Comparative Examples 3 and 4]
A diffusion preventing layer similar to that of Example 1 was formed on the same carrier foil as that of Example 1. On the carrier foil on which the diffusion preventing layer was formed, a first release layer was formed under the current density conditions shown in Table 1 using a Mo—Co plating bath.
After the first release layer was formed, it was immersed in a Mo—Co solution for 5.0 s. After immersion in the plating solution, the second release layer was formed under the current density conditions shown in Table 1 (polarization conditions with a more noble potential than the examples and polarization conditions with a lower base potential). Next, copper strike plating and copper plating were performed on the release layer in the same manner as in Example 1 to form an ultrathin copper foil having a thickness of 3 μm to obtain an ultrathin copper foil with a carrier.

The produced ultrathin copper foil with a carrier was pressed under the conditions of a heat pressure of 150 ° C. × 1 hour, 180 ° C. × 1 hour, and 220 ° C. × 2 hours under a pressing pressure of 30 kgf / cm ^2. The substrate was laminated. Then, a circuit having a width of 10 mm was prepared, and the carrier peel strength was peeled off in a 90-degree direction using a tensile tester (manufactured by Toyo Baldwin, UTM-4-100) based on JIS C 6481-1996. It was measured. The measurement results are shown in Table 1.

  The ultrathin copper foil of the prepared sample is peeled off from the carrier foil, and the amount of attached elements (Mo, Co, Ni, W, Fe) remaining on the ultrathin copper foil side and the carrier foil side is measured with a fluorescent X-ray analyzer. It measured using. The measurement results are shown in Table 1.

Evaluation results [Examples 1 to 8]
In Examples 1 to 8, when the carrier foil and the ultrathin copper foil were peeled off, the ratio of the metal B to the release layer component remaining on the carrier foil and the ultrathin copper foil was 70% to 79%, respectively. And 80% to 89%. Carrier peel strength after heating at 150 ° C. × 1 hour, 180 ° C. × 1 hour, and 220 ° C. × 2 hours is from 0.050 kN / m to 0.150 kN / m, and is suitable for coreless substrate manufacturing. Strength was obtained.

[Comparative Example 1]
In Comparative Example 1, when the carrier foil and the ultrathin copper foil were peeled off, the ratio of the metal B to the release layer component remaining on the carrier foil and the ultrathin copper foil was 79.6% and 85.85%, respectively. The ratio of metal B on the carrier foil side exceeds 9%. For this reason, the carrier peel strength after heating at 150 ° C. × 1 hour, 180 ° C. × 1 hour, and 220 ° C. × 2 hours is higher than 0.150 kN / m, and high carrier peel strength is realized. When the carrier foil is peeled off, the coreless substrate may be damaged such as bending or bending when it is peeled off, which causes a problem in practical use.

[Comparative Example 2]
In Comparative Example 2, when the carrier foil and the ultrathin copper foil were peeled off, the ratio of the metal B in the peeling layer component remaining in the carrier foil was 70% or less, which was a value below the specification of the present application. Yes. Therefore, the carrier peel strength after heating at 150 ° C. × 1 hour, 180 ° C. × 1 hour, and 220 ° C. × 2 hours was less than 0.050 kN / m, and a high carrier peel was not realized.

[Comparative Example 3]
In Comparative Example 3, when the carrier foil and the ultrathin copper foil were peeled off, the ratio of the metal B in the release layer component remaining on the ultrathin copper foil was 88% or more, and the ultrathin copper foil side The ratio of metal B is equal to or greater than the provisions of the present application. For this reason, the carrier peel strength after heating at 150 ° C. × 1 hour, 180 ° C. × 1 hour, and 220 ° C. × 2 hours is higher than 0.150 kN / m, and high carrier peel strength is realized. When the carrier foil is peeled off, the coreless substrate may be damaged such as bending or bending when it is peeled off, which causes a problem in practical use.

[Comparative Example 4]
In Comparative Example 4, when the carrier foil and the ultrathin copper foil were peeled off, the ratio of the metal B in the peeling layer component remaining on the ultrathin copper foil was 80% or less, and the ultrathin copper foil side The ratio of metal B is not more than the provisions of the present application. Therefore, the carrier peel strength after heating at 150 ° C. × 1 hour, 180 ° C. × 1 hour, and 220 ° C. × 2 hours was less than 0.050 kN / m, and a high carrier peel was not realized.

  As a result of producing a coreless substrate in accordance with the coreless substrate production step using the ultrathin copper foil with a carrier produced in Example 1, it was possible to exfoliate without any trouble in the production process and in the exfoliation process.

DESCRIPTION OF SYMBOLS 1 Carrier foil of ultrathin copper foil with carrier for support 2 Ultrathin copper foil of ultrathin copper foil with carrier for support 3 Ultrathin copper foil with carrier for support 4 Prepreg 5 Ultrathin copper with carrier for fine wiring formation Foil carrier foil 6 Ultrathin copper foil with carrier for fine wiring formation 7 Ultrathin copper foil with carrier for fine wiring formation 8 Fine wiring 9 Coreless substrate 10 Ultrathin copper foil with carrier 11 Carrier foil 12 Diffusion prevention Layer 13 Release layer 14 First release layer 15 Second release layer 16 Ultrathin copper foil

Claims (7)

Metal A formed between a carrier foil and an ultrathin copper foil, the carrier foil and the ultrathin copper foil, one selected from Mo or W, and one selected from Fe, Co, and Ni An ultrathin copper foil with a carrier having a release layer made of B,
The release layer is composed of two layers, that is, a first release layer formed on the carrier foil side and a second release layer formed on the ultrathin copper foil side,
The element ratio x1 of metal A and element ratio y1 of metal B in the first release layer is 70 (%) <{y1 / (x1 + y1)} × 100 ≦ 79 (%)
And the element ratio x2 of the metal A and the element ratio y2 of the metal B in the second release layer is 80 (%) <{y2 / (x2 + y2)} × 100 ≦ 88 (%)
An ultra-thin copper foil with a carrier.   The peel strength at normal temperature between the carrier foil and the ultrathin copper foil after heat treatment for 1 to 2 hours at a temperature of 150 ° C. or more and 220 ° C. or less is 0.05 kN / m or more and 0.15 kN / m or less. Item 6. An ultrathin copper foil with a carrier according to Item 1.   The ultrathin copper foil with a carrier of Claim 1 or 2 which has a diffusion prevention layer between the said carrier foil and the said peeling layer.   The ultrathin copper foil with a carrier according to claim 3, wherein the diffusion prevention layer is formed of at least one metal or alloy selected from the group of alloys containing Fe, Ni, Co, Cr, and these elements.   The said carrier foil is copper or a copper alloy, The ultra-thin copper foil with a carrier in any one of Claims 1-4.   The copper clad laminated board formed by laminating | stacking the ultra-thin copper foil with a carrier in any one of Claims 1-5 on a resin base material. The coreless board | substrate produced using the ultra-thin copper foil with a carrier in any one of Claims 1-5 .

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