JP2005217344A - Metal foil for printed circuit board, its manufacturing method, and printed circuit board using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal foil for a printed circuit board which realizes a stable electric connection with conductive resin composite, and keeps an adhesion capacity with insulating resin layer even when metal foil surface is reduced in roughness. <P>SOLUTION: The metal foil for the printed circuit board is provided to have a second metal layer of at least 1 layer or more which improves the above-mentioned metal layer in rust proofing and in adhesion with the insulating resin layer, and to have a projection of the same kind as a first metal projected upward. Since an adhesion between the metal foil and the insulating resin layer is excellent by using the metal foil for this printed circuit board even when surface roughness is reduced, an excellent connection reliability is realized at the time of interlayer connection. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metal foil used as a wiring layer of a printed wiring board, in particular, a metal foil having improved adhesion strength with an insulating resin layer in the printed wiring board, a manufacturing method thereof, and a printed wiring board using the same. is there.

  The metal foil used in conventional printed wiring boards increases the overall surface area by roughening the surface of the metal foil, and the protrusions are eroded into the insulating resin layer to ensure adhesion between the insulating resin layer and the metal foil. doing. As a method for roughening the metal foil in such a case, a method of roughening the surface of the metal foil by attaching relatively large metal particles to the surface of the metal foil by, for example, an electrolytic plating method is common (for example, patents). Reference 1).

  Moreover, this metal foil is surface-treated as a rust-proofing treatment for ensuring storage stability. Generally, a method of attaching Ni, Cr, Zn or an alloy layer thereof to the surface of the metal foil by an electrolytic plating method is effective, and these surface treatments also have an effect of increasing the adhesion between the insulating resin layer and the metal foil. A cross-sectional view of such a metal foil for printed wiring board is shown in FIG. The protrusion 2 is formed on the first metal layer 1, and the second metal layer 3 having a function of enhancing the adhesion between the rust prevention of the metal foil and the insulating resin layer on the surface thereof, A representative example of the printed wiring board using such a metal foil is that described in JP-A-6-268345 (see, for example, Patent Document 2).

  FIG. 2 shows a cross-sectional view of a printed wiring board using these conventional metal foils.

This printed wiring board realizes electrical connection between the wiring layers 4 and 5 by the conductive resin composition 7 filled in the through holes formed in the insulating resin layer 6.
Japanese Patent Application Laid-Open No. 5-243711 JP-A-6-268345

  In recent years, with the improvement of high-speed data communication and mobile network quality, there is an increasing demand for printed wiring boards that support high-speed and high-frequency transmission.

  Here, regarding the metal foil constituting the printed wiring board, the roughness of the metal foil affects the degree of loss of the signal transmitted through the wiring. As the roughness increases, the transmission loss increases and the printed wiring board becomes unsuitable for high-frequency transmission.

  Therefore, in order to provide a printed wiring board compatible with high-speed and high-frequency transmission, it is necessary to reduce the roughness of the metal foil.

  However, when a low-roughness metal foil is used, the adhesive strength between the metal foil and the insulating substrate is reduced, and problems such as peeling of the wiring layer occur.

  In order to solve the above problems, it is conceivable to form a thick second metal layer having a function of increasing the adhesive force between the insulating base and the metal foil.

  However, when such a metal foil is used for the printed wiring board shown in FIG. 2, the metal such as Ni, Cr, Zn, etc. forming the second metal layer has low conductivity, so The electrical connection between the resin compositions 7 becomes unstable.

  As described above, in the conventional metal foil, when the roughness is reduced, it is difficult to achieve both the adhesion with the insulating base material and the electrical connection with the conductive resin composition.

  The metal foil for printed wiring board of the present invention, the manufacturing method thereof, and the printed wiring board using the same are roughly divided to provide the following two types of metal foil to solve the above-mentioned conventional problems. It is.

(1) On one metal layer, it has at least one second metal layer that makes it possible to enhance the rust prevention of the first metal layer and the adhesion with the insulating resin layer. Metal foil for printed wiring board characterized by having the same type of protrusion as the discretely present first metal on the metal layer. (2) The first metal layer on the first metal layer having the protrusion. For printed wiring boards, characterized in that at least one or more second metal layers are formed so as to expose the tips of the protrusions. Metal foil When a metal foil having the structure of (1) and (2) is used for a printed wiring board, the second metal layer does not exist on the protrusion in the protrusion related to the electrical connection with the conductive composition. Therefore, a stable electrical connection can be obtained. On the other hand, even when the roughness is reduced, a sufficiently thick second metal layer can be formed, so that adhesion with the insulating resin layer can be ensured.

  The metal foil according to claims 2 and 11 of the present invention is the metal foil according to the above (1) and (2), wherein the second metal layer is composed of one or more metal layers, and at least one selected from Ni, Cr, and Zn. It is characterized by being a material containing two or more elements.

  The metal foil according to claims 5, 6, 14, and 15 of the present invention is characterized in that in the metal foil according to the above (1) and (2), an organic rust preventive layer is present on the outermost surface of the metal foil. Even if the silane coupling agent or the benzotriazole-based resin is on the surface of the metal foil, it does not affect the electrical connection. Furthermore, the metal surface is prevented from being oxidized, and the adhesion between the metal foil and the insulating resin layer can be increased, which is useful.

  Next, in the metal foil manufacturing method according to the seventh aspect of the present invention, the second metal layer is formed on the first metal by plating, and then the first metal protrusion is further formed by electrolytic plating. It is characterized by having. By such a manufacturing method, the metal foil for printed wiring boards as described in said (1) can be manufactured.

  According to a sixteenth aspect of the present invention, there is provided a method for producing a metal foil, comprising: forming a projection of the same type as the metal on the metal by electrolytic plating to obtain a first metal layer; A step of forming a metal layer. By such a manufacturing method, the metal foil for printed wiring boards as described in said (2) can be manufactured.

  The second metal layer and the protrusion may be on both sides of the first metal layer. The double-sided treated foil ensures good electrical connection and adhesion strength, particularly in the inner layer wiring of the multilayer substrate.

  The printed wiring board according to claims 8 and 17 of the present invention is composed of the metal foil according to the above (1) and (2), and the close contact portion with the insulating resin layer is a second metal layer, And it is the structure characterized by the protrusion biting into the insulating resin layer. Such a printed wiring board can ensure adhesion between the wiring layer and the insulating resin layer as described above even when the roughness is reduced.

  The printed wiring board according to the ninth and eighteenth aspects of the present invention is similar in form to the printed wiring board according to the eighth and seventeenth aspects. The difference is that a through hole is formed in the thickness direction of the insulating resin layer, and the through hole is filled with a conductive resin composition, and the wiring layers disposed on both sides of the insulating resin layer are electrically conductive. It is the point characterized by being electrically connected by the resin composition. Since the protrusions of the metal foil bite into the conductive resin composition, stable electrical connection is possible, and the adhesion strength between the wiring layer and the insulating resin layer can be ensured even when the roughness is reduced.

  When the printed wiring board shown in FIG. 2 is formed using the metal foil of the present invention, stable electrical connection with the conductive resin composition can be realized, and the roughness of the surface of the metal foil is small. Even in this case, it is possible to ensure adhesion with the insulating resin layer.

  An embodiment of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 3 shows a cross-sectional view of the metal foil according to the first embodiment of the present invention.

  The metal foil includes at least one second metal layer 3 that makes it possible to enhance the first metal layer 1, the rust prevention of the first metal layer, and the adhesion with the insulating resin layer, and the first metal layer On the second metal layer, a projection 8 made of the same material as the first metal is formed.

  The first metal constituting the metal foil is made of a material containing at least one element selected from Cu, Ag, Au, and Pt, and the second metal layer is selected from Ni, Cr, and Zn. A metal or the like of a material containing at least one element can be used.

  When such a metal foil is used as the wiring layer of the printed wiring board shown in FIG. 2, since the second metal layer does not exist on the protrusion 8, good electrical connection with the conductive resin composition is possible.

  On the other hand, even when the roughness of the metal foil is low, it is not necessary to form the second metal layer as thinly as the conventional metal foil, so that the adhesion with the insulating resin layer can be increased.

(Embodiment 2)
FIG. 4 shows a cross-sectional view of a metal foil according to Embodiment 2 of the present invention. This metal foil is a similar form of the first embodiment. The difference is that the first metal layer has a second metal layer and protrusions on both sides. When such a metal foil is used as the wiring layer of the printed wiring board shown in FIG. 2, particularly the inner layer wiring 5, good electrical connection with the conductive resin composition is possible on both sides of the metal foil, and the adhesiveness is also good. This improves the reliability of delamination and the like and improves the electrical characteristics.

(Embodiment 3)
FIG. 5 shows a cross-sectional view of a metal foil according to Embodiment 3 of the present invention. Although this metal foil is similar to the first embodiment, the difference is that an organic rust preventive layer 9 is formed on the outermost layer of the metal foil of the first embodiment. The organic rust preventive layer is preferably made of a material containing a silane coupling agent or a benzotriazole rust preventive agent. These organic rust preventive layers do not affect the electrical connection between the metal foil and the conductive resin composition, prevent oxidation of the metal surface, and increase the adhesion between the metal foil and the insulating resin layer.

  The three metal layers, the four protrusions, and the five organic rust preventive layers may be provided on both sides.

  If it is on both sides, it can also be used for the inner layer wiring of the wiring board of FIG. 2, and good electrical connection can be made with the conductive resin composition on both sides of the metal foil, and the adhesion is also improved, delamination As a result, there is an effect that the reliability and the electrical characteristics are improved.

(Embodiment 4)
FIG. 6 shows a method for manufacturing a metal foil for printed wiring board according to Embodiment 4 of the present invention.

  First, the 1st metal layer 1 which is metal foil shown in Fig.6 (a) is prepared. Next, as shown in FIG. 6B, a metal layer made of the second metal is formed on the first metal layer 1 by plating or the like. Next, as shown in FIG. 6C, the same metal as the first metal layer is formed by electrolytic plating or the like.

  By the above method, the metal foil according to the first embodiment can be manufactured.

  By applying this process to both surfaces of the first metal layer, the double-sided metal foil according to the second embodiment can be obtained. When applied to both sides, it can also be used for the inner layer wiring of the wiring board of FIG. 2, and it enables good electrical connection with the conductive resin composition on both sides of the metal foil, and also improves adhesion, delamination As a result, there is an effect that the reliability and the electrical characteristics are improved.

(Embodiment 5)
In FIG. 7, sectional drawing of the printed wiring board in connection with Embodiment 5 in this invention is shown.

  In this printed wiring board, the wiring layer is made of the first metal layer 1, the contact surface with the insulating resin layer 6 is the second metal layer 3, and the protrusion 8 made of the first metal bites into the insulating resin layer 6. It is the composition which is.

  High adhesion strength is obtained by the second metal layer being in contact with the insulating resin layer. Therefore, even when the roughness of the metal layer surface is small, the printed wiring board has a high adhesion to the insulating resin layer and becomes a highly reliable substrate.

(Embodiment 6)
In FIG. 8, sectional drawing of the printed wiring board in connection with Embodiment 6 in this invention is shown. This printed wiring board is a similar form of the fifth embodiment. The difference is that the protrusions also bite into the conductive resin composition 7.

  Stable electrical bonding can be achieved by bringing the metal protrusions that are not surface-treated into contact with the conductive resin composition. In addition, since it is not necessary to form the second metal layer as thinly as the conventional metal foil, the thick second metal layer can contact the insulating resin layer, and high adhesion strength can be obtained. Therefore, the printed wiring board is a substrate that has high adhesion to the insulating resin layer and can achieve high connection reliability when connected with the conductive resin composition even when the roughness of the metal foil surface is small.

(Embodiment 7)
FIG. 9 shows a cross-sectional view of a metal foil according to Embodiment 7 of the present invention.

  This metal foil makes it possible to improve the first metal layer 1, the same type of protrusions 8 as the first metal, and the rust prevention of the first metal layer and the adhesion between the protrusions and the insulating resin layer. It is composed of at least one second metal layer 3.

  The composition and effects of the metal foil are the same as those of the first embodiment, and the first metal layer constituting the metal foil has at least one element selected from Cu, Ag, Au, Pt, and the like. As the second metal layer, a metal species of a material containing at least one element selected from Ni, Cr, Zn, or the like can be used.

  When such a metal foil is used as the wiring layer of the printed wiring board shown in FIG. 2, since the second metal layer does not exist on the protrusion 8, good electrical connection with the conductive resin composition is possible.

  On the other hand, even when the roughness of the metal foil is low, it is not necessary to form the second metal layer as thinly as the conventional metal foil, so that the adhesion with the insulating resin layer can be increased.

(Embodiment 8)
FIG. 10 shows a cross-sectional view of a metal foil according to the eighth embodiment of the present invention. This metal foil is a similar form of the seventh embodiment. The difference is that the first metal layer has a second metal layer and protrusions on both sides. When such a metal foil is used as the wiring layer of the printed wiring board shown in FIG. 2, particularly the inner layer wiring 5, good electrical connection with the conductive resin composition is possible on both sides of the metal foil, and the adhesiveness is also good. This improves the reliability of delamination and the like and improves the electrical characteristics.

(Embodiment 9)
FIG. 11 shows a cross-sectional view of a metal foil according to the ninth embodiment of the present invention. This metal foil is a similar form of the seventh embodiment. The difference is that an organic rust preventive layer 9 is formed on the outermost layer of the metal foil of the seventh embodiment. The organic rust preventive layer is preferably made of a material such as a silane coupling agent or a benzotriazole rust preventive agent. These organic rust preventive layers do not affect the electrical connection between the metal foil and the conductive resin composition, prevent oxidation of the metal surface, and increase the adhesion between the metal foil and the insulating resin layer.

  Further, the three metal layers, the four protrusions, and the five organic rust preventive layers may be provided on both surfaces of the first metal layer. If it is on both sides, it will be possible to make good electrical connection with the conductive resin composition on both sides of the metal foil, as well as improving adhesion, improving the reliability against delamination and improving the electrical characteristics. .

(Embodiment 10)
FIG. 12 shows a method for manufacturing a metal foil for printed wiring board according to Embodiment 10 of the present invention.

  First, the first metal layer 1 shown in FIG. Next, as shown in FIG. 12B, protrusions 8 are formed on the first metal layer 1 by electrolytic plating with the same metal as the first metal layer 1. As the protrusion formation, conductive particles may be applied and sintered. Next, as shown in FIG. 12C, the metal layer 3 made of the second metal is formed by plating or the like. Next, as shown in FIG. 12D, the second metal layer on the surface of the protrusion is removed by etching or the like on the surface of the metal foil. At this time, if process conditions such as etching speed are appropriately selected, it is possible to remove only the second metal layer present on the protrusions.

  With the above method, the metal foil according to the seventh embodiment can be manufactured.

  By applying this process to both surfaces of the first metal layer, the double-sided metal foil according to the eighth embodiment can be obtained.

(Embodiment 11)
FIG. 13 shows a method for manufacturing a metal foil for printed wiring board according to Embodiment 11 of the present invention.

  First, the first metal layer 1 shown in FIG. 13A is prepared. Next, a metal layer made of a second metal is formed by plating or the like as shown in FIG. 13B. Next, a mask is formed on the metal layer made of the second metal as shown in FIG. Then, a through hole is formed in the second metal layer by etching or the like. Next, as shown in FIG. 13 (d), protrusions are formed by electrolytic plating or the like of the same metal as the first metal layer, and the mask is removed.

  With the above method, the metal foil according to the seventh embodiment can be manufactured.

  By applying this step to both sides of the first metal layer, a double-sided metal foil can also be obtained.

(Embodiment 12)
In FIG. 14, sectional drawing of the printed wiring board in connection with Embodiment 12 in this invention is shown.

  This printed wiring board is a similar form of the fifth embodiment. The difference is that the protrusion is joined to the first metal layer without the second metal layer.

  The same effect as in the fifth embodiment is obtained, and in this case, since the second metal layer having low electrical conductivity is not provided between the protrusion and the first metal layer, a better electrical connection can be obtained. Can do.

(Embodiment 13)
FIG. 15 is a sectional view of a printed wiring board according to the thirteenth embodiment of the present invention.

  This printed wiring board is similar to the twelfth embodiment. The difference is that the protrusions also bite into the conductive resin composition 7.

  Stable electrical bonding can be achieved by bringing the metal protrusions that are not surface-treated into contact with the conductive resin composition. Furthermore, in this case, since the second metal layer having low electrical conductivity is not provided between the protrusion and the first metal layer, a better electrical connection can be obtained. In addition, since it is not necessary to form the second metal layer as thinly as the conventional metal foil, the thick second metal layer can contact the insulating resin layer, and high adhesion strength can be obtained. Therefore, the printed wiring board is a substrate that has high adhesion to the insulating resin layer and can achieve high connection reliability when connected with the conductive resin composition even when the roughness of the metal foil surface is small.

(Comparative Example 1)
Copper protrusions are formed by electrolytic plating on 12 μm rolled copper foil (HCL-02Z, manufactured by Hitachi Cable Ltd.), and a second metal layer is formed in the order of Ni, Cr, and Zn to obtain a copper foil for a printed wiring board. It was. Ni, Cr, the adhesion amount of Zn in turn ^{0.15mg / dm 2, 0.20mg / dm} 2, was 0.04 mg / dm ^2. The surface roughness of the copper foil was measured using a surface roughness meter (Form Talysurf-120 manufactured by Rank Taylor Hobson Co., Ltd.). Rz = 2 μm.

  A method for measuring the ten-point average roughness Rz will be described. From the roughness curve, only the reference length L is extracted in the direction of the average line, and from the average line of this extracted part, the average value of the absolute values (Yp) of the highest summit (Yp) from the highest summit to the lowest summit To the sum of the absolute values of the elevations (Yv) of the valley bottom from the fifth to the fifth. The value obtained by (Equation 1) is expressed in micrometers (μm).

  Next, 150 μm diameter through holes were formed in a prepreg (MCL-E-679F manufactured by Hitachi Chemical Co., Ltd.) with a carbon dioxide laser, and the through holes were filled with the conductive resin composition by a printing method. The conductive resin composition was composed of 85% by weight of copper particles having an average particle diameter of 5 μm, 3% by weight of a bisphenol A type epoxy resin (manufactured by Epicoat 828 oiled shell epoxy), and an epoxy resin (YD- 171 manufactured by Toto Kasei) and 3% by weight of an amine adduct curing agent (manufactured by MY-24 Ajinomoto Co., Inc.) as a curing agent were kneaded in a three roll.

  Next, the prepreg filled with the conductive resin composition is sandwiched between the copper foils for the printed wiring board and laminated by heating and pressing at a temperature of 200 ° C. and a pressure of 5 MPa for about 1 hour in a vacuum using a hot press. After obtaining the board, a desired wiring pattern was formed by etching to produce a double-sided printed wiring board.

(Comparative Example 2)
A copper foil for a printed wiring board was obtained in the same manner as in Comparative Example 1 except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 5 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Comparative Example 3)
A copper foil for a printed wiring board was obtained in the same manner as in Comparative Example 1 except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 8 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Comparative Example 4)
A copper foil for a printed wiring board was obtained in the same manner as in Comparative Example 1 except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 12 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Comparative Example 5)
Ni, Cr, the adhesion amount of Zn in turn ^{0.55mg / dm 2, 0.36mg / dm} 2, except for using 0.09 mg / dm ^2, copper foil for printed circuit board in the same manner as in Comparative Example 1 Got. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 2 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Comparative Example 6)
A copper foil for a printed wiring board was obtained in the same manner as in Comparative Example 5, except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 5 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Comparative Example 7)
A copper foil for a printed wiring board was obtained in the same manner as in Comparative Example 5, except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 8 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Comparative Example 8)
A copper foil for a printed wiring board was obtained in the same manner as in Comparative Example 5, except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 12 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

  More specific embodiments of the present invention will be described in detail below.

(Example 1)
A second metal layer was formed in the order of Ni, Cr and Zn on a 12 μm rolled copper foil (HCL-02Z manufactured by Hitachi Cable, Ltd.). Ni, Cr, the adhesion amount of Zn in turn ^{0.55mg / dm 2, 0.36mg / dm} 2, was 0.09 mg / dm ^2. Next, copper protrusions were formed by electrolytic plating to obtain a printed circuit board copper foil. The surface roughness measured in the same manner as in Comparative Example 1 was Rz = 2 μm. A double-sided printed wiring board was produced in the same manner as in Comparative Example 1 using the copper foil for printed wiring board.

(Example 2)
A copper foil for a printed wiring board was obtained in the same manner as in Example 1 except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 5 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Example 3)
A copper foil for a printed wiring board was obtained in the same manner as in Example 1 except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 8 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

Example 4
A copper foil for a printed wiring board was obtained in the same manner as in Example 1 except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 12 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Example 5)
On the 12 μm electrolytic copper foil, a second metal layer was formed in the order of Ni, Cr, and Zn. Ni, Cr, the adhesion amount of Zn in turn ^{0.55mg / dm 2, 0.36mg / dm} 2, was 0.09 mg / dm ^2. Next, a dry film was laminated on both sides with a hot roll, a mask film was placed, and UV exposure was performed to cure the film only in the pattern portion. Thereafter, the uncured portion of the film was removed by a development process, and the second metal layer at the protrusion formation position was etched. Further, copper protrusions were formed by electrolytic plating to obtain a copper foil for a printed wiring board. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 2 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Example 6)
A copper foil for a printed wiring board was obtained in the same manner as in Example 5 except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 5 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Example 7)
A copper foil for a printed wiring board was obtained in the same manner as in Example 5 except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 8 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Example 8)
A copper foil for a printed wiring board was obtained in the same manner as in Example 5 except that the electrolytic plating conditions were adjusted to adjust the protrusion height. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 12 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

Example 9
A silane coupling agent (A-187 manufactured by Nihon Unicar Co., Ltd.) was sprayed onto the copper foil for printed wiring board created in Example 1, and dried to obtain a copper foil for printed wiring board. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 2.1 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

(Example 10)
A silane coupling agent (A-187 manufactured by Nihon Unicar Co., Ltd.) was sprayed onto the copper foil for printed wiring board prepared in Example 5, and dried to obtain a copper foil for printed wiring board. The surface roughness of this printed wiring board copper foil measured in the same manner as in Comparative Example 1 was Rz = 2.1 μm. Furthermore, the double-sided printed wiring board was produced by the method similar to the comparative example 1 using this copper foil for printed wiring boards.

  Table 1 shows a list of characteristics of the metal foils used in Examples 1 to 10 and Comparative Examples 1 to 8.

  The double-sided printed wiring boards of Examples 1-8 and Comparative Examples 1-8 were evaluated by the following methods.

(A) Initial conduction evaluation The resistance value of a chain wiring having 1600 vias was measured by a four-terminal method.

(B) Adhesion strength A peel test was performed to measure the adhesion strength. The test conditions are as follows.

Test apparatus: Tensilon UCT-100 manufactured by Orientec Co., Ltd.
Wiring width: 5 mm Isolation speed: 20 mm / min
An adhesion strength of 1 KN / cm ² or higher was evaluated as good, 0.8 to 1.0 KN / cm ² as Δ, and 0.8 KN / cm ² or lower as defective.

(C) Connection reliability evaluation A PCT test was performed to evaluate the reliability. The test conditions are as follows.

  After exposing the printed wiring board for 100 hours in an environment of 121 ° C. and 0.2 MPa, the resistance value of the chain wiring having 1600 vias was measured in the same manner as the initial conduction evaluation, and the rate of change from the initial resistance value was estimated. . A resistance value change rate of 30% or more was regarded as defective.

  It shows to Tables 2-4 about the result of having performed said evaluation.

  Tables 2, 3, and 4 (Embodiments 1 to 8 and Comparative Examples 1 to 8) will be described.

  In this experiment, Rz was set between 2 to 12 μm for a conventional metal foil structure, a metal foil having a thick second metal layer in the conventional metal foil structure, and a printed wiring board having the metal foil structure of the present invention. The effect of degree was evaluated.

  As for Comparative Examples 1 to 4, the conventional metal foil structure (thin second metal layer) showed a good initial connection, but the adhesion strength was lowered by lowering Rz, and the reliability was also degraded accordingly. did. This is because the anchor effect of the metal foil is lowered and the adhesion strength is weakened. Further, there is a relative relationship between the adhesion strength and the reliability, and the metal foil is peeled off due to stress due to humidity and temperature, so that a defect occurs.

  Regarding Comparative Examples 5 to 8, the conventional metal foil structure (second metal layer thickness) showed a high initial resistance value. This is because the thick second metal layer hinders electrical connection between the conductive resin composition and the metal foil. The adhesion strength was high due to the thick second metal layer. However, the reliability also deteriorated. There is a relative relationship between the initial resistance value and the reliability, and deterioration occurs between the metal foil that is unstable with respect to stress due to humidity and temperature and the conductive resin composition.

  On the other hand, the double-sided substrate of the metal foil structure of the present invention showed good initial conduction, high adhesion strength and reliability. In the metal foil of the present invention, since the second metal layer does not exist on the protrusion, good electrical connection with the conductive resin composition is possible even if the second metal layer is thick. Furthermore, since the adhesion strength is maintained by the thick second metal layer rather than the anchor effect due to the roughness of the copper foil, high adhesion strength and high reliability are obtained even if the surface roughness is low.

  Furthermore, the influence of the organic layer was investigated using the double-sided printed wiring boards of Examples 9 and 10. The used metal foil has an organic layer (silane coupling agent) in the outermost layer of the metal foil structure of the present invention. These samples showed good initial resistance, high adhesion and reliability. The presence of the organic layer does not adversely affect the initial resistance value, and the silane coupling agent and benzotriazole-based rust preventive are effective and effective in improving the rust prevention effect and adhesion strength.

  As described above, according to the present invention, when this metal foil is used, even when the roughness of the surface of the metal foil is small, the adhesion strength with the insulating resin layer is high, and the high connection reliability at the time of interlayer connection with the conductive resin composition Can be realized.

  The metal foil of the present invention is useful as a metal foil for forming wiring for printed wiring boards.

Schematic cross-sectional view of a general metal foil for printed wiring boards Schematic cross section of a general printed wiring board Typical sectional drawing of metal foil for printed wiring boards in a 1st embodiment of the present invention. Typical sectional drawing of the metal foil for printed wiring boards in the 2nd Embodiment of this invention Typical sectional drawing of the metal foil for printed wiring boards in the 3rd Embodiment of this invention Typical sectional drawing of the manufacturing method of the metal foil for printed wiring boards in the 5th Embodiment of this invention Typical sectional drawing of the printed wiring board in the 5th Embodiment of this invention Typical sectional drawing of the printed wiring board in the 6th Embodiment of this invention Typical sectional drawing of the metal foil for printed wiring boards in the 7th Embodiment of this invention Typical sectional drawing of the metal foil for printed wiring boards in the 8th Embodiment of this invention Typical sectional drawing of the metal foil for printed wiring boards in the 9th Embodiment of this invention Typical sectional drawing of the manufacturing method of the metal foil for printed wiring boards in 10th embodiment of this invention. Typical sectional drawing of the manufacturing method of the metal foil for printed wiring boards in the 11th Embodiment of this invention Schematic sectional view of a printed wiring board in a twelfth embodiment of the present invention Typical sectional drawing of the printed wiring board in the 13th Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st metal layer 2 Protrusion part 3 2nd metal layer 4 Outer layer wiring 5 Inner layer wiring 6 Insulating resin layer 7 Conductive composition 8 Protrusion 9 Organic rust prevention layer 10 Hole

Claims (18)

On the first metal layer,
Having at least one or more second metal layers that enable the first metal layer to have improved rust prevention and adhesion to the insulating resin layer,
Furthermore, the metal foil for printed wiring boards which consists of a metal of the same kind as said 1st metal on said 2nd metal layer, and has the processus | protrusion which exists discretely. The metal foil for printed wiring boards according to claim 1, wherein the second metal layer is a material containing at least one element selected from Ni, Zn, and Cr. 2. The printed wiring board metal foil according to claim 1, wherein the protrusion is formed by electrolytic plating. 4. The metal foil for printed wiring board according to claim 1, wherein the first metal layer is a material containing at least one element selected from Cu, Ag, Au, and Pt. 5. The metal foil for printed wiring boards in which the organic rust prevention layer is formed in the outermost layer in the metal foil of Claims 1-4. The metal foil for a printed wiring board according to claim 5, wherein the organic rust preventive layer comprises a layer containing a silane coupling agent and a benzotriazole resin. A step of forming, on the surface of the first metal layer, the second metal layer by plating, and thereafter forming protrusions made of the same kind of metal as the first metal and discretely present by plating. Manufacturing method of metal foil for printed wiring boards. A printed wiring board comprising the metal foil according to claim 1 and including a wiring layer and an insulating resin layer,
The adhesion portion with the insulating resin layer is the second metal layer,
And the printed wiring board which is the structure where the said protrusion part bites into the said insulating resin layer. A through hole is formed in the thickness direction of the insulating resin layer, the through hole is filled with a conductive resin composition, and the wiring resin layers arranged on both sides of the insulating resin layer are between the conductive resin composition. The printed wiring board according to claim 8, which is electrically connected by an object. On the first metal layer with protrusions,
A printed wiring board in which at least one second metal layer is formed so as to expose the tip of the protrusion, which makes it possible to improve the rust prevention of the first metal layer and the adhesion to the insulating resin layer. Metal foil. The metal foil for a printed wiring board according to claim 10, wherein the second metal layer is a material containing at least one element selected from Ni, Zn, and Cr. The metal foil for a printed wiring board according to claim 10, wherein the protrusion is formed by electrolytic plating. The metal foil for printed wiring boards according to claim 10, wherein the first metal is a material containing at least one element selected from Cu, Ag, Au, and Pt. The metal foil for printed wiring boards in which the organic antirust layer is formed in the outermost surface layer in the metal foil of Claims 10-13. The metal foil for printed wiring boards according to claim 14, wherein the organic rust preventive layer is made of a material containing a silane coupling agent and a benzotriazole resin. A print including a step of obtaining a first metal layer by plating the surface of the metal layer with the same type of protrusion as the metal, and a step of forming a second metal layer at a position lower than the tip of the protrusion. Manufacturing method of metal foil for wiring boards. A printed wiring board comprising a wiring layer made of the metal foil according to claim 10 and an insulating resin layer, wherein a close contact portion with the insulating resin layer is a second metal layer, and a protrusion is insulated. A printed wiring board with a structure that bites into the resin layer. A through hole is formed in the thickness direction of the insulating resin layer, the through hole is filled with a conductive resin composition, and the wiring resin layers arranged on both sides of the insulating resin layer are between the conductive resin composition. The printed wiring board according to claim 17, which is electrically connected by an object.

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