TWI402009B - Surface treatment of copper foil and circuit substrate - Google Patents

Description

Surface treatment copper foil and circuit substrate

The present invention relates to a surface-treated copper foil, and more particularly to a laminated circuit board (multilayer printed wiring board) which is suitable for conducting a circuit (line) provided on a front side and a back side with a conductive composition (conductive paste).

Further, the present invention relates to a circuit board in which a circuit is formed using the above surface-treated copper foil.

A method of manufacturing a conventional laminated circuit board includes a through-hole plating method in which a via hole is formed in an insulating layer after laminating a plurality of substrates for a multilayer circuit substrate, and coating is performed on an inner peripheral surface of the via hole. The treated coating is used to conduct interlayer conduction. The laminated circuit substrate formed by the through-hole plating method has the advantage that the layers can be connected with a low and stable contact resistance, but the process is complicated, the steps are large, and the cost is high, and the use of the laminated circuit substrate is limited. An important factor.

Further, in the laminated circuit board formed by the through hole plating method, there is a disadvantage that the components cannot be assembled directly above the through hole, and the degree of freedom in line layout is low.

In order to solve the above disadvantages, in the laminated circuit board formed by the through hole plating method, even a method of forming the through hole with respect to the substrate surface is used to avoid the arrangement position of the assembled component.

Further, in recent years, in the interlayer connection method which replaces the through-hole plating method, the laminated circuit substrate formed by the interstitial via hole (IVH) in which the conductive paste is filled in the through-hole has been put into practical use. . The laminated circuit board using the conductive paste can achieve a simplification and cost reduction of the manufacturing steps as compared with the laminated circuit board formed by the through hole plating method.

A representative method for manufacturing a laminated circuit using the IVH method is ALIVH (please refer to Non-Patent Document 1).

In the ALIVH, an aramid epoxy prepreg is used as an insulating substrate, and a through hole is formed by laser drilling. Next, a copper foil is laminated on both sides of the insulating substrate on which the through holes are filled with a conductive paste, and the copper foil and the insulating substrate are adhered by hot pressing. Thereafter, the copper foil is patterned (etched) to form a predetermined circuit. The above steps are repeated to form a laminated circuit substrate.

The copper foil used for the IVH method such as ALIVH has been developed to have a double-sided roughening treatment using a surface roughness of 4 μm or more in order to adhere to the adhesion of the guanamine epoxy resin prepreg and the connection with the conductive paste. Copper foil or single-sided roughening of copper foil. However, in recent years, home electric appliances and portable electronic devices that have been further developed have been continuously thinned and miniaturized, and there is a demand for fine patterning, but the surface-treated copper foil currently used cannot satisfy this demand.

[Non-Patent Document 1] Please refer to "High Performance Materials for Electronics Package Substrate" issued by CMC Publishing Co., Ltd. on January 31, 2005. Page 18

The present invention provides a surface-treated copper foil which can meet the requirements for fine patterning in the progress of miniaturization and miniaturization of household electrical appliances, portable electronic equipment, etc.; in particular, low surface roughness of a circuit structure suitable for the IVH method is provided. A surface-treated copper foil having a good adhesion to an insulating substrate and a low contact resistance with conductive paste metal particles.

Moreover, the present invention provides a circuit board in which a circuit is formed by the above-described surface-treated copper foil, whereby a circuit capable of forming a fine pattern is provided.

The surface-treated copper foil of the present invention is a surface-treated copper foil in which a copper foil line is formed on a laminated substrate, wherein the laminated substrate is provided with the copper foil line on the front and back surfaces of an insulating substrate. The metal particles filled in the via holes of the insulating substrate are connected to the copper foil line, and the surface treated copper foil is characterized by comprising: a surface treatment layer disposed on at least one surface of a copper foil base foil, The area of the joint surface of the joint portion of the copper foil-based foil bonded to the metal particles and the metal particles is 30% or more of the surface area of the copper foil-based foil.

Preferably, the surface treatment layer is a layer in which roughened particles are adhered to the surface of the copper foil-based foil, and the surface of the surface treatment layer has an Rz of 1.0 to 3.0 μm and a brightness value of 25 or less.

Here, Rz is defined in "Definition and Expression of Surface Roughness" in JIS B 0601-1194, which is "ten-point average roughness".

In addition, according to JIS Z 8105 (1982), the white surface illuminated by the same condition is the property of the relative brightness-related color of the surface of the reference object, and the brightness value is the scale of the property of the relative brightness-related color. value.

It is preferable that the surface treatment layer has 200 to 25,000 protrusions composed of the roughened particles having a height of 1 to 5 μm distributed in an area of 100 μm × 100 μm of the surface treatment layer.

In the range of 25 μm in the observation cross section of the surface treatment layer, the surface treatment layer preferably has 6 to 35 protrusions composed of the roughened particles having a height of 1 to 5 μm.

It is preferable that the maximum width between the protrusions in the surface treatment layer is 0.01 μm or more and 25 μm divided by twice or less the length of the number of the protrusions present in the range of 25 μm in the observation cross section.

The circuit substrate of the present invention is characterized in that it is made of a surface-treated copper foil.

The present invention can provide a surface-treated copper foil that can be thinned, sized, and miniaturized in order to meet the requirements of fine patterning, and is particularly suitable for the low surface roughness of the circuit structure of the IVH method, and A surface-treated copper foil having good adhesion to an insulating substrate and low contact resistance with conductive paste metal particles.

Further, the present invention can provide a circuit board in which a circuit is formed by the surface-treated copper foil described above, whereby a circuit capable of forming a fine pattern can be provided.

[Best form for implementing the invention]

The copper foil of this embodiment is a surface-treated copper foil, and is particularly suitable for a surface-treated copper foil which is formed by an IVH method.

A representative method for forming a laminated circuit using the IVH method will be described with ALIVH. 1(a) to 1(i) are cross-sectional views showing the steps of a method of manufacturing a laminated circuit substrate by ALIVH.

First, as shown in Fig. 1(a), a ruthenium epoxy resin prepreg is used as the insulating substrate 1; as shown in Fig. 1(b), the through hole 2 is formed by laser drilling.

Next, as shown in FIG. 1(c), the conductive paste 3 is filled in the through hole 2.

Next, as shown in FIG. 1(c), the copper foils 4 and 5 are laminated on both sides of the insulating substrate 1 in which the conductive paste 3 is filled in the through holes 2; and as shown in the first (d), heat is applied. The copper foil 4 and the insulating substrate 1 are adhered by pressure. The conductive paste 3 is melted by the heat of the hot pressing step, and the copper foils 4 and 5 on both sides are connected via the through holes 2 to be in an on state.

Next, as shown in Fig. 1(e), the copper foil is patterned (etched) to form a predetermined circuit. The single layer substrate 10 is formed as described above.

The above steps are repeated in order to multilayer the laminated substrate. For example, as shown in FIG. 1(f), the substrates 11 and 12 which are the same as the steps shown in the first (a) to (c) are formed, and are laminated on the upper surface and the lower surface of the substrate 10, respectively. Further, the copper foils 13, 14 are laminated on both sides of the laminate, and then the substrates 10, 11, 12 and the copper foils 13, 14 are adhered by hot pressing as shown in Fig. 1(g). The conductive paste is melted by the heat of the hot pressing step, and the double-sided copper foils 4 and 5 are connected to each other via the through holes. Thereafter, as shown in Fig. 1(h), the copper foil is patterned (etched) to form a predetermined circuit. As described above, a three-layer laminated laminated circuit substrate is formed.

In addition, the above process is repeated as needed. That is, the substrates 15 and 16 are respectively deposited on the upper surface and the lower surface of the laminated circuit substrate, and the copper foils 17 and 18 are laminated on both sides of the laminate, and the substrates and the copper foil are adhered by hot pressing. And the copper foils 17, 18 are patterned (etched) to form a predetermined circuit. Thereby, as shown in Fig. 1(i), a five-layer laminated circuit board is formed.

In the present embodiment, the copper foil before the surface treatment (hereinafter referred to as "copper foil base foil") is a copper foil or a copper alloy foil produced by electrolysis or rolling (if there is no need to distinguish between the two) Known as copper foil). The thickness of the copper foil is preferably from 1 μm to 200 μm. When the thickness of the copper foil is 1 μm or less, it is very difficult to carry out the roughening treatment on the surface of the copper foil, so the thickness of 1 μm or less is not preferable. The thickness of the copper foil used can be appropriately selected depending on the use thereof.

The surface roughness of the copper foil (copper foil base foil) is preferably from Rz 0.01 μm to 2 μm. Regarding the surface roughness of the copper foil-based foil, a copper foil-based foil having a Rz of 0.01 μm or less is practically difficult to manufacture, and even if it can be manufactured, the manufacturing cost is not in accordance with actual requirements; in addition, Rz can still be used. The copper foil-based foil of 2.0 μm or more is preferably 2 μm or less in consideration of high-frequency characteristics and fine patterning of the copper foil-based foil.

Here, the surface roughness Rz is defined as "Definition and Expression of Surface Roughness" in JIS B 0601-1994, and is a ten-point average roughness.

In the present embodiment, at least one side of the above-mentioned copper foil-based foil is subjected to a surface treatment.

The surface roughening treatment of the copper foil-based foil is such that the roughened particles adhere to the surface of the copper foil-based foil to form a roughened surface. The surface roughness Rz of the roughened surface is preferably from 1.0 to 3.0 μm. When Rz is less than 1.0 μm, the surface-treated copper foil for the purpose of achieving improved peeling strength cannot be satisfied because the peel strength is low. Further, when Rz is more than 3.0 μm, the high-frequency characteristics are not good and fine patterning cannot be achieved.

In the present embodiment, as for the surface treatment method of the copper foil-based foil, it is preferred that the copper foil-based foil or the copper alloy is adhered to the surface of the copper foil-based foil, and the adhesion amount of the copper or copper alloy is preferably 2 mg/dm. ² ~ 400mg / dm ² . When the adhesion amount is less than 2 mg/dm ² , the surface-treated copper foil for the purpose of achieving the improved peel strength cannot be satisfied because the peel strength is low.

When the adhesion amount is more than 400 mg/dm ² , the high-frequency characteristics are lowered and the amount of information transmission is lowered. The reason is that if the amount of adhesion of copper or copper alloy is large, the roughened particles are large, and the surface roughness is increased. . When a current flows through a conductor at a high frequency, the higher the frequency, the more the current tends to flow on the surface portion (skin effect). Therefore, if the roughness of the surface of the conductor increases, the length of the surface on which the current flows becomes longer and the resistance is increased, so that the loss of current increases and the amount of information transmission is insufficient. Therefore, the adhesion amount of copper or a copper alloy is preferably 400 mg/dm ² or less, but the upper limit of the adhesion amount may be ignored in the case where the use of the high-frequency characteristics is negligible.

In the present embodiment, the surface treatment of the copper foil-based foil is such that the surface is bonded to a conductive paste, and the joint portion of the surface with the metal particles contained in the conductive paste is bonded to the metal particles. The area is 30% or more of the surface area of the copper foil.

The contact area between the metal particles and the surface of the copper foil is the area measured as shown below.

First, the surface area of the copper foil was measured. That is, the cross section of the copper foil in the width direction and the longitudinal direction was measured. The length in the width direction obtained by measuring the cross-sectional portion of the surface of the copper foil was L, and the length in the longitudinal direction measured by the same method was L', and the result of multiplying L and L' was the surface area of the copper foil. The length of the cross-sectional portion was measured by using an image analysis software (Image Analysis Software ImageJ 2006 of BioArts Co., Ltd.), and the length of the surface of the copper foil was measured along the periphery of the roughened particles.

The total value of the length of the portion of the width L of the surface of the copper foil bonded to the metal particles of the conductive paste is S, and the length of the portion of the length L' of the surface of the copper foil bonded to the metal particles of the conductive paste is added. The value of S is the sum of the values of S and S'.

The joint area at this time is preferably 30% or more of the surface area of the copper foil. When the bonding area is 30% or more of the surface area of the copper foil, the adhesion can be satisfied, and the contact resistance between the copper foil (wiring circuit) and the metal particles can be lowered, and the connection portion can be satisfied between the two. When the contact area is 30% or less, the adhesion is insufficient, and there is a problem that the contact resistance increases and the heat is generated, which is not preferable.

The metal particles mixed in the conductive paste may be selected from aluminum, tungsten, lead, zinc, gold, silver, copper, nickel, cobalt, and the like.

Further, in the present embodiment, the roughened copper foil subjected to the surface roughening treatment has a lightness value of 30 or less, preferably 25 or less. The brightness value in the present embodiment is generally an index for observing the surface roughness, and the measurement method is a method in which light is irradiated on the surface of the measurement sample to measure the amount of reflection of light and is expressed as a brightness value. Here, according to JIS Z 8105 (1982), the brightness value is a value that scales the attribute of the related color of the relative brightness of the object, and is based on the white surface illuminated under the same condition. If the brightness of the treated surface of the surface-treated copper foil is measured by this method, the surface roughness Rz is large or the groove depth between the roughened particles is deep, and the lightness is low due to the small amount of light reflection. There is a tendency, and if the surface is smooth, the amount of reflection of light is large and the brightness tends to be high. In order to improve the peeling strength of the surface-treated copper foil and the insulating substrate, the surface-treated copper foil has a lightness value of 30 or less, preferably 25 or less. In addition, when the brightness exceeds 30, even if the Rz value of the roughened surface is large, the unevenness is a gentle unevenness, and the surface-treated copper foil and the insulating substrate are not well bonded, and the peel strength cannot be improved.

The brightness is measured by applying the copper foil to be tested.

Ni: 0.01~0.5mg/dm ²

Zn: 0.01~0.5mg/dm ²

Cr: 0.01~0.3mg/dm ²

After the rust-preventing treatment in the range, the measurement was carried out using a light meter (model name of SUGA TEST INSTRUMENTS CO., LTD: S&M Colour Computer model SM-4).

The surface treated copper foil of the present embodiment having the above surface roughness (Rz) and brightness value is laminated. After the compounding, it has excellent peel strength and fine patterning characteristics, and an excellent circuit substrate can be manufactured by using the surface-treated copper foil.

In the present embodiment, as described above, the roughening treatment is performed on the surface of the copper foil-based foil, and the projections formed by the roughened particles for achieving the average peel strength in the surface are preferably 100 μm × 100 μm. In the area, there are 200~25,000 protrusions. If the number of the protrusions is less than 200, the gap between the protrusions is wide and the fine pattern cannot be cut; if the number of protrusions is 25,000 or more, the protrusion is too narrow to provide sufficient peel strength, which is not preferable. .

Further, in order to obtain excellent peel strength and fine pattern characteristics without variation in the surface, it is preferred that the projections formed by the roughened particles described later are substantially uniformly distributed (distributed). That is, the height of the protrusions is preferably from 1.0 μm to 5.0 μm. When the height of the protrusion formed on the surface of the copper foil-based foil is 1.0 μm or less, the effect of improving the peel strength cannot be obtained because the height is low; when the height of the protrusion is 5.0 μm, the protrusion cannot be uniformly distributed, and the surface is not uniform. The surface roughness Rz of the treated copper foil becomes large in variation in each range, and the peel strength with stability cannot be maintained, and the high frequency characteristics are not good, and fine patterning cannot be achieved. The height referred to herein is the distance between the surface of the copper foil base foil and the apex of the protrusion.

Further, if the number of the projections is small, the peel strength cannot be achieved. If the number of the projections is large, the adhesion between the surface of the copper foil and the projections is small, and the effect is rather lowered. Therefore, the cross section is observed within 25 μm. It is preferred to have 6 to 35 protrusions, particularly preferably 10 to 20 protrusions.

Here, the concept of the protrusion referred to in the present embodiment will be described. The distance between the bottom of the groove portion formed between the adjacent protrusions and the apex of the protrusion (hereinafter referred to as the groove depth) is less than 0.3 μm, and such adjacent protrusion is regarded as one protrusion; When the depth of the projections is 0.3 μm or more, such adjacent projections are regarded as two projections. The height of the protrusion relative to the protrusion is the distance between the surface of the copper foil-based foil and the apex of the protrusion, and the depth of the groove is different from that of the bottom of the groove portion and the apex of the protrusion after the surface treatment. distance.

The method of counting the number of the protrusions is to embed the surface-treated copper foil in the resin, and to observe the cross section obtained by scanning with a scanning electron microscope (SEM), the count is in the range of 25 μm. The method of determining the number of the protrusions defined above is carried out.

Further, the number of protrusions having a height of 1.0 μm to 5.0 μm is 6 to 35 in the range of 25 μm, and a groove having a depth of 0.3 μm or more exists between the protrusions and is substantially uniformly distributed. It is possible to prevent the projections from being concentrated on a portion within 25 μm, and to stabilize the peel strength in the longitudinal direction of the copper foil in the longitudinal direction.

The term "substantially uniform distribution" in the present embodiment means that the number of protrusions having a height between 1.0 pm and 5.0 μm between the apex of the protrusion and the surface of the copper foil is n (pieces), and the protrusion is observed in section. When the observation width at the time of the object is 25 (μm), at least a part of one of the above-mentioned protrusions exists in the region of the width of (25/n) (μm).

Further, in order to stabilize the peel strength, the width of the formed protrusions is preferably uniform, and the maximum width of each of the protrusions is preferably 0.01 μm or more and 25 μm divided by 25 μm. The number of the projections is twice or less the length of the obtained length. The maximum width referred to herein means the maximum value of the distance in the direction perpendicular to the height direction of the projections in the SEM observation of the cross section.

Further, in the groove depth between the protrusions, the average groove depth between the protrusions is more preferably 0.5 μm or more. The average groove depth between the protrusions is the number of the protrusions on the two sides of the protrusions in the n-th projection having a groove depth of 0.3 μm or more, and the value at this time is A1 (μm) B1. (μm) ... An (μm) Bn (μm), the value obtained by the following formula is the average groove depth between the protrusions.

It is obtained by {[(A1+B1)+...+(An+Bn)]/2/n}.

Fig. 2 is a view showing the observation cross section of the surface-treated copper foil in the embodiment of the present invention.

A protrusion P is formed on the surface of the untreated copper foil SU. The number n of the projections P is 6 or more within 25 μm, for example, 6 to 35 are present, and the height thereof is in the range of 1 to 5 μm. When the groove depth indicated by a is less than 0.3 μm, the projections are not counted, but the projections having a groove depth of 0.3 μm or more as indicated by b are included. The maximum width W of the projections P is 0.01 μm or more, and 25 μm is divided by two times or less the length of the number of the projections P existing in the range of 25 μm.

Fig. 3 is a view showing an observation cross section of a poor surface-treated copper foil.

A protrusion P is formed on the surface of the untreated copper foil SU. The maximum width W of the projections P is 0.01 μm or more, and there is a projection P having an abnormal width which is greater than 25 μm in width and divided by the number of projections P present in the range of 25 μm.

Fig. 4 is a view showing an observation cross section of a poor surface-treated copper foil.

On the untreated copper foil surface SU, a protrusion P is formed which shows a cross section in which the protrusion P is not uniformly distributed. In Fig. 4, there is a region where there is no portion of the protrusion P as indicated by c, and this case cannot be regarded as a substantially uniform distribution.

A chromium and/or chromate coating film is formed on the copper foil of the roughened surface having the above-described configuration to perform rust prevention treatment, or a silane coupling agent treatment may be performed as needed or Anti-rust treatment plus decane coupling agent treatment.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by the following description.

<Example>

Prepare the following copper foil base foils one to four.

Copper foil base foil

Thickness: 12 μm; dark surface roughness: Rz = 1.26 μm; glossy surface roughness: Rz = 1.82 μm.

Copper foil base foil two

Thickness: 12 μm; dark surface roughness: Rz = 1.52 μm; gloss surface roughness: Rz = 1.46 μm.

Copper foil base foil three

Thickness: 12 μm; dark surface roughness: Rz = 1.86 μm; glossy surface roughness: Rz = 1.20 μm.

Copper foil base foil four

Thickness: 12 μm; roughness of both sides: rolled copper foil of Rz=1.20 μm.

The prepared copper foil-based foils were subjected to surface treatment with the following plating conditions A, B, or C from one to four. Table 1 shows the combination of the type of the copper foil-based foil and the plating conditions. Each of the examples is a surface-treated copper foil obtained by subjecting the copper foil-based foils to at least one plating in the order of plating bath 1 to plating bath 2 of plating conditions A, B, or C.

The surface shapes of the finished surface-treated copper foil were shown in Table 1 as Examples 1 to 8.

Further, in the roughened surface of some of the examples, nickel plating (0.3 mg/dm ² ), galvanization (0.1 mg/dm ² ) was applied, and chromate treatment was applied thereto.

Plating condition A Plating bath 1

Copper sulfate (source of copper metal) 5~10g/dm ³

Sulfuric acid 30~120g/dm ³

Ammonium molybdate (source of molybdenum metal) 0.1~5.0g/dm ³

Current density 10~60A/dm ²

Power-on time 1 second ~ 2 minutes

Bath temperature 20~60°C

Plating bath 2

Copper sulfate (source of copper metal) 20~70g/dm ³

Sulfuric acid 30~120g/dm ³

Current density 5~60A/dm ²

Power-on time 1 second ~ 2 minutes

Bath temperature 20~65°C

Plating conditions B Plating bath 1

Copper sulfate (source of copper metal) 1~50g/dm ²

Nickel sulfate (source of nickel metal) 2~25g/dm ³

Ammonium metavanadate (source of vanadium metal) 0.1~15g/dm ³

pH 1.0~4.5

Current density 1~60A/dm ²

Power-on time 1 second ~ 2 minutes

Bath temperature 20~60°C

Plating bath 2

Copper sulfate (source of copper metal) 10~70g/dm ²

Sulfuric acid 30~120g/dm ²

Current density 5~60A/dm ²

Power-on time 1 second ~ 2 minutes

Bath temperature 20~65°C

Plating conditions C Plating bath 1

Copper sulfate (source of copper metal) 1~50g/dm ²

Cobalt sulfate (cobalt metal source) 1~50g/dm ³

Ammonium molybdate (source of molybdenum metal) 0.1~10g/dm ³

pH 0.5~4.0

Current density 1~60A/dm ²

Power-on time 1 second ~ 2 minutes

Bath temperature 20~60°C

Plating bath 2

Copper sulfate (source of copper metal) 10~70g/dm ²

Sulfuric acid 30~120g/dm ²

Current density 5~60A/dm ²

Power-on time 1 second ~ 2 minutes

Bath temperature 20~65°C

<Comparative example>

The prepared copper foil base foils one, three, and four were subjected to surface treatment with the following plating conditions A' or B'. The combination of the type of the copper foil-based foil and the plating conditions was recorded in Table 1. Each of the comparative examples is a surface-treated copper foil obtained by subjecting the copper foil-based foil to one or three plating baths 1 to B in the order of plating conditions A' or B'. In Comparative Example prepared surface-treated surface side of the engagement surface (roughened surface) of the copper foil and the insulating substrate, subjected to nickel plating (0.3mg / dm ^2), zinc (0.1mg / dm ² Then, chromate treatment was carried out thereon, and it became a test piece of a comparative example.

The surface shapes of the surface-treated copper foil which were produced were the same as Comparative Examples 1 to 6, and are shown in Table 1.

Plating conditions A’ Plating bath 1

Copper sulfate (source of copper metal) 5~10g/dm ³

Sulfuric acid 30~120g/dm ³

Ammonium molybdate (source of molybdenum metal) 0.1~5.0g/dm ³

Current density 10~60A/dm ²

Power-on time 1 second ~ 2 minutes

Bath temperature 20~60°C

Plating bath 2

Copper sulfate (source of copper metal) 20~70g/dm ³

Sulfuric acid 30~120g/dm ³

Current density 3A/dm ²

Power-on time 2 minutes or more (change time according to surface roughness)

Bath temperature 15 °C

Plating conditions B’ Plating bath 1

Copper sulfate (source of copper metal) 1~50g/dm ²

Nickel sulfate (source of nickel metal) 2~25g/dm ³

Ammonium metavanadate (source of vanadium metal) 0.1~15g/dm ³

pH 1.0~4.5

Current density 1~60A/dm ²

Power-on time 1 second ~ 2 minutes

Bath temperature 20~60°C

Plating bath 2

Copper sulfate (source of copper metal) 20~70g/dm ²

Sulfuric acid 30~120g/dm ²

Current density 3A/dm ²

Power-on time 2 minutes or more (change time according to surface roughness)

Bath temperature 15 °C

[Measurement of Peel Strength ‧ Judgment]

After the surface-treated copper foil prepared in the examples and the comparative examples was cut into a length of 250 mm and a width of 250 mm, the surface subjected to the roughening treatment was placed in a BT resin having a thickness of 1 mm after thermocompression bonding ( The trademark of Mitsubishi Gas Chemical Co., Ltd. is a thermosetting resin composed of bismaleimide triazine resin, which is sandwiched between two smooth stainless steel plates. The peeling strength of the attached was measured by thermocompression bonding at a temperature of 190 ° C and a pressure of 50 kg/cm ^{2 for} 90 minutes.

The peel strength was measured and peeled off in a 180 degree direction in accordance with JIS C6471.

As is clear from Table 1, each of the examples satisfies the peel strength of 0.9 KN/m or more, but the peel strength in Comparative Examples 1 to 6 is 0.8 KN/m, and the peel strength is not satisfied.

[Micrographic feature evaluation]

Fig. 5 is a schematic cross-sectional view showing the surface-treated copper foil F produced as described above attached to a substrate SB of a BT resin or the like, and processed as described below.

As shown in Fig. 5, the copper foil F on which the resist R having the line width: L and the width: S is formed is etched with a ferric chloride bath. The etching time is determined by the same width of the top of the line width and the width of the resist. The substrate having the resist R which determines the width of each line and the width of each interval (forming 10 lines on one substrate) is formed under the condition of n=10. Etching was performed in the ferric chloride bath at the time determined above. In each of the substrates, it was observed that no bridging occurred between the wires, no residual root portion, and the top width of the wires was the same as that of the resist. The values of the smallest L‧S in the case where no bridge and residual root were observed in each of the substrates prepared under the condition of n = 10 are shown in Table 1.

As is clear from Table 1, in each of the examples, a fine pattern of L/S = 30/30 or less can be produced. Although each of the comparative examples other than Comparative Example 6 can be made into a 30/30 pattern, it is impossible to reduce it. Further, Comparative Example 6 was suitable for forming a fine pattern because the surface treatment roughness was small.

[Measurement of increase rate of resistance after heating]

After the core hole was opened from the BT resin and the conductive paste was filled, press-bonding was performed to bond the copper particles to the copper foil, and the resistance value was measured. The measurement results are shown in Table 1 as the increase rate of the resistance value after heating by the above-described press-fitting.

As is clear from Table 1, the increase rate of the electric resistance value after the heat treatment of each of the examples was 60% or less. On the other hand, the increase rates of the electric resistance values after the heat treatment of Comparative Examples 1 to 6 exceeded 140%.

Further, after the moisture resistance test, the resistance value in the same place was measured, and the increase rate of the resistance value before and after the moisture resistance test was calculated, and the advantages and disadvantages thereof were confirmed.

As is clear from Table 1, the increase rate of the electric resistance value after the moisture resistance test of each of the examples was 100% or less. On the other hand, the increase rates of the electric resistance values after the moisture resistance test of Comparative Examples 1 to 6 exceeded 140. %.

[Measurement of brightness]

The method of measuring the brightness is the same as described above. In one embodiment, the lightness is 25 or less, and in Comparative Examples 1 to 6, it is 30 or more.

As described above, in each of the examples, the bonding area of the metal particles and the copper foil is 30% or more, and the resistance value after the peeling strength, the brightness, the electric resistance value, the heating test, and the moisture resistance test can be made. The ratio of the micro-patterns to the conditions of the copper foil. On the other hand, the joint area of the metal particles of Comparative Examples 1 to 6 and the copper foil was 30% or less, and the results of satisfying the increase in the resistance value after the heat resistance test and the moisture resistance test were not obtained. The conditions for the peel strength and the formation of the fine pattern could not be satisfied, and the copper foil satisfying all the conditions was not obtained.

The present invention is to complete a surface-treated copper foil in which protrusions are formed on the surface of a copper foil, and the protrusions exhibit a specific shape and distribution formed by roughened particles, thereby ensuring strong adhesion even if the roughness is small. And a bonding area with the metal particles of the conductive paste, and a surface-treated copper foil which maintains stable electrical conductivity can be provided.

1. . . Insulating substrate

2. . . Through hole

3. . . Conductive paste

4. . . Copper foil

5. . . Copper foil

10. . . Substrate

11. . . Substrate

12. . . Substrate

13. . . Copper foil

14. . . Copper foil

15. . . Substrate

16. . . Substrate

17. . . Copper foil

18. . . Copper foil

a. . . When the groove depth is less than 0.3μm

b. . . When the groove depth is 0.3 μm or more

c. . . Area where no part of the protrusion P exists

P. . . Protrusion

R. . . Resistor

SB. . . Substrate

SU. . . Untreated copper foil surface

W. . . Maximum width

The first (a) to (i)th drawings are step diagrams illustrating the steps of the IVH method.

Fig. 2 is a schematic cross-sectional view showing an embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view showing a cross section of a surface-treated copper foil having a poor cross-sectional shape in a surface-treated copper foil.

Fig. 4 is a schematic cross-sectional view showing a cross section of a surface-treated copper foil having a poor cross-sectional shape in a surface-treated copper foil.

Fig. 5 is a cross-sectional explanatory view for explaining an etching width in formation of a fine pattern.

1. . . Insulating substrate

2. . . Through hole

3. . . Conductive paste

4. . . Copper foil

5. . . Copper foil

10. . . Substrate

11. . . Substrate

12. . . Substrate

13. . . Copper foil

14. . . Copper foil

15. . . Substrate

16. . . Substrate

17. . . Copper foil

18. . . Copper foil

Claims (6)

A surface-treated copper foil which is a surface-treated copper foil in which a copper foil line is formed on a laminated substrate, wherein in the laminated substrate, the copper foil line is provided on the front and back surfaces of an insulating substrate, and The metal particles filled in the via holes of the insulating substrate are connected to the copper foil line, and the surface treated copper foil comprises: a surface treatment layer disposed on at least one surface of a copper foil base foil, and the copper foil base foil is provided The area of the joint surface of the joint portion joined to the metal particles on the surface of the metal particles is 30% or more of the surface area of the surface-treated copper foil. The surface-treated copper foil according to claim 1, wherein the surface-treated layer is a layer to which roughened particles are attached to the surface of the copper foil-based foil, and the surface of the surface-treated layer has an Rz of 1.0 to 3.0 μm. The brightness value is below 25 (inclusive). The surface-treated copper foil according to claim 1, wherein the surface treatment layer has an area of 100 μm × 100 μm in the surface treatment layer, and 200 to 25,000 heights of 1 to 5 μm are distributed by the roughening. a projection made up of particles. The surface-treated copper foil according to claim 1, wherein the surface treatment layer is in a range of 25 μm in the observation cross section of the surface treatment layer, and the average distribution is 6 to 35 heights of 1 to 5 μm. A protrusion formed by roughening particles. The surface-treated copper foil according to claim 1, wherein a maximum width between the protrusions in the surface treatment layer is 0.01 μm or more and 25 μm divided by a protrusion existing in a range of 25 μm in the observation section. The number of the obtained is less than 2 times the length. A circuit board produced by using the surface-treated copper foil according to any one of claims 1 to 5.