WO2023190833A1 - 表面処理銅箔、銅張積層板、及びプリント配線板 - Google Patents
表面処理銅箔、銅張積層板、及びプリント配線板 Download PDFInfo
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- WO2023190833A1 WO2023190833A1 PCT/JP2023/013104 JP2023013104W WO2023190833A1 WO 2023190833 A1 WO2023190833 A1 WO 2023190833A1 JP 2023013104 W JP2023013104 W JP 2023013104W WO 2023190833 A1 WO2023190833 A1 WO 2023190833A1
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- Prior art keywords
- copper foil
- treated copper
- treated
- treatment
- contact angle
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/22—Secondary treatment of printed circuits
- H05K3/26—Cleaning or polishing of the conductive pattern
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/20—Layered products comprising a layer of metal comprising aluminium or copper
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F1/00—Etching metallic material by chemical means
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/10—Electroplating with more than one layer of the same or of different metals
- C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
- C25D5/14—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium two or more layers being of nickel or chromium, e.g. duplex or triplex layers
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/16—Electroplating with layers of varying thickness
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/06—Wires; Strips; Foils
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/03—Use of materials for the substrate
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/03—Use of materials for the substrate
- H05K1/0313—Organic insulating material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2311/00—Metals, their alloys or their compounds
- B32B2311/12—Copper
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2457/00—Electrical equipment
- B32B2457/08—PCBs, i.e. printed circuit boards
Definitions
- the present invention relates to a surface-treated copper foil that can be suitably used for manufacturing printed wiring boards and the like, as well as a copper-clad laminate and a printed wiring board using the surface-treated copper foil.
- the etching factor determined from the bottom width, top width, and height of the circuit has been widely used as an index to express circuit processability, but in addition to this, the angle of the tangent at the bottom edge of the circuit is also important. I've come to understand.
- the angle of the tangent at the bottom edge of the circuit is small (i.e., the bottom width is larger than the top width of the circuit, and the cross section of the circuit is When viewed from a microscopic perspective, migration may occur, which is expected to be caused by poor etching at the interface at the edge of the circuit, resulting in a widened shape, and the angle of the tangent at the bottom edge of the circuit may occur. The smaller the value, the more likely migration was to occur.
- An object of the present invention is to provide a surface-treated copper foil, a copper-clad laminate, and a printed wiring board that have excellent circuit workability and are less likely to generate transmission loss or foreign matter.
- a surface-treated copper foil according to one embodiment of the present invention is a surface-treated copper foil having a copper foil base and a surface treatment layer formed on at least one surface of the copper foil base, wherein the surface treatment layer is rough. Consisting of one or both of a chemical treatment layer and a rust prevention treatment layer, when the optical roughness of the surface of the surface treatment layer is measured in accordance with the method specified in ISO 25178, the arithmetic mean roughness Sa is 0.04 ⁇ m or more 0.30 ⁇ m or less, and after laminating the resin member on the surface treatment layer of the surface-treated copper foil, the surface-treated copper foil is removed by etching, and the surface-treated copper foil of the remaining resin member is pasted.
- the contact angle ⁇ 1 of distilled water was measured in accordance with the sessile drop method specified in JIS R3257:1999 on the transfer surface, which is a surface treated with surface treated copper foil.
- the contact angle ⁇ 0 of distilled water is measured according to the sessile drop method on the non-transfer surface to which the foil is later bonded, the difference between the contact angle ⁇ 0 and the contact angle ⁇ 1 is ⁇ 0 - ⁇
- the gist is that 1 is between 5° and 35°.
- a copper-clad laminate according to another aspect of the present invention includes the surface-treated copper foil according to the above-mentioned one aspect and a resin base material laminated on the surface-treated layer of the surface-treated copper foil. do.
- a printed wiring board according to yet another aspect of the present invention includes the surface-treated copper foil according to the other aspect.
- the circuit processability is excellent, and transmission loss and foreign matter are less likely to occur.
- FIG. 1 is a cross-sectional view illustrating the configuration of a surface-treated copper foil according to an embodiment of the present invention. It is a figure explaining the wettability of the transfer surface of a resin base material.
- FIG. 1 is a diagram illustrating a method for manufacturing a copper-clad laminate and a printed wiring board according to an embodiment of the present invention.
- the surface-treated copper foil 30 and the resin base material 40 are bonded together to produce the copper-clad laminate 50 (see (b) in FIG. 3), and There is an etching process (see FIG. 3C) in which unnecessary portions of the surface-treated copper foil 30 of the stretched laminate 50 other than the portions that will become the circuits 31 are removed by etching using an etching solution.
- the resin base material 40 is bonded onto the surface-treated layer 20 of the surface-treated copper foil 30 (see (a) in FIG. 3).
- the surface to which the surface-treated copper foil 30 was bonded has the shape of the surface 20a of the surface-treated layer 20 of the surface-treated copper foil 30 that had been bonded. is transcribed. That is, the surface of the resin base material 40 to which the surface-treated copper foil 30 was bonded serves as a transfer surface (replica) 40a of the surface of the surface-treated copper foil 30 that was bonded.
- the surface roughness of the surface-treated copper foil 30 decreases, the surface roughness of the transfer surface 40a of the resin base material 40 also decreases, and the wettability of the transfer surface 40a decreases. It became clear that this would happen. If the wettability of the surface of the resin base material 40 is low, the ends of the circuits 31 (surface-treated copper foil 30 remaining after etching) on the resin base material 40 during etching (the ends of the circuits 31 in the wiring width direction) Since it becomes difficult for the etching solution to reach all the areas, it is thought that circuit workability deteriorates. Whether the etching solution reaches the end of the circuit 31 depends particularly on the workability of the bottom end 31b of the circuit 31 (the part of the end of the circuit 31 adjacent to the resin base material 40 (see FIG. 2)). It is an important element for
- the present inventors have revealed that when the surface wettability of the resin base material 40 is low, foreign matter 100 is likely to be formed on the printed wiring board 60.
- the foreign matter 100 includes deposits that had adhered to the surface-treated copper foil 30 or the resin base material 40 before bonding, solidified salts contained in the etching solution, and the like.
- the present inventors have found that the wettability of the transfer surface 40a of the resin base material 40 after the etching process is a very important factor in manufacturing the printed wiring board 60.
- the present invention also shows that the wettability of the transfer surface 40a of the resin base material 40 after the etching process can be evaluated by the contact angle of distilled water measured in accordance with the sessile drop method specified in JIS R3257:1999. They found out.
- the surface-treated copper foil 30 is a surface-treated copper foil 30 having a copper foil base 10 and a surface treatment layer 20 formed on at least one surface of the copper foil base 10,
- the surface treatment layer 20 consists of one or both of a roughening treatment layer 21 and a rust prevention treatment layer 22 (see FIG. 1).
- the surface treatment layer 20 is formed only on one side of the copper foil base 10, and the surface treatment layer 20 is a surface treated copper consisting of both the roughening treatment layer 21 and the rust prevention treatment layer 22.
- An example of foil 30 is shown.
- the arithmetic mean roughness Sa is 0.04 ⁇ m or more and 0.30 ⁇ m or less. be.
- a resin base material 40 (a "resin member” which is a component of the present invention) used when manufacturing the copper clad laminate 50 or the printed wiring board 60 is added. After bonding the surface-treated copper foil 30 (corresponding to The contact angle of distilled water on the transfer surface (also referred to as ⁇ 1 ) is measured.
- the transfer surface 40a of the resin base material 40 is the surface of the resin base material 40 to which the surface-treated copper foil 30 was bonded.
- the contact angle of distilled water ⁇ 0 (hereinafter referred to as "contact angle of distilled water on the non-transfer surface before bonding the copper foil ⁇ 0 ”) is measured.
- the non-transfer surface of the resin substrate 40 is the surface of the resin substrate 40 before being bonded to the surface-treated copper foil 30, to which the surface-treated copper foil 30 will be bonded later.
- the contact angles ⁇ 0 and ⁇ 1 of distilled water are measured according to the sessile drop method specified in JIS R3257:1999.
- the difference ⁇ 0 ⁇ 1 between the contact angle ⁇ 0 and the contact angle ⁇ 1 is 5° or more and 35° or less.
- the difference ⁇ 0 ⁇ 1 between the contact angle ⁇ 0 and the contact angle ⁇ 1 is a measure of how much the wettability of the surface of the resin has changed due to bonding with the copper foil.
- the transfer surface 40a of the resin base material 40 used for manufacturing the copper-clad laminate 50 or printed wiring board 60 will be wettability increases. Therefore, the obtained copper-clad laminate 50 and printed wiring board 60 have excellent circuit processability in addition to being less likely to cause transmission loss. 40 and another resin base material 41 laminated later for manufacturing the printed wiring board 60, foreign matter is less likely to occur.
- the contact angle difference ⁇ 0 ⁇ 1 within the above numerical range, the wettability of the surface of the resin base material 40 is maintained well, so that the circuit 31 on the resin base material 40 during etching is
- the etching liquid easily spreads to the bottom end 31b of the resin base material 40, and the cleaning liquid easily spreads over the entire surface of the resin base material 40 in the cleaning process after the etching process.
- the surface-treated copper foil 30 according to this embodiment can be suitably used for manufacturing copper-clad laminates, printed wiring boards, and the like. That is, the copper-clad laminate 50 according to the present embodiment includes the surface-treated copper foil 30 according to the present embodiment and the resin base material 40 bonded on the surface-treated layer 20 of the surface-treated copper foil 30. Be prepared. Moreover, the printed wiring board 60 according to this embodiment includes the copper-clad laminate 50 according to this embodiment.
- the surface-treated copper foil 30, the copper-clad laminate 50, and the printed wiring board 60 according to this embodiment will be explained in more detail.
- the copper foil base 10, which is the raw material for the surface-treated copper foil 30 according to the present embodiment has two surfaces with ten points before being subjected to a treatment such as roughening treatment on the surface. It is preferable that the average roughness Rzjis is 2 ⁇ m or less in all cases. This ten-point average roughness Rzjis can be measured using a contact surface roughness measuring machine according to the method specified in JIS B0601:2001.
- the thickness of the copper foil base 10 before performing a treatment such as roughening treatment is 5 ⁇ m or more and 40 ⁇ m or less, although it depends on the target value of the thickness of the copper foil base 10 after the roughening treatment. It is preferable.
- the surface treatment one or both of a roughening treatment to roughen the surface and a rust prevention treatment are performed. That is, the surface treatment layer 20 consists of one or both of a roughening treatment layer 21 formed by a roughening treatment and a rust prevention treatment layer 22 formed by a rust prevention treatment.
- the surface treatment layer 20 consists of both the roughening treatment layer 21 and the rust prevention treatment layer 22, the roughening treatment layer 21 is formed on the surface of the copper foil base 10, and the rust prevention treatment layer 22 is formed on it.
- a chemical adhesive treatment using a chemical adhesive such as a silane coupling agent is performed to form a chemical adhesive layer such as a silane coupling agent layer on the rust prevention treatment layer 22. It's okay.
- At least one surface of the copper foil base 10 is treated before or after the general roughening treatment for the purpose of improving the above-mentioned wettability. Perform unevenness forming treatment. Then, a roughened layer 21 is formed by these general roughening treatments and unevenness forming treatments.
- This unevenness forming process is a process of forming minute unevenness on the surface of the copper foil base 10 to the extent that it does not affect transmission loss. Examples of this unevenness forming treatment include capsule plating treatment and etching unevenness treatment.
- Capsule plating treatment is performed before general roughening treatment. Fine unevenness is formed on the surface of the copper foil base 10 by applying smooth copper plating (capsule plating) to the surface of the copper foil base 10 using a mesh cathode shielding plate. By using a mesh cathode shielding plate, it is possible to form an uneven shape with uniform variations on the surface of the copper foil base 10.
- the plating conditions such as the aperture ratio of the mesh-like cathode shielding plate, current density, and current application time
- a fine uneven shape that does not affect transmission loss is created on the surface of the copper foil substrate 10.
- the wettability of the transfer surface 40a of the resin base material 40 can be well controlled.
- the material for forming the cathode shielding plate is preferably a material having chemical resistance and insulation properties, such as resins such as vinyl chloride, polyethylene, and polybutylene terephthalate.
- the opening area of the mesh portion is preferably 1 ⁇ m 2 or more and 100 ⁇ m 2 or less, more preferably 10 ⁇ m 2 or more and 100 ⁇ m 2 or less. Further, the aperture ratio of the mesh portion is preferably 5% or more and 15% or less.
- the aperture area and aperture ratio are within the above numerical ranges, it is possible to form a fine uneven shape on the surface of the copper foil base 10 that does not affect transmission loss, and the transfer surface of the resin base 40 can be formed on the surface of the copper foil base 10.
- the wettability of 40a is improved.
- the etching unevenness treatment is performed after the general roughening treatment and before the rust prevention treatment.
- chemically resistant rust-preventing metals such as nickel (Ni) and cobalt (Co) are electrodeposited under conditions of high current density and extremely short time, and then immersed in an etching solution for a short time.
- etching fine irregularities are formed on the surface of the copper foil base 10.
- a general electrolytic bath containing nickel sulfate, nickel sulfamate, etc. can be used for electrodeposition of nickel.
- the current density can be, for example, 1.0 A/dm 2 or more
- the current application time can be, for example, 0.5 seconds or more and 2.0 seconds or less.
- the rust preventive metal is electrodeposited only on the tops of the roughened particles formed by general roughening treatment. Therefore, a region of the surface of the copper foil base 10 other than the tops of the roughened particles is etched, and a fine uneven shape is formed in a region of the surface of the copper foil base 10 other than the tops of the roughened particles. Furthermore, by controlling conditions such as the immersion time in the etching solution, it is possible to form a fine uneven shape on the surface of the copper foil base 10 that does not affect transmission loss. As a result, the wettability of the transfer surface 40a of the resin base material 40 can be well controlled.
- etching solution for example, a common copper etching solution such as a mixture of sulfuric acid and hydrogen peroxide or hydrochloric acid can be used.
- the immersion time in the etching solution can be, for example, 2 seconds or more and 10 seconds or less. If the immersion time in the etching solution is within the above numerical range, it is possible to form a fine uneven shape on the surface of the copper foil substrate 10 that does not affect transmission loss, and transfer the resin substrate 40.
- the surface of the copper foil substrate 10 can be uniformly treated in the subsequent rust prevention treatment and chemical adhesive treatment process, resulting in good adhesion and Can provide corrosion resistance.
- a copper foil base 10 having a surface that improves the wettability of the transfer surface 40a of the bonded resin base material 40 can be obtained.
- the wettability of the transfer surface 40a of the resin base material 40 can be evaluated by the contact angle of distilled water measured according to the sessile drop method.
- the difference ⁇ 0 ⁇ 1 between the distilled water contact angle ⁇ 0 and the distilled water contact angle ⁇ 1 of the transfer surface 40a after copper foil etching must be 5° or more and 35° or less.
- the arithmetic mean roughness Sa is 0.020 ⁇ m or more and 0.070 ⁇ m or less
- the volume of the space in the core portion Vvc is It is preferably 0.030 mL/m 2 or more and 0.110 mL/m 2 or less.
- the arithmetic mean roughness Sa of the transfer surface 40a and the volume Vvc of the space in the core portion are within the above numerical ranges, even if the surface roughness of the surface treatment layer 20 of the surface treated copper foil 30 is small, the transfer surface 40a will not become wet. In addition to better properties, the processed shape of the circuit can be maintained even better. The reason for this is not clear, but it is thought that it is because the amount of etching at the resin-copper foil interface can be well controlled.
- the arithmetic mean roughness Sa is 0.020 ⁇ m or more and 0.051 ⁇ m or less
- the volume of the space in the core portion Vvc is More preferably, it is 0.030 mL/m 2 or more and 0.071 mL/m 2 or less. If the arithmetic mean roughness Sa of the transfer surface 40a and the volume Vvc of the space in the core portion are within the above numerical ranges, the generation of foreign matter can be further suppressed. Although the reason for this is not clear, it is thought that it is possible to limit the gap into which foreign matter can enter.
- the surface-treated copper according to the present embodiment is A foil 30 is obtained.
- the surface roughness of the surface treated layer 20 of the obtained surface treated copper foil 30 needs to be as follows. That is, when the optical roughness of the surface 20a of the surface treatment layer 20 is measured according to the method specified in ISO25178, the arithmetic mean roughness Sa needs to be 0.04 ⁇ m or more and 0.30 ⁇ m or less.
- the arithmetic mean roughness Sa of the surface 20a of the surface treatment layer 20 is preferably 0.04 ⁇ m or more and 0.20 ⁇ m or less, and 0.04 ⁇ m or more and 0.150 ⁇ m or less. is more preferable.
- the surface-treated copper foil 30 according to the present embodiment can be manufactured by performing the following steps (1) to (5) in the order described.
- an unevenness forming process is performed for the purpose of improving wettability, but there are two specific examples: an example using a capsule plating process and an example using an etching unevenness process as an uneven forming process. Let me explain with an example.
- the smooth and shiny surface is the shiny surface (S surface).
- the smooth and glossy surfaces are both the shiny side and the matte side (M side), but the smoother and glossier side is the matte side.
- Capsule plating treatment is performed for the purpose of improving wettability, and a fine uneven shape is formed on at least one surface of the copper foil base 10.
- the contents of the capsule plating process are as described above, but by using a mesh cathode shielding plate, the surface of the copper foil base 10 can be partially plated with copper (capsule plating). Specific examples of the composition of the plating solution and plating conditions are shown below.
- smooth copper plating (capsule plating) is applied only to the openings of the mesh portion. As a result, fine irregularities can be formed without changing the surface roughness of the entire surface of the copper foil.
- the roughening treatment it is preferable to perform, for example, a two-step plating treatment as shown below. Note that, if necessary, the second-stage fixed plating process may not be performed.
- the first step of the roughening plating process is a process of forming roughening particles on the surface of the copper foil base 10 that has been subjected to the capsule plating process.
- the first step of roughening plating treatment can be performed, for example, by plating treatment using a copper sulfate bath. Specific examples of the composition of the plating solution and plating conditions are shown below.
- the copper sulfate bath contains molybdenum (Mo), arsenic (As), antimony (Sb), bismuth (Bi), selenium (Se), tellurium ( Additives containing Te), tungsten (W), etc. may be added, and it is particularly preferable to add additives containing molybdenum.
- composition of plating solution Concentration of copper sulfate pentahydrate...5 to 15 g/L in terms of copper (atoms) Concentration of sulfuric acid...120-250g/L Concentration of ammonium molybdate...500 to 1000 mg/L in terms of molybdenum (atoms)
- the second-stage fixed plating process is a process in which smooth cover plating is performed on the copper foil base 10 that has been subjected to the first-stage roughening plating process. As a result, a roughened layer 21 is formed on the surface of the copper foil base 10.
- the second-stage fixed plating treatment can be performed, for example, by plating treatment using a copper sulfate bath. Specific examples of the composition of the plating solution and plating conditions are shown below.
- this fixed plating treatment is performed to prevent the roughening particles from falling off, that is, to fix the roughening particles.
- this fixed plating treatment is applied to the roughened surface. , it is possible to prevent the roughening particles from falling off.
- a silane coupling agent layer may be further formed on the roughening treatment layer 21 directly or via an intermediate layer.
- the intermediate layer include a base layer containing nickel, a heat-resistant treated layer containing zinc (Zn), and an anti-corrosion treated layer 22 containing chromium (Cr). Note that since the intermediate layer and the silane coupling agent layer are very thin, they do not affect the particle shape of the roughened particles on the roughened surface of the surface-treated copper foil 30.
- the particle shape of the roughened particles on the roughened surface of the surface-treated copper foil 30 is substantially determined by the particle shape of the roughened particles on the surface of the roughened layer 21 corresponding to the roughened surface.
- the base layer is preferably formed of at least one selected from nickel, nickel-phosphorus (P), nickel-zinc, and nickel-molybdenum.
- the heat-resistant treatment layer is preferably formed when it is necessary to improve the heat resistance of the surface-treated copper foil 30.
- the heat-resistant treatment layer is preferably formed of, for example, zinc or an alloy containing zinc.
- alloys containing zinc include zinc-tin (Sn) alloy, zinc-nickel alloy, zinc-cobalt alloy, zinc-copper alloy, zinc-molybdenum alloy, zinc-chromium alloy, and zinc-vanadium (V) alloy. It will be done.
- the anticorrosion treatment layer 22 it is preferable to form the anticorrosion treatment layer 22 when it is necessary to further improve corrosion resistance.
- the antirust layer 22 include a chromium layer formed by chromium plating and a chromate layer formed by chromate treatment. When forming all three layers, the base layer, the heat-resistant treatment layer, and the rust prevention treatment layer 22, it is preferable to form them on the roughening treatment layer 21 in this order. Further, depending on the use and desired characteristics, only one or two of the base layer, heat-resistant treatment layer, and rust-prevention treatment layer 22 may be formed.
- silane coupling agent layer As a method for forming the silane coupling agent layer, for example, silane coupling is performed on the uneven surface of the roughening treatment layer 21 of the surface-treated copper foil 30 directly or through an intermediate layer. After applying a solution of the agent, air drying (natural drying) or heating drying may be used. When the water in the applied coupling agent solution evaporates, a silane coupling agent layer is formed. Drying by heating at a temperature of 50 to 180°C is preferable because the reaction between the silane coupling agent and the copper foil is accelerated.
- the silane coupling agent layer includes an epoxy silane coupling agent, an amino silane coupling agent, a vinyl silane coupling agent, a methacrylic silane coupling agent, an acrylic silane coupling agent, an azole silane coupling agent, and a styryl silane coupling agent. It is preferable to contain at least one of a silane coupling agent, a ureide silane coupling agent, a mercapto silane coupling agent, a sulfide silane coupling agent, and an isocyanate silane coupling agent.
- Example using etching unevenness treatment (1) Manufacture of copper foil substrate This is the same as in the case of using capsule plating treatment. (2) Formation of roughening treatment layer This is the same as in the case of using capsule plating treatment.
- Etching unevenness treatment For the purpose of improving wettability, etching unevenness treatment is performed to form fine unevenness on the surface of the copper foil base 10.
- the contents of the etching unevenness treatment are as described above, but the treatment conditions and the like will be explained in more detail.
- Electrodeposition was carried out using an electrolytic bath containing nickel sulfate and having a nickel concentration of 30 to 150 g/L, with a current density of 1.0 to 4.0 A/dm 2 and a current application time of 0.5 to 2.0 seconds. By performing etching by immersing it in an etching solution for a short time and then etching it, it is possible to form a fine uneven shape on the surface of the copper foil base 10 that does not affect transmission loss.
- etching unevenness process forms unevenness on the surface of the roughened particles formed by the roughening process
- other etching methods include etching in a solution containing an inorganic acid such as hydrochloric acid, sulfuric acid, or phosphoric acid.
- An example is immersion treatment.
- an aqueous inorganic acid solution of a predetermined concentration for about several seconds to several tens of seconds, fine irregularities are formed on the surface of the roughened particles.
- hydrochloric acid fine irregularities are formed on the surface of the roughened particles by immersing them in hydrochloric acid with a concentration of 5 to 20% by volume for 2 seconds or more.
- etching methods include, in addition to the above-mentioned immersion treatment in a solution containing an inorganic acid, immersion treatment in a solution containing an organic acid such as acetic acid or formic acid, or a solution containing iron chloride or copper chloride. It is also possible to use immersion treatment and electrolytic etching treatment using anodic oxidation. These methods may be used in combination of two or more.
- the wettability of the transfer surface 40a of the resin base material 40 bonded to the surface-treated copper foil 30 when manufacturing the copper-clad laminate 50 or the printed wiring board 60 is based on the sessile drop method specified in JIS R3257:1999. It can be evaluated by the contact angle of distilled water measured as follows.
- the contact angle ⁇ 0 of distilled water is measured on the surface to which the surface-treated copper foil 30 is bonded later based on the sessile drop method described above. do.
- the surface on which the distilled water contact angle ⁇ 0 of the non-transfer surface before the copper foil bonding was measured is the non-transfer surface to which the shape of the surface of the surface-treated copper foil 30 has not been transferred.
- the surface-treated copper foil 30 is removed by etching, and the surface-treated part of the surface of the remaining resin base material 40 is Regarding the surface to which the copper foil 30 was bonded, the contact angle ⁇ 1 of distilled water is measured according to the sessile drop method described above.
- the surface on which the distilled water contact angle ⁇ 1 of the transfer surface after copper foil etching was measured is the transfer surface 40a to which the shape of the surface of the bonded surface-treated copper foil 30 is transferred.
- the wettability of the transfer surface 40a of the resin base material 40 is evaluated based on the difference ⁇ 0 ⁇ 1 between the contact angle ⁇ 0 and the contact angle ⁇ 1 . If the difference ⁇ 0 ⁇ 1 between the contact angle ⁇ 0 and the contact angle ⁇ 1 is 5° or more and 35° or less, the wettability of the transfer surface 40a is good.
- the resin member used when measuring the contact angle ⁇ 0 and the contact angle ⁇ 1 is of the same type as the resin base material 40 used when manufacturing the copper-clad laminate 50 and the printed wiring board 60, as described above. However, different ones may be used to measure the contact angle ⁇ 0 and the contact angle ⁇ 1 . That is, a member having a different resin type, shape, size, etc. from the resin base material 40 used when manufacturing the copper-clad laminate 50 or the printed wiring board 60 may be used as the resin member.
- the type of resin forming the resin member used when measuring the contact angle ⁇ 0 and the contact angle ⁇ 1 may be a curable resin such as a thermosetting resin, or a thermoplastic resin.
- the contact angle ⁇ 0 and the contact angle ⁇ 1 are measured after the resin member is cured. That is, in the case of a contact angle ⁇ 1 , the uncured resin member is bonded onto the surface treated layer 20 of the surface treated copper foil 30, and after the resin member is cured, the surface treated copper foil 30 is removed by etching. do. Then, the contact angle ⁇ 1 of distilled water is measured on the transfer surface of the resin member according to the sessile drop method described above.
- the structure of the copper-clad laminate 50 according to the present embodiment is not particularly limited, but includes a surface-treated copper foil 30 and a resin base material 40.
- the resin base material 40 is bonded onto the surface treated layer 20 of the surface treated copper foil 30.
- This copper-clad laminate 50 can be used, for example, to manufacture a printed wiring board 60.
- examples of the resin forming the resin base material 40 include epoxy resin, polyphenylene ether, phenol resin, bis(phenoxyphenoxy)benzene, polyimide, liquid crystal polymer, and fluororesin (eg, polytetrafluoroethylene).
- the configuration of the printed wiring board 60 according to the present embodiment is not particularly limited, it includes the copper-clad laminate 50 according to the present embodiment.
- the printed wiring board 60 can be obtained by bonding another resin base material 41 to cover the circuit 31. (See Figure 3(d)).
- the resin base material 41 bonded together to cover the circuit 31 may be of the same type as the resin base material 40 of the copper-clad laminate 50, or may be of a different type.
- the present invention will be explained in more detail by showing Examples and Comparative Examples below.
- the surface-treated copper foil of Comparative Example 7 was manufactured by the manufacturing method described in Patent Document 1.
- the surface-treated copper foil of Comparative Example 8 was manufactured by the manufacturing method described in Patent Document 2
- the surface-treated copper foil of Comparative Example 9 was manufactured by the manufacturing method described in Patent Document 3.
- the surface-treated copper foil of Comparative Example 10 was manufactured by the manufacturing method described in Patent Document 4, and the surface-treated copper foil of Comparative Example 11 was manufactured by the manufacturing method described in Patent Document 5. It is something.
- Examples 1 to 23 and Comparative Examples 1 to 6 and 12 to 14 were manufactured by the procedure described below.
- the cathode used to produce the electrolytic copper foil was a titanium rotating drum whose surface roughness was adjusted by buffing to #1000 to #2000, and the anode was a dimensionally stable anode DSA (registered trademark).
- DSA registered trademark
- the copper foil substrate produced as described above was subjected to the general roughening treatment described above and an unevenness forming treatment for the purpose of improving wettability.
- the copper foil substrate was subjected to capsule plating treatment, which is an unevenness forming treatment for the purpose of improving wettability.
- a roughening treatment was applied.
- the copper foil substrate was subjected to a general roughening treatment, and then subjected to an etching unevenness treatment, which is an unevenness forming treatment for the purpose of improving wettability. did.
- General roughening treatment, capsule plating treatment, and etching unevenness treatment will be explained below.
- ⁇ Composition of the plating solution for the first stage electroplating process Concentration of copper sulfate pentahydrate...10g/L in terms of copper (atoms) Concentration of sulfuric acid...150g/L Concentration of ammonium molybdate...600mg/L in terms of molybdenum (atoms) ⁇ Conditions for first stage electroplating treatment> Processing speed: 15 m/min Current density: 15 to 55 A/dm 2 Bath temperature...15°C Energization time...4 to 6 seconds
- Capsule plating treatment which is an unevenness forming treatment, was performed on the copper foil substrate using a roll-to-roll method.
- Tables 1 and 2 copper foil substrates having different surface irregularities were obtained by changing the aperture ratio of the cathode shielding plate, the current density of electroplating, and the current application time.
- Etching unevenness treatment which is an unevenness forming process, was performed on the roughened surface of the copper foil substrate that had been subjected to the roughening treatment.
- the etching unevenness process is a process in which nickel is electrodeposited and then immersed in an etching solution for etching.
- the composition of the electrolytic solution used for electrodeposition, conditions for electrodeposition, and conditions for etching are shown below. As shown in Tables 1 and 2, copper foil substrates having different surface irregularities were obtained by changing the current density and current application time of electrodeposition, and the processing time of etching.
- the rust prevention treatment is a treatment in which nickel plating, zinc plating, and chrome plating are applied in this order. Conditions for nickel plating, zinc plating, and chrome plating are shown.
- silane coupling agent treatment was performed to form a silane coupling agent layer on the outermost chromium plating layer of the rust prevention treatment layer.
- the silane coupling agent layer was formed by applying a 3-aminopropyltrimethoxysilane aqueous solution having a concentration of 0.2% by mass and drying at 100°C.
- Example 21 and Comparative Example 12 ThunderClad 3+ manufactured by Taiwan Union Corporation was used, and for Example 22 and Comparative Example 13, Espanex (registered trademark) manufactured by Nippon Steel Chemical & Materials Co., Ltd. was used.
- Example 23 and Comparative Example 14 liquid crystal polymer film Vector (registered trademark) manufactured by Kuraray Co., Ltd. was used. Note that the surface-treated copper foil and the resin member were bonded together under conditions that conformed to the process guidelines for each resin.
- This copper-clad laminate was etched using a mixed solution of cupric chloride and hydrochloric acid as an etching solution to remove all the surface-treated copper foil. After thoroughly washing the remaining resin member with water, the contact angle ⁇ 1 of distilled water was measured using the sessile drop method specified in JIS R3257:1999 on the surface of the resin member to which the surface-treated copper foil was bonded (transfer surface). Measured according to.
- a resin member of the same type as the resin member bonded on the surface treatment layer of the surface-treated copper foil is separately prepared, and the surface-treated copper foil is not bonded to the other resin member.
- An operation similar to the above procedure for producing a stretched laminate was performed, and the contact angle ⁇ 0 of distilled water on the surface (non-transfer surface) was measured according to the sessile drop method described above. Then, the difference ⁇ 0 ⁇ 1 between the contact angle ⁇ 0 and the contact angle ⁇ 1 was calculated.
- the arithmetic mean roughness Sa and core space volume Vvc were measured using confocal laser microscopes VK-X1050 and VK-X1000 manufactured by Keyence Corporation in accordance with ISO25178.
- the magnification of the objective lens of the confocal laser microscope is 100 times, the scan mode is laser confocal, the measurement size is 2048 x 1536, the measurement quality is High Precision, and the pitch is 0.08 ⁇ m. Further, calculations of the arithmetic mean roughness Sa and the volume Vvc of the space in the core portion were performed under the filter processing and calculation conditions shown below.
- ⁇ Circuit processability> A resist pattern with an L&S of 50/50 ⁇ m was placed on a surface-treated copper foil of a copper-clad laminate similar to the one prepared to measure the distilled water contact angle ⁇ 1 of the transfer surface after copper foil etching using the subtractive method. It was formed by The surface-treated copper foil was then etched to form a circuit having a wiring pattern. A dry resist film was used as the resist, and a mixed solution containing copper chloride and hydrochloric acid was used as the etching solution.
- the etching factor (Ef) of the obtained circuit was measured.
- the copper-clad laminate on which the circuit was formed was cut to obtain a cross section perpendicular to the surface of the resin member, and the cross section of the circuit was observed using a scanning electron microscope.
- angles X and Y on the cross section shown in FIG. 2 were measured.
- the angle X is the angle between the straight line connecting the top end 31a and bottom end 31b of the circuit 31 and the surface of the resin member.
- the angle Y is the angle between the tangent to the bottom end 31b of the circuit 31 and the surface of the resin member.
- the tangent to the bottom end 31b of the circuit 31 will be defined in more detail. Draw a straight line parallel to the surface of the resin member at a height of 1.5 ⁇ m from the bottom surface of the resin member, and connect the intersection 31c of the straight line with the side surface of the circuit 31 to the bottom end 31b. A straight line is defined as "a tangent to the bottom end 31b of the circuit 31", and an angle between this tangent and the surface of the resin member is defined as an angle Y.
- a printed wiring board with a strip line formed thereon was fabricated using a copper-clad laminate similar to the one fabricated to measure the distilled water contact angle ⁇ 1 on the transfer surface after copper foil etching, and the transmission characteristics were evaluated. .
- the circuit width of the strip line formed on this printed wiring board was 140 ⁇ m, and the circuit length was 76 mm.
- a copper-clad laminate similar to the one prepared to measure the distilled water contact angle ⁇ 1 of the transfer surface after copper foil etching was etched using a mixture of cupric chloride and hydrochloric acid as the etching solution. All treated copper foil was removed. After thoroughly washing the remaining resin member with water, apply a resin member of the same type as that used to make the above-mentioned copper-clad laminate to the surface of the resin member to which the surface-treated copper foil was bonded (transfer surface). and the surface-treated copper foil were laminated in this order and then etched in the same manner as above to remove all the surface-treated copper foil. As a result, a resin sample made of two resin members bonded together was obtained.
- the obtained resin sample was cut into a square shape of 5 cm on each side. Then, the cut resin sample was observed with a microscope at a magnification of 35 times, and the number of black spots with a diameter of 1 mm or more was measured. These black spots are caused by foreign matter generated between the two resin members bonded together. Observation using a microscope was performed by viewing the transfer surface of the resin member that originally constituted the copper-clad laminate from the side of the resin member that was later bonded. The results are shown in Tables 1 and 2. In Tables 1 and 2, if the number of black dots per cut resin sample is 2 or less, it is marked "A”, if it is 3 or more and 5 or less, it is marked "B", and if it is more than 5, it is marked "B". is indicated as "C”.
- the arithmetic mean roughness Sa of the surface of the surface treatment layer was controlled within a range of 0.04 ⁇ m to 0.30 ⁇ m. Regardless, the difference ⁇ 0 - ⁇ 1 between the contact angle ⁇ 0 and the contact angle ⁇ 1 , which represents the wettability of the transfer surface of the resin base material, is well controlled, resulting in excellent circuit processability and low transmission loss and Foreign matter was less likely to occur.
- the surface-treated copper foils of Examples 1 to 4, 10 to 14, 17, 18, and 21 to 23 have the arithmetic mean roughness Sa of the transfer surface of the resin base material and the volume of the space in the core part Vvc. Since it was well controlled, the circuit processability was even better and the generation of foreign matter was further reduced.
- the surface-treated copper foils of Comparative Examples 1 to 14 have low wettability on the transfer surface of the resin base material, and therefore have poor circuit processability, transmission loss, and generation of foreign matter. That was enough.
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Abstract
Description
また、プリント配線板の高密度実装化、多機能化に伴い、回路の微細配線化も進んでいる。微細配線を形成するために回路加工性が良好な表面処理銅箔が求められており、回路加工性を向上させるために、表面を低粗度とすることが検討されている(例えば特許文献2を参照)。また、その他にも、銅箔を表面処理する金属の工夫(例えば特許文献3を参照)や、樹脂の表面へ転写した凹凸の形状の工夫(例えば特許文献4、5を参照)などの要因が検討されている。
本発明は、回路加工性に優れるとともに伝送損失及び異物の発生が生じにくい表面処理銅箔、銅張積層板、及びプリント配線板を提供することを課題とする。
本発明のさらに別の態様に係るプリント配線板は、上記別の態様に係る表面処理銅箔を備えることを要旨とする。
上記課題を解決するため、本発明者らは、銅張積層板やプリント配線板を製造する際に使用する樹脂製基材の表面の濡れ性に着目し、鋭意研究を行った。図1、2、3を参照しながら、以下に詳細に説明する。
そして、表面処理銅箔30の表面処理層20の表面20aの光学式粗さをISO25178に規定の方法に準拠して測定した場合に、算術平均粗さSaは0.04μm以上0.30μm以下である。
(A)表面処理銅箔について
本実施形態に係る表面処理銅箔30の原料である銅箔基体10は、粗化処理等の処理を表面に対して施す前の時点において、2面の十点平均粗さRzjisがいずれも2μm以下であることが好ましい。この十点平均粗さRzjisは、JIS B0601:2001に規定された方法に従って、接触式表面粗さ測定機を用いて測定することができる。表面の十点平均粗さRzjisが2μm以下であれば、樹脂製基材40との密着力が良好となりやすい。
また、粗化処理等の処理を施す前の時点での銅箔基体10の厚さは、粗化処理後の銅箔基体10の厚さの目標値次第ではあるが、5μm以上40μm以下であることが好ましい。
ニッケルの電析には、硫酸ニッケル、スルファミン酸ニッケル等を含有する一般的な電解浴を用いることができる。また、電流密度は例えば1.0A/dm2以上、通電時間は例えば0.5秒以上2.0秒以下とすることができる。
また、エッチング液への浸漬時間等の条件を制御することによって、伝送損失に影響を与えない程度の微細な凹凸形状を銅箔基体10の表面に形成することができる。その結果、樹脂製基材40の転写表面40aの濡れ性を良好にコントロールすることができる。
(1)銅箔基体の製造
本実施形態に係る表面処理銅箔30の製造においては、粗大な凹凸が存在しない平滑で光沢のある表面を有する電解銅箔や圧延銅箔を、銅箔基体10として用いることが好ましい。中でも、生産性やコストの観点で電解銅箔を用いることが好ましく、特に、「両面光沢箔」と一般的に呼称されている両面が平滑な電解銅箔を用いることがより好ましい。
濡れ性の向上を目的としてカプセルめっき処理を行い、銅箔基体10の少なくとも一方の表面に微細な凹凸形状を形成する。カプセルめっき処理の内容は前述のとおりであるが、メッシュ状のカソード遮蔽板を用いることにより、銅箔基体10の表面に部分的に銅めっき(カプセルめっき)を施すことができる。
めっき液の組成やめっき条件の具体例を下記に示す。電流密度を適切に設定することにより、メッシュ部分の開口部のみに平滑な銅めっき(カプセルめっき)が施される。その結果、銅箔の表面全体の表面粗さを変えることなく微細な凹凸を形成することができる。
硫酸銅五水和物の濃度・・・銅(原子)換算で50~65g/L
硫酸の濃度・・・80~170g/L
<めっき処理の条件>
処理速度・・・5~18m/分
電流密度・・・1~5A/dm2
粗化処理として、例えば下記に示すような二段階のめっき処理を行うことが好ましい。なお、必要に応じて、二段階目の固定めっき処理は行わなくてもよい。
一段階目の粗化めっき処理は、銅箔基体10のカプセルめっき処理を施した表面上に粗化粒子を形成する処理である。一段階目の粗化めっき処理は、例えば硫酸銅浴を用いるめっき処理によって行うことができる。めっき液の組成やめっき条件の具体例を下記に示す。
硫酸銅五水和物の濃度・・・銅(原子)換算で5~15g/L
硫酸の濃度・・・120~250g/L
モリブデン酸アンモニウムの濃度・・・モリブデン(原子)換算で500~1000mg/L
処理速度・・・8~22m/分
電流密度・・・15~55A/dm2
処理時間・・・0.5~5.0秒
浴温・・・8~20℃
硫酸銅五水和物の濃度・・・銅(原子)換算で50~65g/L
硫酸の濃度・・・90~160g/L
<めっき処理の条件>
処理速度・・・5~20m/分
電流密度・・・1~7A/dm2
粗化処理層21の上に、直接又は中間層を介してシランカップリング剤層をさらに形成してもよい。中間層としては、ニッケルを含有する下地層、亜鉛(Zn)を含有する耐熱処理層、及びクロム(Cr)を含有する防錆処理層22等が挙げられる。なお、中間層及びシランカップリング剤層はその厚さが非常に薄いため、表面処理銅箔30の粗化面における粗化粒子の粒子形状に影響を与えるものではない。表面処理銅箔30の粗化面における粗化粒子の粒子形状は、粗化面に対応する粗化処理層21の表面における粗化粒子の粒子形状で実質的に決定される。
下地層、耐熱処理層、及び防錆処理層22の三層を全て形成する場合には、この順序で粗化処理層21上に形成することが好ましい。また、用途や目的とする特性に応じて、下地層、耐熱処理層、及び防錆処理層22のうちいずれか一層又は二層のみを形成してもよい。
シランカップリング剤層の形成方法としては、例えば、表面処理銅箔30の粗化処理層21の凹凸表面上に、直接又は中間層を介してシランカップリング剤溶液を塗布した後に、風乾(自然乾燥)又は加熱乾燥して形成する方法が挙げられる。塗布されたカップリング剤溶液中の水が蒸発すれば、シランカップリング剤層が形成される。50~180℃の温度で加熱乾燥すると、シランカップリング剤と銅箔の反応が促進されるため好適である。
(1)銅箔基体の製造
カプセルめっき処理を用いた例の場合と同様である。
(2)粗化処理層の形成
カプセルめっき処理を用いた例の場合と同様である。
濡れ性の向上を目的としてエッチング凹凸処理を行い、銅箔基体10の表面に微細な凹凸形状を形成する。エッチング凹凸処理の内容は前述のとおりであるが、処理条件等についてさらに詳細に説明する。硫酸ニッケルを含有し且つニッケル濃度が30~150g/Lである電解浴を用い、電流密度を1.0~4.0A/dm2、通電時間を0.5~2.0秒として電析を行い、その後にエッチング液に短時間浸漬してエッチングすることにより、伝送損失に影響を与えない程度の微細な凹凸形状を銅箔基体10の表面に形成することができる。
カプセルめっき処理を用いた例の場合と同様である。
(5)シランカップリング剤層の形成
カプセルめっき処理を用いた例の場合と同様である。
次に、転写表面40aの濡れ性の評価方法について説明する。銅張積層板50やプリント配線板60を製造する際に表面処理銅箔30に貼り合わせた樹脂製基材40の転写表面40aの濡れ性は、JIS R3257:1999に規定の静滴法に準拠して測定した蒸留水の接触角によって評価することができる。
そして、接触角θ0と接触角θ1との差θ0-θ1によって、樹脂製基材40の転写表面40aの濡れ性を評価する。接触角θ0と接触角θ1との差θ0-θ1が5°以上35°以下であれば、転写表面40aの濡れ性は良好である。
本実施形態に係る銅張積層板50の構成は特に限定されるものではないが、表面処理銅箔30と樹脂製基材40とを備えている。そして、樹脂製基材40は、表面処理銅箔30の表面処理層20上に貼り合わされている。この銅張積層板50は、例えばプリント配線板60の製造に使用することができる。
なお、樹脂製基材40を形成する樹脂としては、例えば、エポキシ樹脂、ポリフェニレンエーテル、フェノール樹脂、ビス(フェノキシフェノキシ)ベンゼン、ポリイミド、液晶ポリマー、フッ素樹脂(例えばポリテトラフルオロエチレン)が挙げられる。
本実施形態に係るプリント配線板60の構成は特に限定されるものではないが、本実施形態に係る銅張積層板50を備えている。例えば、銅張積層板50の表面処理銅箔30をエッチングして回路31を形成した後に、回路31を覆うように別の樹脂製基材41を貼り合わせれば、プリント配線板60を得ることができる(図3の(d)を参照)。回路31を覆うように貼り合わる樹脂製基材41は、銅張積層板50の樹脂製基材40と同種のものでもよいし、異種のものでもよい。
以下に実施例及び比較例を示して、本発明をさらに具体的に説明する。まず、比較例7の表面処理銅箔は、特許文献1に記載の製造方法によって製造したものである。以下同様に、比較例8の表面処理銅箔は、特許文献2に記載の製造方法によって製造したものであり、比較例9の表面処理銅箔は、特許文献3に記載の製造方法によって製造したものであり、比較例10の表面処理銅箔は、特許文献4に記載の製造方法によって製造したものであり、比較例11の表面処理銅箔は、特許文献5に記載の製造方法によって製造したものである。
(ア)銅箔基体
実施例1~23及び比較例1~6、12~14の表面処理銅箔を製造するための原料である銅箔基体として、厚さ18μmのロール状の電解銅箔(両面光沢箔)を作製した。電解銅箔の作製に用いたカソードは、#1000~#2000のバフ研磨により表面粗さを調整されたチタン製の回転ドラムであり、アノードは寸法安定性陽極DSA(登録商標)である。電解液の組成、電解条件を下記に示す。
銅 :75g/L
硫酸:65g/L
塩素:20mg/L
3-メルカプト-1-プロパンスルホン酸ナトリウム:2mg/L
ヒドロキシエチルセルロース :10mg/L
低分子量膠(分子量3000) :50mg/L
<電解条件>
浴温 :50℃
電流密度:45A/dm2
銅箔基体のマット面に対して、ロール・ツー・ロール方式で粗化処理を施した。この粗化処理は、二段階の電気めっき処理である。一段階目の電気めっき処理のめっき液の組成とめっき条件を下記に示す。また、二段階の電気めっき処理(固定めっき処理)のめっき液の組成とめっき条件を下記に示す。表1、2に示すように、一段階目の電気めっき処理の電流密度と通電時間を変更することによって、異なる高さ、形状を有する粗化粒子を銅箔の表面上に形成した。
硫酸銅五水和物の濃度・・・銅(原子)換算で10g/L
硫酸の濃度・・・150g/L
モリブデン酸アンモニウムの濃度・・・モリブデン(原子)換算で600mg/L
<一段階目の電気めっき処理の条件>
処理速度・・・15m/分
電流密度・・・15~55A/dm2
浴温・・・15℃
通電時間・・・4~6秒
硫酸銅五水和物の濃度・・・銅(原子)換算で55g/L
硫酸の濃度・・・120g/L
<二段階目の電気めっき処理の条件>
処理速度・・・15m/分
電流密度・・・2A/dm2
通電時間・・・3秒
銅箔基体に対して、ロール・ツー・ロール方式で、凹凸形成処理であるカプセルめっき処理を施した。開口面積が50μm2、開口率が5~15%のメッシュ状カソード遮蔽板を電解浴内の銅箔基体の近傍に設置し、下記組成のめっき液を用いて下記めっき条件で電気めっき処理を行った。表1、2に示すように、カソード遮蔽板の開口率、電気めっきの電流密度と通電時間を変更することによって、異なる表面凹凸を有する銅箔基体とした。
硫酸銅五水和物の濃度・・・銅(原子)換算で60g/L
硫酸の濃度・・・150g/L
<めっき処理の条件>
処理速度・・・18m/分
粗化処理を施した銅箔基体の粗化処理を施した面に対して、凹凸形成処理であるエッチング凹凸処理を施した。エッチング凹凸処理は、ニッケルを電析した後にエッチング液に浸漬してエッチングするという処理であるが、電析に用いた電解液の組成、電析の条件、エッチングの条件を下記に示す。表1、2に示すように、電析の電流密度と通電時間、及び、エッチングの処理時間を変更することによって、異なる表面凹凸を有する銅箔基体とした。
ニッケルの濃度・・・60g/L
ホウ酸(H3BO3)の濃度・・・15g/L
浴温・・・20℃
pH・・・3.5
電流密度・・・1~2.5A/dm2
通電時間・・・1~3秒
<エッチングの条件>
エッチング液・・・濃度10体積%の塩酸
浴温・・・30℃
処理時間・・・0.5~2秒
続いて、上記のように粗化処理及び凹凸形成処理を施した銅箔基体の該処理を施した表面に、防錆処理を施して防錆処理層を形成した。防錆処理は、ニッケルめっき、亜鉛めっき、クロムめっきを該順序で施す処理である。ニッケルめっき、亜鉛めっき、クロムめっきの条件を示す。
ニッケルの濃度・・・45g/L
ホウ酸の濃度・・・20g/L
浴温・・・20℃
pH・・・3.5
<ニッケルめっきの条件>
電流密度:0.4A/dm2
処理時間:8秒
亜鉛の濃度・・・2.5g/L
水酸化ナトリウム(NaOH)の濃度・・・25g/L
浴温・・・20℃
<亜鉛めっきの条件>
電流密度:0.7A/dm2
処理時間:4秒
クロムの濃度・・・8g/L
浴温・・・30℃
pH・・・2.4
<クロムめっきの条件>
電流密度:5A/dm2
処理時間:4秒
最後に、シランカップリング剤処理を施し、防錆処理層の最表面のクロムめっき層の上に、シランカップリング剤層を形成した。シランカップリング剤層の形成は、濃度0.2質量%の3-アミノプロピルトリメトキシシラン水溶液を塗布し、100℃で乾燥させることにより行った。
<蒸留水の接触角>
表面処理銅箔の表面処理層(すなわちシランカップリング剤層)上に樹脂製部材を貼り合わせて銅張積層板とした。樹脂製部材としては、下記の物を用いた。すなわち、実施例1~20及び比較例1~11については、樹脂製部材として、低誘電ポリフェニレンエーテル系樹脂基材フィルム(パナソニック株式会社製の超低伝送損失・高耐熱多層基板材料MEGTRON7N、厚さ60μm)を2枚重ねて貼り合わせたものを用いた。
なお、表面処理銅箔と樹脂製部材の貼り合わせは、それぞれの樹脂毎のプロセスガイドラインに則った条件で行った。
表面処理銅箔の表面処理層(すなわちシランカップリング剤層)の表面の算術平均粗さSa、及び、銅箔エッチング後の転写表面の蒸留水接触角θ1を測定した樹脂製部材の転写表面の算術平均粗さSa、コア部の空間の容積Vvcを、株式会社キーエンス製の共焦点レーザー顕微鏡VK-X1050及びVK-X1000を用いて、ISO25178に従って測定した。
また、算術平均粗さSa、コア部の空間の容積Vvcの演算は、以下に示すフィルター処理及び演算条件で行った。
Sフィルター:無し
F-operation:平面傾き補正
Lフィルター:0.025μm
演算対象面積:100μm×100μm
負荷曲線における負荷面積率:10%及び90%
銅箔エッチング後の転写表面の蒸留水接触角θ1を測定するために作製したものと同様の銅張積層板の表面処理銅箔上に、L&Sが50/50μmのレジストパターンを、サブトラクティブ工法により形成した。そして、表面処理銅箔のエッチングを行って、配線パターンを有する回路を形成した。レジストとしてはドライレジストフィルムを使用し、エッチング液としては塩化銅と塩酸を含有する混合液を使用した。
回路を形成した銅張積層板を切断して、樹脂製部材の表面に直交する断面を出し、走査型電子顕微鏡で回路の断面を観察した。そして、図2に示す断面上の角度Xと角度Yを測定した。角度Xは、回路31のトップ端部31aとボトム端部31bを結ぶ直線と樹脂製部材の表面とがなす角度である。角度Yは、回路31のボトム端部31bの接線と樹脂製部材の表面とがなす角度である。
銅箔エッチング後の転写表面の蒸留水接触角θ1を測定するために作製したものと同様の銅張積層板を用いて、ストリップ線路を形成したプリント配線板を作製し、伝送特性を評価した。このプリント配線板に形成されているストリップ線路の回路幅は140μm、回路長は76mmとした。
銅箔エッチング後の転写表面の蒸留水接触角θ1を測定するために作製したものと同様の銅張積層板を、塩化第二銅と塩酸の混合液をエッチング液として用いてエッチングし、表面処理銅箔を全て除去した。残った樹脂製部材を十分に水洗した後、樹脂製部材の表面処理銅箔が貼り合わされていた表面(転写表面)に、上記の銅張積層板の作製に用いたものと同種の樹脂製部材と表面処理銅箔とをこの順に重ねて張り合わせ、さらに上記と同様の手順でエッチングして表面処理銅箔を全て除去した。これにより、2つの樹脂製部材が貼り合わされてなる樹脂製試料を得た。
これに対して、比較例1~14の表面処理銅箔は、樹脂製基材の転写表面の濡れ性が低いため、回路加工性、伝送損失、及び異物の発生のうちいずれかの特性が不十分であった。
20・・・表面処理層
20a・・・表面処理層の表面
21・・・粗化処理層
22・・・防錆処理層
30・・・表面処理銅箔
31・・・回路
31a・・・トップ端部
31b・・・ボトム端部
40・・・樹脂製基材(樹脂製部材)
40a・・・転写表面
41・・・樹脂製基材
50・・・銅張積層板
60・・・プリント配線板
100・・・異物
Claims (5)
- 銅箔基体と、前記銅箔基体の少なくとも一方の面に形成された表面処理層と、を有する表面処理銅箔であって、
前記表面処理層が粗化処理層及び防錆処理層の一方又は両方からなり、
前記表面処理層の表面の光学式粗さをISO25178に規定の方法に準拠して測定した場合に、算術平均粗さSaが0.04μm以上0.30μm以下であり、
前記表面処理銅箔の前記表面処理層上に樹脂製部材を貼り合わせた後に、前記表面処理銅箔をエッチングにより除去し、残った前記樹脂製部材の前記表面処理銅箔が貼り合わされていた表面である転写表面について、蒸留水の接触角θ1をJIS R3257:1999に規定の静滴法に準拠して測定するとともに、前記表面処理銅箔に貼り合わせる前の前記樹脂製部材の前記表面処理銅箔が後に貼り合わされる表面である非転写表面について、蒸留水の接触角θ0を前記静滴法に準拠して測定した場合に、前記接触角θ0と前記接触角θ1との差θ0-θ1が5°以上35°以下である表面処理銅箔。 - 前記転写表面の光学式粗さをISO25178に規定の方法に準拠して測定した場合に、算術平均粗さSaが0.020μm以上0.070μm以下であり、コア部の空間の容積Vvcが0.030mL/m2以上0.110mL/m2以下である請求項1に記載の表面処理銅箔。
- 前記転写表面の光学式粗さをISO25178に規定の方法に準拠して測定した場合に、算術平均粗さSaが0.020μm以上0.051μm以下であり、コア部の空間の容積Vvcが0.030mL/m2以上0.071mL/m2以下である請求項1に記載の表面処理銅箔。
- 請求項1~3のいずれか一項に記載の表面処理銅箔と、前記表面処理銅箔の前記表面処理層上に貼り合わされた樹脂製基材と、を備える銅張積層板。
- 請求項4に記載の銅張積層板を備えるプリント配線板。
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| WO2025205609A1 (ja) * | 2024-03-28 | 2025-10-02 | 古河電気工業株式会社 | 電磁波シールド用銅箔及びその製造方法、並びに電磁波シールド |
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| JPWO2023190833A1 (ja) | 2023-10-05 |
| CN118891402A (zh) | 2024-11-01 |
| JP7527501B2 (ja) | 2024-08-02 |
| KR20240169639A (ko) | 2024-12-03 |
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