Patterned copper foil with carrier and preparation method thereof

Abstract

The invention relates to a patterned copper foil with a carrier and a preparation method thereof. The patterned copper foil is composed of a carrier copper foil, a stripping layer, a stripping layer protection layer and a patterned copper foil layer. According to the method, the flash etching process of the carrier-attached ultrathin copper foil does not need to be added, and when the stripping layer protection layer is removed in the pretreatment process, the required etching amount is small, and the corrosion to other wiring layers is small, so that the influence on the line width and the line distance of the other wiring layers is small when the stripping layer protection layer is removed.

Description

Technical Field

[0001] The invention belongs to the technical field of electrolytic copper foil, and in particular relates to a patterned copper foil with a carrier and a preparation method thereof. Background Art

[0002] In recent years, with the growing demand for portable electronic devices and smart wearable devices, portable devices are developing towards lightweight, thin and miniaturized. Therefore, the key printed circuit boards are also designed and processed towards high-density wiring and thinness. The package carrier is a high-end printed circuit board that serves as a bridge between the chip and other components. It requires the thickness of the insulation layer to be further reduced and the line density to be further increased to match the design on the demand side.

[0003] In order to meet the above needs, the industry currently uses the coreless build-up method to produce high-end printed circuit boards and package carriers (such as patents CN103430642B and CN108029202B). It is characterized by using an extremely thin copper foil with a carrier, and by simultaneously pressing the extremely thin copper foil with a carrier on both sides of the supporting core material, the carrier copper foil is stacked toward the insulating material side, and the extremely thin copper foil is pressed away from the insulating material side. Subsequently, the MSAP (Modified Semi-Additive Process) process is used to form the wiring copper layer 1 of the printed circuit board on the extremely thin copper foil; the prepreg and the extremely thin copper foil with a carrier are continued to be pressed, and the wiring copper layer 2 of the printed circuit board is formed on the surface using the MSAP process; and so on to form a multi-layer wiring layer of the circuit board. Finally, the extremely thin copper foil with a carrier is peeled off from the supporting core material, and the extremely thin copper layer (such as Figure 1 shown).

[0004] In the prior art, the structure of the carrier copper foil is a carrier layer, a peeling layer and an ultra-thin copper layer. When preparing a printed circuit board and a packaging carrier, a coreless lamination method is adopted. Subsequently, the wiring copper layer of the printed circuit board is formed step by step on the ultra-thin copper foil by using the MSAP process. Finally, the ultra-thin copper layer is removed by flash etching to form a wiring copper layer. The conventional ultra-thin copper foil has a thickness of 1.5μm, 2μm and 3μm. With this method, the circuit is more corroded and the circuit copper thickness is not easy to control. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a patterned copper foil with a carrier and a preparation method thereof. The copper foil does not need to add a flash etching process for an extremely thin copper foil with a carrier. When the stripping layer and the protective layer are removed in a pre-treatment process, the required etching amount is small and the bite to other wiring layers is small. Therefore, when the removal is performed, the line width and line spacing of other wiring layers are also less affected.

[0006] The invention provides a patterned copper foil with a carrier, which consists of a carrier copper foil, a peeling layer, a peeling layer protection layer and a patterned copper foil layer.

[0007] Preferably, the carrier copper foil has a thickness of 9-35 μm.

[0008] Preferably, the peeling layer protective layer is composed of metallic copper.

[0009] Preferably, the peeling layer protective layer has a thickness between 100-500 nm.

[0010] Preferably, the patterned copper foil layer has a thickness between 3 μm and 35 μm.

[0011] Preferably, each side surface of the lamination surface of the patterned copper foil layer is roughened, and the roughness Rz of each side surface of the patterned copper foil is less than 2.0 μm.

[0012] Preferably, the lamination surface of the patterned copper foil layer is subjected to rust-proof treatment. The rust-proof layer comprises metal components and silane, wherein the metal components are composed of one or more of Ni, Mo, Zn, Cr, Co and W.

[0013] The present invention also provides a method for preparing a patterned copper foil with a carrier, comprising the following steps:

[0014] (1) electroplating a carrier copper foil on the surface of a cathode titanium roller by a raw foil electrolysis method, and peeling the copper foil from the surface of the cathode titanium roller to obtain a carrier copper foil;

[0015] (2) preparing a peeling layer on the surface of the carrier copper foil;

[0016] (3) forming a peeling layer protective layer on the surface of the peeling layer;

[0017] (4) cleaning the peeling layer protective layer by acid washing, coating or laminating a photosensitive material on the surface of the peeling layer protective layer, patterning the surface by ultraviolet light, and removing the uncured photosensitive material by alkaline aqueous solution;

[0018] (5) electroplating a patterned copper foil layer on the surface of the peeling layer protective layer by electrochemical deposition;

[0019] (6) The surface of the patterned copper foil layer is roughened and an anti-rust layer is prepared on the surface to obtain a patterned copper foil with a carrier.

[0020] Preferably, the method of preparing the peeling layer in step (2) includes one or more of electrochemical deposition, chemical deposition, immersion, coating, and spraying. The peeling layer may be composed of organic matter, inorganic matter, or a combination of organic matter and inorganic matter.

[0021] Preferably, the method of preparing the peeling layer protective layer in step (3) comprises electrochemical deposition or physical vapor deposition.

[0022] The carrier copper foil in the present invention plays the role of the base in the copper foil production process, and also plays the role of the support in the lamination process, and is directly prepared by electrolysis of raw foil. The peeling layer plays the role of peeling after high-temperature lamination, and is prepared on the surface of the carrier copper foil by electrochemical deposition, chemical deposition, immersion, coating, spraying, etc. The peeling layer protective layer plays the role of protecting the peeling layer from being corroded by the medicine in the subsequent copper foil processing process, and can be peeled after lamination in the printed circuit board factory. The patterned copper foil layer can quickly form a wiring copper layer in the printed circuit board factory through lamination and pre-treatment processes. The advantage is that the copper thickness is better controllable, the product has higher bonding strength and better reliability.

[0023] Beneficial Effects

[0024] (1) The present invention prepares a patterned copper foil layer, roughens its surface, and embeds it into a prepreg by lamination. After lamination, the carrier copper foil is peeled off to directly form a wiring copper layer of a printed circuit board (such as Figure 2 and Figure 3 As shown). After the wiring copper layer is embedded in the prepreg, since all three surfaces of the circuit are roughened, the bonding force between the copper foil and the prepreg is good and the reliability is high. The wiring copper layer is embedded in the prepreg by pressing, and the circuit will not be wet etched again. The verticality of the circuit is high, the circuit etching factor is good, and the line width and line spacing are in good compliance with the design value; at the same time, the difficulty of etching the base copper is reduced, and the copper thickness can be controlled more finely.

[0025] (2) The thickness of the peeling layer protective layer of the present invention is less than 500nm. Although it is slightly thickened after the patterned copper foil layer roughening process, it can still be directly removed by the process of pattern pre-treatment micro-etching / pressing pre-treatment / solder mask pre-treatment, etc., without adding the flash etching process of the ultra-thin copper foil attached to the carrier. The peeling layer protective layer is very thin, and when it is removed in the pre-treatment process, the required etching amount is small, and the bite corrosion to other wiring layers is small, so when it is removed, the influence on the line width and line spacing of other wiring layers is also small. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a diagram showing the method of using copper foil in the prior art.

[0027] Figure 2 This is a diagram illustrating a first method of using the copper foil of the present invention.

[0028] Figure 3 This is a diagram illustrating a second method of using the copper foil of the present invention.

[0029] Figure 4 The present invention is a flow chart of the preparation of the copper foil. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0031] Example 1

[0032] This embodiment provides a method for preparing a patterned copper foil with a carrier, such as Figure 4 The specific solution process is as follows:

[0033] (1) Step A Preparation of carrier copper foil: a raw foil with a thickness of 18 μm is produced by electrolysis. The process parameters are as follows:

[0034] Copper concentration: 90-100g / L;

[0035] Sulfuric acid concentration: 110-120g / L;

[0036] Chloride ion concentration: <30mg / L;

[0037] Additive (collagen or gelatin) concentration: <20 mg / L;

[0038] Temperature: 50℃;

[0039] Current density: 70A / dm 2 .

[0040] (2) Step B: Pickling pretreatment: the carrier copper foil to be treated is passed through a pickling tank to remove the oxide layer on the surface. The process parameters are as follows:

[0041] Copper concentration: <8g / L;

[0042] Sulfuric acid concentration: 140±5g / L;

[0043] Temperature: 28℃;

[0044] Preprocessing time: 8S.

[0045] (3) Preparation of the peeling layer in step C: forming a metal alloy layer by electrochemically depositing metal nickel and cobalt; and then immersing the layer in a carboxybenzotriazole aqueous solution to form an inorganic / organic composite peeling layer.

[0046] (4) Step D: Preparation of the peeling layer protective layer: The peeling layer protective layer is generated by electrolysis. The component is metallic copper. The thickness of the protective layer copper is 300 nm. The process parameters are as follows:

[0047] Copper concentration: 50g / L;

[0048] Sulfuric acid concentration: 120g / L;

[0049] Temperature: 50℃;

[0050] Electroplating time: 5S;

[0051] Current density: 70A / dm 2 .

[0052] (5) Step E: Drying: Use hot air to dry the copper foil.

[0053] (6) Step F: Anti-plating and anti-corrosion layer bonding, using anti-plating dry film, bonded to the surface of the peeling layer and protective layer.

[0054] (7) Step G exposure: using ultraviolet light to cure the anti-plating and anti-corrosion dry film at a specific position, designing the exposure pattern according to the requirements, patterning the copper foil surface, and the dry film cured portion is the unnecessary portion of the patterned copper foil layer.

[0055] (8) Step H: Development: Use a weak alkali aqueous solution, such as a 1 wt% sodium carbonate aqueous solution, to develop and remove the uncured anti-plating and anti-corrosion dry film. The portion not covered by the anti-plating and anti-corrosion layer is the patterned copper layer portion.

[0056] (9) Step I: Patterned copper layer is prepared by electroplating. The thickness of the copper layer deposited by electroplating is 9 μm. The electroplating process parameters are as follows:

[0057] Copper concentration: 90-100g / L;

[0058] Sulfuric acid concentration: 110-120g / L;

[0059] Chloride ion concentration: <30mg / L;

[0060] Additive (collagen or gelatin) concentration: <20 mg / L;

[0061] Temperature: 50℃;

[0062] Current density: 70A / dm 2 .

[0063] (10) Step J: film stripping: removing the anti-plating and anti-corrosion dry film by film stripping. Using a strong alkaline solution, such as a 3 wt % sodium hydroxide aqueous solution at a temperature of 60° C., the solidified anti-plating and anti-corrosion dry film is cleaned and removed.

[0064] (11) Step K: Roughening treatment: After the roughening treatment tank, the copper nodules on the surface of the patterned copper foil layer are promoted to grow and the roughness is increased. The process parameters are as follows:

[0065] Copper concentration: 12 g / L;

[0066] Sulfuric acid concentration: 140g / L;

[0067] Temperature: 28℃;

[0068] Plating time: 7S;

[0069] Current density: 60A / dm 2 .

[0070] (7) Step L curing electroplating: curing the copper nodules grown by the roughening treatment in step K, so that the roughened copper nodules are more firmly bonded to the patterned copper foil layer substrate, and the process parameters are as follows:

[0071] Copper concentration: 50g / L;

[0072] Sulfuric acid concentration: 120g / L;

[0073] Temperature: 50℃;

[0074] Plating time: 7S;

[0075] Current density: 70A / dm 2 .

[0076] (8) Step M: Repeat steps F and G once or twice according to the roughness requirement to increase the number and size of copper nodules after treatment, and the final roughness Rz is 1.5 μm.

[0077] (9) Step N Blackening Treatment: A layer of Ni is deposited on the surface of the patterned copper layer after rough curing to provide the copper foil with better chemical corrosion resistance. The process parameters are as follows:

[0078] K 4 P 2 O 7 =85g / L;

[0079] NiSO 4 .6H 2 O = 4.5 g / L;

[0080] Current density: 10A / dm 2 ;

[0081] Blackening liquid temperature: 40℃;

[0082] Blackening liquid pH = 8.5;

[0083] Electroplating time: 7S.

[0084] (10) Step O Ashing Treatment: After the N-stage blackening treatment, the surface of the patterned copper layer is subjected to electroplating with a potassium pyrophosphate and zinc sulfate complex solution system to deposit metal Zn, thereby providing the copper foil with better anti-oxidation performance. The process parameters are as follows:

[0085] K 4 P 2 O 7 =85g / L;

[0086] ZnSO 4 .6H 2 O = 5.5 g / L;

[0087] Current density: 10A / dm 2 ;

[0088] Ashing liquid temperature: 40℃;

[0089] Ashing liquid pH = 8.5;

[0090] Electroplating time: 7S.

[0091] (11) Step P: Passivation treatment: When the surface of the patterned copper layer passes through the chromic anhydride solution system, a layer of Cr is electroplated on the surface of the copper foil to provide room temperature anti-oxidation performance. The process parameters are as follows:

[0092] Cr 6+ (chromic anhydride) = 1.5 g / L;

[0093] Current density: 15A / dm 2 ;

[0094] Passivation solution temperature: 35°C;

[0095] Passivation solution pH = 11;

[0096] Electroplating time: 7S.

[0097] (12) Step Q, silane coating: A layer of silane coupling agent is coated on the surface of the patterned copper layer by immersion to enhance the chemical bonding between the copper foil and the substrate. The process parameters are as follows:

[0098] The types of silanes are: epoxy silanes;

[0099] Si content>1200ppm;

[0100] The silane solution is clear and transparent.

[0101] (13) Step M, drying: drying the residual moisture on the foil surface and promoting the coupling reaction between the silane coupling agent and the hydroxyl groups on the surface of the copper foil.

[0102] Example 2

[0103] This embodiment provides a method for preparing a patterned copper foil with a carrier, and the specific process is as follows:

[0104] (1) Step A Preparation of carrier copper foil: a raw foil with a thickness of 35 μm is produced by electrolysis. The process parameters are as follows:

[0105] Copper concentration: 90-100g / L;

[0106] Sulfuric acid concentration: 110-120g / L;

[0107] Chloride ion concentration: <30mg / L;

[0108] Additive (collagen or gelatin) concentration: <20 mg / L;

[0109] Temperature: 50℃;

[0110] Current density: 70A / dm 2 .

[0111] (2) Step B: Pickling pretreatment: the carrier copper foil to be treated is passed through a pickling tank to remove the oxide layer on the surface. The process parameters are as follows:

[0112] Copper concentration: <8g / L;

[0113] Sulfuric acid concentration: 140±5g / L;

[0114] Temperature: 28℃;

[0115] Preprocessing time: 8S.

[0116] (3) Preparation of the stripping layer in step C: forming an alloy layer by electrochemically depositing metal molybdenum and nickel; at the same time, the electrolyte contains nitrogen-containing organic compounds, the compounds are benzotriazole and carboxybenzotriazole; forming an organic / inorganic composite stripping layer.

[0117] (4) Step D: Preparation of the peeling layer protective layer: The peeling layer protective layer is formed by electrolysis, and the component is metallic copper. The thickness of the protective layer copper is 400nm, and the process parameters are as follows:

[0118] Copper concentration: 50g / L;

[0119] Sulfuric acid concentration: 120g / L;

[0120] Temperature: 50℃;

[0121] Plating time: 6S;

[0122] Current density: 70A / dm 2 .

[0123] (5) Step E: Drying: Use hot air to dry the copper foil.

[0124] (6) Step F: Anti-plating and anti-corrosion layer lamination, using anti-plating dry film, laminating on the surface of the peeling layer and protective layer.

[0125] (7) Step G exposure: using ultraviolet light to cure the anti-plating and anti-corrosion dry film at a specific position, designing the exposure pattern according to the requirements, patterning the copper foil surface, and the dry film cured portion is the unnecessary portion of the patterned copper foil layer.

[0126] (8) Step H: Development: Use a weak alkali aqueous solution, such as a 1 wt% sodium carbonate aqueous solution, to develop and remove the uncured anti-plating and anti-corrosion dry film. The portion not covered by the anti-plating and anti-corrosion layer is the patterned copper layer portion.

[0127] (9) Step I: Patterned copper layer is prepared by electroplating. The thickness of the copper layer deposited by electroplating is 12 μm. The electroplating process parameters are as follows:

[0128] Copper concentration: 90-100g / L;

[0129] Sulfuric acid concentration: 110-120g / L;

[0130] Chloride ion concentration: <30mg / L;

[0131] Additive (collagen or gelatin) concentration: <20 mg / L;

[0132] Temperature: 50℃;

[0133] Current density: 70A / dm 2 .

[0134] (10) Step J: film stripping: the dry film of the anti-plating and anti-corrosion is removed by film stripping. A strong alkaline solution, such as a 3 wt % sodium hydroxide aqueous solution at a temperature of 60° C., is used to clean and remove the solidified dry film of the anti-plating and anti-corrosion.

[0135] (11) Step K: Roughening treatment: After the roughening treatment tank, the copper nodules on the surface of the patterned copper foil layer are promoted to grow and the roughness is increased. The process parameters are as follows:

[0136] Copper concentration: 12 g / L;

[0137] Sulfuric acid concentration: 140g / L;

[0138] Temperature: 28℃;

[0139] Plating time: 7S;

[0140] Current density: 60A / dm 2 .

[0141] (7) Step L curing electroplating: curing the copper nodules grown by the roughening treatment in step K, so that the roughened copper nodules are more firmly bonded to the patterned copper foil layer substrate, and the process parameters are as follows:

[0142] Copper concentration: 50g / L;

[0143] Sulfuric acid concentration: 120g / L;

[0144] Temperature: 50℃;

[0145] Plating time: 7S;

[0146] Current density: 70A / dm 2 .

[0147] (8) Step M: Repeat steps F and G once or twice according to the roughness requirement to increase the number and size of copper nodules after treatment. The final roughness Rz is 1.8 μm.

[0148] (9) Step N Blackening Treatment: A layer of Ni is deposited on the surface of the patterned copper layer after rough curing to provide the copper foil with better chemical corrosion resistance. The process parameters are as follows:

[0149] K 4 P 2 O 7 =85g / L;

[0150] NiSO 4 .6H 2 O = 4.5 g / L;

[0151] Current density: 10A / dm 2 ;

[0152] Blackening liquid temperature: 40℃;

[0153] Blackening liquid pH = 8.5;

[0154] Electroplating time: 7S.

[0155] (10) Step O Ashing Treatment: After the N-stage blackening treatment, the surface of the patterned copper layer is subjected to electroplating with a potassium pyrophosphate and zinc sulfate complex solution system to deposit metal Zn, thereby providing the copper foil with better anti-oxidation performance. The process parameters are as follows:

[0156] K 4 P 2 O 7 =85g / L;

[0157] ZnSO 4 .6H 2 O = 5.5 g / L;

[0158] Current density: 10A / dm 2 ;

[0159] Ashing liquid temperature: 40℃;

[0160] Ashing liquid pH = 8.5;

[0161] Electroplating time: 7S.

[0162] (11) Step P: Passivation treatment: When the surface of the patterned copper layer passes through the chromic anhydride solution system, a layer of Cr is electroplated on the surface of the copper foil to provide room temperature anti-oxidation performance. The process parameters are as follows:

[0163] Cr 6+ (chromic anhydride) = 1.5 g / L;

[0164] Current density: 15A / dm 2 ;

[0165] Passivation solution temperature: 35°C;

[0166] Passivation solution pH = 11;

[0167] Electroplating time: 7S.

[0168] (12) Step Q, silane coating: A layer of silane coupling agent is coated on the surface of the patterned copper layer by immersion to enhance the chemical bonding between the copper foil and the substrate. The process parameters are as follows:

[0169] The types of silanes are: epoxy silanes;

[0170] Si content>1200ppm;

[0171] The silane solution is clear and transparent.

[0172] (13) Step M, drying: drying the residual moisture on the foil surface and promoting the coupling reaction between the silane coupling agent and the hydroxyl groups on the surface of the copper foil.

Claims

1. A patterned copper foil with a carrier, characterized in that: It consists of a carrier copper foil, a peeling layer, a peeling layer protection layer and a patterned copper foil layer.

2. The patterned copper foil according to claim 1, characterized in that: The carrier copper foil has a thickness of 9-35 μm.

3. The patterned copper foil according to claim 1, characterized in that: The peeling layer protective layer is composed of metallic copper.

4. The patterned copper foil according to claim 1, characterized in that: The thickness of the peeling layer protection layer is between 100-500nm.

5. The patterned copper foil according to claim 1, wherein: The thickness of the patterned copper foil layer is between 3 μm and 35 μm.

6. The patterned copper foil according to claim 1, characterized in that: Each side surface of the patterned copper foil laminate is roughened.

7. The patterned copper foil according to claim 1, characterized in that: The laminated surface of the patterned copper foil layer is subjected to rust-proof treatment.

8. A method for preparing a patterned copper foil with a carrier, comprising the following steps: (1) electroplating a carrier copper foil on the surface of a cathode titanium roller by a raw foil electrolysis method, and peeling the copper foil from the surface of the cathode titanium roller to obtain a carrier copper foil; (2) preparing a peeling layer on the surface of the carrier copper foil; (3) forming a peeling layer protective layer on the surface of the peeling layer; (4) cleaning the peeling layer protective layer by acid washing, coating or laminating a photosensitive material on the surface of the peeling layer protective layer, patterning the surface by ultraviolet light, and removing the uncured photosensitive material by alkaline aqueous solution; (5) electroplating a patterned copper foil layer on the surface of the peeling layer protective layer by electrochemical deposition; (6) The surface of the patterned copper foil layer is roughened and an anti-rust layer is prepared on the surface to obtain a patterned copper foil with a carrier.

9. The preparation method according to claim 8, characterized in that: The method of preparing the peeling layer in step (2) includes one or more of electrochemical deposition, chemical deposition, immersion, coating, and spraying.

10. The preparation method according to claim 8, characterized in that: The method of preparing the peeling layer protective layer in step (3) includes electrochemical deposition or physical vapor deposition.

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