A surface treatment process for copper foil, its products and applications

Abstract

The present invention discloses a surface treatment process for copper foil, which includes pickling, rough curing treatment, anti-oxidation treatment and silanization treatment on the raw foil in sequence. The silanization treatment specifically includes: mixing a silane coupling agent, a surfactant and a crosslinking agent with water, coating the mixture on the treated surface of the copper foil after sufficient hydrolysis, and drying to obtain the copper foil; the silane coupling agent is selected from vinylbenzyl silane coupling agents; the surfactant is selected from non-ionic surfactants; the crosslinking agent is selected from amine crosslinking agents. The surface treatment process for copper foil disclosed by the present invention can significantly improve the peel strength between the copper foil and the resin substrate, and can also significantly improve the heat resistance and aging resistance of the copper clad laminate composed of the copper foil and the resin substrate.

Description

Technical Field

[0001] The present invention belongs to the technical field of copper foils, and particularly relates to a surface treatment process of copper foils, its products and applications. Background Art

[0002] Copper foils are increasingly widely used in high-end industries such as 5G communication and new energy vehicles, and the requirements for their performance are also increasing day by day. As an important part of PCB copper clad laminates (CCLs), copper foils play a crucial role in the signal and power transmission of electronic products. In order to optimize the performance of copper foils, it is necessary to reduce the "skin effect" on their surfaces, reduce the size of copper nodules, and at the same time reduce the mechanical bonding force between them and the prepreg.

[0003] Silane coupling agents are a class of organosilicon compounds that contain two different chemically active groups in their molecular structures and can react with the substrate and copper foil respectively, thus building a "molecular bridge" between them. For modified PPO substrates, using vinylbenzyl silane coupling agents can greatly improve the peel strength between copper foils and modified PPO substrates. However, because the silane has a long-chain molecule and the organic end is prone to self-polymerization, oligomers are likely to be produced within a few hours after formulation. These oligomers are sprayed onto the copper foil surface with the hydrolysis solution and then sintered in an oven, forming black spots on the copper foil surface, which affect the appearance and quality of the copper foil. At the same time, due to the presence of contours on the copper foil surface, the silane cannot effectively form a monolayer, and the coupling effect of the silane coupling agent cannot be effectively exerted. Summary of the Invention

[0004] In view of the above problems, the present invention discloses a surface treatment process of copper foils, which can significantly improve the peel strength between copper foils and resin substrates, and can also significantly improve the heat resistance and aging resistance of copper clad laminates composed of copper foils and resin substrates.

[0005] To achieve the above object, the specific technical solution of the present invention is as follows:

[0006] A surface treatment process of copper foils includes pickling, rough curing treatment, anti-oxidation treatment and silanization treatment on the raw foil in sequence. The silanization treatment specifically includes:

[0007] Mixing a silane coupling agent, a surfactant and a crosslinking agent with water, coating the mixture on the treated surface of the copper foil after sufficient hydrolysis, and drying to obtain the copper foil;

[0008] The silane coupling agent is selected from vinylbenzyl silane coupling agents;

[0009] The surfactant is selected from non-ionic surfactants;

[0010] The crosslinking agent is selected from amine crosslinking agents.

[0011] In the present invention, a surfactant and a crosslinking agent are mixed with a silane coupling agent and hydrolyzed before being coated on the surface of a treated copper foil. Tests have found that after this surface treatment, the peel strength between the copper foil and resin substrates, including modified PPO resin, PTFE resin, and epoxy resin, can be significantly improved, and the heat resistance and aging resistance of the copper clad laminate composed of the copper foil and resin substrates can also be significantly enhanced. This may be because the combination of the three can result in a crosslinked monomolecular network structure of vinylbenzyl silane coupling agent on the surface of the copper foil, obtaining a stable bonding force after lamination with the resin substrate.

[0012] Tests have found that if the silane coupling agent is mixed with a single surfactant or a single crosslinking agent; or if the type of crosslinking agent used is inappropriate, neither can the black spot problem caused by the self-polymerization of vinylbenzyl silane coupling agent be improved, nor can the peel strength between the copper foil and resin substrate be significantly enhanced, nor can its heat resistance and aging resistance be improved.

[0013] Preferably:

[0014] The vinylbenzyl silane coupling agent is selected from one or more of KH-6032, 9669, and SKT1-5132.

[0015] The non-ionic surfactant is selected from ZY-1604 alkynol polyether surfactants and / or LAE-9 polyoxyethylene fatty acid ester surfactants.

[0016] The amine crosslinking agent is selected from one or more of diaminodiphenylmethane, diaminodiphenylsulfone, m-xylenediamine, m-aminobenzylamine, and 2,6-diaminopyridine.

[0017] Preferably:

[0018] The mass ratio of the surfactant to the silane coupling agent is 1:(10 - 50); specifically, it can be 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50 or any ratio within the range; more preferably 1:(20 - 40).

[0019] The mass ratio of the crosslinking agent to the silane coupling agent is 1:(10 - 50); specifically, it can be 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50 or any ratio within the range; more preferably 1:(20 - 40).

[0020] The mass ratio of the silane coupling agent to water is (0.5 - 5.0):100; specifically, it can be 0.5:100, 1.0:100, 1.5:100, 2.0:100, 2.5:100, 3.0:100, 3.5:100, 4.0:100, 4.5:100, 5.0:100 or any ratio within the range; more preferably (0.5 - 2.0):100.

[0021] In the present invention:

[0022] The hair foil has a thickness of 18 - 35 μm and a surface roughness Rz ≤ 0.7 μm on the smooth side;

[0023] The pickling treatment uses a copper sulfate pickling solution, and the treatment temperature is 10 - 50 °C;

[0024] The rough curing treatment includes roughening treatment and curing treatment on the smooth side of the hair foil, and the Rz after treatment ≤ 1.3 μm;

[0025] For the roughening treatment, the copper ion concentration in the plating solution is 5 - 30 g / L, the sulfuric acid concentration is 50 - 200 g / L, the plating solution temperature is 10 - 40 °C, and the roughening current density is 10 - 50 A / dm 2 ;

[0026] For the curing treatment, the copper ion concentration in the plating solution is 30 - 100 g / L, the sulfuric acid concentration is 40 - 180 g / L, the plating solution temperature is 30 - 60 °C, and the curing current density is 10 - 50 A / dm 2 。

[0027] The anti - oxidation treatment is specifically electroplating a metal layer on the hair foil after the rough curing treatment.

[0028] Preferably:

[0029] The electroplated metal layer includes an electroplated nickel layer and an electroplated zinc layer;

[0030] When electroplating the nickel layer, the nickel ion concentration in the plating solution is 10 - 25 g / L, the potassium pyrophosphate concentration is 30 - 70 g / L, and the current density is 0.4 - 2.0 A / dm 2 ; specifically, it can be 0.40, 0.45, 0.50, 0.55, 0.60, 0.70, 0.80, 0.90, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 A / dm 2 or any value within the range.

[0031] When electroplating the zinc layer, the zinc ion concentration in the plating solution is 20 - 40 g / L, the potassium pyrophosphate concentration is 30 - 70 g / L, and the current density is 0.5 - 2.5 A / dm2 ; Specifically, it can be 0.50, 0.55, 0.60, 0.62, 0.65, 0.70, 0.80, 0.90, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5 A / dm 2 Or any value within the range.

[0032] It has been found through experiments that the process parameters in the anti-oxidation treatment step before the silanization treatment step, especially the control of the current density, also have a crucial impact on the heat resistance and aging resistance of the finally prepared copper foil.

[0033] Further preferably:

[0034] When electroplating the metal nickel layer, the current density is 0.8 - 1.2 A / dm 2 ;

[0035] When electroplating the metal zinc layer, the current density is 1.0 - 1.5 A / dm 2 .

[0036] It has been found through experiments that by using the above further optimized process parameters and combining with the subsequent silanization treatment, the heat resistance and aging resistance of the finally prepared copper clad laminate composed of copper foil and resin substrate are better.

[0037] The present invention also discloses a copper foil prepared according to the above surface treatment process, and the application of the copper foil in the preparation of PCB copper clad laminates.

[0038] The raw materials for preparing PCB copper clad laminates include copper foil and resin substrate. It has been found through experiments that when the resin substrate is selected from polyphenylene ether, polytetrafluoroethylene or epoxy resin, the copper foil prepared by using the surface treatment process disclosed in the present invention can significantly improve the peel strength between the copper foil and the resin substrate, as well as the heat resistance and aging resistance of the copper clad laminate.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention discloses a surface treatment process for copper foil. By mixing a surfactant and a crosslinking agent with a silane coupling agent and coating it on the surface of the treated copper foil after hydrolysis, the peel strength between the copper foil and resin substrates, including modified PPO resin, PTFE resin, and epoxy resin, can be significantly improved, and the heat resistance and aging resistance of the copper clad laminate composed of copper foil and resin substrate can also be significantly improved. It plays a good promoting role in the application of copper foil in the field of PCB copper clad laminates. Description of the Drawings

[0041] Figure 1Photos of the hydrolyzates prepared for Examples 1 to 5 respectively, with that of Comparative Example 1 given for comparison;

[0042] Figure 2 Surface photos of the copper foils prepared for Comparative Example 1 and Examples 1 to 5 respectively;

[0043] Figure 3 Surface photos of the copper foils prepared for Example 1 and Comparative Examples 1 to 5 respectively. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0045] In the description of the present invention, it should be noted that for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. The embodiments of the present invention will be described below according to the overall structure of the present invention. Unless otherwise specified, the raw materials in the embodiments of the present application are all purchased through commercial channels.

[0046] Example 1

[0047] (1) Pickling treatment

[0048] Pickling is carried out on the hair foil with a thickness of 18 μm:

[0049] The copper ion concentration in the pickling solution is 13 g / L, the sulfuric acid concentration is 160 g / L, and the temperature of the pickling solution is 30 °C.

[0050] (2) Coarse curing treatment

[0051] The pickled hair foil is subjected to coarse curing treatment, and the treatment process is roughening → curing:

[0052] The copper ion concentration in the plating solution used for roughening treatment is 13 g / L, the sulfuric acid concentration is 160 g / L, the temperature of the plating solution is 30 °C, and the current density of the roughening treatment is 32 A / dm 2 ;

[0053] The copper ion concentration in the plating solution used for curing treatment is 40 g / L, the sulfuric acid concentration is 90 g / L, the temperature of the plating solution is 56 °C, and the current density of the curing treatment is 40 A / dm 2 .

[0054] (3) Anti-oxidation treatment

[0055] The anti-oxidation treatment sequentially includes electroplating a nickel metal layer and a zinc metal layer;

[0056] For the electroplated nickel metal layer, the nickel ion concentration in the plating solution is 15 g / L, the potassium pyrophosphate concentration is 30 g / L, the plating solution temperature is 30 °C, and the current density is 1 A / dm 2 ;

[0057] For the electroplated zinc metal layer, the Zn ion concentration in the plating solution is 29 g / L, the potassium pyrophosphate concentration is 58 g / L, the plating solution temperature is 33 °C, and the current density is 1.2 A / dm 2 .

[0058] (4) Silanization treatment

[0059] Mix KH-6032, ZY-1604 alkynol polyether surfactant and diaminodiphenylmethane (DDM) with water. The mass ratio of KH-6032, ZY-1604 alkynol polyether surfactant to DDM is 20:1:1, and the mass ratio of KH-6032 to water is 1.2:100; after sufficient hydrolysis, let it stand for 1 day, then filter the obtained hydrolysis solution by suction, coat the filtrate on the treated surface of the copper foil, and dry it at 100 °C to obtain a modified copper foil; weigh the insoluble matter obtained by suction filtration and record the weight in Table 1 below.

[0060] Table 1

[0061]

[0062] Example 2

[0063] The preparation process is basically the same as that in Example 1, except that in step (4):

[0064] Replace the cross-linking agent with diaminodiphenyl sulfone (DDS), and the mass ratio of KH-6032, ZY-1604 alkynol polyether surfactant to DDS is 30:1:1.5.

[0065] Record the weight of the insoluble matter in Table 1.

[0066] Example 3

[0067] The preparation process is basically the same as that in Example 1, except that in step (4):

[0068] Replace the cross-linking agent with m-xylenediamine (MXDA), and the mass ratio of KH-6032, ZY-1604 alkynol polyether surfactant to MXDA is 40:2:1.

[0069] Record the weight of the insoluble matter in Table 1.

[0070] Example 4

[0071] The preparation process is basically the same as that in Example 1, except that in step (4):

[0072] The silane coupling agent is replaced by 9669, the cross-linking agent is replaced by m-aminobenzylamine (MABA), and the mass ratio of 9669, ZY-1604 alkynol polyether surfactant to MABA is 20:1:1.

[0073] The weight of the insoluble matter is recorded in Table 1.

[0074] Example 5

[0075] The preparation process is basically the same as that in Example 1, except that in step (4):

[0076] The surfactant is replaced by LAE-9 polyoxyethylene fatty acid ester surfactant, the cross-linking agent is replaced by 2,6-diaminopyridine (DAPY), and the mass ratio of KH-6032, LAE-9 polyoxyethylene fatty acid ester surfactant to DAPY is 20:1:1.

[0077] The weight of the insoluble matter is recorded in Table 1.

[0078] Example 6

[0079] The preparation process is basically the same as that in Example 1, except that in step (1):

[0080] A rough curing treatment is carried out using a wool foil with a thickness of 35 μm.

[0081] Example 7

[0082] The preparation process is basically the same as that in Example 1, except that in step (3):

[0083] When electroplating the nickel metal layer, the current density is replaced by 0.45 A / dm 2 ;

[0084] When electroplating the zinc metal layer, the current density is replaced by 0.62 A / dm 2 .

[0085] Example 8

[0086] The preparation process is basically the same as that in Example 1, except that in step (3):

[0087] When electroplating the nickel metal layer, the current density is replaced by 1.4 A / dm 2 ;

[0088] When electroplating the zinc metal layer, the current density is replaced by 2.5 A / dm 2 .

[0089] Comparative Example 1

[0090] The preparation process is basically the same as that in Example 1, except that in step (4):

[0091] Only a single KH-6032 is added, and the mass ratio of KH-6032 to water is 1.2:100.

[0092] The weight of the insoluble matter is recorded in Table 1.

[0093] Comparative Example 2

[0094] The preparation process is basically the same as that in Example 1, except that in step (4):

[0095] Only KH-6032 and ZY-1604 alkynol polyether surfactant are added, and the mass ratio of KH-6032 to ZY-1604 alkynol polyether surfactant is 20:1, and the mass ratio of KH-6032 to water is 1.2:100.

[0096] Comparative Example 3

[0097] The preparation process is basically the same as that in Example 1, except that in step (4):

[0098] Only KH-6032 and DDM are added, and the mass ratio of KH-6032 to DDM is 20:1, and the mass ratio of KH-6032 to water is 1.2:100.

[0099] Comparative Example 4

[0100] The preparation process is basically the same as that in Example 1, and the only difference is that in step (4):

[0101] DDM is replaced with an equal mass of benzoyl peroxide crosslinking agent (BPO).

[0102] Comparative Example 5

[0103] The preparation process is basically the same as that in Example 1, and the only difference is that in step (4):

[0104] DDM is replaced with an equal mass of tetramethylthiuram disulfide crosslinking agent (TMTD).

[0105] Comparative Example 6

[0106] The preparation process is basically the same as that in Example 1, and the only difference is that in step (4):

[0107] DDM is replaced with an equal mass of vinyltrimethoxysilane crosslinking agent (LA-171).

[0108] Figure 1The appearance photos of the hydrolysis solutions prepared in Examples 1-5 and Comparative Example 1 were compared. It was found that, among Examples 1-5, the hydrolysis solutions were significantly clearer, with no obvious turbidity or precipitation observed, and the precipitation mass was significantly lower than that of Comparative Example 1. This conclusion is consistent with the data in Table 1.

[0109] Figure 2 The surface photos of the copper foils prepared in Examples 1-5 and Comparative Example 1 were shown. It was observed that obvious black dots existed on the surface of the copper foil prepared in Comparative Example 1, while no black dots appeared on the surfaces of the copper foils prepared in Examples 1-5. This indicates that the addition of surfactants and amine crosslinking agents significantly improved the problem of black dots caused by vinylbenzyl silane coupling agents on the copper foil surface.

[0110] Figure 3 The surface photos of the copper foils prepared in Example 1 and Comparative Examples 1-5 were shown. It was observed that no black dots appeared on the surface of the copper foil prepared in Example 1, while obvious black dots existed on the surfaces of the copper foils prepared in Comparative Examples 1-5. This indicates that when using a single surfactant or a single amine crosslinking agent mixed with vinylbenzyl silane coupling agent, the problem of black dots cannot be improved, and when using inappropriate crosslinking agents, such as organic peroxide-based, organic sulfur-based or silane-based crosslinking agents, the problem of black dots cannot be improved either.

[0111] Application test:

[0112] 1. The modified copper foils and modified PPO substrates (Shengyi Technology, S6) prepared in each example and comparative example were subjected to high-temperature lamination at a temperature of 220 °C and a pressure of 19.3 Mpa to form copper-clad laminates. The laminated samples were etched into 3-mm-wide stripping strip long strips, and a stripping experiment was carried out using a 90-degree universal stripping strength tester (testing standard IPC-TM-650-2.4.8). The specific data of the normal-state anti-stripping strength are listed in Table 2 below. To further investigate its aging resistance, the prepared copper-clad laminates were taken out after being baked in an oven at 180 °C for 72 h, and their anti-stripping strength was tested to determine their aging resistance; to further investigate its heat resistance, the copper-clad laminates were taken out after being placed in a 288 °C tin furnace for 20 min, and their anti-stripping strength was tested to determine their heat resistance (testing standard IPC-TM-650-2.4.14). The specific values are listed in Table 2 below.

[0113] Table 2

[0114]

[0115] It can be seen from the data in Comparative Table 2 that by using a surfactant, a crosslinking agent and a silane coupling agent in combination for surface treatment of the copper foil, the peel strength of the copper foil with various resin substrates can be significantly improved, and the heat resistance and aging resistance of the copper clad laminate can be enhanced. If the silane coupling agent is used alone (Comparative Example 1), or the silane coupling agent is mixed with a surfactant alone (Comparative Example 2) or a crosslinking agent alone (Comparative Example 3); or the type of crosslinking agent used is inappropriate (Comparative Examples 4-6), the technical effects in the examples cannot be obtained.

[0116] Comparing Examples 1, 6 and 7, it can be seen that the control of process parameters in the previous anti-oxidation treatment also affects the technical effects of the silanization treatment, and thus affects the heat resistance and aging resistance of the copper clad laminate finally prepared from the copper foil and the resin substrate.

[0117] 2. The modified copper foils prepared in Comparative Example 1 and Example 3 were subjected to high-temperature lamination with an epoxy resin substrate (Shengyi Technology, S1000-2MB) at a temperature of 200 °C and a pressure of 19.3 Mpa to make copper clad laminates. The tests of the normal-state peel strength, the peel strength after aging and after tin immersion were the same as those in 1, and the specific data are listed in Table 3 below. The modified copper foils prepared in Comparative Example 1 and Example 3 were subjected to high-temperature lamination with a PTFE substrate (Huazheng New Materials, H5220) at a temperature of 310 °C and a pressure of 65 Mpa to make copper clad laminates. The tests of the normal-state peel strength, the peel strength after aging and after tin immersion were the same as those in 1, and the specific data are also listed in Table 3 below.

[0118] Table 3

[0119]

[0120] It can be seen from the data in Table 3 that the copper foil surface treatment process disclosed in the present invention has universality. The copper foil treated by this process can significantly improve its peel strength with various resin substrates, and enhance the heat resistance and aging resistance of the copper clad laminate.

[0121] The above-disclosed are preferred embodiments, but the protection scope of the present invention is not limited thereto. Those of ordinary skill in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes, but as long as they do not depart from the spirit of the present invention, they are within the protection scope of the present invention.

Claims

1. A surface treatment process for copper foil, comprising sequentially performing pickling, rough curing, anti-oxidation treatment and silanization treatment on the raw foil, characterized in that: The silanization treatment specifically includes: The silane coupling agent, the surfactant and the cross-linking agent are mixed with water, and after being fully hydrolyzed, they are coated on the treated surface of the copper foil, and then dried to obtain the copper foil; The silane coupling agent is selected from vinylbenzyl silane coupling agents; The vinylbenzyl silane coupling agent is selected from KH-6032 and / or SKT1-5132; The surfactant is selected from nonionic surfactants; The nonionic surfactant is selected from ZY-1604 acetylene alcohol polyether surfactant and / or LAE-9 polyoxyethylene fatty acid ester surfactant; The cross-linking agent is selected from amine cross-linking agents; The amine cross-linking agent is selected from one or more of diaminodiphenylmethane, diaminodiphenyl sulfone, m-xylene diamine, m-aminobenzylamine, and 2,6-diaminopyridine; The mass ratio of surfactant to silane coupling agent is 1:(10~50); The mass ratio of the crosslinking agent to the silane coupling agent is 1:(10~50); The mass ratio of silane coupling agent to water is (0.5~5.0):

100.

2. The surface treatment process of copper foil according to claim 1, characterized in that: The rough curing treatment includes a roughening treatment and a curing treatment; The anti-oxidation treatment is specifically to electroplate a metal layer on the rough foil after the rough curing treatment.

3. The surface treatment process of copper foil according to claim 2, characterized in that: The electroplated metal layer includes an electroplated metal nickel layer and an electroplated metal zinc layer; When electroplating a metal nickel layer, the nickel ion concentration in the plating solution is 10~25 g / L, the potassium pyrophosphate concentration is 30~70 g / L, and the current density is 0.4~2.0 A / dm 2 ; When electroplating the metal zinc layer, the zinc ion concentration in the plating solution is 20~40 g / L, the potassium pyrophosphate concentration is 30~70 g / L, and the current density is 0.5~2.5 A / dm 2 .

4. A copper foil prepared according to the surface treatment process according to any one of claims 1 to 3.

5. Use of the copper foil according to claim 4 in preparing PCB copper clad laminate.

6. The use of the copper foil according to claim 5 in preparing a PCB copper-clad laminate, characterized in that: The raw materials include copper foil and a resin substrate, and the resin substrate is selected from one or more of polyphenylene ether, polytetrafluoroethylene and epoxy resin.

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