A carrier copper foil and a preparation method of a copper-clad plate thereof

Abstract

The present application relates to a kind of carrier copper foil and its preparation method of copper-clad plate, different from the structure of conventional carrier copper foil, the present application only includes carrier copper layer, release layer and roughening treatment layer in carrier copper foil, and is peeled after being pressed with resin plate material, only roughened copper tumor embedded in resin is reserved, release layer, carrier copper layer is separated from resin.The present application expands the compatibility of the same carrier copper foil, avoids the separation step of ultra-thin copper layer and carrier copper layer, reduces the surface defects of ultra-thin copper layer caused by separation, and has good application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of copper foil processing, and particularly relates to a carrier copper foil and a preparation method of a copper-clad plate thereof. BACKGROUND

[0002] Since the invention of electronic computers in 1946, the functions of electronic device terminals have been continuously enriched, and the device computing power has been rapidly improving. High integration and precision have been the goals pursued by the electronic circuit industry since the beginning. As the basic material of PCB (Printed Circuit Board), the thickness, roughness, tensile strength, and elongation of copper foil will affect the processing and performance of PCB. Among them, the thickness of copper foil has a particularly significant impact on the line width and line spacing of PCB products. The development of carrier copper foil with a thickness of less than 5 μm has enabled the production of integrated and precise circuit boards to reach a new level.

[0003] Due to the limitations of the production processes of rolled copper foil and traditional electrolytic copper foil, when the thickness of copper foil is less than 5 μm, the production, storage, and transportation of copper foil become extremely difficult due to its insufficient mechanical properties. Therefore, people consider producing ultra-thin copper foil with a thickness of less than 5 μm attached to conventional thickness copper foil (such as 18 μm) together, and then stripping the conventional thickness copper foil when the copper foil is delivered to downstream manufacturers for use, which is called carrier copper foil.

[0004] After decades of development, there are currently many specifications of carrier copper foil, such as 35+5 μm, 18+1.5 μm, 18+2 μm, and 18+3 μm. The structure of carrier copper foil includes a carrier copper layer as a support, a stripping layer providing peelability, an ultra-thin copper layer as the main body for use, and a tumor treatment layer on the surface. The thickness specification of carrier copper foil is fixed during copper foil production, and the thickness of the ultra-thin copper layer cannot be flexibly adjusted during downstream processing. It can be imagined that when the thickness of ultra-thin copper foil continues to be reduced or other surface treatment processes begin to be distinguished, the specifications of carrier copper foil will become more and more numerous, and the high price of carrier copper foil will greatly extend the test cycle and use threshold. Secondly, the core technology of carrier copper foil lies in the construction of the stripping layer. An excellent stripping layer structure has uniform interlayer separation force at room temperature and after high-temperature pressing, and the ultra-thin copper layer is subjected to a small tearing force and no defects are generated. Improper stripping layer structure can cause problems such as the inability to separate the copper layers, uneven separation force, and tearing of the ultra-thin copper layer during stripping, resulting in local pinholes or abnormal separation interfaces. This affects the stripping performance, which can only be solved by adjusting the stripping layer under the existing structure, but there is currently not much related research. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a carrier copper foil and a preparation method of a copper-clad plate thereof, which avoids the peeling step of the ultra-thin copper layer and the carrier copper layer, and reduces the generation of surface defects and abnormalities of the ultra-thin copper layer.

[0006] The present application provides a preparation method of a carrier copper foil, comprising the following steps:

[0007] (1) preparing a carrier copper layer as a support, and pre-treating the carrier copper layer with a mixed solution of sulfuric acid and hydrogen peroxide;

[0008] (2) electrochemically depositing a peeling layer on the surface of the carrier copper layer by using a non-copper metal electroplating treatment technology;

[0009] (3) performing roughening treatment on the surface of the carrier copper layer on which the peeling layer is deposited, and finally performing silane coating treatment on the surface of the carrier copper layer to obtain a carrier copper foil.

[0010] Preferably, the thickness of the carrier copper layer in step (1) is between 12-35 μm, and the copper layer smoothness roughness Rz is between 0.9-1.5 μm.

[0011] Preferably, the concentration of the mixed solution of sulfuric acid and hydrogen peroxide in step (1) is between 40-80 g / L, the volume ratio of hydrogen peroxide to sulfuric acid is between 0.1-0.3, and the pre-treatment time is between 5-10 s.

[0012] Preferably, the non-copper metal electroplating treatment technology in step (2) is specifically as follows: 2-5 times of non-copper metal deposition is performed on the surface of the pre-treated carrier copper layer by using a direct current power supply, the current density is between 0.15-1.00 A / dm 2 , the electrolyte temperature is 40-50℃; and an organic peeling layer is coated on the surface of the non-copper metal after the deposition is completed, and the hot air oven baking temperature is 150-180℃.

[0013] Preferably, the organic peeling layer is one or more of methyl methacrylate chromium chloride, dialkyldithiophosphoric acid molybdenum oxide, and dichloroethyl aluminum, and the concentration of each additive is between 5-40 ppm.

[0014] Preferably, the roughening treatment in step (3) is specifically as follows: 2-6 times of roughening and solidification treatment is performed on the surface of the carrier copper layer in an electroplating solution containing additives, the roughening current density is between 14-30 A / dm 2 , the solidification current density is between 12-45 A / dm 2 , and the ratio of the roughening current density to the solidification current density is between 0.7-1.5.

[0015] Preferably, the process conditions of the silane coating treatment in step (3) are: the silane concentration is 0.9±0.1wt%, and the hot air oven baking temperature is 120-130℃.

[0016] Preferably, the silane coupling agent used in the silane coating treatment is one or more of KH-550, KBM-403, and KBM-903.

[0017] Preferably, the roughness Rz of the treated surface of the carrier copper layer is between 0.6-1.5μm, the roughness Rz of the treated surface after the peeling layer is attached thereto is between 0.6-1.6μm, and the roughness Rz of the roughened surface of the finished carrier copper foil is between 1.3-2.5μm.

[0018] Preferably, the copper tumors of the roughened surface of the carrier copper foil are densely distributed, the average curvature radius Spc of the surface features of the peak points is between 57.7-112.11 / mm, the surface feature density Spd of the peak points is between 33100-74100 1 / mm 2 , and the copper tooth height is between 0.5-1.5μm.

[0019] The present application also provides a method for preparing a copper-clad plate, comprising the following steps:

[0020] (1) performing a plate hot-pressing treatment by bonding the obtained carrier copper foil with a resin plate material;

[0021] (2) peeling the carrier copper foil from the resin plate material, leaving the roughened copper tumors embedded in the resin, to obtain a resin plate material with embedded roughened copper tumors;

[0022] (3) electrodepositing an ultra-thin copper layer on the surface of the resin plate material with embedded roughened copper tumors, to obtain a copper-clad plate.

[0023] Preferably, the process conditions of the hot-pressing treatment in step (1) are: the temperature is 200-240℃, and the pressure is 40-45kgf / m 2 .

[0024] Preferably, the process conditions of the peeling in step (2) are: the angle is 90°, and the peeling line speed is 40-60mm / min.

[0025] Preferably, the thickness of the ultra-thin copper layer in step (3) is 1.0-5.0μm.

[0026] Preferably, the process conditions of the electrodepositing in step (3) are: the electrolyte temperature is 50±1℃, and the electrodeposition current density is between 150-400A / dm 2 .

[0027] The present application also provides a copper-clad plate prepared by the above-mentioned method.

[0028] Advantageous effects

[0029] The carrier copper foil of the present application only comprises a carrier copper layer, a stripping layer and a surface treatment copper layer, and the ultra-thin copper layer is prepared by electrodeposition after pressing and stripping with resin. The preparation technology proposed by the present application has the following characteristics: 1. Higher thickness compatibility of the carrier copper layer, the thickness of the carrier copper layer is between 12-35 μm, and the surface roughness Rz is between 0.6-1.5 μm, which widens the type of carrier used; 2. Simplified structure of the carrier copper foil, which reduces the lengthy production process. Different from the conventional carrier copper foil structure, the present application only comprises a carrier copper layer, a stripping layer and a roughening treatment layer in the finished copper foil, and only the surface treatment copper tumor is embedded in the resin after pressing with the resin plate, and the stripping layer and the carrier copper layer are separated from the resin; 3. Dense distribution of surface copper tumor, in order to ensure the stable progress of the subsequent thickening process, the compact structure of the roughened copper tumor, the roughness Rz is between 1.3-2.5 μm, the Sz is between 1.2-4.0 μm, the average curvature radius Spc of the surface feature peak is between 57.7-112.1 1 / mm, the surface feature density Spd of the peak point is between 33100-74100 1 / mm 2 ; 4. Higher peel strength, the finished foil and the bismaleimide triazine BT resin plate are laminated at 240℃ under a pressure of 45kgf / m 2 , and the copper-clad plate is thickened to 35 μm, and the peel strength is not less than 0.6 N / mm; 5. Excellent performance regulation of ultra-thin copper layer, the construction of ultra-thin copper layer is carried out after pressing the plate, and its thickness can be flexibly thickened to 1.5-5.0 μm according to the needs of mSap process, which expands the compatibility of the same carrier copper foil, avoids the separation step of ultra-thin copper layer and carrier copper layer, and reduces the surface defects caused by the separation of ultra-thin copper layer. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The flow chart for preparing carrier copper foil of the present application and prior art; wherein, 1-roughening layer; 2-ultra-thin copper layer; 3-stripping layer; 4-carrier copper layer.

[0031] Figure 2 The flow chart for preparing copper-clad plate of the present application and prior art; wherein, 5-resin plate.

[0032] Figure 3 The pinhole photo of the ultra-thin copper layer prepared in Example 1(a) and Comparative Example 1(b). DETAILED DESCRIPTION

[0033] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not used to limit the scope of the application. Furthermore, it should be understood that after reading the content of the application, those skilled in the art can make various modifications or changes to the application, and these equivalent forms also fall within the scope of the appended claims.

[0034] Example 1

[0035] 1. Preparation of carrier copper layer

[0036] A mixed solution of H2SO4, CuSO4 and HCl is used as electrolyte, and direct current power is used to perform electrolytic deposition of the carrier copper layer on the surface of the cathode roller at a certain temperature. The thickness of the prepared carrier copper layer is 18 μm, and the roughness Rz of the copper layer is less than 2.5 μm. The parameters of the electrolytic process are as follows:

[0037] H2SO4 concentration: 125 g / L

[0038] Cu 2+ ion concentration: 100 g / L

[0039] Cl － ion concentration: 10 mg / L

[0040] Current size: 38 A / dm 2

[0041] Electrolyte temperature: 55°C

[0042] Electrolyte flow rate: 15 m 3 / h

[0043] Cathode roller linear speed: 9.0 m / min.

[0044] 2. Pretreatment of carrier copper layer

[0045] A combined solution of H2SO4 and H2O2 is used as pretreatment solution, and the copper foil is immersed for surface pretreatment to remove the surface oxide layer and impurities. The thickness of the copper layer of the copper foil after treatment is unchanged, and the roughness Rz of the surface is less than 2.5 μm. The parameters of the pretreatment process are as follows:

[0046] H2SO4 concentration: 60 g / L

[0047] H2O2 concentration: 25 wt%

[0048] Pretreatment solution temperature: 35°C

[0049] Pretreatment solution flow rate: 10 m 3 / h

[0050] Treatment time: 15 s.

[0051] 3. Stripping layer construction

[0052] The stripping layer is constructed by non-copper metal and organic coupling agent to provide stable stripping performance. The specific parameters of the stripping layer deposition and coating process are as follows:

[0053] (1) Electrodeposition of nickel-containing stripping layer

[0054] Ni 2+ Concentration: 0.5 g / L

[0055] K4P2O7 concentration: 10 g / L

[0056] PH value: 11

[0057] Current density: 0.15 A / dm 2

[0058] Electrolyte temperature: 40℃.

[0059] (2) Electrodeposition of zinc-containing stripping layer

[0060] Zn 2+ Concentration: 0.5 g / L

[0061] K4P2O7 concentration: 20 g / L

[0062] PH value: 11

[0063] Current density: 0.3 A / dm 2

[0064] Electrolyte temperature: 40℃.

[0065] (3) Organic stripping layer coating

[0066] Chromium methacrylate concentration: 30 ppm

[0067] Coating time: 5 s

[0068] Solution temperature: 45℃

[0069] Baking temperature: 130℃.

[0070] 4. Surface roughening treatment

[0071] In the present invention, the surface roughening treatment of copper tumors not only serves to enhance the bonding force between the copper foil and the resin board, but also after stripping the carrier copper layer, it will be embedded in the resin board as an ultra-thin copper layer electrodeposition substrate. The surface roughening treatment process is divided into roughening treatment and solidification treatment. The roughening treatment is used to generate fine copper tumor crystals on the surface of the stripping layer, and the solidification treatment is used to allow the crystals to continue to grow. The two roughening treatments are carried out in different electrolytes, and the roughening and solidification treatments are alternately repeated 2 times. The specific parameters of the roughening treatment process are as follows:

[0072] (1) Roughening treatment parameters

[0073] Cu 2+ Ion concentration: 13 g / L

[0074] H2SO4 concentration: 110 g / L

[0075] Roughening solution temperature: 30°C

[0076] Roughening solution flow rate: 11.0 m 3 / h

[0077] Average current density: 14 A / dm 2

[0078] Treatment time: 10 s.

[0079] (2) Solidification treatment parameters

[0080] Cu 2+ Ion concentration: 45 g / L

[0081] H2SO4 concentration: 90 g / L

[0082] Solidification solution temperature: 50°C

[0083] Roughening solution flow rate: 11.0 m 3 / h

[0084] Average current density: 12 A / dm 2

[0085] Treatment time: 10 s.

[0086] In addition to the surface roughening treatment, in order to extend the oxidation resistance and shelf life of the copper foil, a non-copper metal is also electroplated on the roughened copper tumor surface. The specific parameters of the treatment process are as follows:

[0087] Electrodeposition of nickel-containing oxidation-resistant layer

[0088] Ni 2+ Concentration: 1.5 g / L

[0089] K4P2O7 concentration: 20 g / L

[0090] pH: 11

[0091] Current density: 0.5 A / dm 2

[0092] Electrolyte temperature: 40°C

[0093] Treatment time: 10 s.

[0094] 5. Silane coupling agent coating

[0095] Silane coupling agent coating is mainly used to further enhance the bonding force of copper foil and resin plate. In the present application, the method of spraying + roller coating is used to coat the silane coupling agent on the roughened surface. The specific parameters of the coating process are as follows:

[0096] KH-550 silane concentration: 0.9wt%

[0097] Silane solution temperature: 27℃

[0098] Silane solution flow rate: 4.0m 3 / h

[0099] Baking temperature: 140℃.

[0100] 6. High temperature pressing of copper foil and resin plate

[0101] High temperature pressing of copper foil and resin plate is mainly used to embed roughened copper tumors. Under high temperature conditions, the resin plate shows fluidity and closely adheres to the copper foil. After cooling, it forms an embedded structure with the roughened copper tumor. The specific parameters of the high temperature pressing process are as follows:

[0102] Prepreg model: bismaleimide triazine BT resin

[0103] Pressing temperature: 240℃

[0104] Soaking time: 180min

[0105] Unit area pressure: 45kgf / m 2 .

[0106] 7. Separation of copper foil and resin plate

[0107] In the present application, the separation process separates the carrier copper layer in the carrier copper foil structure from the interface of the peeling layer and the roughened copper tumor. The roughened copper tumor will remain in the cured resin plate. The specific parameters of the separation process are as follows:

[0108] Peeling angle: 90°

[0109] Peeling speed: 50mm / min

[0110] Foil surface tension: 60N.

[0111] 8. Electrodeposition of ultra-thin copper layer

[0112] In the present application, the ultra-thin copper layer is made in this process. The roughened copper tumor embedded in the resin plate is used as a seed layer to achieve electroplating of the ultra-thin copper layer, and a copper-clad plate is made. The specific parameters of electrodeposition are as follows:

[0113] Cu 2+ Ion concentration: 85g / L;

[0114] H2SO4 concentration: 100 g / L;

[0115] Cl - Ion concentration: 30 mg / L;

[0116] Gum arabic: 40 ppm.

[0117] Example 2

[0118] The difference between this example and Example 1 is that (1) the current density of the carrier copper layer is adjusted, and the thickness of the carrier copper layer is 12 μm; (2) the current density for preparing the metal stripping layer is adjusted, and is changed from 0.15 A / dm 2 to 1.00 A / dm 2 ; (3) the type of the organic stripping layer material is adjusted, and is changed to dialkyldithiophosphoric acid oxymolybdenum; (4) the type of the silane coating on the surface of the finished foil is adjusted, and KH-550 is changed to KBM-403.

[0119] Example 3

[0120] The difference between this example and Example 1 is that (1) the current density of the carrier copper layer is adjusted, and the thickness of the carrier copper layer is 35 μm; (2) the type of the organic stripping layer material is adjusted, and is changed to dialkyldithiophosphoric acid oxymolybdenum and dichloroethyl aluminum; (3) the type of the silane coating on the surface of the finished foil is adjusted, and KH-550 is changed to KBM-903; (4) the thickness of the ultra-thin copper layer is adjusted, and is changed from 2 μm to 1.5 μm.

[0121] Example 4

[0122] The difference between this example and Example 1 is that (1) the roughening copper tumor treatment process is adjusted, in which the roughening current density is 30 A / dm 2 and the solidification current density is 45 A / dm 2 ; (2) the type of the organic stripping layer material is adjusted, and is changed to methacrylic acid chromium chloride and dialkyldithiophosphoric acid oxymolybdenum; (3) the thickness of the ultra-thin copper layer is adjusted, and is changed from 2 μm to 5 μm.

[0123] Comparative Example 1

[0124] The difference between this comparative example and Example 1 is that (1) the step 8 ultra-thin copper layer deposition is moved to between the step 3 stripping layer construction and the step 4 surface roughening treatment, i.e. the ultra-thin copper layer is electroplated on the surface of the stripping layer, rather than the resin-embedded copper tumor surface after pressing.

[0125] Comparative Example 2

[0126] The difference between the present comparative example and Example 2 is that (1) the step 8 ultra-thin copper layer deposition is moved between the step 3 release layer construction and the step 4 surface roughening treatment, that is, the ultra-thin copper layer is electroplated on the surface of the release layer, instead of the resin-embedded copper tumor surface after the pressing.

[0127] Comparative Example 3

[0128] The difference between the present comparative example and Example 3 is that (1) the step 8 ultra-thin copper layer deposition is moved between the step 3 release layer construction and the step 4 surface roughening treatment, that is, the ultra-thin copper layer is electroplated on the surface of the release layer, instead of the resin-embedded copper tumor surface after the pressing.

[0129] Comparative Example 4

[0130] The difference between the present comparative example and Example 4 is that (1) the step 8 ultra-thin copper layer deposition is moved between the step 3 release layer construction and the step 4 surface roughening treatment, that is, the ultra-thin copper layer is electroplated on the surface of the release layer, instead of the resin-embedded copper tumor surface after the pressing.

[0131] Main parameters of Examples and Comparative Examples in Table 1

[0132]

[0133]

[0134] Performance comparison of copper foil prepared in Examples and Comparative Examples in Table 2

[0135]

[0136] The preparation method of the carrier copper foil and the copper-clad plate thereof of the present application focuses on that the ultra-thin copper layer used as the main body is prepared after the copper foil is pressed with the resin, and the specific implementation process is as shown in Figure 1 、 Figure 2 The main preparation process of the comparative examples is the process of the prior art, and the main preparation process of the examples is the process of the present patent. As can be seen from Table 2, the carrier copper foil samples used in each example meet the requirements of the preparation method in the present application, and under this manufacturing method, the peeling process between the ultra-thin copper layer and the carrier copper layer can be avoided, and good results are obtained in the pinhole test. In Comparative Examples 1, 2, 3 and 4, except for the preparation sequence of the ultra-thin copper layer, the other steps are one-to-one corresponding to Examples 1, 2, 3 and 4. As a result, the results in the pinhole test are not good, and there are a large number of pinholes as shown in Figure 3 , which makes there is a great risk of short circuit when manufacturing fine lines on the copper-clad plate and PCB.

Claims

1. A method for preparing a carrier copper foil, comprising the following steps: (1) preparing a carrier copper layer as a support, and pre-treating the carrier copper layer with a mixed solution of sulfuric acid and hydrogen peroxide; (2) electrochemically depositing a release layer on the surface of the carrier copper layer by using a non-copper metal electroplating treatment technology; (3) performing roughening treatment on the surface of the release layer to form copper tumors, and performing silane coating treatment on the roughened surface to obtain a carrier copper foil.

2. The method of claim 1, wherein: The thickness of the carrier copper layer in the step (1) is between 12-35 μm, and the copper layer smoothness roughness Rz is between 0.9-1.5 μm.

3. The method of claim 1, wherein: The non-copper metal electroplating treatment technology in the step (2) is specifically: using a direct current power source to perform 2-5 times of non-copper metal deposition on the surface of the pretreated carrier copper layer, the current density is between 0.15-1.00 A / dm 2 , and the electrolyte temperature is 40-50℃; after the non-copper metal deposition is completed, an organic stripping layer is coated on the surface, and the hot air oven baking temperature is 150-180℃.

4. The method of claim 1, wherein: The roughening treatment in step (3) is specifically: 2-6 times of roughening and solidifying treatment is performed on the surface of the carrier copper layer in an electroplating solution containing additives, the roughening current density is between 14-30 A / dm 2 , the solidifying current density is between 12-45 A / dm 2 , and the ratio of roughening and solidifying current is between 0.7-1.

5.

5. The method of claim 1, wherein: The process conditions for the silane coating treatment in the step (3) are as follows: the silane concentration is 0.9±0.1 wt%, and the hot air oven baking temperature is 120-130 °C.

6. A method for preparing a copper-clad plate, comprising the following steps: (1) adhering the carrier copper foil obtained by the method for preparing a carrier copper foil according to claim 1 to a resin plate material to perform plate hot-pressing treatment; (2) separating the carrier copper foil from the resin plate material, and retaining the roughened copper tumors embedded in the resin to obtain a resin plate material embedded with roughened copper tumors; (3) electrodepositing an ultrathin copper layer on the surface of the resin plate material embedded with roughened copper tumors to obtain a copper-clad plate.

7. The method of claim 6, wherein: The process conditions of the heat lamination treatment in the step (1) are: temperature 200-240°C, pressure 40-45 kgf / m 2 .

8. The method of claim 6, wherein: The thickness of the ultrathin copper layer in the step (3) is 1.0-5.0 μm.

9. The method of claim 6, wherein: The process conditions of the electrodeposition in step (3) are: electrolyte temperature of 50±1℃, electrodeposition current density between 150-400 A / dm 2 2.

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