Composite film, copper foil substrate containing composite film and manufacturing method of copper foil substrate

Abstract

The invention discloses a composite film, a copper foil substrate containing the composite film and a manufacturing method thereof, the composite film comprises a support film and an adhesive composition formed on the support film, the adhesive composition comprises polyimide and liquid crystal polymer filler, the polyimide is composed of dianhydride and diamine, and the liquid crystal polymer filler is formed on the support film. The dianhydride at least comprises bisphenol A type diether dianhydride residues (BPADA), the diamine at least comprises diamine with an ether structure, and the liquid crystal polymer filler accounts for 30wt%-50wt% of the weight of the adhesive composition; and wherein the ratio of the glass transition temperature TgB of the polyimide to the melting point temperature TmA of the liquid crystal polymer filler (TgB / TmA) lt; 0.6, so that the dielectric loss (Df) of the composite film is less than 0.005.

Description

Technical Field

[0001] This application relates to the technical field of polyimide films, and specifically relates to a composite film, a copper foil substrate containing the composite film, and a manufacturing method thereof. Background Art

[0002] With the rapid development of high-frequency and high-speed communication applications, and the increasing demand for materials for flexible substrates (FCCL) and printed wiring boards (FPC) suitable for high frequencies and high speeds, fluorine-based polymers are currently the mainstream bulk materials used for high-frequency applications. However, due to the continuous enhancement of environmental awareness (such as the EU's Perfluorinated and Polyfluorinated Alkyl Substances (PFAS) issue), excellent high-frequency application materials that cannot be decomposed for a long time are also being considered not to be widely used in the manufacture of 3C products. Therefore, non-fluorine-based high-frequency materials have become increasingly important. The mainstream non-fluorine-based materials in the market are liquid crystal molecular materials and polyimides.

[0003] The electrical properties of pure liquid crystal polymer materials are excellent, but their adhesion to copper foil, mechanical and thermal properties are poor, resulting in higher technical thresholds, lower yields, and higher prices in the processing of FCCL and FPC, and also causing the market to be monopolized. Polyimide has excellent mechanical and thermal properties required in the processing of FCCL and FPC, and also has good adhesion to copper foil. Almost all FCCL and FPC factories have mature processing technologies. However, its electrical performance is not excellent enough for communication requirements greater than 10 GHz (20 - 100 GHz). Currently, the development of high-frequency polyimide has reached the limit of material properties. To improve high-frequency polyimide, special monomer raw materials must be used, resulting in problems such as increased development costs and low price competitiveness.

[0004] For flexible substrates (FCCL), dielectric loss and adhesion to the copper foil layer are the two most important factors to be considered in the subsequent processing of materials, and they are two important indicators on the material side. In the future, it is necessary to invent a material that simultaneously has these two better properties. Summary of the Invention

[0005] To solve the above deficiencies in the art, this application aims to provide a composite film and a manufacturing method of a copper foil substrate containing the composite film.

[0006] The composite film includes a support film and an adhesive composition, the adhesive composition is formed on the support film, and the adhesive composition includes polyimide and liquid crystal polymer filler;

[0007] The polyimide is composed of dianhydride and diamine, the dianhydride at least includes bisphenol A type diether dianhydride residue (BPADA), and the diamine at least includes diamine with an ether group structure;

[0008] The weight percentage of the liquid crystal polymer filler in the adhesive composition is 30 wt% to 50 wt%; and

[0009] wherein, the ratio (TgB / TmA) of the glass transition temperature TgB of the polyimide to the melting point temperature TmA of the liquid crystal polymer filler is < 0.6, so that the dielectric loss (Df) of the composite film is less than 0.005. Description of the Drawings

[0010] Figure 1 It is a schematic structural diagram of the composite film of the present application.

[0011] Figure 2 It is a schematic diagram of the copper foil substrate containing the composite film of the present application.

[0012] Symbol Description

[0013] Support film 10

[0014] Adhesive composition 11

[0015] Metal copper foil 12 Detailed Embodiments

[0016] Next, the technical solutions of the present application will be clearly and completely described in conjunction with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0017] It should be particularly noted that similar replacements and modifications made to the present application are obvious to those skilled in the art, and they are all considered to be included in the present application. Relevant personnel can obviously make changes or appropriate changes and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present application to implement and apply the technology of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0018] If the present application does not specify specific conditions, they are all carried out according to conventional conditions or conditions recommended by the manufacturer. For the raw materials or auxiliary materials used, and for the reagents or instruments used, if the manufacturer is not specified, they are all conventional products that can be obtained through commercial purchase.

[0019] The present application will be described in detail below.

[0020] Figure 1 It is a schematic structural diagram of the present application. The composite film includes:

[0021] A support film 10, which can be a polyimide film, a composite film of liquid crystal polymer and polyimide, or a composite film of fluoropolymer and polyimide.

[0022] An adhesive composition 11, which is formed on the support film 10 and includes polyimide and liquid crystal polymer fillers. The polyimide is composed of dianhydride and diamine. The dianhydride includes at least bisphenol A type diether dianhydride residue (BPADA), and the diamine includes at least diamine with an ether group structure. The weight percentage of the liquid crystal polymer fillers in the adhesive composition is 30wt% - 50wt%.

[0023] Among them, the ratio (TgB / TmA) of the glass transition temperature TgB of the polyimide to the melting point temperature TmA of the liquid crystal polymer fillers is <0.6, so that the dielectric loss (Df) of the composite film is less than 0.005.

[0024] The diamine containing an ether group structure is defined as having the following molecular structure, R 1 and R 2 are any other chemical structures, and n can be 1 - 2.

[0025]

[0026] The liquid crystal filler optionally has a dielectric loss less than 0.001, preferably less than 0.0009, and more preferably less than 0.0008.

[0027] The liquid crystal filler has a cumulative particle size 50% D50 of the particle size distribution of 20μm or less, and the cumulative particle size 99% D99 is 2.5 times or less of D50.

[0028] The melting temperature (Tm) of the liquid crystal filler optionally ranges from 270 to 330°C, preferably from 300 to 330°C, and more preferably from 310 to 330°C.

[0029] The water absorption rate of the liquid crystal filler is optionally less than 0.5%, and more preferably less than 0.05%.

[0030] After adding a dehydrating agent and a catalyst to the adhesive composition and uniformly mixing them, it is coated on a support film, and then undergoes chemical cyclization or direct thermal hardening without adding a dehydrating agent and a catalyst, and finally is cured by high-temperature baking to form a composite film.

[0031] The dehydrating agent for the above chemical catalytic cyclization can be acetic anhydride; the catalyst can be selected from pyridine, 3-methylpyridine, 2-methylpyridine, 4-methylpyridine, isoquinoline, quinoline, triethylamine, preferably pyridine, 3-methylpyridine, 2-methylpyridine, 4-methylpyridine, and 3-methylpyridine is selected as the catalyst in the exemplary embodiments of this application.

[0032] The high-temperature baking and curing temperature conditions used in the method for manufacturing the composite film can be baking at 80-90°C for 20-40 minutes; heating to 170°C and baking for 20-30 minutes, then heating to 250°C and baking for 30-60 minutes, and finally heating to 310-350°C and baking for 20-30 minutes.

[0033] As Figure 2 shown, it is a schematic structural diagram of the copper foil substrate containing the above composite film of the present application.

[0034] A metal copper foil 12 is pre-pressed on one or both sides of the composite film at a temperature of 320-340°C, and then a copper foil substrate is formed through high-pressure and high-temperature pressing.

[0035] The copper foil can be a rolled copper foil, an electrolytic copper foil, or a copper foil with low surface roughness, and copper foils with various surface treatments (roughening, rust prevention, etc.) can also be used. For rust prevention treatment, electroplating treatments containing Ni, Zn, Sn, etc., chromate treatment, etc. can be used. There is no particular limitation on the copper foil thickness, and it can be optionally 1-100 μm, preferably 1-50 μm.

[0036] The pressure used for pressing the composite film is 60 kgf / cm 2 、the temperature can be optionally 280-340°C, preferably 320-340°C, for a duration of 20 minutes, and then the temperature is lowered to 180-200°C, the pressure is 15-20 kgf / cm 2 、for a duration of 10 minutes, and the actual temperature can be finely adjusted according to the glass transition temperature TgB.

[0037] The following specifically describes the present application in conjunction with embodiments. The following are the raw materials represented by abbreviations in each embodiment.

[0038] Abbreviation of the raw materials of the adhesive composition:

[0039] Bisphenol A diether dianhydride: BPADA

[0040] 3,3’,4,4’-Biphenyltetracarboxylic dianhydride: BPDA

[0041] Pyromellitic dianhydride: PMDA

[0042] Diamine containing an ether group structure: TPER, TPEQ, APBN

[0043] 4,4’-Diaminodiphenyl ether residue: ODA

[0044] p-Phenylenediamine: PDA

[0045] Liquid crystal filler: LF-31P liquid crystal polymer powder, developed and manufactured by ENEOS Corporation

[0046] Solvent

[0047] DMAc: N,N-Dimethylacetamide

[0048] AA: Acetic anhydride

[0049] AP: 3-Methylpyridine

[0050] <Testing method>

[0051] The properties of the adhesive composition, multi-layer film, and copper-clad laminate obtained in the following examples were measured using the following methods.

[0052] Dielectric loss: According to the ASTM D2520 standard method, using an E5071C network analyzer manufactured by Agilent Technologies, and the resonator is distributed by Viavi Solutions. The measurement was carried out at a relative humidity of 50%RH and a frequency of 10 GHz. The average value of three measurements was taken as the actual value.

[0053] Glass transition temperature (TgB): According to the IPC-TM-650 specification, using a Q400 TMA instrument manufactured by TA Instruments, and the heating rate was set at 10°C / min for measurement.

[0054] Melting temperature (TmA): According to the ASTM D3418 specification, using a DSC200F3 instrument manufactured by NETZSCH for scanning measurement.

[0055] Peel strength: According to the IPC TM 650 specification, using a 10ST universal material testing machine manufactured by Tinius Olsen for measurement.

[0056] Example 1

[0057] Preparation of composite film

[0058] To polymerize 120 g of a polyimide precursor: 12.1 g of APBN was added to 86.4 g of DMAc solvent, stirred and dissolved evenly, then 21.0 g of BPADA was added. The reaction temperature was controlled at 25°C, and the reaction was continuously stirred for 2 - 3 hours. A small amount of BPADA was used to finely adjust the viscosity. Finally, a polyimide precursor with a solid content of 28.0% and a viscosity of 160000 ± 40000 cps was obtained.

[0059] 25.0 g of polyimide precursor, 25.1 g of DMAc solvent and 3.0 g of liquid crystal filler were mixed and stirred evenly. A catalyst and dehydrating agent mixture was added to the adhesive composition. The catalyst mixture was composed of a mixture of 2.7 g of AA, 1.3 g of AP and 4.0 g of DMAc solution. Finally, an adhesive composition with a total solid content of 16.5% was obtained. After uniform mixing, it was defoamed by centrifugation and coated on a support film (a polyimide film was used here). It was baked at 80 - 90 °C for 20 minutes, heated to 170 °C and baked for 30 minutes, then heated to 250 °C and baked for 60 minutes, and finally heated to 330 °C and baked for 20 minutes to form a composite film.

[0060] Copper foil substrate production

[0061] A composite film with a length and width of 10 cm was taken, and both sides of the composite film were covered with copper foil with a length and width of 15 cm. After being laminated under the conditions of a pressure of 60 kgf / cm 2 、a temperature of 310 °C for 15 minutes, then the temperature was lowered to 190 °C and the pressure was 15 kgf / cm 2 、and laminated for 10 minutes, and finally a copper foil substrate was formed.

[0062] Example 2

[0063] The production of the composite film was the same as in Example 1, but the weight of the added liquid crystal filler was changed to 4.7 g.

[0064] The production of the copper foil substrate was the same as in Example 1.

[0065] Example 3

[0066] The production of the composite film was the same as in Example 1, but the weight of the added liquid crystal filler was 7.2 g.

[0067] The production of the copper foil substrate was the same as in Example 1.

[0068] Example 4

[0069] The production of the composite film was the same as in Example 1, but 12.1 g of APBN was changed to add 12.1 g of TPER.

[0070] The production of the copper foil substrate was the same as in Example 1.

[0071] Example 5

[0072] The production of the composite film was the same as in Example 1, but 12.1 g of APBN was changed to add 12.1 g of TPEQ, and the weight of the added liquid crystal filler was 7.2 g.

[0073] The production of the copper foil substrate was the same as in Example 1.

[0074] Example 6

[0075] The composite film was fabricated in the same manner as in Example 1, except that 12.1 g of APBN was replaced with 11.2 g of TPER and 0.4 g of PDA, and the weight of the liquid crystal filler added was 7.2 g.

[0076] The copper foil substrate was fabricated in the same manner as in Example 1.

[0077] Example 7

[0078] The composite film was fabricated in the same manner as in Example 1, except that 12.1 g of APBN was replaced with 11.5 g of TPER and 0.3 g of PDA, and the weight of the liquid crystal filler added was 7.2 g.

[0079] The copper foil substrate was fabricated in the same manner as in Example 1.

[0080] Example 8

[0081] The composite film was fabricated in the same manner as in Example 1, except that 12.4 g of TPER, 20.0 g of BPADA and 1.1 g of BPDA were added, and the weight of the liquid crystal filler added was 7.2 g.

[0082] The copper foil substrate was fabricated in the same manner as in Example 1.

[0083] Example 9

[0084] The composite film was fabricated in the same manner as in Example 1, except that 12.4 g of TPER, 20.1 g of BPADA, 0.57 g of BPDA and 0.42 g of PMDA were added, and the weight of the liquid crystal filler added was 7.2 g.

[0085] The copper foil substrate was fabricated in the same manner as in Example 1.

[0086] Example 10

[0087] The composite film was fabricated in the same manner as in Example 1, except that 12.3 g of TPER, 20.1 g of BPADA and 0.74 g of BPDA were added, and the weight of the liquid crystal filler added was 7.2 g.

[0088] The copper foil substrate was fabricated in the same manner as in Example 1.

[0089] Example 11

[0090] The composite film was fabricated in the same manner as in Example 1, except that 11.4 g of TPER, 0.5 g of ODA and 21.7 g of BPADA were added, and the weight of the liquid crystal filler added was 7.2 g.

[0091] The copper foil substrate was fabricated in the same manner as in Example 1.

[0092] Example 12

[0093] The composite film was fabricated in the same manner as in Example 1, except that 9.7 g of TPER, 3.3 g of ODA, 1.8 g of PDA, and 18.9 g of BPADA were added, and the weight of the liquid crystal filler added was 7.2 g.

[0094] The copper foil substrate was fabricated in the same manner as in Example 1.

[0095] Comparative Example 1

[0096] The composite film was fabricated in the same manner as in Example 1, except that the weight of the liquid crystal filler added was 1.8 g.

[0097] The copper foil substrate was fabricated in the same manner as in Example 1.

[0098] Comparative Example 2

[0099] The composite film was fabricated in the same manner as in Example 1.

[0100] The copper foil substrate was fabricated in the same manner as in Example 1, except that the maximum lamination temperature was 310 °C.

[0101] Comparative Example 3

[0102] The composite film was fabricated in the same manner as in Example 1.

[0103] The copper foil substrate was fabricated in the same manner as in Example 1, except that the maximum lamination temperature was 350 °C.

[0104] Comparative Example 4

[0105] The composite film was fabricated in the same manner as in Example 1, except that the weight of the liquid crystal filler added was 16.8 g.

[0106] The copper foil substrate was fabricated in the same manner as in Example 1.

[0107] Comparative Example 5

[0108] The composite film was fabricated in the same manner as in Example 1, except that 10.1 g of TPER, 0.9 g of PDA, and 22 g of BPADA were added.

[0109] The copper foil substrate was fabricated in the same manner as in Example 1.

[0110] Comparative Example 6

[0111] The composite film was fabricated in the same manner as in Example 1, except that 13.1 g of TPER, 1.9 g of PMDA, and 18.6 g of BPADA were added.

[0112] The copper foil substrate was fabricated in the same manner as in Example 1.

[0113] The comparison between the examples and comparative examples is shown in the following table:

[0114] Table 1

[0115]

[0116]

[0117] Comparative Example 1: Since the solid weight percentage of the added liquid crystal filler is less than 30%, its dielectric loss is greater than 0.005.

[0118] Comparative Example 2: Since the maximum lamination temperature is less than 320 °C, its peel strength is less than 0.8 Kgf / cm.

[0119] Comparative Example 3: Since the maximum lamination temperature is greater than 340 °C, its peel strength is less than 0.8 Kgf / cm.

[0120] Comparative Example 4: Since the solid weight percentage of the added liquid crystal filler is greater than 50%, its peel strength is less than 0.8 Kgf / cm.

[0121] Comparative Example 5: Since the molar percentage of the added diamine without an ether group structure is greater than 20%, its dielectric loss is greater than 0.005 and its peel strength is less than 0.8 Kgf / cm.

[0122] Comparative Example 6: Since the molar percentage of the added PMDA dianhydride is greater than 20%, its dielectric loss is greater than 0.005 and its peel strength is less than 0.8 Kgf / cm.

[0123] As shown in Table 1, it can be confirmed that the adhesive composition manufactured according to the embodiments of the present invention forms a multilayer film having a characteristic of a dielectric loss less than 0.0055, and the peel strength between the multilayer film and the copper foil of the copper-clad laminate formed by laminating the multilayer film is greater than 0.8 Kgf / cm.

[0124] The description of the above embodiments is only used to help understand the method and its core idea of the present application. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A composite film, characterized in that, The composite film includes: A support film; An adhesive composition formed on the support film, the adhesive composition including a polyimide and a liquid crystal polymer filler, the polyimide being composed of a dianhydride and a diamine, the dianhydride including a bisphenol A type diether dianhydride residue, the diamine including a diamine having an ether group structure, the liquid crystal polymer filler accounting for 30wt% - 50wt% of the weight of the adhesive composition; and Wherein, the ratio (TgB / TmA) of the glass transition temperature TgB of the polyimide to the melting point temperature TmA of the liquid crystal polymer filler is < 0.6, so that the dielectric loss of the composite film is less than 0.

005.

2. The composite film according to claim 1, characterized in that, The support film is a polyimide film.

3. The composite film according to claim 1, characterized in that, The dianhydride further includes a pyromellitic dianhydride residue, The mole percentage of the pyromellitic dianhydride residue in the dianhydride is less than 10%.

4. The composite film according to claim 1, wherein, The dianhydride further includes a 3,3’,4,4’-biphenyltetracarboxylic dianhydride residue, and the mole percentage of the 3,3’,4,4’-biphenyltetracarboxylic dianhydride residue in the dianhydride is less than 10%.

5. The composite film according to claim 1, wherein The dianhydride further includes a 3,3’,4,4’-biphenyltetracarboxylic dianhydride residue and a pyromellitic dianhydride residue, The total mole percentage of the 3,3’,4,4’-biphenyltetracarboxylic dianhydride residue and the pyromellitic dianhydride residue in the dianhydride is less than 10%.

6. The composite film according to claim 1, wherein The diamine further includes a 4,4’-diaminodiphenyl ether residue, and the mole percentage of the 4,4’-diaminodiphenyl ether residue in the diamine is less than 10%.

7. The composite film according to claim 1, characterized in that, The diamine further includes a p-phenylenediamine residue, and the mole percentage of the p-phenylenediamine in the diamine is less than 10%.

8. The composite film according to claim 1, wherein The diamine further includes a 4,4’-diaminodiphenyl ether residue and a p-phenylenediamine residue, and the total mole percentage of the 4,4’-diaminodiphenyl ether residue and the p-phenylenediamine in the diamine is less than 10%.

9. A method for manufacturing a copper foil substrate containing the composite film according to any one of claims 1-8, characterized in that, Including: Providing a composite film; and Providing a copper foil, pre-pressing the copper foil on one or both sides of the composite film at a temperature of 320 - 340°C, so that its peel strength is greater than 0.8 Kgf / cm.

10. A copper foil substrate prepared by the preparation method described in claim 9.

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