Adhesive, preparation method thereof and chemical gold-resistant high-frequency cover film prepared from adhesive

Abstract

The invention discloses an adhesive and a preparation method thereof, and a chemical gold-resistant high-frequency cover film prepared from the adhesive, the adhesive provided by the invention comprises the following components in parts by weight: 800-1200 parts of polyimide resin emulsion, 110-180 parts of epoxy resin emulsion, 120-190 parts of silica powder, 28-36 parts of epoxy curing agent emulsion and 36-45 parts of BMI curing agent emulsion, the acid value of the polyimide resin in the polyimide resin emulsion is 0.07 to 0.12 mol / kg. The invention also provides a preparation method of the adhesive, which specifically comprises the following steps: uniformly mixing the polyimide resin emulsion, the epoxy resin emulsion, the silica powder, the epoxy curing agent emulsion and the BMI curing agent emulsion, and uniformly stirring at 20-35 DEG C for 3-5 hours. The invention also provides a chemical gold-resistant high-frequency cover film which comprises a thin film layer and an adhesive layer formed by coating the adhesive prepared by the invention on the lower surface of the thin film layer, and a release layer is adhered below the adhesive layer.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of adhesives, and particularly relates to an adhesive, a preparation method thereof, and a high-frequency covering film resistant to chemical gold prepared from the adhesive. BACKGROUND

[0002] Printed circuit boards (PCB for short) are important connection and assembly platforms for electronic products, and are considered as the "mother of electronic system products". They have a broad demand market and are applied in fields such as consumer electronics, computers, communications, industrial control, medical instruments, automotive electronics, national defense, and aerospace. Covering film is a very important raw material for printed circuit boards, and the insulating base film and adhesive are the main components of the covering film. The adhesive is a medium for bonding the insulating base film material and the copper foil, and the performance of the adhesive can directly determine the overall performance of the copper-clad plate.

[0003] At present, the global unmanned vehicle industry is developing well, and the market of millimeter wave radar, an important component of unmanned vehicles, is rapidly expanding. In the manufacturing materials of millimeter wave radar, there are high requirements for covering films in the chemical nickel gold (ENIG) process. Because the covering film may appear plating penetration after chemical nickel gold, which can not effectively protect the copper wire from oxidation. The nickel layer in the chemical nickel gold plating layer of the high-frequency covering film on the market is easy to oxidize in a high-temperature or humid environment during the processing of the flexible printed circuit board, resulting in a green or black surface phenomenon. In the chemical nickel gold plating layer of the fine line (line distance < 20 um), the oxidation layer may be too thick, causing short circuit between lines, resulting in low yield during production. In this case, the short board that restricts the use of flexible printed circuit boards in high reliability and chemical nickel gold process is the adhesive used to prepare the covering film. Therefore, improving the manufacturing technology of the adhesive of the covering film with resistance to chemical gold has become a hot topic in the industry. Especially in 5G and future 6G communication, the excellent resistance to chemical gold and high-frequency performance of the covering film provide a solid foundation for its application in high-frequency circuits. Therefore, it is particularly important to develop a high-frequency covering film resistant to chemical gold and the adhesive used to prepare the same. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide an adhesive and a high-frequency covering film resistant to chemical gold prepared therefrom, which is suitable for manufacturing high-frequency printed circuit board substrates. The preparation method of the adhesive is simple, easy to implement, and suitable for mass production. Moreover, the high-frequency covering film prepared using the adhesive has excellent resistance to chemical gold, can improve the plating penetration phenomenon in the chemical nickel gold process, and also has excellent dielectric properties.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] An adhesive comprises the following components by weight:

[0007]

[0008] The acid value of the polyimide resin in the polyimide resin emulsion is 0.07-0.12 mol / kg.

[0009] Further preferably, the adhesive for high-frequency covering film of the present application is composed of the following components by weight: polyimide resin emulsion with an acid value of 0.10 mol / kg 1000 parts, epoxy resin emulsion 150 parts, silicon powder 160 parts, epoxy curing agent emulsion 32 parts, and BMI curing agent emulsion 40 parts; the acid value of the polyimide resin in the polyimide resin emulsion is 1.0 mol / kg.

[0010] In the present application, the polyimide resin emulsion is mixed from polyimide resin and cyclohexanone; the solid content of the polyimide resin is 20-50 wt%. Preferably, the polyimide resin is selected from the polyimide resin with the brand SP1T04L produced by Yinshi Science and Technology.

[0011] In the present application, the epoxy resin emulsion is mixed from epoxy resin and butanone; the solid content of the epoxy resin is 50-100 wt%. Preferably, the epoxy resin of the present application is selected from the epoxy resin with the brand XD-1000 produced by Japan Chemical Medicine.

[0012] In the present application, the particle size of the silicon powder is 2-5 um. Preferably, the silicon powder of the present application is selected from the silicon powder with the brand Q029 produced by Jin Yi.

[0013] In the present application, the epoxy curing agent emulsion is a polyol amine type epoxy curing agent emulsion, which is mixed from epoxy curing agent and butanone; the solid content of the epoxy curing agent is 40-60 wt%. Preferably, the epoxy curing agent of the present application is selected from the epoxy curing agent with the brand JER630 produced by Mitsubishi Chemical.

[0014] In the present application, the BMI (diphenyl methane bismaleimide) curing agent emulsion is mixed from BMI curing agent and butanone; the solid content of the BMI curing agent is 30-50 wt%. Preferably, the BMI curing agent of the present application is selected from the BMI curing agent with the brand UMI-0 produced by You Niji Ke.

[0015] The present application further provides a preparation method of the adhesive, which is specifically as follows: after mixing the polyimide resin emulsion, the epoxy resin emulsion, the silicon powder, the epoxy curing agent emulsion, and the BMI curing agent emulsion uniformly, stirring uniformly at 20-35 ℃ for 3-5 hours.

[0016] The application further provides a high-frequency covering film resistant to nickel plating, comprising a film layer and an adhesive layer formed by coating the adhesive prepared by the application on the lower surface of the film layer, and a release layer is bonded below the adhesive layer.

[0017] Further, the film layer in the application is a polyimide layer; the release layer is a release paper; the thickness of the polyimide layer is 8-50 μm, the thickness of the adhesive layer is 8-50 μm, and the thickness of the release layer is 110-150 μm.

[0018] The material of the polyimide layer is polyimide, which is a kind of polymer containing imide ring (-CO-N-CO-) in the main chain, has a high-temperature resistance of up to 400℃ or above, a long-term use temperature range of -200-300℃, and high insulation performance.

[0019] The application has the following beneficial effects:

[0020] The preparation method of the adhesive is simple, easy to implement, and suitable for mass production, and the adhesive can be used to prepare the high-frequency covering film resistant to nickel plating, and the prepared covering film has excellent nickel plating resistance, can improve the penetration plating phenomenon in the nickel plating process, has excellent dielectric properties, i.e., low dielectric constant (Dk) and dielectric loss tangent (Df), and can maintain its stability when the environmental conditions such as temperature, frequency, and humidity change, has a characteristic impedance with high-precision control, has low water absorption and good mechanical processing performance and dimensional stability, the copper foil peel strength (1 / 2OZ) is greater than 1.0 N / mm, the flame retardance reaches UL94V-0 level, and the excellent comprehensive performance completely meets the production requirements of millimeter wave radar substrates. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 FIG. 1 is a structural schematic diagram of the high-frequency covering film resistant to nickel plating prepared by the adhesive of the application. DETAILED DESCRIPTION

[0022] The application will be further described below in combination with specific embodiments, but is not limited thereto.

[0023] The adhesive provided in the specific embodiments of the application comprises the following components by weight:

[0024]

[0025] In the polyimide resin emulsion, the acid value of the polyimide resin is 0.07-0.12 mol / kg. In the specific embodiments, a dispersant can be appropriately added to improve the stability of the emulsion.

[0026] The polyimide resin emulsion is mixed with cyclohexanone at a solid content of 20-50 wt%; the epoxy resin emulsion is mixed with butanone at a solid content of 50-100 wt%; the epoxy curing agent emulsion is a polyol amine type epoxy curing agent emulsion, mixed with butanone at a solid content of 40-60 wt%; the BMI curing agent emulsion is mixed with butanone at a solid content of 30-50 wt%; and the silicon micropowder has a particle size of 2-5 um.

[0027] The polyimide resin is SP1T04L produced by Silver Peak Technology; the epoxy resin is XD-1000 produced by Japan Chemical; the epoxy curing agent is JER630 produced by Mitsubishi Chemical; the BMI curing agent is UMI-0 produced by You Niji Ke; and the silicon micropowder is Q029 produced by Jin Yi.

[0028] The embodiment also provides a preparation method of the adhesive, and the preparation method specifically includes the following steps:

[0029] The polyimide resin emulsion, the epoxy resin emulsion, the silicon micropowder, the epoxy curing agent emulsion and the BMI curing agent emulsion are uniformly mixed, and then stirred at 20-35 °C for 3-5 hours.

[0030] Embodiment

[0031] Embodiment 1

[0032] The adhesive for the high-frequency covering film containing resistant gold according to the embodiment includes, by weight, 1000 parts of polyimide resin emulsion with an acid value of 0.07 mol / kg, 150 parts of epoxy resin emulsion, 160 parts of silicon micropowder, 32 parts of epoxy curing agent emulsion and 40 parts of BMI curing agent emulsion; and the acid value of the polyimide resin in the polyimide resin emulsion is 0.7 mol / kg.

[0033] The polyimide resin emulsion is mixed with cyclohexanone at a solid content of 35 wt%; the epoxy resin emulsion is mixed with butanone at a solid content of 75 wt%; the epoxy curing agent emulsion is a polyol amine type epoxy curing agent emulsion, mixed with butanone at a solid content of 50 wt%; the BMI curing agent emulsion is mixed with butanone at a solid content of 40 wt%; and the silicon micropowder has a particle size of 2-5 um.

[0034] The polyimide resin is selected from the polyimide resin with the brand of SP1T04L produced by Silver Peak Technology; the epoxy resin is selected from the epoxy resin with the brand of XD-1000 produced by Japan Chemical; the epoxy curing agent is selected from the epoxy curing agent with the brand of JER630 produced by Mitsubishi Chemical; the BMI curing agent is selected from the BMI curing agent with the brand of UMI-0 produced by Unijet; and the silicon micro powder is selected from the silicon micro powder with the brand of Q029 produced by Jin Yi.

[0035] Example 2

[0036] The difference between the present example and Example 1 is that the acid value of the polyimide resin in the polyimide resin emulsion in the present example is 1.0 mol / kg; the content of other components and the preparation method are the same as those in Example 1.

[0037] Example 3

[0038] The difference between the present example and Example 1 is that the acid value of the polyimide resin in the polyimide resin emulsion in the present example is 1.2 mol / kg; the content of other components and the preparation method are the same as those in Example 1.

[0039] Comparative Example

[0040] Comparative Example 1

[0041] The difference between the present example and Example 1 is that the acid value of the polyimide resin in the polyimide resin emulsion in the present example is 0.6 mol / kg; the content of other components and the preparation method are the same as those in Example 1.

[0042] Comparative Example 2

[0043] The difference between the present example and Example 1 is that the acid value of the polyimide resin in the polyimide resin emulsion in the present example is 1.4 mol / kg; the content of other components and the preparation method are the same as those in Example 1.

[0044] Comparative Example 3

[0045] The present comparative example uses a commercially available conventional high-frequency covering film.

[0046] Application Example

[0047] The adhesives prepared in Examples 1-3 and Comparative Examples 1-3 of the present application are respectively used to make high-frequency covering films resistant to chemical gold, as shown in the following table. Figure 1 As shown in the table, the high-frequency covering film resistant to chemical gold includes a film layer 1 and an adhesive layer 2 formed by coating the adhesive produced by Examples 1-3 and Comparative Examples 1-3 of the present application on the lower surface of the film layer 1, and a release layer 3 is bonded below the adhesive layer 2. And they are respectively and correspondingly marked as Application Examples 1-3 and Application Comparative Examples 1-3.

[0048] The film layer 1 is a polyimide (PI) layer produced by SKC; the release layer 3 is a release paper; the thickness of the polyimide layer is 25 μm, the thickness of the adhesive layer is 25 μm, and the thickness of the release layer is 130 μm.

[0049] Performance evaluation

[0050] The gold resistance high-frequency cover films made of the adhesives of Examples 1-3 and Comparative Examples 1-3 are tested for performance, including the surface morphology of the adhesive film, heat resistance, gold plating, peel strength, and dimensional stability.

[0051] 1. Surface morphology of the adhesive film: observed by naked eyes and recorded, and the results are shown in Table 1.

[0052] 2. The peel strength, tensile strength, elongation, modulus, heat resistance, dielectric constant, dielectric loss factor, and dimensional stability are tested according to the test methods specified in IPC-TM-650, JIS C6471, and the results are shown in Table 1.

[0053] Table 1: Performance test results

[0054]

[0055]

[0056] From the above performance test table, it can be seen that, in the present application, the gold resistance performance of Comparative Example 1 is poorer than that of Examples 1-3, that is, when the component contents are the same, too low acid value of the polyimide resin will affect the gold resistance performance of the gold resistance high-frequency cover film; the dielectric performance of Comparative Example 2 is poorer than that of Examples 1-3, that is, when the component contents are the same, too high acid value of the polyimide resin will affect the dielectric performance of the gold resistance high-frequency cover film (the dielectric loss factor increases significantly); according to Comparative Example 3, the gold resistance performance of the conventional high-frequency cover film commonly used in the market is poor and cannot meet the application requirements.

[0057] In summary, the gold resistance high-frequency cover film prepared using the adhesive of the present application can meet the requirements of IPC-4203B standard, has excellent heat resistance, and can meet the application requirements of FPCB in the field of high heat resistance and high reliability, and has good prospects for industrial production and broad application prospects.

Claims

1. An adhesive, characterized in that The composition comprises the following components in parts by weight: The acid value of the polyimide resin in the polyimide resin emulsion is 0.07 to 0.12 mol / kg.

2. The adhesive for gold-resistant high-frequency covering film according to claim 1, characterized in that The invention is composed of the following components in parts by weight: 1000 parts of a polyimide resin emulsion having an acid value of 0.10 mol / kg, 150 parts of an epoxy resin emulsion, 160 parts of silicon micropowder, 32 parts of an epoxy curing agent emulsion, and 40 parts of a BMI curing agent emulsion; the acid value of the polyimide resin in the polyimide resin emulsion is 1.0 mol / kg.

3. The adhesive for gold-resistant high-frequency covering film according to claim 1, characterized in that The polyimide resin emulsion is prepared by mixing polyimide resin and cyclohexanone; wherein the solid content of the polyimide resin is 20-50wt%.

4. The adhesive for gold-resistant high-frequency covering film according to claim 1, characterized in that The epoxy resin emulsion is prepared by mixing epoxy resin and butanone; wherein the solid content of the epoxy resin is 50-100 wt%.

5. The adhesive for gold-resistant high-frequency covering film according to claim 1, characterized in that The particle size of the silicon micropowder is 2 to 5 μm.

6. The adhesive for gold-resistant high-frequency covering film according to claim 1, characterized in that The epoxy curing agent emulsion is a polyolamine type epoxy curing agent emulsion, and the epoxy curing agent emulsion is formed by mixing an epoxy curing agent and butanone; wherein the solid content of the epoxy curing agent is 40 to 60 wt%.

7. The adhesive for gold-resistant high-frequency covering film according to claim 1, characterized in that The BMI curing agent emulsion is prepared by mixing BMI curing agent and butanone; wherein the solid content of the BMI curing agent is 30 to 50 wt%.

8. A method for preparing an adhesive according to any one of claims 1 to 7, characterized in that The preparation method comprises the following steps: uniformly mixing polyimide resin emulsion, epoxy resin emulsion, silicon micropowder, epoxy curing agent emulsion and BMI curing agent emulsion, and stirring the mixture uniformly at 20-35° C. for 3-5 hours.

9. A high-frequency gold-resistant covering film, characterized in that The adhesive layer comprises a film layer (1) and an adhesive layer (2) formed by coating the adhesive prepared in claim 8 on the lower surface of the film layer (1), wherein a release layer (3) is bonded below the adhesive layer (2).

10. The chemical-resistant gold high-frequency covering film according to claim 9, characterized in that The film layer (1) is a polyimide layer; the release layer (3) is a release paper; the thickness of the polyimide layer is 8 to 50 μm, the thickness of the adhesive layer is 8 to 50 μm, and the thickness of the release layer is 110 to 150 μm.

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