Adhesive for high-Tg cover film as well as preparation method and application of adhesive

Abstract

The invention discloses an adhesive for a high-Tg cover film as well as a preparation method and application of the adhesive. The adhesive for the high-Tg cover film is prepared from the following components in parts by mass: 200 to 800 parts of polyvinyl butyral emulsion, 100 to 130 parts of epoxy resin emulsion, 80 to 100 parts of bisphenol A epoxy resin emulsion, 30 to 80 parts of talcum powder, 1 to 10 parts of ion capturing agent emulsion, 30 to 60 parts of PI resin and 1 to 10 parts of curing agent. The Tg cover film prepared by adopting the adhesive for the high Tg cover film has excellent dielectric properties, can still keep the stability when environmental conditions such as temperature, frequency and humidity are changed, and has high-precision control characteristic impedance and very high glass transition temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to an adhesive for a high Tg covering film and a preparation method and application thereof. Background Art

[0002] Printed circuit boards (PCBs) are important connection and assembly platforms for electronic products and are considered the "mother of electronic system products". Covering films are very important raw materials for printed circuit boards. Insulating base films and adhesives are the main components of covering films. Adhesives are the medium for bonding insulating base film materials and copper foil. The various properties of adhesives can directly determine the overall performance of copper clad boards. At present, the global driverless car industry is developing well. As an important component of driverless driving, the market of millimeter-wave radar is also rapidly expanding with the development of driverless technology. In millimeter-wave radar manufacturing materials, there are higher requirements for the glass transition temperature (Tg) of the covering film, because higher Tg corresponds to higher thermal decomposition temperature. At high Tg and thermal decomposition temperature, the material has a low thermal expansion coefficient, and the stress change in the circuit substrate is small, which is conducive to improving the heat resistance, stability and service life of the PCB board. Therefore, the manufacturing technology of high glass transition temperature (Tg) substrate materials has become a hot spot in the industry. Especially driven by the 5G era, more and more electronic products use high Tg printed circuit boards to meet the integrity and stability of transmission signals.

[0003] At present, the glass transition temperature of epoxy adhesives and acrylic adhesives used in cover films is mostly around 40°C. Flexible printed circuit boards are mainly made of flexible copper clad laminates and cover films. In high reliability and high heat resistance applications, most of them use adhesive-free flexible copper clad laminates, whose glass transition temperature is usually greater than 200°C and have excellent heat resistance and reliability. In this case, the shortcoming that restricts the use of flexible printed circuit boards in high reliability and high heat resistance fields is the cover film. When the operating temperature of the flexible printed circuit board is higher than the glass transition temperature of the cover film, the reliability and flexural resistance of the flexible printed circuit board will drop sharply. Therefore, it is necessary to provide an adhesive that meets the application requirements of high heat resistance and high reliability and is suitable for manufacturing high Tg printed circuit board substrate-high Tg cover film. Summary of the invention

[0004] The purpose of the present invention is to provide an adhesive for a high Tg cover film in view of the deficiencies in the prior art. The Tg cover film prepared by using the adhesive has excellent dielectric properties and can still maintain its stability when environmental conditions such as temperature, frequency, and humidity change. It has a characteristic impedance controlled with high precision and a very high glass transition temperature. The present invention also provides a method for preparing the adhesive.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An adhesive for high Tg covering film, comprising the following components in parts by weight:

[0007]

[0008] Furthermore, the adhesive is composed of the following components in parts by mass: 800 parts of polyvinyl butyral emulsion, 120 parts of epoxy resin emulsion, 100 parts of bisphenol A epoxy resin, 60 parts of talcum powder, 4 parts of ion capture agent, 50 parts of PI resin, and 5 parts of curing agent.

[0009] The solid content of the polyvinyl alcohol butyral emulsion in the present invention is 5-50wt%. The polyvinyl alcohol butyral emulsion is KS5Z produced by Sekisui Chemical.

[0010] The solid content of the epoxy resin emulsion is 5 to 40 wt %;

[0011] The solid content of the bisphenol A epoxy resin emulsion is 50-100wt%;

[0012] The solid content of the ion catcher emulsion is 1 to 20 wt%;

[0013] The solid content of the PI resin is 5 to 50 wt%;

[0014] The solid content of the curing agent is 3-20wt%.

[0015] The epoxy resin emulsion is JER1256 produced by Mitsubishi Chemical; the bisphenol A epoxy resin is GELR128E produced by Hongchang; the ion capture agent is IXE-100 produced by Toagosei Co., Ltd.; the PI resin solution is PIAD200 produced by Arakawa; and the curing agent is JER630.

[0016] The present invention also provides a method for preparing the adhesive for high Tg covering film, the steps of which are as follows: polyvinyl alcohol butyral emulsion, epoxy resin emulsion, bisphenol A epoxy resin, talcum powder, ion catcher, PI resin and curing agent are mixed in proportion, uniformly dispersed in a solvent and stirred evenly.

[0017] The solvent is one of butanone and cyclohexanone. The solid content of the prepared adhesive for high Tg covering film is 25-35wt%.

[0018] In the present invention, the adhesive for high Tg covering film is used to prepare high Tg covering film.

[0019] The high Tg covering film of the present invention comprises an adhesive film and release paper; the adhesive film comprises a film substrate, one side of which is coated with an adhesive layer of an adhesive for high Tg covering film; the release paper is pressed onto the adhesive layer.

[0020] The material of the film substrate is selected from PI (Polyimide), which refers to a type of polymer containing an imide ring (-CO-N-CO-) on the main chain. It has a high temperature resistance of more than 400°C and a long-term use temperature range of -200 to 300°C, and has high insulation performance.

[0021] The preparation method of the high Tg covering film of the present invention can be any method known to those skilled in the art, for example, uniformly coating a single surface of a film substrate with an adhesive for the high Tg covering film, drying the film, and laminating the film with a release paper to obtain the high Tg covering film.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The preparation method of the adhesive for high Tg covering film of the present invention is simple, has strong high temperature resistance, is easy to implement, and is convenient for mass production;

[0024] (2) The high Tg covering film prepared by the adhesive for high Tg covering film of the present invention has excellent dielectric properties and can maintain its stability when the environmental conditions such as temperature, frequency, humidity, etc. change, and has a characteristic impedance controlled with high precision; glass transition temperature Tg>115℃(DSC); Z-axis expansion coefficient CTE<2.85%; heat resistance TD≥340℃, T288>10min; copper foil peel strength (1 / 2OZ)>1.0N / mm;

[0025] (3) The high Tg covering film prepared by the adhesive for high Tg covering film of the present invention has low water absorption, good mechanical processing performance and dimensional stability, and the flame retardancy reaches UL94V-0 level, which can fully meet the production requirements of millimeter wave radar substrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of the high Tg covering film of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to specific embodiments, but is not limited thereto.

[0028] Example

[0029] Example 1

[0030] Example 1 provides an adhesive for a high Tg covering film, which includes, by weight, 800 parts of polyvinyl butyral emulsion, 120 parts of epoxy resin emulsion, 100 parts of bisphenol A epoxy resin, 60 parts of talcum powder, 4 parts of ion capture agent, 50 parts of PI resin, and 5 parts of curing agent.

[0031] The polyvinyl alcohol butyral emulsion is KS5Z produced by Sekisui Chemical; the epoxy resin emulsion is JER1256 produced by Mitsubishi Chemical; the bisphenol A epoxy resin is GELR128E produced by Hongchang; the ion capture agent is IXE-100 produced by Toagosei Co., Ltd.; the PI resin solution is PIAD200 produced by Arakawa; and the curing agent is JER630.

[0032] The preparation method of the adhesive for high Tg covering film in this embodiment comprises the following steps: polyvinyl alcohol butyral emulsion, epoxy resin emulsion, bisphenol A epoxy resin, talcum powder, ion catcher, PI resin and curing agent are mixed in proportion, dispersed and stirred evenly in butanone solvent, and the solid content of the adhesive for high Tg covering film is adjusted to 25wt%.

[0033] This embodiment also provides a high Tg covering film, including an adhesive film 1 and a release paper 2; the adhesive film 1 includes a film substrate 11, a single side of which is coated with an adhesive layer 12 of an adhesive for a high Tg covering film; the release paper 2 is pressed onto the adhesive layer 12.

[0034] The film substrate is a PI film produced by SKC.

[0035] This example also provides a method for preparing the above-mentioned high Tg covering film, comprising the following steps: uniformly coating a layer of adhesive for high Tg covering film on one side of the PI film, and after drying, covering one side of the adhesive film with release paper and pressing it to obtain the high Tg covering film.

[0036] Example 2

[0037] Example 2 provides an adhesive for a high Tg covering film, which includes, by weight, 200 parts of polyvinyl butyral emulsion, 100 parts of epoxy resin emulsion, 90 parts of bisphenol A epoxy resin, 30 parts of talcum powder, 6 parts of ion capture agent, 60 parts of PI resin, and 1 part of curing agent.

[0038] The types of materials used for the components of this embodiment and the preparation method of the adhesive for high Tg covering film are the same as those in Example 1, but the solvent used is cyclohexanone.

[0039] This example also provides a high Tg covering film, which is different from Example 1 in that the film substrate is a PI film produced by Guilin Electric.

[0040] This example also provides a method for preparing the above-mentioned high Tg covering film, which is similar to Example 1.

[0041] Example 3

[0042] Example 3 provides an adhesive for a high Tg covering film, which includes, by weight, 500 parts of polyvinyl butyral emulsion, 115 parts of epoxy resin emulsion, 90 parts of bisphenol A epoxy resin, 80 parts of talcum powder, 6 parts of ion capture agent, 45 parts of PI resin, and 5 parts of curing agent.

[0043] The types of materials used for the components of this embodiment and the preparation method of the adhesive for the high Tg cover film are the same as those in Embodiment 1.

[0044] The difference between this embodiment and embodiment 1 is that the film substrate is a PI film produced by Anhui Tongwei New Materials.

[0045] This example also provides a preparation method of the above-mentioned high Tg, which is the same as Example 1.

[0046] Comparative Example 1

[0047] Comparative Example 1 provides an adhesive, which differs from Example 1 in that the adhesive does not contain polyvinyl butyral. The types of materials used for other components and the preparation method of the adhesive are the same as those in Example 1.

[0048] This example also provides a covering film, which includes an adhesive film 1 and a release paper 2; the adhesive film 1 includes a film substrate 11, one side of which is an adhesive layer 12 coated with the above mixture; the release paper 2 is pressed on the adhesive layer 12 on one side of the adhesive film. The film substrate is a PI film produced by SKC.

[0049] Performance Testing

[0050] The covering films prepared in Examples 1-3 and Comparative Example 1 were subjected to performance tests, and the test contents included the surface morphology, heat resistance, glass transition temperature Tg, peel strength, and dimensional stability of the adhesive film.

[0051] 1. Surface morphology of adhesive film: observe and record with naked eyes. The results are shown in Table 1.

[0052] 2. According to the test methods specified in IPC-TM-650 and JIS C6471, the performance tests such as peel strength, tensile strength, elongation, modulus, heat resistance and dimensional stability were carried out. The results are shown in Table 1.

[0053] Table 1 Performance test results of embodiments and comparative examples

[0054]

[0055] As can be seen from the above table, the physical properties of Examples 1-3 of the present invention are similar; the glass transition temperature Tg of Comparative Example 1 is significantly inferior to that of Example 1, and the heat resistance of Comparative Example 1 is poor and cannot meet the use requirements. By comparing the Examples and Comparative Examples, it can be seen that adding polyvinyl alcohol butyral emulsion to the adhesive for high Tg covering film can increase the glass transition temperature Tg, and the heat resistance is significantly improved.

[0056] The high Tg covering film prepared by using the adhesive for high Tg covering film of the present invention can meet the requirements of IPC-4203B standard, and has excellent heat resistance, can meet the application requirements of FPCB in the field of high heat resistance and high reliability, and has good industrial production prospects and broad application prospects.

Claims

1. An adhesive for high Tg cover film, characterized in that It is composed of the following components in percentage by mass:

2. The high Tg cover film adhesive according to claim 1, characterized in that The solid content of the polyvinyl alcohol butyral emulsion is 5 to 50 wt %.

3. The high Tg cover film adhesive according to claim 2, characterized in that The polyvinyl alcohol butyral emulsion is KS5Z produced by Sekisui Chemical.

4. The high Tg cover film adhesive according to claim 1, characterized in that The solid content of the epoxy resin emulsion is 5-40wt%; the solid content of the bisphenol A epoxy resin emulsion is 50-100wt%; the solid content of the ion catcher emulsion is 1-20wt%; the solid content of the PI resin is 5-50wt%; the solid content of the curing agent is 3-20wt%.

5. The high Tg cover film adhesive according to claim 4, characterized in that The epoxy resin emulsion is JER1256 produced by Mitsubishi Chemical; the bisphenol A epoxy resin is GELR128E produced by Hongchang; the ion capture agent is IXE-100 produced by Toagosei Co., Ltd.; the PI resin solution is PIAD200 produced by Arakawa; and the curing agent is JER630.

6. A method for preparing the adhesive for high Tg cover film according to any one of claims 1 to 5, characterized in that The steps are as follows: polyvinyl alcohol butyral emulsion, epoxy resin emulsion, bisphenol A epoxy resin, talcum powder, ion capture agent, PI resin and curing agent are mixed in proportion, uniformly dispersed in the solvent and stirred evenly.

7. The method for preparing the adhesive for high Tg cover film according to claim 6, characterized in that The solvent is one of butanone and cyclohexanone.

8. The method for preparing the adhesive for high Tg cover film according to claim 6, characterized in that The solid content of the prepared adhesive for high Tg covering film is 25-35 wt %.

9. An application of the high Tg cover film adhesive according to any one of claims 1 to 5, characterized in that The high Tg cover film adhesive is used for making a high Tg cover film.

10. Use of the high Tg cover film adhesive according to claim 9 in a cover film, characterized in that The high Tg covering film comprises an adhesive film (1) and a release paper (2); the adhesive film (1) comprises a film substrate (11), one side of which is coated with an adhesive layer (12) of an adhesive for the high Tg covering film; the release paper (2) is pressed onto the adhesive layer (12).

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