CN114940816A

CN114940816A - Cross-linkable polyphenyl ether film and preparation method and application thereof

Info

Publication number: CN114940816A
Application number: CN202210751699.XA
Authority: CN
Inventors: 安丽华; 陈曙光
Original assignee: Shanghai Zaizheng Chemical Technology Development Co ltd
Current assignee: Shanghai Zaizheng Chemical Technology Development Co ltd
Priority date: 2022-06-28
Filing date: 2022-06-28
Publication date: 2022-08-26

Abstract

The present application discloses a crosslinkable polyphenylene ether film and a preparation method and application thereof, including the following steps: step 1) dissolving raw materials containing crosslinkable polyphenylene ether resin, thermoplastic elastomer, crosslinking agent and initiator in a solvent to obtain a raw material solution; step 2) heating the raw material solution to evaporate the solvent to dryness, and subjecting the cross-linkable polyphenylene ether resin to a cross-linking polymerization reaction to obtain a cross-linked polyphenylene ether film. Since the cross-linkable polyphenylene ether contains vinyl structural units, in the process of preparing printed circuit boards, after a high-temperature lamination process, chemical cross-linking can be carried out to obtain a thermosetting polyphenylene ether film with heat resistance and solvent resistance. improve.

Description

Cross-linkable polyphenyl ether film and preparation method and application thereof

Technical Field

The invention belongs to the field of flexible circuit boards, and particularly relates to a crosslinkable polyphenyl ether film and a preparation method and application thereof.

Background

A Flexible Printed Circuit Board (hereinafter referred to as a "Flexible Printed Circuit Board") is called a "Flexible Printed Circuit Board" for short, and is commonly referred to as an FPC in the industry, and is a Printed Circuit Board made of a Flexible insulating base material, and has many advantages that a rigid Printed Circuit Board does not have. For example, it can be freely bent, rolled, folded. The FPC can be used for greatly reducing the volume of electronic products, and is suitable for the development of the electronic products in the directions of high density, miniaturization and high reliability. Therefore, the FPC is widely applied to the fields or products of aerospace, military, mobile communication, portable computers, computer peripherals, PDAs, digital cameras and the like.

With the revolution of modern information technology, digital circuits gradually step into the stages of high speed information processing and high frequency signal transmission, and the frequency of electronic devices is becoming higher and higher in order to process ever increasing data. Therefore, on the basis of meeting the traditional design and manufacturing requirements, the performance of the microwave dielectric circuit substrate material is required to be updated. Since the signals applied to the printed circuit board must use high frequency, how to reduce the transmission loss and signal delay on the circuit board becomes a difficult problem in designing and manufacturing the high frequency circuit.

The dielectric material currently used for high-frequency flexible circuit boards is a polyarylate film (LCP) having thermotropic liquid crystal characteristics, and the LCP material has the characteristics of low dielectric constant (Dk ═ 2.9) and low dielectric loss (Df ═ 0.001 to 0.002), and is more suitable for high-frequency signal transmission. Because LCP molecules have liquid crystal characteristics in a molten state, the LCP molecules are easy to break under force in the TD direction after being subjected to melt processing and film forming. Superex (Foster-Miller) was first introduced for LCP film production and development, where the molecular alignment was controlled by rotating the die to control the shear stress in different directions. The daily business is to further control the film characteristics in MD/TD direction through the inflation process in the film blowing process. Primatec refers to the improvement of the molecular alignment property in the TD direction by biaxial stretching secondary processing. However, the above melt processing methods cannot obtain isotropic films, and thus, the application of the method in the printed circuit board industry and other industries is limited.

Polyphenylene Oxide (PPO) (usually the number average molecular weight is 18000-24000) is an important engineering plastic, is nontoxic, transparent, has small relative density, and has excellent mechanical strength, stress relaxation resistance, creep resistance, heat resistance, water vapor resistance and dimensional stability. The dielectric constant and dielectric loss of the PPO plastic raw material are one of the smallest varieties in engineering plastics, are hardly influenced by temperature and humidity, and can be used in the fields of low, medium and high-frequency electric fields. However, PPO has poor resistance to aromatic hydrocarbons, halogenated hydrocarbons, oils, etc., and is liable to swelling or stress cracking. In addition, the glass transition temperature of PPO is 211 ℃, the melting point is 268 ℃, so that the copper-clad plate made of the PPO film cannot pass the 288 ℃ tin-floating test. These all limit the application of PPO film in flexible circuit board industry.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention is directed to a cross-linkable PPO film, a printed circuit board substrate made of the same and a method for manufacturing the same, which are used to solve the above-mentioned problems in the prior art.

A preparation method of a crosslinkable polyphenyl ether film comprises the following steps:

step 1) dissolving raw materials containing a crosslinkable polyphenyl ether resin, a thermoplastic elastomer, a crosslinking agent and an initiator in a solvent to obtain a raw material solution;

and 2) heating the raw material solution to evaporate the solvent, and performing crosslinking polymerization reaction on the crosslinkable polyphenyl ether resin to obtain the crosslinkable polyphenyl ether film.

Optionally, the crosslinkable polyphenylene ether resin in step 1) has a chemical formula shown in formula I:

wherein X is at least one of the following organic groups;

the R1 and R2 are the following groups containing a vinyl functionality:

m is more than or equal to 1 and less than or equal to 158, n is more than or equal to 1 and less than or equal to 158, and m + n is more than or equal to 16 and less than or equal to 160.

Optionally, the crosslinkable polyphenylene ether resin has a number average molecular weight of 2000g/mol to 20000 g/mol.

Optionally, the crosslinkable polyphenylene ether resin has a number average molecular weight of from 5000g/mol to 18000 g/mol.

Optionally, the crosslinkable polyphenylene ether resin is a substance represented by formula II:

wherein, X is:

optionally, the raw materials comprise the following components in percentage by mass:

70-90 percent of cross-linked polyphenyl ether resin

5 to 25 percent of thermoplastic elastomer

1 to 5 percent of cross-linking agent

1 to 3 percent of initiator.

Optionally, the thermoplastic elastomer is a block copolymer of styrene.

Optionally, the thermoplastic elastomer comprises at least one of SBS (styrene-butadiene-styrene), SIS (styrene-isoprene-styrene), SIBS (styrene-isoprene/butadiene-styrene), SEBS (styrene-ethylene/butylene-styrene) and SEPS (styrene-ethylene/propylene-styrene).

Optionally, the thermoplastic elastomer is styrene-ethylene/butylene-styrene;

optionally, the crosslinking agent is at least one of trimethyolprooyl isocyanate (TMAIC), triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), and trimethylolpropane acrylate (TMPTA).

Optionally, the initiator is an organic peroxy initiator.

Optionally, the organic peroxy initiator comprises at least one of dialkyl peroxides, hydroperoxides, peroxyesters, diacyl peroxides, and peroxydicarbonates.

Optionally, the dialkyl peroxide comprises di-tert-butyl peroxide, dicumyl peroxide.

Optionally, the hydroperoxide comprises cumene hydroperoxide, tert-butyl hydroperoxide.

Optionally, the initiator is dicumyl peroxide and/or di- (tert-butylperoxyisopropyl) benzene.

Optionally, the solvent comprises at least one of benzene, toluene, chloroform, and tetrahydrofuran.

Optionally, in the step 2), the raw material solution is coated on the surface of the base material in a casting manner, and then the solvent is heated and evaporated to dryness; and then heating at 170-250 deg.C for 1 hr or more, preferably 1-2 hr, to crosslink and polymerize the crosslinkable polyphenylene ether resin to obtain the crosslinkable polyphenylene ether film.

Optionally, the mass fraction of the solvent in the raw material solution is 30% -80%.

As another aspect of the present application, the present application also provides a crosslinkable polyphenylene ether film prepared by the above method.

Alternatively, the cross-linkable polyphenylene ether film has a thickness of 10 to 150 μm.

Alternatively, the cross-linkable polyphenylene ether film has a thickness of 12.5 to 100 μm.

As a specific embodiment of the above production method: the cross-linkable PPO, the thermoplastic elastomer, the cross-linking agent assistant and the free radical initiator are mixed according to a certain proportion and then dissolved in an organic solvent, such as benzene, toluene, chloroform, tetrahydrofuran and the like, at a certain concentration, and the solvents can be used singly or in combination. And uniformly coating the solution on the surface of a flat substrate or a strip-shaped substrate in a casting manner, and after drying the solvent, stripping the obtained film from the surface of the substrate.

The amount of the solvent used is appropriate, and if the concentration of the solution is too low, the viscosity is too low to allow uniform coating on the surface of the substrate, and the cost is high from the economical viewpoint. On the other hand, if the concentration is too high, the viscosity is too high, and the coating cannot be uniformly applied to the surface of the substrate.

The substrate can be glass, ceramic and metal materials, and can also be heat-resistant and solvent-resistant engineering plastics, such as polytetrafluoroethylene. Preferably a metal material, more preferably a stainless steel material, such as a stainless steel foil with a smooth surface.

Examples of the method of the casting coating include a smooth roll coating method, a gravure roll coating method, a blade coating method, an air knife coating method, a dip coating method, a spray coating method, a curtain coating method, a screen printing method, and a slit coating method, and the slit coating method is preferable, and the film is uniform and easy to control.

The thickness of the polyphenylene ether film is 10 to 150 μm, preferably 12.5 to 100 μm. Too thin a film is not easily peeled off from the substrate, and too thick a film requires multiple coating.

Preferably, the solution is uniformly cast and coated on the surface of a flat substrate or a strip-shaped substrate, after drying the solvent, the solution is continuously heated to 170-250 ℃ and kept for more than 1 hour, preferably 1-2 hours, and then the polyphenyl ether film is peeled from the surface of the substrate. Under the high temperature condition, the polyphenylene ether resin generates a crosslinking reaction to obtain a thermosetting polyphenylene ether film, and the heat resistance and the solvent resistance are improved.

As yet another aspect of the present application, there is also provided a polyphenylene ether copper clad film comprising a crosslinkable polyphenylene ether film having a copper foil coated on at least one surface thereof; the cross-linkable polyphenylene oxide film is any one of the cross-linkable polyphenylene oxide films.

As another aspect of the present application, the present application also provides a method for preparing a polyphenylene ether copper-clad film, comprising the steps of: step a) dissolving raw materials containing a crosslinkable polyphenyl ether resin, a thermoplastic elastomer, a crosslinking agent and an initiator in a solvent to obtain a raw material solution;

step b) coating the raw material solution on a copper foil, heating to evaporate the solvent, and performing crosslinking polymerization reaction on the crosslinkable polyphenyl ether resin to obtain a polyphenyl ether copper-clad foil film with a single surface coated with copper;

preferably, the preparation method of the polyphenylene oxide copper foil-coated film further comprises the following steps:

and c) covering a copper foil on the copper-free surface of the single-sided copper-clad polyphenyl ether copper-clad foil film, and heating and pressing to obtain the double-sided copper-clad polyphenyl ether copper-clad foil film.

The following is a specific embodiment of the above preparation method:

one, polyphenyl ether copper foil film with single surface copper foil

The cross-linkable PPO, the thermoplastic elastomer, the cross-linking agent assistant and the free radical initiator are mixed according to a certain proportion and then dissolved in an organic solvent, such as benzene, toluene, chloroform, tetrahydrofuran and the like, at a certain concentration, and the solvents can be used singly or in combination. And uniformly coating the solution on the surface of a copper foil in a tape casting manner, and drying the solvent to obtain the polyphenyl ether film with one side covered with the copper foil, wherein the polyphenyl ether film can be used as a flexible circuit board substrate.

The solvent is used in an appropriate amount, and if the solution concentration is too low, the viscosity is too low to allow uniform coating on the surface of the substrate, and the cost is high from the economical point of view. On the other hand, if the concentration is too high, the viscosity is too high, and the coating cannot be uniformly applied to the surface of the substrate.

The copper foil can be a single-sided roughened copper foil or a double-sided roughened copper foil, and preferably, the solution is uniformly coated on the roughened surface of the copper foil in a casting manner.

The copper foil includes a rolled copper foil and an electrolytic copper foil according to a manufacturing method.

The copper foil has a thickness of 8 to 70 μm, preferably 8 μm, 12 μm, 35 μm and 70 μm.

The thickness of the polyphenylene ether film is 10 to 100. mu.m, preferably, 12.5. mu.m, 25. mu.m, 50. mu.m, 75. mu.m and 100. mu.m.

Two-sided copper foil-coated polyphenyl ether film base material

And taking the single-sided copper clad polyphenyl ether film substrate and one copper foil, oppositely laminating the polyphenyl ether film surface and the other copper foil together, and performing high-temperature lamination by using a flat vulcanizing machine to obtain the polyphenyl ether film with the double sides covered with the copper foils, wherein the polyphenyl ether film can be used as a flexible circuit board substrate.

Preferably, the high-temperature pressing temperature is more than 180 ℃, the vinyl in the polyphenyl ether is subjected to a crosslinking reaction to obtain a thermosetting polyphenyl ether film, and the heat resistance and the solvent resistance are improved.

The polyphenyl ether copper-clad film and the polyphenyl ether film can be used as substrates for the flexible circuit board industry, wherein the polyphenyl ether film can be used as a prepreg, and can be used for preparing a single-sided printed circuit board, a double-sided printed circuit board and a multilayer printed circuit board.

Preferably, the polyphenyl ether contains vinyl structural units, and chemical crosslinking can be performed through a high-temperature laminating process at the temperature of more than 180 ℃ in the process of preparing the printed circuit board, so that a thermosetting polyphenyl ether film is obtained, and the heat resistance and the solvent resistance are improved.

The invention also provides a preparation device for preparing the crosslinkable polyphenyl ether film or the polyphenyl ether copper-clad film, which comprises the following steps: the device comprises a base material foil strip, a base material foil strip and a coating layer, wherein a slit die head is arranged above the base material foil strip and is used for coating a raw material solution on the base material foil strip;

and (3) the foil tape coated with the raw material solution passes through a tunnel type oven, and the raw material solution is evaporated to dryness in the tunnel type oven and reacts to form the crosslinkable polyphenyl ether film.

Optionally, the preparation device further comprises a film separation device, and the film separation device separates the crosslinkable polyphenylene ether film from the base material foil tape.

Optionally, the film separating device comprises a film winding mechanism and a substrate foil tape winding mechanism.

Optionally, the substrate foil is a stainless steel foil.

Optionally, the base material foil is a copper foil, and the raw material solution is evaporated to dryness in a tunnel oven and reacts to form a polyphenylene ether copper foil-clad film with a single surface coated with copper.

Optionally, the preparation device further comprises a polyphenylene oxide copper clad laminate winding mechanism.

The invention has the following beneficial effects:

because the polyphenyl ether contains vinyl structural units, chemical crosslinking can be carried out through a high-temperature pressing process in the process of preparing the printed circuit board to obtain a thermosetting polyphenyl ether film, and the heat resistance and the solvent resistance are improved.

Drawings

FIG. 1 is a schematic view of an apparatus for preparing a crosslinkable polyphenylene ether film;

FIG. 2 is a schematic diagram of a single-sided copper-clad cross-linkable polyphenylene ether film production apparatus.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

Please refer to the attached drawings. It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any structural modification, ratio relationship change, or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are used for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms may be changed or adjusted without substantial change in the technical content.

Examples 1 to 5

1. Preparation of polyphenylene oxide solution

In examples 1 to 5, the polyphenylene ether solutions were prepared as shown in Table 1 with the components and materials shown in Table 2:

table 1 units: parts (quality)

	Cross-linkable PPO	Thermoplastic elastomer	Crosslinking agent aid	Free radical initiators	Solvent (toluene)
						Example 1	70	25	4	1	200
Example 2	75	18	5	2	400
						Example 3	90	5	4	1	200
Example 4	80	17	1	3	200
						Example 5	85	11	2	2	42.86

TABLE 2

*: the cross-linkable PPO has the following structure:

the preparation method of the polyphenylene ether solution of the embodiment comprises the following steps:

the solvent was added to a three-neck flask equipped with mechanical stirring, then the components were added sequentially under stirring according to the formulation of table 1, and stirring was continued for 30 minutes.

Preparation example of polyphenylene ether film:

the polyphenylene ether solutions obtained in examples 1 to 5 were taken and prepared by using an apparatus shown in FIG. 1, the apparatus comprising: the device comprises a stainless steel base material foil strip 2, wherein a slit die head 1 is arranged above the stainless steel base material foil strip 2, and a raw material solution 3 is uniformly coated on the stainless steel foil strip with a bright surface through the slit die head;

the foil tape coated with the raw material solution passes through a tunnel oven 4, and the raw material solution is evaporated to dryness in the tunnel oven at 150 ℃ and reacts to form the crosslinkable polyphenylene oxide film. Then a film winding mechanism and a base material foil strip winding mechanism of the film separating device separate the cross-linked polyphenyl ether film 3 from the stainless steel foil strip 2 to obtain a polyphenyl ether film with the thickness of 25 mu m.

Then, the films obtained above were all placed in an oven at 180 ℃ for 60 minutes, taken out for cooling, and then soaked in an organic solvent and left to stand for 24 hours, with the results shown in table 3 below.

Table 3 film solubility comparative table

NMP

DMAc

DMF

Toluene

Xylene

Chloroform

THF

Example 1

—

Example 2

—

Example 3

—

Example 4

—

Example 5

—

Comparative example

+

+-

+

Note: + means completely soluble (forming a clear solution)

+ -represents partially soluble (film swelling rupture)

Indicating insolubility (intact film profile)

Comparative example is a conventional PPO film (NORYL) ^TM PPE 640 extrusion film)

The crosslinkable polyphenylene ether films of the above examples 1 to 5 can be directly used as prepregs in the printed wiring board industry.

Preparation example of a single-sided copper foil-clad polyphenylene ether film substrate:

taking the crosslinkable polyphenyl ether solution obtained in the embodiment 1-5, as shown in figure 2, uniformly coating the solution on an electrolytic copper foil strip 5 with the thickness of 18um through a slit die head 1 by using a slit coating method, drying the solvent at 150 ℃ through a tunnel furnace 4, and reacting to obtain a polyphenyl ether film copper-clad plate 6 with the copper thickness of 18um and the resin thickness of 25um, wherein the polyphenyl ether film copper-clad plate 6 can be used as a flexible circuit board base material.

Preparation example of double-sided copper foil-clad polyphenylene ether film substrate:

taking the single-side copper foil-coated polyphenyl ether film base material prepared in the embodiment 1-5, cutting a piece with the length of 400mm and the width of 300mm, taking another piece of electrolytic copper foil with the thickness of 18 mu m, oppositely laminating the polyphenyl ether film surface and the other piece of copper foil together, and carrying out high-temperature lamination for 60 minutes by using a flat vulcanizing machine at the lamination temperature of 300 ℃ and the lamination pressure of 4Mpa to obtain the polyphenyl ether film with the double sides coated with the copper foils, wherein the polyphenyl ether film base material can be used as a flexible circuit board base material. The double-sided copper clad polyphenylene oxide film substrate is subjected to a tin floating test, and the results are shown in the following table 4:

TABLE 4 tin bleaching test comparison

Note: comparative example is a conventional PPO film (NORYL) ^TM PPE 640 extruded film)

In conclusion, the present invention effectively overcomes various disadvantages of the prior art and has high industrial utilization value.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims

1. A method for preparing a crosslinkable polyphenylene ether film, comprising the steps of:

and step 2) heating the raw material solution, evaporating the solvent to dryness, and performing crosslinking polymerization reaction on the crosslinkable polyphenyl ether resin to obtain the crosslinkable polyphenyl ether film.

2. The method of claim 1, wherein in step 1), the crosslinkable polyphenylene ether resin has a chemical formula shown in formula I:

wherein X is at least one of the following organic groups;

r1 and R2 are the following groups containing a vinyl functionality:

m is more than or equal to 1 and less than or equal to 158, n is more than or equal to 1 and less than or equal to 158, and m + n is more than or equal to 16 and less than or equal to 160;

preferably, the crosslinkable polyphenylene ether resin has a number average molecular weight of 2000g/mol to 20000 g/mol;

preferably, the crosslinkable polyphenylene ether resin has a number average molecular weight of from 5000g/mol to 18000 g/mol.

3. The process according to claim 1, wherein the crosslinkable polyphenylene ether resin is a substance represented by the formula II and/or a substance represented by the formula III

Wherein, X is:

4. the preparation method according to claim 1, wherein the raw materials comprise the following components in parts by mass:

70-90 percent of cross-linked polyphenyl ether resin

5 to 25 percent of thermoplastic elastomer

1 to 5 percent of cross-linking agent

1 to 3 percent of free radical initiator.

5. The production method according to claim 1, wherein the thermoplastic elastomer is a block copolymer of styrene;

preferably, the thermoplastic elastomer comprises at least one of styrene-butadiene-styrene, styrene-isoprene/butadiene-styrene, styrene-ethylene/butylene-styrene, styrene-ethylene/propylene-styrene;

preferably, the thermoplastic elastomer is styrene-ethylene/butylene-styrene;

preferably, the crosslinking agent is at least one of trimethyolprooyl isocyanate, triallyl isocyanurate, triallyl cyanurate and trimethylolpropane acrylate;

preferably, the initiator is an organic peroxy initiator;

preferably, the initiator is dicumyl peroxide and/or di- (tert-butylperoxyisopropyl) benzene;

preferably, the solvent comprises at least one of benzene, toluene, chloroform, tetrahydrofuran.

6. The preparation method according to claim 1, wherein in the step 2), the raw material solution is coated on the surface of the substrate by casting, and then is heated to evaporate the solvent; and then continuously heating at the temperature of between 170 and 250 ℃ below zero for 1 to 2 hours, and carrying out crosslinking polymerization reaction on the crosslinkable polyphenyl ether resin to obtain the crosslinkable polyphenyl ether film.

7. A crosslinkable polyphenylene ether film obtained by the process according to any one of claims 1 to 6;

preferably, the thickness of the cross-linkable polyphenylene ether film is 10 to 150 μm;

preferably, the crosslinkable polyphenylene ether film has a thickness of 12.5 to 100. mu.m.

8. The polyphenyl ether copper clad film is characterized by comprising a cross-linkable polyphenyl ether film, wherein at least one surface of the cross-linkable polyphenyl ether film is coated with a copper foil;

the crosslinkable polyphenylene ether film is the crosslinkable polyphenylene ether film according to claim 7.

9. The method for preparing a polyphenylene ether copper clad film according to claim 8, comprising the steps of: step a) dissolving raw materials containing a crosslinkable polyphenyl ether resin, a thermoplastic elastomer, a crosslinking agent and an initiator in a solvent to obtain a raw material solution;

preferably, the preparation method of the polyphenylene oxide copper-clad foil film further comprises the following steps:

10. Use of the cross-linkable polyphenylene ether film according to claim 7 or the polyphenylene ether copper-clad film according to claim 8 as a material for a flexible wiring board.