CN116512496A

CN116512496A - Preparation method of prepreg and prepreg

Info

Publication number: CN116512496A
Application number: CN202310390666.1A
Authority: CN
Inventors: 周江; 刘腾; 王钦; 虞成城
Original assignee: Shenzhen Sunway Communication Co Ltd
Current assignee: Shenzhen Sunway Communication Co Ltd
Priority date: 2023-04-04
Filing date: 2023-04-04
Publication date: 2023-08-01

Abstract

The embodiment of the invention relates to the technical field of integrated circuit boards, in particular to a preparation method of a prepreg and the prepreg. Compared with the prior art, the embodiment of the invention adopts the liquid crystal high molecular polymer as a resin substitute, has better flame retardance compared with other thermoplastic resins (such as PP, PET, PC and the like), and has the characteristics of high heat resistance and low dielectric loss because the glass fiber cloth is used as a skeleton to support in LCP, and the dielectric property of the compounded prepreg is not obviously reduced by compounding the glass fiber cloth with the LCP resin.

Description

Preparation method of prepreg and prepreg

Technical Field

The embodiment of the invention relates to the technical field of integrated circuit boards, in particular to a preparation method of a prepreg and the prepreg.

Background

The cured sheet is a raw material for producing and preparing copper-clad plates and PCB (printed circuit board) multilayer boards, and most prepregs at present mainly take common thermosetting resin as a matrix, for example: epoxy resin, cyanate ester, bismaleimide resin, benzoxazine and the like are matched with a sizing machine to be subjected to gum dipping and drying to prepare the adhesive.

Compared with the traditional gum dipping production process, the thermoplastic prepreg production process has no gum mixing process, and reduces the pollution to the environment caused by volatilization of organic solvents and additives.

In carrying out the prior art, the applicant has found that at least the following problems exist in the prior art: in the application fields of high-end PCB boards such as HDI (high density interconnection), IC (integrated circuit) carrier boards and similar carrier boards, copper-clad plate materials are required to have high heat resistance, low Dk (Low dielectric constant )/Df (Low dissipation factor, low dielectric loss factor) and Low CTE (Low Coefficient of thermal expansion Low thermal expansion coefficient) and other performances, and the copper-clad plate/PCB prepared from the traditional thermoplastic prepreg is difficult to meet the requirements at the same time.

Disclosure of Invention

The embodiment of the invention provides a preparation method of a prepreg and the prepreg, which can improve the heat resistance of the prepared prepreg and reduce the dielectric constant and dielectric loss factor of the prepreg.

In order to solve the technical problems, the invention adopts a technical scheme that:

the preparation method of the prepreg comprises the following steps:

providing an electronic glass fiber cloth and a liquid crystal high polymer film, sequentially stacking the electronic glass fiber cloth and the liquid crystal high polymer film to form a laminated structure, and arranging the electronic glass fiber between the liquid crystal high polymer films; providing a hot-pressing die, dedusting the hot-pressing die, and coating oil films on the upper hot-pressing surface and the lower hot-pressing surface of the hot-pressing die; placing the laminated structure between an upper hot-pressing surface and a lower hot-pressing surface for preheating, and hot-pressing the preheated laminated structure; transferring the hot-pressing die to a cold-pressing table top, and cold-pressing the laminated structure between the upper hot-pressing surface and the lower hot-pressing surface; and taking out the laminated structure from the hot-pressing die to obtain the prepreg.

In one embodiment, the step of dedusting the hot press mold includes: blowing off dust on the upper hot pressing surface and the lower hot pressing surface.

In one embodiment, the step of coating the oil film on the upper and lower hot pressing surfaces of the hot pressing mold includes: spraying a release agent at a predetermined interval from the upper hot pressing surface and the lower hot pressing surface, and drying the hot pressing mold to form a release oil film on the upper hot pressing surface and the lower hot pressing surface.

In an embodiment, after the step of drying the hot press mold to form a release oil film on the upper hot press surface and the lower hot press surface, the method further comprises: and (3) carrying out secondary spraying of release agents on the upper hot-pressing surface and the lower hot-pressing surface, and then carrying out natural air drying.

In one embodiment, the step of preheating the laminated structure between the upper hot pressing surface and the lower hot pressing surface is performed at a preheating temperature of 320 ° for a preheating time of 3min.

In one embodiment, in the step of hot-pressing the preheated laminated structure, the step of: the hot pressing temperature is 320-340 ℃, the pressing time is 5-8min, the pressure is 10-20Bar, the number of times of air exhaust is 1-2 times, the air exhaust time is 2-5S, and the air exhaust die closing time is 3-6S.

In one embodiment, the predetermined interval is 20-30 cm.

In one embodiment, the step of placing the laminated structure between the upper and lower hot press surfaces prior to preheating further comprises: cutting the laminated structure to make the shape of the electronic glass fiber cloth and the shape of the liquid crystal high polymer film the same.

In one embodiment, the electronic glass cloth is NE-glass cloth.

The invention also provides a prepreg which is prepared by the preparation method of the prepreg.

The embodiment of the invention has the beneficial effects that: compared with the prior art, the embodiment of the invention adopts the liquid crystal high molecular polymer as a resin substitute, has better flame retardance compared with other thermoplastic resins (such as PP, PET, PC and the like), and has the characteristics of high heat resistance and low dielectric loss because the glass fiber cloth is used as a skeleton to support in LCP, and the dielectric property of the compounded prepreg is not obviously reduced by compounding the glass fiber cloth with the LCP resin.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and that other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural view of a prepreg according to an embodiment of the present invention;

FIG. 2 is a flow chart of a method of preparing a prepreg according to an embodiment of the invention;

fig. 3 is a partial step flowchart of a method for preparing a prepreg according to an embodiment of the invention.

Reference numerals illustrate:

10. a prepreg; 100. a liquid crystal high molecular polymer film; 200. an electronic glass fiber cloth.

Detailed Description

In order that the invention may be readily understood, a more particular description thereof will be rendered by reference to specific embodiments that are illustrated in the appended drawings. It will be understood that when an element is referred to as being "fixed" to another element, it can be directly on the other element or one or more intervening elements may be present therebetween. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used in this specification includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, the present invention provides a prepreg 10, which includes an electronic glass fiber cloth 100 and a liquid crystal polymer film 200, wherein the electronic glass fiber cloth 100 and the liquid crystal polymer film 200 are sequentially stacked, and the electronic glass fiber cloth 100 is disposed between the liquid crystal polymer films 200.

The prepreg 10 of the invention can be used as a copper-clad plate base material or a PP bonding sheet in high-end PCB boards such as HDI, IC carrier boards and similar carrier boards. The specific use environment of the prepreg should be determined according to practical situations, and the application is not limited.

The prepreg is prepared by the following preparation method.

Referring to fig. 2, the preparation method of the prepreg of the present application includes the following steps:

s1, providing an electronic glass fiber cloth and a liquid crystal high polymer film, sequentially stacking the electronic glass fiber cloth and the liquid crystal high polymer film to form a laminated structure, and arranging the electronic glass fiber between the liquid crystal high polymer films.

The electronic glass fiber cloth is a framework of the prepreg, can improve the strength of the liquid crystal high polymer film, maintains the structural stability of the liquid crystal high polymer film, can be one or more layers, and can change the thickness of the prepreg by increasing the number of layers of the electronic glass fiber cloth.

Illustratively, the electronic glass cloth may be a NE-glass cloth. The NE-glass fiber cloth is used for manufacturing high-performance signal transmission products, has low dielectric constant and dielectric loss, lower thermal expansion coefficient, excellent dimensional stability and higher hardness, the dielectric constant can reach 4.4 (under the condition of 1 MHz), and in addition, the glass fibers are distributed uniformly.

The liquid crystal polymer (Liquid Crystal Polymer, LCP for short) is an intermediate substance between isotropic liquid and completely ordered crystal, which has good fluidity of liquid and complete ordered crystal structure, and has less transmission loss after moisture absorption.

In this step, the laminated structure resembles a sandwich structure.

S2, providing a hot-pressing die, dedusting the hot-pressing die, and coating oil films on the upper hot-pressing surface and the lower hot-pressing surface of the hot-pressing die.

In this step, the hot-press mold may be a flat-plate hot-press mold having an upper platen and a lower platen, the surface of the upper platen, which is cooperatively connected with the lower platen, being an upper hot-press surface, and the surface of the lower platen, which is connected with the upper platen, being a lower hot-press surface, and the upper hot-press surface and the lower hot-press surface (hereinafter also referred to as hot-press surfaces) need to be cleaned in order to prevent dust from being pressed into the liquid crystal polymer. In some examples, the lower hot pressing surface may be a "concave" shaped surface, while the upper hot pressing surface may be planar.

Referring to fig. 3, in an embodiment, step S2 further includes the following steps:

s20, blowing dust on the upper hot-pressing surface and the lower hot-pressing surface. For example, dust on the upper and lower hot pressing surfaces can be blown off using an air gun, and this embodiment can avoid introducing liquid impurities, compared with a method using liquid cleaning, thereby reducing the influence of liquid impurities on the product during hot pressing.

S21, spraying a release agent at a preset interval from the upper hot-pressing surface and the lower hot-pressing surface, and drying the hot-pressing die to form release oil films on the upper hot-pressing surface and the lower hot-pressing surface.

In this step, the predetermined interval is set to enhance the uniformity of the release agent on the upper and lower hot pressing surfaces, facilitate the formation of an oil film, and enable the formed oil film to have a thin thickness, and less release agent remains on the mold surface after drying, causing less occurrence of the condition of affecting the product performance due to the adhesion of the release agent to the product.

In some examples, the predetermined spacing is 20-30 cm, in particular, the predetermined spacing may be 20, 25, or 30 cm. After the release agent is sprayed, drying is carried out, so that the oil film can be rapidly formed into a release oil film, and the release oil film can prevent the liquid crystal high polymer from being adhered to the upper hot-pressing surface or the lower hot-pressing surface.

In this step, the mold release agent may be one of three types of mold release agents, such as Dajin GA9750M/GA9700M/GA3000, and the highest temperature resistance may be 380 ℃.

In the step, the drying is to form a complete oil film for the release agent to cover the upper hot pressing surface and the lower hot pressing surface, so that the condition that the product is stuck to the hot pressing surface due to the fact that the release agent is not sprayed on part of the area is prevented.

S22, performing secondary spraying of release agents on the upper hot-pressing surface and the lower hot-pressing surface, and then performing natural air drying.

In this step, the distribution of the oil film may be uneven during the drying process, and in order to further prevent the liquid crystal polymer from sticking to the mold, the mold release agent is sprayed for the second time, it is worth mentioning that the mold is naturally air-dried after the second spraying in this step, so that the influence of artificial drying on the oil film forming is reduced, and the mold release agent can remain on the hot pressing surface to promote the oil film formation.

S3, placing the laminated structure between the upper hot-pressing surface and the lower hot-pressing surface for preheating, and hot-pressing the preheated laminated structure.

In this step, the laminated structure was put into a step of preheating between the upper hot-pressing surface and the lower hot-pressing surface at a preheating temperature of 320 ° for a preheating time of 3min. The aim of preheating is to make the laminated structure approach the hot-pressing temperature, and the hot-pressing temperature can be reached only by short heating when the hot-pressing step is carried out.

In the step, the hot pressing temperature is 320-340 ℃, the pressing time is 5-8min, the pressure is 10-20Bar, the exhaust times are 1-2 times, the exhaust time is 2-5S, and the exhaust die closing time is 3-6S.

The steps before step S3 further include:

s30, cutting the laminated structure to enable the shape of the electronic glass fiber cloth to be the same as that of the liquid crystal high polymer film.

In this step, the laminated structure should be completely placed in the hot-pressing mold, so as to avoid that part of the materials extend out of the mold during hot-pressing, and the hot-pressing cannot be completed. Specifically, the dimensions of the laminated structure should be smaller than the dimensions of the upper and lower hot pressing surfaces.

S4, transferring the hot-pressing die to a cold-pressing table top, and cold-pressing the laminated structure between the upper hot-pressing surface and the lower hot-pressing surface.

In the step, the whole hot-pressing die is transferred to a cold-pressing table top, in the process, the laminated structure is gradually cooled, and the laminated structure is shaped during cold pressing, so that the prepreg is obtained.

And S5, taking out the laminated structure from the hot-pressing die to obtain the prepreg.

Referring to table 1, the present application uses the liquid crystal high molecular polymer as a resin substitute, which has better flame retardance than other thermoplastic resins (such as PP, PET, PC, etc.), and uses the glass fiber cloth with low dielectric constant to be compounded with the LCP resin, so that the dielectric property of the compounded prepreg is not obviously reduced, and the mechanical property of the prepreg is improved compared with the pure film of the LCP because the glass fiber cloth is used as a skeleton to support the LCP, therefore, the prepreg prepared by the preparation method of the prepreg has the characteristics of high heat resistance and low dielectric loss.

Referring to table 1, the prepreg of the application has the characteristics of excellent dielectric property, good dimensional stability, high temperature resistance, low loss and the like, and the copper-clad plate/PCB prepared by the prepreg of the application has excellent comprehensive performance and can be subjected to SMT, so that the problem that the thermoplastic copper-clad plate/PCB cannot be applied to high-end PCB boards such as HDI, IC carrier boards and carrier-like boards is solved.

The following describes aspects of the present application in terms of several specific embodiments.

Example 1

A high heat-resistant and low-loss thermoplastic prepreg and a preparation method thereof comprise the following steps of;

2 pieces of 25-um LCP resin film with the size not larger than the die cavity and 1 piece of electronic glass fiber cloth with the same size are prepared, wherein the marks of the 25-um LCP resin film are as follows: the brand of the Kuraray CTQ-25 and the electronic glass fiber cloth is as follows: 1067-30um. Stacking glass fiber cloth according to a sandwich structure, wherein the middle layer is 1067 glass fiber cloth, and the upper layer and the lower layer are CTQ-25LCP resin films;

cleaning a flat hot-pressing die, blowing dust on the surfaces of the upper die and the lower die by using an air gun, and spraying the dust on the surfaces of the upper die and the lower die by using a release agent with the high temperature resistance of more than 300 ℃ at a distance of 20 cm to 30cm from the surfaces of the upper die and the lower die, wherein the release agent has the brand of high temperature resistance: RD-518, then carrying out secondary spraying, and naturally air-drying after spraying.

Placing the laminated materials into a mold cavity, closing the mold, preheating at 320 ℃ for 3min, starting hot pressing after the preheating is finished, wherein the hot pressing temperature is 330 ℃, the pressing time is 5min, the pressure is 10Bar, the times of air exhaust are 1 time, the air exhaust time is 2S, and the air exhaust mold closing time is 3S;

after the hot pressing is finished, the whole die is transferred to a cold pressing table top for cold pressing, the die is opened when the temperature of the die is reduced to be lower than 50 ℃ for cold pressing, the pressed thermoplastic prepreg is taken out, and the thermoplastic prepreg is cut and stacked according to the required size to obtain a finished thermoplastic prepreg product.

Example 2

2 pieces of 25-um LCP resin film with the size not larger than the die cavity and 1 piece of electronic glass fiber cloth with the same size are prepared, wherein the marks of the 25-um LCP resin film are as follows: the brand of the Kuraray CTQ-25 and the electronic glass fiber cloth is as follows: 1027-18um. Stacking glass fiber cloth according to a sandwich structure, wherein the middle layer is 1027 glass fiber cloth, and the upper layer and the lower layer are CTQ-25LCP resin films;

Example 3

2 pieces of 25-um LCP resin film with the size not larger than the die cavity and 1 piece of electronic glass fiber cloth with the same size are prepared, wherein the marks of the 25-um LCP resin film are as follows: the brand of the Kuraray CTQ-25 and the electronic glass fiber cloth is as follows: 1035-28um. Stacking glass fiber cloth according to a sandwich structure, wherein the middle layer is 1035 glass fiber cloth, and the upper layer and the lower layer are CTQ-25LCP resin films;

Example 4

Placing the laminated materials into a mold cavity, closing the mold, preheating at 320 ℃ for 3min, starting hot pressing after the preheating is finished, wherein the hot pressing temperature is 330 ℃, the pressing time is 8min, the pressure is 20Bar, the times of air exhaust are 2 times, the air exhaust time is 5S, and the air exhaust mold closing time is 6S;

Comparative example 1

High-heat-resistance low-loss thermoplastic prepreg and preparation method thereof

2 sheets of 25-um LCP resin film were prepared, the size of which was not larger than the die cavity, wherein the 25-um LCP resin film was identified as: kuraray CTQ-25. 2 sheets of 25-um LCP resin film are stacked up and down;

Comparative example 2

2 sheets of 50-um LCP resin film were prepared, the size of which was not larger than the die cavity, and 25-um LCP resin film was given the brand name: kuraray CTQ-50. 2 sheets of 50-um LCP resin film are stacked up and down;

TABLE 1

It should be noted that the description of the present invention and the accompanying drawings illustrate preferred embodiments of the present invention, but the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, which are not to be construed as additional limitations of the invention, but are provided for a more thorough understanding of the present invention. The above-described features are further combined with each other to form various embodiments not listed above, and are considered to be the scope of the present invention described in the specification; further, modifications and variations of the present invention may be apparent to those skilled in the art in light of the foregoing teachings, and all such modifications and variations are intended to be included within the scope of this invention as defined in the appended claims.

Claims

1. The preparation method of the prepreg is characterized by comprising the following steps of:

providing an electronic glass fiber cloth and a liquid crystal high polymer film, sequentially stacking the electronic glass fiber cloth and the liquid crystal high polymer film to form a laminated structure, and arranging the electronic glass fiber between the liquid crystal high polymer films;

providing a hot-pressing die, dedusting the hot-pressing die, and coating oil films on the upper hot-pressing surface and the lower hot-pressing surface of the hot-pressing die;

placing the laminated structure between an upper hot-pressing surface and a lower hot-pressing surface for preheating, and hot-pressing the preheated laminated structure;

transferring the hot-pressing die to a cold-pressing table top, and cold-pressing the laminated structure between the upper hot-pressing surface and the lower hot-pressing surface;

and taking out the laminated structure from the hot-pressing die to obtain the prepreg.

2. The method of preparing a prepreg according to claim 1, wherein the step of removing dust from the hot press mold comprises:

blowing off dust on the upper hot pressing surface and the lower hot pressing surface.

3. The method of preparing a prepreg according to claim 1, wherein the step of coating oil films on the upper and lower hot pressing surfaces of the hot pressing mold comprises:

spraying a release agent at a predetermined interval from the upper hot pressing surface and the lower hot pressing surface, and drying the hot pressing mold to form a release oil film on the upper hot pressing surface and the lower hot pressing surface.

4. The method of preparing a prepreg according to claim 3, wherein the step of drying the hot press mold to form a release oil film on the upper hot press surface and the lower hot press surface further comprises:

and (3) carrying out secondary spraying of release agents on the upper hot-pressing surface and the lower hot-pressing surface, and then carrying out natural air drying.

5. A method of preparing a prepreg according to claim 3, wherein the step of preheating the laminate structure between the upper hot-pressing surface and the lower hot-pressing surface has a preheating temperature of 320 ° and a preheating time of 3min.

6. The method for preparing a prepreg according to claim 1, wherein the step of hot-pressing the preheated laminated structure comprises: the hot pressing temperature is 320-340 ℃, the pressing time is 5-8min, the pressure is 10-20Bar, the number of times of air exhaust is 1-2 times, the air exhaust time is 2-5S, and the air exhaust die closing time is 3-6S.

7. A method of preparing prepregs according to claim 3 in which the predetermined spacing is 20-30 cm.

8. The method of preparing a prepreg according to claim 1, wherein the step of placing the laminate structure between the upper hot-pressing surface and the lower hot-pressing surface for preheating further comprises:

cutting the laminated structure to make the shape of the electronic glass fiber cloth and the shape of the liquid crystal high polymer film the same.

9. The method for preparing a prepreg according to claim 1, wherein the electronic glass cloth is NE-glass cloth.

10. A prepreg prepared by the method of any one of claims 1-9.