Copper-clad plate for high-speed line

Abstract

The copper-clad plate for the high-speed line comprises an insulating layer and copper foils arranged on the surface of one side or two sides of the insulating layer, the insulating layer is formed by alternately stacking PI film prepregs and glass fiber cloth, and the outermost layer of the insulating layer is the PI film prepreg; the PI film prepreg is formed by impregnating a PI film in a resin glue solution. According to the copper-clad plate for the high-speed line, the components are relatively stable, the mass percent is relatively stable, fluctuation of dielectric constants is avoided, the requirement for thickness tolerance of plates is met, and the copper-clad plate has low dielectric constants and dielectric loss constants.

Description

Technical Field

[0001] This utility model belongs to the field of basic materials technology in the field of electronic information, and more specifically, it relates to a copper-clad laminate for high-speed and high-frequency circuit boards. Background Technology

[0002] With the advent of the 5G era, people have higher demands for information and communication technologies, requiring greater communication bandwidth. Simultaneously, communication equipment is developing towards miniaturization and convenience. To obtain more information, people are increasing communication frequencies to increase bandwidth. This necessitates that copper-clad laminates (CCLs), the basic material for printed circuit boards in electronic products, possess low dielectric constants and dielectric losses under high-frequency conditions. However, in addition to low dielectric constants and dielectric loss constants, CCLs for high-speed circuit boards must also possess stable dielectric properties. This requires consistent and uniform dielectric layer thickness as well as good thermal conductivity. Traditional CCLs are simply layered structures, where copper foil layers are directly hot-pressed onto both sides of a prepreg. While this layered CCL manufacturing process is simple, it struggles to meet the diverse requirements of high-speed circuit boards, such as ensuring dielectric layer consistency and thickness uniformity, minimizing thickness tolerances, achieving good thermal conductivity, and providing good electrical insulation. Utility Model Content

[0003] The purpose of this invention is to provide a copper-clad laminate for high-speed circuits with stable dielectric properties and low dielectric constant and dielectric loss constant.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A copper-clad laminate for high-speed lines includes: an insulating layer and copper foil disposed on one or both sides of the insulating layer; the insulating layer is formed by alternating layers of PI film prepreg and glass fiber cloth, the outermost layer of the insulating layer being the PI film prepreg; the PI film prepreg is formed by impregnating a PI film with a resin solution.

[0006] In some embodiments, the thickness of the fiberglass cloth is less than 0.15 mm.

[0007] In some embodiments, the thickness of the PI film is 0.05 mm to 0.1 mm.

[0008] In some embodiments, the thickness of the PI film prepreg is 0.09 mm to 0.2 mm.

[0009] In some embodiments, the PI film has a surface tension ≥38 dynes and a surface roughness of 0.08 to 0.16.

[0010] In some embodiments, the PI film undergoes double-sided corona treatment to create an uneven surface.

[0011] As can be seen from the above technical solutions, the insulation layer structure of the copper-clad laminate for high-speed lines of this utility model uses a prepreg made of resin impregnated with PI film. This improves the low dielectric constant and low loss of the copper-clad laminate composite material from two aspects: resin composition and reinforcing materials. In the laminated structure, the prepreg made of PI film is alternately layered with electronic-grade thin glass cloth, solving the problem of the stability of the ratio of reinforcing materials to resin in the board. Simultaneously, because the glass cloth is not impregnated with resin, resin flow does not occur during pressing, making it easier to control the thickness tolerance of the board within a very small range, thus maintaining a stable dielectric constant and dielectric loss constant. The components in the copper-clad laminate structure of this utility model are relatively stable, and the mass percentage is also relatively stable, avoiding fluctuations in the dielectric constant and meeting the thickness tolerance requirements of the board. The dielectric constant of the copper-clad laminate of this utility model can be controlled to be less than 3.70, and the dielectric loss constant is less than 0.0075. Attached Figure Description

[0012] To more clearly illustrate the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a layer structure diagram of the copper-clad laminate according to an embodiment of the present invention;

[0014] Figure 2 This is a flowchart of the copper-clad laminate manufacturing method according to an embodiment of the present invention. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings. In the detailed description of the embodiments of the present invention, for ease of explanation, the drawings illustrating the device structure will be partially enlarged without adhering to the general scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. It should be noted that the drawings are in a simplified form and use non-precise scales, solely for the purpose of conveniently and clearly illustrating the embodiments of the present invention. Additionally, in the description of this application, terms such as "first" and "second" are used only to distinguish descriptions and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Terms such as "positive," "negative," "bottom," "upper," "lower," "front," "rear," "left," and "right" indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0016] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0017] Traditional copper-clad laminates (CCLs) consist of stacked copper foil layers and prepreg layers, with the prepreg acting as an insulating layer and the copper foil layer as a conductive layer. The copper foil layer is located on both sides of the insulating layer, and the CCL is formed by hot pressing. This simple stacking structure makes it difficult to ensure the uniformity of the board thickness and the consistency of the dielectric layer, thus affecting the stability of the dielectric properties of the CCL.

[0018] To improve the performance of copper clad laminates, fiberglass cloth can be used as a reinforcing material. The fiberglass cloth is impregnated with resin to make a semi-cured sheet. However, the impregnated fiberglass cloth will experience resin flow during pressing, resulting in large thickness tolerance of the board and making it difficult to control the dielectric constant of the board in a stable state.

[0019] To address the issue of unstable dielectric properties in copper-clad laminates, this invention improves the composition of the resin adhesive and uses PI film as a reinforcing material for the prepreg. The resin adhesive is impregnated in the PI film, dried at high temperature to form a prepreg, and then laminated with thin glass fiber cloth. Finally, it is pressed under high temperature and pressure to form the insulating layer of the copper-clad laminate.

[0020] The insulating layer of this copper-clad laminate is made of a prepreg made of PI film impregnated with resin adhesive. This solves the problems of low dielectric constant and low loss of composite materials from the aspects of resin composition and reinforcing materials. In terms of the laminate structure, the prepreg made of PI film is alternately stacked with thin glass fiber cloth to solve the problem of the stability of the ratio of reinforcing materials and resin in the board. Moreover, the glass fiber cloth is not impregnated with resin, so there will be no resin flow during pressing. This makes it easier to control the thickness tolerance of the board within a very small range, so that the dielectric constant and dielectric loss constant of the board can be kept in a stable state.

[0021] like Figure 1 As shown, the high-speed line copper-clad laminate of this embodiment includes copper foil 1 and an insulating layer, wherein the insulating layer is composed of alternating layers of PI film prepreg 2 and thin fiberglass cloth 3. The laminate structure of the copper-clad laminate can be: copper foil + PI film prepreg + thin fiberglass cloth + PI film prepreg + ... + thin fiberglass cloth + PI film prepreg + copper foil. If both surfaces of the insulating layer have copper foil, it is a double-sided copper-clad laminate; if only one side has copper foil, it is a single-sided copper-clad laminate. The PI film prepreg is the outermost layer of the insulating layer; that is, it is the PI film prepreg, not the thin fiberglass cloth, that is in contact with the copper foil.

[0022] The thin glass fiber cloth of this invention has a thickness of less than 0.15mm and is an electronic-grade alkali-free plain-weave glass fiber cloth. Glass fiber cloths of models 1506, 3313, 2313, 2116, 1080, and 106 can be used.

[0023] The resin solution used in the preparation of the prepreg of this invention comprises: bisphenol A cyanate resin, modified polyphenylene ether resin, bicyclic cyclic epoxy resin, catalyst, and cage-like silsesquioxane filler. The resin solution prepared from these materials exhibits low dielectric constant and low dielectric loss. This resin solution also possesses high bonding strength, high flexibility, high ductility, and good heat resistance. In specific applications, acetylacetone transition metal compounds, such as aluminum acetylacetone, zinc acetylacetone, nickel acetylacetone, and cobalt acetylacetone, can be used as catalysts.

[0024] Furthermore, the amounts (parts by weight) of each component in the resin solution of this invention are as follows: 35-65 parts of bisphenol A cyanate resin, 15-30 parts of modified polyphenylene ether resin, 10-20 parts of bicyclic cyclic epoxy resin, 5-10 parts of cage-like silsesquioxane, and 0.02-0.2 parts of catalyst. After mixing the above components at room temperature, they are added to a solvent and stirred until homogeneous to obtain the resin solution. In specific applications, the solvent can be methyl ethyl ketone (MEK), with 30-100 parts of MEK solvent.

[0025] The PI film prepreg of this invention uses PI film as the reinforcing material. The PI film is impregnated with resin solution using a coating machine, and then baked at high temperature until the resin solution is in a semi-cured state. The thickness of the PI film can be 0.05mm to 0.1mm. The thickness of the PI film prepreg can be 0.09mm to 0.2mm.

[0026] This invention relates to a PI film prepreg, which uses PI film (polyimide film) as the reinforcing material. Polyimide is a low dielectric constant material, and prepreg made by impregnating this low dielectric constant material with a low dielectric constant resin can maintain the dielectric constant and dielectric loss value of the substrate in a stable state.

[0027] Furthermore, the PI film of this invention is a PI film that has undergone double-sided corona treatment. The steps for corona treatment of the PI film are as follows:

[0028] PI films undergo surface treatment under high-voltage, high-frequency spark discharge impact, resulting in an uneven surface. Specifically, spark discharges of 5KV–30KV and 10–25KHz are used to impact the PI film surface. Since this process is performed in air, the PI film surface is roughened by the impact. After the discharge impact, the uneven surface, resembling small tubular grooves, can be observed using a high-magnification transmission electron microscope. The surface tension of the corona-treated PI film is ≥38 dynes, and the surface roughness Ra is 0.08–0.16. Corona treatment can improve the wettability and specific surface area of ​​the PI film surface.

[0029] Furthermore, the corona-treated PI film undergoes surface activation treatment using a silane coupling agent. By coating the silane coupling agent onto the surface of the PI film, a chemical reaction occurs, forming a new surface layer. This new surface layer further improves the surface properties of the PI film, enhancing its wettability and adhesion, thereby improving the heat resistance of the copper-clad laminate.

[0030] Specifically, the siloxane coupling agent can be a conventional coupling agent available on the market, such as vinylsilane, aminosilane, epoxysilane, mercaptosilane, and methacryloxysilane. The activated PI film is used as a reinforcing material, impregnated with a resin solution having a low dielectric constant and low loss using a coating machine, and then baked at high temperature to a semi-cured state to form a PI film prepreg.

[0031] Depending on the required thickness of the substrate, a corresponding number of PI film prepregs 2 and thin glass fiber cloth 3 are alternately stacked together and hot-pressed together with the copper foil layer at 175-200°C in a hot press, and cured for 80-110 minutes to form a copper-clad laminate for high-speed circuits.

[0032] The present invention will be further described below through specific embodiments. Unless otherwise specified, the reagents, materials and instruments used in the following description are all conventional reagents, materials and instruments, which are commercially available, and the reagents involved can also be synthesized by conventional synthesis methods.

[0033] Example 1

[0034] like Figure 2 As shown, the steps of the copper-clad laminate preparation method in this embodiment are as follows:

[0035] S1. Preparation of resin solution; In the preparation of resin solution, each raw material is in parts by weight. 45 parts of bisphenol A cyanate resin, 20 parts of bicyclic cyclic epoxy resin, 30 parts of modified polyphenylene ether resin, and 0.03 parts of cobalt acetylacetonate catalyst are dissolved in methyl ethyl ketone solvent, and then 5 parts of cage-like silsesquioxane are added and stirred evenly to obtain the resin solution; In this embodiment, the bisphenol A cyanate resin is model C01PS, the bicyclic cyclic epoxy resin is model UVR6105, the modified polyphenylene ether resin is model OPE-2ST2200, and the cage-like silsesquioxane is model PEG POSS;

[0036] S2. The PI film with a thickness of 0.075 mm, which has been treated with corona and surface activation, is immersed in the resin solution obtained in step S1 and baked to obtain a semi-cured sheet. In this embodiment, the thickness of the resin layer on the surface of the PI film semi-cured sheet is 0.08 mm to 0.12 mm, and the thickness of a single cured sheet obtained after curing is 0.150 to 0.180 mm.

[0037] S3. Five prepreg sheets and four sheets of fiberglass cloth are stacked together. An electrolytic copper foil is then applied to one or both sides of the stacked prepreg sheets. In this embodiment, an electrolytic copper foil is applied to both sides. The thickness of the electrolytic copper foil is 0.018 mm. After hot pressing, a copper-clad laminate for high-speed circuits with a thickness of 1.3 mm is obtained. This embodiment uses 1506 type fiberglass cloth, which has a finer surface. This allows for relative stability in the ratio of reinforcing material to resin in the board and better control of resin flow during the board pressing process. It also controls the uniformity and consistency of the board thickness, thereby keeping the dielectric constant and dielectric loss value of the board in a more stable state.

[0038] The dielectric constant (1MHz) and dielectric loss constant (1MHz) of the multiple copper-clad laminates prepared in this embodiment were tested and found to be 3.68, 3.67, 3.68, 3.66, 3.67 and 0.0072, 0.0071, 0.0073, 0.0071, 0.0072, respectively. It can be seen that the dielectric constant and dielectric loss constant of the copper-clad laminates are relatively stable, basically around 3.67 and 0.0072.

[0039] Example 2

[0040] S1. Preparation of resin solution; The main difference between the resin solution in this embodiment and the resin solution in Example 1 is the amount of each component. In the preparation of the resin solution, each raw material is expressed in parts by weight. 50 parts of bisphenol A cyanate resin, 20 parts of bicyclic cyclic epoxy resin, 30 parts of modified polyphenylene ether resin, and 0.035 parts of cobalt acetylacetonate catalyst are dissolved in methyl ethyl ketone solvent, and then 5 parts of cage-like silsesquioxane are added and stirred evenly to obtain the resin solution.

[0041] S2. The PI film with a thickness of 0.085 mm, which has been treated with corona discharge and surface activation, is immersed in the resin solution obtained in step S1 and baked to obtain a semi-cured sheet. In this embodiment, the thickness of the resin layer on the surface of the PI film semi-cured sheet is 0.08 mm to 0.12 mm, and the thickness of a single cured sheet obtained after curing is 0.160 to 0.190 mm.

[0042] S3. Five prepreg sheets and four sheets of fiberglass cloth are stacked together. An electrolytic copper foil is then applied to one or both sides of the stacked prepreg sheets. In this embodiment, an electrolytic copper foil is applied to both sides. The thickness of the electrolytic copper foil is 0.018 mm. After hot pressing, a copper-clad laminate for high-speed circuits with a thickness of 1.5 mm is obtained. This embodiment uses type 2116 fiberglass cloth.

[0043] The dielectric constant (1MHz) and dielectric loss constant (1MHz) of the copper-clad laminate prepared in this embodiment were tested. The dielectric constant and dielectric loss constant of the prepared copper-clad laminate were approximately 3.65 and 0.0068, respectively.

[0044] Example 3

[0045] S1. Preparation of resin solution; The main difference between the resin solution in this embodiment and the resin solution in Example 1 is the amount of each component. In the preparation of the resin solution, each raw material is expressed in parts by weight. 50 parts of bisphenol A cyanate resin, 10 parts of bicyclic cyclic epoxy resin, 30 parts of modified polyphenylene ether resin, and 0.04 parts of cobalt acetylacetonate catalyst are dissolved in methyl ethyl ketone solvent, and then 5 parts of cage-like silsesquioxane are added and stirred evenly to obtain the resin solution.

[0046] S2. The PI film with a thickness of 0.100 mm, which has undergone corona treatment and surface activation, is immersed in the resin solution obtained in step S1 and baked to obtain a semi-cured sheet. In this embodiment, the thickness of the resin layer on the surface of the PI film semi-cured sheet is 0.08 mm to 0.12 mm, and the thickness of a single cured sheet obtained after curing is 0.180 to 0.210 mm.

[0047] S3. Five prepreg sheets and four sheets of fiberglass cloth are stacked together. An electrolytic copper foil is then applied to one or both sides of the stacked prepreg sheets. In this embodiment, an electrolytic copper foil is applied to both sides. The thickness of the electrolytic copper foil is 0.018 mm. After hot pressing, a copper-clad laminate for high-speed circuits with a thickness of 1.3 mm is obtained. This embodiment uses 1080 type fiberglass cloth.

[0048] The dielectric constant (1MHz) and dielectric loss constant (1MHz) of the copper-clad laminate prepared in this embodiment were tested. The dielectric constant and dielectric loss constant of the prepared copper-clad laminate were approximately 3.62 and 0.0065, respectively.

[0049] This invention employs an insulating layer composed of alternating PI film prepreg and thin glass cloth. The prepreg is made by impregnating a low dielectric constant resin with PI film as the reinforcing material. It has an organic content of 100%. The high organic content in the PI film prepreg ensures the thickness of the "cream layer" between the copper foil and the substrate, even when using thicker copper foil (with higher copper teeth). The low dielectric constant and low loss of the copper-clad laminate are achieved through the copper foil structure and the prepreg structure.

[0050] The process layer structure consists of alternating PI film prepreg and thin glass cloth, which increases the contact area between the two interfaces, reduces fluidity, ensures the stability of the ratio of reinforcing material to resin in the board, and better controls the uniformity of the board, ensuring that the thickness tolerance is narrowed within a certain range, thereby keeping the dielectric constant and dielectric loss value of the board in a stable state.

[0051] The above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this utility model. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model should be covered within the scope of this utility model.

Claims

1. Copper-clad laminates for high-speed lines, including: An insulating layer and copper foil disposed on one or both surfaces of the insulating layer; characterized in that: The insulating layer is composed of alternating layers of PI film prepreg and glass fiber cloth, with the outermost layer being the PI film prepreg; the PI film prepreg is formed by impregnating a PI film with resin.

2. The copper-clad laminate for high-speed lines as described in claim 1, characterized in that: The thickness of the fiberglass cloth is less than 0.15 mm.

3. The copper-clad laminate for high-speed lines as described in claim 1, characterized in that: The thickness of the PI film is 0.05 mm to 0.1 mm.

4. The copper-clad laminate for high-speed lines as described in claim 1, characterized in that: The thickness of the PI film semi-cured sheet is 0.09 mm to 0.2 mm.

5. The copper-clad laminate for high-speed lines as described in claim 1, characterized in that: The PI film has a surface tension ≥38 dynes and a surface roughness of 0.08~0.

16.

6. The copper-clad laminate for high-speed lines as described in claim 1 or 5, characterized in that: The PI film undergoes double-sided corona treatment to create an uneven surface.

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