Low thermal expansion high-frequency copper clad plate

Abstract

The utility model discloses a low thermal expansion high frequency copper clad plate, including the substrate and the copper sheet of covering at least one surface of substrate, the substrate includes flat glass fiber cloth and resin filler layer, the flat glass fiber cloth is woven by a plurality of warp and a plurality of weft interlaced, and a plurality of meshes are formed between warp and weft, the resin filler layer is filled in the mesh aperture, and the resin filler layer evenly disperses with silica powder in. The utility model forms the skeleton through the flat glass fiber cloth, and the synergistic effect of the resin filler layer with the silica powder dispersed in, double constraint resin matrix thermal expansion, wherein the flat structure of flat glass fiber cloth reduces the interlayer gap, provides more effective support for Z axis, and the silica powder is evenly distributed in the resin and forms a large number of rigid nodes, which significantly increases the path resistance of resin expansion, thereby greatly reducing the thermal expansion coefficient of Z axis, effectively preventing the fracture of metallized hole.

Description

Technical Field

[0001] This utility model relates to the field of electronic materials technology, and in particular to a low thermal expansion high frequency copper-clad laminate. Background Technology

[0002] Copper clad laminate is the core substrate for manufacturing printed circuit boards. With the rapid development of high-frequency applications such as 5G communication, automotive radar, and aerospace, higher requirements are placed on the high-frequency performance of copper clad laminate. However, the dielectric properties of ordinary epoxy resin-glass fiber cloth substrate deteriorate at high frequencies, which cannot meet the application requirements.

[0003] Currently, most mainstream high-frequency copper-clad laminates use polytetrafluoroethylene or modified hydrocarbon resin systems. However, the coefficient of thermal expansion of these polymer resins is usually much higher than that of copper as a conductor. This mismatch in the coefficient of thermal expansion, especially in the Z-axis direction perpendicular to the board surface, will generate huge thermal stress under the heat shock of soldering during the assembly process or the temperature cycle during equipment use. This stress can easily cause the metallized holes connecting different layers of circuits to break, resulting in open circuits and seriously affecting the reliability of electronic equipment.

[0004] To address these issues, we propose a low-thermal-expansion, high-frequency copper-clad laminate. Utility Model Content

[0005] The purpose of this invention is to provide a low thermal expansion high-frequency copper-clad laminate to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A low thermal expansion high-frequency copper-clad laminate includes a substrate and a copper sheet coated on at least one surface of the substrate. The substrate includes a flat glass fiber cloth and a resin filler layer. The flat glass fiber cloth is woven from a plurality of warp and weft yarns in a crisscross pattern, and a plurality of meshes are formed between the warp and weft yarns. The resin filler layer fills the mesh pores, and silica powder is uniformly dispersed in the resin filler layer.

[0008] In a further embodiment, the flat glass fiber cloth is an S-grade glass fiber cloth or an NE-type glass fiber cloth.

[0009] In a further embodiment, the resin filler layer is made of modified hydrocarbon resin or cyanate ester resin.

[0010] In a further embodiment, the particle size range of the silica powder is 50-500 nm.

[0011] In a further embodiment, the silica powder has a mass fraction of 30-60% in the resin filler layer.

[0012] In a further embodiment, the dispersion density of the silica powder in the resin filler layer gradually increases from the flat glass fiber cloth side to the copper sheet side.

[0013] In a further embodiment, the copper sheet is a low-profile electrolytic copper foil or a rolled copper foil.

[0014] Compared with the prior art, the beneficial effects of this utility model are:

[0015] This invention utilizes a skeleton formed by a flat glass fiber cloth, which, in conjunction with a resin filler layer containing dispersed silica powder, provides dual constraint on the thermal expansion of the resin matrix. The flat glass fiber cloth provides strong constraint in the XY directions, while its flat structure reduces interlayer gaps, providing more effective support for the Z-axis. The silica powder is uniformly distributed in the resin, forming a large number of rigid nodes, which significantly increases the path resistance of resin expansion, thereby greatly reducing the coefficient of thermal expansion in the Z-axis and effectively preventing the metallized holes from breaking. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model;

[0017] Figure 2 This is an exploded view of the present invention;

[0018] Figure 3 This is a schematic diagram of a partial cross-sectional structure of the present invention.

[0019] In the figure: 1. Copper sheet; 2. Substrate; 21. Flat glass fiber cloth; 211. Warp yarn; 212. Weft yarn; 213. Mesh; 22. Resin filler layer; 221. Silica powder. Detailed Implementation

[0020] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] Please see Figure 1-3 A low thermal expansion high-frequency copper-clad laminate includes a substrate 2 and a copper sheet 1 laminated on at least one surface of the substrate 2. The copper sheet 1 is a low-profile electrolytic copper foil or rolled copper foil. The rough copper surface has many tiny sharp corners and grooves, which are stress concentration points. When the circuit board undergoes thermal cycling, the resin and copper expand and contract due to their different coefficients of thermal expansion. These stress concentration points are prone to causing microcracks. However, the smooth copper foil using low-profile electrolytic copper foil or rolled copper foil has no obvious stress concentration points at its smooth interface. The thermal stress distribution is more uniform, which greatly reduces the risk of resin-copper foil interface delamination and improves the long-term reliability of the product.

[0024] The substrate 2 includes a flat glass fiber cloth 21 and a resin filler layer 22. The flat structure of the flat glass fiber cloth 21 reduces the interlayer gap and provides more effective support for the Z-axis. Specifically, the flat glass fiber cloth 21 is made of S-grade glass fiber cloth or NE-type glass fiber cloth. This type of glass fiber cloth has a low dielectric constant. The resin filler layer 22 is made of modified hydrocarbon resin or cyanate ester resin. The flat glass fiber cloth 21 is woven from several warp yarns 211 and several weft yarns 212 in a crisscross pattern, and several meshes 213 are formed between the warp yarns 211 and the weft yarns 212.

[0025] The resin filler layer 22 fills the pores of the mesh 213, and the resin filler layer 22 contains uniformly dispersed silica powder 221. Specifically, the particle size of the silica powder 221 ranges from 50 to 500 nm. Nano silica powder 221 is an excellent inorganic dielectric material. Combined with the low-loss resin system, it ensures that the copper clad laminate has a low and stable dielectric constant and an extremely low dielectric loss factor, meeting the requirements of high-frequency applications. The mass fraction of silica powder 221 in the resin filler layer 22 is 30-60%. The dispersion density of silica powder 221 in the resin filler layer 22 gradually increases from the flat glass fiber cloth 21 side to the copper sheet 1 side, so that the concentration of silica powder 221 is higher near the surface layer of the copper foil, thereby providing the strongest rigidity where the interfacial stress needs to be restrained the most.

[0026] During manufacturing, a resin solution is first prepared using a low-loss modified hydrocarbon resin, and spherical silica powder 221 with an average particle size of 50-500 nm, accounting for 30-60% of the total resin mass, is added as a filler. The mixture is homogeneously mixed by high-speed stirring and ultrasonic dispersion to form a resin filler layer 22. Next, a flat glass fiber cloth 21 is impregnated in the resin solution. Through coating or impregnation processes, the resin filler layer 22 is fully filled with the mesh 213 pores. Furthermore, through centrifugation, sedimentation control, and other technologies, the silica powder 221 is made into a gradient distribution in the thickness direction of the board. Finally, after drying and semi-curing stages, an adhesive sheet is formed. One or more adhesive sheets are stacked with a copper sheet 1 and pressed and cured under high temperature and high pressure to obtain a high-frequency copper-clad laminate with a low coefficient of thermal expansion.

[0027] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0028] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A low thermal expansion high-frequency copper-clad laminate, comprising a substrate (2) and a copper sheet (1) clad on at least one surface of the substrate (2), characterized in that: The substrate (2) includes a flat glass fiber cloth (21) and a resin filler layer (22). The flat glass fiber cloth (21) is woven from a plurality of warp yarns (211) and a plurality of weft yarns (212) in a crisscross pattern, and a plurality of meshes (213) are formed between the warp yarns (211) and the weft yarns (212). The resin filler layer (22) fills the meshes (213) and silica powder (221) is uniformly dispersed in the resin filler layer (22).

2. The low thermal expansion high-frequency copper-clad laminate according to claim 1, characterized in that: The flat glass fiber cloth (21) is made of S-grade glass fiber cloth or NE-type glass fiber cloth.

3. The low thermal expansion high-frequency copper-clad laminate according to claim 1, characterized in that: The resin filler layer (22) is made of modified hydrocarbon resin or cyanate ester resin.

4. The low thermal expansion high-frequency copper-clad laminate according to claim 1, characterized in that: The particle size range of the silica powder (221) is 50-500 nm.

5. The low thermal expansion high-frequency copper-clad laminate according to claim 1, characterized in that: The silica powder (221) has a mass fraction of 30-60% in the resin filler layer (22).

6. The low thermal expansion high-frequency copper-clad laminate according to claim 1, characterized in that: The dispersion density of the silica powder (221) in the resin filler layer (22) gradually increases from the flat glass fiber cloth (21) side to the copper sheet (1) side.

7. The low thermal expansion high-frequency copper-clad laminate according to claim 1, characterized in that: The copper sheet (1) is a low-profile electrolytic copper foil or a rolled copper foil.

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