Low-dielectric PTFE high-frequency copper-clad plate and preparation method thereof

Abstract

The application provides a low-dielectric PTFE high-frequency copper-clad plate and a preparation method thereof. The preparation method comprises the following steps: S1. dispersing superfine short glass fibers, silica gel and starch in deionized water, uniformly mixing, and then vacuum suction filtering to prepare a fiber felt wet blank, and drying the fiber felt wet blank at 120 DEG C to obtain a glass fiber felt; S2. desizing treating the glass fiber felt obtained in step S1 for 20-60 minutes to obtain a pretreated glass fiber felt; S3. interlacing and laminating a PTFE film and the pretreated glass fiber felt obtained in step S2, that is, one pretreated glass fiber felt obtained in step S2 is arranged between two adjacent PTFE films, one PTFE film is arranged between two adjacent pretreated glass fiber felts obtained in step S2, the uppermost and lowermost are both PTFE films, then a copper foil is arranged on the surface of the uppermost PTFE film to obtain a laminated sheet; and S4. placing the laminated sheet obtained in step S3 in a high-temperature press, pressing at 350-400 DEG C for 5-12 hours to obtain the low-dielectric PTFE high-frequency copper-clad plate. The low-dielectric PTFE high-frequency copper-clad plate provided by the application has good dielectric properties and rigidity.

Description

Technical Field

[0001] This invention relates to a copper-clad laminate, and more particularly to a low-dielectric PTFE high-frequency copper-clad laminate and its preparation method. Background Technology

[0002] Currently, there are two main manufacturing methods for fiberglass-filled PTFE high-frequency copper-clad laminates both domestically and internationally: the first method involves directly impregnating electronic-grade fiberglass cloth woven from fiberglass yarn with PTFE emulsion, followed by baking and pressing; the second method involves adding random short fiberglass fibers to the PTFE emulsion, mixing them evenly, and then applying adhesive, baking, and pressing. The first method, using fiberglass cloth directly, results in material directionality due to the warp and weft yarns, which is detrimental to high-frequency signal transmission. The second method, where short fiberglass fibers are not cross-linked within the PTFE emulsion, leads to insufficient rigidity in the material itself, making it prone to deformation. This can cause warping and curling during PCB manufacturing, resulting in poor processability.

[0003] Chinese patent application CN201510782353.6 discloses a "method for preparing PTFE copper-clad laminate," comprising the following steps: a) adhesive cloth preparation: impregnating fiberglass cloth with polytetrafluoroethylene dispersion and then drying and baking it to form an adhesive cloth; b) dielectric layer preform preparation: pre-assembling the adhesive cloth prepared in step a to form a dielectric layer preform; c) product raw material stacking preparation: combining the dielectric layer preform prepared in step b with copper foil or metal base and stacking them to form a product raw material; d) hot-pressing composite preparation of the PTFE copper-clad laminate: hot-pressing the product raw material prepared in step c under a certain vacuum degree at a certain temperature, pressure, and time to form the PTFE copper-clad laminate product. This invention belongs to the first method mentioned above, and also suffers from the problem of poor dielectric properties. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a low-dielectric PTFE high-frequency copper-clad laminate and its preparation method, wherein the low-dielectric PTFE high-frequency copper-clad laminate has good dielectric properties and rigidity.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A method for preparing a low-dielectric PTFE high-frequency copper-clad laminate includes the following steps:

[0007] S1. Disperse ultrafine short glass fibers, silica gel, and starch in deionized water, mix evenly, and then vacuum filter through a mold to form a fiber felt wet blank. Dry the fiber felt wet blank at 120℃ to obtain fiberglass felt. The role of silica gel is mainly to make each ultrafine short glass fiber overlap and form a network interwoven structure. The role of starch is to wrap the ultrafine short glass fibers and protect them from frictional breakage during production. The fiberglass felt is formed by the mechanical interlocking effect of the interlacing between the original fibers and a small amount of adhesive. The density is 5-20 g / m², the thickness is 0.01-0.05 mm, and it has the advantages of erosion resistance, good moldability, high mechanical strength, and easy removal of air bubbles.

[0008] S2. Desizing the fiberglass mat obtained in step S1 for 20-60 minutes to obtain pretreated fiberglass mat; this step is to remove the starch slurry inside the fiberglass mat through desizing to obtain pure fiberglass mat without slurry.

[0009] S3. The PTFE membrane and the pretreated glass fiber mat obtained in step S2 are stacked alternately, that is, there is a pretreated glass fiber mat obtained in step S2 between two adjacent PTFE membranes, and there is a PTFE membrane between two adjacent pretreated glass fiber mats obtained in step S2. The top and bottom are both PTFE membranes. Then, a copper foil is covered on the surface of the top PTFE membrane to obtain the laminated sheet.

[0010] S4. Place the laminated sheet obtained in step S3 in a high-temperature press and press it at 350-400℃ for 5-12 hours to obtain a low-dielectric PTFE high-frequency copper-clad laminate.

[0011] Furthermore, in step S1 of this invention, the diameter of the ultrafine short glass fiber is 3-15 μm and the length is 1-5 mm. The selection of 3-15 μm and 1-5 mm ultrafine short glass fibers ensures sufficient penetration and tight bonding with PTFE resin during the high-temperature pressing process, preventing interfacial gaps.

[0012] Furthermore, in step S1 of the present invention, the silicone is polydimethylsiloxane.

[0013] Furthermore, in step S1 of the present invention, the weight ratio of ultrafine short glass fiber, silica gel, starch and deionized water is (10-25):(2-10):(3-10):(55-85).

[0014] Furthermore, in step S2 of the present invention, the temperature of the desizing treatment is 350-450℃.

[0015] Furthermore, in step S4 of the present invention, the pressure during pressing is 3-9 MPa.

[0016] The present invention also provides a low-dielectric PTFE high-frequency copper-clad laminate obtained by the above preparation method.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The low dielectric PTFE high frequency copper-clad laminate signal line provided by the present invention transmits in the horizontal direction. The ultra-fine short glass fibers in the glass fiber felt are randomly distributed. Compared with the woven glass fiber cloth, the glass fiber felt used in the present invention has no directionality, which ensures the isotropic characteristics of signal transmission.

[0019] (2) In the structure of the board, the glass fiber mat is evenly distributed in each layer. The mechanical interlocking effect between the ultra-fine short glass fibers greatly increases the rigidity of the board, which can effectively avoid the warping and curling of the board due to insufficient rigidity during PCB processing.

[0020] (3) In the preparation method of the present invention, the slurry and adhesive inside the glass fiber mat need to be removed before use to ensure the dielectric loss of the board. However, if all the slurry is removed, the glass fiber mat will become very brittle. Therefore, 1-5% of the slurry needs to be retained to ensure the strength of the glass fiber mat. Accordingly, the deslurry process conditions are particularly important. In this regard, the present invention preferably uses a deslurry temperature of 350-450℃ and a deslurry time of 20-60 minutes, which can meet the aforementioned requirements.

[0021] (4) During the high-temperature pressing process of the preparation method of the present invention, PTFE will melt and flow, and uniformly penetrate into the interior of the glass fiber felt and tightly bond with the glass fiber. Through sufficient melting, flow and penetration, the glass fiber felt can achieve a completely seamless bond with PTFE, thereby ensuring the performance of the board. Detailed Implementation

[0022] The present invention will now be described in detail with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0023] Example 1:

[0024] Prepare a low-dielectric PTFE high-frequency copper-clad laminate according to the following steps:

[0025] S1. In a weight ratio of 15:5:5:75, ultrafine short glass fibers with a diameter of 10μm and a length of 4mm, polydimethylsiloxane, and starch are dispersed in deionized water, mixed evenly, and then vacuum filtered through a mold to prepare a fiber felt wet blank. The fiber felt wet blank is dried at 120℃ to obtain glass fiber felt.

[0026] S2. Desizing the fiberglass mat obtained in step S1 at 400°C for 40 minutes to obtain pretreated fiberglass mat;

[0027] S3. Four PTFE films and three pretreated fiberglass mats obtained in step S2 are stacked alternately, that is, one pretreated fiberglass mat obtained in step S2 is placed between two adjacent PTFE films, and one PTFE film is placed between two adjacent pretreated fiberglass mats obtained in step S2. The top and bottom are both PTFE films. Then, a copper foil is covered on the surface of the top PTFE film to obtain the laminated sheet.

[0028] S4. Place the laminated sheet obtained in step S3 in a high-temperature press and press it at 5MPa and 360℃ for 8 hours to obtain a low-dielectric PTFE high-frequency copper-clad laminate.

[0029] Example 2

[0030] Prepare a low-dielectric PTFE high-frequency copper-clad laminate according to the following steps:

[0031] S1. In a weight ratio of 10:2:3:55, ultrafine short glass fibers with a diameter of 3μm and a length of 1mm, polydimethylsiloxane, and starch are dispersed in deionized water, mixed evenly, and then vacuum filtered through a mold to prepare a fiber felt wet blank. The fiber felt wet blank is dried at 120℃ to obtain glass fiber felt.

[0032] S2. Desizing the fiberglass mat obtained in step S1 at 350°C for 60 minutes to obtain pretreated fiberglass mat;

[0033] S3. Four PTFE films and three pretreated fiberglass mats obtained in step S2 are stacked alternately, that is, one pretreated fiberglass mat obtained in step S2 is placed between two adjacent PTFE films, and one PTFE film is placed between two adjacent pretreated fiberglass mats obtained in step S2. The top and bottom are both PTFE films. Then, a copper foil is covered on the surface of the top PTFE film to obtain the laminated sheet.

[0034] S4. Place the laminated sheet obtained in step S3 in a high-temperature press and press it at 3MPa and 400℃ for 5 hours to obtain a low-dielectric PTFE high-frequency copper-clad laminate.

[0035] Example 3

[0036] Prepare a low-dielectric PTFE high-frequency copper-clad laminate according to the following steps:

[0037] S1. In a weight ratio of 25:10:10:85, ultrafine short glass fibers with a diameter of 15μm and a length of 5mm, polydimethylsiloxane, and starch are dispersed in deionized water, mixed evenly, and then vacuum filtered through a mold to prepare a fiber felt wet blank. The fiber felt wet blank is dried at 120℃ to obtain glass fiber felt.

[0038] S2. Desizing the fiberglass mat obtained in step S1 at 450°C for 20 minutes to obtain pretreated fiberglass mat;

[0039] S3. Six PTFE films and five pretreated fiberglass mats obtained in step S2 are stacked alternately, that is, one pretreated fiberglass mat obtained in step S2 is placed between two adjacent PTFE films, and one PTFE film is placed between two adjacent pretreated fiberglass mats obtained in step S2. The top and bottom are both PTFE films. Then, a copper foil is covered on the surface of the top PTFE film to obtain the laminated sheet.

[0040] S4. Place the laminated sheet obtained in step S3 in a high-temperature press and press it at 9MPa and 350℃ for 12 hours to obtain a low-dielectric PTFE high-frequency copper-clad laminate.

[0041] Example 4

[0042] Prepare a low-dielectric PTFE high-frequency copper-clad laminate according to the following steps:

[0043] S1. In accordance with the weight ratio of 21:9:6:80, ultrafine short glass fibers with a diameter of 10μm and a length of 2mm, polydimethylsiloxane, and starch are dispersed in deionized water, mixed evenly, and then vacuum filtered through a mold to prepare a fiber felt wet blank. The fiber felt wet blank is dried at 120℃ to obtain glass fiber felt.

[0044] S2. Desizing the fiberglass mat obtained in step S1 at 420°C for 30 minutes to obtain pretreated fiberglass mat;

[0045] S3. Six PTFE films and five pretreated fiberglass mats obtained in step S2 are stacked alternately, that is, one pretreated fiberglass mat obtained in step S2 is placed between two adjacent PTFE films, and one PTFE film is placed between two adjacent pretreated fiberglass mats obtained in step S2. The top and bottom are both PTFE films. Then, a copper foil is covered on the surface of the top PTFE film to obtain the laminated sheet.

[0046] S4. Place the laminated sheet obtained in step S3 in a high-temperature press and press it at 6MPa and 380℃ for 6 hours to obtain a low-dielectric PTFE high-frequency copper-clad laminate.

[0047] Comparative Example

[0048] Unlike Example 1, S2 is not included. In step S3, the pretreated fiberglass mat obtained in step S2 is replaced with the fiberglass mat obtained in step S1, that is, the fiberglass mat is not desized before use.

[0049] Experimental Example: Performance Testing

[0050] The low-dielectric PTFE high-frequency copper-clad laminates prepared in Examples 1-4 and Comparative Example 1 were subjected to performance tests, and the test results are shown in Table 1.

[0051] The dielectric properties were tested using a vector network analyzer, with the testing standard referencing the IPC-TM-650 standard. The test method was the split resonant cavity method, and the test conditions were room temperature and a resonant frequency of 10 GHz.

[0052] The test standard for thermal shock performance testing refers to GB / T 15727-1995, and the test conditions are 288℃, 10s, 6 times.

[0053] The test instrument for peel performance testing was a copper foil peel strength tester. The test standard referred to IPC-TM-650. The test conditions were a speed of 25 mm / min, a span of 50 mm, and a sample size of 90 mm × 120 mm.

[0054] The test standard for warpage testing is based on IPC-TM-650.

[0055]

[0056] Table 1

[0057] As shown in Table 1, Examples 1-4 exhibited good dielectric properties, thermal shock resistance, and peel strength, with minimal warpage, indicating good rigidity. The preparation steps of the comparative example differed from Example 1. Compared to Example 1, the comparative example showed similar thermal shock resistance, peel strength, and warpage, but its dielectric properties were significantly inferior to Example 1. This demonstrates that the desizing treatment employed in this invention effectively improves the dielectric properties of the copper-clad laminate.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing a low-dielectric PTFE high-frequency copper-clad laminate, characterized in that: Includes the following steps: S1. Disperse ultrafine short glass fibers, silica gel, and starch in deionized water, mix evenly, and then vacuum filter through a mold to prepare a fiber felt wet blank. Dry the fiber felt wet blank at 120℃ to obtain glass fiber felt; the diameter of the ultrafine short glass fibers is 3-15μm and the length is 1-5mm, the silica gel is polydimethylsiloxane, and the weight ratio of ultrafine short glass fibers, silica gel, starch, and deionized water is (10-25):(2-10):(3-10):(55-85); S2. Desizing the fiberglass mat obtained in step S1 for 20-60 minutes to obtain pretreated fiberglass mat. The temperature of the desizing treatment is 350-450℃. S3. The PTFE membrane and the pretreated glass fiber mat obtained in step S2 are stacked alternately, that is, there is a pretreated glass fiber mat obtained in step S2 between two adjacent PTFE membranes, and there is a PTFE membrane between two adjacent pretreated glass fiber mats obtained in step S2. The top and bottom are both PTFE membranes. Then, a copper foil is covered on the surface of the top PTFE membrane to obtain the laminated sheet. S4. Place the laminated sheet obtained in step S3 in a high-temperature press and press it at 350-400℃ for 5-12 hours to obtain a low-dielectric PTFE high-frequency copper-clad laminate.

2. The method for preparing a low-dielectric PTFE high-frequency copper-clad laminate according to claim 1, characterized in that: In step S4, the pressure during pressing is 3-9 MPa.

3. The low-dielectric PTFE high-frequency copper-clad laminate obtained by the preparation method according to any one of claims 1 to 2.

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