Polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low-loss high-frequency substrate and preparation method thereof

Abstract

The invention relates to the technical field of base materials for high-frequency and high-speed circuit boards, in particular to a polytetrafluoroethylene glass fabric ceramic dielectric constant low-loss high-frequency substrate and a preparation method. The polytetrafluoroethylene glass fabric ceramic dielectric constant low-loss high-frequency substrate comprises a plurality of prefabricated sheet layers and two copper foil layers, the slurry is prepared by mixing a PTFE emulsion, silicon oxide, titanium oxide, a modifier, a dispersant and a thickener, the dielectric constant of the PTFE emulsion is about 2.1, the loss of the PTFE emulsion is 0.0009, the emulsion in the technical scheme is prepared by mixing the PTFE emulsion, the silicon oxide, the titanium oxide, the modifier, the dispersant and the thickener, the dielectric constant of the silicon oxide is about 6, the loss of the silicon oxide is about 0.0015, and the loss of the silicon oxide is about 0.0015. The dielectric constant of titanium oxide is about 60, and the loss is about 0.0025, so that the dielectric constant is improved and the loss value is reduced, and therefore, the high-frequency substrate provided by the technical scheme has the advantages of small dielectric constant tolerance, low loss, good frequency stability, better peeling strength, low thermal expansion coefficient and good reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of substrates for high-frequency and high-speed circuit boards, and particularly relates to a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate and a preparation method thereof. Background Art

[0002] For high-frequency and high-speed circuit application scenarios such as microwave and radio frequency circuits, base station antennas, wireless communication devices, and automotive electronics, boards with stable dielectric constants and low losses are required. In the prior art, FR4 boards are mostly used.

[0003] However, the dielectric constant of conventional FR4 boards is usually between 4.5 ± 0.03, and the dielectric constant is unstable, resulting in unstable frequencies. Moreover, the loss of conventional FR4 boards > 0.01, and the large loss value leads to signal delay and increased loss, which is not conducive to the transmission of high-frequency microwave signals. Summary of the Invention

[0004] The purpose of the present invention is to provide a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate and a preparation method thereof, to solve the problems that the dielectric constant of conventional FR4 boards is usually between 4.5 ± 0.03, the dielectric constant is unstable, resulting in unstable frequencies, and the loss of conventional FR4 boards > 0.01, the large loss value leads to signal delay and increased loss, which is not conducive to the transmission of high-frequency microwave signals.

[0005] To achieve the above purpose, the present invention provides a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate. The polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate includes multiple prefabricated sheet layers and two copper foil layers. Multiple prefabricated sheet layers are laminated between the two copper foil layers. Each prefabricated sheet layer is prepared by impregnating fiberglass cloth with a slurry. The slurry is prepared by mixing PTFE emulsion, ceramic material, modifier, dispersant, and thickener. The ceramic material is composed of silicon oxide and titanium oxide.

[0006] The present invention also provides a preparation method of a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate for preparing the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate as described above, including the following steps:

[0007] Sequentially add the PTFE emulsion, the modifier, the dispersant, and the thickener to deionized water and mechanically stir, and respectively add silicon oxide and titanium oxide during the stirring process to obtain the slurry;

[0008] After adding the slurry to the impregnating machine, pass the fiberglass cloth through the impregnating machine to impregnate the slurry, and then obtain the prefabricated sheet layer after drying, sintering, and cutting;

[0009] After cutting the prefabricated sheet layer and the copper foil layer as needed, stack multiple prefabricated sheet layers, and then stack two copper foil layers on the upper and lower surfaces of the multiple prefabricated sheet layers respectively to obtain a semi-finished sheet;

[0010] Use a vacuum press to perform vacuum pressing on the semi-finished sheet to obtain the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate.

[0011] Among them, in the step of "after adding the slurry to the impregnating machine, passing the fiberglass cloth through the impregnating machine to impregnate the slurry, and then obtaining the prefabricated sheet layer after drying, sintering and cutting", when impregnating the fiberglass cloth with the slurry, the impregnating speed of the pinch roller gap of the impregnating machine is 1.0 - 2.0M / min.

[0012] Among them, in the step of "after adding the slurry to the impregnating machine, passing the fiberglass cloth through the impregnating machine to impregnate the slurry, and then obtaining the prefabricated sheet layer after drying, sintering and cutting", when drying and sintering the impregnated fiberglass cloth, the temperature is 380 - 420°C.

[0013] Among them, in the step of "using a vacuum press to perform vacuum pressing on the semi-finished sheet to obtain the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate", the pressing temperature of the vacuum press is 380 - 400°C.

[0014] Among them, in the step of "using a vacuum press to perform vacuum pressing on the semi-finished sheet to obtain the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate", the pressure of the vacuum press is 2.0 - 3.5MPA.

[0015] Among them, in the step of "using a vacuum press to perform vacuum pressing on the semi-finished sheet to obtain the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate", the pressing time of the vacuum press is 6 - 8 hours.

[0016] A polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate and preparation method thereof according to the present invention include multiple prefabricated sheet layers and two copper foil layers. Each of the prefabricated sheet layers is prepared by impregnating fiberglass cloth with a slurry. The slurry is prepared by mixing PTFE emulsion, ceramic materials, modifiers, dispersants, and thickeners. The ceramic materials are composed of silicon oxide and titanium oxide. The PTFE emulsion is used as the impregnating resin. The dielectric constant of the PTFE emulsion is about 2.1, and the loss is 0.0009. And in the technical solution of the present invention, the emulsion is prepared by mixing PTFE emulsion, silicon oxide, titanium oxide, modifiers, dispersants, and thickeners. The dielectric constant of silicon oxide is about 6, and the loss is about 0.0015. The dielectric constant of titanium oxide is about 60, and the loss is about 0.0025. To improve the dielectric constant and reduce the loss value. Therefore, the high-frequency substrate proposed by the technical solution of the present invention has the advantages of small dielectric constant tolerance, low loss, good frequency stability, better peel strength resistance, low coefficient of thermal expansion, and good reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 is a schematic structural diagram of a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate provided by the present invention.

[0019] Figure 2 is a flowchart of the steps of a preparation method of a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate provided by the present invention.

[0020] Figure 3 is a flowchart of the steps of a preparation method of a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate with a dielectric constant of 3.0 in Embodiment 1 provided by the present invention.

[0021] Figure 4 is a flowchart of the steps of a preparation method of a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate with a dielectric constant of 3.5 in Embodiment 2 provided by the present invention.

[0022] Figure 5 is a flowchart of the steps of a preparation method of a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate with a dielectric constant of 6.15 in Embodiment 3 provided by the present invention.

[0023] 101 - Prefabricated sheet layer, 102 - Copper foil layer, 103 - Slurry. Detailed Embodiment

[0024] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0025] Please refer to Figure 1 , the present invention provides a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate. The polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate includes multiple prefabricated sheet layers 101 and two copper foil layers 102. Multiple prefabricated sheet layers 101 are laminated between the two copper foil layers 102. Each prefabricated sheet layer 101 is prepared by impregnating a fiberglass cloth (the fiberglass cloth used in this technical solution is a 106-type electronic-grade fiberglass cloth) with a slurry 103. The slurry 103 is prepared by mixing a PTFE emulsion, a ceramic material, a modifier, a dispersant, and a thickener. The ceramic material is composed of silicon oxide and titanium oxide.

[0026] In this embodiment, the PTFE emulsion is used as the impregnating resin. The dielectric constant of the PTFE emulsion is about 2.1, and the loss is 0.0009. And the type of the fiberglass cloth is fixed, and a 106-type electronic-grade fiberglass cloth is used. The dielectric constant of the fiberglass cloth is about 6.5, and the loss is 0.005. After impregnating the slurry 103, the prefabricated sheet layer 101 is obtained. Laminating multiple prefabricated sheet layers 101 can meet the requirements of various thicknesses of customers. And the emulsion in this technical solution is prepared by mixing a PTFE emulsion, silicon oxide, titanium oxide, a modifier, a dispersant, and a thickener. The dielectric constant of silicon oxide is about 6, and the loss is about 0.0015. The dielectric constant of titanium oxide is about 60, and the loss is about 0.0025, so as to improve the dielectric constant and reduce the loss value. Therefore, the high-frequency substrate proposed by this technical solution has the advantages of small dielectric constant tolerance, low loss, good frequency stability, better peel strength, low thermal expansion coefficient, and good reliability. The specific performance of the high-frequency substrate prepared by this technical solution is as follows:

[0027] DK: 4.5 ± 0.09 (10 GHz); DF: ≤ 0.002 (10 GHz); Peel strength (1 OZ): > 1.2 N / mm; Thermal expansion coefficient (X / Y / Z) ≤ 20 / 20 / 60; Water absorption: < 0.1%.

[0028] Please refer to Figure 2 , the present invention also provides a preparation method for a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate, which is used to prepare the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate as described above, and includes the following steps:

[0029] S1: Sequentially add the PTFE emulsion, the modifier, the dispersant, and the thickener into deionized water and mechanically stir, and respectively add silicon oxide and titanium oxide during the stirring process to obtain the slurry 103;

[0030] S2: After adding the slurry 103 to the impregnating machine, pass the glass fiber cloth through the impregnating machine to impregnate the slurry 103, and after drying, sintering, and cutting, obtain the prefabricated sheet layer 101;

[0031] S3: After cutting the prefabricated sheet layer 101 and the copper foil layer 102 as required, stack multiple prefabricated sheet layers 101, and respectively stack two copper foil layers 102 on the upper and lower surfaces of multiple prefabricated sheet layers 101 to obtain a semi-finished board;

[0032] S4: Use a vacuum press to perform vacuum pressing on the semi-finished board to obtain the polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low-loss high-frequency substrate.

[0033] In this embodiment, first, sequentially add the PTFE emulsion, the modifier, the dispersant, and the thickener into deionized water and mechanically stir, and respectively add silicon oxide and titanium oxide during the stirring process to obtain the slurry 103. Then, after adding the slurry 103 to the impregnating machine, pass the glass fiber cloth through the impregnating machine to impregnate the slurry 103, and after drying, sintering, and cutting, obtain the prefabricated sheet layer 101. Then, after cutting the prefabricated sheet layer 101 and the copper foil layer 102 as required, stack multiple prefabricated sheet layers 101, and respectively stack two copper foil layers 102 on the upper and lower surfaces of multiple prefabricated sheet layers 101 to obtain a semi-finished board. Finally, use a vacuum press to perform vacuum pressing on the semi-finished board to obtain the polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low-loss high-frequency substrate.

[0034] Further, in the step "After adding the slurry 103 to the impregnating machine, pass the glass fiber cloth through the impregnating machine to impregnate the slurry 103, and after drying, sintering, and cutting, obtain the prefabricated sheet layer 101", when impregnating the glass fiber cloth with the slurry 103, the impregnating speed of the pinch roll gap of the impregnating machine is 1.0 - 2.0 M / min.

[0035] Further, in the step "After adding the slurry 103 to the impregnating machine, pass the glass fiber cloth through the impregnating machine to impregnate the slurry 103, and after drying, sintering, and cutting, obtain the prefabricated sheet layer 101", when drying and sintering the impregnated glass fiber cloth, the temperature is 380 - 420 °C.

[0036] Further, in the step of "using a vacuum press to vacuum press the semi-finished sheet to obtain the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate", the pressing temperature of the vacuum press is 380-400 °C.

[0037] Further, in the step of "using a vacuum press to vacuum press the semi-finished sheet to obtain the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate", the pressure of the vacuum press is 2.0-3.5 MPA.

[0038] Further, in the step of "using a vacuum press to vacuum press the semi-finished sheet to obtain the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate", the pressing time of the vacuum press is 6-8 hours.

[0039] Example 1:

[0040] Please refer to Figure 3 , the present invention also provides a method for preparing a polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate for preparing the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate (dielectric constant is 3.0) as described above, including the following steps:

[0041] S101: Add 42 KG of the 60% concentration PTFE emulsion, the modifier, the dispersant, and the thickener to 30 KG of deionized water in sequence and mechanically stir, and add 28.5 KG of silicon oxide and 2 KG of titanium oxide respectively during the stirring process to obtain the slurry 103;

[0042] S102: Add the slurry 103 to an impregnating machine, impregnate the fiberglass cloth with the slurry 103 at a nip gap impregnating speed of 1.0 M / min through the impregnating machine, and then perform drying and sintering at a temperature of 380 °C, and cut to obtain the prefabricated sheet layer 101;

[0043] S103: Cut the prefabricated sheet layer 101 and the copper foil layer 102 as required, stack multiple prefabricated sheet layers 101, and stack two copper foil layers 102 on the upper and lower surfaces of multiple prefabricated sheet layers 101 respectively to obtain a semi-finished sheet;

[0044] S104: Use a vacuum press to vacuum press the semi-finished sheet under the conditions of a pressing temperature of 380 °C and a pressure of 2.0 MPA to obtain the polytetrafluoroethylene fiberglass cloth ceramic dielectric constant low-loss high-frequency substrate with a dielectric constant of 3.0.

[0045] Example 2:

[0046] Please refer to Figure 4, the present invention also provides a method for preparing a polytetrafluoroethylene fiberglass cloth ceramic dielectric low-loss high-frequency substrate for preparing the polytetrafluoroethylene fiberglass cloth ceramic dielectric low-loss high-frequency substrate (dielectric constant of 3.5) as described above, including the following steps:

[0047] S201: Sequentially add 42KG of the 60% concentration PTFE emulsion, the modifier, the dispersant, and the thickener to 30KG of deionized water and mechanically stir, and respectively add 22.5KG of silicon oxide and 8KG of titanium oxide during the stirring process to obtain the slurry 103;

[0048] S202: Add the slurry 103 to an impregnating machine, and impregnate the fiberglass cloth with the slurry 103 through the impregnating machine at a nip impregnation speed of 1.5M / min, and then perform drying and sintering at a temperature of 400°C, and cut to obtain the prefabricated sheet layer 101;

[0049] S203: After cutting the prefabricated sheet layer 101 and the copper foil layer 102 as required, stack multiple prefabricated sheet layers 101, and stack two copper foil layers 102 on the upper and lower surfaces of multiple prefabricated sheet layers 101 respectively to obtain a semi-finished sheet;

[0050] S204: Use a vacuum press to perform vacuum pressing on the semi-finished sheet under the conditions of a pressing temperature of 400°C and a pressure of 2.75MPA to obtain the polytetrafluoroethylene fiberglass cloth ceramic dielectric low-loss high-frequency substrate with a dielectric constant of 3.5.

[0051] Example 3:

[0052] Please refer to Figure 5 , the present invention also provides a method for preparing a polytetrafluoroethylene fiberglass cloth ceramic dielectric low-loss high-frequency substrate for preparing the polytetrafluoroethylene fiberglass cloth ceramic dielectric low-loss high-frequency substrate (dielectric constant of 6.15) as described above, including the following steps:

[0053] S301: Sequentially add 42KG of the 60% concentration PTFE emulsion, the modifier, the dispersant, and the thickener to 30KG of deionized water and mechanically stir, and respectively add 4.3KG of silicon oxide and 26KG of titanium oxide during the stirring process to obtain the slurry 103;

[0054] S302: Add the slurry 103 to an impregnating machine, and impregnate the fiberglass cloth with the slurry 103 through the impregnating machine at a nip impregnation speed of 2.0M / min, and then perform drying and sintering at a temperature of 420°C, and cut to obtain the prefabricated sheet layer 101;

[0055] S303: After cutting the prefabricated sheet layer 101 and the copper foil layer 102 as needed, after laminating multiple prefabricated sheet layers 101, laminate two copper foil layers 102 on the upper and lower surfaces of the multiple prefabricated sheet layers 101 respectively to obtain a semi-finished sheet;

[0056] S304: Use a vacuum press to perform vacuum pressing on the semi-finished sheet under the conditions of a pressing temperature of 420 °C and a pressure of 3.5 MPA to obtain the polytetrafluoroethylene fiberglass cloth ceramic dielectric low-loss high-frequency substrate with a dielectric constant of 6.15.

[0057] The above-disclosed is only a preferred embodiment of the present invention. Of course, the scope of the rights of the present invention cannot be limited by this. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.

Claims

1. A polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low loss high frequency substrate, characterized in that: It comprises a plurality of prefabricated sheets and two copper foil layers, wherein a plurality of the prefabricated sheets are stacked between the two copper foil layers, and each of the prefabricated sheets is prepared by impregnating glass fiber cloth with slurry, wherein the slurry is prepared by mixing PTFE emulsion, ceramic material, modifier, dispersant and thickener, and the ceramic material is composed of silicon oxide and titanium oxide.

2. A method for preparing a polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low loss high frequency substrate, used to prepare the polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low loss high frequency substrate as claimed in claim 1, characterized in that: The steps include: The PTFE emulsion, the modifier, the dispersant and the thickener are sequentially added to deionized water and mechanically stirred, and silicon oxide and titanium oxide are respectively added during the stirring process to obtain the slurry; After the slurry is added to the dipping machine, the glass fiber cloth is impregnated with the slurry through the dipping machine, and then dried, sintered and cut to obtain the prefabricated sheet layer; After cutting the prefabricated sheet layer and the copper foil layer as needed, after stacking a plurality of the prefabricated sheets, two copper foil layers are stacked on the upper and lower surfaces of the plurality of the prefabricated sheets, respectively, to obtain a semi-finished plate; The semi-finished plate is vacuum pressed by a vacuum press to obtain the polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low-loss high-frequency substrate.

3. The method for preparing the polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low loss high frequency substrate according to claim 2, characterized in that: In the step of "adding the slurry to the dipping machine, dipping the glass fiber cloth into the slurry through the dipping machine, drying, sintering and cutting to obtain the prefabricated sheet layer", when dipping the glass fiber cloth into the slurry, the dipping speed of the clamping roller gap of the dipping machine is 1.0-2.0 M / min.

4. The polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low loss high frequency substrate and preparation method as claimed in claim 3, characterized in that: In the step of "adding the slurry to the impregnation machine, impregnating the glass fiber cloth with the slurry through the impregnation machine, drying, sintering and cutting to obtain the prefabricated sheet layer", the temperature of drying and sintering the impregnated glass fiber cloth is 380-420°C.

5. The polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low loss high frequency substrate and preparation method as claimed in claim 4, characterized in that: In the step of "using a vacuum press to vacuum press the semi-finished plate to obtain the polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low-loss high-frequency substrate", the pressing temperature of the vacuum press is 380-400°C.

6. The polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low loss high frequency substrate and preparation method as claimed in claim 5, characterized in that: In the step of "using a vacuum press to vacuum press the semi-finished plate to obtain the polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low-loss high-frequency substrate", the pressure of the vacuum press is 2.0-3.5MPA.

7. The polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low loss high frequency substrate and preparation method as claimed in claim 6, characterized in that: In the step of "using a vacuum press to vacuum press the semi-finished plate to obtain the polytetrafluoroethylene glass fiber cloth ceramic dielectric constant low loss high frequency substrate", the pressing time of the vacuum press is 6-8 hours.

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