WO2020151052A1 - 一种低插损高频导热基板及其应用 - Google Patents

一种低插损高频导热基板及其应用 Download PDF

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Publication number
WO2020151052A1
WO2020151052A1 PCT/CN2019/077164 CN2019077164W WO2020151052A1 WO 2020151052 A1 WO2020151052 A1 WO 2020151052A1 CN 2019077164 W CN2019077164 W CN 2019077164W WO 2020151052 A1 WO2020151052 A1 WO 2020151052A1
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low
insertion loss
layer
frequency
copper foil
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PCT/CN2019/077164
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English (en)
French (fr)
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颜善银
许永静
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广东生益科技股份有限公司
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate
    • H05K1/0313—Organic insulating material

Definitions

  • the invention belongs to the technical field of electronic materials, and relates to a low-insertion loss high-frequency heat-conducting substrate and its application.
  • PCBs printed circuit boards
  • the space for components to be mounted and installed on the PCB has been greatly reduced.
  • the power requirements of the complete electronic products on the power components are getting higher and smaller. Space and high power inevitably produce more heat accumulation.
  • the working frequency of electronic equipment is getting higher and higher, and the heat generation is increasing.
  • the integration of a large number of powerful functions into smaller components drives the printed boards to become high-density, and at the same time the development of high-frequency signal transmission or high-speed digitalization, these two factors drive the working temperature of the printed boards to rise sharply . If the accumulated heat cannot be discharged in time, the working temperature of the equipment will rise.
  • Passive components are the basic components of every electronic device and occupy a large amount of surface area of the printed board.
  • small-sized passive components such as 0402 and 0201
  • the technology of burying passive components in a multilayer board can overcome these problems and can be widely used in the manufacture of high-end products (such as mobile phones).
  • manufacturers and assemblers face many challenges in the manufacturing, assembly, inspection, operation, and cost control of such printed boards. As the number of solder joints is reduced, the embedded passive components are more reliable.
  • the embedded components increase the line density and improve the electrical performance and functions of electronic equipment.
  • embedded passive components have many advantages, there are still some problems, including fracture delamination and the stability of various embedded components. Because embedded components usually require a multi-layer stack structure design, and the CTE mismatch of different materials will cause greater thermal stress. Unlike discrete components, defective embedded components cannot be replaced, which means that even a small component will cause the entire circuit board to be scrapped. Therefore, maintaining the long-term stability and reliability of components is the focus of manufacturers using this technology.
  • the curing temperature of PTF resistor paste on the printed circuit board should not exceed 180°C, but some manufacturers can provide resistor paste with curing temperature up to 220°C.
  • the resistance range of resistance paste and resistance paste is much larger than that of thin film resistance materials, but the resistance tolerance is relatively large and the stability is limited.
  • the oxide layer between the interface of the polymer and the copper layer will cause the resistance deviation, and it is more prone to delamination and fracture caused by CTE mismatch.
  • thin-film resistors greatly reduces the lead-in and lead-out lines related to resistance elements, and is expected to match all signal lines. It is extremely critical in high-frequency transmission. The inductance is extremely low (less than nanohenry), and the surface electromagnetic is greatly reduced. Interference (EMI). (3) Improve mechanical properties. Thin-film resistors will not be affected by shock and vibration like leaded or surface-mounted resistor components; it also avoids the assembly problems of surface-mounted resistors caused by moisture and dust. (4) Improve reliability. The number of solder joints has been greatly reduced, and many applications have shown that its long-term reliability is excellent. (5) Reduce costs. The application of thin film resistors reduces the amount of separation resistors.
  • the purpose of the present invention is to provide a thermally conductive substrate and its application, in particular to provide a low-insertion loss high-frequency thermally conductive substrate and its application, the thermally conductive substrate has higher thermal conductivity, peeling Strength and integration, and with low dielectric constant, dielectric loss and insertion loss, it can meet the requirements of high frequency and high thermal conductivity electronic circuit substrates for low dielectric constant, low dielectric loss, low insertion loss, high thermal conductivity, high Reliability and other comprehensive performance requirements, so it can be used as a circuit board in electronic products.
  • One of the objectives of the present invention is to provide a low-insertion loss high-frequency thermal conductive substrate, which includes the following layers combined together from top to bottom:
  • the first resin layer with a thickness of 2-20 ⁇ m;
  • the second resin layer with a thickness of 2-20 ⁇ m;
  • the second low profile copper foil layer with roughness Rz ⁇ 5 ⁇ m is the second low profile copper foil layer with roughness Rz ⁇ 5 ⁇ m.
  • the low insertion loss and high thermal conductivity substrate of the present invention has a thermal conductivity of 0.5W/mK ⁇ 1.5W/mK, an insertion loss lower than -0.25dB/5inch (2GHz) and lower than -0.51dB/5inch (5GHz) , Can meet the requirements of the use of high-frequency substrates; it has lower insertion loss, which can further reduce the heat generated by the high-frequency substrate; the thin film resistance layer is added to the substrate to make the prepared substrate have a higher degree of integration, which can further improve the substrate reliability.
  • the roughness Rz of the first low-profile copper foil layer is less than or equal to 5 ⁇ m, such as 0.1 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, etc. .
  • the roughness Rz of the second low-profile copper foil layer is less than or equal to 5 ⁇ m, such as 0.1 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, etc. .
  • the roughness of the first low-profile copper foil layer and the roughness of the second copper foil layer are the same.
  • the purpose of adopting the first low-profile copper foil layer and the second low-profile copper foil layer is to reduce the insertion loss of the substrate.
  • the lower the roughness of the copper foil the lower the insertion loss of the substrate; If the roughness of the copper foil layer and the second copper foil layer is too high, the insertion loss of the substrate is too high, which affects the service life of the substrate.
  • the thickness of the thin film resistance layer is 0.1-1.0 ⁇ m, for example, 0.1 ⁇ m, 0.2 ⁇ m, 0.3 ⁇ m, 0.4 ⁇ m, 0.5 ⁇ m, 0.6 ⁇ m, 0.7 ⁇ m, 0.8 ⁇ m, 0.9 ⁇ m, 1.0 ⁇ m, etc.
  • the thin film resistance layer is to improve the integration degree of the substrate, and to embed the resistance in the substrate, and ultimately improve the reliability of the substrate.
  • the thickness of the first resin layer is 2-20 ⁇ m, for example, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m , 18 ⁇ m, 19 ⁇ m, 20 ⁇ m, etc.
  • the thickness of the second resin layer is 2-20 ⁇ m, such as 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m , 18 ⁇ m, 19 ⁇ m, 20 ⁇ m, etc.
  • the thickness of the first resin layer and the second resin layer are the same.
  • the first resin layer and the second resin layer are to improve the peeling strength of the substrate dielectric layer and the copper foil, because the roughness of the copper foil is relatively low, and the bonding force with the dielectric layer is relatively low, so it needs to be on the copper foil Apply a layer of resin to improve the peel strength.
  • the thickness of the resin layer selected in the present invention is 2-20 ⁇ m, and the prepared substrate has better peel strength, dielectric properties and thermal conductivity; when the thickness of the resin layer is less than 2 ⁇ m, the prepared substrate cannot achieve improved peel strength Purpose: When the thickness of the resin layer is greater than 20 ⁇ m, it will affect the dielectric properties of the substrate, because the dielectric constant of the resin layer is relatively low, if the resin layer is thicker, the dielectric constant of the substrate will be significantly reduced; in addition, the resin layer The thermal conductivity is also relatively low. If the resin layer is thicker, the thermal conductivity of the substrate will also decrease.
  • the dielectric constant of the high-frequency thermal conductive adhesive sheet layer of the present invention is lower than 3.8 (10GHz, SPDR), for example, the dielectric constant can be 3.0, 3.2, 3.5, 3.8, etc.; the dielectric loss is less than 0.0040 (10GHz, SPDR) , For example, 0.0012, 0.0015, 0.0018, 0.0020, 0.0022, 0.0025, 0.0028, 0.0030, 0.0032, 0.0035, 0.0038, 0.0039, etc.
  • the thermal conductivity of the high-frequency thermal conductive adhesive sheet layer is 0.5-1.5W/mK, such as 0.5W/mK, 0.6W/mK, 0.7W/mK, 0.8W/mK, 0.9W/mK.
  • mK 1.0W/mK, 1.1W/mK, 1.2W/mK, 1.3W/mK, 1.4W/mK, 1.5W/mK, etc.
  • the high-frequency thermal conductive bonding sheet layer selected in the present invention is a high-frequency high thermal conductive bonding sheet, which has a relatively low dielectric constant and dielectric loss, so the thermal conductive substrate has a relatively low dielectric constant and dielectric loss.
  • the high-frequency thermally conductive adhesive sheet layer may be composed of at least one high-frequency thermally conductive adhesive sheet.
  • the low-profile copper foil layer, the high-frequency thermal conductive bonding sheet layer, the thin film resistance layer, and the resin layer can all be prepared from existing materials according to the existing preparation method; the thermal conductivity is 0.5-1.5W/
  • the mK thermally conductive adhesive sheet layer can also be obtained according to existing materials and existing preparation methods. Exemplary preparation methods are listed as follows:
  • the high-frequency thermal conductive bonding sheet in the present invention is to impregnate reinforcing materials (such as fiberglass cloth, fiberglass paper, etc.) with resin glue, and dry the solvent to obtain an uncured, semi-cured or fully cured bonding sheet;
  • the first or second resin layer in the present invention is obtained by coating resin glue on the thin film resistance layer or the low profile copper foil layer.
  • the resin glue used in the first resin layer, the high-frequency thermal conductive adhesive sheet layer and the second resin layer in the present invention can be selected from a known resin composition formula according to the required dielectric constant, dielectric loss, and thermal conductivity It is made by dissolving in an organic solvent.
  • the resin composition contains resin, initiator, filler, flame retardant, viscosity regulator, and other auxiliary agents.
  • the resin is selected from one or a mixture of at least two of polyphenylene ether resins with unsaturated double bonds, polybutadiene resins, polybutadiene copolymer resins, and elastomer block copolymers;
  • Polyphenylene ether resins with unsaturated double bonds are selected from polyphenylene ether resins with acryloyl groups at both ends, polyphenylene ether resins with styrene groups at both ends, and vinyl at both ends One of the polyphenylene ether resins or a mixture of at least two of them;
  • Polybutadiene resin is selected from 1,2-polybutadiene resin, maleic anhydride modified polybutadiene resin, acrylate modified polybutadiene resin, epoxy modified polybutadiene resin One or a mixture of at least two of the amine-modified polybutadiene resin, carboxy-terminated polybutadiene resin, and hydroxyl-terminated polybutadiene resin;
  • the polybutadiene copolymer resin is selected from polybutadiene-styrene copolymer resin, polybutadiene-styrene-divinylbenzene graft copolymer resin, maleic anhydride modified styrene-butadiene copolymer One or a mixture of at least two of the acrylate modified styrene-butadiene copolymer resin and the acrylate modified styrene-butadiene copolymer resin;
  • Elastomer block copolymer is selected from styrene-butadiene diblock copolymer, styrene-butadiene-styrene triblock copolymer, styrene-(ethylene-butene)-styrene triblock Copolymer, styrene-isoprene diblock copolymer, styrene-isoprene-styrene triblock copolymer, styrene-(ethylene-propylene)-styrene triblock copolymer and benzene One of the ethylene-(ethylene-butene) diblock copolymers or a mixture of at least two of them.
  • the filler is selected from boron nitride, aluminum nitride, silicon nitride, silicon carbide, silicon dioxide, titanium dioxide, aluminum oxide, magnesium oxide, zinc oxide, barium titanate, strontium titanate, magnesium titanate, calcium titanate, titanium Potassium acid, barium strontium titanate, lead titanate, glass powder, magnesium hydroxide, mica powder, talc, hydrotalcite, mullite, boehmite, kaolin, montmorillonite, calcium silicate or calcium carbonate One or a mixture of at least two of them;
  • the initiator is one of organic peroxide radical initiators and carbon-based radical initiators, or a mixture of at least two of them.
  • the organic solvent is selected from one or a mixture of at least two of aromatic hydrocarbon solvents such as toluene, xylene and mesitylene.
  • the preparation method of the low insertion loss high-frequency thermal conductive substrate is as follows:
  • the thin film resistance layer is deposited on the first low profile copper foil layer; the first resin layer is coated on the thin film resistance layer; the second resin layer is coated on the second low profile copper foil layer on.
  • Laminate the first low-profile copper foil layer, the thin-film resistance layer, the first resin layer, the thermally conductive adhesive sheet layer, the second resin layer and the second low-profile copper foil in sequence from top to bottom, and put them in The press is used for curing to make laminates, the curing temperature is 150-300°C (for example, 150°C, 180°C, 200°C, 250°C, 280°C or 300°C), and the curing pressure is 25-70kg/cm 2 (for example 25kg/cm 2 , 30kg/cm 2 , 35kg/cm 2 , 40kg/cm 2 , 50kg/cm 2 , 60kg/cm 2 or 70kg/cm 2 ).
  • the curing temperature is 150-300°C (for example, 150°C, 180°C, 200°C, 250°C, 280°C or 300°C)
  • the curing pressure is 25-70kg/cm 2 (for example 25kg/cm 2 , 30kg/cm 2 , 35
  • the second object of the present invention is to provide a printed circuit board, the printed circuit board comprising the low insertion loss high-frequency thermally conductive substrate as described in the first object.
  • the third object of the present invention is to provide the application of the low insertion loss high-frequency thermal conductive substrate as the circuit board in electronic products as described in the first object.
  • the low insertion loss high-frequency thermal conductive substrate of the present invention can meet the requirements of high-frequency high thermal conductivity electronic circuit substrates for low dielectric constant, low dielectric loss, low insertion loss, high thermal conductivity, high reliability and other comprehensive performance requirements.
  • the low insertion loss and high-frequency thermally conductive substrate can be used as a high-frequency thermally conductive power amplifier substrate.
  • the present invention has the following beneficial effects:
  • the low insertion loss high-frequency thermal conductive substrate of the present invention has high thermal conductivity (0.5W/mK ⁇ 1.5W/mK) and peel strength (greater than 0.7N/mm); it has a lower dielectric constant (less than 3.8 (10GHz, SPDR)) and dielectric loss (less than 0.0040 (10GHz, SPDR)) to meet the requirements of high-frequency substrates; low insertion loss (2GHz insertion loss is lower than -0.25dB/5inch, 5GHz insertion loss Less than -0.51dB/5inch), which can further reduce the heat generated by the substrate; it has a higher integration level, which can further improve the reliability of the substrate; meets the low dielectric constant and low dielectric loss of the high-frequency and high thermal conductivity electronic circuit substrate , Low insertion loss, high thermal conductivity, high reliability and other comprehensive performance requirements, can be used as circuit boards in electronic products.
  • Figure 1 is a structural diagram of a low insertion loss high-frequency thermal conductive substrate in an embodiment of the present invention, in which: 1 is the first low-profile copper foil layer; 2 is the thin film resistance layer; 3 is the first resin layer; 4 is the high-frequency thermal conductive adhesive Bonding layer; 5 is the second resin layer; 6 is the second low profile copper foil layer.
  • Examples 1-5 respectively provide a low-insertion loss high-frequency thermally conductive substrate.
  • the schematic structural diagram is shown in FIG. 1.
  • the low-insertion loss high-frequency thermally conductive substrate includes first low-profile copper bonded together from top to bottom.
  • the preparation method of the low insertion loss high-frequency thermal conductive substrate is as follows:
  • the thin film resistance layer 2 is deposited on the first low profile copper foil layer 1; the first resin layer 3 is coated on the thin film resistance layer 2; the second resin layer 5 is coated on the second On the low-profile copper foil layer 6.
  • Table 1 shows the structure settings and test results of the low-insertion loss high-frequency heat-conducting substrates according to Examples 1-5 of the present invention:
  • the low insertion loss high-frequency thermal conductive substrate of the present invention has higher thermal conductivity, peel strength and integration, and has a lower dielectric constant, dielectric loss and insertion loss.
  • Dielectric constant (Dk) and dielectric loss (Df) The SPDR method is used to test the dielectric constant Dk and dielectric loss Df of the board at a frequency of 10 GHz.
  • Comparative Example 1 Compared with Example 1, the thickness of the first resin layer 3 and the second resin layer 5 coated on the low-profile copper foil is thicker, the dielectric constant of the thermally conductive substrate will decrease, and the thermal conductivity of the thermally conductive substrate The rate will be low.
  • Example 2 compared with Example 2, the roughness of the first low-profile copper foil layer 1 and the second copper foil layer 6 is higher, and the 2GHz insertion loss and the 5GHz insertion loss of the thermally conductive substrate are both higher.
  • Example 3 Compared with Example 3, in Comparative Example 3, the thermal conductivity of the thermally conductive adhesive sheet 4 is lower, and the thermal conductivity of the thermally conductive substrate is lower.
  • Comparative Example 4 compared with Example 4, the thickness of the first resin layer 3 and the second resin layer 5 coated on the low-profile copper foil layer is lower, and the peel strength of the thermally conductive substrate is lower.
  • Example 3 in Comparative Example 6 the dielectric loss of the thermally conductive adhesive sheet 4 is higher, and the dielectric loss of the thermally conductive substrate is higher.
  • Comparative Example 7 does not contain the first resin layer 3 and the second resin layer 5, and therefore the peel strength of the thermally conductive substrate is lower.
  • Example 5 Compared with Example 5, in Comparative Example 8, the thermal conductivity of the thermally conductive adhesive sheet 4 is higher, and the thermal conductivity of the thermally conductive substrate is also higher. However, because of the use of special high thermal conductivity fillers, the peel strength of the thermal conductive substrate is low.
  • the thermally conductive substrate of the present invention has higher thermal conductivity and peel strength, and has lower dielectric constant, dielectric loss and insertion loss (including 2GHz insertion loss and 5GHz insertion loss); when the setting parameters of the thermally conductive substrate If it is not within the scope of the present invention, it will affect the thermal conductivity, peel strength, dielectric constant, dielectric loss and insertion loss of the substrate, thereby affecting the use of the thermally conductive substrate.

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Abstract

本发明提供了一种低插损高频导热基板及其应用，所述低插损高频导热基板自上而下依次包括结合在一起的以下各层：粗糙度Rz≤5μm的第一低轮廓铜箔层；薄膜电阻层；厚度为2-20μm的第一树脂层；介电常数低于3.8、介电损耗小于0.0040、热导率为0.5-1.5W/mK的高频导热粘结片层；厚度为2-20μm的第二树脂层和粗糙度Rz≤5μm的第二低轮廓铜箔层；所述基板具有较高的热导率和剥离强度以及较低的介电常数和介电损耗和较低的插损，具有较高的集成度，提高了基板的可靠性；可作为线路板应用于电子产品中。

Description

一种低插损高频导热基板及其应用 技术领域
本发明属于电子材料技术领域，涉及一种低插损高频导热基板及其应用。
背景技术
随着印刷线路板(PCB)向着高密度、多层化方向的不断发展，元器件在PCB上搭载、安装的空间大幅减少，整机电子产品对功率元器件的功率要求越来越高，小空间、大功率不可避免地产生更多的热量聚集。另一方面，随着现代通讯技术的快速发展，电子设备的工作频率越来越高，发热量越来越大。总之，把大量强大功能集成到更小的组件中，驱使印制板走向高密度化，同时信号传输高频化或高速数字化的发展，这两大因素驱使着印制板的工作温度急剧地上升。如果积聚的热量不能及时排出，将使设备的工作温度升高，长此以往，将造成元器件电气性能下降甚至毁损，严重损害设备的寿命和可靠性。大量试验和统计数据表明，电子元器件(最佳工作温度后)的温升2℃其可靠性便下降10％，温升50℃的使用寿命只有温升25℃的1/6，因此，印制板工作温度已成为影响可靠性和使用寿命的最重要的因素。
提高线路集成度及PCB功率密度的需求与日俱增，高频印刷线路板热管理的重要性更加突出。众所周知，材料的导热系数对于减小温升至关重要。高频线路板的热量本质上与线路板上的损耗密切相关。例如，表面粗糙的铜箔比表面光滑的铜箔损耗大。另一种影响损耗的材料参数是印刷线路板介质层材料的损耗因子，损耗因子越低，介电损耗越小，印刷线路板产生的热量也会越少。此外，介电常数较低的印刷线路板材料也会比介电常数较高的材料产生的损耗小，产生的热量少。一般而言，选择具有良好性能的线路板材料，如高导热系 数，较低的损耗因子，光滑的铜箔表面以及低介电常数，不仅有助于设计高性能的印刷线路板，还能够改善热管理。
无源元件(线状和非线状电阻，电容，线圈，保险丝)是每个电子设备的基本组成部分，并占用印制板大量表面积。然而同时，小尺寸规格无源元件(如0402和0201)自动电装难度大，且焊点质量难以保证。多层板内埋无源元件技术可以克服这些问题，在高端产品(比如手机)制造中可有广阔应用。随着元件越变越小，制造商和组装者在这类印制板的制造、组装、检验、操作和费用控制等方面面临着许多挑战。由于减少了焊点数量，内埋无源元件更加可靠。同时，内埋式元件增加了线路密度，提升了电子设备的电气性能和功能。虽然内埋无源元件有很多优势，但是依旧有一些问题，包括断裂分层及各种埋置元件的稳定性问题。因为内埋元件通常需要多层叠构设计，而不同材料的CTE不匹配将会产生较大的热应力。与分立式元件不同，有缺陷的内埋式元件无法替换，这意味着即使一个小元件出现问题也会造成整个线路板报废。所以，保持元件长期稳定和可靠，是制造商运用这一技术的关注点。
内埋无源元件的概念在很多年前就已出现在线路板行业内。上世纪60年代末，第一次试验制作内埋电容；上世纪70年代初，开始应用NiP和NiCr层制作内埋薄层电阻；到目前为止，已开发了许多其他用于制作内埋式无源元件的材料。另外，上世纪90年代后期，CTS、3M、Oak Mitsui、Sanmina-SCI和其他公司也开始研发内埋无源元件和材料。目前，内埋薄膜电阻和材料已发展得较为成熟，代表公司有DuPont电子技术、Ohmega、Ticer、Sheldahl、W.L.CORE&ASSOCIATE和Georgia技术研究所。到本世纪，亚洲地区也开始了此项技术的研究。目前，内埋技术应用范围依旧很小，大多用于军事、航空、航天等电子产品领域。尽管如此，高度发达却不昂贵的民用电子产品对该技术 的需求在不断增长，如手机、笔记本电脑和网络设备等，内埋无源元件技术由此受到广泛关注，并再一次成为焦点，被认为将是印制板发展的下一个关键技术。
之前的研究都集中于单一材料，只是单独地研究薄膜电阻或是聚合厚膜电阻。结合薄膜和厚膜电阻技术，可以制造所有可用范围内的电阻值。电阻值范围小时使用薄膜电阻可大量减小面积，同时获得精确的阻值；使用厚膜电阻可获得较大阻值，公差相对较大。聚合厚膜(PTF)电阻通常是用聚合物电阻浆制作，适用于不同印制板基材。一般，电阻浆组成是碳(炭黑和石墨)和/或混合聚合树脂的银填料(含溶剂和稀释剂，有时加入绝缘粉末填料使之具有适当的流变性能)。印制板上PTF电阻浆固化温度不应超过180℃，但一些制造商可提供固化温度达到220℃的电阻膏。电阻浆和电阻膏的方阻范围远大于薄膜电阻材料，但阻值公差较大，稳定性有限。聚合物和铜层接触面间氧化层会引起阻值偏差，且更易发生CTE不匹配造成的分层和断裂。
在厚、薄膜混合电路中，将无源分离元件做在基板上，是提高集成度的方法，这一方法也同样适用于印制板。用埋入式电阻或电容代替分离的电阻、电容元件，这样不仅可以提高密度，与一般表面封装元件相比，在高速、高性能传输印制板中，其电性能也大大提高，其优越性表现在以下几个方面：(1)有效提高线路密度。可以代替分离元件，节省板面空间，与印制板合为一体，其位置也不受其他元件限制，结果是印制板重量减轻，尺寸缩小。在有些应用中，还可以从双表面封装转为单表面封装，减轻封装负担。(2)提高电气性能。薄膜电阻的采用，大大减少了电阻元件相关的引人、引出线路，有望对所有的信号线进行匹配，在高频传输中极为关键，电感系数极低(小于纳亨)，还大大降低表面电磁干扰(EMI)。(3)改善机械性能。薄膜电阻不会象有引线或表面封 装电阻元件一样，受冲击振动影响；也避免了由潮湿、灰尘引起的表面封装电阻的组装问题。(4)提高可靠性。焊点数大幅度减少，经诸多的应用实践表明，其长期可靠性极佳。(5)降低成本。薄膜电阻的应用，减少了分离电阻的用量，由于尺寸缩小，基材用量也下降，且返工工作量减少，这些都有利于降低成本。近年来高速、高性能电子产品骤增，对应高密度的同时，还要对应高频、高速传输，因此，电路板的表面封装需要转换到埋置元件PCB上来。不受寄生元件或者噪音影响，而又能高速地传输大容量的信号的关键影响因素在于电阻。内埋式电阻作业时的热稳定性是埋电阻技术是否成功的关键因素。电流通过电阻时产生热量，并且会迅速从印制板扩散至周边环境。因此需要迅速将产生的热量扩散出去，这就要求基板具有导热功能，同时要求基板具有较低的插损，也可以产生更少的热量。
因此，开发一种低插损高频导热基板非常有必要。
发明内容
针对现有技术的不足，本发明的目的在于提供一种导热基板及其应用，特别是提供一种低插损高频导热基板及其应用，所述导热基板具有较高的热导率、剥离强度和集成度，且具备较低的介电常数、介电损耗和插损，可满足高频高导热电子电路基板对低介电常数、低介电损耗、低插损、高热导率、高可靠性等综合性能的要求，因此可作为线路板在电子产品中应用。
为达到此发明目的，本发明采用以下技术方案：
本发明的目的之一在于提供一种低插损高频导热基板，自上而下依次包括结合在一起的如下各层：
粗糙度Rz≤5μm的第一低轮廓铜箔层；
薄膜电阻层；
厚度为2-20μm的第一树脂层；
介电常数低于3.8、介电损耗小于0.0040、热导率为0.5-1.5W/mK的高频导热粘结片层；
厚度为2-20μm的第二树脂层；
和，粗糙度Rz≤5μm的第二低轮廓铜箔层。
本发明所述的低插损高导热基板具有0.5W/mK～1.5W/mK热导率、具有低于-0.25dB/5inch(2GHz)以及低于-0.51dB/5inch(5GHz)的插损，可以满足高频基板的使用要求；具有较低的插损，可进一步降低高频基板产生的热量；基板中加入薄膜电阻层，使制备的基板具有较高的集成度，可进一步提高基板的可靠性。
在本发明中，所述第一低轮廓铜箔层的粗糙度Rz≤5μm，例如0.1μm、0.5μm、1μm、1.5μm、2μm、2.5μm、3μm、3.5μm、4μm、4.5μm、5μm等。
在本发明中，所述第二低轮廓铜箔层的粗糙度Rz≤5μm，例如0.1μm、0.5μm、1μm、1.5μm、2μm、2.5μm、3μm、3.5μm、4μm、4.5μm、5μm等。
优选地，所述第一低轮廓铜箔层的粗糙度和第二铜箔层的粗糙度相同。
本发明中，采用第一低轮廓铜箔层和第二低轮廓铜箔层的目的在于降低基板的插损，铜箔的粗糙度越低，基板的插损就越低；当第一低轮廓铜箔层和第二铜箔层的粗糙度偏高，则基板的插损偏高，影响基板的使用寿命。
在本发明中，所述薄膜电阻层的厚度为0.1-1.0μm，例如0.1μm、0.2μm、0.3μm、0.4μm、0.5μm、0.6μm、0.7μm、0.8μm、0.9μm、1.0μm等。
在本发明中，薄膜电阻层是为了提高基板的集成度，将电阻内埋到基板中，最终提高基板的可靠性。
在本发明中，所述第一树脂层的厚度为2-20μm，例如2μm、3μm、4μm、 5μm、6μm、7μm、8μm、9μm、10μm、11μm、12μm、13μm、14μm、15μm、16μm、17μm、18μm、19μm、20μm等。
在本发明中，所述第二树脂层的厚度为2-20μm，例如2μm、3μm、4μm、5μm、6μm、7μm、8μm、9μm、10μm、11μm、12μm、13μm、14μm、15μm、16μm、17μm、18μm、19μm、20μm等。
优选地，所述第一树脂层和第二树脂层的厚度相同。
在本发明中，第一树脂层和第二树脂层是为了提高基板介质层与铜箔的剥离强度，因为铜箔的粗糙度比较低，与介质层的结合力比较低，需要在铜箔上涂覆一层树脂层来提高剥离强度。
本发明选用的树脂层的厚度为2-20μm，制备的基板具有较好的剥离强度、介电性能和热导率；当树脂层的厚度小于2μm，则制备的基板达不到提高剥离强度的目的；当树脂层的厚度大于20μm，则会影响基板的介电性能，因为树脂层的介电常数比较低，如果树脂层比较厚，则基板的介电常数会明显降低；另外，树脂层的热导率也比较低，如果树脂层比较厚，则基板的热导率也会有所下降。
本发明所述高频导热粘结片层的介电常数低于3.8(10GHz，SPDR)，例如其介电常数可以为3.0、3.2、3.5、3.8等；介电损耗小于0.0040(10GHz，SPDR)，例如0.0012、0.0015、0.0018、0.0020、0.0022、0.0025、0.0028、0.0030、0.0032、0.0035、0.0038、0.0039等。
在本发明中，所述高频导热粘结片层的热导率为0.5-1.5W/mK，例如0.5W/mK、0.6W/mK、0.7W/mK、0.8W/mK、0.9W/mK、1.0W/mK、1.1W/mK、1.2W/mK、1.3W/mK、1.4W/mK、1.5W/mK等。
本发明选用的高频导热粘结片层为高频高导热粘结片，具有较低的介电常 数和介电损耗，因此所述的导热基板具有比较低的介电常数和介电损耗。
在本发明中，所述高频导热粘结片层可以由至少一张高频导热粘结片构成。
在本发明中，所述低轮廓铜箔层、高频导热粘结片层、薄膜电阻层、树脂层均可以由现有材料，根据现有制备方法制备得到；热导率0.5-1.5W/mK的导热粘结片层亦可以根据现有材料和现有制备方法得到。示例性的制备方法列举如下：
本发明中的高频导热粘结片层为将增强材料(例如玻纤布、玻纤纸等)浸渍树脂胶液，烘干溶剂，获得未固化、半固化或完全固化的粘结片层；本发明中的第一或第二树脂层为将树脂胶液涂覆在薄膜电阻层上或低轮廓铜箔层上获得。
本发明中的第一树脂层、高频导热粘结片层以及第二树脂层中使用的树脂胶液，均可以根据需要的介电常数、介质损耗、导热系数选取已知的树脂组合物配方溶于有机溶剂制得，例如树脂组合物包含树脂、引发剂、填料、阻燃剂、粘度调节剂、其它助剂等。
树脂选自带有不饱和双键的聚苯醚树脂、聚丁二烯树脂、聚丁二烯共聚物树脂、弹性体嵌段共聚物中的一种或为其中至少两种的混合物；
带有不饱和双键的聚苯醚树脂选自两末端改性基为丙烯酰基的聚苯醚树脂、两末端改性基为苯乙烯基的聚苯醚树脂、两末端改性基为乙烯基的聚苯醚树脂中的一种或为其中至少两种的混合物；
聚丁二烯树脂选自1，2-聚丁二烯树脂、马来酸酐改性的聚丁二烯树脂、丙烯酸酯改性的聚丁二烯树脂、环氧改性的聚丁二烯树脂、胺基改性的聚丁二烯树脂、端羧基改性的聚丁二烯树脂、端羟基改性的聚丁二烯树脂中的一种或为其中至少两种的混合物；
聚丁二烯共聚物树脂选自聚丁二烯-苯乙烯共聚物树脂、聚丁二烯-苯乙烯-二乙烯基苯接枝共聚物树脂、马来酸酐改性苯乙烯-丁二烯共聚物树脂和丙烯酸酯改性苯乙烯-丁二烯共聚物树脂中的一种或为其中至少两种的混合物；
弹性体嵌段共聚物选自苯乙烯-丁二烯二嵌段共聚物、苯乙烯-丁二烯-苯乙烯三嵌段共聚物、苯乙烯-(乙烯-丁烯)-苯乙烯三嵌段共聚物、苯乙烯-异戊二烯二嵌段共聚物、苯乙烯-异戊二烯-苯乙烯三嵌段共聚物、苯乙烯-(乙烯-丙烯)-苯乙烯三嵌段共聚物和苯乙烯-(乙烯-丁烯)二嵌段共聚物中的一种或为其中至少两种的混合物。
填料选自氮化硼、氮化铝、氮化硅、碳化硅、二氧化硅、二氧化钛、氧化铝、氧化镁、氧化锌、钛酸钡、钛酸锶、钛酸镁、钛酸钙、钛酸钾、钛酸锶钡、钛酸铅、玻璃粉、氢氧化镁、云母粉、滑石粉、水滑石、莫来石、勃姆石、高岭土、蒙脱土、硅酸钙或碳酸钙中的一种或为其中至少两种的混合物；
引发剂为有机过氧化物自由基引发剂、碳系自由基引发剂中的一种或为其中至少两种的混合物。
有机溶剂选自甲苯、二甲苯、均三甲苯等芳香族烃类溶剂中的一种或为其中至少两种的混合物。
在本发明中，所述低插损高频导热基板的制备方法如下：
(1)将所述薄膜电阻层沉积在第一低轮廓铜箔层上；所述第一树脂层涂覆在薄膜电阻层上；所述第二树脂层涂覆在第二低轮廓铜箔层上。
(2)自上而下依次将第一低轮廓铜箔层、薄膜电阻层、第一树脂层、导热粘结片层、第二树脂层和第二低轮廓铜箔层叠合在一起，放进压机进行固化制得层压板，固化的温度为150-300℃(例如150℃、180℃、200℃、250℃、280℃ 或300℃)，固化的压力为25-70kg/cm 2(例如25kg/cm 2、30kg/cm 2、35kg/cm 2、40kg/cm 2、50kg/cm 2、60kg/cm 2或70kg/cm 2)。
本发明的目的之二在于提供一种印制电路板，所述印制电路板包括如目的之一所述的低插损高频导热基板。
本发明的目的之三在于提供如目的之一所述的低插损高频导热基板作为线路板在电子产品中的应用。
本发明所述的低插损高频导热基板可以满足高频高导热电子电路基板对低介电常数、低介电损耗、低插损、高热导率、高可靠性等综合性能的要求，可以作为线路板在电子用品中应用，例如所述低插损高频导热基板可用作高频导热功放基板。
相对于现有技术，本发明具有以下有益效果：
本发明所述的低插损高频导热基板具有较高的热导率(0.5W/mK～1.5W/mK)和剥离强度(大于0.7N/mm)；具有较低的介电常数(小于3.8(10GHz，SPDR))和介电损耗(小于0.0040(10GHz，SPDR))，满足高频基板的使用要求；具有较低的插损(2GHz插损低于-0.25dB/5inch，5GHz插损低于-0.51dB/5inch)，可进一步降低基板产生的热量；具有较高的集成度，可以进一步提高基板的可靠性；满足高频高导热电子电路基板对低介电常数、低介电损耗、低插损、高热导率、高可靠性等综合性能的要求，可作为线路板在电子产品中应用。
附图说明
图1是本发明实施例中低插损高频导热基板的结构示意图，其中：1为第一低轮廓铜箔层；2为薄膜电阻层；3为第一树脂层；4为高频导热粘结片层；5为第二树脂层；6为第二低轮廓铜箔层。
具体实施方式
下面通过具体实施方式来进一步说明本发明的技术方案。本领域技术人员应该明了，所述实施例仅仅是帮助理解本发明，不应视为对本发明的具体限制。
实施例1-5
实施例1-5中分别提供一种低插损高频导热基板，结构示意图如图1所示，所述低插损高频导热基板自上而下依次包括结合在一起的第一低轮廓铜箔层1、薄膜电阻层2、第一树脂层3、高频导热粘结片层4、第二树脂层5和第二低轮廓铜箔层6。
该低插损高频导热基板的制备方法如下：
(1)将所述薄膜电阻层2沉积在第一低轮廓铜箔层1上；所述第一树脂层3涂覆在薄膜电阻层2上；所述第二树脂层5涂覆在第二低轮廓铜箔层6上。
(2)自上而下依次将第一低轮廓铜箔层、薄膜电阻层、第一树脂层、导热粘结片层、第二树脂层和第二低轮廓铜箔层叠合在一起，放进压机进行固化制得层压板，固化的温度为150-300℃，固化的压力为25-70kg/cm 2。
表1为本发明实施例1-5所述低插损高频导热基板的结构设置和测试结果：
表1
Figure PCTCN2019077164-appb-000001
Figure PCTCN2019077164-appb-000002
从表1可知，本发明所述的低插损高频导热基板具有较高的热导率、剥离强度和集成度，且具备较低的介电常数、介电损耗和插损。
比较例1-8
比较例1-8的的导热基板与实施例1-5的导热基板相比不同之处在于各层的结构设置以及性能测定结果如表2和表3所示。
表2
Figure PCTCN2019077164-appb-000003
表3
Figure PCTCN2019077164-appb-000004
Figure PCTCN2019077164-appb-000005
以上实施例和比较例中对基板的性能测试方法如下：
(a)剥离强度(PS)：按照IPC-TM-650 2.4.8方法中“热应力后”实验条件，测试板材的剥离强度。
(b)介电常数(Dk)和介电损耗(Df)：采用SPDR法，在10GHz频率下，测试板材的介电常数Dk和介电损耗Df。
(c)2GHz插损和5GHz插损：按照IPCTM-650中2.5.5.12A所规定的方法进行测定。
(d)热导率：采用导热系数测试仪，按照ASTMD5470方法进行测试。
由表1、表2和表3的数据对比，可以看出：
比较例1相比于实施例1，涂覆在低轮廓铜箔上的第一树脂层3和第二树脂层5的厚度偏厚，导热基板的介电常数会降低，同时导热基板的热导率均会偏低。
比较例2相比于实施例2，第一低轮廓铜箔层1和第二铜箔层6的粗糙度偏高，则导热基板的2GHz插损和5GHz插损均偏高。
比较例3相比于实施例3，导热粘结片4的热导率偏低，则导热基板的热导率偏低。
比较例4相比于实施例4，涂覆在低轮廓铜箔层上的第一树脂层3和第二树脂层5的厚度偏低，则导热基板的剥离强度偏低。
比较例5相比于实施例3，导热粘结片4的介电常数偏高，则导热基板的 介电常数偏高。
比较例6相比于实施例3，导热粘结片4的介电损耗偏高，则导热基板的介电损耗偏高。
比较例7相比于实施例3，不含第一树脂层3和第二树脂层5，则导热基板的剥离强度偏低。
比较例8相比于实施例5，导热粘结片4的热导率较高，则导热基板的热导率也较高。但是因为采用了特殊的高导热填料，导热基板的剥离强度偏低。
本发明所述的导热基板具有较高的热导率和剥离强度，且具有较低的介电常数、介电损耗和插损(包括2GHz插损和5GHz插损)；当导热基板的设置参数不在本发明限定的范围之内，则会影响基板的热导率、剥离强度、介电常数、介电损耗以及插损，从而影响导热基板的使用。
申请人声明，以上所述仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，所属技术领域的技术人员应该明了，任何属于本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到的变化或替换，均落在本发明的保护范围和公开范围之内。

Claims (7)

  1. 一种低插损高频导热基板，其特征在于，所述导热基板自上而下依次包括结合在一起的如下各层：
    粗糙度Rz≤5μm的第一低轮廓铜箔层；
    薄膜电阻层；
    厚度为2-20μm的第一树脂层；
    介电常数低于3.8、介电损耗小于0.0040、热导率为0.5-1.5W/mK的高频导热粘结片层；
    厚度为2-20μm的第二树脂层；
    和，粗糙度Rz≤5μm的第二低轮廓铜箔层。
  2. 根据权利要求1所述的低插损高频导热基板，其特征在于，所述第一低轮廓铜箔层的粗糙度和第二低轮廓铜箔层的粗糙度相同。
  3. 根据权利要求1所述的低插损高频导热基板，其特征在于，所述薄膜电阻层的厚度为0.1-1.0μm。
  4. 根据权利要求1-3任一项所述的低插损高频导热基板，其特征在于，所述第一树脂层和第二树脂层的厚度相同。
  5. 根据权利要求1-4任一项所述的低插损高频导热基板，其特征在于，所述高频导热粘结片层由至少一张导热粘结片构成。
  6. 一种印制电路板，其特征在于，所述印制电路板包括如权利要求1-6任一项所述的低插损高频导热基板。
  7. 根据权利要求1-6中任一项所述的低插损高频导热基板作为线路板在电子产品中的应用。
PCT/CN2019/077164 2019-01-21 2019-03-06 一种低插损高频导热基板及其应用 WO2020151052A1 (zh)

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Citations (4)

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Publication number Priority date Publication date Assignee Title
JPS5524499A (en) * 1978-08-09 1980-02-21 Siemens Ag Electric film circuit and method of manufacturing same
CN101194326A (zh) * 2005-02-22 2008-06-04 奥克-三井有限公司 用于形成电阻器和电容器的多层构造
CN202285457U (zh) * 2011-10-21 2012-06-27 松扬电子材料(昆山)有限公司 散热基材
CN205510525U (zh) * 2016-03-25 2016-08-24 金安国纪科技（杭州）有限公司 一种有机树脂导热覆铜板

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5524499A (en) * 1978-08-09 1980-02-21 Siemens Ag Electric film circuit and method of manufacturing same
CN101194326A (zh) * 2005-02-22 2008-06-04 奥克-三井有限公司 用于形成电阻器和电容器的多层构造
CN202285457U (zh) * 2011-10-21 2012-06-27 松扬电子材料(昆山)有限公司 散热基材
CN205510525U (zh) * 2016-03-25 2016-08-24 金安国纪科技（杭州）有限公司 一种有机树脂导热覆铜板

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