Composition for inkjet printing and method of manufacturing dielectric substrate with high thermal conductivity using same

Abstract

The present invention relates to a method for manufacturing a heat sink and a substrate, in particular, a printed circuit board (PCB), having excellent thermal conductivity by inkjet printing an inkjet composition (ink) made of a resin and a ceramic such as alumina (Al2O3), silicon nitride (Si3N4), boron nitride (BN), or aluminum nitride (AlN). More specifically, the present invention relates to: a composition in which the contents of alumina, silicon nitride, boron nitride, aluminum nitride, and / or a resin are controlled; and a method for creating an insulating layer, a heat sink, etc., having excellent thermal conductivity and electrically insulating properties, in a PCB by inkjet printing using the composition.

Description

Inkjet printing composition and method for manufacturing a dielectric substrate having high thermal conductivity using the same

[0001] The present invention relates to a method for manufacturing a ceramic-resin composite substrate with excellent thermal conductivity, particularly a printed circuit board (PCB), by inkjet printing using a ceramic ink containing a ceramic such as alumina (Al2O3), silicon nitride (Si3N4), boron nitride (BN), aluminum nitride (AlN), etc., and a resin ink containing a resin such as epoxy resin. More specifically, the invention relates to a composition in which the ceramic and / or resin content is controlled, and a method for implementing a PCB dielectric substrate (insulating layer) and a thermal dissipation substrate, etc., with excellent thermal conductivity and insulation properties using the same by an inkjet printing method.

[0002] A printed circuit board includes a circuit pattern formed on an insulating layer, and various electronic components can be mounted on the printed circuit board. The electronic components mounted on the printed circuit board may be heat-generating elements. The heat emitted by these heat-generating elements can degrade the performance of the printed circuit board. To absorb the heat emitted by these heat-generating elements and dissipate it outside the board, a thermally conductive insulating layer, a heat dissipation substrate, etc., may be utilized.

[0003] There is a conventional method for forming an insulating layer of a printed circuit board, etc., by applying a high-viscosity liquid composition mixed with resin and filler through S-knife, gravure, flexo, screen, rotary screen, slot die, micro-gravure coating method, etc.

[0004] However, insulating layers produced by conventional methods have insufficient thermal conductivity, making it difficult to effectively handle the large amount of heat emitted by the device. Furthermore, conventional substrates made of materials such as aluminum nitride are sintered substrates; since sintered substrates must be baked at significantly high temperatures, they are extremely expensive. Moreover, these substrates are brittle, and commercialization is difficult because they are not easy to use in the lamination process. Consequently, the only fields where materials such as aluminum nitride are currently used as substrates are those that emit large amounts of heat, such as automobile engines, and even then, they are used in extremely small quantities. Even when applied to automobiles, the sintered substrates break due to the vehicle's jolting movements. Therefore, there is a need for research on substrates produced by methods other than sintering.

[0005] The first objective of the present invention is to provide an inkjet printing composition comprising a low-viscosity ink made of high thermal conductivity ceramics such as alumina (Al2O3), silicon nitride (Si3N4), boron nitride (BN), and aluminum nitride (AlN), which can form a substrate with excellent thermal conductivity and insulation properties.

[0006] The second objective of the present invention is to provide a method for manufacturing a printed circuit board and a heat dissipation substrate having excellent thermal conductivity and insulation properties by an inkjet printing method using the above-mentioned inkjet printing composition.

[0007] The objectives of the present invention are not limited to those mentioned above, and other objectives and advantages of the present invention not mentioned may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objectives and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0008] To achieve the above objective, according to one embodiment of the present invention, a composition for inkjet printing may be provided comprising: a ceramic ink made of a ceramic with high thermal conductivity such as alumina (Al2O3), silicon nitride (Si3N4), boron nitride (BN), aluminum nitride (AlN), etc.; and a resin ink made of a resin such as epoxy resin.

[0009] According to one embodiment of the present invention, by using the inkjet printing composition according to one embodiment of the present invention, an inkjet printed composition in the form of a composite that can be used in a printed circuit board and / or a heat dissipation substrate having high thermal conductivity and excellent insulation, composed of ceramic-resin (resin)-pores, can be provided.

[0010] According to one embodiment of the present invention, an inkjet printed composition can be provided in which the ratio of resin is 5% to 50% when the total volume of the ceramic, resin, and pores is 100 volume%.

[0011] According to one embodiment of the present invention, an inkjet printed composition comprising 50 to 85 volume% of the alumina can be provided.

[0012] According to one embodiment of the present invention, an inkjet-printed composition comprising 50 to 85 volume% of the silicon nitride can be provided.

[0013] According to one embodiment of the present invention, an inkjet-printed composition comprising 50 to 85 volume% of the boron nitride can be provided.

[0014] According to one embodiment of the present invention, an inkjet-printed composition comprising 50 to 85 volume% of the aluminum nitride can be provided.

[0015] According to one aspect of the present invention, the resin is made of a thermosetting resin, and an inkjet printing composition comprising one of polyacrylates resin, epoxy resin, phenolic resin, polyamides resin, polyimide resin, unsaturated polyesters resin, polyphenylene ether resin (PPE), polyphenylenesulfides resin, cyanate ester resin, and benzocyclobutene (BCB) may be provided.

[0016] According to one embodiment of the present invention, the inkjet printing composition may provide an inkjet printing composition having a viscosity of 1 to 25 cP.

[0017] According to one embodiment of the present invention, the inkjet printing composition can provide an inkjet printing composition with different viscosities depending on the amount of solvent.

[0018] According to another aspect of the present invention, a method for manufacturing a substrate by printing an inkjet printing composition according to one aspect of the present invention using inkjet printing can be provided.

[0019] According to another aspect of the present invention, a method for manufacturing a heat sink can be provided by printing an inkjet printing composition according to one aspect of the present invention using inkjet printing.

[0020] According to another aspect of the present invention, a printed circuit board manufactured according to one aspect of the present invention can be provided.

[0021] By using an inkjet printing composition comprising ceramics and resins according to the present invention, it is possible to manufacture a heat sink and a substrate, particularly an insulating layer of a PCB, with high thermal conductivity and / or insulation properties through inkjet printing. The thermal conductivity value of the insulating layer manufactured by an inkjet printing method comprising the components of the above composition generally has a much higher value than the thermal conductivity value of a substrate formed by applying a high-viscosity liquid composition mixed with a resin and a filler, which is widely known in the past.

[0022] In addition to the effects described above, the effects of the present invention are described together with the details for implementing the invention below.

[0023] FIG. 1 illustrates the structure and heat transfer path of a substrate inkjet printed using a low-viscosity ceramic-resin composition comprising one of alumina (Al2O3), silicon nitride (Si3N4), boron nitride (BN), and aluminum nitride (AlN) according to one embodiment of the present invention, and the structure and heat transfer path of a substrate formed by applying a high-viscosity liquid composition made by mixing a conventional ceramic material with a resin using a filler. In this case, the vol% of the ceramic and the vol% of the resin have nearly the same value, and the vol% of the pores is 0.

[0024] FIG. 2 schematically illustrates the structure and heat transfer path of a substrate inkjet printed using a low-viscosity ceramic-resin composition (ink) comprising one of alumina (Al2O3), silicon nitride (Si3N4), boron nitride (BN), and aluminum nitride (AlN) according to one embodiment of the present invention. In this case, the vol% of the ceramic has a value greater than the vol% of the resin. The vol% of the pores is 0.

[0025] Figure 3 is a graph showing the theoretical calculation results of the thermal conductivity of a substrate composed according to Experimental Example 1 of the present invention.

[0026] Figure 4 illustrates the configuration of the printed circuit board and the specifications of each component used in the simulation analysis of heat dissipation according to Experimental Example 2 of the present invention.

[0027] Figure 5 is the result of a simulation analysis of heat dissipation according to Experimental Example 2 of the present invention.

[0028] Figure 6 is a graph showing the theoretical calculated value of the thermal conductivity of a ceramic-resin-pore composite prepared using alumina ink according to Experimental Example 1 of the present invention (red dots) and the experimental value of the thermal conductivity of a substrate formed by inkjet printing a composition containing alumina according to Experimental Example 3 (black dots).

[0029] The aforementioned objectives, features, and advantages are described in detail below with reference to the description of the invention, and accordingly, a person skilled in the art to which the invention pertains will be able to easily implement the technical concept of the invention. In describing the invention, detailed descriptions of known technologies related to the invention are omitted if it is determined that such descriptions may unnecessarily obscure the essence of the invention. The terms described below are terms used in consideration of their functions and operations in the invention, and the meaning of each term should be interpreted based on the content throughout this specification.

[0030] As used in this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0031] Where terms such as "comprising," "having," "consisting of," "containing," or "having" are used for a component in this specification, other parts may be added unless "only" is used. Where a component is expressed in the singular, it includes cases where it is included in the plural unless specifically stated otherwise.

[0032] In interpreting the components in this specification, they are interpreted to include an error range even if there is no separate explicit description.

[0033] In this specification, the standard for units is based on volume unless otherwise specifically stated. For example, "%" is interpreted as volume % (vol%).

[0034] The present invention will be described in more detail below.

[0035] Inkjet printing composition

[0036] The inkjet printing composition of the present invention may include a ceramic ink comprising one of a ceramic of alumina (Al2O3), silicon nitride (Si3N4), boron nitride (BN), and aluminum nitride (AlN); and a resin ink comprising a resin.

[0037] According to one embodiment of the present invention, the composition printed with the inkjet printing composition (ink) may consist of the ceramic, the resin, and the pores. When the total volume of the printed composition is 100 volume%, the resin may be included in an amount of 5 to 50 volume%, for example, 7 to 42 volume%. If the resin content is below the lower limit, the mechanical properties of the composition may be reduced, making it susceptible to damage from physical impact. If the resin content exceeds the upper limit, the thermal properties may be degraded as a film consisting solely of resin is formed in the composition.

[0038] According to one embodiment of the present invention, the resin may be a thermosetting resin and may include one of polyacrylates resin, epoxy resin, phenolic resin, polyamides resin, polyimides resin, unsaturated polyesters resin, polyphenylene ether resin (PPE), polyphenylenesulfides resin, cyanate ester resin, and benzocyclobutene (BCB).

[0039] According to one embodiment of the present invention, the resin may be an epoxy resin. The epoxy resin may be, for example, a bisphenol A resin.

[0040] According to one embodiment of the present invention, the inkjet-printed composition may contain 50 to 85 volume% of alumina, for example, 58 to 63 volume%, when the total sum of the ceramic, resin, and pore volumes is 100 volume%. If the alumina content is below the lower limit, the thermal properties may be reduced, which may cause problems in application, and theoretically, the upper limit cannot be exceeded.

[0041] According to one embodiment of the present invention, the inkjet-printed composition may contain 50 to 85 volume% of boron nitride, for example, 58 to 63 volume%, when the total sum of the ceramic, resin, and pore volumes is 100 volume%. If the boron nitride content is below the lower limit, the thermal properties may be reduced, which may cause problems in application, and theoretically, the upper limit content cannot be exceeded.

[0042] According to one embodiment of the present invention, the inkjet-printed composition may contain 50 to 85 volume% of aluminum nitride, for example, 58 to 63 volume%, when the total volume of the ceramic, resin, and pores is 100 volume%. If the aluminum nitride content is below the lower limit, the thermal properties may be reduced, which may cause problems in application, and theoretically, the upper limit cannot be exceeded.

[0043] According to one embodiment of the present invention, the inkjet-printed composition may contain silicon nitride in an amount of 50 to 85 volume%, for example, 58 to 63 volume%, when the total sum of the ceramic, resin, and pore volumes is 100 volume%. If the silicon nitride content is below the lower limit, the thermal properties may be reduced, which may cause problems in application, and theoretically, the upper limit content cannot be exceeded.

[0044] According to one embodiment of the present invention, the inkjet printing composition (ink) may have a viscosity of 1 to 25 cP. If the viscosity is below the lower limit, ink droplets scatter, making it difficult to print a uniform film, and if it exceeds the upper limit, ink droplets are not ejected, making printing impossible.

[0045] According to one embodiment of the present invention, the inkjet printing composition (ink) may further include a solvent. The solvent may include water, ethanol, acetone, DMF (Dimethyl Formamide), p-Xylene, ethylene glycol, dimethylformamide, isopropyl alcohol, DMDG (2-Methoxyethyl ether), etc.

[0046] According to one embodiment of the present invention, the composition ratio of the ceramic, resin, and solvent may include 0.5 to 10 vol% of ceramic and 90 to 99.5 vol% of solvent in the case of ceramic ink, and 0.5 to 40 vol% of resin and 60 to 99.5 vol% of solvent in the case of resin ink. If the upper limit of the composition ratio of the solvent is exceeded, the viscosity of the ink becomes excessively low, causing the ejected droplets to scatter and resulting in uneven printing; if the composition ratio of the solvent is below the lower limit, the viscosity becomes high, making ejection difficult.

[0047] According to one embodiment of the present invention, the inkjet-printed composition may contain pores of 30 volume% or less, 20 volume% or less, 10 volume% or less, or 0 volume% when the total volume of the ceramic, resin, and pores is 100 volume%. The smaller the porosity, the greater the thermal conductivity of the inkjet-printed composition.

[0048] According to one embodiment of the present invention, the thermal conductivity of the inkjet-printed composition may be 2.0 to 18 W / mK.

[0049] According to one embodiment of the present invention, by using the inkjet printing composition (ink), a composite or substrate having a thermal conductivity of 2 W / mk or more, 2.5 W / mk or more, 3 W / mk or more, 3.5 W / mk or more, or 4 W / mk or more can be manufactured.

[0050] Method of manufacturing a substrate using inkjet printing

[0051] According to one embodiment of the present invention, a method for inkjet printing an inkjet printing composition of the present invention is provided, comprising: (S1) a step of manufacturing a ceramic film by printing the ceramic ink by inkjet printing; (S2) a step of manufacturing a composite film by printing the resin ink on the ceramic film by inkjet printing, wherein the resin is 5 to 50 volume%, the ceramic is 50 to 85 volume%, and the pores are 0 to 45 volume%, when the total volume of the ceramic, resin, and pores is 100 volume%; and (S3) a step of manufacturing a film used on a heat dissipation substrate or a substrate by heat treating the composite film.

[0052] The applicant has completed the present invention by discovering that when a substrate is fabricated using an inkjet printing technique with an ink containing a ceramic material and an ink containing a resin, it is possible to produce a substrate with superior reliability compared to a conventional substrate using a ceramic material, particularly a heat dissipation substrate. By utilizing such a heat dissipation substrate, electronic components requiring high-performance heat dissipation substrates, such as printed circuit boards, interposers, HBMs, and GPUs, can be fabricated. The heat dissipation substrate manufactured by the inkjet printing method of the present invention is a substrate capable of effective heat dissipation while compensating for the shortcomings of conventional sintered substrates.

[0053] By using the inkjet printing composition (ink) of the present invention, it is possible to manufacture a substrate or heat sink having uniform thermal conductivity and high thermal conductivity across the entire substrate using the Drop-On-Demand (DOD, a method of printing the required amount of ink where it is needed) method, which is one of the main functions of inkjet printing, without additional processes.

[0054] Inkjet printing is a printing technology that replaces lithography operations, which involve significant material loss, by eliminating the use of hazardous substances and various processes such as processing, exposure, development, and etching. This inkjet printing features a simple process of a single printing and drying step under atmospheric pressure. This technology is used for printing electronic circuit boards due to its advantages, including increased competitiveness in substrate manufacturing, diverse customized designs, printing only necessary areas, environmental friendliness, and improved material utilization efficiency. Ink materials must also possess low viscosity characteristics and long-term reliability required for high-speed ejection. Furthermore, the inkjet method offers better droplet quantitative accuracy, allows for the precise and efficient formation of complex three-dimensional shapes, and enables additive printing, making it possible to produce products with three-dimensional features. Moreover, the ability to produce prototypes for various designs in a short period greatly aids in design finalization prior to mass production, and it is suitable for multi-product, small-batch production methods. Additionally, the inkjet method allows for high-speed coating over large areas.

[0055] In the case of a conventional method for manufacturing a metal printed circuit board in the relevant technical field, a liquid composition mixed with a resin and a filler is applied to a substrate to form an insulating layer in order to form a thermally conductive insulating layer, and the thermally conductive insulating layer is formed by applying it through an S-knife, gravure, flexo, screen, rotary screen, slot die, or micro-gravure coating method.

[0056] These methods are different from the inkjet printing technique used in the present invention, and when a substrate is fabricated using each of these methods, the resulting product has completely different characteristics.

[0057] This reason can be explained by the characteristics of inkjet printing.

[0058] In order to apply the conventional method of coating an insulating layer, a high-viscosity liquid composition must be used. Unlike the conventional coating method, to apply the inkjet printing technique, a low-viscosity liquid composition for inkjet printing, such as that of the present invention, must be used. When this is printed by inkjet printing, an immediate solvent evaporation process occurs, and after printing, spherical ceramic particles (e.g., ceramics such as aluminum nitride) may have a random packing structure or a ceramic network structure. At this time, empty spaces, or pores, exist between the ceramic particles. After printing the ceramic, if the area filled with ceramic is inkjet printed with an inkjet printing resin composition, the resin fills the empty spaces between the ceramic particles without changing the structure of the ceramic network. Since the resin does not disrupt the contact arrangement between the ceramics, the substrate produced by the inkjet printing of the present invention does not experience obstruction of the heat transfer path due to the non-contact arrangement between the ceramic particles (one of alumina, silicon nitride, boron nitride, or aluminum nitride). In other words, it enables continuous heat transfer. In the case of conventional manufacturing methods for metal printed circuit boards, when a liquid composition of resin and filler is mixed to form a thermally conductive insulating layer, a connected heat transfer network of ceramic particles extending from the bottom of the board to the surface is not formed and is interrupted in the middle. This interrupted portion is filled with a resin having low thermal conductivity. Therefore, when manufacturing a substrate using an inkjet printing method, if the pores between the ceramic particles are completely filled with resin, it is possible to manufacture a substrate with a higher thermal conductivity than the conventional substrate manufacturing method.

[0059] The left figure of FIG. 1 and FIG. 2 show examples of heat transfer paths in the internal structure of a substrate or composite formed by inkjet printing of the present invention as described above. This example is for the case where the pore volume is 0. As illustrated in the left figure of FIG. 1 and FIG. 2, the heat transfer path through the ceramic particles can be connected from a low-temperature region (blue region, bottom of the substrate) to a high-temperature region (red region, surface of the substrate) without interruption, so that the effective thermal conductivity value of the composite can be increased.

[0060] On the other hand, in the case of a conventional liquid composition containing high-viscosity resin and fillers (right figure of FIG. 1, this example is one where the pore vol% is 0), the network of fillers is not connected from the bottom of the substrate to the surface, and a break occurs in the middle. The broken parts are filled with resin. Since the resin has a much lower thermal conductivity than the fillers, the liquid composition containing high-viscosity resin and fillers has a lower thermal conductivity than when a low-viscosity liquid inkjet printing composition, as in the present invention, is printed by inkjet printing.

[0061] The right figure of Fig. 1 shows an example of the internal structure of a substrate formed when a layer is applied using a conventional printing method with the conventional high-viscosity composition described above. It is shown that the thermal conduction network by the filler is disconnected and not connected from the bottom to the top layer of the substrate.

[0062] Therefore, when the pore volume% is 0, and the volume% of particles with high thermal conductivity (alumina, silicon nitride, boron nitride, aluminum nitride, etc.) is the same, the thermal conductivity of the substrate produced by the inkjet printing of the present invention can have higher thermal conductivity characteristics than that of a substrate made using a high-viscosity liquid composition containing a conventional resin and filler.

[0063] In addition, since the inkjet printing technique has Drop-On-Demand (DOD) characteristics, it causes a uniform distribution of particles, resulting in excellent reproducibility and uniformity. This allows for the reproduction of a consistent substrate thickness and roughness depending on the printing conditions, while simultaneously enabling easy control of these properties by adjusting the printing conditions. Unlike conventional substrates made using liquid compositions containing high-viscosity resins and fillers, which do not exhibit high reproducibility of thermal conductivity values, the substrate of the present invention exhibits high reproducibility of thermal conductivity characteristics.

[0064] In other words, when the substrate of the present invention is fabricated through inkjet printing, unlike conventional methods, there is no deterioration in thermal conductivity due to the non-uniform distribution of materials, so it can have characteristics of higher thermal conductivity and always a constant thermal conductivity value. In addition, other required characteristics of the substrate (shape, thickness, roughness, etc.) can be easily adjusted, making it possible to apply it to various substrates or devices.

[0065] Substrate (composite) manufactured by inkjet printing

[0066] By using the inkjet printing composition of the present invention, a substrate having a high level of thermal conductivity or a heat sink with good thermal efficiency can be realized using an inkjet printing technique.

[0067] According to one embodiment of the present invention, a printed circuit board can be manufactured by the method of manufacturing a substrate by inkjet printing. A printed circuit board (1; PCB) according to one embodiment of the present invention is illustrated in FIG. 4. The printed circuit board may be composed of, for example, an insulating layer (not shown), a heat sink (2; Heat Sink), a central processing unit (3; Central Processing Unit, CPU), memory (4; Memory), a capacitor (5; Capacitor), a serial port (6; Serial Port), and a keyboard connector (7; KC).

[0068] According to one embodiment of the present invention, a thermally conductive insulating layer of a printed circuit board can be manufactured by the method of manufacturing a substrate by inkjet printing. In addition, a heat sink of a printed circuit board can be manufactured, for example, by the method.

[0069] The structure and operation of the present invention will be described in more detail below through preferred embodiments. However, these are presented as preferred examples of the present invention and should not be interpreted in any way as limiting the present invention.

[0070] Experimental Example 1: Theoretical Analysis of Thermal Conductivity

[0071] The effective thermal conductivity (K) of a composite formed by uniformly mixing three types of components (ceramic, resin, and pores) was calculated using the Lichtenecker formula. The composite refers to a composition (ink) for inkjet printing from which the solvent has been evaporated. The theoretical thermal conductivity of a composite composed of alumina, resin (using the epoxy resin value), and pores (considering the case where the pore volume is 0), and the theoretical thermal conductivity (K) of a composite composed of aluminum nitride, resin (using the epoxy resin value), and pores (considering the case where the pore volume is 0) were calculated using the Lichtenecker formula (see Tables 1 and 2).

[0072] The Lichtenecker formula is the effective thermal conductivity (K or K) of composite materials eff It is a method used to estimate ). The Lichtenecker formula is based on the case where various components within a composite material are homogeneously distributed within the composite. The basic idea is to express the effective thermal conductivity as a function of the thermal conductivity and volume fraction of the individual components. The Lichtenecker formula is frequently used in the technical field because it provides a good balance between simplicity and accuracy.

[0073] The specific formula is as follows.

[0074] <Lichtenecker 공식>

[0075]

[0076] In the above formula,

[0077] i represents a component that makes up a complex.

[0078] φ i represents the volume percentage of component i material, and

[0079] K i represents the thermal conductivity of component i material.

[0080] Generally, in the case of a high-viscosity composite in which ceramic fillers are mixed with resin (a composite composed solely of ceramic and resin without pores), the effective thermal conductivity always has a value smaller than that calculated by the Lichtenecker formula. The primary reason for this smaller value is that the heat transfer network of the fillers is not continuously connected in the direction of heat flow throughout the entire substrate, resulting in points of disconnection. Since these disconnected areas are filled with a resin having low thermal conductivity, the effective thermal conductivity of the composite is lower than that calculated by the Lichtenecker formula. On the other hand, in the case of a ceramic-resin composite formed by inkjet printing (where the pore volume is 0), the network of ceramic particles can be continuously connected in the direction of heat flow. In such cases, the thermal conductivity of the composite can have a value equal to or greater than that calculated by the Lichtenecker formula. The ceramic-resin composite substrate formed by inkjet printing according to the present invention has a thermal conductivity value equal to or greater than that calculated by the Lichtenecker formula.

[0081] The parameters required to calculate the theoretical thermal conductivity using the above formula are listed in Table 1 below. When the pore vol% is 0, the calculated theoretical thermal conductivity values ​​for a composite composed of 60 vol% alumina and 40 vol% resin (epoxy resin) (Example 1) and a composite composed of 60 vol% aluminum nitride and 40 vol% resin are listed in Table 2 below.

[0082] Classification K (W / mK) Alumina 30 Alumina nitride (AlN) 321

[0083] K (W / mK) of composite with 40 vol% epoxy resin Example 1: Alumina 60 vol% Example 2: Alumina nitride (AlN) 60 vol%

[0084] Figure 3 shows a graph of the results calculated using the Lichtenecker formula for the thermal conductivity of each composition according to the vol% of the resin when the vol% of the ceramic is 60. In this case, when the vol% of the resin is less than 40, the vol% of the pores has a value greater than 0. It can be confirmed that using aluminum nitride, a substrate having a thermal conductivity of 16 W / mK or higher can be manufactured when the vol% of the resin (epoxy resin) is 40 vol%.

[0085] Experimental Example 2: Simulation of Thermal Conductivity of a PCB Substrate

[0086] Using Ansys Icepak software, the effect of heat dissipation when using insulating layers of printed circuit boards with different thermal conductivity was analyzed. The specifications for each component of the printed circuit board set for the simulation analysis are shown in Fig. 4. The simulation results are shown in Fig. 5. The temperature is represented as decreasing from red to blue.

[0087] A thermal conductivity of 0.2 W / mK corresponds to the thermal conductivity of the commonly used FR4 (woven glass reinforced epoxy resin) material, and is indicated in Comparative Example 1 in Fig. 5.

[0088] A thermal conductivity of 4 W / mK corresponds to the theoretical thermal conductivity derived from Experimental Example 1 of a composition consisting of 60 vol% alumina and 40 vol% resin according to Example 1, and a thermal conductivity of 17 W / mK corresponds to the theoretical thermal conductivity derived from Experimental Example 1 of a composition consisting of 60 vol% aluminum nitride and 40 vol% resin instead of alumina in Example 2. Here, the calculation was performed using the case of epoxy resin as an example.

[0089] As a result of the simulation, it was confirmed that the heat dissipation effect was superior when using the composition composed of 60 vol% alumina and 40 vol% resin according to Example 1 of the present invention compared to Comparative Example 1 using FR4, and it was confirmed that the heat dissipation effect was much superior when using the composition composed of 60 vol% aluminum nitride and 40 vol% resin instead of alumina in Example 2 of the present invention.

[0090] Preparation Example 1: Preparation of an inkjet-printed composition

[0091] Preparation of the composition of Example 1

[0092] Alumina with 99.9% purity and an average particle size of 400 μm was used as the ceramic ink material. Bisphenol A resin was used as the resin. Di-Methyl Formamide (DMF) and p-Xylene were used as solvents to liquefy the materials, thereby preparing an alumina ink (alumina (ceramic) + DMF (solvent)) and a resin ink (bisphenol A resin + p-Xylene (solvent)). The solvent composition ratio was 10 vol% alumina, 90 vol% DMF, 20 vol% resin, and 80 vol% p-Xylene. The alumina ink was printed to produce an alumina film with a volume ratio of alumina to pores of 60:40. Subsequently, the resin ink was printed onto the alumina film to fill the pores with resin, thereby producing a composite film with an alumina:resin ratio of 60:40 (volume ratio). The above membrane was heat-treated at 180°C for 6 hours to prepare the final composition. (Fig. 6: When the resin volume is 40%) The volume ratio of pores in the final composite membrane composition was 0 volume%.

[0093] Preparation of the composition of Example 3

[0094] A composition was prepared in the same manner as in Example 1, except that the final composite membrane composition was prepared such that the bisphenol A resin was 30 vol%, the alumina was 60 vol%, and the pore vol% was 10 vol%. (Fig. 6: Case where the resin vol% is 30%)

[0095] Preparation of the composition of Example 4

[0096] A composition was prepared in the same manner as in Example 1, except that the final composite membrane composition was prepared such that the bisphenol A resin was 20 vol%, the alumina was 60 vol%, and the pore vol% was 20 vol%. (Fig. 6: Case where the resin vol% is 20%)

[0097] Preparation of the composition of Example 5

[0098] A composition was prepared in the same manner as in Example 1, except that the final composite membrane composition was prepared such that the bisphenol A resin was 10 vol%, the alumina was 60 vol%, and the pore vol% was 30 vol%. (Fig. 6: Case where the resin vol% is 10%)

[0099] Experimental Example 3: Preparation of an Inkjet-Printed Substrate

[0100] When particles are printed using inkjet printing, a film with a uniform particle distribution can be produced by finely controlling the ink droplets ejected from each nozzle. At this time, as alumina particles with high thermal conductivity accumulate, they form a heat transfer network that is continuously connected from the bottom to the top of the film. However, in the conventional composition manufacturing method where alumina particles are inserted into the resin as a filler, the network of alumina particles connecting the upper and lower layers of the film may become disconnected. A resin with low thermal conductivity occupies this disconnected portion. Therefore, it was expected that a ceramic-resin composition (where the vol% of the pores is 0) produced by the inkjet printing method of the present invention would have a higher thermal conductivity value than a composition made by inserting a filler into the resin. To verify whether the composition produced by the inkjet printing of the present invention has a high thermal conductivity value, the thermal conductivity of substrates produced by inkjet printing, such as the compositions of Examples 1 and 3 to 5 above, was measured.

[0101] The results of measuring the thermal conductivity of substrates prepared with the compositions of Example 1 and Examples 3 to 5 are shown as black dots in Fig. 6. The experimental value of the thermal conductivity of the substrate prepared by inkjet printing with the composition of Example 1 was 4 W / mK, which was confirmed to be in close agreement with the theoretical value (red dots) based on the Lichtenecker formula. It was confirmed that the thermal conductivity of Examples 3 to 5 was slightly higher than the theoretical value (Example 3 was measured at 3.42 W / mK, Example 4 at 2.90 W / mK, and Example 5 at 2.28 W / mK).

[0102] That is, when a substrate is manufactured by inkjet printing using the inkjet printing composition according to the present invention, it can be presumed that the ceramic heat transfer network in the internal structure of the substrate is arranged in a ceramic network structure having a value equal to or greater than the value predicted by the Lichtenecker formula. Therefore, when manufacturing a substrate or heat sink by an inkjet printing method, it was confirmed that a substrate or heat sink having a greater thermal conductivity than a substrate made using a high-viscosity liquid composition mixed with resin and filler can be manufactured when the vol% of the pores is 0 to 30 vol%.

[0103] Although an embodiment of the present invention has been described above, this specification is not necessarily limited to such embodiment. Those skilled in the art may modify and change the present invention in various ways by adding, changing, deleting, or adding components, etc., without departing from the spirit of the invention as described in the claims, and such modifications and changes are also to be included within the scope of the rights of the present invention.

[0104] [Explanation of the symbol]

[0105] 1 : Printed Circuit Board (PCB)

[0106] 2 : Heat Sink

[0107] 3 : Central Processing Unit (CPU)

[0108] 4 : Memory

[0109] 5 : Capacitor

[0110] 6 : Serial Port

[0111] 7 : Keyboard Connector (Keyboard Connector, KC)

Claims

1. A ceramic ink comprising one of alumina, silicon nitride, boron nitride, and aluminum nitride; and Inkjet printing composition containing resin.

2. In Paragraph 1, The above resin is a thermosetting resin, Inkjet printing composition, 3. In Paragraph 2, The above thermosetting resin comprises one of polyacrylates resin, epoxy resin, phenolic resin, polyamides resin, polyimides resin, unsaturated polyesters resin, polyphenylene ether resin (PPE), polyphenylenesulfides resin, cyanate ester resin, and benzocyclobutene (BCB). Composition for inkjet printing.

4. In Paragraph 1, The ceramic ink and resin ink each have a viscosity of 1 to 25 cP, Composition for inkjet printing.

5. In Paragraph 1, further containing a solvent, Composition for inkjet printing.

6. An inkjet-printed composition manufactured by printing an inkjet printing composition according to any one of claims 1 to 5 using inkjet printing, wherein A composite membrane comprising 5 to 50 volume% of the resin, wherein the total volume of the ceramic, resin, and pores is 100 volume%. Inkjet printed composition.

7. In Paragraph 6, Comprising 50 to 85 volume% of the above ceramic, Inkjet printed composition.

8. In Paragraph 6, Containing 50 volume% or less of the above pores, Inkjet printed composition.

9. In Paragraph 6, The thermal conductivity of the above inkjet-printed composition is 2.0 to 18 W / mK, Inkjet printed composition.

10. A method for inkjet printing an inkjet printing composition according to any one of claims 1 to 5, wherein (S1) A step of manufacturing a ceramic film by printing the ceramic ink using inkjet printing; (S2) A step of manufacturing a composite film by printing the resin ink onto the ceramic film by inkjet printing, wherein the resin comprises 5 to 50 volume%, the ceramic comprises 50 to 85 volume%, and the pores comprise 0 to 30 volume%, when the total volume of the ceramic and resin is 100 volume%; and (S3) A step of heat-treating the composite film to manufacture a film used in a heat sink or substrate; comprising How to print using an inkjet printer.

11. A printed circuit board manufactured in accordance with Paragraph 10.

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