Low-dielectric materials for electronics

Abstract

The present disclosure relates to build-up films comprising pure silica zeolite materials, methods of preparing pure silica zeolites and electronic devices comprising the build-up films.

Description

Attorney Docket No. 039621.01516LOW-DIELECTRIC MATERIALS FOR ELECTRONICSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 737,523 filed on December 20, 2024, the contents of which is incorporated herein by reference in its entirety.BACKGROUND

[0002] Advances in telecommunications necessitates the development of electronic materials that are capable of operating at ever-increasing frequencies. For example, 5G or fifth generation technologies operate in the GHz regime. However, at high frequencies, electrical circuits are plagued by the resistance of conductors and the capacitance of the insulating substrates. Therefore, current hardware must be optimized for compatibility with the high-frequency ranges used in 5G networks to provide faster, more reliable, and cheaper communication.

[0003] Smaller delays for electrical signals can be achieved by lowering the dielectric constant (K) of the insulating materials used in printed circuit board substrates. The preferred dielectric material for use in these electronics should also possess high thermal and chemical stability, high mechanical strength, and low thermal expansion, thereby allowing for effective thermal and thermomechanical management. Such materials largely comprise particles of inorganic particles such as SiCh, embedded in a thermoset polymer-based matrix.SUMMARY OF THE DISCLOSURE

[0004] The present disclosure provides compositions that comprise an inorganic particle and a thermally cross-linkable resin, wherein the inorganic particle has a dielectric constant (K) value, for example, below that of silicon dioxide at a frequency of 10 GHz, but maintaining the (thermo) mechanical strength of silicon dioxide. While the lowering of dielectric constant can be achieved by introducing porosity in silicon dioxide (porous silicon dioxide), such a filler adversely affects the thermomechanical properties of the dielectric layer (in particular the coefficient of thermal expansion).

[0005] In another embodiment, the composition comprises a 95%-100% pure silica zeolite material and a thermally cross-linkable resin.

[0006] In some embodiments, the silica zeolite material is selected from sodalite, Linde Type A (LTA), AST, and DDR-type zeolites. In some embodiments, the silica zeolite material contains 5% or less of sodium ions or aluminate impurities. In some embodiments, the silicaAttorney Docket No. 039621.01215 zeolite material is hydrophobic. In some embodiments, the silica zeolite material has a negative thermal expansion coefficient. In some embodiments, the silica zeolite material is microporous.

[0007] In some embodiments, the composition is suitable for use as a build-up film. In other aspects, the build-up film comprises 40-80 wt% pure silica zeolite and 10-50 wt% of the thermoset polymer. In some embodiments, the build-up film has a dielectric constant (K) value of 2.5-3.9 at a frequency of 10 GHz (e.g., lower than a similar film with identical loading of silicon dioxide particles in the same matrix material).

[0008] A second aspect of the present disclosure is directed to a method of preparing a pure silica zeolite material from fumed silica.

[0009] Another aspect of the present disclosure is directed to a method of forming a pure silica zeolite filler.

[0010] Further aspects of the present disclosure are directed to an electronic device, comprising an electronic component and the build-up film on a surface of the electronic component.

[0011] The subject matter described herein is capable of other and different embodiments and its several details are capable of modifications in various respects, all without departing from the claimed subject matter. The invention is further illustrated by the following drawings, detailed description, and examples.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is X-Ray Diffraction (XRD) patterns and 3-D structures of pure silica zeolite MEL powder by drying MEL nanoparticle suspension; (a)-(h) represent XRD of resulting products from increasing synthesis time.

[0013] FIG. 2 is a simulation of the correlation of loss-factor for epoxy-silica composite with variable silica fraction according to a simple Looyenga mixing model. The model gives an approximate Df value of composite of interest (70 wt% silica ~ 56 vol% silica) as a half of the Df of epoxy polymer. The Df value is dominated by the Df value of epoxy polymer as opposed to the Df value of silica which is at least 1-2 orders of magnitude lower and can therefore be neglected.

[0014] FIG. 3 is a simulation of the correlation of dielectric constant Dk for epoxy-silica composite with variable silica fraction according to a simple Looyenga mixing model. The model gives an approximate Dk value of composite of interest (70 wt% silica ~ 56 vol% silica) as an average of the Dk value of the epoxy polymer and the Dk value of the silica as the values are comparable.Attorney Docket No. 039621.01215

[0015] FIG. 4 is a 3-D structural representation of pure silica sodalite powder from experimental synthesis by treating fumed silica with sodium hydroxide.

[0016] FIG. 5 is XRD patterns of sodalite powder from DFT calculation and from experimental analysis of as-made material.

[0017] FIG. 6 is scanning electron microscope (SEM) images of as-made pure silica sodalite.

[0018] FIG. 7 is Fourier-tranform infrared spectroscopy (FTIR) of fumed silica precursor vs FTIR of as-made sodalite.

[0019] FIG. 8 is an SEM image of pure silica sodalite after slow heat treatment, exhibiting a 3-D rhobohedral structure.

[0020] FIG. 9 is FTIR of pure silica sodalite before and after slow heat treatment.

[0021] FIG. 10 is XRD patterns of as-made sodalite, sodalite after fast heat treatment and after slow heat treatment.

[0022] FIG. 11 is an SEM image of a composition comprising 12 vol% pure silica sodalite with rhobohedral structure, 37.4 vol% SiCh and 50.7% epoxy polymer and hardener after seeding.

[0023] FIG. 12 provides dielectric measurements of films comprising pure silica sodalite at 10 GHz.

[0024] FIG. 13 shows build-up films prepared by mixing epoxy polymer, hardner, SiCh and pure silica sodalite. As no effort was made to control the particle size and / or functionalize the silica sodalite presented herein, it was not possible to prepare build-up films comprising only of pure silica sodalite without silica particles and therefore for the purpose of demonstration, various ratios of the sodalite with respect to silica was used to generate the data, keeping the overall loading of the particles constant for comparison.

[0025] FIG. 14 shows experimental measurements of dielectric constant Dk for build-up films.DETAILED DESCRIPTION

[0026] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which the subject matter herein belongs.

[0027] In some aspects, the present disclosure is directed to inorganic materials with low K values. These materials are desirable for high-frequency electronics.Attorney Docket No. 039621.01215

[0028] In addition to having low dielectric constants, the desired materials should be chemically and thermally stable, and air-stable to enable ease of processing. They should also display low dielectric loss and low thermal expansion at high frequencies.

[0029] Being hydrophobic is another important advantage for these low-dielectric materials, because water or any product from water decomposition can increase dielectric constant and increase dielectric loss that are both highly undesirable.

[0030] In order to meet these requirements, one solution is to combine a 1OW-K inorganic component, such as silica particles or fibers, with an organic polymer to produce a composite that takes advantage of the best qualities of both materials.

[0031] The dielectric properties of these composites can also be enhanced through a number of strategies. For example, more C-C and C-F bonds can be incorporated into the polymer to minimize polarizability and hence K. Additionally, porosity can be engineered into the composite to lower its density, thereby reducing the number of dipoles.

[0032] Methods to reduce the dielectric constant of composites often involves trade-offs with other desirable qualities. For example, the use of a larger volume fraction of the organic component relative to the inorganic component may lead to a lower dielectric constant for the composite but could at the same time produce deleterious thermal expansion effects and poor mechanical properties. Therefore, to further reduce the dielectric constant of printed circuit board composites, the inventors have developed materials with the desirable qualities of fumed silica while also possessing low dielectric constants (<4.0 when measured at 10 GHz).

[0033] FIG. 2 presents XRD patterns and 3-D structures of pure silica zeolite MEL powder from increasing synthesis time. Such exemplified materials, synthesized via drying MEL nanoparticle suspensions, display different morphologies given different amounts of synthesis time.

[0034] The present disclosure is directed to materials with chemical formulas of SiCh. These materials have specific crystal structures and are prepared via specific synthesis procedures.Exemplary materials are pure silica compositions of mineral sodalite in cubic and rhombohedral structures. Such materials are selected after a systematic examination across structures and compositions using high-level density functional theory (DFT) calculations. These materials are hydrophobic and can exclude water due to their specific structures and compositions.Compositions

[0035] The present disclosure provides compositions comprising an inorganic particle; and a thermally cross-linkable resin, wherein the inorganic particle has a dielectric constant (K) valueAttorney Docket No. 039621.01215 at below 4.0 at a frequency and has an average particle size of 0.1-100 m (e.g., 10-lOOpm) and is hydrophobic. In other aspects, the inorganic particle has a dielectric constant (K) value at a frequency of 10 GHz below a similar film comprising wholy of silica particles in the same polymer matrix and is hydrophobic.

[0036] In another aspect, for an application in build-up films, the inorganic particle has an average particle size between 100-500 nm and is functionalized suitably for dispersion in the polymer matrix, with cutoff of particle size less than 3 j m.

[0037] In some aspects, the inorganic particle is a 95%-100% pure silica zeolite material. In some aspects, the pure silica zeolite material is at least one of sodalite, LTA, AST, and DDR- type zeolites. In some aspects, the pure silica zeolite material contains 5% or less of sodium ions or aluminate impurities. In some aspects, the pure silica zeolite material has a negative thermal expansion coefficient.

[0038] In other aspects, the thermally cross-linkable resin is a thermoset polymer or an epoxy resin such as any of the epoxy resins described in U.S. Pub. No. 2023 / 134713, which is incorporated by reference herein in its entirety.

[0039] In other aspects, the composition is suitable for use is a build-up film. In some aspects, the build-up film has a K value of less than 2.5 to 3.9 at a frequency of 10 GHz. In some aspects, the build-up film comprises 30-90 wt% pure silica zeolite.

[0040] In other aspects, the build-up film comprises 50-85 wt% pure silica zeolite. In some aspects, the build-up film comprises 60-80 wt% pure silica zeolite. In some aspects, the buildup film comprises 15-20 wt% of the thermoset polymer. In some aspects, curing temperatures of 100-180 °C for 15 min to 3 h. In other aspects, the methods for curing can be any of those described in U.S. Pub. No. 2023 / 134713, which is incorporated by reference herein in its entirety.

[0041] In some aspects, the pure silica zeolite material has a framework density in a range of 14-19 Si atoms per 1000 A3and a ring size in a range of 6-14 A.Methods

[0042] In some aspects, the present disclosure is directed to a method for preparing a pure silica zeolite. For example, in one aspect, the method of preparing a pure silica zeolite material, comprises stirring a mixture comprising fumed silica; transferring the mixture to a hydrothermal vessel; and heating the mixture until a 95%-100% pure silica zeolite material is formed.Attorney Docket No. 039621.01215

[0043] In other aspects, the method further comprises rinsing the silica zeolite material with deionized water. In particular aspects, the rinsing is conducted until the mixture has a pH of 7. In other aspects, the mixture further comprises sodium hydroxide and ethylene glycol.

[0044] In some aspects, the mixure comprses a ratio of the fumed silica to the sodium hydroxide is 2: 1. In other aspects, the mixure comprises a ratio of fumed silica to ethylene glycol of 1 :20.

[0045] In some aspects, the stirring is conducted for at least 24 hours. In other aspects, the mixture is heated at a temperature of 160 °C. In other aspects, the mixture is heated for three weeks.

[0046] In some aspects, the pure silica zeolite material is sodalite.

[0047] In other aspects, the disclosure provides a method of forming a pure silica zeolite filler, the method comprising: heat treating pure silica zeolite on a template under a gas flow. In some aspects, the gas is O2 or N2. In other aspects, the temperature of the heating is increased to 700 °C at a predetermined rate. In other aspects, the temperature is held at first temperature of 350 °C for a predetermined period of time during the temperature increase to 700°C. In other aspects, the temperature is held at a second temperature of 400 °C for a predetermined period of time during the temperature increase to 700°C.

[0048] In other aspects, the template comprises carbon. In other aspects, the method further comprises removing the template when the temperature reaches 700 °C.

[0049] In other aspects, wherein the pure silica zeolite filler is sodalite.Films and Electronic Devices

[0050] In other aspects, the disclosure provides a film comprising a cured material of any of the compositions described herein. In general, curing of epoxy resins may be achieved by reacting an epoxy with itself or by forming a copolymer with polyfunctional curatives or hardeners. In specific aspects, any method of curing described in U.S. Pub. No. 2023 / 134713, which is incorporated by reference herein in its entirety, may be used.

[0051] In other aspects, the disclosure provides an electronic device comprising an electronic component; and any of the films described herein on a surface of the electronic component. In one aspect, the electronic device is a computer. In another aspect, the electronic component is a circuit board. In specific aspects, the electrical component and / or electronic device is that described in U.S. Pub. No. 2023 / 134713, which is incorporated by reference herein in its entirety, may be used.Attorney Docket No. 039621.01215

[0052] The products and methods of the present disclosure will be better understood in connection with the synthetic schemes that are described in the working examples that illustrate non-limiting methods by which the structures of the disclosure may be prepared.EXAMPLESExample 1: Synthesis of pure silica sodalite with cubic structure.

[0053] Step 1 : Stirring a mixture of fumed silica (2 equiv.) and sodium hydroxide (1 equiv.) in ethylene glycol (40 equiv.) for 24 hours;Step 2: Transfering the resulting mixture to 23 mL hydrothermal vessel and reacting at 160 °C for 3 weeks; andStep 3: Rinsing the product from step 2 with deionized water until pH = 7.

[0054] The resulting pure silica sodalite is phase pure, as demonstrated by FIG. 5. As-made sodalite has cubic structure, with diameter of 10-50 m, as calculated by referencing the scale bar on the SEM images of FIG. 6. FTIR (FIG. 7) confirms the formation of product, with presence of leftover templating material.

[0055] As-made pure silica sodalite is predicted by DFT calculation to have K = 3.25.Example 2: Phase transformation of pure silica sodalite from cubic structure to rhobohedral structure during prolonged heat treatment under O2.

[0056] Prolonged heat treatment under O2 causes a phase transition (see above). Such 3-D rhobohedral structure of pure silica sodalite after slow heat treatment was determined by SEM image, as shown by FIG. 8. Pure silica sodalite with rhobohedral structure is predicted by DFT calculation to have K = 3.45. Differences in the heating speed and gas atmosphere resulted in different phase transformation properties, such as 3-D morphologies and the amounts of impurities during the process of deposition.

[0057] Experimental observations show that faster heating and heating under N2 repress phase transformation; however, this will cause more carbon to be deposited.

[0058] A comparison between the FTIR spectra of pure silica sodalite before and after slow heat treatment is shown in FIG. 9; a comparison between XRD patterns is shown in FIG. 10.Attorney Docket No. 039621.01215Example 3: Preparation of build-up films and measurements of K values.

[0059] A film was bladed with a composition consisting of 750 mg SiCh, 216 mg pure silica sodalite with rhobohedral structure, 191 mg epoxy polymer and 235 mg hardener and cured to obtain a thin film with thickness of about 90 m, as shown in FIG. 11.

[0060] Similarly, six trials of build-up films were prepared by blading and curing the epoxy polymer, hardner, SiCh and pure silica sodalite. Tables summarizing the compositions of the build-up films are shown in FIG. 13.

[0061] The dielectric measurements (K values) of films comprising pure silica sodalite at 10 GHz are plotted, as shown in FIG. 12. The K values of a film comprising only silica sodalite particles in the polymer matrix (without silica) can be extrapolated by plotting dielectric measurement against pure silica sodalite content to 100% silica-sodalite content. There is a clear trend that increasingly exchanging a portion of the silica particles in the composition against silica sodalite leads to lower Dk, therefore validating the calculated lower dielectric constant of silica sodalite.

[0062] FIG. 14 shows the experimental measured Dk values for build-up films in FIG. 13. The K values of a film comprising only silica sodalite particles in the polymer matrix (without silica) can be extrapolated by plotting dielectric measurement against pure silica sodalite content to 100% silica-sodalite content. There is a clear trend that increasingly exchanging a portion of the silica particles in the composition against silica sodalite leads to lower Dk, therefore validating the calculated lower dielectric constant of silica sodalite.

[0063] Although the disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present disclosure as defined by the appended claims.

Claims

Attorney Docket No. 039621.01215Claims1. A composition, comprising: an inorganic particle; and a thermally cross-linkable resin, wherein the inorganic particle has a dielectric constant (K) value below 4.0 at a frequency of 10 GHz and an average particle size of 0.1-100 m and is hydrophobic.

2. The composition of claim 1, wherein the inorganic particle is a 95%-100% pure silica zeolite material.

3. The composition of claim 2, wherein the pure silica zeolite material is at least one of sodalite, LTA, AST, and DDR-type zeolites.

4. The composition of claim 2, wherein the pure silica zeolite material is sodalite.

5. The composition of claim 2, wherein the pure silica zeolite material contains 5% or less of sodium ions or aluminate impurities.

6. The composition of claim 2, wherein the pure silica zeolite material has a negative thermal expansion coefficient.

7. The composition of claim 2, wherein the inorganic particle has an average particle size between 100-500 nm and is functionalized suitably for dispersion in the polymer matrix, with cutoff of particle size less than 3 gm.

8. The composition of claim 1, wherein the dielectric constant (K) value of the inorganic particle is lower than the K value of a silicon dioxide particle at a frequency of 10 GHz, wherein the silicon dioxide particle, such as a non-porous silicon dioxide particle, is present in a composition comprising the silicon dioxide particle and the thermally cross-linkable resin of claim 1.

9. The composition of any one of claims 1-9, wherein the thermally cross-linkable resin is a thermoset polymer.Attorney Docket No. 039621.0121510. The composition of any one of claims 9, wherein the inorganic particle is functionalized and dispersed within the thermoset polymer.

11. The composition of claim 9 or 10, wherein the thermoset polymer is an epoxy polymer.

12. The composition of any one of claims 1-11, wherein the composition is suitable for use as a build-up film.

13. The composition of claim 12, wherein the build-up film has a K value of 2.5-3.9 at a frequency of 10 GHz.The composition of claim 12, wherein the build-up film comprises 30-90 wt% pure silica zeolite.

15. The composition of claim 14, wherein the build-up film comprises 50-85 wt% pure silica zeolite.The composition of claim 15, wherein the build-up film comprises 60-80 wt% pure silica zeolite.

17. The composition of claim 12, wherein the build-up film comprises 15-20 wt% of the thermoset polymer.

18. The composition of any one of claims 1-17, wherein the pure silica zeolite material has a framework density in a range of 14-19 Si atoms per 1000 A3and a ring size in a range of 6- 14 A.

19. A method of preparing a pure silica zeolite material, the method comprising: stirring a mixture comprising fumed silica; transferring the mixture to a hydrothermal vessel; and heating the mixture until a 95%-100% pure silica zeolite material is formed.

20. The method of claim 19, further comprising rinsing the silica zeolite material with deionized water.Attorney Docket No. 039621.0121521. The method of claim 20, wherein the rinsing is conducted until the mixture has a pH of 7.

22. The method of any one of claims 19-21, wherein the mixture further comprises sodium hydroxide and ethylene glycol.

23. The method of claim 22, wherein a ratio of the fumed silica to the sodium hydroxide is 2: 1.

24. The method of claim 22, wherein a ratio of the fumed silica to the ethylene glycol is 1 :20.

25. The method of any one of claims 19-24, wherein the stirring is conducted for at least 24 hours.

26. The method of any one of claims 19-25, wherein the mixture is heated at a temperature of 160 °C.

27. The method of any one of claims 19-26, wherein the mixture is heated for three weeks.

28. The method of any one of claims 19-27, wherein the pure silica zeolite material is sodalite.

29. A method of forming a pure silica zeolite filler, the method comprising: heat treating pure silica zeolite on a template under a gas flow.

30. The method of claim 29, wherein the gas is O2.

31. The method of claim 29, wherein the gas is N2.

32. The method of any one of claims 29-31, wherein the temperature of the heating is increased to 700 °C at a predetermined rate.Attorney Docket No. 039621.0121533. The method of any one of claims 29-32, wherein the temperature is held at first temperature of 350 °C for a predetermined period of time during the temperature increase to 700°C.

34. The method of any one of claims 29-33, wherein the temperature is held at a second temperature of 400 °C for a predetermined period of time during the temperature increase to 700°C.

35. The method of any one of claims 29-34, wherein the template comprises carbon.

36. The method of any one of claims 29-35, further comprising removing the template when the temperature reaches 700 °C.

37. The method of any one of claims 29-36, wherein the pure silica zeolite filler is sodalite.

38. A film comprising a cured material of the composition of any one of claims 1-18.

39. An electronic device comprising: an electronic component; and the film of claim 36 on a surface of the electronic component.

Images