Direct write dual-curing gasket

Abstract

A composition for producing a filler, comprising a plurality of ceramic particles, a liquid oxirane monomer, an ultraviolet initiator that absorbs ultraviolet rays, and a thermal initiator.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 356,731, filed on June 29, 2022, which is hereby incorporated by reference in its entirety.

Background Art

[0002] The present disclosure relates to photo - and thermosetting composite materials, and more specifically, to photo - and thermosetting composite materials for direct - write semiconductor applications.

[0003] In a conventional printed circuit board, electronic components or chips are mounted on the surface of the bottom - most wiring layer. An insulating layer and the top - most wiring layer are laminated on the chip, and via - holes are formed for electrical connection between the wiring layer and the chip.

[0004] In response to the requirements for higher functionality and miniaturization of electronic devices, the recent technological trend is towards higher density and miniaturization of electronic components. For this reason, there is an increasing demand for miniaturization of printed circuit boards capable of mounting electronic components at high density. Therefore, the development of multilayer circuit boards that electrically connect wiring layers or wiring formed on different layers and electrical components via via - holes is in progress. Multilayer circuit boards reduce the wiring for connecting electronic components to each other, increase the surface area of the printed circuit board by wiring at high density, and provide excellent electrical characteristics.

Summary of the Invention

[0005] According to some embodiments, it is a composition for manufacturing a filler, comprising a plurality of ceramic particles, a liquid oxirane monomer, an ultraviolet initiator that absorbs ultraviolet light, and a thermal initiator.

[0006] According to other embodiments, the chip-embedded printed circuit board includes a cavity in the printed circuit board, a chip in the cavity of the printed circuit board, and a gap filler in the gap in the cavity for sealing the chip in the printed circuit board. The gap filler includes an oxirane-based polymer and ceramic particles, and its coefficient of thermal expansion is about 10 to about 150 parts per million per degree Celsius.

[0007] However, according to other embodiments, a method of screening a combination of initiators for curing a polymer includes providing a first composition including a liquid oxirane monomer and an ultraviolet initiator. The method further includes exposing the first composition to ultraviolet light having a wavelength absorbed by the ultraviolet initiator to initiate polymerization of a first polymer and measuring the enthalpy released by the first polymer. The method also includes providing a second composition including a liquid oxirane monomer, an ultraviolet initiator, and a thermal initiator, and exposing the second composition to ultraviolet light having a wavelength absorbed by the ultraviolet initiator to initiate polymerization of a second polymer. The method includes measuring the enthalpy released by the second polymer formed by the second composition and comparing the enthalpy of the first polymer with the enthalpy of the second polymer. The method includes determining, based on the comparison, whether the UV initiator and the thermal initiator inhibit each other.

[0008] Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the present disclosure are described in detail herein and considered a part of the claimed disclosure. Refer to the description and drawings to better understand the present disclosure with its advantages and features.

[0009] To understand the present disclosure more fully, reference is now made to the following brief description taken in conjunction with the accompanying drawings and detailed description. Like reference numerals represent like parts.

Brief Description of the Drawings

[0010]

Figure 1A

[0011]

Figure 1B

[0012]

Figure 2

[0013]

Figure 3A

[0014]

Figure 3B

[0015]

Figure 3C

[0016]

Figure 3D

[0017]

Figure 4

[0018]

Figure 5-1

Figure 5-2

[0019]

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0020] As described above, a conventional printed circuit board has laminated chips mounted on its surface together with metal-filled vias that connect the upper and lower wiring layers. However, creating such via holes involves complex processing steps.

[0021] Using chips embedded in a printed circuit board eliminates the need for via wiring, reducing processing costs and complexity. A cavity is formed in the printed circuit board, a chip is placed in the cavity, and a material is used to fill the gap between the chip and the printed circuit board.

[0022] Norland Electronic Adhesive 121 (NEA 121) is a mercapto - ester / benzophenone composition and is an adhesive for temporary attachment, filling, sealing, insulating protection coating of precision products, and prevention of unauthorized opening. However, the drawback of NEA 121 as a gap filler for embedding chips in printed circuit boards is that its viscosity is too low (about 300 centipoises), resulting in minimal shear thinning, that is, due to the low viscosity and minimal shear thinning, the capillary tubes on the side walls of the joints are wetted, which is not preferable, and material loss is caused by the gaps at the bottom of the device construction. Furthermore, due to the CTE of NEA 121, peeling and cracking of the interconnections may occur. Creative Materials 119 - 48 (CM 119 - 48) is a screen - printable flexible UV - curable dielectric coating that has also been used as a gasket in similar applications. However, this material has an unfavorably high viscosity (about 150,000 centipoises), the material maintains its shape during dispensing, the finish is rough, and it becomes difficult to print silver on it.

[0023] Accordingly, this specification describes a method of embedding chips in a printed circuit board that eliminates gap filler compositions and via wiring, thereby reducing processing costs and device complexity. The composition is printable for direct - write applications and has thermal expansion characteristics similar to those of printed conductive inks used to form interconnections, which is an important step in creating a more robust printed structure. The composition and materials enable the printing of multilayer - printed microwave devices, particularly in embodiments where the gap from the chip to the printed circuit board is filled, by improving the robustness of the printed interconnections.

[0024] The gap filler composition includes a liquid oxirane monomer, a UV initiator, and a thermal initiator, which are cured by a dual-curing mechanism that includes both UV light and heat thereby. By the dual-curing mechanism, the material can be first cured with ultraviolet light to be fixed on the substrate, and then post-treated by heating to increase the degree of cure and material strength and reduce the CTE. A lower CTE is desirable, and to prevent peeling of the printed interconnections, the composition further includes inorganic particles and a heat-resistant organic matrix that provides a preferred shear-thinning effect. Since a syringe is not required for the composition, it can be used in a conventional direct-write manufacturing apparatus. The dual-curing composition enables a post-treatment step that simultaneously promotes monomer conversion and provides the lowest possible CTE. To use the composition as a gap filler, a cavity is formed in a printed circuit board, a chip is placed in the cavity, and a direct-write dual-curing (thermal and UV) composite ink is placed to fill the gap in the cavity between the chip and the circuit board and provide an embedded die encapsulated with a printable gasket material. An interposer is placed over the cavity to provide electrical connection to the chip.

[0025] The gap filler described herein is formed by first providing a composition that includes a liquid oxirane monomer, a UV initiator that absorbs ultraviolet light, a thermal initiator, and a plurality of ceramic particles. The monomer is liquid, and since solvents cause undesirable shrinkage, no additional solvent is necessary. In one or more embodiments, the composition is solvent-free (or contains no solvent), or contains less than 1 wt% solvent, less than 5 wt% solvent, or less than 10 wt% solvent.

[0026] The monomer is an oxirane monomer, which polymerizes by a ring-opening mechanism with less strain compared to linear monomers such as acrylates. The oxirane monomer is polymerized via a cationic pathway, is not inhibited by oxygen, and has improved stability as opposed to acrylates. In some embodiments, the composition is free of (or does not contain) acrylate monomers. In some embodiments, the composition comprises less than 1 wt% acrylate monomer, less than 5 wt% acrylate monomer, or less than 10 wt% acrylate monomer.

[0027] The monomers used in the composition have a boiling point above 130 °C in some embodiments, such that the monomers do not boil before causing thermal curing of the monomers, which occurs at about 110 °C. In other embodiments, the monomers have a boiling point above 150 °C. However, in embodiments, the monomers have a boiling point of about 130 °C to about 300 °C.

[0028] The monomers used in the composition are further of low viscosity, e.g., less than 17 centipoise in some embodiments, such that a large amount of ceramic particles can be combined in the composition to reduce the CTE. In other embodiments, the monomers have a viscosity of less than 10 centipoise, less than 5 centipoise, or less than 2 centipoise. However, in embodiments, the monomers have a viscosity of about 1 to about 5,000 centipoise.

[0029] The monomers used in the composition are oxirane monomers, which are monomers containing one or more oxirane structures. In some embodiments, the oxirane monomer contains two oxirane structures. In other embodiments, the oxirane monomer contains three oxirane structures. In some embodiments, the oxirane structure monomer is a symmetric compound. In other embodiments, the oxirane monomer contains one or more oxirane structures and one or more ethers. In one or more embodiments, the oxirane monomer contains two oxirane structures and two ether structures. However, in some embodiments, the oxirane monomer contains three oxirane structures and three ether structures. Further, in other embodiments, the oxirane monomer does not contain an aromatic structure.

[0030] Non-limiting examples of oxirane monomers include butanediol diglycidyl ether, trimethylolpropane triglycidyl ether, neopentyl glycol diglycidyl ether, tris(4-hydroxyphenyl)methane triglycidyl ether, resorcinol diglycidyl ether, bisphenol-A diglycidyl ether-based resins, novolac epoxy resins, or any combination thereof.

[0031] One non-limiting example of an oxirane monomer has the following structure.

Chemical formula

[0032] Another non-limiting example of an oxirane monomer has the following structure.

Chemical formula

[0033] The ultraviolet initiator in the composition absorbs ultraviolet light with a wavelength of from about 200 nanometers to about 400 nanometers. In one or more embodiments, the ultraviolet initiator absorbs ultraviolet light with a wavelength of from about 260 nanometers to about 360 nanometers. In some embodiments, the ultraviolet initiator is a hexafluorophosphate. In one or more embodiments, the ultraviolet initiator is a hexafluorophosphate having the following structure. [Chemical formula]

[0034] The composition further comprises a thermal initiator. The thermal initiator has a thermal activation temperature above 110 °C, acts as a Lewis acid to initiate cationic polymerization, can post-treat the heat-treated material, and further increases the degree of curing. In one or more embodiments, the thermal activation temperature is above 120 °C or above 130 °C. In one or more embodiments, the thermal initiator is a Lewis acid. A non-limiting example of the thermal initiator has the following structure. [Chemical formula]

[0035] Due to the dual curing mechanism, the filler is first cured by ultraviolet light and then by heat. When ultraviolet light is absorbed, the energy of the ultraviolet initiator generates free radicals that react with the monomers, initiating polymerization and ultraviolet curing. The ultraviolet initiator can cure the gap filler by using ultraviolet light from an ultraviolet source such as a mercury lamp or a light-emitting diode lamp. Then, when heat is absorbed, the catalyst is converted to HBF4, a strong Lewis acid. Subsequently, a proton from the Lewis acid can be added to the oxygen atom of the oxirane monomer. This then causes cationic polymerization to occur between the oxonium ion and all available oxirane monomers. The composition further includes an inert inorganic filler that is a plurality of ceramic particles. In some embodiments, the ceramic particles are high aspect ratio particles such as boron nitride. Since the aspect ratio of the particles is high in a low-viscosity liquid, when shear is applied, they align in the direction of flow, resulting in a shear-thinning effect. This shear-thinning results in smooth and high-resolution printing. The ceramic particles have thermal conductivity, are opaque, and do not absorb ultraviolet light, so they do not interfere with curing by ultraviolet light.

[0036] According to one or more embodiments, the ceramic particles are hexagonal boron nitride particles. In some embodiments, the ceramic particles have an aspect ratio of from about 2:1 to about 30:1. In other embodiments, the ceramic particles have an aspect ratio of from about 10:1 to about 20:1. According to one or more embodiments, the ceramic particles have an average diameter of from about 0.5 to about 1.2 micrometers. In other embodiments, the ceramic particles have an average diameter of from about 0.8 to about 1.0 micrometers.

[0037] According to other embodiments, the ceramic particles do not have a high aspect ratio and are spherical in shape, such as glass spheres. In embodiments, the glass spheres have a diameter of from about 0.5 to about 20 micrometers. In other embodiments, the glass spheres have a diameter of from about 2 to about 10 micrometers.

[0038] In one or more embodiments, the ceramic particles are included in the gap filler composition in an amount of about 10 to about 80 weight percent. In other embodiments, the ceramic particles are included in the gap filler composition in an amount of about 15 to about 60 weight percent.

[0039] When polymerized by ultraviolet light and heat, the resulting dual-cured gap filler includes a polymer matrix. In some embodiments, the polymer of the polymer matrix is an oxirane polymer. However, in other embodiments, the polymer matrix is a polymer formed from butanediol diglycidyl ether, trimethylolpropane triglycidyl ether, neopentyl glycol diglycidyl ether, tris(4-hydroxyphenyl)methane triglycidyl ether, resorcinol diglycidyl ether, bisphenol-A diglycidyl ether-based resin, novolac epoxy resin, or any combination thereof.

[0040] The use of ceramic particles can reduce the CTE of the composite material. In one or more embodiments, the CTE of the cured composition is about 10 to about 150 parts per million per degree Celsius. In other embodiments, the CTE of the cured composition is about 40 to about 100 parts per million per degree Celsius.

[0041] In an embodiment, the composition is used to form a chip-embedded printed circuit board. FIG. 1A is a top view of a chip-embedded printed circuit board 100. FIG. 1B is a side cross-sectional view of FIG. 1A. The chip-embedded printed circuit board 100 includes a substrate 102 that is a printed circuit board. The substrate 102 that is a printed circuit board has a laminated structure of a conductive layer (such as copper) and an insulating layer. The printed circuit board can be single-sided (e.g., one copper layer), double-sided (two copper layers on both sides of one substrate layer), or multilayer (outer and inner copper layers alternating with layers of insulator).

[0042] To embed chip 104 into substrate 102, cavity 110 is formed in substrate 102. Cavity 110 is formed by a processing method according to the material forming substrate 102. Cavity 110 is formed, for example, by etching, pressing, drilling, laser processing, or a combination thereof. The formed cavity 110 has dimensions of length 112 and width 114 (Figure 1A) that are larger than the chip 104 to be embedded. In some embodiments, the height 116 (or thickness, Figure 1B) of cavity 110 is substantially the same as the height (or thickness) of chip 104, so that the surface of the embedded chip 104 is substantially flush with the surface of substrate 102. Further, in other embodiments, the height 116 (or thickness) of cavity 110 is smaller than the height (or thickness) of chip 104, and gap filler 106 is arranged or laminated so as to function as an increment up to chip 104. After forming cavity 110 in substrate 102, chip 104 is inserted into cavity 110. Chip 104 is also called a die or an electronic component. Chip 104 is a resistor or a capacitor.

[0043] Chip-embedded circuit board 100 includes gap filler 106 in the gap in cavity 110 to form a gasket for sealing chip 104 in substrate 102. Filler 106 is a thixotropic material. Chip-embedded printed circuit board 100 further includes a plurality of interposers 108 printed on gap filler 106 to provide an electrical connection between chip 104 and substrate 102. Interposer 108 includes, for example, silver.

[0044] FIG. 2 is a side cross-sectional view showing a method of embedding chip 204 in printed circuit board 202. The method includes forming cavity 210 in printed circuit board 202 and placing chip 204 in the cavity in printed circuit board 202. The method further includes placing gap filler 206 in the gap in cavity 210 to seal chip 204 in the cavity of printed circuit board 202. The method further includes forming an interposer 208 on gap filler 206 to provide an electrical connection between chip 204 and printed circuit board 202.

[0045] Gap filler 206 is injected into the gap around chip 204 by syringe 220 in some embodiments. Any method can be used to place gap filler 206 in cavity 210. The gap filler is irradiated with ultraviolet light to cure the composition. Heat is then applied to further cure the composition. According to one or more embodiments, the ultraviolet light is irradiated for a time, such as about 2 to about 4 minutes, and then the heat is irradiated for a time, such as about 90 to about 150 minutes. The time for each curing step varies depending on many factors, such as the monomers used, the combination of initiators, and the specific application.

[0046] The thixotropic properties of gap filler 206 mean that shear thinning is time-dependent. Gap filler 206 is thick or viscous under static conditions or low shear, but becomes less viscous and flows when shear stress is applied. In some embodiments, the viscosity of gap filler 206 at a shear rate of 5s -1 is greater than the viscosity of gap filler 206 at a shear rate of 50s -1 According to one or more embodiments, gap filler 206 has a viscosity of about 10,000 to about 50,000 cps at a shear rate of 5s -1 and has a viscosity of about 1,000 to about 10,000 cps at a shear rate of 50s -1 According to other embodiments, gap filler 206 has a viscosity of about 10,000 to about 50,000 cps at a shear rate of 5s -1has a viscosity of about 15,000 to about 30,000 cps at a shear rate of, and 50 s -1 has a viscosity of about 2,500 to about 7,500 cps at a shear rate of.

[0047] Due to the dynamic viscosity of the filler 206, the filler 206 can simultaneously receive shear stress and flow into the gap between the chip and the printed circuit board, providing a smooth surface, so it is an ideal electronic gap filler for embedding the chip into the printed circuit board. By including ceramic particles (e.g., boron nitride), a strong thixotropic effect is brought about in the filler. Due to the thixotropic shear thinning effect, the viscosity of the filler decreases when shear is applied for extrusion from the syringe, and then returns to a high viscosity when the shear is removed, leaving a high-resolution smooth pattern. In contrast, the surface of commercially available electronic fillers is not preferred because it has a high viscosity and a rough finish that cannot be printed on the surface, or has a low viscosity, minimal shear thinning, capillary wetting of the side walls of the joint, and losses in the gap at the bottom of the device. In addition to the above gap filling applications, the dynamic viscosity of the fillers described herein is also suitable for other electronic applications, including any gap filling electronic applications, or other electronic applications where a dielectric material is required to provide an inclined or rising surface.

[0048] Also described herein is a method for screening combinations of initiators for curing polymers. Since thermal initiators and UV initiators can interact to reduce each other's reactivity, an assay has been developed to evaluate the reactivity of various combinations of UV initiators and thermal initiators. The photo DSC assay measures the reactivity of the UV initiator in the presence of various thermal initiators. After incubating at the target temperature for a certain time (e.g., 1 minute at 40 °C), the uncured gap filler material is exposed to ultraviolet light for a certain time (e.g., 3 minutes). The enthalpy (watts / gram) is measured as a function of time (minutes).

[0049] First, measure the controlled light DSC spectrum of a monomer containing a single initiator (e.g., only a UV initiator or only a thermal initiator). The measured enthalpy indicates the formation of bonds between monomers induced by the single initiator, i.e., polymerization. Measure the area under the curve to determine the reaction enthalpy.

[0050] Next, measure the photo DSC spectrum of a monomer combined with two initiators, e.g., a UV initiator and a thermal initiator. The resulting enthalpy again indicates the formation of bonds between monomers induced by the combination of initiators, i.e., polymerization. Measure the area under the curve to determine the reaction enthalpy.

[0051] Compare the reaction enthalpy measured with a single initiator to the reaction enthalpy measured with the combination of initiators. Then, determine whether the reaction enthalpies are similar or not. If they are similar, the inhibitory interaction between the initiators on monomer conversion is minimized, resulting in favorable outcomes. However, if the reaction enthalpies are not similar and the sample with the combined inhibitors is lower than the control, there is an inhibitory interaction between the initiators, which is not favorable.

[0052] According to one or more embodiments, a method for screening a combination of initiators includes providing a first composition comprising a liquid oxirane monomer and a single initiator, the single initiator being an ultraviolet (UV) initiator. The method includes exposing the first composition to UV light at a wavelength absorbed by the UV initiator to initiate polymerization of a first polymer. The method further includes measuring the enthalpy released by the polymer formed by the first composition. The method further includes providing a second composition comprising a liquid oxirane monomer, a UV initiator, and a thermal initiator. The method includes exposing the second composition to UV light at a wavelength absorbed by the UV initiator to initiate polymerization of a first polymer. The method further includes measuring the enthalpy released by a second polymer formed by the second composition. Next, the method includes comparing the enthalpy of the first polymer with the enthalpy of the second polymer and determining, based on the comparison, whether the UV initiator and the thermal initiator inhibit each other.

[0053] In some embodiments, the method further includes incubating the composition at a temperature of about 30°C to about 50°C before exposing the composition to UV light. In other embodiments, the method further includes exposing the composition to UV light for about 3 minutes to about 5 minutes.

Example

[0054] Example 1: Photo-DSC and DSC Assays of Combinations of UV and Thermal Initiators Since thermal initiators and UV initiators can interact to reduce each other's reactivity, assays were performed to evaluate the reactivity of various combinations of UV and thermal initiators.

[0055] Photo-DSC was used to measure the reactivity of a UV initiator in the presence of various thermal initiators. After incubating at 40°C for 1 minute, the uncured gap filler material was exposed to UVA radiation for 3 minutes. FIG. 3A is the photo-DSC spectrum of the gap filler material after UV photocuring with a combination of UV initiator #1 and thermal initiators #3 and #4. [Chemistry]

[0056] Figure 3B is the photo-DSC spectrum of the gap filler material after UV photocuring by combining UV initiator #2 (bottom) with thermal initiators #3 and #4 (top). [Chemistry] The enthalpy (watts / gram) was measured as a function of time (minutes). As shown in FIGS. 3A and 3B, the combination of UV initiator #1 and thermal initiator #3 showed the maximum enthalpy release, which was consistent with the maximum degree of polymerization for this combination.

[0057] Using a conventional DSC, the reactivity of the thermal initiator in the presence of various UV initiators was measured. Figure 3C is the differential scanning calorimetry (DSC) spectrum of the gap filler material after thermosetting by combining thermal initiator #3 (top) with UV initiators #1 and #2 (top). Figure 3D is the differential scanning calorimetry (DSC) spectrum of the gap filler material after thermosetting by combining thermal initiator #4 with UV initiators #1 and #2. The uncured material was tested up to a temperature of 300 °C with a temperature increase of 20 °C per minute. The enthalpy (watts / gram) was measured as a function of temperature (degrees Celsius). As shown in FIGS. 3C and 3D, thermal initiator #1 resulted in the strongest enthalpy release with both UV initiators, which was also consistent with the maximum degree of polymerization.

[0058] Example 2: DSC assay of monomers The combination of UV initiator #1 and thermal initiator #3 was used to investigate the degree of cure and thermal events of various monomers using DSC. Figure 4 shows the DSC spectra of a gap filler containing monomers #1 - 5. The relative heat flow (watts / gram) was measured as a function of temperature (degrees Celsius) increasing by 20 degrees per minute up to 300 degrees. The dotted trace shows each sample before curing, and the solid trace shows the sample after curing at 125 °C for 16 hours. By measuring before and after curing, the residual enthalpy could be compared to the initial enthalpy, which indicated the degree of cure (the amount of monomer reacted to form the polymer). As shown in Figure 4, certain monomers showed a higher degree of cure than others. These monomers then became the preferred monomers going forward as they had fully reacted.

[0059] Example 3: FT - IR assay of the degree of cure of various monomers Fourier transform infrared (FT - IR) spectroscopy was used to study the degree of cure and thermal events of various monomers. As shown in Figure 5, FT - IR was performed on each sample after curing, with the dotted trace showing the spectrum before curing and the solid trace showing the spectrum after curing. These spectra showed a band for unreacted oxirane groups at 3000 cm -1 in the uncured samples and a band for hydroxide groups at 3750 cm -1 in the cured material, indicating that the targeted polymerization had occurred.

[0060] Example 4: CTE assay of ceramics Various amounts of ceramics such as boron nitride and hollow glass spheres were added to the gap filler composition along with the indicated monomers and polymerized using a combination of UV initiator #1 and thermal initiator #3. Monomer #4 had a viscosity of 17 centipoise. Monomer #5 had a viscosity of 150 centipoise. Figure 6 shows the coefficient of thermal expansion (CTE) of gap fillers containing various amounts of boron nitride and glass sphere particles. The linear CTE (parts per million per degree Celsius) was measured as a function of the weight percent of the ceramic. The ceramic was mixed to match the CTE of the printed conductor. As shown in Figure 6, increasing the amount of ceramic particles decreased the CTE of the overall composite and brought it closer to the CTE of the printed conductor ink.

[0061] Compositions, methods, and articles can alternatively include, consist of, or consist essentially of any suitable materials, steps, or components disclosed herein. Compositions, methods, and articles can additionally or alternatively be formulated so that materials (or species), steps, or components that are not otherwise necessary for the achievement of the functions or objectives of the compositions, methods, and articles are absent or substantially absent.

[0062] All ranges disclosed herein include endpoints, and the endpoints can be combined independently of each other (e.g., the range of "up to 25 wt%, or more specifically from 5 wt% to 20 wt%" includes the endpoints and all intermediate values of ranges such as "from 5 wt% to 25 wt%"). "Combination" includes blends, mixtures, alloys, reaction products, etc. Terms such as "first", "second", etc. do not indicate any order, quantity, or importance, but are used to distinguish one element from another. The terms "a", "an", and "the" do not mean a limitation of quantity, but are to be construed as covering both the singular and the plural unless otherwise indicated herein or clearly contradicted by the context. "Or" means "and / or" unless otherwise specified. As used herein, terms such as "comprising", "including", "having", "containing", "involving", etc. are to be understood as non-limiting, i.e., meaning that "including" is not limited, unless otherwise specified. "About" or "approximately" as used herein means including the recited value and within an acceptable deviation range of a particular value determined by one of ordinary skill in the art, taking into account the error associated with the measurement in question and the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "about" may mean within one or more standard deviations, or within ±10% or ±5% of the recited value. The use of any and all examples, or illustrative language (e.g., "such as") is merely intended to better clarify the invention and does not impose a limitation on the scope of the invention unless otherwise claimed. No representation in this specification should be construed as indicating that any non-claimed element is essential for the practice of the invention as used herein.

[0063] Throughout this specification, when reference is made to "aspects", "embodiments", etc., it means that the specific elements described in connection with an embodiment are included in at least one embodiment described herein, and may or may not be present in other embodiments. Further, it should be understood that the elements described can be combined in any suitable manner in various embodiments. "Combinations thereof" is open-ended and includes any combination that arbitrarily includes at least one of the recited components or characteristics together with similar or equivalent components or characteristics.

[0064] Various embodiments of the present invention are described herein with reference to the accompanying drawings. Alternative embodiments can be devised without departing from the scope of the present invention. In the following description and drawings, various connections and positional relationships (e.g., above, below, adjacent, etc.) between elements are described. However, as will be understood by those skilled in the art, many of the positional relationships described herein are not orientation-dependent, provided that the described functions are maintained even if the orientation is changed. These connections and / or positional relationships can be direct or indirect, unless otherwise specifically specified, and the present invention is not intended to be limited in this regard. Thus, a physical connection can refer to a direct or indirect connection, and a positional relationship between entities can be a direct or indirect positional relationship. As an example of an indirect positional relationship, a reference in this description to forming layer "A" above layer "B" includes a situation where one or more intermediate layers (e.g., layer "C") are between layer "A" and layer "B", provided that the relevant characteristics and functions of layer "A" and layer "B" are not substantially changed by the intermediate layer(s).

[0065] The following definitions and abbreviations should be used in the interpretation of the claims and the specification. As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "contains," or "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, mixture, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or other elements inherent to such composition, mixture, process, method, article, or apparatus.

[0066] Furthermore, the term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" should not necessarily be construed as preferred or superior to other embodiments or designs. The terms "at least one" and "one or more" are understood to include any integer greater than or equal to one, i.e., one, two, three, four, etc. The term "a plurality" is understood to include any integer greater than or equal to two, i.e., two, three, four, five, etc. The term "connected" can include both indirect and direct "connections."

[0067] References in the specification to "one embodiment," "an embodiment," "exemplary embodiment," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may or may not include that particular feature, structure, or characteristic. Also, such phrases do not necessarily refer to the same embodiment. Further, it is presented that when a particular feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0068] For the following description, the terms "upper", "lower", "right", "left", "vertical", "horizontal", "uppermost", "lowermost", and derivatives thereof, shall relate to the structures and methods described as oriented in the drawings. The terms "lying on", "on", "above", "positioned above", or "positioned on" mean that a first element such as a first structure is present on a second element such as a second structure, and intervening elements such as an interface structure can be present between the first element and the second element. The term "direct contact" means that a first element such as a first structure and a second element such as a second structure are connected without any intervening conductive, insulating, or semiconductor layer at the interface of the two elements.

[0069] The terms "about", "substantially", "nearly", and variations thereof are intended to include the degree of error associated with a particular quantity measurement based on the equipment available at the time of filing. For example, "about" can include a range of ±8% or 5% or 2% of a given value.

[0070] The flowcharts and block diagrams in the figures illustrate possible embodiments of the manufacturing and / or operating methods according to various embodiments of the present invention. The various functions / operations of the method are indicated by blocks in the flowchart. In some alternative embodiments, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may in fact be executed substantially simultaneously, or the blocks may sometimes be executed in the reverse order depending on the functions involved.

[0071] All means or steps plus function elements in the following claims are intended to cover any structure, material, or acts for performing the functions in combination with other claimed elements specifically claimed, including any structure, material, or acts for performing the functions in combination with other claimed elements. The description of the invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. Embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

[0072] Although the preferred embodiments of the present invention have been described, it should be understood by those skilled in the art that various improvements and enhancements within the scope of the following claims can be made, both now and in the future. These claims should be construed to maintain the proper protection for the present invention as first described.

Claims

1. A composition for manufacturing a filler, comprising: a plurality of ceramic particles, a liquid oxirane monomer, an ultraviolet initiator that absorbs ultraviolet light, and a thermal initiator.

2. The composition according to claim 1, wherein the plurality of ceramic particles are boron nitride particles.

3. The composition according to claim 1, wherein the plurality of ceramic particles are glass spheres.

4. The composition according to claim 1, wherein the ultraviolet initiator has the following structure. 【Chemical Formula 1】

5. The composition according to claim 4, wherein the thermal initiator has the following structure. 【Chemical 2】

6. The composition according to claim 5, wherein the oxirane monomer has the following structure. [Chemical 3]

7. The composition according to claim 1, wherein the composition does not contain a solvent.

8. A chip-embedded printed circuit board, comprising: a cavity in the printed circuit board, a chip in the cavity of the printed circuit board, and a gap filler in the gap in the cavity for sealing the chip in the printed circuit board, the gap filler comprising an oxirane-based polymer and ceramic particles and having a coefficient of thermal expansion of about 10 to about 150 parts per million per degree Celsius.

9. A method for screening a combination of initiators for curing a polymer, comprising: providing a first composition comprising a liquid oxirane monomer and an ultraviolet initiator; exposing the first composition to ultraviolet light having a wavelength absorbed by the ultraviolet initiator to initiate polymerization of a first polymer; measuring the enthalpy released by the first polymer; providing a second composition comprising a liquid oxirane monomer, the ultraviolet initiator, and a thermal initiator; exposing the second composition to ultraviolet light having the wavelength absorbed by the ultraviolet initiator to initiate polymerization of a second polymer; measuring the enthalpy released by the second polymer formed by the second composition; comparing the enthalpy of the first polymer with the enthalpy of the second polymer; and determining, based on the comparison, whether the ultraviolet initiator and the thermal initiator inhibit each other.

Images