Patent Application
20250091030
This invention relates to getters specifically engineered to adsorb both polar and non-polar gases, as well as organic compounds, emitted from electronic packages, devices, and modules. More specifically, it pertains to multi-phase hierarchical porous nanostructured polymer composite-based getters designed to scavenge a wide range of polar and non-polar gases and organic compounds, irrespective of their polarity, molecular size, or surface energy properties.
The reliability of electronic devices is often influenced by the packaging materials used, such as polymers, epoxies, adhesives, and thermal interface materials. These materials can release various gases, including H2, N2, O2, CO, CO2, CH4, and volatile organic compounds, as well as various particles, with the emission levels determined by material properties and operating conditions. Elevated temperatures can cause the thermal decomposition of polymers, releasing small molecules such as H2, CO, CO2, and CH4, along with organic compounds. For example, silicone-based materials may emit CH4 and CO2, organic compounds (e.g., methanol, ethanol, isopropanol), and hydrocarbons (e.g., methane (CH4), ethane, propane), while epoxy resins can release CO and CO2, hydrocarbons (e.g., toluene, benzene, xylene), and organic compounds (e.g., methanol, ethanol, benzyl alcohol). Moisture interacting with adhesives or flux residues can generate H2 through hydrolysis, while oxidative degradation can produce CO, CO2, and occasionally SO2 when sulfur-containing components are present. Additionally, organic compounds such as toluene, xylene, and acetone are often outgassed from adhesives, and RF/MW absorbents can break down into CO, CO2, and H2 at elevated temperatures. Entrapped gases like N2, O2, and CO2 and some particles may also be gradually released during operation, especially under vacuum or thermal cycling conditions.
The release of multi-gas emissions (e.g., H2, N2, O2, CO, CO2, and CH4), along with various organic compounds (e.g., hydrocarbons (HCs) and volatile organic compounds (VOCs)) of different sizes and polarities, can significantly compromise the reliability of electronic packages. Compounds like CO2 and organic acids (produced from decomposed organic compounds) can react with moisture to form acidic by-products, leading to corrosion of sensitive metals such as copper and silver in wiring and interconnects. Hydrogen can react with metal oxides, reducing protective passivation layers and making the metals more susceptible to embrittlement and further corrosion. Organic compounds (HCs and VOCs) may condense on critical surfaces, including optical components, MEMS devices, or circuit boards, resulting in contamination that disrupts functionality. Moisture can increase internal humidity, leading to higher leakage currents and potential dielectric breakdown in sensitive components. Outgassed chemicals can degrade adhesives, coatings, and polymer-based components, weakening their mechanical strength and adhesion. Additionally, condensed organic residues on electronic components can reduce light transmission and impair optical performance. Organic residues on component surfaces can also diminish heat dissipation efficiency.
Non-evaporable getters (NEGs) are a well-established solution for controlling outgassing, especially in vacuum systems and analytical instruments. These getters are typically composed of single-phase reactive metals, such as titanium (Ti), zirconium (Zr), tantalum (Ta), vanadium (V), and alloys like Zr—V—Fe, Zr—Al, Zr—Ti—V, and Ti—V—Cr. NEGs primarily operate through chemisorption, where gases chemically react with the getter material to form stable compounds, and sometimes through physisorption on the getter's surface. Zeolite-based getters are another effective solution, particularly for managing outgassing in microelectronic and electronic packages by adsorbing moisture (H2O) or both moisture and hydrogen (H2). However, both types of getters are typically limited in scope, targeting specific emission types such as hydrogen and moisture, or combinations of these gases.
Both types of getters, optimized for a limited number of polar or non-polar gases, are ineffective at capturing organic compounds, even in small amounts. While a getter might adsorb some small organic compounds (molecular size <1 nm, and weight <100 g/mol), such as in environments where formaldehyde or acetone are a primary concern; it may still struggle to address larger organic compounds with molecular weights >100 g/mol and molecular sizes >1 nm. For example, sensitive electronic packages often release small organic compounds due to adhesives, coatings, or solvents. However, if a getter is only capable of adsorbing small organic compounds, it may fail in applications where larger organic compounds or aggregates dominate. Therefore, a multi-functional getter capable of adsorbing both polar and non-polar gases, organic compounds across a broad spectrum of molecular sizes is more desirable.
The functional limitations of both types of getters arise from mismatched surface energies relative to many outgassed gases and organic compounds. Zeolites typically exhibit surface energies between 50 and 70 mJ/m2, categorizing them as high-surface-energy materials. Similarly, NEGs have surface energies in the range of 50-60 mJ/m2, classifying them as medium-to-high-surface-energy materials. In comparison, polar gases like H2O, CO, CO2, SO2, and NH3 typically have surface energies between 50 and 72 mJ/m2, while non-polar gases like H2, O2, N2, and CH4 fall within the lower range of 18-25 mJ/m2. For organic compounds, polar compounds such as acetone, ethanol, isopropanol, and methanol exhibit surface energies between 28 and 45 mJ/m2, whereas non-polar organic compounds like toluene, benzene, xylene, propane, and butane range from 20-30 mJ/m2.
Given the surface energy ranges of zeolites (50-70 mJ/m2) and NEGs (50-60 mJ/m2), these getters are well-suited for adsorbing high-surface-energy polar gases such as H2O and CO2. However, they are less effective at capturing low-surface-energy non-polar gases like H2, O2, N2, and CH4. While metal oxide doping (e.g., PdO for hydrogen) can enhance selectivity for specific gases, it underscores a significant limitation: current getters cannot comprehensively adsorb the full spectrum of outgassed gases and organic compounds. This limitation arises because the getters' surface energies are substantially higher than those of many non-polar gases and organic compounds. Moreover, relying on a single-surface-energy material restricts versatility, making it difficult to capture a diverse mix of gases and organic compounds without additional enhancements or dopants.
Effectively adsorbing non-polar gases like hydrogen (H2), oxygen (O2), and nitrogen (N2) requires low surface energy levels in the range of 18-25 mJ/m2. These low-to-medium surface energy levels enable adsorption primarily through non-specific van der Waals interactions, the dominant mechanism for capturing non-polar gases. In contrast, polar gases such as moisture (H2O), carbon dioxide (CO2), and ammonia (NH3) require medium-to-high surface energies (40-70 mJ/m2) for effective adsorption, relying on stronger polar interactions. A getter with a uniform surface energy—whether low (20-30 mJ/m2), medium (30-40 mJ/m2), or high (40-70 mJ/m2)—is typically limited in function, as it can only effectively adsorb a narrow range of gases. To overcome this limitation, there is a need for getters with varying surface energy structures. Such designs would enable the adsorption of a broader range of outgassed gases and organic compounds, regardless of their polarity, molecular size, and surface energy level.
This invention presents a multi-phase hierarchical porous nanostructured polymer composite with a precisely engineered hybrid surface energy profile. The composite integrates multiple levels of porosity, including micropores and mesopores, each optimized for selective gas adsorption. Hydrophilic micropores with high surface energy are designed to adsorb polar gases. Hydrophobic micropores with low-to-medium surface energy are specialized for capturing non-polar gases and small organic compounds (size <1 nm, weight <100 g/mol). Hydrophobic mesopores are tailored for larger non-polar gases and organic compounds (size >1 nm, weight >100 g/mol), offering expanded pore spaces that enhance adsorption and storage, complementing the micropores' capacity for efficient gas separation and retention.
The multi-phase hierarchical porous nanostructured material of this invention is capable of adsorbing a wide range of gases, including hydrocarbons and organic compounds, irrespective of their polarity, molecular size, or surface energy differences. Each phase within the composite features a distinct porous domain with a tailored surface energy, collectively spanning a comprehensive surface energy range of 20-70 mJ/m2. The integration of microporous and mesoporous nanostructures enables the adsorption of outgassed species across diverse polarities and molecular sizes. By incorporating materials with varied surface energy profiles, ranging from 20-70 mJ/m2, the design effectively targets both polar and non-polar gases, as well as organic compounds.
The terms “invention,” “the invention,” “this invention,” and “present invention” broadly refer to all subject matter disclosed herein, including the claims. Similarly, the terms “polymer composite” and “getter material” are used interchangeably, as are “getter assembly” and “getter.” The term “organic compounds” encompasses both polar and non-polar hydrocarbons (HCs) as well as volatile organic compounds. Additionally, “multiple gases” and “multi-gas” are synonymous, as are “emissions” and “outgassed species.” The terms “high surface energy/low surface energy” and “hydrophilicity/hydrophobicity” are also used interchangeably. Statements using these terms do not limit or restrict the subject matter described or the scope of the claims. The claims themselves define the invention's embodiments, while this summary serves as a high-level overview of key concepts, which are further elaborated in the Detailed Description section. This summary is not intended to specify essential features or limit the scope of the claims, which should be interpreted in light of the entire specification, including the accompanying drawings and individual claims.
The design and development of polymer composite materials for scavenging outgases in electronic packages can be tailored by combining carefully selected phases, each contributing specific functional attributes for the adsorption of targeted gases and organic compounds. A nanoparticle material with a microporous structure, such as zeolites, provides high surface energy domains that are effective for adsorbing polar gases like H2O and CO2. In contrast, a nanoparticle material with a mesoporous structure, such as mesoporous silica or alumina, offers larger pore spaces, enhancing the composite's capacity to adsorb non-polar gases and organic compounds. A polymer matrix with low-to-medium surface energy serves as the binding medium for these nanoparticles while optimizing the overall surface energy profile of the composite. This matrix not only ensures mechanical stability and flexibility but also supports the physisorption of non-polar gases such as H2, O2, N2, and various organic compounds.
The multi-phase hierarchical porous nanostructured composite comprises four phases: (1) a hydrophilic microporous nanostructure, (2) a hydrophobic microporous nanostructure, (3) a hydrophobic mesoporous structure, and (4) a polymer matrix with low-to-medium surface energy. The hierarchical porous nanostructure is characterized by multi-level porosity, achieved by embedding microporous and mesoporous nanoparticles into the polymer matrix. This structure maximizes the active surface area and adsorption site density, ensuring that each phase is specialized for targeted adsorption without interference from other phases.
The first-phase material can be selected from aluminosilicates, such as 3A, 4A, 5A, and 13X zeolites, zeolite X, zeolite Y, zeolite A, and natural zeolites. These materials have micropore sizes ranging from 0.3 nm to 2.0 nm and surface energies between 50-70 mJ/m2, making them effective for adsorbing polar gases and organic compounds. The second-phase material may include modified zeolites like silicalite-1, ZSM-5, and beta zeolite, which have high Si/Al ratios, surface energies of 30-60 mJ/m2, and reduced hydrophilicity. These zeolites balance mesoporosity and hydrophobicity, making them suitable for adsorbing non-polar gases and organic compounds. The third-phase material, with surface energies ranging from 20-80 mJ/m2, can be selected from hydrophobic metal-organic frameworks (MOFs), functionalized mesoporous silica (e.g., SBA-15 and MCM-41), activated carbon aerogels, hydrophobic silica aerogels, mesoporous graphene aerogels, and mesoporous alumina. The surface energy of these materials can be modified through functionalization with alkyl, fluorinated, or silane groups. The fourth-phase material, with surface energies ranging from 18-70 mJ/m2, can be selected from polymers such as polyvinyl alcohol, silicone RTV, polyimide, epoxy resins, polycarbonate, and polytetrafluoroethylene. This polymer material serves as the matrix to embed the nanoparticles from the first three phases.
In one embodiment, the gettering material integrates both microporous and mesoporous nanoparticles within a tailored polymer matrix, which consists of quaternary or ternary phases. In another embodiment, the microporous nanoparticles are hydrophilic and act as molecular sieves for the adsorption of small polar multi-gases and organic compounds (with molecular sizes <1 nm and molecular weights <100 g/mol). In a further embodiment, the mesoporous nanoparticles are hydrophobic, providing a large surface area and ample void spaces to adsorb larger non-polar multi-gases and organic compounds (with molecular sizes >1 nm and molecular weights >100 g/mol). Additionally, the microporous nanoparticles may also be hydrophobic, functioning as molecular sieves for the adsorption of non-polar gases and organic compounds of smaller sizes (<1 nm and <100 g/mol).
The composite integrates nanostructured micropores and mesopores with varying pore sizes to address diverse adsorption needs. In one embodiment, hydrophilic microporous nanoparticles (less than 100 nm in size with pore dimensions from 0.3 nm to 1 nm) serve as molecular sieves for polar multi-gases and small organic compounds (with sizes <1 nm and molecular weights <100 g/mol). In another embodiment, hydrophobic microporous nanoparticles (also less than 100 nm) function as molecular sieves for non-polar multi-gases and non-polar organic compounds. A further embodiment incorporates hydrophobic mesoporous nanoparticles (less than 100 nm in size with pore dimensions ranging from 2 nm to 50 nm), which efficiently adsorb larger non-polar molecules (with sizes >1 nm and molecular weights >100 g/mol).
The composite also includes a polymer matrix that may be hydrophobic (e.g., polyimide, silicone RTV, polycarbonate, or polytetrafluoroethylene) or hydrophilic (e.g., polyvinyl alcohol or epoxy resins). The selected polymer matrix ensures mechanical integrity, thermal stability, and compatibility with the embedded nanoparticles over a wide temperature range (e.g., −200° C. to 350° C. for PI, −55° C. to 200° C. for silicone RTV, and −50° C. to 150° C. for polyvinyl alcohol and −40° C. to 200° C. for high-temperature epoxy resins). While the polymer matrix provides some adsorption capacity for both polar and non-polar gases and organic compounds, its primary role is to bind the composite together and enhance its durability under varying operational conditions.
To develop a polymer composite capable of adsorbing a broad range of polar and non-polar gases and organic compounds, regardless of their polarities or molecular sizes or surface energy, the design must incorporate hierarchical porosity and optimized surface energy. For seamless integration of all phases within the polymer matrix, the surface energies of the materials in each phase must be precisely tailored. For applications involving small polar gas emissions, the composite is enhanced with hydrophilic microporous nanoparticles with surface energies between 35-45 mJ/m2. For environments dominated by small non-polar gases and organic compounds, hydrophobic microporous nanoparticles with surface energies in the range of 35-50 mJ/m2 are utilized. For balanced emissions of both polar and non-polar gases and organic compounds, the composite is designed with an optimal surface energy of 35-50 mJ/m2. For scenarios dominated by polar multi-gas emissions and organic compounds, the composite incorporates materials achieving a surface energy of 45-60 mJ/m2 to ensure effective adsorption across diverse gases.
To enable the polymer composite-based getter to adsorb a wide variety of gases, a multi-phase nanomaterial integration approach is adopted. This multi-phase nanomaterial may consist of 2, 3, or 4 components, each representing an adsorption capacity for specific gas types. Each phase features a distinct porous domain with tailored surface energy, spanning a comprehensive surface energy range of 20-70 mJ/m2. Some phases are optimized for polar gases, while others are tailored for non-polar gases or larger organic compounds molecules. This multi-phase architecture ensures efficient capture of a broad spectrum of gases and organic compounds, maximizing adsorption capacity and selectivity without interference among the adsorbed species.
In one embodiment, the adsorbed gases are polar gases, such as H2O, CO, CO2, NH3, and SO2. In another embodiment, the adsorbed gases are non-polar gases, such as H2, O2, N2, and CH4. Yet another embodiment targets polar organic compounds, such as methanol, acetone, ethanol, and formaldehyde. Further embodiments focus on non-polar organic compounds, such as benzene, toluene, xylene, hexane, ethylene, and propane.
The polymer composite can be formulated with quaternary or ternary compositions based on the specific application. In one embodiment, the composite consists of 20-60 wt % hydrophilic microporous nanoparticles for polar-dominant gas and organic compounds absorption, 20-60 wt % mesoporous nanoparticles for adsorbing larger non-polar gases (with sizes >1 nm and molecular weights >100 g/mol), and 20-50 wt % polymers. In another embodiment, it includes 20-60 wt % hydrophobic microporous nanoparticles for adsorbing small non-polar gases and organic compounds (with sizes <1 nm and molecular weights <100 g/mol), 20-60 wt % mesoporous nanoparticles for adsorbing larger non-polar gases, and 20-50 wt % polymers. A further embodiment combines 20-60 wt % hydrophilic microporous nanoparticles for polar gases, 20-60 wt % hydrophobic microporous nanoparticles for non-polar gases and organic compounds with small sizes, and 20-50 wt % polymers.
The polymer composite can also be designed with binary compositions. In one embodiment, it contains 30-70 wt % hydrophilic microporous nanoparticles and 30-50 wt % polymers for polar-dominant gas absorption. In another embodiment, the composite comprises 30-70 wt % hydrophobic microporous nanoparticles and 30-50 wt % polymers for adsorbing small non-polar gases and organic compounds. A further embodiment incorporates 20-60 wt % hydrophobic mesoporous nanoparticles and 20-50 wt % polymers for adsorbing larger non-polar gases and organic compounds.
The primary objective of this invention is to develop a single, adaptable getter material capable of efficiently adsorbing a broad spectrum of gases and organic compounds, regardless of their polarity, molecular size, and surface energy characteristics.
Another objective is to provide a multi-phase nanostructured composite material as a multifunctional getter, designed to replace conventional single-phase, single-functional getters. This solution addresses the diverse outgassing challenges encountered across various microelectronic and electronic packages, vacuum systems, and analytical instruments.
This summary highlights the design principles, materials, and fabrication methods for multi-gas getters, as well as the invention's objectives. Full details are provided in the complete disclosure, accompanying figures, and claims.
The aspects of the present disclosure are best understood through the detailed description in conjunction with the accompanying figures. These descriptions and drawings are intended to be illustrative and not limiting. Although numerous specific details are provided to offer a thorough understanding of the disclosure, well-known details may be omitted to avoid obscuring the description. Additionally, various modifications to the getter design may be made without deviating from the scope of the embodiments. The invention will be further illustrated with the aid of the following figures, where:
The embodiments described in this disclosure are illustrative and not restrictive. While specific implementations are provided, alternative forms and materials may be utilized. The structural and functional details outlined here are intended to guide practitioners skilled in the art in applying and adapting the principles described. Features shown in any figure may be combined with those from other figures to create configurations not explicitly detailed. Modifications and combinations consistent with the teachings of this disclosure can be tailored to meet specific applications or requirements.
Polymer composite compositions designed for scavenging outgassed species in electronic packages take advantage of the distinct adsorptive properties of multi-phase nanomaterials. Hydrophilic microporous nanoparticles, such as zeolites, serve as molecular sieves that effectively capture small polar gases due to their structured pores and high surface energy. Hydrophobic microporous nanoparticles, such as modified zeolites, are optimized for small non-polar gases and organic compounds. Hydrophobic mesoporous nanoparticles, including modified silicas, have larger pores that enhance the adsorption of larger non-polar gases and organic compounds. These phases are bound together by a polymer matrix with low-to-medium surface energy, which not only provides mechanical support but also facilitates the physisorption of non-polar gases and organic compounds, improving the overall performance of the composite.
The multi-phase polymer composite integrates diverse nanomaterials with a broad range of surface energies-low (20-30 mJ/m2), medium (30-50 mJ/m2), and high (50-70 mJ/m2). The composite includes:
The use of multi-phase nanomaterials enables the creation of a composite getter capable of capturing a wide range of emitted gases, including organic compounds. While microporous molecular sieve materials like zeolites (e.g., 4A, 5A, or 13X) can achieve adequate adsorption capacity for certain gases, such as moisture (H2O) and smaller or weakly adsorbed organic compounds, their performance can be limited by molecular size and potential aggregation. At high concentrations, molecules may aggregate into clusters too large for small pores to accommodate. To create a getter that effectively captures a broader spectrum of gases, including larger organic compounds, mesoporous nanoparticles with pore sizes ranging from 1 nm to 50 nm are beneficial. These mesoporous materials increase the available surface area and facilitate the diffusion of larger molecules to adsorption sites, improving overall efficiency. In a hybrid multi-phase composite, mesopores handle larger gases and organic compounds, while microporous nanoparticles capture smaller molecules, providing a balanced and versatile adsorption system.
The polymer matrix functions as both a structural framework and a medium for dispersing nanoparticles, influencing porosity, adsorbent distribution, and interactions with target gases. Depending on its composition, the matrix can contribute to weak physisorption:
The composite's overall surface energy is calculated as the weighted average of the surface energy E(i) of each component and its mass fraction β(i), using the formula:
Here, n represents the number of components in the composite; for a quaternary composition, n=4. Using this method, the calculated average surface energy for the described quaternary composition falls within the range of approximately 30-50 mJ/m2, which closely matches the surface energy of outgassed gases, enabling effective adsorption across various gases and organic compounds via the different phases of the composite.
In hermetically sealed packages, non-polar gases often exhibit insufficient driving forces for adsorption due to their low partial pressures and temperature-induced desorption. Effective adsorption under such conditions requires getter materials with appropriate surface energies. As the composite's surface energy decreases, adsorption capacities improve. Zeolite-based getters, with surface energies typically ranging from 50-70 mJ/m2, are highly effective for polar molecules like water vapor but struggle to adsorb non-polar gases such as H2, N2, and O2, despite having microporous sizes of 0.3-1.0 nm. This suggests that adsorption is influenced by surface energy, material phase, and molecular pore size.
The composite's adsorption performance for hydrogen (H2) and nitrogen (N2) is minimal, primarily due to their small size, low polarizability, and weak interactions with the adsorbent materials. These gases lack dipole moments or significant polarizability, which are necessary for strong adsorption, and they are too small to effectively interact with the composite's pore structures. Materials like zeolites, modified zeolites, or modified silica are not specifically designed to adsorb small non-polar gases such as H2 and N2. While some minor adsorption may occur, the capacities for these gases are significantly lower compared to those for other gases and organic compounds. In contrast, adsorption is more pronounced for larger or more polar species, such as CO2, methane (CH4), or aromatic organic compounds, which interact more strongly with the composite.
Hydrophilic microporous nanoparticles, such as zeolites (20 wt %), primarily adsorb polar gases like H2O, CO2, ammonia (NH3), and smaller organic compounds such as methanol and ethanol. Hydrophobic microporous nanoparticles, like modified zeolites (20 wt %), excel in adsorbing aromatic hydrocarbons and non-polar organic compounds (e.g., toluene, benzene, xylene) due to their hydrophobic nature and pore structures. Hydrophobic mesoporous nanoparticles, such as modified silica (20 wt %), contribute to moisture control and provide moderate adsorption for gases such as carbon monoxide (CO), sulfur dioxide (SO2), and hydrocarbons. A polymer matrix (40 wt %), such as polyvinyl alcohol, silicone RTV, polyimide, or epoxy resin, provides structural stability and enhances gas diffusion. This composite-based getter achieves a balanced performance, making it well-suited for systems that require both moisture and organic compounds control.
Aromatic and non-polar hydrocarbons such as toluene, benzene, xylene, and hexane exhibit the highest adsorption capacities (˜6.5%) due to their affinity for hydrophobic microporous nanostructures. Hydrophobic mesoporous structures contribute moderate adsorption for polar molecules like ethylene glycol and ammonia, while also offering balanced moisture adsorption. Gases such as CO2, SO2, and methanol show moderate adsorption capacities (3.0-4.5%), benefiting from both hydrophobic micropores and mesopores. Non-polar gases and organic compounds dominate the adsorption profile, while smaller polar molecules like hydrogen (H2), ammonia (NH3), and water vapor (H2O) exhibit minimal uptake. The hydrophobic microporous phase enhances adsorption of aromatic hydrocarbons, non-polar gases (e.g., methane, ethylene), and ketones (e.g., acetone), whereas the mesoporous phase improves the adsorption of polar gases like CO2 and SO2. A 40 wt % silicone RTV polymer matrix ensures structural stability and efficient gas diffusion, making this composite getter suitable for applications requiring moderate moisture control without compromising organic compounds scavenging performance.
Polymer composite design for gas adsorption: polymer composites can be tailored as two-phase systems, combining a polymer matrix with a single type of nanoparticle for specific adsorption needs. Examples include moisture getter:
Predicting composite adsorption capacities: to estimate the gas adsorption capacity of composites, such as microporous hydrophilic 13X zeolite embedded in a silicone RTV polymer matrix, follow these steps:
This systematic approach ensures accurate predictions of composite adsorption performance.
Adsorption capacities for different zeolites:
Hierarchical porous composites for broad adsorption: Advanced composites incorporate micropores and mesopores to achieve versatile adsorption capabilities:
Challenges and enhancements in VOC adsorption: Zeolites like 4A, 5A, or 13X can adsorb gases and organic compounds effectively but face limitations with molecular aggregation or steric hindrance. These challenges include:
In the composite material, the use of larger particles (20-100 μm) can achieve an adsorption capacity of approximately 20 wt % for moisture, thanks to the intrinsic microporous structure of zeolites, which facilitates water molecule entry and adsorption within their pores. However, nanoparticles, due to their smaller size, provide a significantly higher surface area-to-volume ratio compared to micrometer-sized particles. This increased surface area allows for more accessible adsorption sites and shorter diffusion pathways for moisture molecules, potentially improving the adsorption rate. Additionally, nanoparticles often exhibit unique surface chemistry or boundary effects, such as surface defects or elevated surface energy, which can enhance adsorption under certain conditions despite having the same molecular pore size (0.3-1.0 nm).
The choice of binary, ternary, or quaternary phase getters for scavenging gases and VOCs (volatile organic compounds) from electronic packages depends on the desired composition, target molecule range, and synergistic effects among components. Binary Phase Getters: These typically combine two types of nanoparticles, such as hydrophilic microporous and hydrophobic microporous materials, or a single nanoparticle type with a polymer matrix. Hydrophilic microporous nanoparticles efficiently adsorb polar molecules like water due to their strong polar interactions, while hydrophobic microporous nanoparticles are better suited for capturing small non-polar gases or organic compounds. However, without mesoporous structures, binary getters have limited capability to adsorb larger organic compounds molecules or address both hydrophilic and hydrophobic gases simultaneously. Despite this, their straightforward design and manufacturing make binary getters a cost-effective solution for capturing a narrow range of small molecules or polar/non-polar gases.
Ternary Phase Getters: These incorporate three types of nanoparticles-hydrophilic microporous, hydrophobic microporous, and hydrophobic mesoporous-within a polymer matrix. Microporous nanoparticles are adept at capturing smaller gases and organic compounds (0.3-1 nm), including hydrophilic molecules like water and hydrophobic molecules like methane. The inclusion of mesoporous nanoparticles enhances the getter's ability to adsorb larger organic compounds (1-50 nm) that cannot penetrate micropores. This design provides a balance between complexity and performance, making ternary getters ideal for applications requiring the management of both small and large emissions across a diverse range of gases and VOCs.
Quaternary Phase Getters: These combine hydrophilic microporous, hydrophobic microporous, and hydrophobic mesoporous nanoparticles with an additional functional phase, such as catalytic nanoparticles or other materials, embedded in a polymer matrix. This configuration enhances adsorption kinetics and introduces capabilities like catalytic breakdown of organic compounds. The fourth phase also improves stability and nanoparticle dispersion through surface modifiers or binding agents, optimizing gas and organic compounds adsorption across a broad spectrum of sizes and polarities. Quaternary getters are particularly suited for environments with complex gas emissions, such as advanced electronic packages. While their manufacturing process is more intricate than that of binary or ternary getters, quaternary getters offer unparalleled reliability and efficiency, making them ideal for mission-critical applications with a 20-year operational lifespan.
The layers in the getter assembly 80 offer complementary functions, with the top layer designed to capture larger molecules and inner layers focusing on smaller or more polar molecules. This sequential layering creates a high surface-area-to-volume ratio by dispersing nanoparticles layer by layer. Molecules passing through one layer are captured by subsequent layers, utilizing the full getter thickness for improved adsorption efficiency. The multilayer design also minimizes thermal expansion mismatch stresses, reducing risks of delamination or mechanical failure. Each layer stabilizes the overall structure under thermal or chemical stress, maintaining performance even if one layer becomes saturated or damaged. This approach prevents nanoparticle clustering, ensuring uniform dispersion and eliminating voids or defects that could lower adsorption efficiency. Thin, repeated coatings enhance layer adhesion and robustness, allowing precise control over thickness and performance. Layer composition can also be tailored to prioritize specific gases or operate in extreme conditions, meeting application-specific requirements.
The binary-phase composite in
In another configuration the getter assembly 90 functions as a high-capacity dual-purpose moisture and hydrogen getter. Here, the first layer is 3A zeolite, the second layer consists of hydrophilic silicas, and the substrate is titanium foil. This design offers superior capacity compared to conventional getters with 3A zeolite or PdO-doped particles. The hydrophilic silica layer provides exceptional surface area for moisture adsorption, while the titanium substrate effectively absorbs hydrogen through hydride formation. The 3A zeolite/polymer top layer acts as a selective barrier, allowing only small molecules like moisture (H2O) and hydrogen (H2) to pass through while blocking larger contaminants. This selective filtration reduces fouling and extends the getter's service life. Titanium, a highly efficient hydrogen absorber, forms stable hydrides for durable and long-term hydrogen scavenging, performing effectively at low to moderate temperatures typical of electronic packages. Unlike PdO-based systems that degrade over time, titanium hydrides ensure a stable and reliable hydrogen absorption mechanism, making this assembly ideal for demanding applications.
In a specialized configuration, the getter assembly 90 in
To fabricate a quaternary or ternary composite film with hydrophilic microporous, hydrophobic microporous, and hydrophobic mesoporous nanoparticles embedded in a polymer matrix and applied onto a substrate, the following steps are employed:
The curing and post-fabrication treatment processes include:
