Getter composition and dispensable paste comprising said getter composition - Patents.com

Abstract

A getter composition for use in controlling the amount of moisture and organic gases in a sealed electronic or optoelectronic device, comprising a blend of a first getter and a second getter powder in a mass ratio comprised between 0.1 and 5.0, the first getter being polyphenylene oxide (PPO) or poly(2,6-diphenyl-p-phenylene oxide) (PPPO) and the second getter being faujasite (FAU) zeolite or a mixture of faujasite (FAU) zeolite and Linde type A (LTA) zeolite in a ratio comprised between 0.1 and 5.0. The present invention also relates to a dispensable paste comprising a resin and the getter composition.

Description

[Technical field]

[0001] The present invention relates to dispersible getter compositions to be used to control the amount of moisture and organic gases in hermetically sealed electronic or optoelectronic devices, and to dispensable pastes comprising said getter compositions. [Background technology]

[0002] It is commonly known that electronic devices, and particularly some of their components, are sensitive and exhibit reduced performance when exposed to undesirable contaminants, including moisture and other contaminant gases, such as oxygen, hydrogen, and volatile organic compounds (VOCs).

[0003] In the current state of the art, the primary techniques for protecting organic electronic devices (i.e., electronic devices having organic components) from degradation include applying a barrier coat or sealant along the boundaries of the organic electronic device to prevent ingress of contaminants into its interior, combined with placing an absorbent or adsorbent getter material within the sealed device to remove contaminants into its internal sealed volume.

[0004] The primary desiccants used to remove water typically include metal oxides (such as CaO, BaO, MgO, etc.); metal hydrides; metal salts; powdered zeolites (such as 4A and 3A molecular sieves); metal perchlorates; superabsorbent polymers, and metals that react with water, such as calcium.

[0005] For example, EP1874885 discloses adhesives or sealants filled with radiation curable desiccant disposed around the periphery of electronic and optoelectronic devices, the desiccant filler being used as a moisture sweep or barrier feature. Similarly, WO2013165637 provides radiation or heat curable encapsulants suitable for sealing and adhering substrates and covers for organic electronic devices that protect the active organic components of the device from moisture and oxygen using one of the desiccant fillers reported above.

[0006] US20060283546 relates to a method for encapsulating and thus sealing electronic devices, comprising a hybrid getter material prepared from a zeolite getter powder combined with a polyimide resin.

[0007] In addition to the purpose of moisture barrier, some application examples report solutions aimed at ensuring the absorption of volatile organic chemical compounds (VOCs), such as WO2008033647 and WO2010093237, which disclose optoelectronic devices with an electrically insulating material that is impermeable to VOCs selected from among substituted or unsubstituted carbon compounds, including alkanes, cycloalkanes, aromatics, alcohols, ethers, esters, ketones, halocarbons, amines, organic acids, cyanates, nitrates, and nitriles. In both cases, the drying effect is achieved by using various sorbent media, such as activated carbon, alumina, and other metal oxides, zeolites, organic sorbents including hypercrosslinked systems. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] EP1874885 [Patent Document 2] WO2013165637 [Patent Document 3] US20060283546 [Patent Document 4] WO2008033647 [Patent Document 5] WO2010093237 [Non-patent literature]

[0009] [Non-Patent Document 1] "Monolithic Aerogels Based on Poly(2,6-diphenyl-1,4-phenylene oxide) and Syndiotactic Polystyrene", ACS Appl. Mater. Interfaces 2013, 5, 12, 5493~5499 Summary of the Invention [Problem to be solved by the invention]

[0010] One of the main objectives in this field is to effectively reduce and control the amount of water and organic gases simultaneously, but the drawback is that most of the typical getters and fillers used can reduce their effectiveness with respect to some chemical species when in competition with others. [Means for solving the problem]

[0011] The present inventors have unexpectedly discovered that Faujasite (FAU) zeolite, or a mixture of FAU and Linde Type A (LTA) zeolites, when combined with polyphenylene oxide (PPO) or poly(2,6-diphenyl-p-phenylene oxide) (PPPO) species in specific ratios, significantly reduces the negative impact of VOCs on zeolite water absorption, with the water absorption capacity remaining substantially unchanged (i.e., within the error of measurement) despite the presence of the VOC species. At the same time, the negative impact of water on VOC adsorption capacity has not been reported, and the compositions disclosed herein do not exhibit reduced VOC adsorption despite the presence of water.

[0012] The object of the present invention is therefore a dispersible getter composition comprising a blend of a first getter and a second getter, the first getter being a PPO or PPPO and the second getter being a Faujasite (FAU) zeolite or a mixture of FAU and Linde type A (LTA) zeolite. In particular, said composition is characterized in that the ratio between the first getter and the second getter is comprised between 0.1 and 5.0, preferably between 0.1 and 2.5. Compositions characterized by higher ratios do not result in significant water adsorption that becomes undetectable by conventional measurement techniques.

[0013] Further, the getter composition comprises X comprising between 1.0 and 50.0 μm (calculated from the volume distribution). 90 In a further preferred embodiment, the particle size distribution is in the form of a powder having a controlled particle size distribution characterized by a X value comprised between 1.0 and 20.0 μm. 90 It is characterized by its value.

[0014] A further advantage related to the invention is linked to the possibility of introducing said composition into a device and, as a result, removing from the interior of the device both moisture and organic compounds that may be present as residues of the manufacturing process or that may be generated during the operation of the device. In that connection, in order to improve the possibility of introducing a getter into the device, said composition should be dispersed in a matrix, i.e. may be combined with a resin to prepare a dispensable paste.

[0015] In particular, the getter blend of the present invention disclosed can be dispersed in an epoxy or phenolic resin or a mixture thereof and used in a dispensable paste in an amount constituting between 10% and 50% by weight relative to the total amount of the paste including the hardener for the resin. To have a dispensable paste, the composition is characterized by a ratio between the first and second getters constituting between 0.1 and 5.0, preferably between 0.1 and 2.5.

[0016] Since one of the goals in VOC adsorption is to have a solvent-free formulation, the resin is essentially based on an epoxy resin selected from bisphenol F or bisphenol A, or a phenolic resin such as poly[(phenyl glycidyl ether)-co-formaldehyde], or a mixture thereof, in an amount constituting between 50% and 90% by weight of the total amount of resin (including hardener).

[0017] To improve the viscosity of the paste, and therefore its dispensability, the FAU zeolite can be mixed with Linde Type A (LTA) zeolite, with the ratio between FAU and LTA zeolite constituting between 0.1 m and 5.0.

[0018] Further additional compounds, such as colorant molecules selected from among rare earth pigments and organic heterocyclic compounds, may be added to the paste in an amount constituting between 0.1% and 10% by weight of the total amount of the paste, in order to improve the visibility of the paste when applied to a surface.

[0019] Dispensable pastes according to the present invention are suitable for dispensing through methods commonly used in manufacturing and laboratory processes, such as pneumatic syringe dispensing systems.

[0020] A further object of the invention is also a component for an electronic device, comprising at least one surface onto which the paste is distributed.

[0021] In a preferred embodiment, said component of an electronic device having a surface at least partially covered with a paste according to the invention is a cover lid for an airtight package of an electronic device.

[0022] The present invention will now be described in more detail with reference to the following non-limiting examples. Modifications or variations of the embodiments embodied herein that are obvious to those skilled in the art are encompassed by the appended claims. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[0023] Getter powder blends for samples S1-S3 and comparative examples C1-C4 reported in Table 1 are prepared by manually mixing pure getter powders. The adsorption capacity is measured (HO and VOC depletion) using a state-of-the-art system, mass spectrometry.

[0024] To produce dispensable pastes for Samples S4-S10 and Comparative Examples C5-C8 shown in Table 2, the resin plus hardener (45-65% by weight) and getter powder blend (35-55% by weight) are mixed manually in 10 g batches in the amounts specified in the table and then refined with a suitable device, for example a laboratory three-roll mill, for 5 minutes.

[0025] Both the sample and the comparative example were prepared by using polyphenylene oxide (PPO) as the first getter, since it is generally known to behave similarly to poly(2,6-diphenyl-p-phenylene oxide) (PPPO) (see, for example, "Monolithic Aerogels Based on Poly(2,6-diphenyl-1,4-phenylene oxide) and Syndiotactic Polystyrene", ACS Appl. Mater. Interfaces 2013, 5, 12, 5493-5499).

[0026] The particle size distribution of the dry powder is measured with a laser diffraction instrument. Dispensability testing is performed using a pneumatic dispensing system connected to a standard pneumatic line equipped with a cylindrical needle with a diameter of 300 to 800 μm.

[0027] Dispensability is visually confirmed and labeled / marked as follows: "BEST": Flow from the syringe is continuous and paste deposition is uniform. "OK" if maximum pressure (5-6 bar) from the standard air pressure line is required. · "BAD" - The paste is too viscous and therefore not homogenous after refining: it cannot be distributed.

[0028] [Table 1] 10

[0029] [Table 2]

[0030] The reported results clearly show the technical effect of the present invention; in fact, as reported in comparative example C3, it is possible to confirm the negative impact of VOCs on the FAU zeolite water adsorption capacity, which drops by 10% when the getter composition is exposed to both toluene and water. In contrast, when samples S1 to S3 prepared according to the present invention were tested, despite the presence of VOCs, the relative water adsorption did not change significantly with respect to the predicted capacity calculated based on the amounts of the various species (PPO, FAU, and LTA) and their relative specific capacity, with the maximum change being about 2.8% for S3.

[0031] As confirmed by the results reported in Table 1, good adsorption capacities can be obtained when simple FAU zeolite is tested as a getter, however, it is well known that simple zeolites are not suitable for dispersion in sufficient quantities to be effective in the application in question. As shown in samples S2 and S3, it is possible to add a second zeolite (LTA) while maintaining a good effect on water adsorption; in contrast, as reported in comparative example C4, when only LTA zeolite is used in combination with PPO, the toluene adsorption capacity is reduced relative to the value that can be obtained when FAU zeolite is used as the second getter.

[0032] In table 2 it is possible to see the quality assessment of pastes S4 to S10 comprising getter compositions prepared according to the invention, and in particular S4, which is a paste comprising composition S3. The reported results also demonstrate the possibility of using both S4 to S8 samples prepared by using different resins, indeed bisphenol F resin, and S9 to S10, respectively, prepared with bisphenol A and poly[(phenyl glycidyl ether)-co-formaldehyde] resins, demonstrating good dispensability. Considering at the same time the comparative examples, it is clear that it is not possible to obtain a dispensable paste when the amount of filler is higher than 50% (C5) or when the ratio between FAU and LTA zeolite is too high, suggestively higher than 5.0 (C6), or when the second zeolite LTA is not present in the composition (C7), or when the ratio between the first and second getter is higher than 5.0 (C8).

Claims

1. 1. A dispersible getter composition comprising a blend of powders of a first getter and a second getter, the first getter is polyphenylene oxide (PPO) or poly(2,6-diphenyl-p-phenylene oxide) (PPPO); the second getter is a faujasite (FAU) zeolite or a mixture of faujasite (FAU) zeolite and Linde type A (LTA) zeolite in a weight ratio of between 0.1 and 5.0; The mass ratio between the first getter and the second getter is comprised between 0.1 and 5.0; and The getter powder has an X diameter of between 1.0 and 50.0 μm. 90 2. A getter composition characterized by a particle size distribution having a value.

2. The getter powder is 90 10. The getter composition of claim 1, characterized by a particle size distribution comprised between 1.0 and 20.0 μm.

3. 10. A dispensable paste comprising an epoxy or phenolic resin or a mixture thereof and the getter composition of claim 1, wherein the resin, including a hardener, constitutes between 50% and 90% by weight of the total paste volume, and the getter composition constitutes between 10% and 50% by weight of the total paste volume.

4. 4. The dispensable paste of claim 3, wherein the additional colorant compound is added in an amount comprising between 0.1% and 10% by weight relative to the total amount of the paste.

5. 5. The dispensable paste of claim 4, wherein the colorant compound is a rare earth pigment or an organic heterocyclic compound.

6. 4. The dispensable paste of claim 3, wherein the epoxy resin is selected from bisphenol F or bisphenol A resin, and the phenolic resin is poly[(phenyl glycidyl ether)-co-formaldehyde] resin.

7. 4. The dispensable paste of claim 3, wherein the mass ratio between the first getter and the second getter is comprised between 0.1 and 2.

5.

8. 8. A component for an electronic device comprising at least one surface onto which a paste according to any one of claims 3 to 7 has been distributed.

9. 10. The component of claim 8, which is a cover lid for an airtight package of the electronic device.