Getter composition and dispensable paste comprising said getter composition

Abstract

Getter composition to be used for controlling the amount of moisture and organic gases in sealed electronic or optoelectronic devices, said composition comprising a blend of first getter and second getter powders in a weight ratio comprised between 0.1 and 5.0, wherein the first getter is polyphenylene oxide (PPO) or Poly(2,6-diphenyl-p-phenylene oxide) (PPPO) and the second getter is a Faujasite (FAU) zeolite or a mixture of a Faujasite (FAU) zeolite and a Linde Type A (LTA) zeolite with a ratio comprised between 0.1 and 5.0. The invention also relates to a dispensable paste comprising a resin and the getter composition.

Claims

1. A dispensable paste, comprising: an epoxy resin; and a getter composition comprising a blend of a first getter powder and a second getter powder, wherein: the first getter powder is polyphenylene oxide (PPO) or poly(2,6-diphenyl-p-phenylene oxide) (PPPO); the second getter powder is a Faujasite (FAU) zeolite or a mixture of a Faujasite (FAU) zeolite and a Linde Type A (LTA) zeolite having a weight ratio FAU to LTA of 0.1 to 5.0; a weight ratio of the first getter powder to the second getter powder is 0.1 to 5.0; and the getter powders have a particle size distribution X.sub.90 of 1.0 to 50.0 ?m; and wherein: the resin, including any curing agent, is present in an amount of 50 to 90 wt % based on a total weight of the paste; and the getter composition is present in an amount of 10 to 50 wt % based on the total weight of the paste.

2. The dispensable paste according to claim 1, further comprising one or more colorant compounds in an amount 0.1 to 10 wt % based on the total weight of the paste.

3. The dispensable paste according to claim 2, wherein the one or more colorant compounds comprise at least one selected from the group consisting of a rare earth pigment and an organic heterocyclic compound.

4. The dispensable paste according to claim 3, wherein: the epoxy resin comprises at least one selected from the group consisting of a bisphenol F epoxy resin, a bisphenol A epoxy resin, and a poly[(phenyl glycidyl ether)-co-formaldehyde] resin.

5. The dispensable paste according to claim 3, wherein the weight ratio of the first getter powder to the second getter powder is 0.1 to 2.5.

6. The dispensable paste according to claim 2, wherein: the epoxy resin comprises at least one selected from the group consisting of a bisphenol F epoxy resin, a bisphenol A epoxy resin, and a poly[(phenyl glycidyl ether)-co-formaldehyde] resin.

7. The dispensable paste according to claim 2, wherein the weight ratio of the first getter powder to the second getter powder is 0.1 to 2.5.

8. The dispensable paste according to claim 1, wherein: the epoxy resin comprises at least one selected from the group consisting of a bisphenol F epoxy resin, a bisphenol A epoxy resin, and a poly[(phenyl glycidyl ether)-co-formaldehyde] resin.

9. The dispensable paste according to claim 8, wherein the weight ratio of the first getter powder to the second getter powder is 0.1 to 2.5.

10. The dispensable paste according to claim 1, wherein the weight ratio of the first getter powder to the second getter powder is 0.1 to 2.5.

11. The dispensable paste according to claim 1, wherein the getter powders have a particle size distribution X.sub.90 of 1.0 to 20.0 ?m.

12. The dispensable paste according to claim 1, wherein the first getter powder is polyphenylene oxide (PPO) and the second getter powder is a mixture of Faujasite (FAU) zeolite and Linde Type A (LTA) zeolite having a weight ratio FAU to LTA of 0.1 to 5.0.

13. A component for an electronic device, comprising at least one surface on to which the paste according to claim 1 has been dispensed.

14. The component according to claim 13, wherein the component is a cover lid for hermetic packaging of the electronic device.

Description

EXAMPLES

(1) The getter powders blends of samples S1-S3 and comparative examples C1-C4 reported in Table 1 are prepared by mixing manually the pure getter powders. The adsorption capacity is measured using state-of-the-art systems, mass spectrometer (H.sub.2O and VOCs depletion).

(2) To produce the dispensable paste of samples S4-S10 and comparative examples C5-C8 shown in Table 2, the resin plus the curing agent (45-65% wt) and the getter powders blends (35-55 wt %) are manually mixed in the amounts specified in the table in 10 g batches and then refined with appropriate devices, e.g. using a laboratory three-roll mill for 5 minutes.

(3) Both the samples and the comparative examples where prepared by using polyphenylene oxide (PPO) as first getter since it is commonly know the equivalent behavior with respect 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).

(4) The particle size distribution of the dry powders is measured with a laser diffraction instrument. The dispensability test is performed using a pneumatic dispensing system connected to a standard pneumatic line, with cylindrical needles from 300 to 800 ?m diameter.

(5) The dispensability is visually confirmed and labelled/marked as: BEST if the flow from the syringe is continuous and the paste deposit is uniform. OK if the maximum pressure (5-6 bar) from a standard pneumatic line is needed. BAD if the paste is too viscous and so it is not uniform after refining: it cannot be dispensed.

(6) TABLE-US-00001 TABLE 1 Expected H.sub.2O capacity Toluene capacity PPO FAU LTA H.sub.2O capacity (in H.sub.2O + toluene) Expected toluene (in H.sub.2O + toluene) Ref. (wt %) (wt %) (wt %) (% wt) (% wt) capacity (% wt) (% wt) C1 0 0 100 23.1 23.1 undetectable undetectable C2 100 0 0 undetectable undetectable 14.9 13.8 C3 0 100 0 27.3 24.6 21.9 23.0 C4 67 0 33 7.6 8.4 10.0 10.5 S1 50 50 0 13.6 13.9 18.4 15.3 S2 50 25 25 12.6 12.5 12.9 11.8 S3 15 45 40 21.5 20.9 12.1 12.3

(7) TABLE-US-00002 TABLE 2 Total PPO FAU LTA filler Dispensability Ref. (% wt) (% wt) (% wt) (% wt) FAU/LTA results S4 6 18 16 40 1.1 BEST S5 8 20 18 46 1.1 OK S6 6 3 26 35 0.1 BEST S7 7 31 7 45 4.4 OK S8 25 5 5 35 1.0 OK S9 5 16 14 35 1.1 BEST S10 5 16 14 35 1.1 BEST C5 10 23 22 55 1.0 BAD C6 7 34 4 45 8.5 BAD C7 0 50 0 50 BAD C8 39 4 3 46 1.3 BAD

(8) The reported results clearly show the technical effect of the invention; indeed, as reported in comparative example C3, it is possible to confirm the negative effect of VOCs on the FAU zeolite water adsorption capacity, which decreases by 10% when the getter composition is exposed to both toluene and water. On the contrary, when samples S1-S3 prepared according to the present invention are tested, despite the VOC presence, the relative water adsorption does not significantly change with respect to the expected capacity calculated on the base of the amount of the different species (PPO, FAU and LTA) and their relative intrinsic capacity, the largest change being about 2.8% for S3.

(9) As confirmed by the results reported in Table 1, it is well known that good adsorption capacity may be obtained when the simple FAU zeolite is tested as getter, however the simple zeolites are not suitable to be dispersed in sufficient amount to be effective in the applications of interest. As shown in samples S2 and S3, it is possible to add a second zeolite (LTA) while maintaining the positive effect on the water adsorption; in contrast, as reported in comparative example C4, when only the LTA zeolite is employed combined with PPO, the toluene adsorption capacity decreases with respect to the value which can be obtained when the FAU zeolite is employed as second getter.

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