US5114447A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ultra-high efficiency porous metal filter
Assignee: Mott Corp
•
Filing: 1991-03-12
•
Granted: 1992-05-19
•
Expires: 2011-03-12
Abstract
Abstract An ultra-high efficiency particulate air filter for use in the microelectronics manufacturing industry is formed as a fully homogeneous sintered metal filter that exhibits an efficiency substantially in excess of a 6 log reduction and preferably equal to or exceeding a 9 log reduction (an efficiency of 99.9999999%). The filter can be used as a process gas in-line filter in state of the art gas supply systems. The porous metal filter exhibits long term stability relative to mechanical or thermal stress and operates within the desired ultra-high efficiency levels even under high pressure conditions. It does not exhibit an outgassing problem and there is no particle shedding. These features are provided within a unit no larger than those conventionally employed heretofore with organic membranes and under substantially identical operating conditions.
Inventors
- 👤 Christopher B. Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 01:46
CPC Classifications
B; B01; B01D; B01D39/00; B01D46/00; B01D46/0002; B01D46/0012; B01D39/14; B01D39/20; B01D39/2027; B01D39/2031; B01D39/2034; B01D46/10; B01D46/12; B22; B22F; B22F3/00; B22F3/10; B22F3/11; B22F3/1103
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
89 words
An ultra-high efficiency particulate air filter for use in filtering process gases for the semiconductor and microelectronics manufacturing industries comprising a filter element made from porous sintered metal, said element having a filtration efficiency relative to its most penetrating particle size of at least 6 log reduction and a specific surface per unit area of at least 0.055 m 2 /cm 2 when standardized to a thickness of 0.068 inch, said filtration efficiency being measured at a flow rate of 30 SLPM for an 11.3 in. 2 filter area.
Claim 2
Dependent Claim
89 words
An ultra-high efficiency particulate air filter for use in filtering process gases for the semiconductor and microelectronics manufacturing industries comprising a filter element made from porous sintered metal, said element having a filtration efficiency relative to its most penetrating particle size of at least 6 log reduction and a specific surface per unit area of at least 0.055 m 2 /cm 2 when standardized to a thickness of 0.068 inch, said filtration efficiency being measured at a flow rate of 30 SLPM for an 11.3 in. 2 filter area.
Claim 3
Dependent Claim
28 words
The particulate air filter of claim 1 wherein said sintered metal element is formed from metal powder having a presintered mean particle size of less than 20 microns.
Claim 4
Dependent Claim
17 words
The particulate air filter of claim 2 wherein the mean particle size is less than 10 microns.
Claim 5
Dependent Claim
31 words
The particulate air filter of claim 1 wherein the sintered element has a density of at least 5 g/cc and an isopropyl alcohol bubble point of at least 8 inches Hg.
Claim 6
Dependent Claim
27 words
The particulate air filter of claim 1 wherein the sintered metal element has undergone a degree of sintering sufficient to hold all powder particles therein during use.
Claim 7
Dependent Claim
23 words
The particulate air filter of claim 1 wherein the sintered metal element has undergone a degree of sintering sufficient to withstand sinter-neck reduction.
Claim 8
Dependent Claim
27 words
The particulate air filter of claim 1 having a pressure drop of less than 15 psid at a rated flow of 30 SLPM existing at atmospheric pressure.
Claim 9
Dependent Claim
23 words
The particulate air filter of claim 1 wherein the metal is selected from the group consisting of stainless steel, nickel and nickel alloys.
Claim 10
Dependent Claim
42 words
The particulate air filter of claim 1 wherein the filter element comprises a plurality of filter members stacked therein in such a manner as to provide a porous surface area at least about seven times the volume occupied by the filter element.
Claim 11
Dependent Claim
20 words
The particulate air filter of claim 1 wherein the element has an efficiency of at least a 9 log reduction.
Claim 12
Dependent Claim
64 words
An ultra-high efficiency particulate air filter comprising a filter element of porous sintered metal powder having a presintered mean particle size substantially less than 20 microns and a sintered density of at least 5 g/cc., the filter element having been sintered to a degree sufficient to hold the metal powder permanently in position and less than would cause reduction in filtration efficiency below 99.9999%.
Claim 13
Dependent Claim
64 words
An ultra-high efficiency particulate air filter comprising a filter element of porous sintered metal powder having a presintered mean particle size substantially less than 20 microns and a sintered density of at least 5 g/cc., the filter element having been sintered to a degree sufficient to hold the metal powder permanently in position and less than would cause reduction in filtration efficiency below 99.9999%.
Claim 14
Dependent Claim
26 words
The filter of claim 11 having a filtration efficiency that is at least a 6 log reduction when measured at a flow rate of 30 SLPM.
Claim 15
Dependent Claim
15 words
The filter of claim 12 wherein the efficiency is at last a 9 log reduction.
Claim 16
Dependent Claim
32 words
The filter of claim 11 wherein the filter element has a specific surface per unit area of at least 0.55 m 2 /cm 2 when standardized to a thickness of 0.068 inch.
Claim 17
Dependent Claim
25 words
The filter of claim 11 having a pressure drop of less than 15 psid at a rated flow of 30 SLPM exiting at atmospheric pressure.
Claim 18
Dependent Claim
14 words
The filter of claim 11 wherein the particle size is less than 10 microns.
Claim 19
Dependent Claim
24 words
The particulate air filter of claim 11 wherein the metal powder is selected from the group consisting of stainless steel, nickel and nickel alloys.
Claim 20
Dependent Claim
42 words
The particulate air filter of claim 11 wherein the filter element comprises a plurality of filter members stacked therein in such a manner as to provide a porous surface are at least about seven times the volume occupied by the filter element.
References Cited (Backward Citations)
FR873926A
Cited
US2430078A
Cited
US2826805A
Cited
US2997777A
Cited
US3581902A
Cited
US3557536A
Cited
US3853504A
Cited
US3950152A
Cited
DE3413213A1
Cited
US4686041A
Cited
SU1242214A1
Cited
US4637877A
Cited
US4687579A
Cited
US4793922A
Cited
US4758272A
Cited
US4902314A
Cited
US4902319A
Cited
US4886533A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-05-19 | 1995-11-18 | 1996-05-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-05-19 | 1999-11-18 | 2000-05-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-05-19 | 2003-11-18 | 2004-05-19 | $7700.00 | Window Closed / Lapsed |