US4720431A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silicone encapsulated devices
Assignee: AMERICAN TELEPHONE AND TELEGRAPH Co AT&T TECHNOLOGIES Inc
•
Filing: 1986-05-21
•
Granted: 1988-01-19
•
Expires: 2006-05-21
Abstract
Abstract The addition of a low viscosity (2 to 100 centipoise) polysiloxane such asolydimethylsiloxane to a two-part heat curable polysiloxane system substantially eliminates the formation of bubbles when such system is employed as a potting compound for encapsulating devices such as electronic devices.
Inventors
- 👤 Ching-Ping Wong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:54
CPC Classifications
H; H10; H10W; H10W74/00; H10W74/40; H10W74/47; H10W74/476; C; C08; C08L; C08L83/00; C08L83/04; C08G; C08G77/00; C08G77/04; C08G77/12; C08G77/20; Y; Y10; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31652; Y10T428/31663
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
216 words
An article of manufacture comprising an electronic device having an essentially bubble-free, cured, cast silicone resin potting compound encapsulating said device, wherein said potting compound is formed by heat-curing a two-part mixture comprising relatively high viscosity polysiloxane, at least one part of which contains a platinum catalyst in an amount sufficient to catalyze a cross-linking reaction upon mixing said two parts with the application of heat, and at least one part of which further contains 5 to 15 weight percent of a low viscosity polysiloxane having a similar reactive group as the high viscosity polysiloxane in said part, said low viscosity polysiloxane having a viscosity at 25° C. of from 2 to 100 centipoise, and wherein the high viscosity polysiloxane of one part consists essentially of a polysiloxane of one part consists essentially of a polysiloxane having reactive ##STR3## groups wherein n is an integer such that the viscosity at 25° C. is from 750 to 1250 centipoise and wherein the high viscosity polysiloxane of the other part consists essentially of a polysiloxane having reactive ##STR4## groups where m is an integer such that the viscosity at 25° C. is from 2500 to 3500 centipoise and wherein R 1 -R 6 are selected from the group consisting of low molecular weight alkyl groups and aryl groups.
Claim 2
Dependent Claim
216 words
An article of manufacture comprising an electronic device having an essentially bubble-free, cured, cast silicone resin potting compound encapsulating said device, wherein said potting compound is formed by heat-curing a two-part mixture comprising relatively high viscosity polysiloxane, at least one part of which contains a platinum catalyst in an amount sufficient to catalyze a cross-linking reaction upon mixing said two parts with the application of heat, and at least one part of which further contains 5 to 15 weight percent of a low viscosity polysiloxane having a similar reactive group as the high viscosity polysiloxane in said part, said low viscosity polysiloxane having a viscosity at 25° C. of from 2 to 100 centipoise, and wherein the high viscosity polysiloxane of one part consists essentially of a polysiloxane of one part consists essentially of a polysiloxane having reactive ##STR3## groups wherein n is an integer such that the viscosity at 25° C. is from 750 to 1250 centipoise and wherein the high viscosity polysiloxane of the other part consists essentially of a polysiloxane having reactive ##STR4## groups where m is an integer such that the viscosity at 25° C. is from 2500 to 3500 centipoise and wherein R 1 -R 6 are selected from the group consisting of low molecular weight alkyl groups and aryl groups.
Claim 3
Dependent Claim
21 words
The article of manufacture recited in claim 1 wherein said polysiloxanes are selected from the group consisting of polydialkylsiloxanes and polyalkylarlysiloxanes.
Claim 4
Dependent Claim
17 words
The article of manufacture recited in claim 1 wherein said polysiloxanes are selected from polydimethylsiloxane and polymethylphenylsiloxanes.
Claim 5
Dependent Claim
43 words
The article of manufacture recited in claim 3 wherein the low viscosity polysiloxane has a viscosity of from 20 to 30 centipoise and is present in an amount equal to 5 to 10 weight percent of the part to which it is added.
Claim 6
Dependent Claim
30 words
The article of manufacture recited in claim 4 further comprising in the silicone resin potting compound at least one member of the group selected from silica, alumina and carbon black.
Claim 7
Dependent Claim
27 words
The article of manufacture recited in claim 1 wherein the first part and second part are mixed in a weight ratio of from between 1:1 to 2:1.
Claim 8
Dependent Claim
56 words
The article of manufacture recited in claim 6 wherein the low viscosity polysiloxane is a polydimethylsiloxane which is added to either the two parts and has a viscosity of from 20 to 30 centipoise and is present in an amount equal to from 5 to 10 weight percent of the part to which it is added.
Claim 9
Dependent Claim
38 words
The article of manufacture recited in claim 6 wherein the silicone resin potting compound further comprises up to 45 weight percent of a filler selected from silica and alumina and up to one weight percent of carbon black.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-01-18 | 1991-07-20 | 1992-01-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-18 | 1995-07-20 | 1996-01-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-18 | 1999-07-20 | 2000-01-19 | $7700.00 | Window Closed / Lapsed |