Patent EP0170468A1 successfully refreshed from Google Patents.
EP0170468A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Resistor compositions, methods of making them and articles comprising them
Assignee: Electro Materials Corp of America
•
Filing: 1985-07-17
•
Granted: —
•
Expires: 2005-07-17
Abstract
Abstract This invention is concerned with resistor compositions, methods of making them and articles comprising them. The resistor compositions comprise solid long chain phenolic resin, liquid short chain phenolic resin and, dispersed therein, a mixture comprising carbon black and graphite particles. The resistor compositions are capable of withstanding high humidity conditions without significant changes in resistivity and are capable of low ohmic values without the need to use metals.
Inventors
- 👤 Frank Wayne Martin
- 👤 Samson Shahbazi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 20:48
CPC Classifications
C; C08; C08L; C08L61/00; C08L61/04; C08L61/06; H; H01; H01C; H01C7/00; H01C7/003; H01C7/005; C08K; C08K3/00; C08K3/02; C08K3/04; H01C17/00; H01C17/06; H01C17/065; H01C17/06506; H01C17/06513; H01C17/0652; H01C17/06573; H01C17/06586
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
64 words
A resistor composition capable of withstanding high humidity conditions comprising: (A) a one-step heat-reactive resin system comprising liquid phenolic resin having a number average molecular weight of from 300 to 400, and solid phenolic resin having a number average molecular weight of from 400 to 500; and (B) a mixture of carbon black and graphite particles, said mixture being dispersed in said resin system.
Claim 2
Dependent Claim
64 words
A resistor composition capable of withstanding high humidity conditions comprising: (A) a one-step heat-reactive resin system comprising liquid phenolic resin having a number average molecular weight of from 300 to 400, and solid phenolic resin having a number average molecular weight of from 400 to 500; and (B) a mixture of carbon black and graphite particles, said mixture being dispersed in said resin system.
Claim 3
Dependent Claim
54 words
A composition as claimed in claim 1, wherein: (a) the weight ratio of (A) to (B) is from 85:15 to 50:50; and/or (b) the weight ratio of carbon black to graphite is from 10:90 to 50:50; and/or (c) the weight ratio of liquid phenolic resin to solid phenolic resin is from 1:1 to 100:1.
Claim 4
Dependent Claim
43 words
A composition as claimed in claim 1 or claim 2, wherein the average particle size of the carbon black particles is from 10 millimicrometres to 100 millimicrometres, and/or the average particle size of the graphite particles is from 1 micrometre to 10 micrometres.
Claim 5
Dependent Claim
27 words
A composition as claimed in claim 1 or claim 2, wherein the average particle size of the carbon black-graphite mixture is from 1 micrometre to 10 micrometres.
Claim 6
Dependent Claim
48 words
A composition as claimed in any of claims 1 to 4, wherein the surface area of the carbon black is from 500 m 2 /g to 1 50 0 m2/g, and/or the surface area of the graphite is from 1 m 2 /g to 2 m 2 /g.
Claim 7
Dependent Claim
29 words
A composition as claimed in any of claims 1 to 5, wherein the weight ratio of the surface area of carbon black to graphite is from 500:1 to 1500:1.
Claim 8
Dependent Claim
23 words
A composition as claimed in any of claims 1 to 6 having a fineness of grind of from 1 micrometre to 7 micrometres.
Claim 9
Dependent Claim
25 words
A composition as claimed in any of claims 1 to 7 having an ohmic value of from 708.7 to 5905.5 ohms/sq/mm (18 to 150 ohms/sq/mil).
Claim 10
Dependent Claim
24 words
A composition as claimed in any of claims 1 to 8 having an ohmic value which varies less than ±1.0% at 85% relative humidity.
Claim 11
Dependent Claim
31 words
A composition as claimed in any of claims 1 to 8 having a resistance value which varies less than ±1.0% when the relative humidity varies from 80% to 90% at 85°C.
Claim 12
Independent Claim
110 words
A method of forming, on a substrate, a resistor composition as claimed in any of claims 1 to 10 comprising: (i) dissolving solid phenolic resin having a number average molecular weight of from 400 to 500 in solvent to form a solution; (ii) mixing said solution with liquid phenolic resin having a number average molecular weight of from 300 to 400; (iii) dispersing a mixture of carbon black and graphite particles in the solution to form a mixture; (iv) applying the mixture to a substrate, by silk screening; and (v) curing the mixture, e.g. at a temperature of from about 150°C to 165°C from about 60 to about 120 minutes.
Claim 13
Dependent Claim
33 words
An article comprising a substrate, e.g. a printed circuit board, at least a portion of the surface of which is coated with a composition as claimed in any of claims 1 to 10.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.