US5670250A
Expired / Lapsed
US
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Circuit board prepreg with reduced dielectric constant
Assignee: Isola USA Corp
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Filing: 1995-05-16
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Granted: 1997-09-23
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Expires: 2015-05-16
Abstract
Abstract This invention involves a prepreg composition and procedure for use in forming printed circuit boards with reduced and uniform dielectric constant, improved thermal expansion characteristics, and uniform appearance. The prepreg composite is a resin impregnated substrate and has a reduced dielectric constant as low as 3.5. It contains 5-30% by resin volume of hollow inorganic microsphere filler whose diameters are less than 40 micrometers, and the uniform distribution of the hollow inorganic microspheres is controlled by the presence of hydrophobic fumed silica or other similar flow modifier.
Inventors
- 👤 Robert J. Sanville, Jr.
- 👤 Carl P. Kernander
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 00:39
CPC Classifications
H; H05; H05K; H05K1/00; H05K1/02; H05K1/03; H05K1/0313; H05K1/0353; H05K1/0373; B; B29; B29C; B29C70/00; B29C70/02; B29C70/021; B29C70/025; B32; B32B; B32B5/00; B32B5/16; C; C08; C08J; C08J5/00; C08J5/24; C08J5/241; C08J5/244; C08J5/249; B29K; B29K2105/00; B29K2105/0005; B29K2105/0026; B29K2105/06; B29K2105/16; B29K2105/165; B29L; B29L2031/00; B29L2031/34; B29L2031/3425; H05K2201/00; H05K2201/01; H05K2201/0104; H05K2201/012; H05K2201/02; H05K2201/0203; H05K2201/0206; H05K2201/0209; H05K2201/0239; Y; Y10; Y10S; Y10S428/00; Y10S428/901; Y10T; Y10T428/00; Y10T428/24; Y10T428/24802; Y10T428/24917; Y10T428/249921; Y10T428/249994; Y10T428/25; Y10T428/27; Y10T428/29; Y10T428/2913; Y10T428/2933; Y10T428/2962; Y10T428/31504; Y10T428/31652; Y10T428/31663
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
51 words
A filled prepreg composite having a uniform reduced dielectric constant comprising: (a) resin; (b) 5-30% by volume of resin solids of hollow inorganic microsphere filler; (c) support material; and (d) sufficient hydrophobic, finely divided silica flow modifier to produce and maintain uniform distribution of the hollow inorganic microspheres in the resin.
Claim 2
Dependent Claim
51 words
A filled prepreg composite having a uniform reduced dielectric constant comprising: (a) resin; (b) 5-30% by volume of resin solids of hollow inorganic microsphere filler; (c) support material; and (d) sufficient hydrophobic, finely divided silica flow modifier to produce and maintain uniform distribution of the hollow inorganic microspheres in the resin.
Claim 3
Dependent Claim
23 words
A prepreg composite as recited in claim 1, wherein the resin includes 2-20% by volume of resin of the hydrophobic, finely divided silica.
Claim 4
Dependent Claim
16 words
A prepreg composite as recited in claim 1, wherein the flow modifier is hydrophobic fumed silica.
Claim 5
Dependent Claim
34 words
A prepreg composite as recited in claim 1, wherein the finely divided silica has been rendered hydrophobic by treatment with a silane compound chosen from the group consisting of: polydimethy-siloxane, dimethyl dichlorosilane, and hexamethydisilazane.
Claim 6
Dependent Claim
27 words
A prepreg composite as recited in claim 1, wherein about 95% of the hollow inorganic microspheres are glass- or silica-walled and have diameters less than 40 micrometers.
Claim 7
Dependent Claim
25 words
A prepreg composite as recited in claim 1, wherein the hollow inorganic micospheres display a compressive strength between 400 and 4,000 lbs. /in 2 .
Claim 8
Dependent Claim
13 words
A prepreg composite as recited in claim 1, further comprising a coupling agent.
Claim 9
Dependent Claim
23 words
A prepreg composite as recited in claim 7, wherein the coupling agent is chosen from the group consisting of: amino-, methacyloxy- and vinyl-silane.
Claim 10
Dependent Claim
19 words
A prepreg composite as recited in claim 1, additionally containing a substance which grants flame retardance to the material.
Claim 11
Dependent Claim
20 words
A prepreg composite as recited in claim 9, wherein the substance which grants flame retardant consists of a halogen compound.
Claim 12
Dependent Claim
24 words
A prepreg composite as recited in claim 10, wherein the substance which grants flame retardance consists of a brominated polyglycidal ether of bisphenol A.
Claim 13
Dependent Claim
24 words
A prepreg composite as recited in claim 11, wherein the resin is an epoxy and the bromine comprises 15-23% by weight of said resin.
Claim 14
Dependent Claim
24 words
A prepreg composite as recited in claim 1, additionally consisting of a UV blocking dye to ensure the composite is opaque to UV light.
Claim 15
Dependent Claim
11 words
A prepreg composite as recited in claim 1, further comprising pigments.
Claim 16
Dependent Claim
27 words
A prepreg composite as recited in claim 14, wherein the resin, hydrophobic finely divided silica, hollow inorganic microspheres, pigments, and support material comprise a flame retardant material.
Claim 17
Dependent Claim
27 words
A prepreg composite as recited in claim 1, wherein said resin is selected from the group consisting of epoxy, cyanate ester, silicone, polyamide, bismaleimide triazine, and urethane.
Claim 18
Dependent Claim
27 words
A prepreg composite as recited in claim 1, wherein said support material is selected from the group consisting of aramid, electronics grade glass, quartz, paper and PTFE.
Claim 19
Dependent Claim
27 words
A conductor-clad substrate made from the composite of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 and 17.
Claim 20
Dependent Claim
28 words
A printed circuit board made from the composite of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17.
Claim 21
Dependent Claim
45 words
A filled prepreg composite having a uniform, reduced dielectric constant, comprising: (a) resin; (b) 5-30% by volume of resin solids of hollow inorganic microsphere filler; (c) support material; and (d) means to produce and maintain uniform distribution of the hollow inorganic microspheres in the resin.
Claim 22
Dependent Claim
45 words
A filled prepreg composite having a uniform, reduced dielectric constant, comprising: (a) resin; (b) 5-30% by volume of resin solids of hollow inorganic microsphere filler; (c) support material; and (d) means to produce and maintain uniform distribution of the hollow inorganic microspheres in the resin.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-09-22 | 2001-03-24 | 2001-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-09-22 | 2005-03-24 | 2005-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-09-22 | 2009-03-24 | 2009-09-23 | $7700.00 | Window Closed / Lapsed |