Composite organic encapsulants

• US 8,233,261 B2
• Filed: 12/11/2007
• Issued: 07/31/2012
• Est. Priority Date: 12/12/2006
• Status: Active Grant

• Current Assignee: Chemtron Research LLC (Intellectual Ventures LLC)
• Original Assignee: Cda Processing LLC (Intellectual Ventures LLC)
• Inventors: Summers, John D, Mutoh, Tsutomu
• Primary Examiner(s): THOMAS, ERIC W
• Application Number:
  US12/514,822
• Publication Number:
  US 20100067168A1
• Time in Patent Office: 1,694 Days
• Field of Search: 361311-313, 361/301.4, 361761-763
• US Class Current: 361/301.3
• CPC Class Codes: H01G 4/224 Housing; Encapsulation
• CPC Class Codes: H01L 23/50 for integrated circuit devices, e.g. power bus, number of leadsH01L23/482 - H01L23/498 take precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05K 1/162 incorporating printed capacitors
• CPC Class Codes: H05K 2201/0154 Polyimide
• CPC Class Codes: H05K 2201/0158 Polyalkene or polyolefin, e.g. polyethylene [PE], polypropylene [PP]
• CPC Class Codes: H05K 2201/0187 with regions of different dielectrics in the same layer, e.g. in a printed capacitor for locally changing the dielectric properties
• CPC Class Codes: H05K 2201/0355 Metal foils
• CPC Class Codes: H05K 2201/09763 Printed component having superposed conductors, but integrated in one circuit layer
• CPC Class Codes: H05K 2203/1126 Firing, i.e. heating a powder or paste above the melting temperature of at least one of its constituents
• CPC Class Codes: H05K 3/1291 Firing or sintering at relative high temperatures for patterns on inorganic boards, e.g. co-firing of circuits on green ceramic sheets

Abstract

This invention relates to compositions, and the use of such compositions for protective coatings, particularly of electronic devices. The invention concerns a fired-on-foil ceramic capacitors coated with a composite encapsulant and embedded in a printed wiring board.

Claims

1. An organic two-layer encapsulant composition for coating one or more embedded formed-on-foil ceramic capacitors, said two-layer encapsulant comprising a first encapsulant layer and a second encapsulant layer wherein said first encapsulant layer comprises (a) a polyimide and said second encapsulant layer comprises (b) an epoxy-containing cyclic olefin resin, (c) a phenolic resin, (d) an epoxy catalyst;

and wherein said embedded formed-on-foil ceramic capacitors comprise a capacitor element and a prepreg wherein said first encapsulant layer is in direct contact with said capacitor element and said second encapsulant layer is in direct contact with said first encapsulant layer.

2. The organic two-layer encapsulant composition of claim 1 wherein the polymide has a water absorption of 2% or less and a glass transition temperature greater than 280°

C.

3. The organic two-layer encapsulant composition of claim 1 wherein the epoxy-containing cyclic a olefin resin has a water absorption of 2% or less.

4. The organic two-layer encapsulant composition of claim 1 wherein the phenolic resin has a water absorption of less than 2%;

an epoxy catalyst;

optionally one or more of an electrically insulated filler, a defoamer and a colorant and one or more organic solvents.

5. The organic two-layer encapsulant composition of claim 1 wherein said first encapsulant layer further comprises one or more components selected from the group comprising an electrically insulated filler, a defoamer, a colorant, an epoxy resin, and mixtures thereof.

6. The encapsulant composition of claim 1 wherein said encapsulant composition is cured to form a two-layer organic encapsulant and wherein said cured two-layer organic encapsulant provides protection to the capacitor when immersed in sulfuric acid or sodium hydroxide having concentrations of up to 30%.

7. The encapsulant composition of claim 1 wherein said encapsulant composition is cured to form a two-layer organic encapsulant and wherein the cured two-layer organic encapsulant provides protection to the capacitor in an accelerated life test of elevated temperatures, humidities and DC bias.

8. The encapsulant composition of claim 1 wherein the encapsulant composition is used to fill an etched trench that isolates the top and bottom electrodes of an embedded capacitor.

9. The encapsulant composition of claim 1 wherein said encapsulant composition is cured to form a cured organic encapsulant and wherein the water absorption is 1% or less.

10. The encapsulant composition of claim 1 wherein the composition can be cured at a temperature of less than or equal to 190°

C.

11. The encapsulant composition of claim 1 wherein said encapsulant is cured to form a cured organic encapsulant and wherein the adhesion of said encapsulant to the capacitor and to the prepreg above the capacitor is greater than 2 lb force/inch.