Multi-layer circuit board bonding method utilizing noble metal coated surfaces
First Claim
1. A method of forming an electrically and mechanically sound joint between internal layers of a multi-layer plated through hole printed circuit board comprising the steps of:
- applying a coating of a noble metal to layer surfaces to be conductively joined on the through hole board layers;
juxtaposing the noble metal coated surfaces on the through hole board layers;
applying a layer of thermal adhesive over the outer surfaces of the juxtaposed through hole board layers;
juxtaposing imperforate outer board layers over the adhesive layers; and
exposing the juxtaposed layers to a pressure from about 100 psi to about 10,000 psi and a temperature from about 400 to about 1000 degrees F. until the noble metal coated surfaces bond to form an electrically and mechanically sound metal to metal joint and thermal adhesive is extruded into the through holes of the internal through hole board layers, thereby forming a multi-layer board with buried through hole interconnections.
1 Assignment
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Accused Products
Abstract
An electrically and mechanically sound conductive bond between layers of a multi-layer plated through hole circuit board is produced by depositing a layer of noble metal over the surfaces to be joined, juxtaposing the noble metal coated layers and subjecting them to a combination of pressure and heat for a sufficient period of time. Excellent results have been obtained in a multi-layer circuit board for a microstrip microwave antenna with 0.002 inch thick polished silver layers at bonding pressures of 490 to 575 psi and temperatures of 560 to 580 degrees F. for time periods of 20 to 30 minutes.
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Citations
25 Claims
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1. A method of forming an electrically and mechanically sound joint between internal layers of a multi-layer plated through hole printed circuit board comprising the steps of:
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applying a coating of a noble metal to layer surfaces to be conductively joined on the through hole board layers; juxtaposing the noble metal coated surfaces on the through hole board layers; applying a layer of thermal adhesive over the outer surfaces of the juxtaposed through hole board layers; juxtaposing imperforate outer board layers over the adhesive layers; and exposing the juxtaposed layers to a pressure from about 100 psi to about 10,000 psi and a temperature from about 400 to about 1000 degrees F. until the noble metal coated surfaces bond to form an electrically and mechanically sound metal to metal joint and thermal adhesive is extruded into the through holes of the internal through hole board layers, thereby forming a multi-layer board with buried through hole interconnections. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 20, 21, 22, 23, 24)
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15. A method of forming an electrically and mechanically sound joint between internal layers of a multi-layer plated through hole printed circuit board comprising the steps of:
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applying a coating of silver to the layer surfaces to be joined by electroplating at a current density of from about 2 to about 10 amp/ft2 for a period from about 15 minutes to about 12 hours; juxtaposing the noble metal coated surfaces; exposing the juxtaposed layers to a pressure from about 100 psi to about 10,000 psi and a temperature from about 400 to about 1000 degrees F. until the noble metal coated surfaces bond to form an electrically and mechanically sound metal to metal joint.
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16. A method of forming an electrically and mechanically sound joint between internal layers of a multi-layer plated through hole printed circuit board comprising the steps of:
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applying a coating of a noble metal to the layer surfaces to be joined; juxtaposed the noble metal coated surfaces; and exposing the juxtaposed layers to a pressure from about 100 psi to about 10,000 psi and a temperature from about 400 to about 1000 degrees F. until the noble metal coated surfaces bond to form an electrically and mechanically sound metal to metal joint; wherein an adhesive is interposed between surfaces of juxtaposed circuit board layers not coated with noble metal, and an adhesive bond is formed between such layers during the exposure of the layers to pressure and heat. - View Dependent Claims (17)
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18. A method of forming an electrically and mechanically sound joint between internal layers of a multi-layer plated through hole printed circuit board comprising the steps of:
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applying a coating of a noble metal to the layer surfaces to be joined; polishing the noble metal coating; juxtaposing the noble metal coated surfaces; and exposing the juxtaposed layers to a pressure from about 100 psi to about 10,000 psi and a temperature from about 400 to about 1000 degrees F. until the noble metal coated surfaces bond to form an electrically and mechanically sound metal to metal joint. - View Dependent Claims (19)
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25. A multi-layer plated through hole printed circuit board with buried through hole interconnections produced by a process comprising the steps of:
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applying a coating of a noble metal to layer surfaces to be conductively joined on the through hole board layers; juxtaposing the noble metal coated surfaces on the through hole board layers; applying a layer of thermal adhesive over the outer surfaces of the juxtaposed through hole board layers; juxtaposing imperforate outer board layers over the adhesive layers; and exposing the juxtaposed layers to a pressure from about 100 psi to about 10,000 psi and a temperature from about 400 to about 1000 degrees F. until the noble metal coated surfaces bond to form an electrically and mechanically sound metal to metal joint and thermal adhesive is extruded into the through holes of the internal through hole board layers.
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Specification