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Browse Prior Art Database

Non-Degradable I/O Connections for MLC Structures

IP.com Disclosure Number: IPCOM000043959D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Master, RN: AUTHOR [+2]

Abstract

This article describes a method and a process for attaching input/ output pins to the bottom surface of MLC (multilayer ceramic) and MLC systems fabricated from glass-ceramic and copper. I/O connections external to MLC substrates consist of pins (KOVAR*) which are brazed with a gold/tin braze to pre-deposited metal pads on the bottom of the ceramic substrate. Strong pad adhesion to the ceramic is necessary in order that the pins have the proper pull strength (N10 to 12 pounds per pin on a system fabricated from ceramic and molybdenum).

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Non-Degradable I/O Connections for MLC Structures

This article describes a method and a process for attaching input/ output pins to the bottom surface of MLC (multilayer ceramic) and MLC systems fabricated from glass-ceramic and copper. I/O connections external to MLC substrates consist of pins (KOVAR*) which are brazed with a gold/tin braze to pre-deposited metal pads on the bottom of the ceramic substrate. Strong pad adhesion to the ceramic is necessary in order that the pins have the proper pull strength (N10 to 12 pounds per pin on a system fabricated from ceramic and molybdenum). When an MLC system is fabricated from ceramic and copper, however, a bonding mechanism which will provide bond strengths comparable to that of the glass-ceramic and molybdenum system is very difficult to obtain because of the significant mismatch encountered in temperature coefficients of expansion between the ceramic material and copper. The disclosed method and process eliminate the pin brazing problem identified above by first embedding the copper pins in a separate sublaminate (see lower section of illustration) structure. The upper section of the illustration shows another sublaminate structure which contains the complete MLC wiring plane assembly. Both sublaminate structures are assembled in green sheet phase prior to being later joined in a final lamination and sintering operation. The pins thus become an integral part of the MLC substrate structure with a significantly incre...