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Ceramic Chip Capacitor Fusing Mechanism

IP.com Disclosure Number: IPCOM000039152D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Morrison, JD: AUTHOR [+2]

Abstract

An internal fusing mechanism is disclosed for fused ceramic chip capacitors used in semiconductor devices. The internal aspect, as opposed to conventional externally fused devices, permits the part to be dipped in SnBi solder. Ceramic bulk decoupling capacitors designated by 1 in Fig. 1 are used for high frequency applications due to their inherently high resonant frequencies. The internal fuse mechanism designated by elements 2, 3 and 4 is surmounted with a protective coating 5, with the plates 6 of the capacitor surrounded with a Pd/Ag paste 7. A Ni barrier 8 and Au coating 9, to prevent oxidation, complete the capacitor which may then be dipped in Sn/Bi solder 10. (Image Omitted) The structure of the fuse mechanism, shown in Fig. 2, includes Ti/W 2, Al 3, and Pd/Ru 4.

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Ceramic Chip Capacitor Fusing Mechanism

An internal fusing mechanism is disclosed for fused ceramic chip capacitors used in semiconductor devices. The internal aspect, as opposed to conventional externally fused devices, permits the part to be dipped in SnBi solder. Ceramic bulk decoupling capacitors designated by 1 in Fig. 1 are used for high frequency applications due to their inherently high resonant frequencies. The internal fuse mechanism designated by elements 2, 3 and 4 is surmounted with a protective coating 5, with the plates 6 of the capacitor surrounded with a Pd/Ag paste 7. A Ni barrier 8 and Au coating 9, to prevent oxidation, complete the capacitor which may then be dipped in Sn/Bi solder 10.

(Image Omitted)

The structure of the fuse mechanism, shown in Fig. 2, includes Ti/W 2, Al 3, and Pd/Ru 4. These may be applied through evaporation in the same vacuum chamber with two sets of masks required. The fuse connects with the Pd/Ag paste 7 surrounding the capacitor (Fig. 1). Should the dielectric separating the plates of the capacitor fail, large amounts of current will flow through the flaw and then through the fuse. When the temperature of the fuse reaches 650~C, the dissimilar metals Al/Pd undergo an exothermic reaction and totally disintegrate. The TiW separation layer 2 between the Pd/Ag 7 and Al 3 (Fig. 2) serves to lower the equivalent series resistance and prevents silver migration after the fuse has blown. The internal fusing mechanism provides...