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Bonding Cu Terminals to Al Posts on Aluminum Electrolytic Capacitors

IP.com Disclosure Number: IPCOM000040787D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Pratt, JD: AUTHOR [+3]

Abstract

Described is a method to overcome the oxidation and corrosion of aluminum material at the terminals of large can capacitors. It proposes the incorporation of a copper cap bonded to and envelopin a redesigned aluminum post.

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Bonding Cu Terminals to Al Posts on Aluminum Electrolytic Capacitors

Described is a method to overcome the oxidation and corrosion of aluminum material at the terminals of large can capacitors. It proposes the incorporation of a copper cap bonded to and envelopin a redesigned aluminum post.

In the conventional large can aluminum capacitors, the aluminum posts are subject to oxidation, corrosion and creep of the Al. In a conventional design, shown in Fig. 1A, the Al post 1 protrudes through a plastic coating 2 and is threaded 3 to receive a steel connecting screw. In the modification, shown in Fig. 1B, a newly designed Al post 4 is covered with a Cu cap 5 threaded 3 to receive the connecting screw.

The key dimension "A" (Fig. 1B) requires that the internal diameter of the cap be slightly greater than the diameter of the Al post. In assemblying the unit, the Al post and Cu cap are cleaned with appropriate etchants. They are assembled together and heat treated in a reducing environment at an elevated tem- perature for an appropriate period of time. This then affords a metallurgical bond 6 (Fig. 1B) to the assembly.

The Cu cap makes the Al post much more reliable as a termi- nal than heretofore. Consideration may also be given to making solder connections to the Cu cap, thereby doing away with the screwed connection.

Disclosed anonymously

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