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Pin Design for Attaching Pins to a Ceramic Package by Means of a Solder without Solder Climb on to the Pin Shank

IP.com Disclosure Number: IPCOM000109900D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Farooq, S: AUTHOR [+4]

Abstract

The attachment of pins coated with a suitable wetting metallurgy (e.g., Au) to a ceramic substrate by means of a Sn-based solder is confounded by the problem of solder climb onto the pin shank. Since good electrical contact with the pin shank requires the presence of a Au coating on the pin shank, some means of preventing the solder from coming in contact with this Au is required for successful pin attachment. A modified design for coating the pin is proposed here to overcome this problem.

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Pin Design for Attaching Pins to a Ceramic Package by Means of a Solder without Solder Climb on to the Pin Shank

       The attachment of pins coated with a suitable wetting
metallurgy (e.g., Au) to a ceramic substrate by means of a Sn-based
solder is confounded by the problem of solder climb onto the pin
shank.  Since good electrical contact with the pin shank requires the
presence of a Au coating on the pin shank, some means of preventing
the solder from coming in contact with this Au is required for
successful pin attachment.  A modified design for coating the pin is
proposed here to overcome this problem.

      A schematic of a typical pin is shown in Fig. 1.  Four regions
A, B, C, and D are shown.  The key element of this method is to
maintain a surface that exhibits poor wettability to the solder in
region B.  It is preferred that region A have a Au coating for good
electrical contact.  Also, it is preferred that region D and,
optionally, region C have some wettable coating (e.g., Au) to provide
good bonding and wettability to the solder.  Examples of the coatings
in each of the above regions are given in Table 1.

      While we are not limited to any specific method for producing
the above coating schemes, the overall process could involve a
combination of coating techniques, e.g., electro or electroless
plating, sputter deposition, and evaporation.  For example, Scheme 1
(Table 1) could be implemented by first plating all the regions
uniformly...