Browse Prior Art Database

Solder Bump-Making Process

IP.com Disclosure Number: IPCOM000035888D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Arimoto, Y: AUTHOR

Abstract

This process is used to deposit solder bumps on a printed circuit board. The board with solder bumps is to be used as a carrier for the DCA (Direct Chip Attach) application, as shown in Fig. 1. The following is a specific example of the process.

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Solder Bump-Making Process

This process is used to deposit solder bumps on a printed circuit board. The board with solder bumps is to be used as a carrier for the DCA (Direct Chip Attach) application, as shown in Fig. 1. The following is a specific example of the process.

Liquid photosensitive solder resist 1 is applied on the surface of the printed circuit board 2. The solder resist is patterned using conventional photoresist techniques to obtain the Fig. 2 structure. A thin copper layer 3 is then plated on top of the board 2, as shown in Fig. 3, in order to do electrolytic tin/lead plating in the subsequent process.

The areas not to be electroplated are covered with a dry film photoresist layer 4 applied by conventional techniques, as shown in Fig. 4.

Eutectic solder 5 is then electroplated to make the Fig. 5 structure. The photoresist 4 is stripped and the copper layer 3 is then removed at the regions under the photoresist 4 by an ammonium chloridebased etching solution to produce the final structure of Fig. 6.

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