Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Fine-Pitch Solder Ball Formation

IP.com Disclosure Number: IPCOM000106357D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Kinoshita, S: AUTHOR [+2]

Abstract

Disclosed is a process for forming fine-pitch solder balls on a chip. A polyimide layer which is blanket deposited after formation of the solder balls and reduced in thickness by plasma etching is used for solder ball isolation.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Fine-Pitch Solder Ball Formation

      Disclosed is a process for forming fine-pitch solder balls on a
chip.  A polyimide layer which is blanket deposited after formation
of the solder balls and reduced in thickness by plasma etching is
used for solder ball isolation.

      In this process, solder is deposited on BLM (Ball Limiting
Metal) structure on a chip and reflowed to form solder balls.  Then
liquid polyimide is applied on the entire surface by any suitable
method such as spin coating or brush coating.  Blanket etching,
preferably O2 ashing, is performed to reduce thickness of the
polyimide layer and expose top portions of the solder balls.
Finally, curing of the polyimide is performed for stabilization.

      The polyimide spacer can absorb transformation of the solder
balls in chip joining step without collapse and play a physical
barrier or isolator, enabling use of finer pitch solder balls for
chip jining.