Browse Prior Art Database

High Precision Polishing Technique to Open Electronic Components

IP.com Disclosure Number: IPCOM000100869D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Cazcarra, V: AUTHOR [+4]

Abstract

Disclosed is a process using a high precision polishing machine to perform parallel polishing. This method can be used to remove the epoxy resin from plastic components (flat packs, leaded chip carriers, etc.) and may be helpful for failure analysis, especially in the case of a polyimide passivation. Present opening methods use manual polishing and are therefore operator-dependent.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 88% of the total text.

High Precision Polishing Technique to Open Electronic Components

       Disclosed is a process using a high precision polishing
machine to perform parallel polishing. This method can be used to
remove the epoxy resin from plastic components (flat packs, leaded
chip carriers, etc.) and may be helpful for failure analysis,
especially in the case of a polyimide passivation. Present opening
methods use manual polishing and are therefore operator-dependent.

      The first step of the process consists of preparing the back
side of the chip, which will be used as a reference for polishing.
This step includes removing the epoxy by nitric acid etching until
release of the lead frame below the chip, sawing the die around the
chip, removing the lead frame, and removing the remaining material
attached to the die.

      The second step consists of fixing the chip on the mounting pot
of the polishing machine. In order to avoid as far as possible a
thickness differential, the chip is molded by using epoxy resin. A
thin film of lubricant is necessary to help facilitate chip removal
from the polytetrafluorethylene mold. See Figs. 1 and 2. By using
such a molded chip, the surface in contact with the lapping plate of
the polishing tool is larger and the side effects are minimized.

      The precision polishing phase is monitored by optical
microscopy.  Special attention is required since the top of the ball
bondings are cleared. The polishing is stopped when 5 to 10 um o...