Browse Prior Art Database

Replaceable Engineering Change Pad

IP.com Disclosure Number: IPCOM000078543D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Simek, JG: AUTHOR

Abstract

In large-scale integrated circuit (LSI) packages (Fig. 1), semiconductor chips 1 mounted on a module 2 are provided with metal pads 3 to which discrete wires 4 can be bonded, in order to accommodate engineering changes. The pads are electrically connected to the chips via internal module wiring patterns 6. The discrete wires are ultrasonically bonded to the pads, preferably without stripping the insulation from the wire ends. Only a small number of such bondings to a pad can be made before it is rendered unusable.

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Replaceable Engineering Change Pad

In large-scale integrated circuit (LSI) packages (Fig. 1), semiconductor chips 1 mounted on a module 2 are provided with metal pads 3 to which discrete wires 4 can be bonded, in order to accommodate engineering changes. The pads are electrically connected to the chips via internal module wiring patterns 6. The discrete wires are ultrasonically bonded to the pads, preferably without stripping the insulation from the wire ends. Only a small number of such bondings to a pad can be made before it is rendered unusable.

During the ultrasonic bonding process, a physical interaction occurs between the wire and the bonding pad which greatly reduces the possibility of further successful bonding on that same specific area.

The bonding process is cost reduced by not having to strip the TEFLON* coated wire, but this reduces the probability of getting additional bonds to successfully adhere to the module pad, since the wire insulation tends to contaminate the pad area and hampers the next bond.

Fig. 2 shows a simple, economic solution to the problem, i.e., attaching a metal chip 3a to the original pad 3 by solder 5 and bonding the wire 4 to the chip 3a. The chips 3a are replaced by new chips when they become unusable. Without a suitable solution to the pads 3 becoming unusable, the following problems result:
1) When a module pad is "used up", the expensive module is

rendered useless.
2) It is then necessary to know the repair status of every...