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Browse Prior Art Database

METHOD TO PREVENT REFLOW OF LOW TEMPERATURE SOLDER PACKAGES

IP.com Disclosure Number: IPCOM000004647D
Publication Date: 2001-Mar-15
Document File: 1 page(s) / 123K

Publishing Venue

The IP.com Prior Art Database

Abstract

A Method is disclosed here that allows lead frame/substrate bond sites to be wire bonded at higher temperatures while the area underneath the die/chip (which can include the die/chip attach material) is at a temperature below the leadframe/substrate bond sites. An example of ( but certainly not limited to) where this method would be useful over existing methods is in a aluminum-copper metal system for copper ball bonding where the typical epoxy Tg and solder reflow levels are lower than the temperature required for copper wire bond.

This text was extracted from a WORD97 document.
This is the abbreviated version, containing approximately 100% of the total text.

METHOD TO PREVENT REFLOW OF LOW TEMPERATURE SOLDER PACKAGES

A Method is disclosed here that allows lead frame/substrate bond sites to be wire bonded at higher temperatures while the area underneath the die/chip (which can include the die/chip attach material) is at a temperature below the leadframe/substrate bond sites. An example of but certainly not limited to) where this method would be useful over existing methods is in a aluminum-copper metal system for copper ball bonding where the typical epoxy Tg and solder reflow levels are lower than the temperature required for copper wire bond.

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A delta temperature is maintained from the lead frame/substrate bond site(s) to the die/chip by using a material of different thermal conductivity in the area of contact for the die/chip. In this manner the temperatures of the die, chip, or leadframe, or attachment materials, or bond areas can be altered or selected by using different thermal conductivity materials.

In one example of the concept (see drawing below) a ceramic insert is used in the area of the die paddle on a Shinkawa UTC-100 packaging tool. Due to the difference in thermal conductivity between the ceramic and the metal heater block the chip/die area will be cooler than the leadframe/substrate bond sites. This insures the die/chip attach bond strength dose not become affected deleteriously.