Browse Prior Art Database

Use of Diffused Infrared Lamp "Heat" for Chip Join-C4 Reflow

IP.com Disclosure Number: IPCOM000106164D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Eisenmann, DE: AUTHOR [+2]

Abstract

This article describes a method to attach semiconductor chips to a ceramic substrate. The controlled chip collapse connection (C4) tech nique is normally accomplished by using a muffle furnace operating at an infrared (IR) wavelength of 2.0-to-5.0 microns. This long wave length IR radiation heats a metal muffle surrounding the substrate, which then heats the environment inside the muffle by conduction and convection, melting the solder of the C4 joint, and thus joining the chip to the substrate.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 60% of the total text.

Use of Diffused Infrared Lamp "Heat" for Chip Join-C4 Reflow

      This article describes a method to attach semiconductor chips
to a ceramic substrate.  The controlled chip collapse connection (C4)
tech nique is normally accomplished by using a muffle furnace
operating at an infrared (IR) wavelength of 2.0-to-5.0 microns.  This
long wave length IR radiation heats a metal muffle surrounding the
substrate, which then heats the environment inside the muffle by
conduction and convection, melting the solder of the C4 joint, and
thus joining the chip to the substrate.

      The method disclosed employs direct IR from an IR lamp to melt
the solder directly by using a diffuse IR heat source.  The present
inven tion is unlike previous methods to melt solder-join chips using
short wavelength (0.65 micron) IR radiation which were focused on the
chip/ substrate by a mirror or a lens to melt the solder.  This
focusing method causes a very high temperature in the chip.  The high
tempera ture can be detrimental to long term reliability of the chip,
causing melting of aluminum lines, or oxidation of all the aluminum
lines, or causing melting of the Cr/Au Base Limiting Metallurgy pads
(BLM).  Many references are available in the literature describing
focused IR beams at wavelengths of 0.65 to 1.5 microns causing this
effect.

      This present invention, however, while using a IR lamp, does
not cause the above problems.  A wavelength of approximately
2.0-to-6.0 microns...