Browse Prior Art Database

Process to Join JEDEC Chip Carriers to MLC

IP.com Disclosure Number: IPCOM000049610D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

DeBoskey, WR: AUTHOR [+6]

Abstract

This article describes techniques for joining chip carriers to multilayer ceramic (MLC) substrates and for reworking such chip carriers. Briefly, the technique for joining the chip carriers to the substrate uses a two-step paste deposition process and a double reflow step process at higher than conventional temperatures. The rework techniques include the use of an aluminum block to provide localized heating prior to removal of a defective carrier and the step of screening solder paste onto the bottom of new chip carriers under certain conditions instead of onto the substrate.

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Process to Join JEDEC Chip Carriers to MLC

This article describes techniques for joining chip carriers to multilayer ceramic (MLC) substrates and for reworking such chip carriers. Briefly, the technique for joining the chip carriers to the substrate uses a two-step paste deposition process and a double reflow step process at higher than conventional temperatures. The rework techniques include the use of an aluminum block to provide localized heating prior to removal of a defective carrier and the step of screening solder paste onto the bottom of new chip carriers under certain conditions instead of onto the substrate.

In more detail, the technique for joining chip carriers to an MLC substrate includes the following steps: 1) In a first pass, approximately 6 mils of Sn/Pb solder paste

are screened onto gold/nickel contacts on the substrate.

2) The substrate is heated to 250 degrees -260 degrees C to

produce reflow between the solder paste and the gold layer.

3) In a second pass, approximately 4 mils of solder paste are

screened onto the contact areas.

4) The chip carriers are placed on the substrate.

5) The assembly is heated to 250 degrees -260 degrees C to

produce reflow.

6) The assembly is cleaned by dipping, agitating and drying.

The advantages of the subject process are that no standoff is required to produce a gap between the substrate and the bottom of the chip carrier, few solder balls are created, and the bond between the chip carrier and substrate is str...