Demonstration of fine pitch FCOB (Flip Chip on Board) assembly based on solder bumps at Fermilab

TL;DR

This paper demonstrates a successful flip chip on board assembly using solder bumps at Fermilab, achieving a 250um pitch, which improves connection reliability and reduces parasitic effects for high-density applications.

Contribution

It presents the first successful demonstration of FCOB assembly with solder bumps at 250um pitch, including assembly procedure and initial contact resistance measurements.

Findings

Successful FCOB assembly at 250um pitch

Microscopic analysis of solder bump connections

Initial contact resistance measurements reported

Abstract

Bump bonding is a superior assembly alternative compared to conventional wire bond techniques. It offers a highly reliable connection with greatly reduced parasitic properties. The Flip Chip on Board (FCOB) procedure is an especially attractive packaging method for applications requiring a large number of connections at moderate pitch. This paper reports on the successful demonstration of FCOB assembly based on solder bumps down to 250um pitch using a SUESS MA8 flip chip bonder at Fermilab. The assembly procedure will be described, microscopic cross sections of the connections are shown, and first measurements on the contact resistance are presented.