Heat seal connectors: a new high density SMT interconnection system

Most conventional electronic products use liquid-crystal displays (LCDs) to display information. The introduction of the heat seal connector, which uses a conductive adhesive system as the bridge to connect the board substrate and the LCD, has been shown to result in an order of magnitude reduction in size with a corresponding increase in reliability while reducing overall product cost as compared with the older-technology elastomer interconnect systems. These new interconnect systems are capable of connecting traces as close as 0.004-in. centers, and the new thin-film versions are capable of interconnections as fine as 180 lines per inch. Much development work has been done in quantifying the key processing parameters necessary to achieve the required bond strength for high-reliability, industrial-rated electronic devices. The key processes that were developed to obtain the required bond strength, how these bonds were stress-tested to verify field reliability, and what was needed to introduce this new interconnecting technique to the factory are discussed