Non-Conductive paste (NCP) is used to reinforce area array connections, which are typically gold stud bump type connections. An adhesive is placed on the surface of a substrate and the die with the gold bumps is pushed into the adhesive to make contact with the substrate metalized pads. Themocompression bonding of the die connections create the electrical connections to and the heat from the process cures the adhesive in the same step. The adhesive now acts as an underfill material. It has been reported that this process can also be used with solder ball attachment and the adhesive acts as a flux to remove oxide from the metal contacts.
No-flow underfill is a similar process where an adhesive is dispensed onto a substrate. A die with solder bumps is pushed through the adhesive and is held in place as the assemblies solder bumps are reflowed in an oven. The adhesive first acts as a flux and is converted to an adhesive underfill during reflow.
In either case Nordson ASYMTEK systems can dispense the materials for these applications. Our process knowledge about how the material needs to be dispensed and what type of pattern to use are crucial to a successful interconnection being formed with high reliability.