BOAT FOR BALL ATTACH MANUFACTURING PROCESS AND METHOD OF FABRICATING RELIABLE FLIP-CHIP ASSEMBLY

摘要

A boat (10) onto which solder balls (16) or columns are loaded for an attach process can be used in a universal attach line has a number of attach stations (32-44) to accommodate different types of attach processes. Depending on the process and the desired configuration and form factor of the array of solder balls (16) or columns, a template (14a, 14b) is selected that covers some of the holes (12) in the universal boat (10), and exposes other holes (12). The holes (12) are configured and sized to hold solder balls (16) in the holes (12) such that the solder balls (16) protrude above the top surface of the boat (10) by a predetermined height. This prevents damage to the solder balls (16) while ensuring that the solder balls (16) protrude enough to accommodate imperfectly flat packages that are placed on the array of solder balls (16) held in the boat (10). Vacuum applied through the holes (12) help to securely hold the balls (16) in place, and a substrate (18) is placed onto the solder balls (16). Once loaded with balls (16) or columns, the boat (10) is transported to only the appropriate attach stations in the universal attach line, where the different attach operations for a given attach process, such as high temperature ball attach, eutectic ball attach, or column attach, are performed. Also provided is a method of fabricating laminate assemblies that determines the ideal weight (W) of underfill to be dispensed, based on the size of the semiconductor die (144) and the gap (142) between the die (144) and the laminate substrate. Underfill (150) is dispensed in a single step in an amount between 1.1W and 1.3W to form fillets (52, 54) that cover at least 15% of the height of the semiconductor die (144) on all four sides of the die. The amount of underfill (150) ensures that the fillet coverage imbalance is 30% or less for each of the pairs of opposing sides of the die (144), thereby improving solder joint reliability.