With the shrinking size and increasing density of electronic packages, reliability becomes one of the most critical issues. Especially delamination, such as the weak adhesion between copper substrate and epoxy encapsulation, is prone to happened in high temperature and high moisture environment typified by the ageing test undergone by integrated circuit packages....[ Read more ]

With the shrinking size and increasing density of electronic packages, reliability becomes one of the most critical issues. Especially delamination, such as the weak adhesion between copper substrate and epoxy encapsulation, is prone to happened in high temperature and high moisture environment typified by the ageing test undergone by integrated circuit packages.

In order to solve this problem, thiol-based self-assembly material of different chemical configurations is applied to serve as coupling agent between copper and epoxy. This thesis focuses on studying the behavior of copper/epoxy interface reliability under moisture condition with the thiol-based material treatments. Two main aspects studied in this thesis are 1) treatment conditions and process and 2) thiol material configurations.

Parameters of treatment condition mainly include the treatment time and solution concentration. For the thiol materials, three effects are studies: the functional group that reacts with epoxy, backbone structures (alkane chain structure and benzene ring structure), and chain length of alkanethiol.

Adhesion strength is tested with the tapered double cantilever beam (TDCB) test setup, and fracture toughness (G_IC) is calculated for comparison. Moisture reliability is tested by applying the moisture sensitivity level 1 (MSL 1) standard, which is 85℃/85RH for 168 hour. Thermal stability is also evaluated. With the SAM H treatment, best adhesion is recorded at 244.4±39.5J/m². Compared with control one, which adhesion is only 4.8± 0.8J/m², a 50 fold improvement is demonstrated.

To have better understanding of the thiol coating and fracture enhancement, surface characterization and investigation of fracture surface are carried out. Molecular dynamic (MD) simulation is conducted to evaluate the theoretical bonding energy of the interface with thiol layer of different structures. Correlation between the surface hydrophobicity and the moisture reliability for the alkanethiols are found. Optimum chain lengths for each of the alkanethiol structures are also determined.