Ring-opening-induced toughening of a low-permittivity polymer-metal interface.
Integrating low dielectric permittivity (low-k) polymers to metals is an exacting fundamental challenge because poor bonding between low-polarizability moieties and metals precludes good interfacial adhesion. Conventional adhesion-enhancing methods such as using intermediary layers are unsuitable for engineering polymer/metal interfaces for many applications because of the collateral increase in dielectric permittivity. Here, we demonstrate a completely new approach without surface treatments or intermediary layers to obtain an excellent interfacial fracture toughness of >13 J/m(2) in a model system comprising copper and a cross-linked polycarbosilane with k approximately 2.7 obtained by curing a cyclolinear polycarbosilane in air. Our results suggest that interfacial oxygen catalyzed molecular ring-opening and anchoring of the opened ring moieties of the polymer to copper is the main toughening mechanism. This novel approach of realizing adherent low-k polymer/metal structures without intermediary layers by activating metal-anchoring polymer moieties at the interface could be adapted for applications such as device wiring and packaging, and laminates and composites.
Singh
B
B
Garg
S
S
Rathore
J
J
Moore
R
R
Ravishankar
N
N
Interrante
L
L
Ramanath
Ganpati
G
D003300:Copper / Q000737:chemistry*; D017097:Electric Impedance; D006244:Hardness; D008420:Manufactured Materials / Q000032:analysis*; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties
D011108:Polymers; D003300:Copper