Polymer Degradation Mechanics in Glass-Filled Injection Tooling Cavities
Glass fiber erosion and shear scission alter gate dimensions and matrix integrity, requiring modular PM steel inserts and strict vent land depth maintenance.
Micro-Corrosion
Meaning
Localized chemical degradation occurs on a microscopic scale at the interfaces of metallic contacts and thin film traces. In the context of microelectronics, micro-corrosion involves the slow dissolution of metal atoms due to the presence of moisture and ionic contaminants. This process can lead to high resistance or open circuits in the delicate wiring of a semiconductor package.
Intermetallic Interface
Different metals used in bond pads and wires create a galvanic cell when exposed to an electrolyte. Gold and aluminum interfaces are particularly susceptible to this type of decay if the protective coating is compromised.
Environmental Sensitivity
Humidity and temperature are the main drivers of the reaction rate in a finished product. Even hermetically sealed packages can harbor small amounts of trapped moisture that initiate the decay over long periods. Testing protocols often include biased humidity trials to accelerate these effects and identify weaknesses in the passivation layers.
Understanding the transition from an atmospheric vapor to a liquid electrolyte is necessary for predicting the start of the corrosive process.
Reliability Risk
Failures caused by these small-scale reactions are difficult to detect because they often occur intermittently before the connection breaks completely. A system might pass initial inspection but develop faults after several months of use in a humid environment. Using noble metals or improved sealing techniques are common methods for reducing the probability of these events.