What is Glob Top
Glob top refers to a specialized blob of non-conductive plastic, typically black in color, that is applied to protect the chip and wire bonds on a packaged IC or chip on board. Its primary purpose is to protect the delicate components physically, safeguarding them from external factors such as moisture, dust, and mechanical stress.
The glob top is designed with a low coefficient of thermal expansion, which means it does not significantly expand or contract with changes in temperature. This characteristic is crucial in preventing stress on the wire bonds caused by temperature variations, ensuring their stability and preventing them from becoming loose.
In high-volume chip on board production, the glob top is applied using automated machinery, typically in a round shape. However, during prototype work, the glob top is manually applied, allowing for custom shapes to accommodate specific requirements. It is important to note that the layout of the chip on board is planned to accommodate a round glob top with sufficient tolerance for machine-driven “slop-over” during high-volume production.
By encapsulating the IC or chip on board with the glob top, it not only provides physical protection but also maintains the electrical conductivity of the chip and wire bonds. This is crucial for preserving the functionality and performance of the electronic components.