Underfill Encapsulation analysis

The Underfill Encapsulation analysis is used to analyze the flow of the encapsulant material in the cavity, between the chip and the substrate during the underfill encapsulation process.

Flip chips are sometimes used for high-density electronic packaging. Flip chips offer the advantage of an area array which interconnects the chip and substrate.

A weakness in the flip chip process is the solders that typically connect the chip to the board. During service, the solders can be damaged, mainly from the stresses associated with the temperature change of the package.

Underfill encapsulation is the process of filling the cavity between the chip and the substrate with a thermoset encapsulant. This helps to protect the solders during service.

In most cases, underfill encapsulation is done by dispensing the encapsulant material along the periphery of the chip. Capillary force drives the encapsulant through the space between the chip and the board.

During Underfill Encapsulation, each injection location is open at a different time because of the time delay when the dispensing head moves around the edge of the chip for the dispensing. It is often common to find that dispensing is done over several passes to avoid excessive spreading of encapsulant in the dispensing area when a large amount of encapsulant is dispensed all at once. This is known as dynamic dispensing. The Dynamic Dispensing analysis option in the Process Settings Wizard enables you to simulate this situation.