User Manual

9-4 Advanced Programming
Underfill Patterns
There are several types of line patterns used for underfill applications. Two common types
are L-shaped and U-shaped patterns as shown in Figure 9-2 Variations of these types of
underfill patterns are used as well. These patterns and processes are designed to assure
complete underfilling without excess and to prevent voids in the underfill.
Figure 9-2
flip chip
L-shaped Pattern
U-shaped Pattern
Underfill Passes
Seal Pass
First Pass
2
1
U-shaped
Seal Pass