Instruction 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.
Item Description
1 Flip Chip
2 First Pass of L-shaped Pattern
3 Second Pass of L-shaped Pattern
4 U-shaped Pattern
5 First Underfill Pass
6 Second Underfill Pass
7 U-shaped Seal Pass
Figure 9-2
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3
5
6
4
1
7