Semiconductor Package Trench Structure for Underfill Bleeding Control
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Solution Overview
Problem
The underfill material in semiconductor packages often bleeds outside during the mounting process, leading to poor mounting of electronic elements and reduced reliability of solder ball connections, causing defects and reliability issues.
Innovation Solution
A semiconductor package design that includes a redistribution layer structure with a protective layer having a trench and an under-bump metal layer, where the underfill material fills the space between the under-bump structure and the electronic element, and the trench surrounds the electronic element with protrusion portions to control bleeding, thereby preventing defects and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If underfill material is applied to improve reliability of electronic elements, then reliability is improved, but underfill material bleeds outside causing mounting defects and solder ball connection deterioration
Solution Approach 1:
The protective layer is segmented into multiple functional zones: a first region that allows underfill material passage, a second region that blocks underfill material, and a third region that provides structural support. This segmentation enables the underfill material to be directed along a controlled path to the electronic element while preventing it from bleeding outside the designated area, thus resolving the contradiction between improving reliability and maintaining mounting precision.
Solution Approach 2:
The protective layer acts as an intermediary structure between the underfill material application point and the electronic element. It includes a first region that serves as a controlled passage way for the underfill material, guiding it to the intended location without allowing lateral spreading. This intermediary structure enables the underfill material to reach the electronic element for reliability improvement while preventing the bleeding that would cause mounting defects.
2Strength
If underfill material is applied to fill space between under-bump structure and electronic element, then mechanical support is improved, but underfill material spreads uncontrollably causing mounting defects
Solution Approach 1:
The protective layer is segmented into a first region that permits underfill material passage and a second region that prevents passage. This segmentation creates a controlled flow path that allows the underfill material to fill the space between the under-bump structure and electronic element for mechanical support, while the second region acts as a boundary that prevents uncontrolled spreading and maintains mounting precision.
Solution Approach 2:
Different regions of the protective layer have different local qualities regarding material permeability. The first region has high permeability to allow underfill material to reach the electronic element and provide mechanical support, while the second region has low or zero permeability to prevent lateral spreading. This local quality differentiation enables the underfill material to fulfill its mechanical support function without causing mounting defects from uncontrolled spreading.
Data Source
AI summary
A semiconductor package may include a redistribution layer structure including a redistribution layer, a semiconductor chip a first surface of the redistribution layer structure, an under-bump structure disposed on a second surface of the redistribution layer structure and including a protective layer having a trench and an under-bump metal layer, an electronic element on the under-bump structure, and an underfill member filling at least a portion of a space between the under-bump structure and the electronic element and filling at least a portion of the trench, wherein, in a plan view, the trench surrounds the electronic element and may include a protrusion portion protruding outward from the electronic element in a region surrounding an edge of the electronic element.