Circuit Board Trenches for Underfill Void Prevention
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Solution Overview
Problem
Voids and air traps in the underfill between semiconductor devices and circuit boards lead to electrical separation when exposed to high temperatures, causing device failure.
Innovation Solution
A circuit board design with trenches in the protective layer to expose conductive lands and extending patterns, allowing easy flow of underfill and preventing voids and air traps, combined with a method of underfill dispensing that utilizes capillary action to fill the gap between the semiconductor die and the circuit board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If underfill is dispensed between the circuit board and semiconductor die, then the semiconductor die is fixed to the circuit board, but voids and air traps form in the underfill causing device failure at high temperatures
Solution Approach 1:
The patent divides the protective layer into multiple segments by forming trenches that expose conductive lands and extending patterns. This segmentation allows underfill to flow through the trenches and fill the gap between the semiconductor die and circuit board more effectively, preventing voids and air traps from forming in the underfill.
Solution Approach 2:
The trenches in the protective layer serve as intermediary pathways that facilitate the flow of underfill material. These trenches act as channels that guide the underfill to the mounting region, ensuring complete filling and eliminating trapped air pockets that would otherwise compromise device reliability.
2Ease of manufacture
If the protective layer completely covers the conductive lands, then the conductive structures are protected, but underfill cannot flow properly to fill the gap between semiconductor die and circuit board
Solution Approach 1:
The patent applies local quality by selectively removing the protective layer only in specific regions where trenches are formed to expose conductive lands and extending patterns. The protective layer remains intact in other areas to provide protection, while the localized trenches enable proper underfill flow and filling without compromising overall protective coverage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces voids and air traps in the underfill, enhancing the mechanical and thermal stability of semiconductor devices by ensuring complete filling and secure bonding between the semiconductor die and the circuit board.
Implementation Method 1
a method of underfill dispensing that utilizes capillary action to fill the gap between the semiconductor die and the circuit board
Data Source
AI summary
A circuit board has an insulative layer including a first surface and a second surface opposite to the first surface. A plurality of electrically conductive patterns is formed on the first surface of the insulative layer. Conductive lands are formed in a die mounting region of the first surface of the insulative layer and electrically connected to one of the plurality of conductive patterns on the first surface. An extending pattern extends from the conductive lands to outside of the mounting region. A protective layer covers the first surface of the insulative layer and the electrically conductive patterns. A trench is formed in the protective layer to expose the conductive lands and the extending patterns.