Grooved Substrate for Semiconductor Package Void Prevention
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Solution Overview
Problem
The challenge in packaging semiconductor devices is the formation of voids in the mold compound due to the difficulty in filling small channels between the semiconductor device and the substrate, which can lead to reliability failures, especially as package sizes decrease and filler particle sizes increase.
Innovation Solution
The method involves laser ablating grooves of specific widths and depths in the substrate between landing pads to create larger channels that facilitate the flow and filling of mold compound, preventing voids by forming channels with wider dimensions than the filler particles, thereby ensuring complete encapsulation without voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If package size is decreased, then device miniaturization is achieved, but channel size between semiconductor device and substrate becomes too small to fill properly with mold compound
Solution Approach 1:
The substrate surface is segmented by creating grooves that divide the mounting surface into separate regions. These grooves create larger effective channel dimensions between the semiconductor device and substrate, allowing mold compound to flow and fill properly even when the overall package size is reduced. The grooves segment the space to ensure adequate flow paths for encapsulation.
2Quantity of substance
If filler particle size in mold compound is increased, then manufacturing cost is reduced, but void formation in small channels increases
Solution Approach 1:
The groove dimensions (width and depth) are specifically designed to change the channel parameters, making the channel width at least 1.5 times the diameter of the largest filler particles. This parameter adjustment ensures that larger, more cost-effective filler particles can be used while preventing void formation during mold compound filling.
3Manufacturing precision
If groove dimensions are increased to facilitate mold compound flow, then channel filling improves, but substrate area available for landing pads decreases
Solution Approach 1:
The grooves are strategically positioned in specific regions of the substrate where they provide flow channels without interfering with landing pad functionality. The groove width is controlled to be sufficient for mold compound flow while maintaining adequate substrate area for electrical connections. This localized approach ensures both filling quality and electrical performance.
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
This approach effectively prevents void formation in the mold compound, enhancing the reliability of packaged semiconductor devices by ensuring complete encapsulation and reducing the risk of failure, while allowing for smaller package sizes and improved electrical connections.
Implementation Method 1
laser ablating a first groove with a first width and a first depth into a mounting surface of a substrate between landing pads
Data Source
AI summary
In a described example, a method for making a packaged semiconductor device includes laser ablating a first groove with a first width and a first depth into a mounting surface of a substrate between landing pads. A first pillar bump on an active surface of a semiconductor device is bonded to a first landing pad; and a second pillar bump on the semiconductor device is bonded to a second landing pad. A channel forms with the active surface of the semiconductor device forming a first wall of the channel, the first pillar bump forms a second wall of the channel, the second pillar bump forming a third wall of the channel, and a surface of the first groove forms a fourth wall of the channel. The channel is filled with mold compound and at least a portion of the substrate and the semiconductor device are covered with mold compound.