Semiconductor Package Land Structure With Mold-Locking Reliability
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Solution Overview
Problem
MLF type semiconductor packages face reliability issues due to lands dislodging during manufacturing or assembly, which reduces their functionality and reliability.
Innovation Solution
A land structure is designed with a larger upper portion relative to a smaller lower portion, isolated by an insulating layer, and secured with a locking mechanism to prevent detachment, using a method that includes selective etching and resin filling to create cavities and plating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional MLF type semiconductor package structure is used, then the package size can be reduced, but the lands become dislodged during manufacturing or assembly, reducing reliability
Solution Approach 1:
The land structure is divided into an upper land portion and a lower land portion separated by an insulating layer, with the lower land portion extending into the mold compound to form a locking structure. This segmentation allows the land to be mechanically anchored in the mold compound while maintaining electrical functionality at the upper portion, preventing dislodgement during assembly.
Solution Approach 2:
The land structure extends in the vertical dimension by having the lower land portion protrude downward into the mold compound below the adhesion pad level. This vertical extension creates a locking mechanism that anchors the land structure within the mold compound, preventing horizontal dislodgement while maintaining the compact horizontal footprint of the package.
2Reliability
If the land structure is made larger to improve connection stability, then reliability improves, but the package size increases
Solution Approach 1:
By segmenting the land structure into upper and lower portions separated by an insulating layer, the design allows the lower portion to extend vertically into the mold compound for mechanical anchoring without increasing the horizontal footprint. This enables connection stability through vertical locking while maintaining compact package dimensions.
Solution Approach 2:
The solution transitions from horizontal land expansion to vertical extension by having the lower land portion protrude downward into the mold compound. This dimensional change provides mechanical locking and connection stability without increasing the horizontal package footprint, thus maintaining small package size while improving reliability.
3Reliability
If a locking mechanism is added to prevent land detachment, then reliability improves, but device complexity increases
Solution Approach 1:
The locking mechanism is merged with the land structure itself rather than being a separate component. The lower land portion is integrally formed with the lead frame and extends into the mold compound, combining the electrical connection function with the mechanical locking function in a single integrated structure, thus avoiding additional device complexity.
Solution Approach 2:
The land structure serves dual functions: the upper land portion provides electrical connection while the lower land portion automatically locks into the mold compound during the molding process. The structure self-anchors itself without requiring separate locking mechanisms or additional assembly steps, maintaining simplicity while improving reliability.
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 improved land structure enhances the reliability and functionality of semiconductor packages by preventing lands from detaching, ensuring stable electrical connections and improved assembly processes.
Implementation Method 1
The land structure and the adhesion pad are physically isolated from each other using, for example, an insulating layer
Implementation Method 2
a method that includes selective etching and resin filling to create cavities
Implementation Method 3
a method that includes selective etching and resin filling to create cavities
Implementation Method 4
secured with a locking mechanism to prevent detachment, using a method that includes selective etching and resin filling to create cavities and plating layers
Data Source
AI summary
A semiconductor package structure includes a substrate comprising a land structure. The land structure includes a first land section having a first height in a cross-sectional view and a second land section having a second height in the cross-sectional view that is different than the first height. A mold encapsulant is disposed adjacent a lateral portion of the first land section and is disposed below a bottom portion of the second land section. A semiconductor die is attached to the substrate, and includes a first major surface, a second major surface opposing the first major surface, and an outer perimeter. The semiconductor die further includes a bonding structure disposed adjacent the first major surface, which is coupled to the second land section such that the first land section is disposed outside the perimeter of the semiconductor die A mold member encapsulates at least portions of the semiconductor die.