Die Pad Recess Structure to Prevent Resin Flash Delamination
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Solution Overview
Problem
Current semiconductor manufacturing processes face issues with resin leaks or flashes at the bottom surface of the die pad, leading to inadequate plating and potential short circuits, while conventional de-flashing processes can cause delamination between the leadframe and the encapsulation.
Innovation Solution
A method involving the application of laser beam energy to form a recessed portion at the bottom surface of the die pad, which is then filled with electrically insulating molding compound, enhancing adhesion and preventing resin leaks. Additionally, the adhesion promoter layer is removed via laser ablation at the recessed portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional de-flashing processes (dry de-flashing via laser ablation or chemical de-flashing) are used to remove resin flashes, then resin flashes are removed, but delamination between the metallic material of the leadframe and the electrically insulating encapsulation is promoted
Solution Approach 1:
A protrusion is formed on the bottom surface of the die pad before the molding process. This protrusion serves as a mechanical anchor that prevents resin flashes from detaching during subsequent de-flashing processes, thereby maintaining adhesion between the leadframe and encapsulation while still allowing effective removal of resin flashes
Solution Approach 2:
The bottom surface of the die pad is modified locally by forming a protrusion at a specific location. This localized structural change provides targeted reinforcement against resin flash detachment without affecting the overall adhesion properties of the entire leadframe-encapsulation interface
2Reliability
If resin flashes are not removed, then adhesion is maintained, but inadequate plating occurs and short circuits may result
Solution Approach 1:
The protrusion is formed on the die pad bottom surface before molding, creating a structural feature that controls resin flash behavior during the molding process. This preliminary structural modification ensures that resin flashes remain attached to the die pad, allowing subsequent plating to occur uniformly without creating short circuits
Solution Approach 2:
Instead of viewing resin flashes purely as harmful defects to be removed, the invention utilizes the protrusion to retain these flashes in a controlled manner. The retained resin flashes are then plated with solder material, converting what would be harmful detachable lumps into beneficial plated features that improve electrical connectivity
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 reduces resin leaks, enhances adhesion between the molding compound and the die pad, and prevents delamination, thereby improving the reliability and performance of semiconductor devices.
Implementation Method 1
applying laser beam energy to a second surface of the die pad to form a recessed portion in the die pad
Implementation Method 2
molding an electrically insulating material onto the die pad to form an electrically insulating encapsulation
Data Source
Figure 1~3
Figure 4
Figure 5A~5B
AI summary
An adhesion promoter layer (100) is provided on first and second opposite surfaces of a die pad (12A) in a substrate (12A, 12B). An encapsulation (20) of electrically insulating material is molded onto the substrate (12A, 12B) having a semiconductor die (14) arranged thereon. The semiconductor die is arranged at a die mounting region (120A) of the first surface of the die pad (12A) in the substrate (12A, 12B). Laser beam energy (LB) is applied to the second surface of the die pad (12A) to form in the second surface of the die pad (12A) a recessed peripheral portion (1000) surrounding a central portion opposite the die mounting region (120A) at the first surface. Applying laser beam energy (LB) to form the recessed peripheral portion (1000) of the second surface of the die pad (12A) comprises removing said adhesion promoter layer (100) therefrom. During molding the electrically insulating material (20) covers the recessed peripheral portion (1000) and leakage of the electrically insulating material (20) over the central portion is countered in response to the peripheral portion (1000) of the second surface of the die pad (12A) being recessed.