Semiconductor Package Stiffener Design for Warping Prevention
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Solution Overview
Problem
Thin type semiconductor packages with different thermal expansion coefficients of conductive and insulating materials warp during thermal processes, causing substrate misalignment and solder ball joint issues, and existing stiffeners require extra adhesives and obstructive heights to prevent warping.
Innovation Solution
A semiconductor package design featuring a stiffener with sufficient mechanical robustness, made of metal or solid materials, that can be directly mounted on the carrier using the encapsulant's attaching force without additional adhesives, allowing for a smaller height and volume, and optionally incorporating grooves for increased attachment area, thus preventing substrate warping during thermal processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a stiffener is used to prevent substrate warping during thermal processes, then mechanical robustness is improved, but additional adhesives and increased height are required
Solution Approach 1:
The stiffener is integrated with the carrier such that the encapsulant serves dual functions: both sealing the chip and providing attaching force to secure the stiffener. This eliminates the need for separate adhesives and reduces processing steps while maintaining mechanical robustness and preventing substrate warping during thermal processes.
2Stability of the object's composition
If a stiffener with sufficient mechanical robustness is used to prevent warping, then substrate stability is improved, but the stiffener height and volume increase
Solution Approach 1:
The stiffener is positioned specifically around the periphery of the chip where it is most needed for preventing warping, rather than covering the entire chip area. This localized placement maintains substrate stability while minimizing the overall volume and height of the stiffener structure.
3Strength
If a stiffener is attached by extra adhesive, then attachment strength is improved, but processing complexity increases
Solution Approach 1:
The encapsulant is designed to perform multiple functions simultaneously: it seals the chip to protect it from environmental factors and also provides the attaching force to secure the stiffener to the carrier. This multi-functionality eliminates the need for separate adhesives and simplifies the manufacturing process while maintaining strong attachment.
4Reliability
If stiffener height is increased to prevent wire damage, then chip protection is improved, but layout flexibility is reduced
Solution Approach 1:
The stiffener is positioned around the periphery of the chip rather than covering the entire chip area. This localized placement provides adequate protection for bonding wires at the edges while leaving the central chip area exposed, thereby maintaining layout flexibility for component placement and electrical connections.
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 prevents substrate warping during thermal processes, reduces processing steps by eliminating the need for extra adhesives, and allows for a more economical and easily manufacturable package with improved layout flexibility.
Implementation Method 1
the stiffener can be directly mounted on the carrier by the attaching force of an encapsulant
Implementation Method 2
Due to the different CTE's of various conductive and insulating materials used in the BGA package after the BGA package is packaged, the BGA package having the thin type substrate may be warped seriously during subsequent thermal processes
Data Source
AI summary
A semiconductor package includes a carrier, a chip, a stiffener and an encapsulant. The chip is disposed on the carrier. The stiffener is disposed around the chip, directly contacts the carrier, and is mounted on the carrier. The encapsulant is adapted to seal the chip and the stiffener.