Semiconductor Package Backside Metal Layers for Warpage Control
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Solution Overview
Problem
Conventional chip scale packages face issues with warpage and cracking due to the lack of rigid support after separation from the carrier board, affecting the reliability of subsequent processes and product yield.
Innovation Solution
A semiconductor package and fabrication method that includes forming first and second metal layers on the second surface of the encapsulant to provide a rigid support, using electroless plating or sputtering for the first layer and electroplating for the second layer, along with a built-up structure featuring a dielectric layer, wiring layer, and conductive vias, and an insulating protection layer for heat dissipation and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the carrier board is completely removed after encapsulation, then the chip and encapsulant can be fully separated for independent wiring processing, but the package structure loses rigid support causing warpage and cracking
Solution Approach 1:
A rigid support layer is introduced as an intermediary element between the chip/encapsulant assembly and the external environment. This support layer maintains structural stability during wiring operations on the backside of the package, preventing warpage and cracking while allowing complete separation from the carrier board for independent processing.
Solution Approach 2:
The rigid support layer is formed on the backside of the encapsulant before the carrier board is removed. This preliminary structural reinforcement ensures that the package maintains its shape and integrity during subsequent wiring operations, preventing the warpage and cracking that would occur if the carrier board were removed without providing alternative support.
2Adaptability or versatility
If wiring process is performed on the backside of the package, then more electrode connections can be achieved, but warpage occurs on the front side reducing process reliability
Solution Approach 1:
The rigid support layer acts as a mediator that balances the structural loads during backside wiring operations. By providing distributed support across the backside of the encapsulant, it prevents the front side from warping while allowing versatile electrode connections to be made on the backside.
Solution Approach 2:
The rigid support layer functions as a counterweight to the wiring structures being added on the backside. This counterbalancing support prevents the front side of the package from warping under the asymmetric loading conditions created during backside wiring processes, maintaining manufacturing precision.
3Temperature
If multiple metal layers are formed on the encapsulant surface, then heat dissipation capability is improved, but the fabrication process complexity increases
Solution Approach 1:
Multiple metal layers with different properties are formed on the encapsulant surface to create a composite thermal management structure. The first metal layer provides initial heat dissipation and adhesion, while the second metal layer enhances thermal conductivity and provides additional heat dissipation pathways, achieving superior thermal performance through material composition rather than单一材料.
Solution Approach 2:
The multi-layer metal structure serves multiple functions simultaneously: the first metal layer provides adhesion and initial heat dissipation, while the second metal layer enhances thermal conductivity and provides additional heat dissipation surfaces. This multi-functional design improves heat dissipation efficiency without requiring separate systems for each function.
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 warpage and cracking, enhances the reliability of subsequent processes, and improves product yield by providing a rigid support and facilitating heat dissipation in the semiconductor package.
Implementation Method 1
using electroless plating or sputtering for the first layer
Implementation Method 2
using electroless plating or sputtering for the first layer
Implementation Method 3
using electroplating for the second layer
Data Source
AI summary
A semiconductor package includes: a chip having an active surface with a plurality of electrode pads and an inactive surface opposite to the active surface; an encapsulant encapsulating the chip and having opposite first and second surfaces, the first surface being flush with the active surface of the chip; and first and second metal layers formed on the second surface of the encapsulant, thereby providing a rigid support to the overall structure to prevent warpage and facilitating heat dissipation of the overall structure.