Chip Package Substrate Embedded in Molding Material to Reduce Warpage
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Solution Overview
Problem
The existing chip packaging methods face challenges in reducing package thickness while maintaining structural integrity, leading to warpage issues due to the differential shrinkage rates of injection molding materials and dies, which affects the attachment and reliability of fingerprint chips in thinner terminals.
Innovation Solution
A chip package structure is developed where a solder joint is placed on one surface of the die, and the remaining surfaces are wrapped with injection molding material, with at least one pair of opposite sides of the package substrate embedded in the material to create a stable buckle structure, increasing adhesion and reducing warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the package thickness is reduced to meet terminal requirements, then the terminal becomes lighter and thinner, but warpage occurs due to differential shrinkage between injection molding material and die
Solution Approach 1:
The patent applies asymmetry by selectively embedding only one pair of opposite sides of the package substrate into the injection molding material, rather than embedding all sides or none. This asymmetric embedding creates an anchor effect that counteracts the differential shrinkage forces without requiring complete encapsulation, thus reducing warpage while maintaining thin profile.
Solution Approach 2:
The patent transitions from a two-dimensional surface attachment problem to a three-dimensional embedded structure. By embedding the package substrate sides into the injection molding material volume rather than merely attaching surfaces, the solution creates internal anchoring that resists warpage forces more effectively while maintaining overall thinness.
2Length of moving object
If injection molding material is not molded on the upper surface of the die to reduce package thickness, then the package becomes thinner, but the die and injection molding material shrink at different rates causing warpage
Solution Approach 1:
The patent uses asymmetric embedding where only one pair of opposite sides of the package substrate is embedded in the injection molding material. This creates an internal anchor that compensates for the lack of material on the upper surface, maintaining flatness despite the thin profile and differential shrinkage.
Solution Approach 2:
The embedded package substrate sides act as a preliminary counteracting structure that resists the warpage forces before they fully develop during the shrinkage process. The embedded portions create internal stresses that balance the differential shrinkage between the die and injection molding material.
3Reliability
If the contact area between package substrate and injection molding material is increased, then adhesion and stability are improved, but the complexity of the packaging structure increases
Solution Approach 1:
The patent achieves high adhesion strength by embedding only one pair of opposite sides of the package substrate, creating concentrated contact areas that provide sufficient anchoring without requiring complete encapsulation. This asymmetric approach maximizes adhesion where needed while minimizing overall structural complexity.
Solution Approach 2:
The patent applies partial embedding rather than complete encapsulation. By embedding only the necessary one pair of opposite sides, the solution achieves sufficient adhesion strength to prevent warpage and detachment without the excessive complexity of full encapsulation structures.
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 solution effectively alleviates warpage and enhances the stability and reliability of the chip package by increasing the contact area between the package substrate and the injection molding material, ensuring a stronger and more reliable attachment of the die within the package.
Implementation Method 1
when the fingerprint chip is being packaged, the die 11 and the injection molding material 12 shrink at a high temperature or in another condition, and a shrinkage degree of the injection molding material 12 with relatively low strength is greater than a shrinkage degree of the die 11
Data Source
AI summary
A chip package structure and a chip package method, the chip package structure including a die and a package substrate disposed around the die. A solder joint is disposed on a first surface of the die. Remaining surfaces of the die other than a second surface are wrapped by an injection molding material. At least one pair of opposite sides of the package substrate is embedded in the injection molding material. A contact area between the pair of opposite sides and the injection molding material accounts for more than half of a surface area of the pair of opposite sides. The second surface is a surface that is of the die and that is opposite to the first surface.