Fan-Out Wafer-Level Packaging With UV Protective Layer for Solder Stability
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Solution Overview
Problem
High-temperature processes in fan-out wafer-level packaging can cause Tin-Silver solder in passive components to melt, leading to electrical shorts or delamination between the epoxy molding compound and capacitors.
Innovation Solution
A method involving a rewiring layer, UV-curable adhesive protective layer, and molding layer is used, where the UV-curable adhesive is solidified using UV light and further heat-treated, preventing solder melting and ensuring reliable encapsulation of electrical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature processes (pre-pressing at 240°C, reflow at 260°C) are used in fan-out wafer-level packaging, then the encapsulation and bonding processes can be completed, but the Tin-Silver solder in passive components melts and flows causing electrical shorts or delamination
Solution Approach 1:
A protective layer is formed on the solder joints of passive components before the high-temperature encapsulation process. This protective layer prevents solder from melting and flowing during subsequent high-temperature processing, eliminating the need to avoid high-temperature processes while still protecting the solder joints.
Solution Approach 2:
The protective layer acts as an intermediary substance between the solder joints and the high-temperature environment. It has properties that allow it to withstand high temperatures while protecting the underlying solder, enabling the encapsulation process to proceed at high temperatures without causing solder damage.
2Reliability
If conventional epoxy molding compound encapsulation is used, then the chip and components are encapsulated, but electrical shorts and delamination occur due to solder melting
Solution Approach 1:
The protective layer is applied to solder joints before encapsulation, preventing solder from melting and causing electrical shorts or delamination during the high-temperature encapsulation process. This preliminary protection measure eliminates the harmful effects while maintaining the benefits of high-temperature encapsulation.
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 protective layer effectively seals electrical components, preventing solder spillage and electrical shorts, enhancing the reliability of the fan-out wafer-level packaging structure by maintaining the integrity of the adhesive and preventing delamination.
Implementation Method 1
dispensing UV-curable adhesive on surfaces of the electrical component, and irradiate the UV-curable adhesive with UV light so that the UV-curable adhesive solidifies
Implementation Method 2
heat generated during formation of the molding layer further heats and solidifies the protective layer
Data Source
AI summary
A fan-out wafer-level packaging structure and a method for manufacturing it are disclosed. The structure includes: a rewiring layer, a chip, an electrical component, a protective layer made of UV-curable adhesive, a molding layer, and a solder ball. The protective layer is disposed on surfaces of the electrical component, sealing the electrical component, and ensuring its safe operation and reliability, mitigating risks of melting and spillage of solder in the electrical component, and preventing electrical shorts and delamination between molding layers and the electrical component. The protective layer is formed by UV-curing or UV/thermal-dual-curing, to prevent loss of upper portions of the adhesive resulted from the upper portions flowing downward after dispensing. A dual-curing process can further solidify the protective layer, enabling the protective layer to better seal and protect the electrical component.