Saw Street Protective Layer for High-Pressure Encapsulation
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Solution Overview
Problem
In semiconductor devices, particularly in high-frequency applications like RF wireless communications, the encapsulant can migrate to the electrical connector during encapsulation, causing defects. Additionally, the high pressure applied during encapsulation can damage the substrate or SiP/AiP.
Innovation Solution
A protective layer is formed in the saw street of the substrate to limit pressure during encapsulation. This layer is made of conductive material and spans the width of the saw street, acting as a support structure to withstand pressure without damaging the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressure is applied during encapsulation to prevent encapsulant migration, then encapsulant containment is improved, but substrate damage increases
Solution Approach 1:
A protective layer is introduced as an intermediary element between the substrate and the encapsulation process. This layer absorbs and distributes the high pressure applied during encapsulation, preventing direct transmission of stress to the substrate while maintaining effective encapsulant containment. The protective layer acts as a mediator that enables high pressure to be applied without causing substrate damage.
Solution Approach 2:
The protective layer is formed on the substrate surface before the encapsulation process begins. This preliminary action prepares the substrate by creating a protective barrier that will withstand the subsequent high pressure application, preventing substrate damage before it can occur during the encapsulation process.
2Reliability
If high pressure is applied during encapsulation to prevent encapsulant leakage, then encapsulant migration prevention is improved, but defect rate increases
Solution Approach 1:
The protective layer serves as a mediator that enables the application of high pressure during encapsulation without transmitting damaging stress to the substrate. This allows effective prevention of encapsulant migration while avoiding substrate cracks and defects that would otherwise result from the high pressure application.
Solution Approach 2:
The protective layer is applied beforehand to cushion and absorb the high pressure applied during encapsulation. This prior cushioning prevents the pressure from causing substrate damage or defects, allowing the encapsulation process to proceed with sufficient pressure to prevent encapsulant leakage without compromising substrate integrity.
Data Source
AI summary
A semiconductor device has a substrate and a protective layer formed over a saw street of the substrate. The protective layer may extend over a width of the saw street. The protective layer may extend less than a width of the saw street or extend greater than a width of the saw street. An electrical component is disposed over a surface of the substrate. A connector is disposed over the surface of the substrate. An encapsulant is deposited over the electrical component using a chase mold with a lower housing and upper housing. The encapsulant should not migrate to the connector during encapsulation. High pressure is applied to an upper housing of the chase mold to prevent encapsulant migration to the connector. The protective layer protects the substrate from the high pressure during encapsulation. A shielding layer is formed over the encapsulant.