Exposed-Die Mold Package with Dams for Sensor Encapsulation
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Solution Overview
Problem
Existing sensor packaging methods, such as metal can packages and mold packages, face challenges in providing a low-cost, high-volume solution for sensors that require direct access to the environment while minimizing the packaging footprint and avoiding mold material obstruction of the sensing area.
Innovation Solution
A method for forming an exposed-die mold package involves depositing dams to create exclusionary zones around sensor areas, followed by encapsulating the sensors with mold material, ensuring the sensing areas remain unobstructed and protected from environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mold packages are used to encapsulate sensors, then cost is reduced and high volume production is enabled, but the sensing area becomes obstructed by mold material
Solution Approach 1:
The packaging structure is segmented into multiple regions using dams: an exposed region for sensing, a sealed region for protection, and a transition region. This segmentation allows mold material to be deposited only in designated areas, preventing obstruction of the sensing area while maintaining the benefits of mold packaging.
Solution Approach 2:
A dam structure acts as an intermediary element between the sensing area and the mold material. The dam creates a physical barrier that directs mold material away from the sensing area, enabling both mold packaging advantages and sensing area clearance to be achieved simultaneously.
2Strength
If metal can packages are used to protect sensor components, then mechanical impact protection is improved, but packaging footprint and height increase
Solution Approach 1:
The patent uses a thin mold package structure instead of a bulky metal can. The mold material forms a flexible protective shell that provides adequate protection while occupying minimal space, thereby reducing the packaging footprint compared to traditional metal can packages.
3Reliability
If metal can packages are used to protect bond wires, then wire shorting is prevented, but package height increases
Solution Approach 1:
Instead of protecting bond wires by increasing height (vertical dimension) with a metal can, the patent uses dams to create lateral (horizontal dimension) separation and containment. The dams confine mold material to specific regions, providing wire protection through horizontal segmentation rather than vertical extension.
Data Source
AI summary
A method of encapsulating a sensor device includes providing at least one sensor device that has a sensor portion on a substrate. An exclusionary zone is formed above an upper surface of the sensor portion. An outer boundary is formed on or about the sensor device with the outer boundary encircling the exclusionary zone. A mold material is deposited into a volume defined in part by the sensor device, the exclusionary zone, and the outer boundary to encapsulate portions of the sensor device. The exclusionary zone in one embodiment is an inner boundary that is formed on the sensor portion. The inner boundary encircles a portion of the upper surface of the sensor portion. The exclusionary zone in another embodiment is a selectively removable material deposited on the upper surface of the sensor portion. The selectively removable material occupies a space above a portion of the upper surface.