Sensor Package Aperture Layout to Prevent Resin Intrusion
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Solution Overview
Problem
Conventional sensor packages face issues with degradation in sensor unit quality due to resin intrusion and cracking during the molding process, affecting detection accuracy and functionality.
Innovation Solution
A sensor package design featuring a chip with a flat part surrounding the exposed sensor unit, a substrate, and a molded resin portion with an aperture, where the mold edge is aligned with the flat part to prevent resin intrusion, reducing the risk of cracks and maintaining sensor integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the molded resin portion covers the chip surface during the molding process, then the sensor unit is protected from external contamination, but resin may intrude onto the sensor unit causing quality degradation
Solution Approach 1:
The chip surface is segmented into an exposed portion (where the sensor unit is located) and a non-exposed portion. The molded resin portion selectively covers only the non-exposed portion, leaving the sensor unit exposed and preventing resin intrusion while still providing protection for other areas.
Solution Approach 2:
Different regions of the chip surface are treated differently: the exposed portion remains uncovered to prevent resin contamination of the sensor unit, while the non-exposed portion is covered by molded resin for protection. This local differentiation resolves the contradiction between protection and contamination prevention.
2Manufacturing precision
If the mold applies pressure to form the molded resin portion, then the resin properly fills and covers the chip, but cracks may occur in the sensor unit affecting detection accuracy
Solution Approach 1:
The molding process is segmented such that pressure is applied only to the non-exposed portion of the chip surface. The exposed portion containing the sensor unit is excluded from the high-pressure molding zone, preventing crack formation while still achieving proper resin coverage in protected areas.
3Volume of moving object
If the aperture is positioned close to the sensor unit for compact design, then the package size is reduced, but resin intrusion risk increases during molding
Solution Approach 1:
The aperture region is treated as a local exception where the chip surface is exposed rather than covered by molded resin. This localized exposure strategy allows compact aperture positioning near the sensor unit while preventing resin intrusion through the aperture edges, as resin is not applied in the exposed zone.
Data Source
AI summary
A sensor package includes: a chip including a surface on which the exposed portion of a sensor unit is provided; a substrate including a surface on which the chip is mounted; and a molded resin portion covering the surface of the substrate and the surface of the chip excluding the exposed portion. The molded resin portion includes an aperture positioned above the exposed portion. The chip includes a flat part positioned outside of the exposed portion on the surface of the chip. The edge of the aperture on the surface side of the chip is formed along the flat part.