Optical Sensor Cap Slot Prevents Adhesive Bleeding
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Solution Overview
Problem
Proximity sensor packages face issues with adhesive material bleeding during staging and curing, which can block air vents and obscure light-emitting or light-receiving openings, affecting the functionality of optical sensors.
Innovation Solution
The optical sensor package design incorporates a cap with a slot or recessed structure in its inner wall to accommodate adhesive material, preventing it from bleeding up the sidewalls and ensuring unobstructed airflow and light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive material is applied to secure the cap to the substrate and sensor die, then the cap is firmly attached, but the adhesive material bleeds up the sidewalls and blocks air vents and light openings
Solution Approach 1:
The inner wall is segmented by introducing a groove that divides the adhesive application area from the sidewall area. This segmentation prevents the adhesive from flowing continuously up the sidewall while maintaining attachment strength at the base.
Solution Approach 2:
The groove acts as an intermediary structure between the adhesive material and the sidewall. It provides a controlled path for adhesive placement while physically blocking the adhesive from migrating up the sidewall to block vents and openings.
2Reliability
If adhesive material is applied generously to ensure proper bonding, then reliable attachment is achieved, but the adhesive obscures light-emitting and light-receiving openings
Solution Approach 1:
The groove segments the adhesive containment area, allowing generous adhesive application for reliable bonding while confining it to a specific zone that does not overlap with light openings, thus preserving light transmission.
Solution Approach 2:
The groove creates a localized adhesive containment zone with different properties from the rest of the cap interior. Adhesive is concentrated in this specific local area, ensuring bonding reliability without affecting light transmission in other areas.
3Quantity of substance
If adhesive material flows freely during staging and curing, then complete coverage is achieved, but air vents become blocked
Solution Approach 1:
The groove segments the adhesive flow path, allowing complete coverage within the contained area while preventing overflow into the air vent regions. This ensures adequate adhesive quantity for bonding without blockage of ventilation pathways.
Solution Approach 2:
The groove serves as an intermediary barrier that manages adhesive flow during staging and curing. It permits complete adhesive coverage in the bonding zone while acting as a physical stop that prevents adhesive from reaching and blocking air vents.
Data Source
AI summary
One or more embodiments are directed to system in package (SiP) for optical devices, such as proximity sensing or optical ranging devices. One embodiment is directed to an optical sensor package that includes a substrate, a sensor die coupled to the substrate, a light-emitting device coupled to the substrate, and a cap. The cap is positioned around side surfaces of the sensor die and covers at least a portion of the substrate. The cap includes first and second sidewalls, an inner wall having first and second side surfaces and a mounting surface, and a cover in contact with the first and second sidewalls and the inner wall. The first and second side surfaces are transverse to the mounting surface, and the inner wall includes an opening extending into the inner wall from the mounting surface. A first adhesive material is provided on the sensor die and at least partially within the opening, and secures the inner wall to the sensor die.