Sensor Package Structure With Avoidance Slot to Prevent Sheet Cracking
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Solution Overview
Problem
Conventional sensor package structures face issues with cracking of the light-permeable layer due to stress concentration from the encapsulant on its surrounding lateral surface during the solidification process.
Innovation Solution
A manufacturing method involving formation of grooves on a light-permeable board, slicing to create light-permeable sheets with avoidance slots, and a sacrificial layer to form a sensor package structure with a filler settling boundary that avoids stress concentration on the light-permeable sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the encapsulant is formed by solidifying a liquid compound covering the surrounding lateral surface of the light-permeable layer, then the encapsulant provides protection and structural support, but the surrounding lateral surface of the light-permeable layer cracks due to stress concentration from the encapsulant
Solution Approach 1:
The encapsulant is divided into two distinct segments: a first segment that contacts the light-permeable sheet and a second segment that is spaced apart from it. This segmentation prevents stress concentration on the light-permeable layer while maintaining the encapsulant's protective and structural functions. The gap between segments eliminates the direct stress transmission that causes cracking.
Solution Approach 2:
A sacrificial layer is introduced as an intermediary element between the light-permeable sheet and the encapsulant. This layer is positioned in the gap between the light-permeable sheet and the encapsulant, acting as a buffer that prevents direct contact and stress concentration. The sacrificial layer can be removed after bonding, leaving a protective gap that maintains both structural support and layer integrity.
2Volume of moving object
If the encapsulant is positioned close to the light-permeable sheet for compact design, then space efficiency is improved, but stress concentration causes cracking of the light-permeable layer
Solution Approach 1:
The encapsulant is segmented into first and second segments with a controlled gap between them. This allows the package to maintain compact dimensions while the gap prevents stress concentration on the light-permeable layer. The segmented structure achieves both compactness and reliability by decoupling the protective function from the stress-transmitting function.
Solution Approach 2:
The sacrificial layer serves as a mediator that enables close positioning of the encapsulant to the light-permeable sheet while preventing direct stress contact. After the bonding process, the sacrificial layer is removed, creating a permanent gap that maintains both compact packaging and prevents cracking under operational stresses.
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
Prevents cracking of the light-permeable sheet by positioning the stress concentration part of the encapsulant away from the sheet, enhancing structural integrity.
Implementation Method 1
solidifying a liquid compound covering a surrounding lateral surface of a light-permeable layer
Implementation Method 2
The fillers are precipitated in the first segment
Data Source
AI summary
A sensor package structure and a manufacturing method thereof are provided. The sensor package structure includes a substrate, a sensor chip mounted on the substrate, a ring-shaped supporting layer disposed on the sensor chip, a light-permeable sheet disposed on the ring-shaped supporting layer, and an encapsulant formed on the substrate. The top portion of the light-permeable sheet has an avoidance slot formed on an outer edge thereof. The encapsulant is formed by a solidified liquid compound and is not located in the avoidance slot. The encapsulant includes an adhesive and a plurality of fillers mixed in the adhesive. The encapsulant has a filler settling boundary through the precipitation of the fillers. The inner edge of the filler settling boundary is not in contact with the light-permeable sheet and surrounds at an outer side of the avoidance slot.