Encapsulating Sheet Offset for LED Void Suppression
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Solution Overview
Problem
The existing methods for encapsulating semiconductor elements, such as LEDs, often result in voids due to bubbles in the resin, which reduces the reliability of the semiconductor device by causing uneven light emission and luminous efficiency between multiple LEDs.
Innovation Solution
An encapsulating sheet-covered semiconductor element is designed where the encapsulating sheet is positioned such that its exposed surface is not in contact with the same plane as the semiconductor element, reducing void formation and enhancing reliability, and a method involving a support sheet, semiconductor element placement, and encapsulating sheet application under normal pressure to simplify the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the encapsulating sheet is applied onto the pressure-sensitive adhesive sheet including the chip, then the chip is covered and protected, but a bubble is easily involved and a void is generated in the resin, reducing reliability
Solution Approach 1:
The patent positions the exposed surface of the encapsulating sheet at a different height dimension relative to the semiconductor element surface. Specifically, the exposed surface is positioned toward the other side (opposite side) with respect to the one surface of the semiconductor element, creating a stepped or offset configuration that prevents bubble entrapment during the encapsulation process.
Solution Approach 2:
The patent introduces a support sheet as an intermediary component between the semiconductor element and the encapsulating sheet. The support sheet provides a stable base for mounting the semiconductor element and facilitates the application process, allowing the encapsulating sheet to be positioned correctly without direct contact that would cause bubble formation.
2Reliability
If resin is applied onto the chip to fabricate encapsulated structure, then the chip is protected, but bubbles are easily trapped in the resin, generating voids
Solution Approach 1:
The patent employs a dimensional offset where the exposed surface of the encapsulating sheet is positioned at a different height level than the semiconductor element surface. This vertical displacement creates a configuration where the encapsulating sheet does not fully contact the semiconductor element surface, preventing bubble entrapment during resin application while maintaining protective coverage.
Solution Approach 2:
The patent performs preliminary mounting of the semiconductor element onto a support sheet before applying the encapsulating sheet. This preliminary action establishes a stable base and correct positioning, allowing the encapsulating sheet to be applied without causing bubble formation or void generation in the resin.
3Reliability
If multiple LEDs are mounted on a board with encapsulating layer, then the LEDs are protected and function, but unevenness in emission wavelength and luminous efficiency is generated between LEDs
Solution Approach 1:
The patent applies the offset positioning principle to multiple LEDs mounted on a board. By positioning the exposed surfaces of encapsulating sheets at different height dimensions relative to each LED, the invention ensures uniform encapsulation conditions across all LEDs, eliminating variations in emission wavelength and luminous efficiency that would otherwise occur due to inconsistent resin application or bubble formation.
Data Source
AI summary
An encapsulating sheet-covered semiconductor element includes a semiconductor element having one surface in contact with a board and the other surface disposed at the other side of the one surface and an encapsulating sheet covering at least the other surface of the semiconductor element. The encapsulating sheet includes an exposed surface that is, when projected from one side toward the other side, not included in the one surface of the semiconductor element and exposed from the one surface and the exposed surface has the other side portion that is positioned toward the other side with respect to the one surface of the semiconductor element.