Optical Coupling Package Structure to Suppress Resin Wetting
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Solution Overview
Problem
Existing optical coupling devices face challenges in increasing the reliability of light-emitting elements protected by resin, particularly due to issues with encapsulation resin wetting and spreading, which can lead to copper elution, impurities, and clamping defects during wire bonding.
Innovation Solution
The optical coupling device employs a multi-layer resin structure with a first resin part on the leadframe that forms a concave shape to suppress encapsulation resin wetting and spreading, using a light-transmissive resin for the first and second parts to protect the light-emitting element and a light-shielding resin for the fourth part to shield external light, thereby enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If encapsulation resin is used to protect the light-emitting element, then the light-emitting element is protected, but the resin may wet and spread causing copper elution, impurities, and clamping defects
Solution Approach 1:
The encapsulation structure is divided into multiple segments: a first resin layer (concave meniscus layer) and a second resin layer (dome-shaped encapsulation layer). The first resin layer is segmented into a light-shielding portion and a light-transmissive portion, creating functional zones that prevent resin wetting while maintaining light transmission where needed.
Solution Approach 2:
The first resin layer acts as an intermediary barrier between the leadframe and the second resin layer. This intermediate layer prevents direct contact and wetting between the encapsulation resin and the leadframe, thereby preventing copper elution and harmful interactions while still providing protective coverage.
2Object-affected harmful factors
If a light-shielding resin is used, then external light is blocked, but light transmission from the light-emitting element may be hindered
Solution Approach 1:
The first resin layer exhibits local quality differentiation with distinct optical properties in different regions. The light-shielding portion (first region) blocks external light from reaching the light-receiving element, while the light-transmissive portion (second region) allows light from the light-emitting element to pass through to the light-receiving element, optimizing both protection and functionality in different spatial zones.
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
The solution effectively prevents resin wetting and spreading without stamping, ensuring reliable protection of the light-emitting element and improving the overall package reliability by adjusting thermal expansion coefficients and using specific resins to enhance adhesion and light transmission.
Implementation Method 1
The second resin is located between the light-emitter and the light-receiver in the first direction and is light-transmissive
Implementation Method 2
The fourth resin houses the light-emitter, the light-receiver, the first resin, the second resin, and the third resin and is light-shielding
Data Source
AI summary
An optical coupling device includes a leadframe, a light-emitter, a light-receiver, and first to fourth resins. The light-emitter is located on the leadframe. The first resin is located on the leadframe. The first resin includes first and second portions. The first portion surrounds the light-emitter. The second portion is positioned between the first portion and the light-emitter. A first thickness of the first portion is greater than a second thickness of the second portion. The second resin is located between the light-emitter and the light-receiver in the first direction and is light-transmissive. The third resin is located between the second resin and the light-receiver and is light-transmissive. The fourth resin houses the light-emitter, the light-receiver, and the first to third resins and is light-shielding.