Optoelectronic Package Structure for Wire and Encapsulant Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optoelectronic device packages suffer from wire breakage and encapsulant cracking due to stress and mismatched expansion coefficients, leading to lower yields.
Innovation Solution
A package structure with inclined sidewalls on lead frame components to guide stress and evenly distribute thermal expansion, combined with rounded corners and consistent gap widths to reduce stress concentration and improve bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wires are connected between chip and lead frame in conventional plug-in package, then electrical connection is achieved, but wires are easily pulled causing breakage resulting in dead lamps
Solution Approach 1:
The bonding part of the lead frame is designed with a rounded corner structure instead of sharp corners. This curvature design reduces stress concentration at the corners during soldering processes, preventing wire breakage and improving connection reliability without compromising wire strength
Solution Approach 2:
The lead frame bonding part is designed with specific dimensional parameters including rounded corner radius R1 (0.05-0.15mm) and R2 (0.1-0.3mm), and controlled gap widths (0.1-0.5mm). These parameter optimizations reduce stress concentration and prevent wire breakage during soldering
2Stability of the object's composition
If lead frame and encapsulant are joined together, then structural integrity is achieved, but joint may crack due to different expansion coefficients
Solution Approach 1:
The patent designs the lead frame with rounded corners and controlled gaps that accommodate thermal expansion differences between the lead frame and encapsulant. The rounded corner structure allows for stress distribution during thermal cycling, preventing crack formation at the joint interface
Solution Approach 2:
The lead frame structure is designed with different local features: rounded corners at bonding parts, specific gap widths between leads, and varied dimensions at different locations. These localized structural modifications address stress concentration issues at critical joints without affecting the overall structure
3Productivity
If conventional package structure is used, then manufacturing simplicity is maintained, but defects occur due to stress concentration leading to lower yields
Solution Approach 1:
The lead frame is designed with asymmetric features including different rounded corner radii (R1 and R2) at different locations, and non-uniform gap widths between leads. This asymmetric design optimizes stress distribution throughout the structure, reducing defects and improving manufacturing yield
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
Reduces wire breakage and encapsulant cracking, enhancing yield and enabling multi-chip configurations with individual control of optoelectronic devices for mixing and dimming light.
Implementation Method 1
by virtue of the first bonding part having the first inclined sidewall at the upper end of one side away from the second lead, a direction of stress released from the first bonding part can be guided, so that a relative displacement between the first bonding part and the carrying part can be decreased
Implementation Method 2
due to different expansion coefficients of a lead frame and an encapsulant, a joint between the encapsulant and the lead frame may crack
Data Source
AI summary
A package structure is provided. The package structure includes at least one optoelectronic device, a lead frame, and an encapsulant. The optoelectronic device is disposed on the lead frame. The lead frame includes at least one lead unit that includes a first lead and a second lead. The first lead has a first bonding part and a first pin. The first bonding part has a first inclined sidewall at an upper end of one side away from the second lead. The second lead has a second pin and a carrying part, of which an upper end has a die-attaching region for carrying the optoelectronic device. The encapsulant covers at least the optoelectronic device, the first bonding part, and the carrying part.