Non-Circular Die Stretching for Rectangular Die Transfer
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Solution Overview
Problem
Conventional methods for stretching a die source with a circular configuration result in inconsistent and undesirable shapes, such as a barrel shape, when transferring semiconductor or LED die from a rectangular configuration to a substrate.
Innovation Solution
The use of a stretch ring and driving member with non-circular cross-section or internal shape to maintain the rectangular configuration of the die source during stretching, allowing for controlled expansion and transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a circular driving member is used to stretch a rectangular die source, then the area occupied by the die source is increased, but the die source shape becomes inconsistent and distorted (barrel shape)
Solution Approach 1:
The patent applies asymmetry by changing the driving member from a circular (symmetric) shape to a rectangular (asymmetric relative to circular) shape. This rectangular driving member contacts the rectangular die source in a manner that preserves the rectangular configuration during stretching, preventing the barrel-shaped distortion that occurs with circular driving members. The asymmetric geometry of the driving member matches the asymmetric geometry of the die source, enabling uniform expansion while maintaining shape consistency.
2Ease of operation
If the die source is stretched to increase spacing between die, then transfer of individual die becomes easier, but the die source configuration becomes distorted
Solution Approach 1:
The rectangular driving member provides asymmetric contact that preserves the rectangular configuration of the die source during stretching. This maintains equal spacing between die in both horizontal and vertical directions, creating uniform gaps that facilitate consistent pick-and-place transfer operations. The asymmetric geometry prevents the barrel distortion that would create uneven spacing and complicate transfer operations.
3Area of moving object
If a circular stretch ring is used to hold the carrier sheet, then the die source can be stretched, but rectangular configuration cannot be maintained
Solution Approach 1:
The patent employs asymmetry by replacing the circular stretch ring with a rectangular stretch ring that has straight edges and corners matching the rectangular die source geometry. This rectangular configuration allows the die source to be stretched uniformly in both horizontal and vertical directions while maintaining the rectangular shape. The asymmetric geometry of the stretch ring prevents the radial expansion pattern of circular rings that causes barrel-shaped distortion.
Data Source
AI summary
A system for stretching a die source is provided. The system includes: a stretch ring for holding a carrier sheet, the carrier sheet supporting a die source, the die source including a plurality of die; and a driving member for contacting the carrier sheet through the stretch ring, an area occupied by the die source being increased by contact between the driving member and the carrier sheet. At least one of (a) a cross section of the driving member, and (b) an internal shape of the stretch ring, is non-circular.