Local-Cure Chip Encapsulation for Saw-Free Die Separation
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Solution Overview
Problem
Conventional chip packaging methods are inefficient and require time-consuming processes such as sawing through hardened encapsulant material and individual pick and place operations, which limit throughput and can lead to mechanical damage to bare silicon dies.
Innovation Solution
A method involving the use of a locally curable encapsulant material that is selectively cured around individual chips, allowing for easy separation of encapsulated chip sections at mechanically weak, uncured interfaces, eliminating the need for sawing and pick and place processes by using a photo imaging polymer sheet and UV curing to define encapsulation boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional encapsulation methods are used with hardened material, then reliable protection and electrical insulation are achieved, but time-consuming sawing and pick-and-place operations are required
Solution Approach 1:
The patent changes the physical state of the encapsulant from fully cured (hard) to partially uncured (soft) at specific locations. By controlling the curing parameter spatially, the encapsulant remains soft between chips to enable easy separation while maintaining protection around individual chips, eliminating sawing operations and increasing throughput
2Reliability
If conventional encapsulation methods are used with hardened material, then reliable protection is achieved, but mechanical damage to bare silicon dies may occur
Solution Approach 1:
The patent applies different mechanical properties to different regions of the encapsulant: cured (hard) regions provide protection around individual chips, while uncured (soft) regions between chips prevent mechanical damage during separation. This local differentiation of material properties eliminates the need for harsh sawing operations that could damage bare silicon dies
3Manufacturing precision
If individual pick and place operations are used, then precise chip placement is achieved, but operational complexity and time consumption increase
Solution Approach 1:
The patent segments the encapsulant's curing state into chip-specific cured regions and inter-chip uncured regions. This segmentation allows chips to remain precisely positioned during encapsulation while enabling simple mechanical separation at the uncured interfaces, eliminating complex pick-and-place operations and reducing operational complexity
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
This approach simplifies the packaging process, increases throughput, and provides reliable protection and electrical insulation for chips while enabling bulk packaging without the need for additional encapsulation steps, reducing mechanical stress and operational complexity.
Implementation Method 1
The encapsulant may comprise a photo imaging polymer and a photoinitiator promoting curing of the photo imaging polymer when being irradiated with electromagnetic radiation
Implementation Method 2
irradiated with electromagnetic radiation, such as ultraviolet radiation
Data Source
AI summary
A method of processing chips is disclosed. In one example, the method comprises encapsulating mutually spaced chips by an encapsulant comprising a locally curable material. The encapsulated chips with the encapsulant are separated into a plurality of encapsulated chip sections by locally curing selectively portions of the encapsulant covering at least a portion of the chips without curing other portions of the encapsulant apart from the encapsulated chip sections.