Heat-shrinkable Tape Wafer Division Method
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Solution Overview
Problem
Existing wafer dividing methods face challenges in maintaining the spacing between chips due to high tension in heat-shrinkable tapes, leading to difficulties in picking up chips as the tape shrinks, especially when dealing with small chip sizes.
Innovation Solution
A wafer dividing method and apparatus that uses a heat-shrinkable tape attached to a ring frame, where the tape is expanded and then heat-shrunk to maintain the spacing between chips, with a lifting unit and heater to control the expansion and shrinkage, ensuring the tape's shape is maintained and the chip spacing is preserved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the tape is largely expanded to divide a wafer with small chip size, then the chip division is achieved, but the high tension applied to the tape causes large shrinking force during elastic recovery, making it difficult to maintain the tape shape by suction force
Solution Approach 1:
The patent applies preliminary action by pre-heating the heat-shrinkable tape before expansion to activate its heat-shrinkable properties. This preliminary thermal treatment ensures that the tape is in a relaxed state during expansion, reducing elastic recovery tension. After chip division, the tape is heated again to trigger controlled shrinkage that maintains chip spacing without causing excessive shrinking forces during the division process.
Solution Approach 2:
The patent utilizes parameter changes by controlling the temperature of the heat-shrinkable tape to alter its mechanical properties. By heating the tape to its transition temperature, the tape's elasticity and shrinkage characteristics are modified. This allows the tape to expand freely during division and then shrink controllably after division to maintain chip spacing, resolving the contradiction between achieving division and maintaining shape stability.
2Manufacturing precision
If the tape is heat shrunk to maintain chip interval, then the chip spacing is preserved, but the high shrinking force causes the chips to contact each other and be broken
Solution Approach 1:
The patent applies local quality by selectively heating only the heat-shrinkable tape regions between the chips rather than the entire wafer assembly. The heating unit is positioned to target specific zones where the tape needs to shrink, allowing controlled localized shrinkage that maintains chip spacing without applying excessive force that could break the chips. This localized approach enables precise control over the shrinking process.
Solution Approach 2:
The patent employs periodic action through a controlled heating process that occurs in stages: first heating the tape before expansion, then heating again after expansion to trigger shrinkage. This periodic thermal treatment allows the system to transition between different states (relaxed, expanded, shrunk) in a controlled manner, ensuring chip spacing is maintained while avoiding excessive shrinking forces that could damage the chips.
3Stability of the object's composition
If the suction force of the holding table is used to maintain tape shape, then the tape stability is improved, but the suction force becomes insufficient when high tension is applied to the tape during large expansion
Solution Approach 1:
The patent changes the physical state of the heat-shrinkable tape by controlling its temperature. By heating the tape to its transition temperature before and during expansion, the tape's mechanical properties are altered to reduce elastic recovery tension. This parameter change (temperature) enhances the effectiveness of the suction force in maintaining tape stability during large expansions, resolving the contradiction between tape stability and suction force sufficiency.
Solution Approach 2:
The heat-shrinkable tape itself acts as an intermediary that mediates between the suction force and the chip division process. By pre-heating the tape, its elastic properties are modified so that it can be expanded to large dimensions while still being maintainable by the suction force. The heated tape's reduced elastic recovery tension allows the suction force to effectively maintain stability during the division process.
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 method effectively maintains the spacing between adjacent chips, preventing them from contacting each other and ensures proper pick-up of chips by controlling the tape's expansion and heat-shrinkage, even after the tape has relaxed, thus addressing the issue of chip spacing maintenance.
Implementation Method 1
a heater adapted to heat the tape in a ring shape between an outer periphery of the wafer and an inner periphery of the ring frame of the work set
Implementation Method 2
the expanded tape is suction held by a holding table so as to maintain the shape of the tape
Data Source
AI summary
A wafer is divided at division starting points along division lines to form a predetermined gap between adjacent chips. Next, that area of a tape to which the wafer is adhered is suction held by a table, after which the table and a ring frame holding section are relatively moved further away from each other to expand the tape in a ring shape between an outer periphery of the wafer and an inner periphery of a ring frame. Thereafter, the table and the ring frame holding section are relatively moved closer to each other to slacken the ring-shaped tape, and the ring-shaped tape is heated by a heater, to heat shrink the tape and to maintain the predetermined gap between the adjacent chips.