UV-Curable Adhesive Dicing for Semiconductor Chip Separation
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Solution Overview
Problem
The increasing size and thinness of semiconductor chips make chip pick-up after dicing difficult due to intermixing of die attach films and adhesive layers at the dicing line, leading to poor separability and pick-up errors.
Innovation Solution
A dicing method involving a UV-curable adhesive laminated onto a substrate film, with a semiconductor wafer laminated on top, where UV irradiation is applied before dicing to reduce adhesive strength and increase cohesive force, facilitating easier separation of the die attach film and adhesive sheet during chip pick-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UV irradiation is applied before dicing to reduce adhesive strength, then chip pick-up separability is improved, but adhesive bonding strength during dicing deteriorates
Solution Approach 1:
The patent applies preliminary UV irradiation to the adhesive layer before the dicing process to partially cure the adhesive, reducing its tackiness and preventing excessive bonding between the die attach film and adhesive layer during dicing. This preliminary action controls the adhesive properties in advance to ensure clean separation during chip pick-up while maintaining sufficient bonding strength for the dicing process.
2Ease of manufacture
If die attach film and adhesive layer are laminated together, then manufacturing process is simplified, but intermixing at dicing line increases
Solution Approach 1:
The patent changes the physical and chemical parameters of the adhesive layer by applying UV irradiation to modify its curing degree. This parameter change reduces the adhesive layer's tackiness and bonding strength to a controlled level, preventing intermixing between the die attach film and adhesive layer at the dicing line while maintaining the laminated structure for manufacturing simplicity.
3Reliability
If adhesive strength is reduced for easier separation, then pick-up error rate decreases, but bonding reliability during assembly deteriorates
Solution Approach 1:
The patent applies preliminary UV irradiation to the adhesive layer before dicing to partially cure the adhesive, reducing its tackiness to prevent excessive bonding during dicing. This preliminary action ensures clean separation during chip pick-up. The adhesive then provides sufficient bonding strength during the assembly process, achieving both pick-up accuracy and bonding reliability.
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 method reduces intermixing of die attach film and adhesive layers at the dicing line, enhancing chip pick-up reliability and reducing pick-up errors by lowering adhesive strength while maintaining cohesive force.
Implementation Method 1
a UV irradiation step of irradiating the UV-curable adhesive with UV rays
Data Source
AI summary
With the invented dicing method, by increasing the cohesive strength while decreasing the adhesive strength of an ultraviolet-curing adhesive in advance, mixing of the ultraviolet-curing adhesive layer of an adhesive sheet with a die attach film on a dicing line can be decreased and pickup failures can be reduced, when picking up chips having a die attach film after dicing. The dicing method for a semiconductor wafer with a die-attach film comprises a first gluing step in which a die attach film is affixed to an adhesive sheet having an ultraviolet-curing adhesive laminated on a base material film, a second gluing step in which a semiconductor wafer is affixed to the opposite side of the die attach film affixed to the adhesive sheet, an ultraviolet irradiation step in which the ultraviolet-curing adhesive is irradiated with ultraviolet light, and a dicing step in which the semiconductor wafer and the die attach film affixed to the adhesive sheet are diced.