Adhesive Sheet for Semiconductor Dicing with Controlled Tack
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Solution Overview
Problem
In the dicing process of semiconductor wafers, the high-speed rotating thin grinding wheel scrapes up adhesive from adhesive sheets, causing adhesive attachment to diced chips, which leads to yield reduction and adhesive transfer issues.
Innovation Solution
An adhesive sheet with a substrate film and an adhesive layer containing (meth)acrylate copolymer, photopolymerizable compound, softener, curing agent, and photopolymerization initiator, where the photopolymerizable compound has a weight average molecular weight of 40,000 to 220,000, and the adhesive layer is irradiated with activating rays to reduce tack strength and prevent adhesive transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the adhesive layer has high tack strength to hold chips during dicing, then chip retention is improved, but adhesive scraping by the grinding wheel increases causing adhesive transfer
Solution Approach 1:
The patent changes the molecular weight parameter of the photopolymerizable compound to a specific range (40,000 to 220,000) to optimize the adhesive's properties. This parameter change allows the adhesive to have appropriate tack strength for chip retention while reducing its tendency to be scraped by the grinding wheel, thus resolving the contradiction between holding power and scraping resistance.
Solution Approach 2:
The adhesive layer is formulated as a composite material containing (meth)acrylate copolymer, photopolymerizable compound with specific molecular weight, softener, curing agent, and photopolymerization initiator. This composite formulation balances the competing requirements of tack strength and scraping resistance by combining materials with complementary properties.
2Object-generated harmful factors
If ultraviolet rays are irradiated to polymerize the adhesive layer and reduce tack strength for picking up, then adhesive transfer is reduced, but the dicing process must be completed before this treatment
Solution Approach 1:
The adhesive layer is pre-formulated with photopolymerizable compounds that can be cured by ultraviolet irradiation. This preliminary preparation allows the adhesive to maintain appropriate tack strength during dicing, then be rapidly cured after dicing to prevent adhesive transfer during chip picking up, thus resolving the timing sequence issue.
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 adhesive sheet effectively inhibits adhesive scraping during dicing, prevents chip detachment, and facilitates easy picking up of semiconductor chips without adhesive transfer, improving processing yield and efficiency.
Implementation Method 1
an adhesive layer that develops polymerization curing reaction by ultraviolet rays and the like
Data Source
AI summary
An adhesive sheet is provided that is capable of inhibiting scraping up of an adhesive in the dicing step, does not cause chip detachment during dicing processing, facilitates picking up, and does not readily develop adhesive transfer. According to the present invention, an adhesive sheet is provided that comprises a substrate film and an adhesive layer laminated on the film, wherein the adhesive layer contains 100 parts by mass of a (meth)acrylate copolymer, from 5 to 250 parts by mass of a photopolymerizable compound, from 20 to 160 parts by mass of a softener, from 0.1 to 30 parts by mass of a curing agent, and from 0.1 to 20 parts by mass of a photopolymerization initiator, and the photopolymerizable compound has a weight average molecular weight from 40,000 to 220,000.