Viscous Adhesive Tape Composition for Clean QFN Leadframe Peeling
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Solution Overview
Problem
In QFN semiconductor device production, existing viscous adhesive tapes fail to prevent resin burrs during sealing while maintaining adhesion strength and avoiding adhesive residues upon peeling, leading to issues like soldering failures and yield degradation.
Innovation Solution
A viscous adhesive tape with a semi-interpenetrating polymer network structure, comprising a first acrylic resin with an acid value of 30-100 mg KOH/g and a second acrylic resin with an acid value of 0-10 mg KOH/g, in a specific ratio, along with an epoxy resin curing agent, to achieve optimal adhesion and pollution resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a viscous adhesive tape with high adhesion strength is used to prevent resin leakage, then resin burrs are prevented, but adhesive residues remain on the leadframe after peeling
Solution Approach 1:
The patent applies parameter changes by carefully controlling the acid value of the acrylic resin within 30-100 mg KOH/g and using a specific molecular weight range (50,000-500,000). These parameter optimizations enable the adhesive to provide sufficient bonding strength during sealing while allowing clean peeling without residues, resolving the contradiction between adhesion strength and residue prevention.
Solution Approach 2:
The patent uses composite materials by formulating the adhesive layer as a copolymer containing both carboxylic group-containing (meth)acrylic tacky polymer and amino group-containing (meth)acrylic non-tacky polymer. This composite structure combines the high adhesion of tacky components with the clean-release properties of non-tacky components, achieving both strong bonding and residue-free peeling.
2Strength
If the acid value of acrylic resin is increased to improve adhesion, then bonding strength increases, but resin burrs occur during sealing
Solution Approach 1:
The patent applies parameter changes by defining a specific acid value range (30-100 mg KOH/ g) and molecular weight range (50,000-500,000) for the acrylic resin. This optimized parameter range achieves the optimal balance where the adhesive provides sufficient bonding strength to prevent resin leakage while maintaining flexibility and elasticity that prevent resin burr formation during the sealing 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 solution effectively prevents resin burrs during sealing and ensures no adhesive residues upon peeling, maintaining compatibility between adhesion properties and pollution resistance.
Implementation Method 1
the carboxylic group-containing (meth)acrylic tacky polymer having a weight average molecular weight of less than 800,000 and a glass transition temperature of -100° C to -30° C
Implementation Method 2
the amino group-containing (meth)acrylic non-tacky polymer having a weight average molecular weight of from 30,000 to 100,000 and a glass transition temperature of 20° C to 90° C
Data Source
Figure 1(a)~1(g)
AI summary
A viscous adhesive tape comprises a tack layer containing a first acrylic resin having an acid value of 30 to 100 mg KOH/g and a second acrylic resin having an acid value of 0 to 10 mg KOH/g, wherein the ratio between the first acrylic resin and the second acrylic resin is, (First acrylic resin):(Second acrylic resin)=85:15 to 65:35, and the first acrylic resin and the second acrylic resin have a semi-interpenetrating polymer network structure.