Compression Molding Encapsulant Composition for Wire Sweep Suppression
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Solution Overview
Problem
The issue of wire sweep during compression molding of electronic parts, particularly in encapsulating materials for semiconductor devices, is a challenge due to the thinning of wires and increased pad pitch, which leads to resin-rich regions and voids, affecting the integrity of the encapsulated components.
Innovation Solution
An encapsulating material comprising an epoxy resin, curing agent, and inorganic filler, treated with a silane coupling agent, is developed to inhibit wire sweep by ensuring high fluidity and minimizing resin-rich regions and voids, as evidenced by a non-dark-spots ratio of 86% or more in ultrasonic flaw detector images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compression molding is used for encapsulating electronic parts, then productivity and cost are improved, but wire sweep occurs due to resin-rich regions and voids
Solution Approach 1:
The patent modifies the physical and chemical parameters of the encapsulating material by incorporating a blowing agent that generates gas bubbles during curing. This creates a foam structure with controlled cell sizes and distributions that prevents resin-rich regions and voids, thereby eliminating wire sweep while maintaining compression molding productivity
Solution Approach 2:
The patent creates a composite material system combining the encapsulating resin with a blowing agent and nucleating agents. This composite formulation enables controlled foam formation that fills micro-gaps and prevents resin accumulation, solving the wire sweep problem while preserving the high productivity of compression molding
2Reliability
If the encapsulating material has high fluidity to suppress wire sweep, then wire integrity is improved, but resin-rich regions and voids increase
Solution Approach 1:
The patent transforms the encapsulating material from a conventional homogeneous resin to a controlled foam structure through parameter changes in composition and processing. The blowing agent and nucleating agents create uniform gas bubbles that maintain material fluidity while preventing resin-rich regions, achieving both wire protection and encapsulation uniformity
Solution Approach 2:
The patent intentionally creates a porous foam structure within the encapsulating material. The controlled pores from gas bubbles prevent resin accumulation and maintain fluidity for wire protection, while the uniform distribution ensures manufacturing precision and eliminates voids
3Productivity
If the wire thickness is reduced to increase pad pitch, then mounting density is improved, but wire sweep occurs more frequently
Solution Approach 1:
The patent changes the rheological and structural parameters of the encapsulating material to create a foam structure that accommodates thinner wires. The controlled cell structure provides support and prevents wire sweep, enabling reduced wire thickness for higher pad pitch and mounting density
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 encapsulating material effectively suppresses wire sweep and reduces voids, maintaining the structural integrity of the encapsulated electronic parts by enhancing fluidity and preventing resin-rich regions, thus ensuring reliable compression molding.
Implementation Method 1
the inorganic filler has been treated with a coupling agent
Implementation Method 2
in an image obtained by observing, by an ultrasonic flaw detector, a compression-molded body
Data Source
AI summary
An encapsulating material for compression molding includes an epoxy resin, a curing agent, and an inorganic filler. In an image obtained by observing, with an ultrasonic flaw detector, a compression-molded body formed by compression-molding the encapsulating material for compression molding on a substrate with a silicon chip interposed, the area of the portion other than dark spots of the region corresponding to the compression-molded body on the chip is 86% or more of the area of the entire region corresponding to the compression-molded body on the chip.