Dual-Material Nanoparticle Adhesion Layer for Semiconductor Packages
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Solution Overview
Problem
Current methods for enhancing adhesion between diverse materials in semiconductor packages, such as leadframes and encapsulation compounds, are inadequate, especially as device miniaturization progresses, leading to issues like delamination and reduced moisture sensitivity due to rough surface treatments which negatively impact wire bonding and resin bleeding.
Innovation Solution
A dual-material nanoparticle adhesion layer is created by alternately depositing and sintering electrically conductive and non-conductive nanoparticles onto a substrate using a computer-controlled inkjet printer, forming a patterned layer that improves mechanical bonding and adhesion through interdiffusion and anchoring within the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the leadframe surface is roughened by chemical etching or metal plating to improve adhesion, then adhesion between leadframe and encapsulation compound is enhanced, but wire bonding quality deteriorates due to vision system difficulties, reduced capillary life, and degraded bonding consistency
Solution Approach 1:
The patent applies local quality by creating patterned adhesion zones only in specific regions where enhanced bonding is needed, rather than roughening the entire leadframe surface. The inkjet printing system deposits nanoparticles selectively on the chip attach pad area, maintaining smooth surfaces in wire bonding regions while providing roughened adhesion zones where required.
Solution Approach 2:
The patent segments the leadframe surface into distinct functional zones: patterned adhesion zones with deposited nanoparticles for enhanced bonding, and smooth zones for wire bonding operations. This segmentation allows each region to have optimized surface properties for its specific function.
2Strength
If general surface roughening is applied to improve adhesion, then interlocking with package material is enhanced, but resin bleeding increases which degrades moisture level sensitivity and interferes with down bonds
Solution Approach 1:
The patent confines the roughened adhesion layer to specific patterned zones using selective inkjet printing. By limiting nanoparticle deposition to only the chip attach pad regions, the patent prevents resin bleeding in surrounding areas while maintaining strong adhesion where needed.
3Volume of moving object
If device miniaturization is implemented to reduce package size, then device density is improved, but adhesion effectiveness diminishes making delamination more likely
Solution Approach 1:
The patent changes the surface morphology parameter by introducing nanoparticle patterns that create mechanical interlocking at the micro-scale. This parameter change enhances adhesion strength without requiring increases in package size, allowing miniaturization to proceed while maintaining 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
The dual-material nanoparticle layer enhances adhesion and mechanical bonding between metallic and polymeric materials, improving the reliability of semiconductor packages by maintaining adhesion at elevated temperatures and reducing resin bleeding, thus addressing the limitations of existing surface roughening techniques.
Implementation Method 1
The nozzles additively deposit a uniform layer comprising sequential and contiguous zones, alternating between the first solvent paste and the second solvent paste
Implementation Method 2
Energy is applied to sinter together the nanoparticles and diffuse the nanoparticles into the substrate
Implementation Method 3
Energy is applied to sinter together the nanoparticles and diffuse the nanoparticles into the substrate
Data Source
AI summary
Described examples include a substrate made of a first material and having a surface. First and second nozzles respectively dispense a first solvent paste including electrically conductive nanoparticles and a second solvent paste including non-conductive nanoparticles, while moving over the surface of the substrate. The first and second nozzles additively deposit a uniform layer including sequential and contiguous zones, alternating between the first solvent paste and the second solvent paste. Energy is applied to sinter together the nanoparticles and diffuse the nanoparticles into the substrate. The sintered nanoparticles form a layer composed of an alternating sequence of electrically conductive zones contiguous with electrically non-conductive zones.