Spray Coatable Adhesive for Narrow Silicon Die Bonding
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Solution Overview
Problem
Miniaturization of ejection chips in micro-fluid devices, such as inkjet printers, poses challenges in bonding and sealing due to the need for narrow and robust seals, precise alignment, and compatibility with inkjet printer environments, as existing high-viscosity adhesives struggle to form reliable bonds at widths smaller than 500 microns on densely patterned substrates.
Innovation Solution
A low-viscosity, spray-coatable adhesive composition comprising an epoxy-based resin, thermal acid generator, photoacid generator, and solvent, which can be cured by radiation and heat, allowing for precise bonding and sealing of silicon chips on substrates with narrow widths and providing robust adhesion in inkjet printer environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-viscosity die attach adhesive is dispensed through a needle, then reliable bonding is achieved, but the bond width cannot be reduced below 450-500 microns
Solution Approach 1:
The patent changes the viscosity parameter of the adhesive from high (60,000-100,000 cps) to low (suitable for spray coating), enabling the adhesive to be dispensed through spray nozzles and form narrow bond lines less than 500 microns wide while maintaining bonding reliability through optimized adhesive composition and spray coating parameters
2Volume of moving object
If ejection chip size is reduced for miniaturization, then material cost decreases, but bonding and sealing widths must be reduced to less than 500 microns which creates bonding challenges
Solution Approach 1:
The patent replaces the traditional needle dispensing mechanism with a spray coating mechanism that uses aerosolized adhesive particles deposited onto the substrate, enabling precise control of narrow bond lines and sealing widths less than 500 microns while maintaining manufacturing feasibility for miniaturized ejection chips
3Length of moving object
If adhesive viscosity is reduced for spray coatability, then narrow and robust seals can be formed, but adhesion strength may be compromised
Solution Approach 1:
The patent creates a composite adhesive formulation combining low-viscosity base adhesive with optimized concentrations of curing agents and additives, forming a multi-component system that maintains adhesion strength while enabling spray coatability and narrow seal widths less than 500 microns
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 composition enables uniform application, forming robust seals with narrow widths, maintaining adhesion between silicon dies and substrates, and resisting ink and corrosion, with minimal die movement and high adhesion strength, even after exposure to ink environments.
Implementation Method 1
a thermal acid generator
Implementation Method 2
a photoacid generator
Implementation Method 3
spray coatable adhesive composition
Data Source
AI summary
A spray coatable adhesive composition used for bonding silicon dies to a rigid substrate, preferable a silicon substrate is disclosed. The adhesive composition includes an epoxy based resin, a thermal acid generator, a photoacid generator and a solvent. The epoxy based resin includes a mixture of a solid bisphenol A epoxy resin and a liquid or semi-liquid hydrogenated bisphenol A epoxy resin at a weight ratio ranging from about 80:20 to about 65:35. The adhesive composition has a low viscosity which allows it to be spray coated on a rigid substrate and form thin film adhesive which allows silicon dies to be bonded with precise placement on the silicon substrate.