Conductive pastes using bimodal particle size distribution
AssigneeCn Innovations Limited
InventorKa Ming Ng
Life of this patent
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Abstract
Monodispersed metal nanoparticles are prepared by preparing a homogeneous metal complex solution by mixing metal salt with a complexing agent in solvent. A precipitating agent is added into the homogeneous metal complex solution to form a slurry. A homogeneous mixture of reducing agent and solvent is added to perform reducing reaction on the slurry to form metal nanoparticles in a controlled environment under gas purge. A capping agent is added to modify surface properties of metal nanoparticles. The metal nanoparticles are washed and the metal nanoparticles are recovered by phase extraction or centrifugation. The technique can be used to prepare conductive pastes with bimodal particle size distribution.
Claims11
A method to prepare conductive pastes with bimodal particle size distribution, comprising the steps of:
- dispersing micron-sized or finer metal fillers and metal nanoparticles with a mass ratio ranging from 1:0.05 to 1:20 in a low boiling point solvent to form a suspension, wherein the low boiling point solvent has a boiling point lower than 100° C., wherein the micron-sized or finer metal fillers comprise micron-sized or finer copper fillers, the micron-sized or finer copper fillers being shaped as flakes, platelets or a combination thereof, wherein each said micron-sized or finer copper filler is sized in a range of 1 μm to 1000 μm with an aspect ratio range of 2 to 30;
- adding a binder to a high boiling point solvent to form a binder matrix, wherein the high boiling point solvent has a boiling point between 100° C. and 300° C.;
- adding the suspension into the binder matrix to form a paste precursor;
- and
- heating the paste precursor at an elevated temperature to remove the low boiling point solvent to obtain a paste with bimodal particle size distribution, the viscosity of the paste ranging from 50 cP to 500,000 cP.
Dependencies are inferred from the claim text.