Plasma-Coated Solder Oxidation Prevention
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Solution Overview
Problem
Conventional solder materials face issues with oxidation during storage and melting, leading to bonding defects such as decreased wetting extendability, bondability, and the occurrence of gaps (voids), which are not adequately addressed by existing flux-based methods or surface coating techniques that often result in uneven film thickness and increased production costs.
Innovation Solution
A coated solder material with a carbon-based coating film formed through atmospheric pressure plasma polymerization using an organic compound with a carbon number of 8 or less, which has a thickness of 4 nm to 200 nm and a mass-reduction rate of 60% or greater when heated, ensuring even coverage and preventing oxidation without impairing wetting extendability and bondability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating film is formed on the solder material surface to prevent oxidation, then oxidation resistance is improved, but film thickness uniformity deteriorates and production cost increases
Solution Approach 1:
The patent replaces conventional wet coating methods (mechanical application) with plasma polymerization (chemical/physical process). The plasma treatment creates a uniform carbon-containing coating film through chemical reactions rather than mechanical deposition, achieving both oxidation protection and thickness uniformity. The plasma process allows precise control of film properties through parameter adjustment (power, gas flow, treatment time) without the variability inherent in wet coating methods.
Solution Approach 2:
The patent utilizes plasma polymerization parameters (radio frequency power, gas composition, treatment duration, pressure) to precisely control the coating film characteristics. By adjusting these parameters, the process achieves consistent film thickness of 1-10 nm with uniform coverage, while incorporating carbon-containing groups that provide oxidation resistance. The parameter control enables reproducible results that eliminate the thickness variation problems of conventional coating methods.
2Reliability
If a thick coating film is formed to suppress oxidation, then oxidation resistance is improved, but wetting extendability and bondability deteriorate
Solution Approach 1:
The patent creates a coating film with specific local chemical properties by incorporating carbon-containing functional groups (carboxyl, carbonyl, hydroxyl groups) through plasma polymerization. This localized chemical modification provides oxidation resistance exactly where needed on the solder surface, while controlling the film thickness to remain thin (1-10 nm) to preserve wetting properties. The carbon-containing groups create a protective layer that is sufficiently thick to prevent oxidation but thin enough to allow good wetting and bonding performance.
3Reliability
If conventional flux is used to prevent oxidation, then oxidation resistance is improved, but electrical properties deteriorate and corrosion occurs
Solution Approach 1:
The patent employs a thin, sacrificial carbon-containing coating film formed by plasma polymerization that serves as a temporary protective barrier during storage and processing. This coating provides oxidation resistance similar to flux but without the harmful chemical residues. The carbon-based film is designed to be removed or decomposed during soldering reflow, leaving no corrosive residue that would degrade electrical properties or cause corrosion, unlike conventional flux materials.
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 coated solder material effectively prevents oxidation during long-term storage and melting, maintains excellent wetting extendability and bondability, and reduces the occurrence of gaps in bonded areas, while being efficiently produced with minimal production costs.
Implementation Method 1
a coating film including a carbon compound formed by radicalizing an organic compound introduced together with a carrier gas into a reaction gas that has been plasmatized under atmospheric pressure
Implementation Method 2
the coated solder material effectively prevents oxidation during long-term storage and melting
Data Source
AI summary
The present invention provides a coated solder material that is capable of preventing the advancement of oxidation of the surface during long-term storage and when melted, and that has excellent wetting extendability and bondability, without the occurrence of gaps in the bonded areas. A coating film is formed on the surface of a solder material; the coating film including a carbon compound that is formed by introducing an organic compound having a carbon number of 8 or less together with a carrier gas into a reaction gas that has been plasmatized under atmospheric pressure, and after a radicalized organic compound has been formed by radicalizing the organic compound, causing the radicalized organic compound to react with the metal on the surface of the solder material; the thickness of the coating film is 4 nm to 200 nm, and when heated at 150°C to 300°C and melted, the mass-reduction rate is 60% or greater.