Rosin Micro-Sphere Coating for Circuit Board Corrosion Protection
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Solution Overview
Problem
Existing conformal coatings for electronic circuitry fail to adequately protect against harsh environmental conditions such as moisture, dust, and chemicals, particularly in extreme usage scenarios.
Innovation Solution
Application of rosin micro-spheres to electronic components, followed by heating to cause them to flow and crosslink, forming a protective rosin coating that covers the circuit board or selected components, using a flexible sheet material like polyimide tape with silicone adhesive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conformal coatings (acrylic, epoxy, urethane, or silicone resin) are applied to electronic circuitry, then the circuitry is protected against moisture, dust, and chemicals, but the protection is insufficient in harsh environmental conditions
Solution Approach 1:
The patent changes the chemical composition parameters of the coating material from conventional acrylic, epoxy, urethane, or silicone resins to rosin-based flux composition. This parameter change transforms the coating's protective properties, enabling it to withstand harsh environmental conditions including moisture, dust, and chemicals more effectively than conventional coatings.
Solution Approach 2:
The invention uses a composite material system consisting of rosin as the base material combined with flux activators. This composite formulation creates a coating that integrates multiple functional properties: protective barrier characteristics from rosin and enhanced performance against environmental hazards from the flux activators, achieving superior reliability in harsh conditions.
2Reliability
If rosin micro-spheres are heated to cause them to flow and crosslink, then a protective coating is formed, but energy is consumed during the heating process
Solution Approach 1:
The patent utilizes phase transition of the rosin micro-spheres from solid to liquid state through heating. The micro-spheres are heated to their melting point, causing them to flow and form a continuous coating layer. As the coating cools, it crosslinks and solidifies, creating a durable protective barrier. This phase transition mechanism enables effective coating formation with controlled energy input.
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 rosin coating effectively creates a barrier against environmental contaminants and corrosive gases, preventing corrosion and residue impact on electronic components, while allowing easy repair by maintaining solderability.
Implementation Method 1
heating the rosin micro-spheres to a temperature of at least 55° C. for a time sufficient to cause said micro-spheres to flow
Implementation Method 2
heating the rosin micro-spheres to a temperature of at least 55° C. for a time sufficient to cause said micro-spheres to flow and for the rosin to crosslink
Data Source
AI summary
A method for protecting an assembled circuit board by providing a layer of rosin micro-spheres directly on the components to be protected, heating the micro-spheres to a temperature of about 65° C. for a time sufficient to cause the micro-spheres to flow and the rosin to crosslink, and then allowing the board to cool until the rosin returns to its solid state. The rosin micro-spheres may be put onto the board and components by first loading the microspheres onto a transfer tape and then positioning the transfer tape, microspheres down, over the components to be protected. After the rosin is heated the tape may be removed. The method is effective for protecting assembled boards against airborne S to prevent creep corrosion of the copper metallization, and for protecting against Sn to prevent the formation of tin whiskers in tin-plated or soldered lead-free assemblies.