Solid Electrolytic Capacitor Laser Welding Protection

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Solution Overview

Problem

Conventional solid electrolytic capacitors face issues with laser welding due to the close proximity of the laser to the anode wire and termination, leading to potential deflection and contact with the solid electrolyte, causing carbonization and poor electrical properties.

Innovation Solution

A solid electrolytic capacitor with a multi-layered protective coating comprising a light reflective layer and a stress dissipation layer is employed, which includes non-metallic reflective particles and conductive metal particles to minimize light contact with the solid electrolyte and dissipate stresses, respectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If laser welding is used to connect the anode wire to the termination, then the electrical connection is improved, but the solid electrolyte may be carbonized due to laser deflection

Engineering Contradiction:

Improveelectrical connectionVSAvoidcarbonization of solid electrolyte

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A reflective coating layer is applied to the solid electrolyte surface to act as an intermediary that reflects the laser beam away from the solid electrolyte. This mediator prevents the harmful laser energy from directly contacting and carbonizing the solid electrolyte, while still allowing the laser welding process to proceed effectively for connecting the anode wire to the termination.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The reflective coating is applied in advance before the laser welding process to pre-establish protection against laser-induced carbonization. This preliminary protective action ensures that when the laser is subsequently used for welding, the solid electrolyte is already shielded from potential harmful effects.

Inventive Principle:

Principle #9Preliminary anti-action

2Volume of moving object

If the laser is positioned close to the anode wire and termination for small case sizes, then the capacitor size is reduced, but the laser beam is readily deflected onto the solid electrolyte

Engineering Contradiction:

Improvecapacitor sizeVSAvoidlaser beam deflection onto solid electrolyte

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The reflective coating serves as a mediator that allows the laser to be positioned close to the anode wire and termination for compact capacitor design, while simultaneously preventing the deflected laser beam from damaging the solid electrolyte. The coating enables close positioning without the harmful consequences.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The laser beam that would normally be deflected harmfully onto the solid electrolyte is instead reflected by the coating in a controlled manner. The potential harmful deflection is converted into a beneficial reflection pattern that protects the solid electrolyte while still enabling effective welding at close distances.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 solution effectively reduces the risk of carbonization and maintains excellent electrical properties, such as low ESR and leakage currents, during the laser welding process.

Implementation Method 1

a light reflective layer overlies the solid electrolyte... The light reflective layer contains a plurality of non-metallic reflective particles

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

a stress dissipation layer overlies the light reflective layer... The stress dissipation layer includes a plurality of metal particles

Methodology Applied

Scientific EffectStress dissipation: Stress Relaxation

Data Source

PatentUS8355242B2Solid electrolytic capacitor element

Publication Date: 2013.01.15 KYOCERA AVX COMPONENTS CORP

AI summary

A solid electrolytic capacitor element that is capable of withstanding laser welding without a significant deterioration in its electrical performance is provided. The capacitor element contains an anode body, dielectric, and solid electrolyte. To help shield the solid electrolyte from damage that might otherwise occur during manufacture of the capacitor, a multi-layered protective coating is employed in the present invention that overlies at least a portion of the solid electrolyte. More particularly, the protective coating includes a light reflective layer overlying the solid electrolyte and a stress dissipation layer overlying the light reflective layer. The light reflective layer can help reflect any light that inadvertently travels toward the capacitor during, for example, laser welding. This results in reduced contact of the solid electrolyte with the laser and thus minimizes defects in the electrolyte that would have otherwise been formed by carbonization. The stress dissipation layer can likewise help to dissipate stresses experienced by the capacitor (e.g., during encapsulation, reflow, etc.) so that they are not as likely to cause damage to the solid electrolyte. The stress dissipation layer can also be relatively porous in nature so that humidity trapped in the capacitor can escape and diminish the pressure that might otherwise be transferred to the solid electrolyte.