Leadframe Sacrificial Anode Protection Against Corrosion

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Solution Overview

Problem

Conventional methods for protecting leadframes from oxidation/corrosion, such as altering alloy conditions or coating, are unsatisfactory and can affect mechanical properties or increase processing costs, and different coatings alter surface energies affecting epoxy bleed-out.

Innovation Solution

A method involving a leadframe with a first standard electrode potential and a protection material with a lower second standard electrode potential, where the protection material acts as a sacrificial anode to protect the leadframe as a cathode from corrosion/oxidation, without altering the leadframe's alloying conditions or requiring additional tooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the alloying condition of the leadframe is changed to protect from oxidation/corrosion, then the corrosion resistance is improved, but the mechanical properties of the leadframe are affected

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidmechanical properties

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

A protection material with lower standard electrode potential is introduced as an intermediary between the leadframe and the corrosive environment. This protection material acts as a sacrificial anode, preferentially oxidizing to protect the leadframe without requiring changes to the leadframe's alloying composition, thus maintaining mechanical properties while improving corrosion resistance

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If coating is applied to the leadframe to protect from oxidation/corrosion, then the corrosion resistance is improved, but the processing cost increases due to electrochemical procedures and additional tooling

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidprocessing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The protection material is designed as a consumable sacrificial anode that is cheaper than the leadframe material. It is intentionally allowed to oxidize and be consumed over time, providing ongoing protection without requiring expensive electrochemical coating processes or specialized tooling like masking and LDI equipment

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The protection material serves as a sacrificial intermediary that absorbs the corrosive attack, eliminating the need for complex electrochemical coating procedures and reducing manufacturing costs while maintaining corrosion protection

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If different materials are coated to the leadframe to protect from oxidation/corrosion, then the corrosion resistance is improved, but the surface energy changes affecting epoxy bleed out

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidsurface energy compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The protection material acts as a sacrificial intermediary that protects the leadframe surface without forming a permanent coating layer that would alter surface energy. Since the protection material is consumed through oxidation, the original leadframe surface properties including surface energy and epoxy bleed-out characteristics are preserved

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Effectively protects the leadframe from corrosion/oxidation while maintaining its mechanical, electrical, and thermal properties, and avoiding increased processing costs, without interfering with its functionality or requiring complex fixation methods.

Implementation Method 1

contacting the protection material with the leadframe so that the protection material acts as a sacrificial anode to protect the leadframe as a cathode from corrosion/oxidization

Methodology Applied

Scientific EffectSacrificial anode protection: Galvanometer

Implementation Method 2

providing a protection material of a second standard electrode potential, the second standard electrode potential being lower than the first standard electrode potential

Methodology Applied

Scientific EffectElectrochemical corrosion protection: Redox Reactions

Data Source

PatentUS12479645B2Method for protecting leadframe, leadframe composite, box and outside container

Publication Date: 2025.11.25 ADVANCED ASSEMBLY MATERIALS ANHUI LTD

AI summary

A method (10) for protecting leadframe, a leadframe composite (20), a box (26) and an outside container (34) are provided. The method (10) includes: step (12), providing a leadframe (22) of a first standard electrode potential; step (14), providing a protection material (24) of a second standard electrode potential, the second standard electrode potential being lower than the first standard electrode potential; and step (16), contacting the protection material (24) with the leadframe (22) so that the protection material (24) acts as a sacrificial anode to protect the leadframe (22) as a cathode from corrosion/oxidization. Embodiments of the present disclosure may help to protect the leadframe (22) without changing the alloying condition of the leadframe (22), without increasing the processing cost of the leadframe (22), etc.