Leadframe Plating Bath Shielding Using Inert Gas Bubble Curtains

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Solution Overview

Problem

Adhesion promoters like silver oxide dissolve in acidic solder plating baths when leadframes are left for extended periods, leading to delamination issues in semiconductor device manufacturing.

Innovation Solution

A method involving gas bubble curtains formed by inert gas, such as nitrogen, to shield leadframes from prolonged contact with the plating bath, using partitioning walls to create a protected compartment during equipment stops.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If leadframes are left in the solder plating bath for extended periods, then the bath has time to process the articles, but the adhesion promoter dissolves causing delamination issues

Engineering Contradiction:

Improveresidence time in plating bathVSAvoidadhesion between resin and leadframe

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

A gas barrier (inert gas or air) is introduced as an intermediary layer between the leadframes and the plating bath solution. This gas barrier prevents direct contact between the adhesion promoter on the leadframe surface and the dissolving chemicals in the bath, while still allowing the plating process to proceed effectively when the barrier is removed or reduced.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

An inert gas atmosphere is created above the plating bath surface to prevent dissolution of the adhesion promoter. The inert gas environment protects the organic adhesion promoter from chemical degradation and dissolution into the aqueous plating bath, maintaining its integrity during extended residence times.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Ease of operation

If equipment stops during processing, then operational issues can be addressed, but articles remain in prolonged contact with the bath causing adhesion promoter dissolution

Engineering Contradiction:

Improveequipment stop capabilityVSAvoidadhesion promoter stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

A gas barrier is established in advance before equipment stops occur, or is quickly activated upon stop detection. This preliminary protective action ensures that if a stoppage occurs, the adhesion promoter is already protected from dissolution, allowing operators to address equipment issues without compromising adhesion integrity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The gas barrier acts as a protective cushion that is in place before harmful dissolution can occur during equipment stoppages. This beforehand protection allows the system to withstand operational interruptions without suffering the adverse effects of adhesion promoter dissolution.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If articles are moved continuously through the bath, then processing efficiency is maintained, but any halt results in immediate adhesion promoter dissolution

Engineering Contradiction:

Improveprocessing throughputVSAvoidadhesion promoter dissolution during stops

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The gas barrier serves as a mediator that decouples the relationship between processing continuity and adhesion promoter stability. During continuous operation, the barrier can be minimal or absent for high productivity; during stops, the barrier is activated to prevent dissolution, allowing flexible operation without compromising adhesion.

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

Prevents adhesion promoter dissolution, maintaining adhesion between resin and metal, and facilitates quick recovery of plating equipment operation.

Implementation Method 1

providing a gas flow lapping the opposed surfaces of the articles (14) wherein gas flow shields said opposed surfaces from exposure to the processing bath (B)

Methodology Applied

Scientific EffectGas flow shielding:

Implementation Method 2

nozzles configured to form, during an equipment stop, protective gas bubble curtains that counter prolonged contact of articles being processed

Methodology Applied

Scientific EffectBubble curtain formation: Bubble

Data Source

PatentUS12601082B2Method of processing articles and corresponding apparatus

Publication Date: 2026.04.14 STMICROELECTRONICS SRL

AI summary

Articles such as substrates for semiconductor products comprising metal and resin portions with adhesion promoter material are processed in a plating bath, wherein the adhesion promoter material is exposed to dissolution as a result of prolonged exposure to the plating bath. The articles are processed by dipping them in the processing bath so that they have opposed surfaces exposed to the processing bath.The movement of the articles through the processing bath B may occur to be halted. In that case a gas flow is provided lapping the opposed surfaces of the articles to shield the opposed surfaces of the articles from exposure to the processing bath.