Stabilizing PCB Resistance via Vapor Phase Soldering

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Solution Overview

Problem

The electrical resistance between conductor tracks on printed circuit boards is significantly affected by temperature and humidity fluctuations, leading to instability and potential failures in electronic components.

Innovation Solution

Treating the printed circuit board in a vapor phase soldering system using a heat transfer medium, such as perfluoropolyether, at controlled temperatures (200°C to 260°C) and pressures (10 mbar to 100 mbar) to stabilize the resistance, with the process repeated multiple times to enhance stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional printed circuit boards are used without special treatment, then manufacturing is simple and cost-effective, but the electrical resistance between conductor tracks is significantly affected by temperature and humidity fluctuations

Engineering Contradiction:
Improvestability of electrical resistanceVSAvoidcomplexity of manufacturing process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The solder resist is pre-treated in a vapor phase soldering system before final assembly, stabilizing its properties in advance to prevent subsequent resistance variations caused by temperature and humidity changes

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The vapor phase soldering process exposes the solder resist to controlled temperature (200-260°C) and pressure (10-100 mbar) conditions, fundamentally changing the physical and chemical parameters of the material to achieve long-term stability

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the printed circuit board is treated in a vapor phase soldering system at high temperature and pressure, then the electrical resistance stability is improved, but the manufacturing process becomes more complex and time-consuming

Engineering Contradiction:
Improvestability of electrical resistanceVSAvoidmanufacturing cycle time
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The treatment process is applied in periodic cycles (multiple passes through the vapor phase soldering system), with each cycle contributing to progressive stabilization of the solder resist properties

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The vapor phase soldering process utilizes phase transition of the heat transfer medium (perfluoropolyether) from liquid to vapor and back, providing controlled thermal energy transfer that stabilizes the solder resist without excessive heating time

Inventive Principle:
Principle #36Phase transitions

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 method effectively reduces the impact of temperature and humidity changes on electrical resistance, maintaining a stable resistance value over time, even under extreme environmental conditions, thereby ensuring reliable component soldering and performance.

Implementation Method 1

treating the printed circuit board in a vapor phase soldering system using a heat transfer medium

Methodology Applied
Scientific EffectVapor phase heat transfer: Phase Change

Implementation Method 2

vapor phase soldering system at temperatures between 200°C and 260°C and at pressures of between 10 mbar and 100 mbar

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3375264B1Process to stabilize the resistance between conductive tracks
Publication Date: 2020.08.05 ENDRESS & HAUSER GMBH & CO KG
  • EP3375264B1 patent drawingFigure 1~2
  • EP3375264B1 patent drawingFigure 3a~3b

AI summary

The invention relates to a method for stabilizing the electric resistance between printed conductors (2) on a printed circuit board (1) that comprises solder resist in areas to be insulated between the printed conductors (2), said method involving the step of treating the printed circuit board (1) in a vapor-phase soldering system by means of a heat transfer medium.