Recessed Solder Mask for Gas Escape in Centrifugal Pump PCB

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Solution Overview

Problem

Centrifugal pumps often experience defective solder joints due to trapped gases during the soldering process, leading to contact interruptions and laborious manual rework, especially with electronic components having three or more wire connections.

Innovation Solution

The circuit board design features a solder mask that is partially recessed under the electronic component, allowing gases to escape through channels next to the component during soldering, preventing the formation of defective solder joints by ensuring gases do not get trapped between the component and the board.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electronic components are mounted on circuit boards using traditional soldering methods, then electrical connections are established, but gases trapped during soldering cause defective solder joints and contact interruptions

Engineering Contradiction:
Improvesolder joint qualityVSAvoidtrapped gases during soldering
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The circuit board structure is segmented by creating separate channels between the electronic component and the circuit board surface. These channels divide the enclosed space into separate gas escape paths, allowing soldering gases to escape through multiple routes rather than being trapped in a single enclosed space, thereby preventing defective solder joints.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The harmful factor (soldering gases) is extracted from the enclosed space between the electronic component and circuit board by creating channels that lead to the external environment. The channels act as escape routes that remove the gases from the soldering zone, preventing them from causing defects in the solder joints.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If manual rework is performed to fix defective solder joints, then contact interruptions are corrected, but production time is significantly increased

Engineering Contradiction:
Improvecontact reliabilityVSAvoidmanual rework time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The channels are pre-formed in the circuit board structure before the electronic component is mounted. This preliminary preparation creates built-in gas escape routes that prevent soldering defects from occurring in the first place, eliminating the need for subsequent manual rework to fix defective joints.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the circuit board structure is modified to include channels for gas escape, then defective solder joints are prevented, but device complexity increases

Engineering Contradiction:
Improvesolder joint qualityVSAvoidcircuit board structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The channels are created only in specific local areas where gas escape is needed, rather than modifying the entire circuit board structure. This localized approach maintains the simplicity of the overall device while introducing the necessary complexity only where required to prevent soldering defects.

Inventive Principle:
Principle #3Local quality

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

This design significantly reduces the occurrence of defective solder joints and contact interruptions, resulting in more reliable electrical connections and reduced manual rework during production.

Implementation Method 1

the solder mask between the electronic component and the printed circuit board is at least partially recessed and the recessed part extends between at least one and preferably all contact holes to the side of the electronic component, so that a gas can escape from the contact holes into the ambient air

Methodology Applied
Scientific EffectGas escape through recessed solder mask:

Implementation Method 2

the wire leads are connected to the contact holes or traces and soldered to the conductor tracks on the bottom side

Methodology Applied
Scientific EffectSoldering: Soldering

Data Source

PatentEP4006351A1Centrifugal pump with a motor
Publication Date: 2022.06.01 WILO SE
  • EP4006351A1 patent drawingFigure 1
  • EP4006351A1 patent drawingFigure 2
  • EP4006351A1 patent drawing

AI summary

The invention relates to a centrifugal pump (1) with a motor (2), an impeller (3) driven by the motor (2) for pumping a fluid, and a control unit (4) which is configured to control the motor (2), wherein the control unit (4) comprises a printed circuit board (5) with at least one top surface (6) of the printed circuit board (5) having solder mask (7), contact holes (8), conductor tracks provided at least one bottom surface of the printed circuit board (5), and at least one electronic component (9) provided on the top surface (6) having at least three wire connections (10) which are passed through the contact holes (8) and soldered to the conductor tracks on the bottom surface in such a way that the electronic component (9) is in contact with the solder mask (7).and the solder mask (7) between the electronic component and the circuit board (5) is at least partially recessed and the recessed part (11) extends between at least one and preferably all contact holes (8) to the side of the electronic component (9), so that a gas can escape from the contact holes (8) into the ambient air.