Substrate Flux Coating Segmentation for Conduction Reliability

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Solution Overview

Problem

In integrated electric compressors for vehicle-mounted air conditioners, flux used for soldering can flow out of designated areas, causing conduction failures by preventing electrical connection between the circuit substrate and the housing.

Innovation Solution

A substrate configuration with a flux coating portion, a conductive conduction portion separated from the flux coating, and a silk portion disposed between the flux coating and conduction portions to inhibit flux movement, with the conduction portion surrounding fixing holes to ensure stable electrical connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If flux is coated to improve solder fluidity, then soldering quality is improved, but flux may flow out to conduction portions causing conduction failures

Engineering Contradiction:

Improvesoldering qualityVSAvoidconduction reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The substrate surface is segmented into distinct functional zones: flux coating portions for soldering, resist portions for isolation, and conduction portions for electrical connection. This spatial segmentation prevents flux from flowing onto conduction portions while maintaining soldering quality in designated areas.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different surface regions are given different properties: flux coating portions have properties that promote solder fluidity, resist portions have properties that repel or block flux, and conduction portions maintain electrical conductivity. This local differentiation allows flux to be applied where needed without contaminating conduction paths.

Inventive Principle:

Principle #3Local quality

2Area of stationary object

If conduction portion is disposed close to flux coating portion for compact design, then space utilization is improved, but flux flow-out risk increases

Engineering Contradiction:

Improvespace utilizationVSAvoidflux contamination risk

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

A resist portion is introduced as an intermediary element between the flux coating portion and the conduction portion. This resist portion acts as a barrier that prevents flux from flowing from the flux coating area to the conduction area, enabling compact layout without increasing flux contamination risk.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The problem is solved by adding a dimensional barrier (the resist portion extending in the vertical direction or creating a physical barrier) rather than relying solely on horizontal distance. This allows close proximity in the plan view while maintaining protection through a third-dimensional barrier.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS10492303B2Substrate, electric compressor, and air conditioner

Publication Date: 2019.11.26 MITSUBISHI HEAVY IND THERMAL SYST

AI summary

A substrate includes a substrate body, a flux coating portion which is coated with flux promoting solder fluidity on a surface of the substrate body, a conduction portion which is disposed on the surface of the substrate body to be separated from the flux coating portion and is conductive, and a silk portion which is disposed between the flux coating portion and the conduction portion on the surface of the substrate body and is provided by silk printing.