Electronic Sub-Assembly Carrier Layer Thermal Expansion Matching

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Solution Overview

Problem

Existing electronic sub-assemblies face reliability issues due to differences in thermal expansion coefficients between substrates and mounted components, leading to dimensional instability and reduced lifespan during temperature changes.

Innovation Solution

A carrier layer with a low coefficient of thermal expansion, such as iron-nickel alloys or copper-molybdenum alloys, is used to match the thermal expansion of electronic components, combined with adjustable layer thicknesses and materials to achieve precise thermal and electrical characteristics, enhancing dimensional stability and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional substrate material is used for the carrier layer, then electrical conductivity and ease of manufacture are improved, but dimensional stability during temperature changes deteriorates due to mismatched thermal expansion coefficients

Engineering Contradiction:

Improvedimensional stabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies composite materials by combining a base substrate layer with a specialized coating layer (such as Invar or other low thermal expansion materials) to create a carrier layer with tailored thermal expansion properties. This composite structure allows the carrier to match the thermal expansion coefficient of mounted electronic components, ensuring dimensional stability during temperature changes while maintaining manufacturability through established coating techniques.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the thermal expansion parameter of the carrier layer by selecting and applying specific coating materials with known thermal expansion characteristics. By adjusting the material composition and thickness of the coating layer, the overall thermal expansion coefficient of the carrier can be precisely tuned to match that of the electronic components, thereby improving reliability without fundamentally changing the manufacturing process.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a carrier layer with matched thermal expansion coefficient is used, then reliability is improved, but material selection and process complexity increase

Engineering Contradiction:

ImprovelifespanVSAvoidmaterial selection complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent systematically addresses material selection complexity by focusing on specific parameter ranges for thermal expansion coefficients. Rather than considering all possible materials, the invention identifies and applies coating materials with thermal expansion coefficients within a specific range that matches common electronic components. This parameter-based approach simplifies material selection while ensuring reliability and extended lifespan.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If low thermal expansion materials are used for the carrier layer, then dimensional stability is improved, but thermal and electrical conductivity may deteriorate

Engineering Contradiction:

Improvedimensional stabilityVSAvoidthermal conductivity

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent resolves the conductivity issue by creating a composite carrier layer structure where a thin coating of low thermal expansion material (such as Invar) is applied over or integrated with a base layer that provides adequate thermal and electrical conductivity. This composite approach allows the low thermal expansion coating to provide dimensional stability while the underlying conductive materials maintain necessary thermal and electrical pathways for component operation.

Inventive Principle:

Principle #40Composite materials

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 solution provides a cost-effective and reliable electronic sub-assembly with improved thermal and electrical performance, increased lifespan, and enhanced reliability by matching the thermal expansion of the carrier layer with the component, allowing for high-performance operation.

Implementation Method 1

the coefficient of thermal expansion of which is adjusted to that of the electronic component (e.g. a chip) to be mounted

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

achieved through material selection and layering techniques like plating and galvanic deposition

Methodology Applied

Scientific EffectGalvanic deposition: Electrodeposition

Data Source

PatentUS9913378B2Electronic sub-assembly, a method for manufacturing the same, and a printed circuit board with electronic sub-assembly

Publication Date: 2018.03.06 SCHWEIZER ELECTRONIC AG(DE)

AI summary

Electronic sub-assembly comprising a carrier layer and a mounting area with at least one electronic component, wherein the carrier layer has at least in portions a material with a low coefficient of thermal expansion to adjust the coefficient of thermal expansion of the carrier layer, and wherein at least one compensation layer is provided on the carrier layer adjacent to the installation area, on which compensation layer an electrically insulating, thermally conductive layer and at least one electrically conductive layer are provided.