Flexible Substrate Sealing for Electronic Modules

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Solution Overview

Problem

The existing methods for sealing electronic modules with resin cause damage to the electronic devices and disconnection in the wiring patterns due to the high pressure exerted by the melted resin during the sealing process.

Innovation Solution

A method involving a flexible substrate with a metallic foil wiring pattern, where the metallic foil has a recrystallization or melting temperature lower than the resin molding temperature, and a retention layer with a conductive foundation layer, allowing the substrate to deform and reduce pressure on the electronic device, while maintaining electrical connectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the chassis is filled with melted resin to seal the electronic device, then the sealing is achieved, but the melted resin applies large pressure causing damage to the electronic device and disconnection in the wiring pattern

Engineering Contradiction:

Improvesealing qualityVSAvoidpressure damage to electronic device

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A cushioning layer made of foam material with lower density than the resin is placed between the resin and the electronic device before sealing. This cushioning layer absorbs the pressure from the injected resin, preventing direct transmission of force to the electronic device and wiring pattern, thereby avoiding damage while maintaining effective sealing.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Stability of the object's composition

If a rigid substrate is used to support the electronic device, then structural stability is improved, but the substrate cannot deform to reduce pressure during resin sealing

Engineering Contradiction:

Improvesubstrate structural stabilityVSAvoidpressure transmission to electronic device

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The substrate is designed with flexible characteristics allowing it to deform under resin injection pressure. This flexibility enables the substrate to absorb and distribute the pressure, preventing concentrated force transmission to the electronic device while maintaining overall structural stability during the sealing process.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If the wiring pattern is made of rigid metallic material, then electrical conductivity is ensured, but the wiring pattern is prone to disconnection under resin pressure

Engineering Contradiction:

Improveelectrical conductivityVSAvoidresistance to pressure-induced disconnection

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The wiring pattern is constructed as a composite structure combining metallic foil for electrical conductivity with a flexible substrate material for mechanical resilience. This composite design allows the wiring to maintain electrical function while the flexible substrate component absorbs pressure, preventing disconnection of the wiring pattern during resin sealing.

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

This approach reduces the risk of damage to the electronic device and prevents disconnection in the wiring pattern during resin sealing, improving the reliability and productivity of the electronic module manufacturing process.

Implementation Method 1

the metallic foil is composed of a material having a recrystallization temperature equal to or less than a molding temperature at which the circuit unit is sealed with the electrical insulating resin

Methodology Applied

Scientific EffectRecrystallization: Crystallisation

Implementation Method 2

the metallic foil may be composed of a material having a melting temperature equal to or less than a molding temperature at which the circuit unit is sealed with the electrical insulating resin

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

the substrate has flexibility to be deformable due to a pressure during sealing with the electrical insulating resin

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 4

the circuit-unit forming step solders the electronic device to the wiring pattern

Methodology Applied

Scientific EffectSoldering: Soldering

Data Source

PatentEP3564991B1Method for manufacturing an electronic module

Publication Date: 2023.02.15 TATEYAMA KAGAKU CO LTD

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AI summary

A substrate 12 having flexibility and an electrical insulation property and a circuit unit 15 in which an electronic device 14 is mounted on a wiring pattern 13 formed on at least any one of surfaces of the substrate 12 are provided. A resin body 16 in which the circuit unit 15 is sealed with an electrical insulating resin is provided. The substrate 12 has flexibility to be deformable due to a pressure during sealing with the electrical insulating resin. The substrate 12 is composed of a material having air permeability. The wiring pattern 13 is a metallic foil that enables soldering. The metallic foil is a material having a recrystallization temperature or a melting temperature equal to or less than a molding temperature at which the circuit unit 15 is sealed with the electrical insulating resin. A circuit-unit forming step of forming the circuit unit 15 by mounting the electronic device 14 and a sealing step of sealing the circuit unit 15 with the resin body 16 of the electrical insulating resin are provided.