Copper Foil Exposure for Electrical Connection in Circuit Modules

Solution Overview

Problem

Conventional modules experience reliability issues due to peeling at the interface between the copper foil and the insulating layer during the division process, leading to reduced electrical connection reliability and increased susceptibility to electromagnetic interference.

Innovation Solution

A module design featuring a circuit board with copper foil exposed on its side surfaces, where the copper foil and metal film are electrically coupled, and the copper foil is embedded in an epoxy layer with strategically positioned exposed parts less than 200 μm wide to enhance adhesion and shielding effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the copper foil is completely embedded in the insulating layer during division, then the structural integrity is maintained, but the electrical connection reliability deteriorates due to peeling at the interface

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidinterface stability between copper foil and insulating layer

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent extracts a portion of the copper foil from the insulating layer to create an exposed part on the side surface. This extracted copper foil portion forms a protrusion that extends from the insulating layer, enabling direct electrical connection between adjacent circuit boards without requiring interface adhesion during division.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The copper foil is pre-positioned to extend beyond the insulating layer before the division process. This preliminary configuration ensures that the electrical connection is already established and does not depend on the integrity of the copper-insulating layer interface during subsequent division operations.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the copper foil is exposed on the side surface for electrical connection, then the electrical connection reliability improves, but the peeling occurrence increases at the interface between copper foil and insulating layer

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidpeeling occurrence

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts a portion of the copper foil from the insulating layer to create an exposed part on the side surface. This extracted copper foil portion forms a protrusion that extends from the insulating layer, enabling direct electrical connection between adjacent circuit boards without requiring interface adhesion during division.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The copper foil has different configurations at different locations: it is embedded in the insulating layer at most areas to maintain interface stability, but exposed at specific side surface areas to provide electrical connection. This local differentiation resolves the contradiction between connection reliability and peeling prevention.

Inventive Principle:

Principle #3Local quality

3Reliability

If the exposed part of copper foil is made wider to improve electrical connection, then the electrical conductivity improves, but the peeling susceptibility increases

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidadhesion strength at interface

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The copper foil has different configurations at different locations: it is embedded in the insulating layer at most areas to maintain interface stability, but exposed at specific side surface areas to provide electrical connection. This local differentiation resolves the contradiction between connection reliability and peeling prevention.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS8946563B2Module with exposed parts of copper foil and process for production thereof

Publication Date: 2015.02.03 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A module including a circuit board including an insulating layer and one or more layers of copper foil embedded in the insulating layer; an electronic component mounted on the circuit board; a sealing part sealing the electronic component on the circuit board; and a metal film covering side surfaces of the circuit board and surfaces of the sealing part. A part of the copper foil is exposed to the side surfaces of the circuit board, an exposed part of the copper foil has a width of less than 200 μm, and the copper foil and the metal film are electrically coupled to each other through the exposed part. Thus, occurrence of blushing, crack, or the like, can be prevented.