Folded Multilayer Substrate Assembly Without Through-Holes

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Solution Overview

Problem

The manufacturing of multilayer substrates is costly due to the need for through-holes and external connecting wires, which require accurate positioning and repeated common steps, increasing production expenses.

Innovation Solution

A method involving superposing a cover sheet on a base material sheet with conductive wiring, folding and fixing them together using a thermoplastic resin, and mounting electronic components through holes in the cover sheet, eliminating the need for through-holes and external wires.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If through-holes are drilled and metal layers are plated to achieve electrical continuity between substrates, then electrical connectivity is ensured, but manufacturing cost increases due to additional processing steps

Engineering Contradiction:
Improveelectrical continuityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the through-hole drilling and metal plating steps from the manufacturing process. Instead of creating physical through-holes to achieve electrical continuity, the invention uses a lamination process where conductive patterns are directly formed on the substrate surfaces and connected through adhesive layers, thereby removing the costly and time-consuming through-hole processing steps while maintaining electrical connectivity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical drilling and plating system with a thermal lamination system. Conductive patterns are formed by laminating substrates with conductive adhesive layers under heat and pressure, substituting the mechanical through-hole creation process with a thermal bonding process that achieves the same electrical continuity function more efficiently

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If accurate positioning of wiring and substrates is performed to ensure electrical continuity through through-holes, then electrical connectivity is achieved, but manufacturing effort and cost increase

Engineering Contradiction:
Improveelectrical continuityVSAvoidpositioning effort
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-forming conductive patterns on substrate surfaces before lamination. The conductive adhesive layers are prepared in advance with predetermined patterns, and substrates are positioned based on these pre-formed patterns rather than requiring precise through-hole alignment, thereby reducing positioning effort and time

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent merges the positioning function with the conductive pattern design. By integrating the conductive adhesive layer positioning marks with the actual conductive patterns, the invention eliminates the need for separate positioning procedures, reducing manufacturing effort while ensuring accurate electrical connectivity

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If common steps such as circuit formation and gold plating are executed separately for each substrate, then substrate quality is maintained, but manufacturing cost increases due to repeated processing

Engineering Contradiction:
Improvesubstrate qualityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges multiple substrate processing steps into a single lamination operation. Instead of separately forming circuits and applying gold plating to each substrate, the invention performs circuit formation through conductive adhesive patterns and connects multiple substrates simultaneously in one lamination process, thereby maintaining substrate quality while reducing manufacturing cost through process integration

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The conductive adhesive layer serves multiple functions simultaneously: it acts as the conductive pattern, the bonding agent for lamination, and the positioning reference. This multi-functionality eliminates the need for separate circuit formation and bonding steps for each substrate, reducing repeated processing while maintaining connection reliability

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Adaptability or versatility

If cover sheet and copper foil are laminated sequentially to increase layer count, then substrate functionality is enhanced, but manufacturing cost increases due to repeated common steps

Engineering Contradiction:
Improvesubstrate functionalityVSAvoidmanufacturing cost
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges the lamination of cover sheets, copper foils, and substrates into a single multi-layer lamination process. Instead of sequentially laminating each layer separately with repeated circuit formation steps, the invention performs all lamination operations simultaneously using conductive adhesive patterns, thereby enhancing substrate functionality while reducing manufacturing cost through process consolidation

Inventive Principle:
Principle #5Merging (Combining)

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 method reduces manufacturing costs by omitting through-hole and external wire production steps, allows for various substrate shapes, and protects wiring with the cover sheet, preventing breakage and ensuring accurate electrical continuity.

Implementation Method 1

fixing the base material sheet and the cover sheet adjacent to each other by heating the folded base material sheet and cover sheet to melt at least a part of the cover sheet, and then cooling and curing the base material sheet and the cover sheet

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

heating the folded base material sheet and cover sheet to melt at least a part of the cover sheet, and then cooling and curing the base material sheet and the cover sheet

Methodology Applied
Scientific EffectThermal bonding:

Data Source

PatentEP4661605A1Method for manufacturing multilayer substrate
Publication Date: 2025.12.10 FUTURE TECH CO LTD
  • EP4661605A1 patent drawingFigure 1
  • EP4661605A1 patent drawingFigure 2
  • EP4661605A1 patent drawingFigure 3

AI summary

Provided is a multilayer substrate manufacturing technology that enables manufacturing a multilayer substrate at low cost. First, a cover sheet (2) is superposed on a base material sheet (1) having the same shape and size as a shape and a size of the cover sheet. Wiring (11) is provided on one surface of the base material sheet (1). A hole (21) is made in the cover sheet (2) at a position through which an electronic component is to be mounted to the base material sheet (1) later. The superposed base material sheet (1) and cover sheet (2) are then folded so that the hole (21) is exposed to an outside. The electronic component is inserted into the hole (21), and the electronic component is mounted in continuity with the wiring (11) of the base material sheet (1).