Wearable Device Strap Manufacturing With Caged PCB Encapsulation

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Solution Overview

Problem

Existing wearable electronic devices face challenges in accommodating internal components within a compact, flexible, and comfortable strap design, which can cause deformation, discomfort, and aesthetic issues, while also requiring radio transparency and protection from shock and water ingress.

Innovation Solution

A method of manufacturing a strap that encapsulates electronics using a flexible material, employing a cage to position and protect PCBs, and injecting a wet structural component to form a seamless, radio-transparent enclosure, ensuring consistent spacing and using vents for vacuum application to prevent blemishes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the strap is made of harder materials to protect electronic components, then protection from shock and deformation is improved, but comfort and flexibility deteriorate

Engineering Contradiction:
Improveprotection from shockVSAvoidflexibility
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent employs a composite structure combining a rigid mould (for structural integrity and protection) with a flexible material (such as silicone rubber or polyurethane) that encapsulates the electronics. This composite approach allows the strap to provide shock protection while maintaining flexibility and comfort for wearable application.

Inventive Principle:
Principle #40Composite materials

2Volume of stationary object

If the volume of electronics consumes much of the strap length, then component housing capacity is improved, but adjustability for different wrist sizes deteriorates

Engineering Contradiction:
Improveelectronics housing capacityVSAvoidstrap length adjustability
Core Design Contradiction:
Volume of stationary objectVSAdaptability or versatility

Solution Approach 1:

The patent segments the strap into distinct functional zones: an upper portion that remains free for adjustment mechanisms (buckle, slide, or magnetic connector) and a lower portion that houses the electronics. This segmentation allows the electronics to occupy necessary volume while preserving adjustability features in the upper section for different wrist sizes.

Inventive Principle:
Principle #1Segmentation

3Length of moving object

If the PCB is positioned closely to the mould to reduce strap thickness, then strap profile is improved, but risk of PCB protrusion and blemishes increases

Engineering Contradiction:
Improvestrap thicknessVSAvoidPCB positioning accuracy
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent introduces a cage structure as an intermediary element between the PCB and the mould. The cage positions the PCB at an optimal distance from the mould wall, preventing protrusion while maintaining a sleek profile. It also serves as a reference feature for the insert tool, ensuring precise positioning and preventing blemishes during the injection process.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Device complexity

If a single opening is used for both PCB insertion and material injection, then device complexity is reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improvenumber of openingsVSAvoidcomponent positioning precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent designs a single multi-functional opening that serves both as an insertion path for the PCB/cage assembly and as an injection port for the flexible material. The cage structure with its integrated insert tool provides precise positioning features that enable accurate component placement through this single opening, maintaining manufacturing precision while simplifying the overall device structure.

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

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 method provides a comfortable, aesthetically pleasing, and functional wearable device that protects electronics from damage and water ingress, while allowing for adjustable fit and radio signal transmission.

Implementation Method 1

the mould comprises at least one vent which connects to a vacuum generator for generating a vacuum which is filled by said wet applied structural component

Methodology Applied
Scientific EffectVacuum: Vacuum

Data Source

PatentEP4389387B1A method of manufacturing a strap for a wearable device
Publication Date: 2025.10.08 SENTURION INTERNATIONAL LTD
  • EP4389387B1 patent drawingFigure 1A~1B
  • EP4389387B1 patent drawingFigure 2
  • EP4389387B1 patent drawingFigure 3

AI summary

A method of manufacturing a wearable device comprising a printed circuit board (PCB) on which is mounted electronic components, the method includes providing a mould attaching the PCB to a cage, the cage comprising a cage body and at least one hole, inserting said PCB into the mould; arresting the PCB relative to the mould by inserting an insert tool into the mould and attaching the insert tool to said at least one hole, injecting a wet applied structural component into said mould and removing said mould.