Pyrotechnic Trigger Element Manufacturing via Photolithography and PVD

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Solution Overview

Problem

Existing methods for producing electrical triggering elements for pyrotechnic objects, such as detonators or igniters, face issues with unwanted material changes at the edges of the resistance layer due to high laser power during processing, affecting initiation characteristics and being time-consuming and costly.

Innovation Solution

A method involving photolithography to apply a lacquer on the substrate, followed by physical vapor deposition (PVD) to create a precisely defined electrically conductive layer, with subsequent metal plating and selective removal to define the resistor geometry, ensuring precise edges and homogeneous material distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If laser material processing is used to create the shape of the resistive surface, then the edges of the resistive layer can be defined, but unwanted material changes occur at the edges due to high laser power, negatively affecting initiation characteristics

Engineering Contradiction:
Improveedge definition of resistive layerVSAvoidmaterial changes at edges
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The harmful laser processing step is extracted and replaced by a photolithographic approach where a resist mask is applied to define the resistive area geometry, and the PVD process is selectively applied only to the uncovered substrate areas, eliminating laser-induced material changes at edges

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

A photolithographic resist mask is introduced as an intermediary tool to define the geometry of the resistive area. The resist prevents PVD coating in specific areas, allowing precise edge definition without direct laser-material interaction that causes harmful material changes

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If individual processing of each trigger element is performed, then precise control over each component is achieved, but the manufacturing process becomes very time-consuming

Engineering Contradiction:
Improvecontrol over each componentVSAvoidmanufacturing speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

Multiple trigger elements are merged onto a single substrate and processed simultaneously using photolithography and PVD. The entire array of ignition elements can be manufactured in parallel on one substrate, then separated later, dramatically increasing productivity while maintaining precision through the photomask approach

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The substrate is divided into multiple independent ignition element areas, each defined by the photomask pattern. This allows batch processing of multiple elements simultaneously while maintaining individual precision through the mask-defined geometry, resolving the contradiction between individual control and manufacturing speed

Inventive Principle:
Principle #1Segmentation

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 allows for precise definition of resistor edges and geometry, reducing material changes and processing time, enabling mass production while maintaining high initiation characteristics and reducing costs.

Implementation Method 1

a resist is first applied to the substrate photolithographically

Methodology Applied
Scientific EffectPhotolithography: Photography

Implementation Method 2

The resistive layer, made of a metal with high resistivity, is applied to the substrate (e.g., ceramic or glass) using a physical vapor deposition (PVD) process

Methodology Applied
Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 3

a precisely defined area of the resistive strip is covered with resist. The entire substrate surface is then coated with a relatively thick layer of highly conductive metal (e.g., electroplated gold)

Methodology Applied
Scientific EffectElectroplating: Electroplating

Data Source

PatentEP3339798B1Method for producing electric trigger elements for pyrotechnic articles
Publication Date: 2020.09.23 RWS GMBH

AI summary

The invention relates to a method for manufacturing electrical triggering elements for pyrotechnic articles such as detonators or igniters, in which, in a first stage, a) a lacquer is photolithographically applied to a non-electrically conductive substrate, b) a conductive material is applied to the lacquer and substrate in a layer thickness of 0.02 µm to 8.0 µm and with a specific resistance of 0.1 Ω*mm to 5.0 Ω*mm by means of a PVD process, and c) the lacquer is removed from the substrate, and optionally, in a second stage, d) a photolithographic process is carried out again in which a precisely defined area of ​​the resistive strip is covered with photoresist, e) the entire substrate surface is coated with a 0.1 µm to 20 µm thick layer of a metal with a specific resistance of 0.01 Ω*mm to 0.1 Ω*mm, wherein the application of the metal is designed such thatthat in areas where the substrate is bare from the first photolithography process, no metal adheres and f) the varnish is removed again by the second photolithography process.