Radar PCB Assembly With DC Shorted RF Traces for Explosion Protection

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Solution Overview

Problem

Radar arrangements face challenges in ensuring safe operation and high levels of explosion protection, particularly in explosive atmospheres, where existing designs may not adequately prevent sparks or thermal effects that could ignite such environments.

Innovation Solution

A metal layer with electrical reference potential is arranged between the carrier and high-frequency substrate layers, with through-holes forming a DC short circuit to ensure the line structure and metal layer have the same potential, preventing potential differences and reducing the need for complete encapsulation, thereby enhancing explosion protection without influencing high-frequency signal transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the line structure is completely covered with casting compound to ensure explosion protection, then explosion protection is improved, but the complexity of the device and manufacturing difficulty increase

Engineering Contradiction:
Improveexplosion protectionVSAvoidencapsulation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention applies equipotentiality by connecting the line structure to the metal layer with reference potential through DC short circuits using through-holes. This ensures that no potential difference arises between the line structure and metal layers, eliminating spark risks without requiring complete encapsulation with casting compound, thus reducing device complexity while maintaining explosion protection

Inventive Principle:
Principle #12Equipotentiality

Solution Approach 2:

The invention extracts the essential safety function from complete encapsulation by identifying that only potential difference prevention is needed for explosion protection. By removing the line structure from the encapsulation requirement and addressing its safety through separate DC short circuit connections to the reference potential metal layer, the solution simplifies the overall device structure

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If through-holes are used to connect the line structure to the metal layer for DC short circuit, then explosion protection is improved, but high-frequency signal transmission may be affected

Engineering Contradiction:
Improveexplosion protectionVSAvoidhigh-frequency signal power
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The invention applies dynamics by making the through-hole connection frequency-dependent in its behavior. At DC and low frequencies, the through-holes provide short circuits for safety. At high frequencies, the through-holes naturally become ineffective for signal transmission due to their physical dimensions being small compared to the wavelength, thus preventing high-frequency signal power loss while maintaining DC safety functionality

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention applies local quality by creating different electrical characteristics at different locations and frequencies. The through-holes provide low impedance paths for DC (safety function) but present high impedance to high-frequency signals (preserving signal integrity). This localized differentiation of electrical properties allows simultaneous achievement of explosion protection and signal transmission

Inventive Principle:
Principle #3Local quality

3Strength

If the thickness of the HF substrate is increased to improve mechanical stability, then structural strength is improved, but the attenuation of electromagnetic waves increases

Engineering Contradiction:
Improvemechanical stabilityVSAvoidelectromagnetic wave attenuation
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The invention applies parameter changes by optimizing the HF substrate thickness to a specific range that balances mechanical stability and electromagnetic performance. The thickness is selected based on the operating frequency and permittivity of the substrate material, achieving a compromise where the substrate is thick enough for mechanical support but thin enough to minimize signal attenuation

Inventive Principle:
Principle #35Parameter changes

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 design ensures safe operation by preventing spark formation in explosive atmospheres and improving explosion protection without compromising high-frequency signal transmission, as the through-holes only form a DC short circuit and do not significantly affect the high-frequency signal, allowing for flexible substrate thickness and efficient signal routing.

Implementation Method 1

the line structure is connected to the metal layer in regions via at least one through-hole in such a way that the at least one through-hole forms a DC short circuit so that the line structure and the metal layer have the same potential during operation

Methodology Applied
Scientific EffectDC short circuit: Conduction (electrical)

Implementation Method 2

at least one line structure for guiding the high-frequency signal between the electronic component and the antenna

Methodology Applied
Scientific EffectElectromagnetic signal transmission: Electromagnetic Induction

Implementation Method 3

During operation, the high-frequency signal is radiated outside via the antenna

Methodology Applied
Scientific EffectElectromagnetic radiation: Radar

Data Source

PatentEP4293815A1Radar assembly
Publication Date: 2023.12.20 KROHNE MESSTECHNICK GMBH & CO KG
  • EP4293815A1 patent drawingFigure 1~2
  • EP4293815A1 patent drawingFigure 3~4
  • EP4293815A1 patent drawingFigure 5~6

AI summary

Described and illustrated is a radar arrangement (1) comprising at least one multilayer printed circuit board (2), at least one antenna (3), at least one electronic component (4) for generating and converting a high-frequency signal, and at least one transmission structure (5) for guiding the high-frequency signal between the electronic component (4) and the antenna (3), wherein the multilayer printed circuit board (2) has at least one first layer (6) made of a substrate material and at least one second layer (7) made of an RF substrate, wherein the RF substrate has a component side (8), and wherein at least the electronic component (4) for generating and converting the high-frequency signal and the antenna (3) are arranged on the component side (8), and wherein the at least one transmission structure (5) for guiding the high-frequency signal is arranged at least partially on the component side (5).wherein the component side (8) is encapsulated at least in the area of ​​the electronic component (4) for generating and converting a high-frequency signal. The problem of specifying a radar arrangement that ensures particularly safe operation and particularly high explosion protection is solved by arranging a metal layer (9) having an electrical reference potential between the first layer (6) and the second layer (7) and by connecting the conductor structure (5) to the metal layer (9) in certain areas via at least one via (10) such that the at least one via (10) forms a DC short circuit, so that the conductor structure (5) and the metal layer (9) have the same potential during operation.