CE Marking for Electronic Products: A Practical Guide for PCB and Hardware Development

Bringing an electronic product to the European market involves more than designing a functional PCB and passing a final laboratory test. Manufacturers must determine which European legislation applies to their product, identify the relevant technical requirements and standards, demonstrate conformity, prepare the required technical documentation and, where applicable, affix the CE marking.

For hardware developers, CE compliance should therefore be considered from the beginning of the product development process, not as something that starts when the prototype is already finished.

In this article, we explain the CE compliance process for electronic products and highlight the aspects that are particularly important during PCB and hardware development.

What is CE marking?

The CE marking indicates that a product complies with the applicable EU requirements that govern its market access. It is not a general quality mark and, in many cases, there is no central EU authority that "issues" a CE certificate.

Instead, the manufacturer is responsible for determining the applicable requirements, carrying out or arranging the necessary conformity assessment, preparing the technical documentation and issuing the EU Declaration of Conformity.

Depending on the product and the applicable legislation, a notified body may also be required. However, many electronic products can be assessed by the manufacturer without mandatory third-party certification.

The exact conformity-assessment procedure depends on the product and the legislation that applies to it.

Step 1: Determine which EU legislation applies

The first step is determining which legal requirements apply to the product.

An electronic product can be subject to several pieces of EU legislation at the same time. For example, depending on its design and intended use, an electronic product may need to consider requirements related to:

• Electromagnetic compatibility (EMC)

• Electrical safety

• Radio equipment

• Restriction of hazardous substances (RoHS)

• Machinery or other sector-specific legislation

• Environmental and waste-related requirements

• Other product-specific regulations

The applicable requirements depend on the actual product, its intended use, electrical characteristics, interfaces, operating environment and other design factors.

This is why CE compliance should start with a product compliance assessment rather than immediately booking an EMC test.

Step 2: Identify the applicable standards

Once the applicable legislation has been identified, the next step is to determine which technical standards can be used to demonstrate compliance.

European standards provide technical specifications for products, processes and services. Harmonised standards are particularly important for CE compliance because applying the relevant harmonised standards can provide a recognised way of demonstrating that a product meets the corresponding requirements of EU legislation.

The use of harmonised standards is generally voluntary. However, choosing appropriate standards can provide significant advantages because they give manufacturers a defined technical basis for demonstrating conformity.

For electronic products, this may involve standards covering areas such as:

• EMC emissions

• EMC immunity

• Electrostatic discharge (ESD)

• Electrical fast transients (EFT)

• Surge immunity

• Conducted disturbances

• Radiated disturbances

• Electrical safety

• Insulation and dielectric strength

• Creepage and clearance

• Radio-frequency performance

• Product-specific safety requirements

The correct standards depend on the product category and intended application.

Choosing standards during PCB development

Standards should not be selected only after the PCB has been completed.

For example, EMC requirements can directly influence PCB architecture and layout decisions such as:

• Power-entry filtering

• TVS and surge protection

• Common-mode filtering

• Grounding strategy

• High-current return paths

• Signal return paths

• Layer stack-up

• Differential-pair routing

• Clock and high-speed signal routing

• Shielding

• Connector placement

• Cable interfaces

• Separation of noisy and sensitive circuitry

A PCB designed with EMC requirements in mind is generally much easier to bring through compliance testing than a PCB that is tested for the first time at the end of development.

Step 3: Design the product with compliance in mind

CE compliance is closely connected to engineering decisions.

Consider a typical electronic product with a DC power input, switching regulator, microcontroller, communication interfaces and external connectors.

Even before testing, the design should consider potential sources of electromagnetic emissions and possible paths through which disturbances can enter the product.

Examples include:

Power input

• Reverse-polarity protection

• Overvoltage protection

• Surge protection

• Input filtering

• Appropriate capacitor selection

Switching power supplies

• Controlled switching-node area

• Appropriate current-loop geometry

• Input and output filtering

• Proper grounding

• Minimised parasitic inductance

Digital electronics

• Controlled return paths

• Appropriate rise/fall times

• Clock routing

• Decoupling

• Separation of noisy signals from sensitive circuits

External interfaces

• ESD protection

• Filtering

• Connector grounding

• Cable considerations

• Common-mode noise control

These design measures can significantly affect the eventual EMC test result.

Step 4: Perform conformity assessment

After the applicable requirements and standards have been identified, the manufacturer must demonstrate that the product meets them.

This can involve a combination of:

• Engineering calculations

• Design reviews

• Risk assessments

• Component documentation

• Internal verification

• Laboratory testing

• EMC testing

• Safety testing

• Radio testing, where applicable

• Evaluation against the selected standards

The exact process depends on the applicable EU legislation and conformity-assessment procedure.

For many electronic products, EMC laboratory testing is an important part of the process. However, a laboratory test report alone does not constitute CE marking.

The test report is evidence supporting the manufacturer's conformity assessment.

Step 5: Prepare the technical documentation

A compliant product needs supporting documentation. The technical documentation should demonstrate how the manufacturer has established conformity with the applicable requirements.

Depending on the product, this documentation can include:

• Product description

• Intended use

• Product specifications

• Schematics

• PCB documentation

• Bill of materials

• PCB layout information

• Applicable standards

• Risk assessment

• Design calculations

• Test plans

• EMC test reports

• Safety test reports

• Component documentation

• Critical component declarations

• User instructions

• Labels and markings

• Photographs or product drawings

• EU Declaration of Conformity

The exact contents depend on the applicable legislation and product. Good documentation also provides traceability between the product, its design, the applicable requirements and the evidence used to demonstrate compliance.

Step 6: EU Declaration of Conformity

Once the manufacturer has completed the conformity-assessment process and established that the product complies with all applicable requirements, an EU Declaration of Conformity is prepared.

The Declaration of Conformity is the manufacturer's formal statement that the product meets the applicable EU legislation.

It identifies the product, manufacturer and applicable legislation and standards.

The CE marking can then be affixed where required.

CE marking is not the same as "CE certification"

One of the most common misunderstandings is that a manufacturer simply sends a product to a laboratory and receives a CE certificate. That is not how CE marking works for many products.

A laboratory can perform tests and issue test reports. A notified body may be involved where the applicable legislation requires it.

However, for products subject to manufacturer-based conformity assessment, the manufacturer remains responsible for the conformity of the product and for the Declaration of Conformity.

This distinction is particularly important for companies developing their own electronic products.

Why CE compliance should start at the PCB level

For hardware developers, many compliance problems can be avoided before the first EMC test. A product that fails EMC testing may require changes to:

• PCB layout

• Grounding

• Filtering

• Protection circuitry

• Component selection

• Enclosure

• Cable routing

• Shielding

• Power-supply design

These changes can become expensive when discovered late in the development process. For example, adding a filter after PCB release may require a PCB redesign. Changing the grounding structure can be even more difficult once the mechanical design and PCB have already been finalised.

This is why Design for Compliance is an important part of professional electronic product development.

Pre-compliance testing

One effective approach is to perform pre-compliance testing before the final certification or compliance test. Pre-compliance testing can help identify potential problems early, for example:

• Excessive radiated emissions

• Conducted emissions

• ESD susceptibility

• EFT susceptibility

• Surge susceptibility

• Poor immunity performance

• Noise generated by switching regulators

• Cable-related emissions

Pre-compliance testing does not replace the required conformity assessment or final testing where applicable. Instead, it provides valuable engineering feedback before the product reaches the final compliance stage.

A practical CE workflow for electronic products

For a typical electronic product, the process can be structured as follows:

1. Define the product

→ Intended use→ Operating environment→ Interfaces→ Power supply→ Radio functionality→ User and installation conditions

2. Identify applicable legislation

→ EMC→ Electrical safety→ RED, if applicable→ RoHS→ Product-specific legislation

3. Select applicable standards

→ Product-family standards→ Generic standards where appropriate→ Safety standards→ EMC standards→ Radio standards

4. Design for compliance

→ PCB architecture→ Protection→ Filtering→ Grounding→ Shielding→ Creepage and clearance→ EMC-conscious layout

5. Verification and pre-compliance testing

→ Engineering verification→ EMC pre-compliance→ Safety checks→ Design corrections

6. Final conformity assessment

→ Required laboratory testing→ Evaluation against applicable standards→ Additional assessment where required

7. Technical documentation

→ Schematics→ PCB data→ BOM→ Risk assessment→ Test reports→ Standards→ Product documentation

8. Declaration of Conformity

→ Manufacturer's declaration→ Applicable legislation→ Applicable standards

9. CE marking

→ Product/packaging/documentation marking as required

CE compliance is an engineering process

For electronic products, compliance should not be treated as a final administrative step. The best results come from integrating compliance into the engineering process from the beginning.

Selecting appropriate standards early, designing the PCB with EMC and safety requirements in mind, performing pre-compliance testing and maintaining proper technical documentation can reduce redesigns, testing costs and development delays.

At HiQED, we approach electronic product development with compliance in mind from the hardware and PCB design stage. This includes EMC-conscious PCB design, power and protection circuitry, component selection, design reviews, pre-compliance preparation and support for the documentation required for product compliance.

Important: CE compliance requirements depend on the specific product and applicable legislation. This article provides general engineering information and should not be considered legal advice or a substitute for a product-specific conformity assessment.