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Methods to Determine Halogen-Free PCBs

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Halogen PCB Circuit Boards Assembly

In the realm of printed circuit boards (PCBs), the shift towards halogen-free compositions has become increasingly pivotal. As concerns regarding the environmental and health impacts of halogenated flame retardants persist, the demand for halogen-free PCBs continues to escalate. To ensure the reliability and compliance of these PCBs, employing accurate and effective methods for their determination is imperative. This article delves into the various techniques and approaches utilized in the analysis of halogen-free PCBs, shedding light on the advancements and insights in this critical area of PCB manufacturing.

Background on Halogen-Free PCBs

Halogen-free printed circuit boards (PCBs) are circuit boards that do not incorporate halogenated flame retardants, such as polybrominated diphenyl ethers (PBDEs) or polychlorinated biphenyls (PCBs). These flame retardants have historically been utilized in PCBs to mitigate fire hazards. However, their persistent organic pollutant (POP) characteristics, which can lead to bioaccumulation and pose significant risks to both human health and the environment, have prompted a shift towards halogen-free PCBs.

The importance of halogen-free PCBs has been underscored by the increasing recognition of the environmental and health dangers associated with halogenated flame retardants. Regulatory frameworks in many countries and regions have been established to restrict or prohibit the use of these compounds in PCBs.

Various methodologies exist to ascertain the halogen-free status of a PCB. These methodologies typically involve extracting halogens from the PCB and then subjecting the extract to analytical techniques such as ion chromatography or X-ray fluorescence spectroscopy.

The adoption of halogen-free PCBs offers multiple advantages, including a diminished environmental footprint, enhanced human health and safety, and compliance with regulatory mandates. Numerous PCB manufacturers now provide halogen-free PCBs as a viable substitute for conventional PCBs, incorporating alternative flame retardants such as phosphorus-based or nitrogen-based options.

The transition to halogen-free PCBs represents a pivotal stride towards diminishing the environmental and health repercussions associated with electronic waste.

Regulatory Requirements for Halogen-Free PCBs

The regulatory landscape surrounding halogen-free printed circuit boards (PCBs) is in a state of constant evolution, with an increasing number of countries and regions enacting restrictions on the use of halogenated flame retardants. Key regulatory requirements for halogen-free PCBs include international standards such as IEC 61249-2-21, which sets the maximum allowable halogen content at 1500 ppm for chlorine and bromine, and 900 ppm for iodine in halogen-free PCBs.

Furthermore, the IPC-4101 standard outlines performance requirements and test methods for halogen-free and low-halogen printed boards, defining halogen-free PCBs as those containing less than 1500 ppm of chlorine and bromine, and less than 900 ppm of iodine. The EU RoHS Directive, a pivotal regulation in the European Union, restricts the use of hazardous substances in electrical and electronic equipment, including halogenated flame retardants, mandating that PCBs marketed in the EU contain less than 0.1% (1000 ppm) of bromine and chlorine.

In addition to these international and regional regulations, many countries have developed their own national standards for halogen-free PCBs. For instance, China’s mandatory standard (GB/T 29741-2013) limits the halogen content of PCBs to 1500 ppm for chlorine and bromine, and 900 ppm for iodine.

It is essential for PCB manufacturers and end-users to be well-informed about the regulatory requirements for halogen-free PCBs within their respective jurisdictions. By adhering to these regulations, manufacturers can ensure that their products meet the necessary safety and environmental standards. It is crucial to note that regulatory requirements for halogen-free PCBs are subject to change, underscoring the importance of staying abreast of the latest regulatory developments to maintain compliance.

Methods for Determining Halogen Content in PCB

There are several methods available to determine the halogen content in printed circuit boards (PCBs), which are crucial for ensuring compliance with regulatory requirements for halogen-free PCBs. Some common methods for analyzing halogen content in PCBs include:

1.Ion Chromatography (IC):

Ion chromatography is a widely used analytical technique for determining the halogen content in PCBs. This method involves separating and quantifying halogen ions using a chromatographic column and a conductivity detector. IC is a sensitive and accurate method for quantifying halogens such as chlorine, bromine, and fluorine in PCB samples.

2.X-ray Fluorescence (XRF) Spectroscopy:

XRF spectroscopy is a non-destructive analytical technique that can be used to determine the halogen content in PCBs. XRF instruments emit X-rays that interact with the sample, producing characteristic fluorescent X-rays that can be used to quantify the halogen content. XRF spectroscopy is a rapid and convenient method for analyzing halogens in PCBs.

3.Fourier Transform Infrared (FTIR) Spectroscopy:

FTIR spectroscopy is another method that can be used to determine the halogen content in PCBs. This technique involves measuring the absorption of infrared radiation by the sample, allowing for the identification and quantification of halogen-containing compounds. FTIR spectroscopy is a versatile method that can provide valuable information about the chemical composition of PCBs.

4.Combustion Ion Chromatography (CIC):

Combustion ion chromatography is a specialized technique used for analyzing halogen content in PCBs by combusting the sample and analyzing the resulting combustion gases using ion chromatography. This method is particularly useful for determining the total halogen content in PCB samples.

5.Inductively Coupled Plasma Mass Spectrometry (ICP-MS):

ICP-MS is a sensitive analytical technique that can be used to determine trace levels of halogens in PCB samples. This method involves ionizing the sample in an inductively coupled plasma source and analyzing the resulting ions using mass spectrometry. ICP-MS is a powerful tool for quantifying halogen content in PCBs at low concentrations.

These methods offer a range of options for determining the halogen content in printed circuit boards, enabling manufacturers to ensure compliance with regulatory requirements for halogen-free PCBs. The selection of the most appropriate method may depend on factors such as the sensitivity, accuracy, and sample size requirements of the analysis.

Benefits of Using Halogen-Free PCBs

Utilizing halogen-free printed circuit boards (PCBs) offers a multitude of advantages, including:

1.Environmental Impact Reduction:

Halogenated flame retardants, recognized as persistent organic pollutants (POPs), possess the potential to bioaccumulate and present hazards to both human health and the environment. Halogen-free PCBs, devoid of these detrimental chemicals, contribute to a diminished environmental impact.

2.Enhancement of Human Health and Safety:

Halogenated flame retardants have been associated with various health issues, such as thyroid malfunctions, developmental disorders, and cancer. The absence of these substances in halogen-free PCBs ensures a safer environment for human health.

3.Regulatory Compliance:

Numerous countries and regions have enforced regulations limiting or prohibiting the use of halogenated flame retardants in PCBs. Opting for halogen-free PCBs ensures compliance with these regulations, safeguarding manufacturers against legal consequences and reputational harm.

4.Enhanced Product Quality:

Research indicates that halogen-free PCBs exhibit superior electrical properties compared to their halogenated counterparts. This translates to improved product performance and reliability.

5.Cost Savings in Manufacturing:

In certain instances, manufacturing halogen-free PCBs may prove to be more cost-effective than producing PCBs containing halogenated flame retardants. The expense and specialized handling requirements associated with halogenated flame retardants can be mitigated by opting for halogen-free alternatives.

Ultimately, the adoption of halogen-free PCBs delivers a host of benefits, including environmental friendliness, improved human health and safety, regulatory compliance, enhanced product quality, and potential cost savings in manufacturing processes. As awareness of the adverse environmental and health impacts of halogenated flame retardants escalates, the demand for halogen-free PCBs is anticipated to rise. Manufacturers embracing halogen-free PCBs position themselves favorably to meet evolving customer preferences and adhere to forthcoming regulatory mandates.

Case Study

1.Analysis of Halogen-Free PCBs in Electronic Assemblies

A prominent electronics manufacturer sought to assess the halogen content of the printed circuit boards (PCBs) utilized in their products due to concerns regarding the environmental and health implications of halogenated flame retardants. With a commitment to ensuring regulatory compliance, the manufacturer submitted samples of their PCBs to an accredited independent laboratory for analysis. Employing ion chromatography (IC), the laboratory conducted comprehensive testing to determine the halogen content of the PCBs.

The results obtained from the analysis indicated that all tested PCBs contained levels below the specified thresholds, with less than 1500 ppm of chlorine and bromine, and less than 900 ppm of iodine. These findings demonstrated that the PCBs met the stringent requirements for halogen-free PCBs as outlined in industry standards such as IEC 61249-2-21 and IPC-4101. This successful analysis provided the manufacturer with the assurance that their products complied with the necessary regulatory standards for halogen content in PCBs.

 2: Validation of a Combustion-Ion Chromatography Method

A research laboratory sought to establish the validity of a combustion-ion chromatography (CIC) method for assessing the halogen content in printed circuit boards (PCBs). To validate the method, the laboratory opted to utilize a certified reference material (CRM).

By meticulously preparing a series of CRM samples and subjecting them to analysis through the CIC method, the laboratory was able to ascertain the accuracy and precision of the technique. The results revealed that the CIC method consistently delivered halogen content measurements within a 5% margin of the certified values for the CRM samples.

Furthermore, the laboratory extended the application of the CIC method to analyze a diverse array of PCB samples. The outcomes of these analyses demonstrated the method’s capability to reliably and accurately determine the halogen content in PCBs across a broad spectrum of halogen concentrations. This successful validation underscored the effectiveness and versatility of the CIC method for assessing halogen content in PCBs.


The analysis of halogen-free PCBs plays a crucial role in promoting sustainability, ensuring product safety, and complying with regulatory standards. By leveraging a diverse range of analytical methods, manufacturers can confidently verify the halogen content in PCBs and align with industry best practices. As the landscape of PCB production evolves, the adoption of robust analytical techniques for assessing halogen-free compositions will be key to driving innovation, enhancing quality, and meeting the expectations of environmentally-conscious consumers.

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