However, most of the halogens found in fluxes are covalently bonded so the test won’t detect them. For example, the IPC specifies tests for detecting halogens in PCBs, and these tests generally detect ionically bonded halogens.
Now why is “halogen free” in quotations? It’s because meeting the standard doesn’t necessarily guarantee your board has no halogens in it.
The IEC defines halogen free as < 900 ppm of chlorine and bromine and < 1500 ppm total halogens, while the RoHS has its own limits. Like with any standard “halogen free” specific limits that are set by various organizations. Like the RoHS lead free requirements, halogen free standards require CMs to use new materials and manufacturing methods. Now that we’ve reviewed the main sources of halogens in circuits, what should we do about it? Halogen Free PCBs BFRs are used in PCB laminates to reduce the risk of the board catching fire. Chlorinated solvents can be used to clean PCBs during the manufacturing process. So where exactly are halogens found in a circuit board?Īs you already know, PVC is used not only for piping, but also wire insulation, so that can be a source of halogens. This is the main problem with halogens in electronics they can be released at the end of a PCB’s lifecycle. If you were to burn that pipe and inhale the chlorine gas that is released when the plastic breaks down, that might be a different story. Halogens are obviously not dangerous in every form or concentration, and it’s unlikely that you’ve ever experienced health problems from holding a PVC pipe or drinking tap water. Halogens are usually found in brominated flame retardants (BFRs), chlorinated solvents, and polyvinyl chloride (PVC). If you asked most designers where halogens are found in a PCB, it is doubtful they could tell you. Some replacements substances require special design considerations that you’ll need to take into account as well. You’ll also need to decide exactly how free of halogens you want your circuits to be.
In order to create a “halogen free PCB,” you’ll need to replace some materials or reduce their use on your board. In response to this health risk the IEC developed a halogen free standard for PCB manufacturers, but what exactly is a halogen free PCB? Electronics contain a few specific materials that contain the highest concentrations of halogens. Some of our more cautious citizens scorn fluorinated or chlorinated water because they’re afraid the government is using it for “mind control.” Conspiracy theories aside, it turns out fluorine and chlorine can have adverse health effects in certain forms and are often found in circuit boards. People have long questioned the presence of some chemicals in our daily lives.
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