In recent times, using safe resources for the safety of the people and the environment has become a priority for several electronic manufacturers all over the world. The Restriction of Hazardous Substances, abbreviated as RoHS, is one prominent standard enacted by the European Union countries to restrict the use of harmful materials in the circuit board assembly. Some of the restricted materials include lead, hexavalent chromium, polybrominated diphenylether, Butyl Benzyl Phthalate (BBP), Bis (2-Ethylhexyl) Phthalate (DEHP), and many more. Among these, lead is a toxic metal, and hence there is an increased demand for using lead-free materials for PCBs among other devices. However, there are certain challenges when using lead-free materials. In this post, we will discuss the challenges OEMs face in making a lead-free PCBs assembly.
What Are the Common Challenges for RoHS or Lead-Free PCB Manufacturing?
Due to the varying complexity of each circuit board design, there are many chances of PCB failure or issues which could arise if proper care is not taken. With a deep understanding of the manufacturing process and knowledge, these issues can be resolved. Here is the list of some common challenges OEMs face during RoHS compliant PCB assembly.
- The Base of the Printed Circuit Board: The substrate has a huge influence on the circuit board in terms of withstanding voltage, dielectric constant, insulation resistance, and many other aspects. Thus, the substrate and finishing of lead-free PCBs should be separated from the conventional circuit board with lead-based board assembly. Lead and prohibited components are not the only reasons. The lead-free reflow process demands high temperatures, therefore the FR4 material is divided into several layers. If PCB rework is required, then there could be heat- or temperature-related issues as the board will be heated several times. A lead-free finish shouldn’t be the only requirement for consideration. It is important to ensure that the OEM uses high-temperature tolerance materials and can be processed multiple times with RoHS compliance.
- RoHS Compliant Components: As mentioned earlier, the lead-free surface finish demands a high melting temperature. Thus, the verification of RoHS compliance of required components is important. Also, one needs to be sure that there are no prohibited materials. Check all the aspects such as the working of switches, components, and so on, as in some situations where components work fine, certain switches or MEMS and LED components may be unable to perform, especially in the higher temperature range. The good part is RoHS compliant components have the temperature ratings mentioned on then which ensures their functionality even at the higher range.
- Moisture Sensitive Components: All the lead-free surface finishes are moisture sensitive. Thus, the components coated with them are provided with a moisture-protective package with an expiry date printed on it. If OEMs continue using an expired component, then there are possibilities of it being damaged due to water vapor. Components with opened packaging or passed expiry dates can be used for RoHS PCB prototyping; but, they would require to be heated to remove the moisture inside.
- Ball Grid Array (BGA) Solder: Ball grid array comes with solder joints. Sometimes, it is difficult for BGA metallic solder balls to be matched with lead-free assembly type. Despite being non-compliant, many components work fine. But, BGA will fail if non-lead-free solder balls are exposed to reflow, lead-free temperature.
The above-mentioned points are a few challenges related to the making of RoHS-compliant PCBs. Perhaps, an experienced RoHS PCB manufacturer like Rigiflex can educate you more about the lead-free PCBs. Our highly-experienced and skilled experts work closely with clients to understand their requirements and assist you on the choice of the right surface finish.