Four Common RoHS Concerns Relating to PCB Assembly
Screaming Circuits are the experts in protoype pcb assembly - as fast as 24-hour turn times. We can put just about any part, from tiny 0201 passives up to 1,700+ ball BGAs, on just about any board. And we can assemble your prototype with traditional lead-based solder or in a complete lead-free process.
Base Circuit Board: Industry research has found that the substrate and board finish used on lead-free boards may need to be different than for circuit boards using lead. If sending us (or any assembly house) a kit, make sure to have your boards fabbed for lead-free / RoHS compliance.
It's not just the lead. Standard FR4 material will sometimes delaminate during the lead-free reflow process due to the higher temperature profiles required. The problem can be exacerbated if the board has to make multiple passes through the oven for double sided smt or rework. You may need to be even more cautious with boards that are primarily through-hole. Early Industry feedback suggests that wave soldering is more likely to cause delamination problems than a properly profiled reflow oven.
When ordering pc boards, don’t just ask for a lead-free finish. Make sure the fab house uses materials that can withstand the additional heat and can make multiple passes through processing without problems and specify RoHS compliant boards.
Components: You must verify that all your components meet RoHS standards and do not contain any of the banned substances. Your Bill-of-Materials must specify only RoHS compliant parts and the components in your kit must all meet lead-free and RoHS standards.
Again, it is more than just the lead and other banned substances. The components must also be able to withstand the higher temperatures required in manufacturing. Most standard components will be fine, but some MEMs parts, switches, membranes, LEDs and others may not be able to survive the extra 50 degrees C required. Some can survive the temperatures, but only just barely. Make a note of any components that are heat sensitive, even if RoHS compliant, when you deliver the parts to us (or another assembly house).
Moisture Sensitivity: Many components will, over time, absorb small amounts of moisture. RoHS compliant storage packaging will inhibit this and will list an expiration date. If the protective package is past the expiration date or the packaging has been opened, the part may be destroyed during reflow due to the rapidly expanding water vapor. Typically, such a failure would be seen as a crack on the side of the part.
Opened or moisture-expired parts may still be used on your prototype, but they will need to be baked at the assembly house to slowly remove the excess moisture. When confirming the integrity of the moisture protective packaging, we (or any assembly house) may determine that components need to be baked prior to assembly. If parts need to be baked to remove moisture, it takes an additional 72 hours (at Screaming Circuits) for baking. The assembly does not start until the components are baked. (Screaming Circuits will contact you if we determine your components need to be baked.)
- Ball Grid Arrays: BGAs already contain solder (the solder balls). The BGA solder balls MUST match the type of assembly. While many components will work, even if they take the board out of compliance, BGA attachment may fail completely if you attempt to solder a lead-based solder ball BGA at lead-free reflow temperatures or vice. versa.
Learn more about the RoHS/Lead-Free StandardsQuote and Order your RoHS / lead-free assembly here - Prototypes assembled in as little as 24-hours with or without lead.