Lead Free PCBs

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What is the lead free PCB

Lead-Free PCB Materials and Process

The solder joint of HASL lead-free is 34℃ higher than that of with lead. Therefore, PCB manufacturers have to make some changes in equipment, raw materials, technology, testing and other aspects to meet the requirements of lead-free welding.

The key point of lead-free PCB is the selection of lead-free base material. We should study the heat resistance, CAF resistance and machinability to choose the base material suitable for us and meeting the requirements of lead-free.

The temperature required for lead-free soldering to reach solder joints has increased dramatically, it is most important to use the base material with high decomposition temperature resin, or the heat resistance of CCL mainly depends on the thermal decomposition temperature of the resin. Therefore, it is not enough to only use the base material with high Tg and Z-CTE, which not only increases the production cost but also can't improve the heat resistance. IPC-4101c stipulates that the Td value of lead-free base material should be greater than or equal to 325℃. PCBONLINE has carried out relevant experiments. Under the same Tg and Z-CTE conditions, after the T260 test, the delamination time of the base material with Td at 350℃ lags behind the base material with Td at 320℃ by 10s. Therefore, it is better to choose the lead-free base material with Td value greater than 350℃ in actual production. Only by increasing the thermal decomposition temperature of resin in CCL can the thermal reliability of lead-free soldering PCB be guaranteed. The following is the commonly used material comparison table used in PCBONLINE.

Brand TYPE Tg(DSC ℃) Td(℃)
Nelco N4000 210 350
Isola 370HR 180 340
Isola IS410 180 350
ITEQ IT158 150 340
ITEQ IT180 180 350
ShengYi S1000-2 180 345
NanYA NP-180 180 350
TUC TU-768 180 350
VENTEC VT-47 170 340
Lead-free base material have different machinability from with lead base material. For example, in laminating process, the Tg of lead-free base material will be higher, and the curing time will be longer. If the curing is not complete, the secondary curing will occur in the subsequent PCB processes and production, which will lead to serious expansion and shrinkage of the board size. In machining processes, the lead-free base material are harder and more brittle, PCBONLINE reduces tool rotation and cutting speed to prevent board splitting. In plug hole process, PCBONLINE will consider whether the heat resistance of plug hole ink is reliable, whether its Tg, CTE and other characteristics are suitable for lead-free base material, etc.

Lead Free PCB Assembly

At present, the lead-free development of passive components is progressing rapidly. In the global lead-free movement catalyzed by European Union laws and regulations, passive component suppliers leading semiconductor manufacturers to lead-free products. PCBONLINE provides comprehensive lead-free solutions. Our team is trained in all aspects of lead-free soldering, including solder tip selection, solder paste assessment, wave soldering assessment, process optimization, design principles, device assessment, reliability and equipment assessment, quality inspection and production cost. We have been actively implementing the transition to lead free products.

PCBONLINE always use the lead-free welding materials in production, such as solder paste for reflow soldering, tin bars for wave soldering, and tin wire for hand soldering. Lead-free soldering will be fully implemented. For some relatively expensive lead-free PCB parts, such as BGA, radiator parts, etc. PCBONLIN replaces the actual parts with non-functional "samples" to ensure correct reflow furnace temperature curves. Due to the metallic composition of lead-free solder, PCBONLINE trains inspectors to ensure that solder joints are of high quality and meet IPC-610D standards. Meanwhile, PCBONLINE also uses AOI, X_ray and other automatic equipment to find the soldering defects.

Normally, the customer will check the material in the BOM is lead-free or with lead. If you need help in checking whether the boards and materials meet the lead-free requirements, you can write us an email for getting suggestions. If you want to order, you can order by yourself online or email us.

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