At any stage of the lead-free PCBA processing refers to the manufacturing PCBA that don't use lead. Traditionally, lead is used in the PCB during the welding process. But the lead is toxic, so harmful to humans. Consider the consequences, the limit of harmful substances directive (RoHS) prohibit the use of lead in PCBA process. Use less toxic substances instead of lead, almost no difference in the process of PCBA. This article detailed introduces the lead-free PCBA step by step process.
Lead-free PCBA guide
Lead-free PCBA process is divided into two basic parts, namely the assembling process and active process. Lead-free PCBA process steps involved in the following.
Assembling of lead-free PCB manufacturing involves three basic steps. These steps for error-free and precise PCB assembly laid a solid foundation. Assembling the steps of lead-free PCB assembly.
The process of analysis is similar to the prototype. Manufacturers to finished product lead-free PCB as the prototype. This can be the normal operation of the PCB, PCB or dummy parts can also be invalid. Used for assembling the template by contour tracking. Will lead free components design and prototype comparison, in order to ensure its compatibility with components.
Solder paste inspection:
Because of lead-free solder joints with metal appearance, the and based on the lead solder is very different, so the review is very important. In accordance with IPC - 610 - d standard check PCB shape and solder paste, and to ensure that the lead-free solder joint is firm and firm. In this step also test the moisture content, as compared with the traditional welding, in lead-free soldering, circuit board exposed to high water content.
The list of materials (BOM) and component analysis:
In this process, the customer must verify bill of materials (BOM), to ensure that components made of lead-free materials. Lead free components easy to be affected with damp be affected with damp, so manufacturers should be baking in the oven. Once carried out the necessary steps to begin the actual lead-free assembly.
Take the initiative to assemble steps
In the process of active assembly, in fact the PCB assembly. Of the steps involved in the active lead-free assembly.
Template is placed and the solder paste application:
In this step, place the forming stage of lead-free template on the plate. And then coated with lead-free solder paste. Usually, lead-free solder paste material for SAC305.
After coated with solder paste, the component is installed on the board. Component placement can be done manually, can also use the automatic machinery to complete. This is a pick and place operation, but should confirm the BOM validation phase used by components and carries on the tag. Machine or operator selection labeled components and place it into position.
At this stage to perform lead-free hole or manual welding. Either technology, THT and SMT, welding must be lead free.
Reflow furnace circuit board placed:
RoHS compliant PCB need high temperature heating to molten solder paste evenly. Therefore, place the PCBs in the reflow oven, solder paste melting there. In addition, the plate cooling in curing at room temperature molten solder paste. This helps to fix the component in its place.
Testing and packaging:
PCB has been tested in accordance with IPC - 600 - d standards. In this step test solder joints. After visual inspection is AOI and X ray examination. Physical and functional test before packing.
For lead-free PCB packaging, the use of anti-static discharge bag is very important. This to ensure that the final product will not suffer from static charges in transit is very important.
However, although the lead-free PCBA processing have a thorough understanding, but should still by experts to improve it. Constant day ca