Why do we need ROHS? A electronic product life cycle from research and development, application, scrap, buried in the soil, the harmful substances into the groundwater, through the food chain enrichment, finally we eat into the concentrated essence, to the next generation.
In the future, the implementation of ROHS standards according to the statistics, measurement of a TV set of various components and the PCB cost up to 300000 yuan, (who also can not afford to buy). Therefore, we must from the supplier production process and each process using materials to control and authentication.
From the ROHS to the product influence, mainly divided into the following several aspects. A, the effect of material composition of two, effect on reliability. By an electronics product comprises, influence on component suppliers. Effects on PCB suppliers. Effect on the component mounting business. Commonly used lead-free welding using the Sn-Ag-Cu temperature of 210 degrees.
Effect of 2 on component mounting business: lead-free solder tin lead solders to replace the original system, basic to meet the plait point to low, on the copper surface wettability. The current popular Sn-Ag-Cu system.
From the reliability point of view, mainly to meet the difference expansion properties, solder pin of the component, PCB brazing plate hot, otherwise it will lead to transverse shedding components. From the reliability point of view, mainly to meet the difference expansion properties, solder pin of the component, PCB brazing plate hot, otherwise it will lead to transverse shedding components. Effect of 3 on PCB manufacturers: Pcb as a carrier of various components, the reliability is very important. From the PCB point of view, the main sheet, soldering flux, character, surface treatment.
The soldering flux, character, surface treatment is the main control components, surface treatment using spray tin lead and gold or osp. For the plate, from the composition point of view there are many people misunderstood, because the plate containing bromine, as a component of flame retardant, but prohibited by the presence of bromine state is not ROHS of polybrominated biphenyls and polybrominated diphenyl ethers. For the plate, from the composition point of view there are many people misunderstood, because the plate containing bromine, as a component of flame retardant, but prohibited by the presence of bromine state is not ROHS of polybrominated biphenyls and polybrominated diphenyl ethers. From the reliability, several basic material and a PCB for copper, resin and glass fiber cloth. High temperature lead-free soldering, if the PCB as a three-dimensional rectangular, in the direction of XY, differences between the pad and resin thermal expansion will lead to off the pad, to lead the device and PCB detachment. In the Z direction, different heating hole copper and the resin expansion will lead to the hole wall is pulled to open. Inside the PCB, hierarchical difference between resin and glass cloth thermal expansion will lead to the entire pcb.
The design of laminated if not symmetrical, more easily lead to warpage generated resulting weld.
For the designers, the choice of plate is very important. At present the general hardware engineer material, TD>300 tg>170 CTE in the XYZ direction as small as possible. To meet the T260, T280, Q1000 best.