Basic requirements for components and printed boards for wave soldering processe
1. Requirements for SMC/SMD
Surface mount pcb The metal electrode of the assembled component should have a three-layer termination structure. The component package and solder joint can withstand more than two times 260 °C ± 5 °C, 10s ± 0.5s (lead-free requirements 270 ~ 272 ° C / 10s ± 0.5s) Temperature shock of wave soldering. After the smt patch is soldered, the component package is not damaged, cracked, discolored, deformed, and is not brittle. The chip component has no peeling (uncapping) at the end, and also ensures that the SMT is processed after wave soldering. The change in electrical performance parameters meets the requirements defined in the specification.
2. Requirements for plug-in components
The short-insertion single-welding process is adopted, and the component leads should be exposed to the PCB soldering surface by 0.8~3mm.
3. Requirements for printed circuit boards
The PCB shall have a heat resistance of 260 ° C for more than 50 s (lead-free 260 ° C for more than 30 min or 288 ° C for more than 15 min, 300 ° C for more than 2 min), good resistance to copper stripping, solder mask There is still enough adhesion at high temperatures, and the solder mask does not wrinkle after soldering.
No charring phenomenon. Circuit boards are generally printed on RF-4 epoxy fiberglass cloth. PCBA printed circuit board warpage is less than 0.8%~1.0%.
4.Requirements for pcb design
Must be designed according to the characteristics of the mounted components.
The layout and layout of components should follow the principle of smaller components in front and avoiding mutual occlusion.
The difference between PCB and PCBA
What is a PCB? How did PCBA evolve? What is the difference between PCB and PCBA? Let's take a closer look below.
PCB is the abbreviation of Printed Circuit Board. Because it is made by electronic printing, it is called "printing" circuit board. PCB is an impor...