While some parts of the PCB may bend upwards, other parts may bend downwards, representing positive and negative curvature. Due to various stresses, this does not happen, and some parts of the PCB do not touch the surface. Ideally, when kept on a flat reference surface, all parts of the PCB should be in contact with the surface. We recommend changes in PCB design and controls in the assembly process to reduce the impact of PCB warpage, thereby providing improvements in margin for the board assembly process. We share the results of detailed studies on PCB design, reflow pallet design, and methods of controlling and containing PCB warpage. Rush PCB presents solutions addressing the PCB warpage issue. It also affects the formation of solder joints during the reflow soldering process-leading to SMT assembly defects. Warpage impacts the assembly yield, as it affects all aspects of the process.įor instance, PCBs with excessive warpage affect the quality of paste printing during the solder paste printing process. According to Rush PCB, the use of thin multi-layer PCBs of less than 40 mils (1 mm) and very small SMT components is also leading to issues of warpage in the assembly process. The trend comes from increasing customer demands for smaller form factor for electronic devices. The electronics industry is presently using thinner printed circuit boards (PCBs) and smaller SMT electronic components than they did earlier.
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