At present, SYS Tech requires that the thickness of OSP can meet the requirements of twice reflow soldering and once wave soldering. PCB Manufacturers normally do 0.2~0.35μm thickness OSP. During soldering, the protective film decomposes, volatilizes, and melts into the solder paste or acid flux, exposing the copper surface, making the solder and clean copper reacts. Because of its low production cost and mature technology, it has been widely used.
Advantages, disadvantages and applications of OSP process
flat and cheap, OSP only loves copper surfaces, it has no affinity for other surfaces such as solder mask, and will not adhere to its surface, so it is widely used.
① The storage time is short, and the storage period is 3 months under vacuum packaging conditions. When storing, keep away from acidic substances and the temperature should not be too high, otherwise it will volatilize.
② Difficult to detect, colorless and transparent.
③ OSP itself is insulated, and Imidazole OSP forms a thicker coating, which will affect electrical testing and cannot be used as a coating for electrical contact surfaces such as golden fingers, keyboard keys, test points, etc.
④Reflow soldering cannot be performed multiple times, generally 3 times. It needs to be considered in double-sided reflow soldering and rework. After several generations of improvements, its heat resistance, storage life, and flux compatibility have been greatly improved.
⑤The soldering temperature is relatively increased to 225℃, and a stronger (acidic component) flux must be added to eliminate the protective film during the soldering process, otherwise it will cause soldering defects.