Production requirements of OSP PCB circuit boards
1. The incoming material of PCB shall be vacuum packed with drying agent and humidity indicator card.When transporting and storing PCB with OSP, separate paper should be used between PCB boards with OSP to prevent friction damage to OSP surface.
2, not exposed to direct sunlight environment, maintain good warehouse storage environment, relative humidity: 30 ~ 70%, and temperature: 15 ~ 30 ℃, the retention time is less than 6 months.
3. When unsealing at the SMT site, vacuum packaging, drying agent, humidity display board must be checked. Unqualified boards shall be returned to the manufacturer for rework treatment, and be put on line within 8 hours.Do not disassemble multiple packages at one time, in accordance with the principle of “disassemble as much as possible and produce as much as possible”. Otherwise, if the exposure time is too long, it will easily lead to mass welding defects.
4. Do not stay in the furnace as soon as possible after printing (no longer than 1 hour), as the flux in the solder paste is highly corrosive to OSP films.
5, maintain good workshop environment: 40 ~ 60% relative humidity, temperature: 18 ~ 27 ℃.
6. Avoid direct contact with the PCB surface by hand during the production process, so as to avoid the oxidation of PCB surface contaminated by sweat.
7. After the SMT single-sided patch is completed, the second SMT part patch assembly must be completed within 12 hours.
8. Finish the SMT in as short a time as possible (up to 24 hours).
9. OSP PCB circuit board should not be baked in damp. High temperature roasting can easily cause OSP discoloration and deterioration.
10. The unused overrunning empty plates, the wet empty plates, and the empty plates cleaned by poor batch printing shall be returned to the PCB manufacturer for OSP heavy processing before use. However, the same plate cannot be used for more than three times, otherwise it needs to be scrapped.
II. Design requirements of SMT solder paste steel net for OSP PCB circuit board
1. OSP is good for solder paste forming due to its formation and the PAD does not provide a part of solder, so the opening should be appropriately enlarged to ensure that the solder can cover the entire solder PAD.When PCB circuit board changed from spout to OSP, the steel grid required re-opening.
2. After the opening is increased appropriately, in order to solve the problem of exposing copper of SMT CHIP tin beads, stelae and OSP PCB circuit board, we can change the design method of opening holes of solder paste printing steel net to concave design, especially pay attention to preventing tin beads.
3. If the part position on the PCB is not placed for some reason, the solder paste shall cover the solder pad as much as possible.
4. In order to prevent the oxidation of bare copper foil and the problem of reliability, it is necessary to consider putting solder paste on the front side of ICT test points, screw holes and bare through holes (solder on the back wave crest), and fully consider opening holes when making steel mesh.
III. OSP PCB PCB printed solder paste bad board processing requirements
1. Try to avoid printing errors, as cleaning will damage the OSP protective layer.
2. When PCB printed solder paste is not good enough, as OSP protective film is easily eroded by organic solvent, all OSP PCB boards cannot be soaked or cleaned with high volatile solvent. The solder paste can be wiped with 75% alcohol on non-woven cloth and dried with air gun.Do not clean with IPA, be sure not to use a stirring knife to scrape off the solder on the poor printing plate.
3. The soldering operation of SMT patch solder on the PCB surface of the PCB should be completed within 1 hour after the completion of the improper cleaning of PCB.
4. If the batch quantity (such as 20PCS or more) is not well printed, centralized return to the manufacturer can be adopted to deal with it.
IV. OSP PCB circuit board temperature curve setting requirements
OSP PCB circuit boards of reflow soldering temperature curve setting requirements and spray tin plate basic same, maximum peak temperature can be appropriately reduced 2-5 ℃.
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