Analysis of the advantages and disadvantages of OSP and application issues

OSP (Organic Solder Protective Sheet) as a surface treatment technology has shown significant advantages in electronics manufacturing, especially in fine pitch devices and applications with high coplanarity requirements, but also comes with some challenges and considerations. The following is a detailed analysis of OSP applications, advantages, shortcomings and application issues:

Advantages

Relatively Lowest Cost: OSP is more economical than other surface treatment technologies (e.g., gold plating, silver plating, etc.) and is suitable for mass production applications.

Flat Pad Surface: The surface of the pads after OSP treatment is extremely flat, which helps to improve soldering quality and reduce soldering defects.

Compatible with lead-free process: With the advancement of environmental protection regulations, lead-free soldering has become the mainstream, OSP perfectly adapted to this demand, to ensure the reliability of soldering and environmental protection.

Many supplier resources: There are many suppliers providing OSP services in the market, with a wide range of choices, which is conducive to the flexible adjustment of the supply chain for enterprises.

Shortcomings Special process requirements: In the PCB manufacturing process, OSP requires special process control to ensure its effectiveness and quality.

Short storage period: OSP treated boards have a limited storage period, generally no more than 3 months, otherwise the solderability will be significantly reduced, and even need to be scrapped.

Poor thermal stability: After the first reflow soldering of OSP, subsequent soldering operations must be completed within a specified period of time to avoid solderability degradation.

Wave soldering is particularly sensitive and more susceptible due to its short soldering time.

Application Limitations: OSP is not well suited for veneer boards with EMI grounding areas, mounting holes, test pads, and veneer boards with crimp holes, which limits its use in some specific applications.

Application Issues Solderability degradation with heat: Although OSP is not volatile at reflow soldering temperatures, too much thinning of the OSP can affect its ability to resist oxidation. Oxidation of the copper surface is the primary cause of solderability degradation and is affected by the number of reflow cycles.

Application experience: Strictly control the storage time of OSP sheet, more than 1 year solderability becomes unreliable, need to be scrapped or reworked. OSP after a high temperature, weldability significantly reduced, so need to control the number of times to weld, and to assess the number of times the OSP flux resistance. The time between the first pass through the furnace and the final completion of the soldering should be controlled within 48 hours to control the effect of moisture absorption on solderability. Avoid the use of PA and other cleaning agents to prevent the impact of solderability; if poor solder paste printing is encountered, it should be remedied by reprinting methods. For OSP boards with excessive moisture absorption, short drying process can be used to restore their solderability.

In summary, OSP as a cost-effective surface treatment technology, has a wide range of application prospects in the field of electronic manufacturing. However, when adopting OSP technology, enterprises need to fully understand its advantages, disadvantages and application problems, and take corresponding measures to ensure welding quality and productivity. At the same time, with the continuous progress of technology and increasingly strict environmental regulations, OSP technology will continue to develop and improve to better meet market demand.