The main factor that determines the quality and positioning of a board is the surface treatment process.  For example, OSP can spray tin, gilt and sink gold.  Relatively speaking, the metal is facing the high-end board.  Sunken gold due to good quality, relative to the cost is relatively high.  So many customers choose the most commonly used tin spraying process.  Spray tin is divided into lead spray tin (that is, hot air leveling) and lead-free spray tin.  The following is a look at the differences between each process;  

Do the circuit board for a long time, there will always be a variety of problems, such as some end users require to do lead-free spray sample, get the hand welding debugging, manual welding always feel no lead easy to tin.  At this time, it is not quite sure whether it is the cause of the circuit board factory or the welding itself.  

In fact, when you're welding patterns by hand, it's easier to solder with lead.  Lead is much more impregnable than lead-free.  Lead increases the activity of the tin wire during welding.  But lead is toxic, and lead-free tin has a high melting point, making it a much stronger joint.  

Lead and lead are also visually discernible: leaded tin is brighter, lead-free tin (SAC) is dimmer.  

Lead-free process: one of the basic concepts of lead-free electronic assembly is that the solder used in soft brazing is lead-free (PB-Feer SOder), whether manual soldering, dip soldering, wave soldering or reflow soldering.  Lead-free solder does not mean that the solder is 100% lead free.  Lead is present as a basic element in leaded solders.  In lead-free solder, the base element does not contain lead.  

Lead process: In the traditional soft brazing process of printed plate assembly, tin-lead (SN-Pb) solder is generally used, in which lead exists and plays a role as a basic element of solder alloy.  Lead solder alloy has low melting point, low welding temperature, less thermal damage to electronic products;  Lead solder alloy has small wetting Angle, good weldability, and the possibility of "fake welding" of solder joints is small;  The toughness of solder alloy is good, and the vibration resistance of solder joint is better than that of lead-free solder joint.  

Compared with. Osp lead-free tin spraying and gold precipitation process these three surface treatments.  Although they are all environmentally friendly,  

But most plain old boards do more of the first two.  Because the cost is lower.  

Osp is suitable for fine lines and SMT spacing.  Low operating temperature, no damage to the sheet material, easy to rework repair.  

However, the osP process produced by the board is not acid resistant, high humidity environment will affect its welding performance.  Need to be welded in as short a time as possible sink gold and gold plating although are more resistant to wear.  But there is a difference with the two words: gold plating process, the gold is only plated on the surface, the side or only copper and nickel, easy to oxidation over a long time, this is a defect of the gold plating process, can not be used in high requirements of the occasion.  

Do the whole pad, including the side can be plated with nickel gold, is currently the most stable, can be used in a variety of occasions, but the nickel gold has a headache, is more difficult to find the problem, is not as adhesion as gold, easy to fall off after a period of use.