What Are The Differences Between The Two Processes Of Tin Spraying And Immersion Tin For Circuit Boards?
Nov 14, 2022
There are two common processes for PCB circuit boards: spray tin and immersion tin, both of which are a surface treatment method to meet the requirements of lead-free soldering. However, in the circuit board process, immersion tin is not known to most people. Let's talk about the difference between spray tin and immersion tin in detail with the technicians of multi-layer circuit boards.
The difference between spray tin and immersion tin
1. Process flow
Tin spraying: pretreatment - tin spraying - testing - forming - appearance inspection.
Immersion Tin: Test - Chemical Treatment - Immersion Tin - Forming - Visual Inspection.
2. Process principle
Tin spraying: The main purpose is to directly invade the PCB board into the molten tin paste. After being leveled by hot air, a dense tin layer will be formed on the copper surface of the PCB.
Immersion tin: It mainly uses the displacement reaction to form a very thin tin layer on the PCB surface.
3. Physical properties
Spray tin: the thickness of the tin layer is about 1um-40um, the surface structure is relatively dense, the hardness is high, and it is not easy to scratch; the spray tin only has pure tin in the production process, so the surface is easy to clean and can be stored under normal temperature for a period of time. years, and the problem of surface discoloration is not easy to occur during the welding process.
Immersion tin: The thickness of tin is about 0.8um-1.2um, the surface structure is relatively loose, the hardness is small, and it is easy to cause surface scratches; Immersion tin undergoes complex chemical reactions, and there are many agents, so it is not easy to clean and the surface is easy The residual potion is prone to discoloration problems during welding, and the storage time is short. It can be stored for three months at normal temperature. If the time is long, discoloration will occur.
4. Appearance characteristics
Spray tin: the surface is brighter and more beautiful.
Immersion tin: The surface is light white, dull and easy to change color.
