What are copper base and nickel base PCB?
Some friends who concern about Shenzhen Grande should often hear Shenzhen Grande talks about the "copper" base and the "nickel" base circuit board and its advantages and disadvantages, but Shenzhen Grande believes that there are still many friends about are "copper" base and the "nickel" base circuit board are not very well understood.
In fact, the so-called "copper" base circuit board is that no matter what kind of surface treatment, when the solder is finally formed, only "copper" will react with the "tin" in the solder paste to form the copper tin IMC compound Cu6Sn5. In the "nickel" base, "nickel" reacts with "tin" in solder paste to form nickel-tin-IMC compound Ni3Sn4.
Let's take a look at these surface treated boards as "copper" bases or "nickel" bases.
What is OSP (Organic Solderability Preservative)?
OSP chemically grows a layer of organic copper on the surface of copper. This layer of organic copper protectant can be quickly removed by flux at high temperatures and exposed to clean copper surface to form solder joints with solder paste. Therefore, the actual formation of IMC is the "tin" of solder paste and the "copper" on the PCB. So OSP is a "copper" base board.
What is HASL (Hot Air Solder Leveling, tin plate)?
HASL sprays a layer of tin on the surface of the copper foil to protect the copper foil, and then forms a wind knife with hot air to level the tin surface. Because the solder paste itself is a tin-based mixture, the tin paste and the HASL tin will fuse together when soldering, and the final will form an IMC with tin or a "copper" foil on the PCB. Therefore, HASL is also a "copper" base circuit board.
What is ImSn (Immersion Tin)?
ImSn only chemically coats the surface of the copper foil with a layer of "tin". Since it is all tin coating, the result is the same as HASL. The final IMC is actually the "tin" of the solder paste and the PCB. "Copper". So ImSn is also a "copper" base board.
What is ENIG (Electroless Nickel Immersion Gold, electroless nickel immersion gold)?
ENIG uses a chemical method to apply a layer of "nickel" on the surface of the copper foil, and then apply a layer of "gold". The effect of "gold" on the ENIG circuit board is only to protect the nickel layer from the air. Contact and oxidation affect the quality of the solder afterwards. During the soldering process, gold dissolves rapidly into the solder paste, and finally the IMC is formed with "tin". Therefore, ENIG is a "nickel" base circuit board.
