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<p><strong>• Based on manufacturing technology</strong></p><p><br></p><p><br></p><p>According to manufacturing technology, <a href="https://www.atech<a href="https://www.atechpcb.com/pcb-manufacturing" target="_blank">pcb</a>.com/pcb-manufacturing" rel="noopener noreferrer" target="_blank"><strong>PCB</strong></a> surface treatment can be divided into surface coating and metal coating.</p><p><br></p><p><br></p><p>Surface coating</p><p><br></p><p><br></p><p>Surface coating refers to the process of physically adding a heat-resistant and solderable thin coating on the copper surface. The main feature of the surface coating is that it can provide a pure copper surface for the solder during the soldering process. Surface finishes like HASL (Hot Solderability Level) or OSP (Organic Solderability Preservative) fall into this category.</p><p><br></p><p><br></p><p> Metal coating</p><p><br></p><p><br></p><p>Metal plating refers to the process of generating heat-resistant solderable metal plating on the pure copper surface of the<a href="https://www.atechpcb.com/pcb-manufacturing" rel="noopener noreferrer" target="_blank"> PCB </a>pad by chemical plating and electroplating, such as ENIG (electroless nickel and gold plating), ENEPIG (electroless nickel and chemical palladium) immersion gold) , Shen Jin etc.</p><p><br></p><p><br></p><p><strong>• According to the application effect</strong></p><p><br></p><p><br></p><p>According to the application effect, the surface finish can be divided into three categories: flux for welding on the coating of the isolation layer, flux for welding on the metal coating of the diffusion layer and flux for welding on the isolation layer of the metal coating.</p><p><br></p><p><br></p><p>Category 1: Flux is soldered on the coating of the isolation layer.</p><p><br></p><p><br></p><p>The main characteristic of this type of surface coating is that during high-temperature soldering, the molten solder will drift on the solder surface after leaving the copper. However, IMC will be generated at the solder joint interface, which will increase the possibility of defects.</p><p><br></p><p><br></p><p>Category 2: Flux welding on the metal coating of the diffusion layer.</p><p><br></p><p><br></p><p>The emergence of this technology aims to eliminate IMC, but it has obvious disadvantages. On the one hand, it tends to cause proliferation; on the other hand, it tends to cause proliferation. On the other hand, it tends to make the board brittle, and then cause circuit defects.</p><p><br></p><p><br></p><p>Category 3: Flux welding on the isolation layer of the metal coating.</p><p><br></p><p>The main advantage of this technique is that the solder is soldered to the surface of the metal coating isolation layer, rather than directly soldered to the copper surface. Therefore, stable IMC will not be generated at the interface, nor will it cause diffusion between metals.</p>
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