The PCB circuit board takes the insulating board as the base material and is cut into a certain size. At least one conductive pattern is attached on it, and holes (such as component holes, fastening holes, metallization holes, etc.) are arranged to replace the chassis of electronic components of previous equipment and complete the interconnection between electronic components
Selection of substrate raw materials for PCB:
Number of layers: 2 layers plate thickness: 1.6mm line width / line spacing: 0.8mm/0.3mm material: FR-4 copper thickness: 1oz aperture: 0.6mm process: oxidation resistance welding / character: dark green oil white character
1. Tin spray plate
Due to low cost, good solderability, good reliability and strongest compatibility, this kind of solder spray plate with good welding characteristics can not be used in the lead-free process because it contains lead. In addition, “tin silver copper spray tin plate” is difficult to obtain characteristic materials because most of them do not use this process.
2. Gold plated plate
The process cost of gold-plated plate is the highest among all plates, but at present, all existing plates are the most stable and most suitable for lead-free process, especially in some electronic products with high unit price and high reliability.
3. Gold plate
The biggest problem of this kind of substrate is the problem of “black pad”. Therefore, many large manufacturers do not agree to use the lead-free process, but most domestic manufacturers use this process.
4. Silver plate
Although “silver” itself has strong mobility, which leads to the occurrence of leakage, today’s “immersion silver plating” is not pure metal silver in the past, but “organic silver” co plated with organic matter, which can meet the needs of future lead-free process, and its solderability life is longer than that of OSP board.
5. OSP board
The OSP process has the lowest cost and simple operation. However, due to the assembly plant’s modification of equipment and process conditions and poor reprocessing performance, the popularity of this process is still not safe. Using this kind of plate, after high-temperature heating, the protective film pre coated on the pad is bound to be damaged, resulting in the decline of soldering tin, especially when the substrate is more and more serious after secondary reflow, Therefore, if another dip process is required in the process, the dip end will face the challenge of welding.
6. Tin plate
This kind of substrate is easy to be polluted and scratched. In addition, the oxidation and discoloration of the process (flux) will occur. Most domestic manufacturers do not use this process, and the cost is relatively high.