Printed circuit board plating process

Printed circuit board plating process

Printed circuit board plating process, with the rapid development of electronic equipment and the rapid development of small, electronic equipment, the main structural parts printed circuit board, in order to meet the high density, high precision, miniaturization needs, printed circuit Plate manufacturing technology and technology has been greatly changed, which involved in the surface treatment technology changes are also great. It is well known that the purpose of electroplating is to provide printed circuit boards in the manufacture of their own poor and not inherent surface properties. The surface treatment from structural parts to printed circuit boards, albeit not only the same, but its electroplating itself is fundamentally the same. Of course, printed circuit board plating is relatively simple, less plating. The main purpose of electroless plating and electroplating of printed circuit boards is to ensure the solderability, protection, electrical conductivity and abrasion resistance of printed circuit boards.

Printed circuit board to achieve electric equipment approach, is the use of soldering and welding. Whether it is a connector or a surface mount, although the Denso process is not the same, but the technical requirements of the plating layer is the same. For printed circuit board surface coating is the most important of its solderability, it is to ensure that the connector or surface mount and circuit location should be a solid combination. And the reliability is ultimately determined by the welding situation. Modern production techniques typically use wave soldering or dip soldering on printed circuit boards while welding thousands of solder joints. However, since the electrical connection points are in contact with the molten solder for only one or two seconds, the surface of the component is fast It is important to completely wet the solder. The solder is spread on the surface to be welded to wet the surface of the device, and the welding process is completed by capillary action to allow the solder to pass through and fill the various parts of the contact. If the initial wetting effect is extremely poor, there will be defective solder joints or solder joints. Therefore, the choice of good solderability of the plating or coating is a very important technical work.

From the long experience of production practice proved that the new deposition of lead-tin alloy layer (tin content of 60%) the best solderability, which is measured by floating soldering results. However, due to the lead-tin alloy storage stage is too long, resulting in solderability degradation, that is, it is difficult to weld, especially in the hot and humid working environment conditions, the surface changes more, welding more difficult. Many manufacturers have developed a number of protective technology. Nevertheless, in order to more adapt to the miniaturization of electronic equipment, multi-functional needs, printed circuit board manufacturing technology constantly updated, the current widely used SMOBC process, still hot dip tin alloy (including 63%, 37%) coating The most important advantage is that it is capable of wetting the base metal and thus has a stronger, more stable metallurgical connection to the substrate to form a glossy coating surface. As a result of SMT printed circuit board, in order to ensure the quality of the surface mount device paste welding, from the technical point of view, the development and development of new coating - pre-coated heat flux, chemical nickel / gold surface coating Process has been widely used in surface-mount double-sided, multi-layer printed circuit board.

In addition to electroplating or hot dip tin-lead alloy coating and other advanced coating or plating technology, in order to have good electrical contact performance, printed circuit board plug parts need to surface treatment. This is because no matter how complicated the equipment or instrument is, there is always an electrical connection problem. The power input needs to be connected, and the devices and devices inside the circuit also require more connections from large electronic devices to miniaturized devices whose performance varies to varying degrees depending on the correct choice of the connected material and the coating It is very important to choose the contact surface coating, especially the requirements of small contact force and low voltage printed circuit board plug part of its important role is even more prominent. In the current printed circuit board manufacturing process to take hard gold plating method or nickel to the bottom of the gold or gold dip technology. Practical proof of the nickel-plated process for printed circuit board plug on the electrical and wear resistance of the technical requirements.

From the development trend of surface treatment technology, with the rapid development of microelectronics technology, printed circuit board manufacturing technology and technology, will develop a more advanced surface processing methods, but the overall trend is toward the development of less pollution, easy Operation and process stability.