PCB News - Shenzhen PCB Factory: Chemical nickel gold vs electroplated nickel gold, which is better?

Shenzhen PCB Factory: Chemical nickel gold vs electroplated nickel gold, which is better?

Shenzhen Circuit Board Factory: Due to the outstanding solderability and flatness of the chemical nickel gold and nickel gold electroplating process, more and more PCB proofing of electronic products use the nickel gold surface treatment process.

In PCB proofing, which one is more suitable for surface treatment of chemical nickel gold or electroplated nickel gold?

The electroless nickel-gold process is relatively simple, and only two key chemical solutions are used, namely, the electroless plating solution containing hypophosphite and nickel salt and the acidic gold water (containing KAu(CN)2). The process generally goes through pickling, micro-etching, activation, electroless nickel plating, cleaning, gold immersion and other processes. The key step is to autocatalyze the electroless nickel plating on the copper pad, and control the thickness of the nickel plating by controlling the time, temperature, and pH value; then use the activity of the plated fresh nickel to immerse the nickel-plated pad In acidic gold water, gold is replaced from the solution to the surface of the pad through a chemical displacement reaction, and part of the nickel on the surface is dissolved in the gold water, so as long as the replaced gold completely covers the nickel layer, the replacement reaction automatically stops. Then the process can be completed after cleaning the dirt on the surface of the pad. At this time, the thickness of the gold-plated layer is usually only about 0.03 to 0.1 microns, and the thickness of the plating layer in various shapes or parts is uniform.

Nickel-gold electroplating is to deposit a low-stress nickel plating layer of about 3 to 5 microns on the copper substrate of the pad by applying electricity, and then plate a layer of about 0.01 to 0.05 microns on the nickel. Gold; In the case of a certain plating solution, the thickness of the plating layer can be controlled by controlling the plating time. Other process links such as cleaning and micro-etching are basically the same as chemical nickel-gold. The biggest difference between electroless nickel gold and electroplated nickel gold lies in the formulation of the plating solution and whether power is required. For bare copper boards coated with solder mask, it is usually not easy to add electricity to each area that needs to be plated, so chemical plating can only be used at this time.

Whether it is chemical nickel gold or electroplated nickel gold, the real need to pay attention to is the nickel plating, because it is nickel instead of gold that really needs to be welded to form intermetallics. Gold is only to protect the nickel from oxidation or corrosion. The gold layer is welding It dissolves into the solder from the beginning.

In PCB proofing, both chemical nickel gold and electroplated nickel gold belong to special processes, which have certain technical thresholds and operational difficulties, and have a high error rate. Therefore, general PCB board proofing manufacturers seldom do it.