PCB Technical - What is the difference between gold-immersed and gold-plated boards in the production of PCB preset circuit boards?

Immersion gold boards and gold-plated boards are currently used in the production of PCB preset circuit boards.

With the increasing integration of IC, the more IC pins become denser. However, it is difficult for the vertical spray tin process to flatten the thin pads, which brings difficulty to the placement of SMT; the standby life of the additional tin spray board is very short. And gold plating just happens to solve these problems. Since the flatness of the pad is directly related to the quality of the solder paste printing process, it has a voting effect on the quality of the subsequent reflow soldering. Therefore, the entire plate gold plating is seen from time to time in the high density and ultra-small scale surface mount process. arrive. In the trial manufacturing stage, it is often not affected by factors such as component acquisition and purchase that the wrench will be welded immediately, but often have to wait for a few weeks or even a month before using it. The tin plate is many times longer. So everyone is happy to think it is appropriate and use it. Besides, the cost of gold-plated PCB is similar to that of lead-tin alloy board in the sample stage.

Gold plating generally refers to electroplated gold, electroplated nickel gold plate, electrolytic gold, electrolytic gold, electrolytic nickel gold plate, there is a difference between soft gold and hard gold (usually used as a gold finger). The principle is to dissolve nickel and gold (commonly known as gold salt) in a chemical solution, immerse the circuit board in an electroplating cylinder and pass an electric current to form a nickel-gold plating layer on the copper foil surface of the circuit board. The unique characteristics of high hardness, wear resistance, and resistance to oxygenation of the coating have been widely used in the name of electronic products. Immersion gold is a method of chemical oxygenation to restore the response to generate a layer of plating. The general thickness is thicker, which is a kind of chemical nickel-gold layer deposition method, which can reach a thicker gold layer, which is generally called immersion gold.

In PCB presets, the difference between gold-immersed board and gold-plated board
1. Immersion gold is different from the crystal structure formed by gold plating. Immersion gold is thicker for gold than gold plating. Immersion gold will be golden yellow and yellower than gold plating, and customers are more satisfied.

2. Immersion gold is different from the crystal structure formed by gold plating. Immersion gold is easier to weld than gold plating, and will not lead to poor welding and cause customer complaints. The stress of immersion gold plate is easier to control, and for products with bonding, it is more helpful to the processing of bonding. At the same time, because the immersion gold is softer than the gilding, the immersion gold plate is not wear-resistant as the gold finger.

3. The immersion gold board only has nickel and gold on the pads. In the skin effect, the signal transmission is on the copper layer and will not affect the signal.

4. Immersion gold is more delicate and precise in crystal structure than gold plating, and it is not easy to produce oxygenation.

5. As the wiring becomes denser, the line width and spacing have reached 3-4MIL. Gold-plated is prone to initiation of gold wire short circuit. The immersion gold board only has nickel gold on the pad, so it will not produce gold wire short circuit.

6. The immersion gold board only has nickel and gold on the pads, so the solder mask on the circuit and the copper layer are more solid. The project will not affect the spacing during the repayment.

7. It is generally used for wrenches with relatively high requirements. The flatness is better. Generally, it is considered appropriate to use heavy gold, which will not show the black pad phenomenon after assembly. The flatness of the immersion gold plate and the life expectancy of use are as good as the gold plate