In electronic products, gold is widely used in contact because of its good electrical conductivity, such as key boards, gold finger boards, etc. The fundamental difference between gold-plated boards and immersion gold boards is that gold plating is hard gold, and immersion gold is soft gold. Why do we need two different processes to make circuit boards? Let's analyze the electrical performance below.

　　 1. The difference between immersion gold plate and gold-plated plate: Immersion gold is produced by chemical deposition, and gold plating is produced by electroplating and ionization.

　　 2. What is a gold-plated circuit board? Why use a gold-plated circuit board?

　　Gold-plated circuit boards will be gold-plated on the entire board during production, not only the pads, but also the wiring and copper locations will be covered with gold. Gold plating generally refers to electroplating gold, also called electroplated nickel gold plate, electrolytic gold, electro-gold, electro-nickel gold plate, there is a distinction 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 chemical water, immerse the circuit board in the electroplating cylinder and pass an electric current to form a nickel-gold plating layer on the copper foil surface. The characteristics of wear resistance and oxidation resistance are widely used in electronic product names.

　　 With the increasing integration of IC, the more IC pins become denser. The vertical spray tin process is difficult to flatten the thin pads, which brings difficulty to the placement of SMT; in addition, the shelf life of the spray tin plate is very short. The gold-plated board just solves these problems:

1. For the surface mount process, especially for ultra-small surface mounts of 0201 and below, because the flatness of the pad is directly related to the quality of the solder paste printing process, it has a decisive influence on the quality of the subsequent reflow soldering, so the whole board Gold plating is common in high-density and ultra-small surface mount processes.

2. In the trial production stage, due to factors such as component procurement, it is often not that the PCB board production is completed and the SMT placement process can be carried out immediately. Sometimes it takes several weeks or even months to start to arrange the SMT placement and the gold-plated board. The shelf life is many times longer than that of pewter, so everyone is willing to use it. Besides, the cost of the gold-plated PCB in the sample stage is almost the same as that of the lead-tin alloy board. But as the wiring becomes denser, the line width and spacing have reached 3-4MIL. Therefore, the problem of gold wire short circuit is brought about. As the frequency of the signal becomes higher and higher, the signal transmission in the multi-plated layer caused by the skin effect has more obvious influence on the signal quality. (Skin effect refers to: high frequency alternating current, the current will tend to concentrate on the surface of the wire. According to calculations, the skin depth is related to frequency.)