First, Shen Jin uses a method of chemical deposition. A chemical layer is formed by a chemical oxidation-reduction reaction method. Generally, the thickness is relatively thick. It is a kind of chemical nickel-gold-gold layer deposition method and can achieve a thick gold layer.
Second, gold plating uses the principle of electrolysis, also called electroplating. Most other metal surface treatments use electroplating.
In the actual product application, 90% of the gold plate is the immersed gold plate, because the poor solderability of the gold plate is his fatal flaw, and it is also the direct cause of many companies to give up the gold plating process!
Immersion gold process deposited on the surface of the printed circuit with stable color, good brightness, smooth plating, and good solderability of nickel gold plating. Basically, it can be divided into four stages: pre-treatment (oil removal, micro-etching, activation, post-dip), nickel precipitation, heavy gold, post-treatment (waste water washing, DI water washing, drying). Immersion gold thickness is between 0.025-0.1um.
Gold is applied to the surface treatment of circuit boards because of its high electrical conductivity, good oxidation resistance, and long service life. The fundamental difference between gold-plated and gold-immersed boards is that gold-plating is hard gold (abrasion-resistant), and gold is a soft gold. (Not wearable).
1. The crystal structure formed by Immersion Gold and Gold Plating is different. Immersion Gold is much thicker than Gold Plating. Immersion Gold will be golden yellow and yellower than Gold Plating (this is the method of distinguishing between gold plating and gold Immersion). a) Gold plating will be slightly white (nickel color).
2. The crystal structure formed by Immersion Gold and gold plating is not the same. Immersion Gold is easier to weld than Gold Plating and will not cause bad welding. The stress of the Shenjin plate is easier to control, and it is more conducive to the bonding process for bonded products. At the same time, because gold is more gold-plated than gold, the gold-fingered gold finger is not wear-resistant (shortcomings of the gold plate).
3. There are only nickel-gold on the pad in the gold-immersed plate. The signal transmission in the skin effect does not affect the signal in the copper layer.
4, Shen gold is more dense than the gold plating crystal structure, not easy to produce oxidation.
5, with the increasing demand for circuit board processing accuracy, line width, spacing has reached 0.1mm below. Gold plating is prone to gold short circuit. The gold plate only has nickel and gold on the pad, so it is not easy to produce a gold short circuit.
6. The gold plate only has nickel gold on the pad, so the combination of the solder resist on the line and the copper layer is stronger. The project will not affect the spacing when making compensation.
7, for the higher requirements of the board, flatness requirements are better, the general use of gold, Shen Jin generally does not appear after the assembly of the black mat phenomenon. The flatness and service life of the gold plate are better than that of the gold plate.
So at present most factories use the gold sinking process to produce gold plates. However, the gold-immersed process is more expensive than the gold-plating process (more gold content), so there are still a large number of low-cost products using gold plating process.
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