Immersion Gold board and gold plating board are often used in PCB process. Many engineers are unable to distinguish them correctly, and even some engineers think that there is no difference between them. This is a very wrong point of view, which must be corrected in time.
So how will these two kinds of "gold plates" affect the circuit board? Now I'll explain it to you in detail and help you to make the concept clear.
1. What is gold plating?
Generally speaking, the whole board gold plating refers to "electroplate", "electroplate", "electroplate", "electrolytic gold", "electroplate" and "electroplate". There is a distinction between soft gold and hard gold (generally hard gold is used for gold fingers). The principle is to dissolve nickel and gold (commonly known as gold salt) in chemical medicine water, immerse circuit board in electroplating tank and connect current to generate nickel gold on the copper foil surface of circuit board Electrodeposited nickel and gold are widely used in electronic products because of their high hardness, wear resistance and non oxidizability.
2. What is Immersion gold?
Immersion gold is a kind of deposition method of electroless nickel gold layer, which can produce a thick gold layer by chemical oxidation-reduction reaction.
Difference between circuit board gold plate and gold plate
Difference between circuit board gold plate and gold plate The crystal structure of the two is different.
2. Due to the different crystal structure between Immersion gold and gold plating, Immersion gold is easier to weld than gold plating, which will not cause bad welding and cause customer complaints. At the same time, just because the gold is softer than the gold, so the gold finger board is generally gold-plated, hard gold wear-resistant.
3. There is only nickel and gold on the solder pad, and the signal transmission in the skin effect is that the copper layer will not affect the signal.
4. The crystal structure of Immersion gold is more compact than that of gold plating, which is not easy to produce oxidation.
5. With the increasing density of wiring, the line width and spacing have reached 3-4mil. Gold plating is easy to produce short circuit. Only the pad of the gold sinking plate has nickel gold, so it will not produce short circuit of gold wire.
6. Only the pad of the gold sinking plate has nickel gold, so the combination of resistance welding and copper layer on the line is more firm. The project will not affect the spacing when making compensation.
7. It is generally used for boards with relatively high requirements, with good flatness. Generally, Immersion gold is used, and the phenomenon of black pad after assembly will not appear. The flatness and service life of gold plate are as good as that of gold plate.
The above is the difference between the Immersion gold and the gold plate. Nowadays, the price of gold is very high. In order to save costs, many manufacturers are not willing to produce the gold plate, but only to make the gold plate with nickel on the pad, which is indeed much cheaper. I hope this introduction can provide you with reference and help.
1. The gold sinking plate and the gold melting plate are the same process products. The gold plating and the gold flashing plate are also the same process products. In fact, they are just different names of different people in the PCB industry. The gold sinking plate and the gold melting plate are more common in the mainland, while the gold melting plate and the gold flashing plate are more common in Taiwan.
2. Generally speaking, the gold plating plate / gold plating plate is formally called as electroless nickel gold plate or nickel plating plate, and the growth of nickel / gold layer is plated by chemical deposition; generally speaking, the gold plating plate / gold flash plate is formally called as nickel gold plate or gold flash plate, and the growth of nickel / gold layer is plated by direct current plating.
3. See the following table for the mechanism difference between chemical nickel gold plate (gold deposition) and electroplated nickel gold plate (gold plating):
A kind of
Difference between the characteristics of gold plate and gold plate:
A kind of
Why not spray tin?
With the increasing integration of IC, the IC pin is more and more dense. However, it is very difficult for the vertical tin spray process to flatten the thin solder pad, which brings difficulties to SMT mounting; in addition, the shelf life of the tin spray plate is very short. The gold plating plate solves these problems:
1. For surface mounting process, especially for 0603 and 0402 ultra-small surface mounting, because the flatness of solder pad is directly related to the quality of solder paste printing process and plays a decisive role in the quality of reflow welding, so the whole board gold plating is common in high-density and ultra-small surface mounting process.
2. In the trial production stage, the influence of component purchase and other factors is often not that the plate is welded immediately when it comes, but it often needs to wait for weeks or even months to use. The shelf life of gold-plated plate is many times longer than that of lead tin alloy, so everyone is willing to use it. Besides, the cost of gold-plated PCB in the sample stage is almost the same as that of lead tin alloy plate. But as the wiring becomes more and more dense, the line width and spacing have reached 3-4mil. Therefore, the problem of short circuit of gold wire is brought:
With the increasing frequency of the signal, the effect of the signal transmission in the multi coating caused by skin effect on the signal quality is more obvious
Skin effect refers to: high frequency alternating current, the current will tend to focus on the surface of the wire flow. According to the calculation, skin depth is related to frequency:
Other disadvantages of the gold plate are listed in the difference table between the gold plate and the gold plate.
Why choose gold plate instead of gold plate?
In order to solve the above problems of gold plate, the PCB with gold plate mainly has the following characteristics:
1. Because the crystal structure of gold deposition and gold plating is different, the gold deposition will be golden yellow, which is more yellow than gold plating, and the customer is more satisfied.
2. Due to the different crystal structure between gold deposition and gold plating, gold deposition is easier to weld than gold plating, which will not cause bad welding and cause customer complaints.
3. Because there is only nickel and gold on the solder pad of the gold sinking plate, the signal transmission in the skin effect is that the copper layer will not have any effect on the signal.