PCB News - Do you know the difference between gold-plated and gold-plated PCB board?

Do you know the difference between gold-plated and gold-plated PCB board?

Immersion gold boards and gold-plated boards are processes often used in PCB circuit boards. Many engineers are unable to accurately distinguish the differences between the two, and even some engineers believe that there is no difference between the two. This concept of long and short defects must be corrected in real time.

So how much influence will these two "golden board" facts have on the circuit board? I will give you a detailed lecture, and I will completely help the master to help the master to clarify the point of view.

1. What is gilding?

What we call gold plating on the entire board generally refers to "electroplating gold", "electroplating nickel gold plate", "electrolytic gold", "electric gold" and "electric nickel gold plate". There is a distinction between soft gold and hard gold (ordinary hard gold is Used for gold fingers), the reason is to dissolve nickel and gold (commonly known as gold salt) in chemical water, immerse the circuit board in the electroplating tank and turn on the current to generate a nickel-gold plating layer on the copper foil surface of the circuit board. Electro-nickel gold is widely used in electronic products because of its high hardness, abrasion resistance and resistance to oxidation.

2. What is Immersion Gold?

Immersion gold is a natural layer of plating through the method of chemical oxidation restoration. The general thickness is thicker, which is a kind of chemical nickel-gold layer accumulation method, which can reach a thicker gold layer.

The difference between gold-plated and gold-plated circuit boards

1. The thickness of ordinary immersion gold is much thicker than gold plating. Immersion gold will be golden yellow and yellower than gilding. It is more correct for customers to see the general situation. The crystal layouts formed by the two are different.

2. Because the layout of the crystals formed by immersion gold and gold plating is different, immersion gold is easier to weld than gold plating, and will not cause welding defects, which will cause customers to praise. At the same time, because sinking gold is softer than gold-plated, gold-plated gold finger plates are generally selected, and hard gold is wear-resistant.

3. As long as there is nickel gold on the immersion gold board, the signal transmission in the skin effect will not affect the signal in the copper layer.

4. Immersion gold has denser crystal layout than gold plating, and it is not easy to produce oxidation.

5. As the wiring becomes denser and denser, the line width and spacing have reached 3-4MIL. Gold plating is prone to short circuit of gold wire. As long as there is nickel gold on the immersion gold board, the gold wire will not be short-circuited.

6. As long as there is nickel and gold on the immersion gold board, the connection between the solder mask and the copper layer on the circuit is more stable. The project will not affect the spacing when making compensation.

7. It is generally used for relatively high-demand boards, and the flatness is better. Generally, heavy gold is used, and the heavy gold generally does not show signs of black pads after assembly. The flatness and stand-by life of the immersion gold board are as good as the gold-plated board.

The above is the difference between the gold plate and the gold plate. At the moment, the price of gold on the market is high. In order to reduce the cost, the manufacturers are not willing to produce the gold plate, and only make the gold plate with nickel and gold on the pad. The price is definitely much cheaper. I hope this introduction can provide reference and help to the master.

1. Immersion gold board and chemical gold board are a unified process product, and electric gold board and flash gold board are also a unified process product. It is really just the different names of different people in the PCB industry. Immersion gold board and electric gold board are more common in The title of the mainland peers, while the chemical gold board and flash gold board are more common in Taiwan's peers.

2. Immersion gold board/chemical gold board is officially called chemical nickel gold board or chemical nickel immersion gold board. The development of nickel/gold layer is plated by chemical accumulation; gold electric gold board/flash The gold plate is generally called electroplated nickel gold plate or flash gold plate. The development of the nickel/gold layer is plated by the method of direct current electroplating.

3. Please refer to the table below for the difference between the electroless nickel gold plate (immersion gold) and the electroplated nickel gold plate (gold plating):

The distinction between the characteristics of immersion gold plate and gold-plated plate:

Why doesn't "spray tin" in general?

As the integration degree of IC becomes higher and higher, IC pins become more denser.

The vertical tin spraying process is difficult to flatten the thin pads, which brings difficulty to the placement of smt; the shelf life of other tin spraying boards is very short.

The gold-plated plate just deals with these problems:

1. For the general placement process, especially for 0603 and 0402 ultra-small surface mounts, since the flatness of the pad is indirectly related to the quality of the solder paste printing process, it has a decisive impact on the quality of the previous reflow soldering, so, The whole plate gold plating is often seen in the high-density and ultra-small surface mount process.

2.In the trial production stage, the influence of factors such as component procurement is often not that the board is soldered immediately, but often it takes a few weeks or even a month to use it. The shelf life of the gold-plated board is better than that of lead. The tin alloy is many times longer so that the masters are willing to agree to adopt 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 has become denser, the line width and spacing have reached 3-4MIL.

So I brought the title of short circuit of gold wire:

As the frequency of the signal becomes higher and higher, the environment in which the signal is transmitted in the multi-plated layer due to the skin effect has a greater impact on the quality of the signal:

The skin effect refers to the high-frequency exchange of electricity, and the current gathers the trend in the general activity of the wire.

According to calculations, skin depth is related to frequency:

The other weaknesses of the gold-plated board have been listed in the distinction table between the immersion gold board and the gold-plated board.

Why choose immersion gold board instead of gold-plated board?

In order to deal with the above problems of gold-plated boards, PCBs with gold-plated boards mainly have the following characteristics:

1. Because the layout of crystals formed by immersion gold and gilded is different, the immersion gold will be golden yellower than gold-plated, and customers are more right.

2. Because the layout of crystals formed by immersion gold and gold plating is different, immersion gold is easier to weld than gold plating, and it will not cause welding defects, which will cause customers to praise.

3. As long as there is nickel gold on the immersion gold board, the signal transmission in the skin effect is on the copper layer and will not affect the signal.

4. Because the immersion gold has a denser crystal layout than gold plating, it is not easy to produce oxidation.

5. As long as there is nickel and gold on the immersion gold board, the gold wire will not be produced to form a short length.

6. As long as there is nickel and gold on the immersion gold board, the connection between the solder mask and the copper layer on the circuit is more stable.

7. The project will not affect the distance when making compensation.

8. Due to the different crystal layouts of gold-plated and gold-plated, the stress of the gold-plated plate is easier to control, and for products with bonding, it is more conducive to bonding processing. 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.

9. The flatness and stand-by life of the immersion gold board are as good as the gold-plated board.