The difference and advantages and disadvantages of gold plating and immersion gold process
(1) Why use gold-plated plates
As ICs become more integrated, the IC pins are more dense. The vertical tin-spraying process is difficult to flatten the fine pads, which makes the placement of the SMT difficult; in addition, the shelf life of the tin-plate is very short. The gold-plated plate solves these problems: 1 For the surface mount process, especially for the 0603 and 0402 ultra-small surface mounts, because the flatness of the pad is directly related to the quality of the solder paste printing process, from the quality of the reflow soldering To the decisive impact, the entire plate is plated in high density and ultra-small surface mount processes. 2 In the trial production stage, the factors such as component procurement are often not welded immediately, but often have to wait for a few weeks or even a month. The shelf life of the gold plate is better than that of lead tin. Hehe. In addition, the cost of the gold-plated PCB in the proofing stage is comparable to that of the lead-tin alloy sheet. But as the wiring becomes denser, the line width and spacing have reached 3-4 MIL. Therefore, the problem of short circuit of gold wire is brought about: as the frequency of the signal becomes higher and higher, the effect of the signal transmission in the multi-plating layer on the signal quality is more obvious due to the skin effect: the skin effect refers to: high frequency With alternating current, the current will tend to concentrate on the surface of the wire.
(2) Why use immersion gold
In order to solve the above problems of gold-plated plates, the PCBs using the immersion gold plate mainly have the following characteristics:
- Because the crystal structure formed by immersion gold and gold plating is different, Shenjin will be golden yellow and more yellow than gold plating, and customers are more satisfied.
- Because the crystal structure formed by immersion gold and gold plating is different, immersion gold is easier to weld than gold plating, which will not cause poor soldering and cause customer complaints.
- Because the gold plate only has nickel gold on the pad, the signal transmission in the skin effect is not affected by the signal in the copper layer.
- Because of the gold plating, the crystal structure is denser and it is not easy to produce oxidation.
5. Because the gold plate only has nickel gold on the pad, so it will not produce gold wire and cause it to be short.
- Because the gold plate has only nickel gold on the pad, the solder joint on the line is more firmly bonded to the copper layer.
- The project will not affect the spacing when making compensation.
- Because the crystal structure formed by immersion gold and gold plating is different, the stress of the immersion gold plate is easier to control, and it is more conducive to the binding processing for the bonded product. At the same time, because Shenjin is softer than gold plating, the gold plate is not wearable.
- The flatness and standby life of the Shenjin board are as good as the gold plate.
(3) What is the whole plate gold plating?
Generally refers to [electroplating gold], [electroplated nickel plate], [electrolyzed gold], [electric gold], [electric nickel 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 syrup, immersing the circuit board in the plating tank and applying current to form a nickel-gold plating on the copper foil surface of the circuit board, and the electro-nickel gold is coated. The high hardness, wear resistance and non-oxidation characteristics are widely used in electronic product names.
(4) What is chemical immersion gold (sinking gold)
A chemical oxidation-reduction method is used to form a coating layer, which is generally thick, and is a kind of chemical nickel gold layer deposition method, which can reach a thick gold layer, which is usually called immersion gold.
(5) the difference between them
- The difference between gold-plated plate and immersion gold plate: In the actual trial process, 90% of the gold plate can replace the gold-plated plate with the immersion gold plate. The poor weldability of the gold-plated plate is his fatal deficiency, which also causes Jiali Chuang to abandon the gold-plated plate. direct cause! In the process of use, because of the small conductivity of gold, it is widely used in contact roads, such as key plates, gold finger plates, etc. The fundamental difference between gold plate and gold plate is that gold plating is hard gold and gold is soft gold. .
2, the appearance difference: gold plating will have electric gold lead, and the gold is not. And if the gold thickness is not high, it is a method of using gold, such as: memory strip PCB, its PAD surface is a method of gold. TAB (Golden Finger) has the use of electricity and also uses gold!
3, the difference between the production process: gold plating like other electroplating, need to be powered, need a rectifier. It has a wide variety of processes, including cyanide-containing and non-cyanide systems. The non-cyanide system has a citric acid type, a sulfite type, and the like. Used in the PCB industry are non-cyanide systems. Gold (chemical immersion gold) does not require electricity, and gold is deposited on the surface by chemical reaction in the solution. They have their own advantages and disadvantages. In addition to power-on and power-off, the battery can be made very thick, as long as the time is extended, it is suitable for bonding boards. The opportunity for the disposal of electric gold syrup is smaller than that of gold, but the electric gold needs to be turned on, and it is not suitable for special fine lines. Gold is generally very thin (less than 0.2 microns) and gold is low in purity.
- The Shenjin board and the gold sheet are the same kind of craft products. The electric gold plate and the flash gold plate are also the same kind of craft products. In fact, it is only different from the different people in the PCB industry. The gold plate and the gold plate are more common in the mainland. Peer-styled, and the gold plate and flash gold plate are more common in Taiwan.
- The gold plate/gold plate is generally called the chemical nickel plate or the nickel plated gold plate. The growth of the nickel/gold layer is deposited by chemical deposition; the gold plate/flash plate is generally The more formal name is electroplated nickel gold plate or flash gold plate, and the growth of the nickel/gold layer is plated by direct current plating.
(6) The difference between immersion gold plate and immersion gold
- The crystal structure formed by immersion gold and gold plating is different. The thickness of gold is much thicker than that of gold plating. The gold is more yellow than gold plating, and the customer is more satisfied.
- The crystal structure formed by Shenjin and gold plating is different. Shenjin is easier to weld than gold plating, which will not cause poor welding and cause customer complaints. The stress of the immersion gold plate is easier to control, and it is more conducive to the processing of the binding for the bound product. At the same time, because Shenjin is softer than gold plating, the gold plate is not wearable.
- The immersion gold plate only has nickel gold on the pad. The signal transmission in the skin effect is not affected by the signal in the copper layer.
- Compared with gold plating, Shenjin has a denser crystal structure and is less prone to oxidation.
- As the wiring becomes more and more dense, the line width and line spacing have reached 3-4 MIL. Gold plating is prone to shorts in gold wire. The gold plate has only nickel gold on the pad, so it will not produce a gold wire short circuit.
- The immersion gold plate only has nickel gold on the pad, so the soldering on the line is more firmly combined with the copper layer. The project does not affect the spacing when making compensation.
- generally used for relatively high requirements of the board, the flatness is better, generally use Shen Jin, Shen Jin generally does not appearafter the black pad phenomenon. The flatness and standby life of the Shenjin plate are as good as the gold plate.