PCB surface treatment: anti-oxidation, spray tin, lead-free spray tin, immersion gold, Shen tin, Shen silver, hard gold plating, the whole board gold-plated, Goldfinger, nickel palladium Gold OSP: cost better, good solderability, storage Harsh conditions, short time, environmental protection technology, welding is good, smooth.
Spray tin: spray tin plate is generally multi-layer (4-46 layer) high-precision PCB model, has been a number of large domestic communications, PCB computer, medical equipment and aerospace companies and research units can be used cheat (connecting finger ) Is the memory module and the memory slot between the connection components, all the signals are transmitted through the cheat.
Gold finger by the many golden conductive contacts, because of its surface gold and conductive contacts arranged like a finger-like, so called "cheat." Gold finger is actually in the CCL through a special process and then covered with a layer of gold, because the strong antioxidant gold, and the conductivity is also very strong. But because of the high price of gold, the current more memory are used to replace the tin from the last century, 90 years began to spread the tin material, the current motherboard, PCB memory and graphics cards and other equipment, "Goldfinger" is almost always used Tin material, only part of the high-performance server / workstation accessories contact points will continue to use the practice of gold-plated, the price is not cheap.
With the IC integration is getting higher and higher, IC feet are more and more dense. And the vertical spray tin process is difficult to fine into the pad flat, which SMT to the placement of the difficulty; PCB the other spray tin plate life (shelf life) is very short. While the gold plate just solved these problems:
1, for the surface mount technology, especially for 0603 and 0402 ultra-small surface paste, because the pad flatness directly related to the quality of solder paste printing process, the quality of the subsequent reflow to play a decisive impact, so the whole board Gold is often seen in high density and ultra-small surface mount processes.
2, in the trial stage, by the component procurement and other factors are often not the board to immediately on the welding, but often have to wait a few weeks or even a month to use, PCB gold plate life expectancy (shelf life) than lead Tin alloy long times many times so we are willing to use. Besides gold-plated PCB in the sample stage of the cost compared with the pewter alloy plate is almost the same.
But with the wiring more and more dense, line width, spacing has been to 3-4MIL.
Thus bringing the problem of short wire: With the signal frequency is getting higher and higher, due to skin effect caused by the signal in the multi-coating transmission of the signal quality of the more obvious.
The skin effect refers to: high frequency alternating current, current will tend to focus on the surface of the wire flow. According to the calculation, skin depth and frequency.
To solve the above problems of gold-plated plate, the use of Shenjin plate PCB has the following characteristics:
1, due to immersion gold and gold plating formed by the crystal structure is not the same, Shen Jin will be golden gold is more yellow than gold, customers are more satisfied.
2, due to immersion gold and gold plating formed by the crystal structure is not the same, Shen Jin is more easy to weld than gold, will not cause poor welding, PCB causing customer complaints.
3, because the sink plate only gold on the pad, the skin effect of the signal transmission is not in the copper layer on the impact of the signal.
4, due to Shen Jin gold-plated crystal structure is more dense, not easy to produce oxidation.
5, because the gold plate only gold pad on the gold, PCB so it will not produce gold wire caused by short.
6, because the sink plate only gold on the pad, so the line of solder and copper layer of the combination of more solid.
7, the project in the compensation will not have an impact on the spacing.
8, due to immersion gold and gold plating formed by the crystal structure is not the same, PCB the Shenjin plate stress easier to control, for a bonding of products, the more conducive to the bonding of processing. But also because the gold-plated gold than gold, so the gold plate to do the gold finger is not wearable.
9, Shen gold plate flatness and life expectancy and gold plate as good.