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Shenzhen Rong Jiexin Electronic Technology Co. Ltd.

Address: Baoan District City, Xixiang Shenzhen 60

Contact person: Mr. Zhou

Mobile phone: 13825253955

Phone: 0755-29708225

Fax: 0755-29702200

Email: rjx_china@163.com

Web site: www.rjxelec.com

 
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PCB surface treatment
1, PCB surface plating treatment
With the integration of IC is getting higher and higher, the more the IC foot is more dense. And vertical tin spray process is difficult to will become thin pads blowing flat, which gives the SMT mount brought difficulty; also HASL inactive life (shelf life) very short. And the gold plating board just solved these problems:
For surface mount process, especially for 0603, 0402 subminiature surface mount, because the pad evenness is directly related to the solder paste printing process quality, on the back of the reflow soldering quality play a decisive impact. So, the whole plate gold in high density and ultra small table paste process often seen.
In the trial stage, influenced by the components procurement, and other factors often not board to the welding immediately, but often, several weeks or even months before use, the gold plate stand-by life (shelf life) than lead tin alloy. Gold many times longer so we are willing to adopt. Besides gold-plated PCB in of stage of cost and lead tin alloy plate compared with almost the same. However, with the increasing density, the line width and spacing have reached the 3-4MIL, which brings the problem of gold wire short circuit. As the frequency of signal is increasing, the effect of skin effect on signal quality is more obvious. The skin effect is the high frequency of alternating current, the current will tend to focus on the surface flow of the lead.
2, PCB surface precipitation
The crystal structure formed by gold and gold is not the same as that of gold.
Gold and gold plated with the formation of the crystal structure is not the same as the gold plating more easy to weld, will not cause welding bad, causing customer complaints.
Gold plate only has a nickel metal on the plate, the skin effect of the signal transmission is in the copper layer will not affect the signal.
The crystal structure is more compact and less prone to oxidation than gold plating.
Gold plate is only on the welding plate nickel gold, so it will not produce gold wire caused by micro short.
The gold plating on the plate only has a nickel gold, so the bonding between the solder and the copper layer is stronger.
The project will not affect the spacing when the compensation is made.
The crystal structure formed by gold and gold is not the same as the crystal structure, which is more easy to control, and is more advantageous to the processing of the state. At the same time, it is also because of the gold plating gold plating soft, so the gold plate do not wear gold.
Gold plate smooth and for life and is as good as gold plate.
3, PCB surface oxidation (OSP) treatment
Organic solderability preservatives OSP () is known as the early heat flux (preflux) in the early stage. Essentially, it is an alkyl benzimidazole (ABI for between benzimidazole) compounds, has a high heat resistance, the decomposition temperature of the general requirements in more than 300 DEG C. As a result, it can be very good to protect the fresh copper surface is not oxidation and pollution, in the high temperature welding, due to the role of the solder to remove OSP and reveal the fresh copper surface and quickly and firmly welding. But it is not suitable for many reflow soldering.
Organic welding protective agent's basic principle is alkyl benzimidazole compounds of imidazole ring can with the copper atom for 2d10 electronic form coordination bonds to form alkyl benzimidazole copper complexes. Among them, even between alkyl chain and by the van der Waals force attract each other, in fresh copper on the surface to form a certain thickness (usually for 0.3 ~ 0.5 µ m) layer of protection, plus the presence of benzene ring, so the protective film has good heat resistance and high decomposition temperature. Alkyl benzimidazole copper complex formation diagram as shown in Figure 4, which R groups (alkyl) or a combination of will determine the can as a PCB OSP use problems. The choice of alkyl (R) will affect the thermal performance and decomposition temperature of OSP, therefore, the alkyl (R) chain length and structure is the main topic in OSP research and development, and also the main contents of the continuous improvement of OSP heat resistance and improve the decomposition temperature, but also the main reason for the OSP supplier confidentiality.
4, PCB surface spray tin treatment
The so-called tin is the circuit board into the melting of tin lead, when the circuit board surface with enough tin lead, and then use the hot air pressure to excess tin lead. Tin lead after cooling circuit board welding area will be stained with a layer of appropriate thickness of the tin lead, this is tin spraying process of summary procedure. PCB surface treatment technology, most of the current application is tin spray process, also called hot air leveling technology, is in the pads sprayed with a layer of tin, with enhanced PCB pad guide pass performance and weldability. Welding quality and solder in soldering tin spraying SMOBC&HAL) as the line board processing a most common form of surface coating, is widely used in the line of production, tin spraying quality is good or bad will directly affect to follow-up on customer production; therefore tin spraying quality become circuit board manufacturers quality control of a key. For the general double plate, tin and OSP process is applied to the most, while the rosin technology is widely used in the single PCB, the gold plating process is required for the IC circuit board. Gold in the plug-in board above apply more.
In the usual PCB surface treatment, the tin plating process is known as the best, because there is tin on the pad, in the welding of tin, with the gold plate or rosin and OSP process, it is more easy. This is very easy for us to hand welding, welding is not easy.
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