Keyword: PCB manufacturer，gold-plated PCB，gold board PCB，PCB printing， PCB problem
The characteristics of the gold plated
As the IC integration is higher and higher, IC feet more close. And hard to turn into a tin injection for vertical thin solder leveling, this brought difficulty to SMT SMT; Another tin plate for life (shelf life) is short. And gold-plated look good solve these problems: 1 for SMT process, especially for 0603 and 0402 subminiature table, because the welding plate flatness is directly related to the quality of the solder paste printing process, play a decisive influence on the back of the welding quality and flow, so the entire board gold-plated in high density and subminiature process often seen in the table. 2 in the development phase, the influence of factors such as components procurement is often not the board to the welding immediately, but often have to wait a few weeks or even months before use, inactive life of gold plated board (shelf life) than lead tin alloy King long a lot of times so everyone is willing to adopt. Besides, gold-plated PCB in degrees of the cost of the sample stage compared with pewter plates.
However, as the wiring is more and more close, line width, spacing into the 3-4 mil. Therefore has brought the gold silk short circuit problem:
As the signal frequency is higher and higher, signal caused by skin effect in coating conditions on the quality of the signal transmission in the more obvious:
Skin effect is to point to: high frequency alternating current, current will flow tends to focus on the surface of conductor.
According to the calculation, skin depth related to frequency:
Gold-plated board other shortcomings in the difference between the heavy gold plate and gilded plate has been listed in the table.
The characteristics of heavy gold
To solve the above problem of gold plated board, use heavy gold board PCB basically has the following characteristics of BR > 1, the crystal structure formed by the heavy gold and gold-plated, zedoary will are golden more yellow than a gold-plated, customers more satisfied.
2, due to the heavy metal and crystal structure, which is formed by the gilded zedoary more easily than a gold-plated welding, won't cause bad welding, cause customer complaints.
3, only because of the heavy gold plate welding plate nickel, gold, skin effect in the signal transmission in copper layer will not affect the signal.
4, due to the heavy metal crystal structure more compact than a gold-plated, not easy to oxidation.
5, only because of the heavy gold plate bonding pad on the nickel and gold, so will not produce micro short into gold.
6, only because of the heavy gold plate welding plate nickel and gold, so on a line of resistance welding and copper layer combining with stronger.
7, engineering will not affect spacing when compensate.
8, formed by the heavy gold and gold-plated crystal structure, the stress of the heavy gold plate is easier to control, with the state of products, is more advantageous to the state of processing. At the same time, it is because of heavy gold than gold plated soft, so heavy gold plate do gold finger not wear-resisting.
9, heavy gold plate smoothness and stay in life just as good as gold plated board.
The difference between heavy gold plate VS gold-plated board.
Actually gold plating process is divided into two kinds, one is electric gold-plated, one for heavy gold, for gold plating process, its big discounts on the tin effect on, On the gold and tin effect is relatively better; Unless manufacturers requirements is dependend now most factories will choose zedoary Process! General common surface treatment as the following: under the condition of PCB plating (electric plating, heavy gold), silver plated, OSP, spray tin, lead and lead-free), These mainly for FR - 4 or CEM - 3 plates, such as paper makings and way of surface treatment rosin; Bad tin solder bad () on this if you exclude the solder paste patch manufacturer production and materials such as technological reasons, I here only the needle Said to PCB problem, has the following several reasons BR > 1, the PCB printing, PAN, whether there is oil leakage on the membrane surface, it can block the effects of tin on; This can do bleaching tin test to verify.
2, PAN, a run on a no comply with the design requirements, namely when welding plate design can guarantee enough spare parts support role! , Did
3, welding plate is polluted, it can use the ionic contamination test results;
The above three points is basically consider key aspects of the PCB manufacturer.
The advantages and disadvantages of several ways about surface treatment, is each have strengths and weaknesses!
Gold-plated aspect, it can make the PCB for a longer time, and by the changes in environmental temperature and humidity is small (relative to other surface treatment In general), can save a year or so of time;
Tin surface treatment second, OSP again, these two kinds of surface treatment in the environmental temperature and humidity of the storage time should pay attention to many, in general, large Some manufacturers will tell save between three months to six months.
Heavy silver surface treatment is a little different, the price is high, the preservation conditions are more strict, need to use paper without sulfur processing! In the three and save time Month or so!
In tin effect on ways, zedoary, OSP, tin is similar, such as factory mainly consider value! In addition to raw Production products to conform to the requirements of the local government to the final consumer, there (such as the European Union RoHS, etc.).
Source: //www.seekic.com
