中文版
ENGLISH
Home   |   About us   |   Products   |   Factory   |   News   |   Contact us   |   Feedback
 
    ·Products Catalog
· Hardware parts
· Infrared Remote Control
· Power Adapter
· Car Charger
· Remote Switch
· TTL Flash Synchro Cord
· Hot Shoe Converter
· Auto Extension Tube
· LED Video Light
· Colorful Photograpic Accessories
· Camera UV Filter
· Camera Shutter
· Wifi Product
· Monopod
· Bluetooth speaker
    ·News
·Warmly celeb..
·XinRui New Y..
·The train wa..
·Several prin..
·The board in..
    ·Links
buxun
baidu
Shenzhen construction site
xinmei-technology
Google
     News
Multi-layer circuit board plating process
Addtime:2011-08-02
With the vigorous development of surface-mount technology, the future trend of the printed circuit board will inevitably move toward thin lines, small holes, multi-layer, high-density packaging type. However manufacturing such high-level board copper plating process will also be faced with some technical bottlenecks, for example: how to make the panel the central and edge uniformity of coating How to improve the the keyhole wall of distributed force, how to improve of the physical properties of the coating, such as ductility, tensile strength and are well worth the effort of topics, the purpose of this article that is based on the basic principles to explain the process where the difficulties lie and seek suitable response. personal humble opinion can be helpful for board employees. recent years, with the rapid development of the semiconductor and computer industries, the production of printed circuit boards are increasingly complex, we may be empirical formula as the degree of difficulty of judging board pointer.

Board complex procedures pointer = the number of circuit board layers * number of wires between the two solder joints / the spot pitch (inch) * wire width (mil)

(1) For example, a 16 layers, the pad spacing of 0.1 inch, wire width 5mils, two joints between three wires indicators of its complexity of 96 , the popularity of surface mount technology to drive the circuit board industry towards high-level since the 1980s, followed by multilayer forward, thus a rapid increase in the complexity of indicators rises to 100 or higher, from about 20 traditional board, in such update product evolution process, of course, inevitably encounter some technical bottlenecks, copper plating process, for example, I tried to macroscopic, microscopic and micro-structure to explore the basic principles and seeking coping strategies.

(A) macroscopic Refers

plate surface of the circuit board, usually a board the size of the board is approximately 24 "* 18", to the central and edge coating thickness uniformity is no easy task, according to the Faraday’s law of electrolysis, the coating thickness is proportional to the applied current, assuming that the density of the coating as a certain value, the distribution of coating thickness is the cathode current distribution, affecting many of the current distribution factors, including the resistance of the solution, the polarization of the electrodes, plated pieces of the geometric shape of the anode and cathode distance, plus the current size, mass transfer rapid rate, in the following sections we will discuss the impact when the current distribution on the electrode polarization or other interference factors called current distribution depends entirely on the plated slot geometry When a certain voltage is applied to the two electrodes, each point also certain of the voltage is present in the plating bath, and its size is the range between the two electrode voltage, because of the highly conductive metal electrodes, we can assume that each point of the surface of the electrode voltage to equal Similarly, in the plating bath may also find some of the imaginary plane having an equal potential, generally said, come close to the position of the electrode, such as the ground plane and the electrode shape is very similar, but its shape gradually decreased as the distance to the electrodes increase and change, Figure description of one that the distribution of the condition of the ground plane, the more intensive local current density distribution in the equipotential surface, otherwise smaller. learned by the electric field theory, and so the potential of the plane and the stress The planes are perpendicular to each other, while the electrode itself is equipotential plane, so a certain point of the current flow into or out of the electrode will be with the point where the plane is perpendicular to each other. i.e. instructions distribution relationship of the ground plane and the current flows if the equipotential plane is certain the entire conductor to replace or potential surface stress of the plane on an insulator alternative would not affect its electric field. Conversely, if such as bit-plane is no substitute for cutting off the entire farm will be equal to the degree of interference, the current distribution will change as electrodes and electrode will be the same as the current distribution of A and C as an example, A and BB, mainly due to the the BB plane happens to coincide with the equipotential surface, thus will not affect the electric field, assuming that the A and C slightly mobile, its off-center position, such as the distribution of the bit line and the original are very different impact modifiers because the electrode position of the electric field so that the current The distribution also change.

(A) 1. Change a current distribution method

By said farm basic theory that, once the current distribution is entirely dependent on the geometry of the plating tank, which is also the distance of the anode and cathode, the size, shape will affect the current distribution on the circuit board board its edge most other planes than intensive distribution, it is thicker coating and the central part of the thin To improve this phenomenon must be stressed that the concept of the design, such as increasing the anode and cathode distance, increasing the anode and the area, the use the insulation of shielding material to change the bit planes, auxiliary anode to improve the current distribution of the low current area, dispersed auxiliary cathode current high current area are feasible.

(A) 2. Secondary current distribution

Since the electrode is polarized to change a current distribution in this case, the resultant current is referred to as a secondary current distribution, first, the concept of polarization must be simple descriptions In simple terms, the polarization electrode electrochemical reaction occurs in the vicinity of increasing the resistance of the solution could successfully generate To make the desired reaction applied voltage must be increased this way, will generate additional heat and power consumption electrode voltage level dilute potential difference due to polarization effects, both of the difference is called the voltage in the vicinity of the cathode, the ions participate in the electrode reaction, consume too fast too late supplementary, this time caused by over-voltage, said To make the concentration over-voltage, ion passed some energy barrier to reach the electrode are required to participate in the reaction voltage is called activation voltage, while the total over-voltage is the concentration over-voltage and activated the sum of the voltage, is used to measurement indicators of the degree of polarization of the electrode. inversely proportional to the distance between the current size and the anode and cathode, the electric intraoperative role of representing an increase of the distance of the anode and cathode of the distance double since such effect known as the characteristic length, secondary The current more or less will be able to reduce the current uneven phenomenon.

(A) 3. Polarization parameters

Actual subject to the following two factors swayed by the foregoing basic theory learned current electric field distribution force, respectively, for the solution resistance and polarization resistance and ALKIRE once the polarization The parameter P made the following definitions.

P = R / Rp = acFLj / RgTK (2) wherein ac is the migration coefficient, F is the Faraday constant, L is the anode and cathode distance, j is the average current density, Rg is a gas constant, T is the temperature, K is the conductivity of the solution. if P << 1, on behalf of the polarization effect far exceeding the electric field effect, the current tends to secondary current distribution will be very uniform. if P >> 1, the current tends to primary current distribution depends entirely on the geometry of the plating tank, they nozzle design trouble but the drawback is unable to achieve the goal of mass production.

(B) plating tank design guidelines plated holes are too many factors involved, so that the plating tank design is quite difficult, but kessler and alkire some basic rules as a basis for the design I Reference First, they define two basic parameters N and E, N represents the average current parameter, E represents a current distribution force parameters to the physical sense, the resistance N = solution resistance / mass transfer fast arising

(4) E = solution resistance / polarization resistance

(5) If the value of N is large, on behalf of the current tends to the primary current distribution, relatively uneven, if the value of N is small, there are shown tends to limit mass transfer fast, i.e., plating deterioration of the quality, when E << 1, the polarization effect of the role of the resistor is greater than the solution the current tends secondary current distribution will be very uniform, if the E >> 1 the current distribution uniformity deteriorated, such as N and E at the same time consider summarized in the following two criteria:

(1) E <1 while the panel and a hole to obtain a uniform current distribution.

(2) N> = 64E can be reached between the two relations of the uniformity of the distribution and coating quality of the hole current balance. Micro-structure aspects of

C) high-level multi-layer printed circuit board often used as a military use, its reliability must also objects do not pay attention to the need by the U.S. military specifications such as drift tin or temperature the test cycle, the physical properties of the coating, such as ductility, tensile strength can often determine the success or failure of the test, gloss and additives play a very important role to improve the physical properties of the coating, the basic reaction mechanisms in this special simple descriptions.

(C) 1. Plating the basic reaction institutions metal ion plating with at the cathode substrate is usually divided in two steps, the first step is the solution of metal ions to the cathode movement by an electric double layer i.e. charge migration reaction, a second step is ion reaches the electrode combined with each other or with the original grain Results, together this step is called crystallization, due to the metal ions in the solution is often the number of water molecules  wrong ion is formed, the water molecules must be removed before the metal slowly ions and electrons knot together, because the surface of the substrate lattice planes of varying shapes, several of Curved planar and curved edge voids and holes, like so wrong ions to the water charge transfer reaction first plane ladder curved than directly into the location of the hole-shaped columns can save energy, As regards the formation of crystals.

(C) 2. The role of the additives in the plating so that the surface roughness is reduced or Sik the ductility of the coating often require additives or gloss agents have proposed the projections of the surface smoothness of the reaction mechanism of a section can be adsorbed more gloss agents, thus increasing the resistance, since the current is always toward the low resistance portion, so the current can flow smoothly into the coating recessed part of coarse reduced and because the majority of gloss agents to organic Bockris also proposed a theory described adsorbed on the condition of the electrode surface when the electrode itself with excess negative or positive charge, water molecules will be rendered electrically bipolar morphology of falling or rising, i.e., increase and adsorption between electrodes force this way reduce the force of the adsorption of organic molecules, whereas, if the electrode itself without charge, the rising and falling trend of water molecules cancel one another, the adsorption force is reduced thereby enhancing the adsorption of organic molecules, whereby the basic theory will be available for The different nature of the coating study its place of the additives.

(C) 3. Pulse plating affect on the micro-structure of the pulse wave plating most significant of the function is to change its way to the physical properties of the coating microstructure, many data show, in the The ductility of the coating adhesion than traditional DC pulse current is far greater, and the roughness is reduced through which institutions produce such effects? has still not very clear.

Conclusion

This paper to analyze the basic theory to macroscopic, microscopic and micro-structure of three points of view on the multi-layer printed circuit board copper plating process, the conclusions are summarized as follows: (1) on the circuit board panels, the current distribution is mainly determined by the geometrical shape of the plating tank, such as anode distance arrangement, size, etc., luster agents or additives has little influence on the current distribution. To change the current distribution uneven enables auxiliary devices such as shielding or auxiliary cathode.

(2) on the circuit board through-hole current distribution and coating properties, mainly affected by the resistance of the solution, electrode polarization and mass transfer fast complex factors To get quality distribution and uniform coating, it is bound to emphasize the design concept, for example, the application of special mixing method, the use of pulse plating technology.

(3) Additive or gloss agents may change the physical properties of the coating, such as ductility, tensile strength, etc., but if the amount of excess may also cause pollution of organic matter on the coating quality, in addition also increased management of inconvenience. pulse plating method to improve the physical properties of the coating is worth the effort to study. circuit board industry booming production ranks third in the world in the production of high-level board, however there are still a lot of neck yet to break through the future trends of the copper plating process is the use of specially designed plating tank and coupled with the quest for improvement in the chemical, in order to improve the technical level of a new bright vision.

Click:1019
 

   XINRUI TECHNOLOGY INDUSTRIAL CO.,LTD.   ©   2012  
Tel:+86-755-81782586   Fax:+86-755-81782096   Email: sales@xinrui-technology.com     QQ:2322763338
Website:www.gekk2.com  Address:1F,D building,shang pai industrial zone,bei huan road,shi yan street,bao an district,shenzhen,china.

Powered by:www.szunjian.com  buxun.net 

 

 

 

 

友情鏈接Links:星美科技  xinmei-technology 百度搜索 百度百科 360搜索 谷歌搜索  深圳網站建設 蘭翔帆布   興達防雨布  興達蓬布廠  德隆帆布  方大防雨帆布 方大篷布廠
豐翼防雨布 天悅防水帆布 深圳貝朗衛浴 深圳空氣能熱水器 廣州廠房租賃  深圳水晶禮品廠 浦江水晶禮品廠-國星水晶  浦江水晶工藝品-米蘭水晶  深圳麥軒月餅

Powered by buxun.net
奇米网狠狠网