PCB Repair

As we know, PCB Is customized product. Manufacturers produce PCBs based on customer’s Gerber Design. No matter how good electronic contract manufacturers become at producing ever-smaller and more complex circuit boards, every now and then, a defect  will be produced. In batch production, maybe it will not be a major issue. Due to it’s common when a certain small percentage of loss is expected. However, in a small order even sample order, what if the circuit board is unique? In this case, you could be looking at huge costs to recreate it, or even larger costs if you move forward anyway. To resolve these fails, it uses a PCB repair service.

PCB Repair Process:

1. Repair

When a component which was working has failed and you don’t know why, commonly this is the most common reason you might need to use repair service. Luckily, electronics experts can analyze both the original schematics and the resulting board to discover the underlying problem. Often, it's something as simple as a single broken bit of circuit wiring or a single failed component that can be fixed for far less than it would cost to recreate the board.

2. Rework

Sometimes, it's the initial design that's flawed. A capacitor cannot handle the charge it needs, or a particular computer chip proves to be incompatible with the board. In this case, PCB board repair services can take a look at the original design specs, compare them to the finished product, and uncover which component(s) are causing the issue.
From there, it's a relatively simple matter to find suitable replacements which can meet your original specifications.

3. Modification

Or, perhaps your PCB works, but just not quite up to par. Perhaps it fails to meet a necessary requirement, such as FCC feedback shielding standards. If this is the problem, much as with rework efforts, your PCB repair service can take the working design and improve on it so it meets your needs.

4. The Protection Process

Finally, there is the highly important process of making sure all of those components can work in extreme conditions. A special type of coating is either done by dipping the components into a solution or spraying them, allowing the coating to protect the entire board from extreme heat, cold, possible corrosion or leakage, and even helps prevent shortages should condensation accumulate.

Concluded, as the development of PCB repairmen, the defects of PCB are decreasing in the finished production. Of course, it may cost some more time to find out these problems and repair them. But all we do are for better quality and better functions of PCB.

How to communicate with customers in the trade show

From the perspective of the show, and effective communication is the marketing staff at the show to keep in touch with potential customers, timely introduction of the company's products to customers in an efficient way. Then, at the show, exhibitors how to communicate with clients?
Trade show gathered a large number of products and businesses, to make your business and products in the industry come to the fore, so the most important thing is to highlight the "different" then customers will keep your products in mind.
As for differences, how to do "different" in front of the complex show to win a highly efficient communication, exhibitors should pay attention to what?
An important purpose of exhibiting companies is through the exhibition face to face communication directly with customers. But even professional exhibition, customers come to the exhibition are different: there are technical personnel, procurement staff, and is responsible for collecting market information and intelligence officers. For technical staff, most want to know the latest progress in the development of products and price points; procurement staff, looking for suppliers is their main purpose; but intelligence officials said the aim is to collect the latest research and development programs, product performance and other information, to do a comparative analysis to help enterprises for production research and development.
Because different customers have different focus, then for different customer inquiries, we need to sent suit personnel to communicate with them, will be able to increase their satisfaction. Therefore, enterprises must make adequate preparations in advance, such as product information, product quotations communicator card and so on.

Following will be continued in next chapter.
Shirley Xia
Wonderful PCB
P +8613480796172
e  wonderful25@wonderfulpcb.com |
w  www.wonderfulpcb.com  | Skype:wonderful-pcb02

Aluminum board process-C

5.9.2 precautions:
A.by board member of the board must pay attention to check, for no good grinding can take to mill again, for chafed can pick out those with sand paper (2000 #), sand flat after grinding plate.    
B. in a discontinuous production condition, must strengthen the maintenance, to ensure clean, tank cleaning.   
5.9.3 must be confirmed by the captain after Aluminum circuiy board surface has been handle, can only flow down.   
5.10 impact
5.10.1 edge with both hands, pay attention to the aluminum surface protection.    
5.10.2 aluminum plate forming die adopts high-grade beer board, and punching and shape a rushed or separate, impact, in accordance with the requirements of the MI must be placed after a piece of white paper on the surface of the aluminum plate.
5.10.3 impact should strengthen the inspection, pay attention to the don't fall green oil and chafed board face.   
5.10.4 no washing board at the time of the final inspection, the board, board with board between every good white skin.
5.10.5 every flush plate factory mold with a brush to clean again. 
5.11 final inspection: according to the IPC comprehensive enterprise standard and so on for each test.   

5.12 the packing  
5.12.1 different period, different packaging material number plate should be classification.    
5.12.2 when packing, please put moistureproof paper insulation and bead, and in the smallest package labels model indicating the version number, after the production cycle () a month for a cycle, etc.
6. About the final inspection chafed, oxidation of aluminum board's final inspection rework method caused by in the process of production of oxidation and flower aluminum plate, rework processing as follows.    
6.1 aluminum surface oxidation of aluminum plate: first line up the aluminum plate and emissions in the desktop, the cover line with welan and compaction, and then a few welan with double-sided adhesive, with a piece of light copper stick on it, the same to compaction, and then you can get a deburring machine on grinding plate.Note that before the grinding plate must turn off the pickling and put this section of the road wheel with tap water rinse clean to prevent pollution of acid tin, or directly from pickling after washing section into the aluminum base face up, only to open the above grinding brush, after grinding plate, such as oxidation phenomenon, can be ground again.Good grinding plate monolithic monolithic, put in grinding machine drying on the drying period, place 5 ~ 10 min, also can be put on the tray in white paper, take to the oven drying, 100 ℃ by 5 ~ 10 min, be careful not to take to forming washing machine to dry, because of its low temperature, it will bring aluminum surface oxidation.  

6.2 aluminum surface brush flower aluminum plate:
6.2.1 aluminum surface slightly brush flower aluminum plate, according to the aluminum surface oxidation 6.1 rework method.
6.2.2 aluminum face serious chafed aluminum board, first of all, use 2000 # sandpaper will wipe brush flat take place, and then use 4000 # sandpaper gently brush again, then 6.2.1 aluminum surface oxidation of aluminum plate rework method for processing.

Printed Circuit Board Words

01、基准尺寸：reference dimension
02、参考尺寸：reaerence dimension
03、直接量定尺寸：direct dimensioning
04、基准图：datum feature
05、基准边：reference edge
06、导线设计距离：design space of conductor
07、导线设计宽度：design width of conductor
08、中心距：center to center spacing
09、线宽/间距：conductor width/space
10、节距：pitch
11、精细节距：fine pitch
12、层：layer
13、层间距：layer-to-layer spacing
14、边距：edge spacing
15、外形线：trim line
16、截面积：crossection area
17、真实值表测量：truth table test
18、准确位置：true position tolerance
19、精确位置：accuracy
20、精确位置误差：cumulative tolerance
21、精确度：accuracy
22、累积误差：cumulative tolerance
23、焊垫：footprint
24、外层：external layer
25、内层：internal layer
26、接地层：ground plane
27、接地层隔离：ground plane clearance
28、电压层：voltage plane
29、电源层隔离：voltage plane clearance
30、电源层：power plane, bus plane
21、导通网络：basic grid
22、导通网格：track grid
23、导通孔网格：via grid
24、连通盘网格：pad (land) grid
25、定位偏差：positional tolerance
26、对准靶标：bornb sight
27、梳状图形：comb pattern
28、对准标记：register mark
29、散热层：heat sink plane
30、端接:termination
Sophie Deng
_______________________________________
Wonderful PCB Limited
NO.32A,Building NO.1, XianDaiC hengHuaTing,ChuangYeRoad|NanShan District,ShenZhen City 518054|  China  T +86-755-86229518-806 | F  +86 755 2607 3529|  e  wonderful08@wonderfulpcb.com |
w  www.wonderfulpcb.com  | Skype:wonderful-07   |                                                   
Welcome to our trading shows:
1.Booth: L32,Expo Electronic 2013,Apr.10-12th in CROCUS EXPO,Moscow,Russia
2.Booth: 11J36, HK Global sources  Apr.12-15th, 2013 Asia World-Expo, Hong Kong
3.Booth: 9J35, HK Global sources Oct.12-15th,2013 Asia World-Expo, Hong Kong
4.Booth: 70206, CES  2014  Jan,8th-11th in Las Vegas, USA

About PCB manufacturer

1.Drilling and electroplating
If production is a multilayer PCB, and containing buried hole or blind hole, each layer board must be bored with first plating before bonding. If you don't pass this step, then can't connect each other.
After by machine equipment according to the requirements of drilling borehole Kong Bi inside must go Through electroplating (Plated Through Hole technology, Plated - Through - Hole technology, PTH).After Kong Bi internal make metal processing, can make the internal lines of each layer can be connected to each other. Before starting the electroplating, must first clear hole of sundry. This is because the resin epoxy compound after heating will produce some chemical change, and it can cover internal PCB layer, so need to clear out. Remove and electroplating movements will be completed in the chemical process.

2. Multilayer PCB pressing
each single layer must be pressing to make sandwich plate. Pressing action including adding insulation between the layers, and fastened to each other. If there is through several layers of guide hole, then each layer must be repeated. A multilayer wiring on the outside of the two sides, is often only after a multilayer pressing processing.

3. Treatment resistance welding layer, surface screen printing and gold finger plating
Next resistance welding paint coverage on the outermost wiring, so the wiring will not come into contact with the outside plating parts. Screen printing surface is printed on it, to mark the location of the various parts, it will not be able to cover at any wiring or gold finger, otherwise may reduce solder ability or the stability of the current connection. Gold finger parts usually gold plating, which, when inserted into the expansion slot to ensure high quality of the current connection.

4. Test
to test whether there is a short circuit or open circuit PCB can use optical or electronic means testing. Optical methods using scanning to find out the defects of each layer, electronic testing is usually with fly needle detector (Flying Probe) to check all the connections. Electronic testing in search of short circuit or open circuit is precise, but the optical test cans more easily detected incorrect gaps between the conductors.

Aluminum PCB board Application

Led aluminum board thermal conductivity
Led aluminum pcb board and thermal conductivity aluminum board in the middle of the insulating layer (generally is PP, now has a thermal conductive adhesive, etc.), it is one of the three major measure of aluminum plate quality, heat resistance and pressure value is another two performance).Aluminum plate thermal conductivity can be tested after plate bonding instrument tests data, the high value of thermal conductivity is generally ceramic, copper, etc., but due to the cost into consideration, is currently on the market mainstream electronic aluminum plate, aluminum plate thermal conductivity of the corresponding is parameters of people's concern, the higher the coefficient of thermal conductivity is one of the symbols of the better performance.

Led aluminum plate classification
Led fluorescent lamp aluminum plate is aluminum plate classification, street light aluminum plate, tube light aluminum plate, wall lamp aluminum plate, shoot the aluminum plate, energy-saving light aluminum plate, electrodeless lamp aluminum plate, aluminum board, ceiling aluminum plate, wash wall lamp aluminum plate, the ball bubble lamp aluminum plate, tunnel light aluminum plate, floodlight, aluminum plate, aluminum plate, wall lamp high-power aluminum plate, small power aluminum plate, guardrail tube aluminum plate, neon lights aluminum plate, corn lamp aluminum plate, the candle light aluminum plate, absorb dome light aluminum plate, kitchen lamp aluminum plate, corridor lights aluminum plate, buried lights aluminum plate, dared light aluminum plate, industrial and mining lamp aluminum plate, aluminum plate bridge lights, floor tile lamp aluminum plate, stair light aluminum plate.

LED aluminum plate insulating layer
LED aluminum plate insulation layer is one of the most core technology of aluminum plate, the main adhesive, insulation and thermal conductivity of the function.Aluminum base board insulation is a power module.
Structure of the largest thermal barrier.Insulation heat conduction performance, the better, the more conducive to the spread of the heat produced during the operation, will be conducive to reduce the operating temperature of the device, so as to improve the module of power load, reducing the volume and prolong life, improve the power output, etc.
LED aluminum plate
1, audio equipment: input, output amplifier, balanced amplifier, audio amplifier, preamplifier, power amplifier, etc.   
2, power equipment, switching regulator ` DC/AC converter ` SW regulator, etc.   
3, communication electronic equipment: high frequency increase ` filtering electrical ` transmitting circuit.   
4, office automation equipment, motor drives, etc.    
5, automobile, electronic regulator ` igniter ` power controller, etc.   
6, a computer: CPU board ` diskette drive ` power supply device, etc.   
7, power module, inverter ` solid relay ` rectifier bridge, etc

High PCB Design----Wonderful PCB (hk) Limited

In the field of telecommunications , the design is very complex , the transmission speed in the transmission of application data , voice and image of the
Has been far higher than 500Mbps, people in the communications field in pursuit of higher performance and faster to launch production

Goods, and the cost is not the first. They will use more board layers, sufficient power and ground planes, any problems that may arise in the high-speed signal lines will be implemented using discrete components match. They have
SI (signal integrity) and EMC (electromagnetic compatibility) experts to simulate and analyze the wiring before each
an internal design engineers follow strict design requirements. So the field of communication design engineers through
this design is often used excessive speed PCB design strategy.

Home computer motherboard design area is the other extreme, the cost and effectiveness above all , the design
Teachers are always using the fastest, the best , highest-performance CPU chips, memory and graphics processing module technology
To form increasingly complex computer . The home computer motherboards are usually four shelves , some high-speed PCB

Design technology is difficult to apply to this area , so engineers in the field of home computers generally have adopted over
Research methods to design high-speed PCB board, they are designed to fully study the specific circumstances of those who truly resolved
The existence of high-speed circuit problem.

Repairing printed circuit boards - tips by Exception PCB

PCBs, or printed circuit boards, have revolutionised the electronic industry; however they lack the robustness of the earlier, steel-chassis, hardwired equipment, driving them to be much easier to crack. Restoring a circuit board needs a particular level of analytical ability, along with the skill to handle each element in the correct way.

Without having a thorough knowledge of the way a circuit board works, experts from Exception PCB express that diagnosing the trouble will be a problem. For PCBs that are especially complex, you might also need an oscilloscope to discover signals at different points, so as to discover the section which is creating the problem. Once this component has been discovered, it will then have to be replaced. Here, Exception PCB provides you with a brief guide on how to do this.

As outlined by Exception PCB, with the majority of passive (and occasionally active) components, a similar, as opposed to an exact copy of the broken element can be used as a replacement. You will find, for example, several unique versions of voltage regulators available, and one version can easily be swapped for another in a PCB. However, broken active components that have a very specific function (for example, audio amplifier chips) must be replaced with an exact copy.

After you have acquired the right replacement, you'll have to place the PCB on a flat surface for the fix. Exception PCB says that you might use tape to stick the board on both sides to the surface, to ensure that it doesn't move whilst you are carrying out the replacement. Pull the damaged component off the board very delicately, using tweezers. Next, switch on your soldering iron and set it to about 400 degrees Celsius.

Take some copper wire and put it on the pads of the PCB where the component was, and use the soldering iron to heat it. Wonderful pcb that any surplus solder remaining on these pads could be absorbed by the copper. Get in line the leads of the replacement component with the board's pads, taking a look at to make sure that the element is aligned as it needs to be. Then, use the soldering iron and the solder to join the leads with the corresponding pads on the board. 

Flying Probe test

Flying Probe test is to test some of the major problems of electrical latest solutions. To replace it with a probe needle bed, a plurality of motor-driven can quickly move the probe with the Rigid-flex pcb devices of the pin contact and electrical measurements. This instrument was originally designed as a bare board, also requires sophisticated software and program support; has now been able to effectively simulate the online test. Flying Probe Test appearance has changed the test method and the low yield rapid conversion (quick-turn) assembled products. Used to take weeks to develop a test a few hours now, and greatly shorten product design cycles and time to market.

Rapid test development; low cost test methods; flexibility fast conversion; well as in the prototype stage to provide rapid feedback to the designer. Therefore, comparing the traditional ICT, Flying Probe test by reducing the time required to make up for the total test time. Flying Probe test system using the benefits outweigh the disadvantages. For example, during assembly, such a CAD system file received after the start of production hours. Therefore, to test the prototype circuit boards for several hours after assembly, not like ICT, high-cost test development process and fixture may be delayed a few days or even a few months. In addition, due to the simple and quick setup, programming and testing, in fact, the general assembly of technical personnel, and not an engineer, you can operate the test. Flying Probe test also exist the flexibility to do a quick test errors quickly convert and process feedback. Also, because the test does not require flying fixture development costs, so it is a typical testing process can be placed in front of the low-cost systems. And because Flying Probe Tester change and rapid test method to convert low-yield assembly, testing usually takes a few weeks to develop a few hours you can get now.

Automatic optical alignment system and the traditional combination of flying machines, the entire automatic optical alignment can make flying more convenient testing and flying in the image processing software dedicated to digital cameras with the help of more accurate. In the traditional Flying Probe test machine, the installation of Flying dedicated to digital cameras and the corresponding image processing software; flying probe testing throughout the automatic identification and detection of the corresponding position to make flying safe and fast test. Having regard to the requirements for fast and precise flying machine, solid industrial hardware and graphics hardware choice, you should first take into account the lightweight, industrial, optical distortion-free, high-speed image processing algorithms; such testing in the actual process of flying because the industry does not appear to affect the hardware itself, the weight of the test accurate, does not appear lost step, and does not affect the image processing algorithm speed flying probe test.

China PCB industry

1. International PCB manufacturing and electronic assembly of south China show held in Shenzhen

Recently, 2014 PCB and electronic assembly of south China international exhibition was held at Shenzhen convention and exhibition center, exhibition area of 4.5 square meters, more than 500 exhibitors. Family idea for chemistry, Mr. Kang, nc, Hitachi chemical industry well-known enterprises such as, samwo international, Olympus all exhibitors.


The Hong Kong association for PCB Zhong Tai is strong, the exhibition held a series of wonderful live events, including the industry communication, open golf championship game, manual welding, etc. In addition, the exhibition this year also added new activity - "2014 PCB and electronic assembly industry conference". Meeting around the "2015 China PCB industry facing opportunity and challenge", "development trend of electronic manufacturing industry", "Japan's PCB industry status" issues, such as for the industry provides a good opportunity for learning and development opportunities.

2. Handheld PCB APP: China PCB enterprise transformation for the first time

Twenty years ago, China's PCB industry by means of introduction of foreign advanced equipment, technology development. In 2002, China became the world's third largest base of production of PCB circuit board. In 2012, the world famous Prismark PCB market analysis agencies, according to a report in 2012 global circuit board output value of $54.31 billion, while China PCB output value of about $21.63 billion, accounts for about a third of the world total.

So far, China's PCB industry from scratch, since the childhood, got rapid development. Into the era of mobile Internet, along with the continuously go deep into big data and mobile Internet technology continuously penetrate all walks of life, the development of Chinese traditional enterprise is facing a big reshuffle. In order to win a place in the increasingly competitive market, the traditional industry with mobile Internet era of transboundary cooperation development is the trend of The Times, China's PCB industry is no exception.


At present, China has many PCB industry leading enterprises have been carried out with the mobile Internet cross-border cooperation handheld circuit board mobile application development. And compared to explore traditional route how to grope for out of the palm circuit board PCB industry development, many wait PCB enterprise personage more curious is handheld circuit board bring to the whole industry development?

China Circuit Board Analysis

The report firstly introduced Printed circuit board(PCB) basic information included Printed circuit board(PCB) definition classification application industry chain structure industry overview; international market analysis, China domestic market analysis, Macroeconomic environment and economic situation analysis, Printed circuit boards(PCB) industry policy and plan, Printed circuit board(PCB) product specification, manufacturing process, cost structure etc. then statistics Global and China key manufacturers Printed circuit board(PCB) capacity production cost price profit production value gross margin etc information, and Global and China Printed circuit board(PCB) capacity production market share supply demand shortage import export consumption etc data statistics, and Printed circuit board(PCB) 2009-2014 capacity production price cost profit production value gross margin etc information.

Nowadays, the high technology products such as cells, LED lights, TVs release new product kind often. With the high technology improves, there will come out new product time to time. Most of high technology products concerns about the electric products, which will lead to the bigger request for the PCB products. In general, I think PCB is a promising product.

The demand for smart phones and touch screen tablets are the major drivers of this industry. Another significant driver for this industry is the demand for products with features that are more advanced and that offer greater convenience. The frequent technological changes occurring in the electronic market, together with the demand for new products, are among additional industry drivers.

China has become the country that enjoys the largest circuit board output value and the fastest growth speed, and also the main driving force to promote the development of the global PCB industry. In 2012, there were 791 PCB enterprises with above designated scale in China with the market scale exceeded CNY 250 billion.

 In 2013, as the cost of copper declining, the upstream industry like copper clad laminate manufacturers can directly benefit from the decrease of cost of copper. For downstream industry like circuit board manufacturers, can also reap a little less profit from it. But the increasing cost of components will directly influence PCBA industries. Therefore, the prospect of the whole circuit board industries may not be defined as flourishing or not up to now.

According to “Information Industry Science and Technology Development “11th Five-Year” Plan and Long-term Planning Framework in 2020”, circuit board (especially multi-layer, flexible, flexible-rigid and environment-friendly circuit board technology) is one of the key fields in China’s electronics information industry over the next 5 to 15 years.

Printed circuit board industry in China mainland will maintain rapid growth in the next three years. The rapid development of the domestic 3G industry as well as the rise of electronic terminals such as smart phones, tablet PCs, green base station, will have a strong pulling effect on circuit board, driving the growth of circuit board industry. In 2016, the output value will reach USD 48 billion in China, accounting for 49.4% of the global circuit board output value.

Prototype PCB Necessity and Benefits(2)----Wonderful PCB (hk) Limited

These printed circuit boards prototypes are checked in all critical conditions as everything must be checked and every problem must be solved before the production. Again, the leads and traces are re-measured so that it meets the required thickness. The VIAS and holes need individual programming for each board and their making process is also sophisticated. The tolerances and electrical signals are tested even after the addition of the surface components.
When all the components are added and it is made as the specification, it is finally tested for several times for the required result. The board must also be able to provide proper reliability and effectiveness. In this time, the board is tested without planting it in the environment it is made for. And all steps are recorded. 
And when it meets the standard quality, it is sent for production. But if any wrong occurs, it is tested again and sent for further solution. Even sometimes the whole design is changed for the failure in tests.
The prototype is made by the companies to check their products and inventions before manufacturing. And thus it helps a great deal in the development of PCB.

Electroless Copper Plating

Metallization is required on the wall of the drill holes to make them conductive. It can be done by chemical deposition or direct metallization. For double layer boards, chemical deposition is common. It is an electroless process because the deposition of copper is done in the absence of electrical current. The objective of the electroless copper plating process is to deposit a very thin layer of copper over the entire surface of the copper cladding and on bare hole walls. This layer should be thick enough to allow the electrical current during the subsequent electrolytic plating. Normally, a thickness of 0.001 Mil to 0.0025 Mil is acceptable for further electroplating at low start current. The thickness of the PTH will be increased to the required level after the electrolytic copper plating.

Several proprietary solutions are available for making electroless copper. Basically, a precious metal palladium is being used as an activator to provide a site for the adhesion of electroless copper. Electroless copper bath contains an alkaline chelated copper reducing solution that deposits thin layer of copper on activated surface.
The thickness of electroless copper needed can be observed from the following table which gives the thickness of copper foil on Aluminum pcb. For reliable operation, PTH wall thickness should be around 0.7 Mil to 1 Mil.

Electroless copper plating process is consists of 4 baths; acid predip bath, activator bath, postactivator bath and electroless copper bath. Most of the process can be done at room temperature. We'll use PTH process chemicals from Enthone-OMI as an example. Circuitprep 3023 is used to prepare the acid predip bath. It is a low acid solution to replace a bath of high concentration hydrochloride acid. An immersion for 1 - 2 minutes in Circuitprep 3023 is sufficient to attain balance in the activator bath. The preparation of this bath is simple, 100% concentration is needed. It should be noted that no water should be allowed from this bath onward until the PTH process is completed.

The next bath is the Circuitprep 3316 palladium catalystic process. Major ingredients are palladium chloride and hydrochloric acid. This is a catalyst for electroless deposition on insulators. This process should provide uniform void-free metal coverage in holes and good electroless copper to copper clad adhesion.

The next bath is the Circuitprep 4044 postactivator process. Working in conjunction with CP3316, CP4044 accelerates the initial deposition of copper onto an activated surface. Mechanical agitation is required to ensure the removal of air bubbles in the holes and a complete wetting of the PCB. The active ingredient is fluoboric acid. It remove the protective stannous from the CP3316 so that electroless copper can adhere to the activated surface easily.

Enplate CU-406 concentrates are used for electroless copper disposition. Heater is normally required in electroless copper bath. The solution itself is highly unstable and we made use of its thermal property to restrict the displacement of copper from the solution. Thus, depending on the formula, temperature can be used to control the process so that it won't precipitate all the copper when the solution is idling. In fact, a cooling coil can be installed in the bath to cool it down to around 12 ° C to save it for a longer period in time.

Introduction on flux and Tin paste for PCB assembly

FLUX
A. The function of Flux
1. Remove the oxide on the surface of part and substrate
2.Reduce the surface tension of the solder and promote the flow of the solder
3.To protect the surface of the metal, avoid it to be oxidized under the environment of high temperature.

B. The main ingredients of flux
1.Rosin: it is refined from the grease of pine tree.
2.surfactant : Because of the gentle characteristics of rosin, it is not easy to remove the oxide, thus must add surfactant in order to enhance its effect.
3. Solvent: Dissolve and blend solid state material like rosin and surfactant, general multi-purpose isopropyl alcohol or ethylene glycol.
4. In addition, there are interface active agent, foaming agent and other ingredients

C. Variety of PCBA manufacturer.
(1) Rosin flux :
1. R grade : Inactive rosin flux
2 . RMA : Weak activity rosin flux
3 . RA : Strong activity of rosin flux
4 . RSA : Super Strong activity of rosin flux

(2) Synthesis of active flux : This kind of flux is developed by DUPONT company, it’s advantage is can make the residue which caused after soldering can become liquid state, easily for cleaning.
Based on activity, it can be divided into: 
SR–No active synthetic flux
SMAR – Weak active synthetic flux
SSAR – Strong active synthetic flux
SAR – Super strong active synthetic flux

(3). Water-soluble flux: The flux of organic acids, performs best help on welding, but must pay attention to the cleaning situation of the base board of welding after washing. If there’s residues, it will cause corrosion of substrate material, military and aerospace industry are banning the use of water-soluble flux process of substrate

(4). Disposable flux
Rosin kind improved flux: solid content 5-20%, residues will not cause corrosion to the base plate.

Low content of solid flux: solid content at 5%,  disposable flux disposable because its residue in the residues of substrate could not cause corrosion of substrate, but solid content in about 5% of the flux its residue is too much less than the flux with solid content of 5-20%, so if product with high requirements on cleanliness and appearance, you must use the solid content at 5% disposable flux.

TIN PASTE
(5). VOC-FREE disposable flux :
Does not contain volatile organic solvents of disposable flux, the above all flux contain volatile organic solvent, the solvent flammable (dangerous). Not easy to control (quality) is volatile harmful to human body and the environment (toxic), in order to avoid such problems, so developed the pure water as the solvent of disposable flux.
(1).The main ingredients of Tin solder paste
Tin powder: Can realize the electrical conduction between parts and base board, and can joint the parts and boards.
Flux: compromise the tin powder and other solid substance into paste.
Its main ingredients are as follows:
A.Solvent : mix all flux element into homogeneous liquid thickens.
B. Flux : can prevent the PCB board surface to be oxide again after welding, and can pack the surfactant to improve the SIR, to enhance the trustworthiness of the base board.
C. Thixotropic Agent: avoid separation of powder and flux, and improve the printability of tin and protect tin from collapse.
D.Active agent: The main function is to eliminate the solder joints and lead oxide substrate, common active agent is: organic ammonia hydrochloride, ammonia, organic acids, etc. 

(2). Kinds of Tin Paste
1 . Water type of Tin paste: Use water to clean the flux residue on PCB board                    Water temperature 50 – 60 degree,
water pressure 2 – 3 kg / cm 2 ,
Water low: 11 – 15 l / min
2 . Resin type of Tin paste:
a . Use solvent ( CFC or HCFC Cleaner ) to clean the flux residue on PCB board.
b . Because resin kind substance does not dissolve in water, using saponification agent to make it become the material which can be soluble in water,  then use it to clean the flux residues on board.
c . Semi-wash, use EC – 7R Axarel 32 to clean the flux residue on PCB board.
3 . Free wash kinds Tin Paste : no need to be cleaned after soldering.



Ms Grace Zhang
________________________________
Oversea sales
Wonderful PCB
A Floor 6, Nanyuan Fengye Mansion, Nanshan Avenue, Nanshan District, Shenzhen City 518054, China

T +86-755-86229518-809 | F  +86 755 2607 3529|  e  wonderful16@wonderfulpcb.com |
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FPC soldering Technology

Should adopt mandatory infrared reflow furnace hot air convection, so the temperature on the FPC can evenly changes, which reduce the generation of bad welding.If using a single side tape, because it only fix the four edges of FPC, because in the condition of hot deformation, the middle part of bonding pad tends to tilt, molten tin (under the high temperature of liquid tin) will flow to generate empty welding, soldering, tin beads, make the process defective rate is higher.

1) temperature curve test methods:
    Due to the Heat absorptivity is different to the load Flexible pcb , difference type of components on FPC, the difference of their temperature rising speed after heated during reflow soldering, have different heat absorption, so carefully set reflow furnace temperature curve will bring great influence to welding quality. Relatively reliable method is, according to the plate spacing during actual production, put two sheet of the load board which with FPC in front and behind of the test board, at the same time, the FPC on the load board sticked with components, with high temperature solder wire to weld the test temperature probe onto the test points, at the same time use high temperature resistant tape to fix the probe wire onto the load board. Note that high temperature resistant tape can not cover the test point. Test point should be adopted the solder points which near the load board edges and the QFP pin, in this way the test result can better reflect the real situation.

2）Setting of the temperature curve：
During furnace temperature debugging, because the average warm to FPC is NG, thus it's best to adopt heating/insulation/reflow temperature curve method, so that each area’s parameter is easy to be control led, others, influence of heat shocks to FPC and other components will be smaller. Based on experience, the best temperature will be dispatched to the lower limit of solder paste technical requirements value, wind speed of furnace is generally adopt the minimum wind speed, chain of reflow furnace’s stability should be, can't have.

Conclusion: When doing SMD mounting on FPC, the top importance is to realize accurate positioning and fixation, the key for fixation if to make an appropriate load board, and the second importance is the prebaking, tin printing, mounting and reflow soldering to FPC. Difficulty to FPC soldering is obvious higher than to rigid PCB. so it is necessary to accurately set the process parameters,at the same time, strict production process control is also important, must ensure that operators strictly implement each regulation on SOP, engineer who track the line and IPQC should strengthen the inspection,  Discover the unusual situation of production line in time，with line engineers and IPQC inspection should be strengthened, timely discover the unusual situation of production line, analyze the reason and take the necessary measures so that can control the FPC SMT production line NG rate within scores of PPM.

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