Environmental protection PCB material selection

WDF-PCB-D-25,double-sided,wonderfulpcb.com

Surface metal layer

The industry mostly use green solder "silver copper tin" formula HASL (Sn Ag - 3.9-95.5 0.6 Cn) instead of pewter, environmentally friendly lead-free PCB surface coating layer should have high wetting liquid, smaller thermal stress, high temperature is not easy oxidation features, facilitate lead-free SMT processing.In addition, flux, a synchronization is required to adopt green HASL is poor, and they have mutual fusibility with SMT solder.

Ink

Ink on the PCB leaving include: solder resist ink, printing ink, jack inks, ink composition with plank, mainly containing resin, bromine flame retardants and curing agent, at present many brand ink has do not contain harmful, such as Japan, taizhou, the new Korean ink the sun.The choice of ink must not only conform to the requirements of environmental protection, and to withstand environmental protection lead-free SMT long time high temperature for many times, not hierarchical discoloration, peeling, crack phenomenon.

Control of lead-free materials

The management of raw materials is very important one link in green PCB production, such as tin, so long as has the lead article tin was mistakenly add pure tin bath will lead to disastrous consequences, and indirect materials such as flux residues also nots allow to ignore, specific countermeasures include: (1) establishing that the encoding rules of the halogen free lead-free materials;(2) using color logo, on the inner and outer packing printed with "green" label to be approved by IQA.(3) in the warehouse and production site, to separate storage for environmentally friendly raw materials, production site personnel to add;(4) to realize "green qualified suppliers" certification program.
The choice of lead-free process and control: the selection of lead-free PCB surface coating layer process include: Ni/Au plating, chemical immersion Ni/Au, OSP (organic run-off protection agent) chemical tin Sn and chemical heavy silver Ag.

The import of lead-free process steps

CAM design

Environmental protection engineering design of PCB is basic aspects, lead-free process after the CAM should take into account the SMT process influence on the function of the PCB.
Graphic design examples (wiring, welding area shape)
1. prevent immersion flow insert parts left, red eye diameter welding area a little bit small.
2. Prevent immersion flow QFP bridging QFP tilt 45%.A dummy welding area.
3. To prevent the soft melting chip separation illuminates the basic in the past.To make the protective film: opening near it.
Prevent substrate warp

Technology development

Process of the development and management is important link in the production of environmental protection PCB, specific countermeasures including:

(1) environmental protection and environmental protection materials do not collinear or mixed line production, such as: enhancement and finished products to clean.
(2) in the MI process of paper, with environmental protection product operators, and sign the MI confirmed its, lead-free process remind now field operation department staff.
(3) environmental protection product production facilities, tooling, visual management, with prominent logo distinguish.
(4) ink has to withstand environmental protection lead-free SMT long time high temperature for many times, so the pretreatment, substrate drying is a very important link, the printing ink after spray tin or lead free HASL SMT, the possible defects of the ink on the side of hole stripping is mainly hole, floor water residue, high temperature when inflation and make the ink and copper layer separation.
(5) solder resist ink is not allowed to add rare ze agent, which can avoid high temperature circumstances hole ink residue solvent volatilization sharply inflation caused by the blasting hole.6 HASL Cu content in the tin bath to control below 0.85%.

reliability assessment

Therefore, environmental protection PCB products reliable test compared to the environmental protection PCB, but also improved the following experiments:

(1)Solderability test.(solderability test furnace with lead-free solder environmental requirements of SMT solder or HASL consistent)
(2)thermal shock test.Condition: - 40 ℃ / 85 ℃ / 85 ℃, no crack after 3000 times.
(3)the thermal cycle test.No crack, shrinkage cavity appear.
(4)constant temperature and humidity test.Condition: 60 ℃ 90-95% RH, 500 hours, under high temperature and high humidity for a long time do not produce metal products.

For more information, pls email: wonderful11@wonderfulpcb.com

Printed Circuit Board

A printed circuit board, or PCB, is a self-contained module of interconnected electronic components found in devices ranging from common beepers, or pagers, and radios to sophisticated radar and computer systems. The circuits are formed by a thin layer of conducting material deposited, or "printed," on the surface of an insulating board known as the substrate. Individual electronic components are placed on the surface of the substrate and soldered to the interconnecting circuits. Contact fingers along one or more edges of the substrate act as connectors to other PCBs or to external electrical devices such as on-off switches. A printed circuit board may have circuits that perform a single function, such as a signal amplifier, or multiple functions.

There are three major types of printed circuit board construction: single-sided, double-sided, and multi-layered. Single-sided boards have the components on one side of the substrate. When the number of components becomes too much for a single-sided board, a double-sided board may be used. Electrical connections between the circuits on each side are made by drilling holes through the substrate in appropriate locations and plating the inside of the holes with a conducting material. The third type, a multi-layered board, has a substrate made up of layers of printed circuits separated by layers of insulation. The components on the surface connect through plated holes drilled down to the appropriate circuit layer. This greatly simplifies the circuit pattern.

Components on a printed circuit board are electrically connected to the circuits by two different methods: the older "through hole technology" and the newer "surface mount technology." With through hole technology, each component has thin wires, or leads, which are pushed through small holes in the substrate and soldered to connection pads in the circuits on the opposite side. Gravity and friction between the leads and the sides of the holes keeps the components in place until they are soldered. With surface mount technology, stubby J-shaped or L-shaped legs on each component contact the printed circuits directly. A solder paste consisting of glue, flux, and solder are applied at the point of contact to hold the components in place until the solder is melted, or "reflowed," in an oven to make the final connection. Although surface mount technology requires greater care in the placement of the components, it eliminates the time-consuming drilling process and the space-consuming connection pads inherent with through hole technology. Both technologies are used today.

Two other types of circuit assemblies are related to the printed circuit board. An integrated circuit, sometimes called an IC or microchip, performs similar functions to a printed circuit board except the IC contains many more circuits and components that are electrochemically "grown" in place on the surface of a very small chip of silicon. A hybrid circuit, as the name implies, looks like a printed circuit board, but contains some components that are grown onto the surface of the substrate rather than being placed on the surface and soldered.

Wonderful PCB (HK) Limited, with over 15 years experience of producing PCB, fabricates printed circuit boards for customers in many industries worldwide, including communications/telecom/IT, medical electronics, consumer electronics (mobile phones, computers, LED lighting, etc.), and the automobile industry. We supply high-precision, high-density, double-sided and multilayer custom PCBs and PCBA services for customers in many countries.

Multilayer PCB design method

Before designing multilayer PCB, designers need to first according to the size of the circuit, the size of the circuit board, and the requirements of electromagnetic compatibility (EMC) to determine the structure of circuit board, which is decided to adopt 4 layer and 6 layer, or the number of multilayer circuit board. Determine the layer, and then determine how electricity layer and placed within different signal on the layer distribution. This is the problem of multi-layer PCB cascade structure choice. Cascade structure is an important factor affecting PCB EMC performance, is also an important means to restrain electromagnetic interference.

The number of layers and superposition principle

Determine the cascade structure of multilayer PCB need to consider more factors. In wiring ways, layer number of the more the wiring, but plate cost and difficulty also increases. For manufacturers, cascade structure symmetry or not is the focus of the need to pay attention to when PCB manufacturing, so the layer number of choice need to consider all aspects of the demand, in order to achieve the best balance.

For experienced designers, after fulfilling the components of the preliminary layout, bottlenecks for PCB wiring place emphasis on analysis. Combined with other EDA tools to analyze circuit board wiring density; Then integrated signal such as difference lines with special wiring requirements, such as sensitive signal lines to the number and variety of determine the signal of the layer number; Then according to the requirement of the power supply, isolation, and the kinds of anti-interference to determine the number of electric layer within. In this way, the whole circuit board layer number is basic assurance.

Ms Grace Zhang 

________________________________
Oversea sales 

Wonderful PCB 

NO.32A,Building NO.1, XianDaiChengHuaTing,ChuangYeRoad   |  NanShan District,ShenZhen City 518054  |  China 

T +86-755-86229518-809 | F  +86 755 2607 3529|  e  wonderful16@wonderfulpcb.com |
w  www.wonderfulpcb.com  | Skype:wonderful16 | MSN: wonderful16@hotmail.com

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 flexible 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.

PCB production process

One,contact the factory
First, the need to contact the PCBA manufacturer, and then registered customer number, then there will be people you quotation, place an order, and follow up the production schedule.
Two, expected to open
Objective: according to the engineering data MI requirements, in compliance with the requirements of the large plate, cut into small pieces production plate. The customer request small plate material requirements.
Process: plate material, edge cutting and grinding to a board to curium plate to beer fillet \according to requirements of MI
Three, drilling
Objective: according to the project information, in accord with the requirements of the opening sheet size, aperture drill position corresponding to the request.
Process: laminated plate pin, upper plate and lower plate, hole drilling, check \ repair
Four, the copper deposition
Objective: the copper deposition is the use of chemical methods in the insulation on the hole wall deposition of a thin layer of copper.
Process: coarse grinding, plate and hanging plate, copper precipitation automatic line, dipping down% dilute H2SO4, thickened copper
Five、 image transfer
Objective: to pattern transfer is the transfer of image from film to plate production
Process: (blue oil flow): grinding plate, printing the first side, drying, printing second surface, drying,exposure to flush the shadow to check; (dry film process): Ma plate to squeeze film, static,alignment and exposure to static, Chong shadow to check
Six, pattern plating
Objective: pattern plating is in line graphics bare copper skin or a hole on the wall of the plating layer of copper layer and the required thickness requirements to the thickness of the gold nickel or tin layer.
Process: on board, degreasing, water washing two times, etching, water washing, pickling, water washing, acid leaching, copper, tin, water washing, the lower plate
Seven, stripping
Objective: plating covered with NaOH solution receded anti film makes the non line copper layer is exposed.
Process: water film: inserting frames, alkali, washing and scrubbing, machine; dry film: board,machine
Eight, etching
Objective: etching is the use of chemical reaction to the copper layer corrosion non line parts.
Nine, the green
Objective: to transfer the green is green film graphics to the plate, to protect the line and stop line tin welding parts function
Process: grinding plate, printing photosensitive green to curium plate, exposure to Chong Ying;grinding plate, Indy side - drying plate to print second surface - drying plate
Ten, character
Objective: the character is an easy to recognize markers offers
Process: the green end curium, cooling static, adjusting net, seal character, curium
Eleven, gold finger
Objective: plating requires a layer thickness in the plug on the finger nickel \ gold layer, the wear resistance is more hardness
Process: on board, degreasing, water washing two times, etching, washed two times with water, acid pickling, water washing, copper plating, nickel plating, washing, gold-plated
Tin plate (a process parallel)
Objective: spray tin in the bare copper surface not covered on the solder oil spray a layer of tin,copper surface to protect non corrosion oxidation, so as to ensure the good welding performance.
Process: Micro etching, air drying, preheating, rosin, solder coated, hot air leveling coating, air cooling, washing drying
Twelve, forming
Objective: through mould pressing or milling machine gong out of shape forming method customer needs organic gongs, beer plate, hand gongs, hand cut
Note: Data gong machine plate and punching board and precise, hand gongs secondly, hand cut board lowest with can only do some simple shapes.
Thirteen, test
Objective: through 100% electronic testing, detecting visual is not easy to find to open circuit, short circuit etc. the influence of functional defects.
Process: the die, board, testing, qualified to FQC visual inspection, unqualified to repair, back testing, OK - REJ - Scrap
Fourteen, final inspection
Objective: through the appearance defects of 100% visual inspection panel, and the slight defect repair, avoid the problems and defects in plate out.
Specific work process: incoming to view the data, visual inspection, qualified, FQA checks, qualified,unqualified and packaging, processing, check OK

How to get more and more orders from customers

In today's condition of information explosion, the business is more and more difficult. Especially in the global financial crisis period, feelings will be deeper. Therefore, in this adverse environment and more fierce competition, how to get orders is very important.
Try to improve overall quality, the higher of the overall quality, the more appealing.
We often encounter a situation: on the same question, someone will find very excellent answer, his clarity, logic, feasibility are all above the crowd. Why? Because of the high overall quality. Therefore, We must pay attention to learning, attention to the accumulation of experience, attention to learn from the experience, pay attention to constantly improve our self-serving to speak and act. As the saying goes: "do business must first learn how to be a good man",  in fact, it is not only integrity, more important is to have a high ideological and cultural taste. So when in contact with the customer, it will make people feel your outstanding, they will admire and believe you before do business with you. Thus, after several contacts and then the customer and you will tend to become friends, and slowly became "buddies child." Then there will be a lot of business after that.
Written by Shirley Xia from Wonderful PCB company

Printed Circuit Board

   Single side pcb
Single-Sided Boards we have just mentioned, at the most basic PCB, parts focused on one side, the wires are concentrated on the other side. Because the wire only in one side, so we call this PCB is called a single panel (Single-sided). Because there are many single panel strict limits on the design line (because only one side, and between the wiring alone can not cross * path must be around), so only the early use of such a circuit board only.
  Double-sided pcb
Double-Sided Boards This board has wiring. However, to use the wire on both sides, must be between the two sides have the proper electrical connections for the job. This circuit between a "bridge" called pilot hole (via). The guide hole in the PCB, metal filled or coated with a hole, which can be connected to the wire on both sides. Because the double-sided single-panel area than twice as big, and because the wiring can be interleaved with each other (you can go around the other side), it is more suitable for use in more than one panel
  Mulity layer PCB
[MLB] plywood when more complex application requirements, can be arranged in a Multilayer PCB structure and pressed together, and in the inter-layer connectivity provisioning through-hole circuit layers of circuitry. Inner line CCL first crop to fit the size of the production process. Before first use the substrate film usually requires brushing, micro-etching method such as a copper foil to make the appropriate plate surface roughening treatment, and then the appropriate temperature and pressure to the dry film resist is attached on the adhesion. After the polymerization reaction will produce a good dry film photoresist substrate paste into UV exposure machine, exposure, photoresist film by ultraviolet radiation transmittance in the region (the region will be dry later developed, copper etching step is retained as an etch resist), and the line image on the film over to the dry film photoresist on the board. Remove the protective film after the surface of the membrane, the first area of the membrane to the surface of the aqueous sodium carbonate developer removing unlit, mixed with hydrochloric acid and hydrogen peroxide solution out of the exposed copper is removed by etching to form a line. Finally, mission accomplished with aqueous sodium hydroxide wash dry film photoresist removed. For the six (or more) of the inner layer circuit board with automatic positioning punching machine out of the inter-layer circuit alignment riveting reference hole.
Sophie Deng
_______________________________________
Wonderful PCB Limited
NO.32A,Building NO.1, XianDaiChengHuaTing,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: 9J35, HK Global sources Oct.12-15th,2013 Asia World-Expo, Hong Kong
2.Booth: 70206, CES  2014  Jan,8th-11th in Las Vegas, USA