Do you really know Multilayer PCB?

WDF-PCB-M-34,6 layer,wonderfulpcb.com

Most materials systems used in PWBs (aka PCBs) are composites of resins, fabric substrates and metal cladding. Each of these components has its own unique electrical and mechanical properties that contribute to the final characteristics of the finished laminates, prepregs and fabricated multilayer boards (MLBs). In most cases variables such as glass style and resin content have offsetting impacts on physical vs. electrical properties.

Data sheets often provide data in standard IPC formats, which may look at properties in rigid laminates (nominal 0.062” made using heavyweight glass at 32–40% resin content) rather than thin lams and prepregs used for multilayer PWBs (which more typically average 55% resin content or more). To further complicate the situation, some product lines are manufactured with consistent resin content for all product thicknesses, thus maintaining the dielectric properties while letting the mechanical properties be dictated by the constructions and resin content.

An understanding of what such variations in properties mean and how they relate to what the users will actually encounter is essential to design, manufacturability, assembly and end-use viability. In this presentation we will look specifically at the effect of glass style and resin content on dielectric constant and CTE and discuss how even at the product design  level it is important for design engineers to take these into consideration.

Conclusions

In most cases, no single value of dielectric constant or in-plane CTE (representative laminate properties that are impacted by resin content variation—obviously there are others as well, but for purposes of keeping this work manageable, we will focus on these two) will hold for all thicknesses of laminate or build-ups for MLBs. In those cases where either or both are critical, it is necessary to control resin content in both laminate and prepreg to ensure that the finished properties fall within the desired and expected ranges.

In some cases, such as with 85N polyimide and 92ML thermally conductive epoxy products, the specific values of Dk and CTE are less critical than other things such as processibility and design flexibility (as for 85N) or thermal conductivity (for 92ML) and so resin contents are allowed to vary so as to meet these needs.

In other cases either CTE (as in 85NT) or dielectric constant (as for Multiclad HF or 25N/FR) are critical needs, and in those cases the resin contents must be held to controlled limits so that the desired properties are consistently held for most or all of the laminate configurations.

Environmental protection PCB technology

Since the eu formally in December 2003 after "lead-free" legislation, the global electronic has great impact, in July 2006, the European Union WEEE directive about scrap electrical and electronics equipment, electrical equipment on restricting certain pollution substances in the ROHS directive and the Japanese association for the advancement of electronics industry (JEIDA) and the national electrical manufacturers association (NEMl) about the lead, the halogen electronic packaging industry has come into effect, the market of electronic products not contain lead, mercury, cadmium, hexavalent chromium, and restrict the use of polymeric brominated diphenyl or brominated flame retardants, PBB, PBDE harmful substances, such as this will impact of the global supply chain operations, including PCB industry and the development of relevant industries.My company to research environmental protection PCB products since 1999, and became one of the earliest recognized global green partner manufacturers Japan panasonic, and environmental protection and is now 99% PCB products are resonant.In this paper, from the raw material control, the choice of lead-free process and control and SMT electronic encapsulation after three aspects, comprehensively expounds how the next generation of PCB products to meet the increasingly stringent environmental requirements.

The selection and control of raw materials
As is known to all, in the PCB industry, mercury, cadmium and hexavalent chromium are almost don't have to, or in addition to containing trace, in the process of wet process will not be deliberate use of PCB manufacturers, so in the choice of raw materials and process, as long as considering the lead Pb and halogen don't overweight can conform to the basic requirements of environmental protection, metal processing is in be lead-free PCB surface (< 0.1% Pb), the traditional PCB and SMT industry, due to the extensive use of lead, tin alloy, such as HAL, solder paste, etc.Lead is a heavy metal elements, is widely distributed in nature, is the three elements of radioactive uranium and thorium, the end product of the decay of actinium, once the body of the lead intake more than its saturation concentration, can appear the symptom such as anemia, calcium deficiency, weakened immunity.Why do you want to lead-free solder?Leaded solder harmful: lead in solders for the soldering is 1% of the total usage weak (30000/5 million tons), and have widely spread the possibility of difficult to fully recovery.Due to environmental pollution, anxiety, such as lead poisoning effect on human body.In the PCB industry, halogen (fluorine, chlorine Cl, Br Br, 1 F) application mainly on the plate and ink.

material choosing
PCB processing eventually formed on the finished product, mainly includes three types of material: plate, surface processing (metal) layer and ink.1.1.1 plate regular plank FR - 4, CEM - 3, because contain a large number of brominated epoxy resin, such as four bromine bisphenol a, polybrominated biphenyls (PCBS), polybrominated diphenyl ether, etc., in the process of combustion, emit high toxic substances, such as dioxin (TCDO), such as benzene, furan, once the intake will not be able to discharge by human body, greatly threatening the human health.So the PCB must be halogen-free copper clad industry base material chlorine (Cl, Br Br is less than 0.09% respectively), phosphorus (P) epoxy resin instead of brominated epoxy resin, with nitrogen (N) phenol to replace the traditional dicyandiamide curing agent.
In addition, the environmental protection plate also has the strong heat resistance, able to lead-free SMT engineering under 260 degrees high temperature for many times, do not change color, stratification, deformation and bending.

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

Aluminum board process-B

5.4 board inspection
5.4.1 line surface must be in accordance with the requirements of the MI to check all the content.
5.4.2 must check on aluminum surface, aluminum surface dry film cannot have film falls and broken.
5.5 etching
5.5.1 for copper base is commonly 4 oz, will there is a certain difficulty in etching.First plate must be approved by the captain in person to do board, made in the spot check, line width, line spacing should be strengthened once every 10 PNL plate spot check line width, and make records.
5.5.2 recommended parameters: speed: 7 ~ 11 dm/min pressure: 2.5 kg/cm2 proportion: 25 be temperature: 55 ℃ (the above parameters are for reference only, the test plate results shall prevail)
5.5.3 back membrane should be paid attention to the time of the control between 4 ~ 6 min, because aluminium will reaction with NaOH, but also must ensure that the membrane clean, backing down membrane liquid membrane was not allowed to turn up the heat.No protective film of the plate, aluminum, from liquid membrane in the back up after the board will not stay to wash water on a board in time of liquid membrane, prevent the alkali corrosion of aluminum surface.  
5.6 corrosion inspection
5.6.1 normal board.
5.6.2 it is forbidden to use the blade repair line, in order to avoid injury and dielectric layer.
5.7 the solder mask
5.7.1 production process:
Brush copper surface grinding plate (only) to screen printing green oil (the first), and preliminary drying screen printing green oil (second) and the preliminary drying - exposure and development - plate mill, the acid pickling process. Under the soft brush - after curing -
5.7.2 reference parameters:
5.7.2.1 yarn used 36 t + 100 t
First 75 ℃ 5.7.2.2 x 20-30 min;The second 75 ℃ x 20-30 min
5.7.2.3 exposure: 60/65 (single) 9 ~ 11
5.7.2.4 enhancement: speed: 1.6 ~ 1.8 m/min pressure: 3.0 kg/m2 (total pressure)
5.7.2.5 curing: after 90 ℃ * 60 min + 60 min + 110 ℃ 150 ℃ above x 60 min parameters for the use of the DSR - 2200 tl ink, used only for reference.
5.7.3 note printing for control of air bubbles, if need, can add 1-2% of the diluent.
5.7.4 clappers before clappers member should check panel, there is a problem of instruct the captain and then to the clapper.   
5.8 HASL
5.8.1 spray before tin for aluminum plate with protective film tear protective film after spray tin.    
5.8.2 edge with both hands, it is strictly prohibited by hand directly touch the plate (especially aluminum surface).
5.8.3 operation, fight chafed.
5.8.4 tin cookie sheet before 130 ℃, 1 hour, and baking sheet to spray tin interval time less than 10 minutes.In order to avoid temperature difference cause a layered with ink.    
5.8.5 rework plate spray is only allowed to return once, if more than one board, to distinguish for special treatment.    
5.9 aluminum surface passivation treatment
5.9.1 level passivation process: (1) scrubbing brush (500 #) to (2) water - > (3) passivation, (4) washing the x 3-5. Dry - 6 drying
Note: (1) grinding plate: only aluminum surface grinding, FR4 parameter grinding plate.First board to check line no scratches, as well as the tin cried, uniform grinding crack.
(3)passivation: potion ingredients open cylinder quantity cylinder volume liquid temperature control concentration spraying in tank pressurization rate
Na2CO3 (CP) 50 g / 6500 g l, 130 l, 40 ~ 50 ℃ 2.0 ~ 3.0 1.0 ~ 1.5 m/min effective soaking time 10 ~ 15 s 100 m2 CP (K2CrO4) 15 g/l,  1950 g NaOH (CP) 390 g, 3 g/l
6 drying: 80 ~ 90 ℃.
Tyle = "the oledata.mso - spacerun: 'yes', the font size: 10.5000 pt; the font-family:" tahoma "; "> 5.7.2.5 curing: after 90 ℃ * 60 min + 60 min + 110 ℃ 150 ℃ above x 60 min parameters for the use of the DSR - 2200 tl ink, used only for reference.
5.7.3 note printing for control of air bubbles, if need, can add 1-2% of the diluent.   
5.7.4 clappers before clappers member should check panel, there is a problem of instruct the captain and then to the clapper.  

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Flex PCB - What is Flex PCB

FPC and the birth and development of the PCB, Rigid-Flex PCB gave birth to this new product. Therefore, Flex PCB is flexible circuit board and rigid circuit boards, after lamination processes, according to the relevant process requirements together, forming characteristics have FPC PCB board characteristics.

1.Flex PCB - Production Process：

Because Flex PCB is a combination of FPC and the PCB, Flex PCB production should also have the FPC PCB production equipment and production equipment. First, the combination of soft board electronics engineer to draw a line and shape according to demand, then, can be issued to the Flex PCB production plant, through CAM engineers relevant documents for processing, planning, and then arrange FPC production line production need FPC, PCB production line to produce PCB, after these two soft board and hard board out, according to the planning requirements for electronic engineers, the FPC and PCB through seamless lamination lamination machine, and then through a series of detailed links, ultimately process the Flex PCB. A very important aspect should Flex PCB difficult, more details before shipping, are generally required to conduct the inspection, its value is relatively high, so as not to let the supply and demand sides related loss of interest.

2. Flex PCB - Advantages and Disadvantages：

Advantages: FPC Flex PCB along with features and characteristics of the PCB, so it can be used in some special requirements of the product among the region has some flexibility, but also have a certain rigidity region of the internal space-saving products reduce the volume of the finished product, improve product performance is very helpful.

Cons: Flex PCB production process many, difficult to produce low yields, cast materials, manpower more, so its price is more expensive, relatively long production cycle.

3. Flex PCB - Related Applications

Flex PCB's characteristics determine its application in all areas covered by FPC PCB applications, such as:

1.Mobile telephone

2.Keypad and side buttons, etc.

3.Computer and the LCD screen

Such as motherboards and display

a.CD Walkman

b.Drives

c.NOTEBOOK.

4. New Uses

Components of a hard disk drive (HDD, hard disk drive) suspension circuit and xe packaging board, etc.

PCB material appearance defects common measures and industry analysis of commonly used terms

The reason PND (Pits and Dents) pits and depressions occur: fish  any fines particles adsorbed by the edges due to static electricity, the upper plate  residual water Material of the active air drop of dust and debris attached to the copper plate. Solution: identify the problem immediately to re-grind plate and, after washing on the line of the most fundamental solution to reduce staff contact and exposure to air time, to complete the clean room stacked combination of cutting and automatic installation of devices to eliminate static electricity.

  SLP (Slippage) slip occurs:   piece of content R / C high and  flow R / F is greater than the pressure is too easy to produce timely, and every pot temperature is too large and cause uneven flow  substrate per pot Chan will lead to poor positioning piece slip responses: Chan piece R / C, R / F high vertical machine (or water Liquidation machine) can also alter the conditions on Chan laminated CYCLE such as reduced heating rate as amended, postponed the pressure, reduce stress, if a larger temperature difference between each pot can reduce tension lowering capacity to overcome the poor pay more attention to improving the positioning operation.

  Dry (Dried Laminate) board dry Analysis: Poor glass cloth coupling agent compatibility with resin resulting in poor wetting. Or  piece over so that timely pressure hardening resin flow is bad if found to have low flow  board that will produce dry, this condition at the time of solder measured 詴 prone stratification. Solution: glass cloth surface finish problems, please materials manufacturers improved  low traffic reduces varnish water  of time or improve  piece   flow of time and, if not serious Dry Lamination may amend conditions such as increased temperature rate, the pressure on early, increasing pressure. 

PCB Prototype Assembly Creates Unique Boards

PCBs are important part of all electronic equipment that is used these days. The layout and design of a PCB is crucial for the entire product. This key element or components can define product’s success as well as failure, because this is what the product performance is dependent on. In the meantime, if pcb assembly make any mistakes such as wrong assembly, absent assembly etc, will occur big problem in product’s function!

Most (although not all) of firms only provide manufacturing services, so it's entirely on you to provide specifications for a quality device and to hope they are able to deliver it. If the specs were flawed, or if counterfeit parts sabotage it, there will be little you can do about it. Wonderful PCB Technology Co., Ltd is PCB manufacturer and has PCB assembly line in house, which provide you whole services of PCB! Wonderful PCB provide high quality PCB assembly prototype, which can often save you a lot further down the road.

The Benefits of PCB Prototype Assembly

Think of it as an insurance policy: If you spend a bit more money up-front, you'll save yourself a lot of hassle later on. After all, these days, you can't risk your company's reputation on dodgy electronics. Once a firm becomes known for poor products, it can be extremely hard to undo the damage without a full (and costly) rebranding effort.

With PCB prototype assembly services, you get the breathing room you need to thoroughly test your design before committing to a production run.

As an experienced electronics manufacturing Service Company, Wonderful PCB can often begin by improving your design right from the start. Many initial designs are overly-complex, or fail to take advantage of the latest manufacturing technologies on offer. Allowing the manufacturer to look over your design and suggest changes can very often result in simplified designs that reduce component use, making them both cheaper and more reliable.

PCB Prototype Assembly Builds Better Boards

Simply put, prototyping services help you create a better product. You'll be able to put items on shelves which are less expensive, more reliable, safer, and more compliant with health and environmental regulations.

Given that your reputation really is all you have on the Internet, why gamble with untested products? Put a little more money into prototyping, and you'll reap the benefits throughout your products' entire life cycle.