Gold Finger PCB

Edge connector with Nickel plating (Ni) and gold (Au), suitable to wear style application for a full-featured product and customized quote. Tied using industry standard protocols allow electric plating nickel plating and the African Union in the etching.

With your Au selection, a standard 30-degree bevel will be added to your edge connector. We can also bevel at 15 or 45 degrees upon request. For multi-layer boards please insure adequate inner layer back set for the bevels. Gold Finger is the memory and the memory slots on the connection between the parts, all the signals are transmitted through the finger to. Gold finger by numerous golden composed of conductive contacts, but also because of its gold-plated conductive surface such as a finger-like arrangement of the contacts, so called "Gold finger." Gold finger is actually in the CCL through a special process and then covered with a layer of gold, because gold is very strong antioxidant activity, but also very strong conductivity. But because of the expensive price of gold is currently more memory are used instead of tin from the 90s of last century began to spread solder material, the current motherboard, memory and graphics cards and other devices "Gold finger" are almost always used tin material, only some high-performance server/workstation accessories will continue to use gold-plated contact point approach, the price of natural cheap.

Finger edge connectors are usually inserted into the mating groove to ease the connector. When this happens, the heart of the aircraft may be exposed copper if they do not quit this advantage fully. We will take you back to the inner layer of copper is higher than shown on the right in order to avoid exposure to copper in this location. Copper can cause direct exposure to all terminals short connector into it.

Wonderfulpcb is an experienced Aluminum pcb,Flexible pcb,Rigid-flex pcb,Multilayer pcb,PCBA manufacturer,PCB board manufacturer,provide various of printed circuit boards at competitive prices

Aluminum board process-A

the production of aluminum pcb specification
1. Preface: with the development and progress of electronic technology, electronic products to the light, thin, small, personalization, high reliability, muti_function change has become an inevitable trend.And out of aluminum plate conform to this trend, the product with excellent heat resistance, machinability, dimensional stability and electrical performance in hybrid integrated circuit, automobiles, office automation, high-power electrical equipment, power equipment, and other fields has been widely applied in recent years.Aluminium base copper clad by Japanese sanyo company first invented in 1969, our country began in 1988, development and production of Edna, developed and mass production began in 2000 in order to adapt to the mass production, mass production, artificial this production specification.     
2. Scope: this production specifications for the production of aluminium base copper clad introduces the whole process and specification, to ensure that the board in our production smoothly.    
3. Process: cutting and drilling→ dry film optical imaging→check board→etching→ corrosion inspection→solder mask→character →green inspection→ HASL→aluminum surface treatment→impact→final inspection→packaging→shipment   
4. Note:    
4.1 aluminum sheet is expensive, should pay special attention to the standardization of operation in the process of production, put an end to scrap phenomenon caused by the non-standard operations.   
4.2 each working procedure is operated operators must take put down gently, in order to avoid the plate and aluminum surface clean.
4.3 operators, each process should try to avoid hand contact with aluminum plate, the effective area after spray tin and process the board shall hold the edge, only when it is strictly prohibited to finger directly touch the board inside.
4.4 aluminum board belongs to the special board, should cause district attaches great importance to each process and its production supervisor, foreman, personal quality, guarantee the smooth plate in the process of production.    
5. The special production process flow and parameters:   
5.1 material cutting
5.1.1 strengthen incoming inspection (must use aluminum sheet metal surface has a protective film).
5.1.2 without baking plate after cutting.
5.1.3 light to take light put, pay attention to the protection of the aluminum surface (protective film).
 5.2 drilling
5.2.1 drilling parameters and FR - 4 plate drilling parameters are the same.    
5.2.2 aperture tolerance yan, 4 oz base Cu attention to control the generation of the beatles feng.
5.2.3 requires copper on the hole.
5.3 the dry film
5.3.1 incoming inspection: before grinding plate must be inspection on aluminum surface protective film, if there is any breakage, must be fastened with welan again after pretreatment.     
5.3.2 grinding plate: only on copper surface for processing.
5.3.3 the paster: copper, aluminum surface shall be sticker.
Control grinding plate and the lamination time interval is less than 1 minute, ensure the paster temperature stability.
5.3.4 clappers: pay attention to the clappers precision.
5.3.5 exposure, exposure ruler: 7 ~ 9 have glue.
5.3.6 development: stress: 20 ~ 35 psi speed: 2.0 ~ 2.6 m/min, the operator must be careful operation, avoid the protective film and aluminum chafed below.
5.3 the dry film
5.3.1 incoming inspection: before grinding plate must be inspection on aluminum surface protective film, if there is any breakage, must be fastened with welan again after pretreatment.

Global And China FPCB Industry Report, 2014

In 2013, FPCB industry enjoyed a high-speed growth with the market size approximating USD12.03 billion, up 16.2% from the level in 2012. The South Korean vendors developed rapidly and were excessively upbeat about the industry’s outlook, aggressively expanding capacity starting from the very beginning of 2012. As a result, most of new capacity was available in Q2 2013. However, the FPCB companies in South Korea without diversified customers, were heavily dependent on the key accounts such as Samsung and LG, thus making them less competitive during negotiations. Therefore, these vendors cut the prices steeply in Q4 2013, sending them into price war.

In 2014, price decline continued to deteriorate, which led to a sharp fall in revenue of South Korean vendors. The implications of high-speed capacity expansion are high fixed costs, which would thus result in a plunge in profit margin. It is projected that the revenue of INTERFLEX, a leading South Korean FPCB company, would tumble by 50%, and its operating margin would record a 27% loss in 2014 in contrast to no-profit-no-loss in 2013. Additionally, affected by the order shift of Apple, the company has hardly received any orders from Apple in 2014.

Another pressure for the vendors in South Korea came from the depreciated yen, and the won appreciated against the yen. However, the Japanese products have better performance; coupled with the reduced prices bought on by yen depreciation, they are more competitive.

Apple shortened the supply chain, giving more of its orders to the vendors in Taiwan, which resulted in a fall in revenue of M-Flex, at an estimated 20% drop in 2014. And as the losses expand, M-Flex’s operating margin is expected to slip from -8.4% in 2013 to -11.8%.

Despite a substantial decline in revenue of the South Korean vendors, the biggest customer of FPCB market—Apple did not bring down the purchase price. Meanwhile, the new iPhones have bigger size and therefore need more FPCBs. Consequently, the vendors in Taiwan and Japan saw a big increase in revenue, thereby filling in the vacuum. We predict that in 2014 the market size of FPCB worldwide reached USD12.608 billion, up 4.8% from 2013.

Of the Taiwanese vendors, ZDT generated the most revenue. ZDT under Hon Hai obtained more of the orders from Apple. It is forecasted that its revenue will jump by 55% to USD1.518 billion in 2014, overtaking Japan’s SEI as the world's second. In contrast, the world’s first NOK reduced the capacity in Japan, instead expanded the capacity in Thailand and Mainland China, which helped not only substantially increase its revenue but also rapidly turn out of red. At the same time, the global HDD market tends to be stable, with the shipments rising mildly from 2013. The HDD for FPCB is the main product of NOK, an Apple's leading supplier.

We project that in 2015 smartphones will present a slowing growth, tablet PCs will begin to decline, notebook computers will grow slightly or be flat. Moreover, LCD-TVs are expected to grow by a small margin. And wearable devices are very likely to rise significantly, but its application of FPCB is too small to fuel the market. In 2015, it is more than likely that LCD-TV will be the mainstay to drive the market. And after 6-8 years of popularization, LCD-TV is expected to undergo a boom of TV set replacement. And consumers will choose 4K TV with higher resolution or change the original smaller 32-37 inch television to 40-42 inch television.

We expect that it will be very hard for the South Korean vendors to reverse the downtrend when Samsung’s mobile phone shipments slow down and its LCD shipments are falling with losses. It is more likely that the South Korean vendors will suffer collapse, while the companies from Japan and China’s Taiwan will benefit from it, especially Japanese ones that had improved the competitiveness after the repeated depreciation of yen.

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FPC Assembly

Nowadays, technology is already very mature to rigid Printed circuit board, however, many problem may be faced by operator during SMT to FPC.
1 False soldering, short soldering,Tin beads.
2.The Reason is due to the hardness of  raw material of FPC(Flexible printed circuit) caused, FPC is out of shape when meet the hot air and high temperature in reflew machine. Lead the wave shape to FPC, and the slop to FPC pads, then cause the flow of molten tin (liquid tin under high temperature), which cause False soldering, short soldering,Tin beads.(The main reason is the hardness of FPC). So if make the hardness of FPC into the same situation as rigid printed circuit board, and all soldering problem to FPC can be solved. The condition is you should know the SMT process to PCB. And then improve the hardness of Flexible Printed circuit into with the same hardness as rigid PCB, and then FPC SMT can be realized. And some problem, like no fix hole, no mark point, or the FPC is over long, which are the fault of designer, and it is also hard to be solved even to rigid PCB SMT. And NG rate can be only reduced based on personal experience or device independence.

According to above comment, the main solution is to improve the hardness of FPC the same as hardness of rigid PCB.

B. How to realize stable soldering to FPC
How to get the stable FPC (flexible circuit board) to the rigid PCB welding effects depends on the degree of hardness.
Methods: using jigs(carrier, handling plate) to make FPC perform as rigid board during SMT.

Below is the instruction of Magnetic reflow soldering tray
The material
1. Choose imported alloy material: good flatness, stable performance under high temperature
2. High temperature resistant magnet (300 degrees) to ensure permanent magnet during reflow soldering process.
3.The special steel, with magnetic treatment and good elasticity, and no deformation under high temperature.
4.Performance
(1) Because the flatness to FPC surface cause from the steel pressure l, it can reduce the flow of solder tin during reflow, which can ensure the good quality of soldering and reduce the NG soldering at meanwhile.
(2) Ensure the life of tray when choosing tray material.   
(3) Easy and convenient operation with high stability. 
(4) Heat insulation, prevent the FPC from deformation
There’s no special requirement to the composition of solder paste of FPC, the size of the tin ball particles and the amount of metal content, etc will be subject to if there is narrow space of IC pins on FPC, BUT FPC has high performance requirements to the solder paste printing, solder paste should has good thixotropy, solder paste should be able to easily be printed , demoulding and can be firmly adhere to the surface of FPC, there will be no mold release lead the hole in stencil filled with tin or such as collapse after printing.

     Because FPC fixed on the pallet before SMT,  and the FPC with high temperature heat-resistant pressure-sensitive adhesive tapes for purpose of location, which make its planar inconsistencies, thus FPC printing surface is unlikely to be as smooth as rigid PCB and the same consistent on thickness and hardness, so operator should not use a metal scraper, and should use the polyurethane scraper which with hardness of 80-90 degree.

 Solder paste printing machine is best to be with the best optical positioning system, otherwise will have great influence to printing quality, FPC although fixed on the load board, however, there always be small space between FPC and the load board, this is the biggest difference as rigid PCB board, thus the equipment parameters’s setting will also has great influence to the printing effect.

    Printing stations is also the key location to prevent FPC from being smudgy, need to wear glove then can go ahead for operation, at meanwhile,  workstation should be kept clean, stencil should be frequently wiped to be clean, to prevent the solder paste to pollute the gold fingers and gold plated key button. 

Control of FPC SMT

According to the properties of the products, components quantity and efficiency of mounting, it is OK to adopt high-speed placement machine for SMT. Because every piece of FPC has positioning with fiducial MARK, therefore, there’s no big difference on surface mounting technology between FPC SMD mounting and rigid PCB SMD mounting. It is important to note that although the FPC are fixed on the load board, but its surface can’t be the same flatness like rigid PCB board surface, local space must  exist between FPC and load board, so, the height of suction nozzle’s dropping, compression of blowing should be exactly setted.  On other side, most bare FPC performance as panel; format, and the rate of good finished product relatively low, so it if normal that there’re part of pieces with not good quality, which request recognition function on BAD MARK to SMT machine, otherwise, when mounting FPC panel with the status of not all pieces are good, will show low efficiency. 

Multilayer PCB design method (W)

11.4.1 The Multilayer PCB design related Settings
1. Power Plane Clearance
This rule is used to set the electric layer security spacing, mainly refers to no Internet connection and the electrical layer of bonding pad and the hole and the electrical layer security spacing, as shown in figure 11 -11. At the time of manufacture, no Internet connection and the electrical layer of bonding pad in through electrical layer around the copper film is corrosion, corrosion of the size of the ring is, the value of the constraint set.

2. Power Plane Connect Style
This rule is used to set the electric welding plate and the layer forms.Mainly refers to a network connection with the electrical layer within the welding plate and the hole and the electrical connection between the form. As shown in figure 11-12.

Click the Properties button, pop-up its rules Settings dialog box, as shown in figure 11-13., the applicable scope of the rules on the left side of the dialog box to Rule the Attributes on the right side of the drop-down list to choose connection mode: Relief Connect, Direct Connect and No Connect. The Direct Connect directly connected, the electric welding plate inside through layer did not drop the copper film around the corrosion, electric welding plate and inside layer copper film directly connected;No connect to show No connection, that is, with the copper film network bonding pad of the same name will not be connected to the inside electrode layer;Designers usually use the system default Relief Connect connection forms, the rules of the Settings dialog box shown in figure 11-13.

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 |
w  www.wonderfulpcb.com  | Skype:wonderful16 | MSN: wonderful16@hotmail.com

Multilayer PCB design method (U)

(3) Delete: delete layer.  In addition to top layer and bottom layer cannot be deleted, other signal layer and internal power layer all can be deleted, but have wiring in the middle of the signal and has been integral in electricity layer cannot be deleted.  Choose the Multilayer pcb layer which need to delete, click on the button, pop up as shown in figure 11-8 dialog, click Yes button, the layer is removed.

(4) Move up: up a layer. Choose the layer which need to up (layer can be a signal layer, it can also be power layer), click the button, then the layer move a layer at the meeting, but not more than the top layer.

(5) Move down: down a layer. Similar as move up button, click on this button, this layer will move down a layer, but not more than the bottom layer.

(6) Properties. Click the button, the pop-up similar as shown in figure 11-3 layer properties dialog box.

11.3.3 Middle layer settle
Completion of the layer stack manager related Settings, click the OK button to exit the layer stack manager, can be done in PCB editor interface related operations. On the middle layer operation, need to first set up the middle layer is displayed in the PCB editor interface. Select “Design”/”Options…” Command the pop-up as shown in figure 11-9 option settings dialog box, under an Internal planes of the electricity option box only, display inner electrode layer.



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 |
w  www.wonderfulpcb.com  | Skype:wonderful16 | MSN: wonderful16@hotmail.com

Why use surface mount technology (SMT)?

Currently, advanced electronic products, especially in the computer and communications electronics products, has been widely used in SMT technology. SMD devices on year rise in international production, but production is declining conventional device, so as time goes into between, SMT technology will become increasingly popular.
So what is the advantage of SMT in circuit board manufacturing?
1,The pursuit of the miniaturization of electronic products, perforated and plug components used previously been unable to narrow.

2, The electronic product features become more complete, integrated circuit (IC) is no longer used by the piercing element, especially in large-scale, highly integrated IC, had to use surface mount components.

3, Bulk products, production automation, factory should take a low-cost high-volume, producing high quality products to meet customer demand and enhance market competitiveness

4, The development of electronic components, integrated circuits (IC) development, multi-application of semiconductor materials

5, Electronic technology revolution is imperative, chasing the international trend

SMT has become a mainstream technology in the era of high-density, due to the use of SMT technology, PCBA  also follow up and get rapid development. SMT market share surge makes more stringent, good PCBA SMT is a prerequisite for success. SMT mainly from the process to control the quality of the process. Today we will introduce single Sided SMT assembly process.

Single Sided SMT assembly process：

Incoming inspection -> screen printing solder paste (dot patch glue) -> patch -> drying (curing) -> reflow soldering -> Cleaning -> Test -> Rework

The Features to FPC

Advantage
(1) Can be freely bent, coiled, folded, may request any arrangements in accordance with the spatial layout, and can be moved and scaled in three-dimensional space, so as to achieve integration of the components assembly and wires connection.

(2) The use of flexible PCB board can greatly reduce the volume and weight of the electronic products.

(3) FPC itself has good heat resistance and weldability, and easy to be packed with low comprehensive cost advantages. The design of Flex-Rigid PCB also make up the shortage of carrying capacity of Flexible base material to components in a certain extent.

2.Disadvantage
(1)High initial cost
Due to Flexible PCB is designed and manufactured for special applications, so start cost for circuit design, circuit layout is relatively higher. Unless there is special demands to apply for flexible PCB, usually FPC is not adopted for small qty demands.

(2)Difficult repair and modification for flexible PCB
Once Flexible PCB finished, if need to be double modified, should be started from the base drawing and Light painting program, so it is not easy for changing. Because there is a cover lay on FPC surface, before repairing, cover lay should be taken off first, and must be redone with cover lay after repair, this is difficult job.

(3)Limitation on size to FPC
Under the condition that the flexible PCB is not very popular, FPC usually made by intermittent method process, thus with restrictions on the size of production equipment, flexible PCB can't be made very long and wide.

(4)Improper operation easily cause damage to FPC
Improper operation taken by worker will cause the damage to flexible circuit and the soldering and rework need to be runed by specially trained operator.

Economy of FPC
If the circuit design is relatively simple, and the total volume is not big, and with appropriate space, the traditional way for internal connection is too much cheaper. If the circuit is complex, and there’s special requirement on electrical or mechanical performance, flexible circuits is a better design option. When the size and performance of the application beyond the ability of rigid PCB, flexible circuit board is the most economical. On a thin film can be made with 5 mil vias and 12 mil pads 3 mil line width and space of flexible circuits. Therefore, mounting chips directly onto the film is more reliable. These films may be protective, and cured at high temperatures, get higher glass transition temperature. Flexible material is more saving on cost compared to rigid material, the reason is out of  connector.

Structure of FPC
According to the conductive copper foil layer division, FPC is divided into single layer board, double layer plate, and multi-layer FPC. Single layer plate structure: the structure of flexible plate is the simplest structure of flexible plate. Usually base material + cellophane tape, copper foil is a set of purchased raw materials, protective film + cellophane tape is another purchased raw material. First of all, the copper foil need to be done with etching process to get the needed circuit, protective film need to be done with drilling to reveal the corresponding pad. After cleaning, then use rolling method to combine the two parts. Then to do with gold plating or plating tin on the uncovering part as protection. Then, the large sheet is ready. Generally, the bog sheet should be punched into several unit pieces with required shape an outline. Also some FPC has no requirement on protective film and directly print solder mask onto the copper foil, this way can low down a lot on cost. However, this will weaken the mechanical strength of the FPC. Unless the strength requirement is not high and the price also should be low as far as possible. But it is best to stick the protective film. Double layer FPC structure: when circuit of the circuit is too complex, single plate can’t meet the demand or in need of copper foil for grounding shield, will need to use double layer FPC or multilayer FPC. The most typical difference between multilayer and single layer FPC is there’s vias to connect the copper in every layer. The first process to multilayer FPC is making vias. First do drilling on the base material and copper foil, then cleaning and then plating with a certain thick copper, then vias finished. After above, the later process is the same as single layer FPC. Double layer FPC structure: There are pads on both top and bottom layers. Double layer FPC is mainly used to be connected with other board. Though the structure is similar as single layer FPC, however, big difference on process. It’s raw material is protective film + cellophane tape.   First do drilling on the film according to the pad location, then stick the copper foil, when the pad and circuit come out then stick another film which already with vias. Then finished.

8 Rules of PCB Design

A PCB is the abbreviation of Printed Circuit board. All the components on the circuit board are held in position by drilling holes or Pads in the demarcated areas on the board, and then soldering the components into place. The copper tracks which take the place of traditional wires are more effective and more resistant to damage. The copper tracks place a rule as link among all the components, forming a circuit underneath the board. Keeping some simple rules in mind can avoid that we have to contact you after you place an order to resolve PCB design issues.

Before PCB design, please remember 8 rules as below:

·Everything starts with the circuit design. Without a circuit there is no need for a PCB. In the old days most circuits were hand drawn and later captured electronically. In today’s world of modern computing, the circuit design is capture directly into a schematic. For the sake of clarity we’ve added this in the PCB design rule.

·Always lay out your board design on a fixed grid or a snap grid so that the components and tracks will be able to “snap into place.” It is important to use the grid to make sure you have enough space on the PCB board material for all the components and it will allow you to have fluid copper tracks rather than bits and pieces all over the place.

·Please make sure you provide an indication of the layer definitions in the copper, such as a caption: “TOP” in the top layer, “BOT” in the bottom layer.  Missing or incorrect labeling is the most frequent cause of problems, since many Layout programs permit mirrored data output! For this reason, please label your circuit boards always with TOP and BOT in the copper! Correct labeling with TOP and BOT in the circuit board’s copper provides information about the layer definition, and also for the layer orientation!

·Track sizes will vary depending on the type of board you are designing, the purpose of the board and how much conduction is necessary.  It is always possible to use different sized tracks to allow for bridging or tightly spaced tracks.

·Place each route and each component in their grid off the board then when you are sure of its position, place them on the circuit board individually in order to maximize your efficiency and reduce your margin for errors.

·Do not scale your data – Please keep all data be scale 1/1 (100 %).

·Use the same units (mm or inch) in your Gerber & Exelon output files as in your CAD PCB design software. This will eliminate conversion or rounding errors.

·Lastly, you shouldn’t be sending Eagle BRD files to board houses anyway. That leaves too many judgment calls for the board house to make. Create the Gerber files yourself, then the board house knows what to do, and you can take the files to any other board house too. Most board houses don’t want Eagle files, or charge extra for doing the conversion to Gerber for you.

CES 2015: The future of wearable technology

Flexible PCB board devices for clothing, virtual-reality contact lenses and tools to help hearing impediments are some of the futuristic use cases for rapidly emerging wearables.

"We should not be trying to make tech wearable, but rather make wearable things technology-enabled," according to Mike Bell, the vice president and general manager of Intel’s new devices group.
Speaking in Las Vegas today on a CES 2015 panel about the growth of wearables, Bell discussed the challenges manufacturers and brands in the space must overcome to break into the mainstream.
He said a "cellphone on the wrist" [the smartwatch has become the poster child for wearables] is not what people want, and wearable tech will start moving into items like jewellery and watches.
Wearable tech gets its share of bad press for a wide range of reasons, including its failure to look good and demonstrate utility for consumers. Reports have shown that current devices, such as fitness trackers, are often abandoned several months after use.
Despite the challenges the category faces, the panellists were bullish on wearable tech’s future, confident the devices are not a technology fad.
Christopher Glode, the general manager at Under Armour Connected Fitness, said: "The market valuation of wearables is not really relative to the amount of hype they get, but real markets are being created around wearables now.
"Sensors are getting smaller, batteries are lasting longer and the technology is evolving very, very quickly, piggybacking on smartphones, which means more things are possible now."
Bell added that wearable devices are more accepted these days because of the rise of smartphones, legitimising the need for consumers to have a device with them all the time.
But wearables will not replace smartphones any time soon, the panel argued.
"The phone will become even more important as a hub for experience," Glode said.
Carmichael Roberts, a partner at North Bridge, the venture capitalists, said that wearable tech would continue to innovate in the direction of something "invisible, seamless, comfortable and very personal," blurring the boundary between humans and computers.
"People won’t think about it, like they don’t think about having tattoos on their skin, like a stamp or a sticker," he said.
Limor Schafman, the founder and chief executive of GlobeShift, said the major future developments in the wearables space would be in flexible wearables that can become part of clothing, contact lenses with virtual reality and technology to help people with hearing impairments.
"There is no limit to the imagination of what is possible," Schafman said. "What is fascinating is that the technology is here. Now, what do we do with it?"
This story has been taken from Campaign US.
This article was first published on campaignlive.co.uk

Electronic Lead Free Assembly

Transitioning to lead-free assembly electronics requires not only product reliability, but also the ability for an optimized assembly process. Additionally, material selection, component changes, and handling potential testing failures are integral to a successful transition.

Choosing Materials
Surface finish is one of the key material choices impacting the entire assembly electronics process. The assembly process itself, plus the complexity of the board and its use environment, all make an impact on this decision. Typical options include lead-free HASL or ENIG, OSP, ImAg, and ImSN, with new innovations becoming market-ready all the time. Different laminates are often under-specified due to underestimating their quality during the assembly process. Alternatively, laminates may be over-specified, which commands a higher cost.

Solder alloys are another important decision: wave solder, surface mount, and solder for BGA balls all have to be considered. Typically, SAC305 is the surface-mount alloy of choice, and it performs acceptably under most circumstances. Depending on the complexity required for your wave solder alloys, the most cost effective solution is SnCU, especially if you have thin boards with low-aspect holes that need to be filled. SnAgCuNi is preferable for more challenging holes, although this may depend on the surface finish and choice of flux as well. For board flexing capabilities, or withstanding shock events, a variety of lower modulus alloys like SAC105 are becoming more prevalent.

Component Qualifications and Testing
Early adopters of lead-free assembly electronics discovered frequent occurrences of melted plastic components on wave solder connectors. This lead to a switch away from nylon 66 toward the more appropriate nylon 46, or sometimes LCP. These meet the requirements of moisture and temperature sensitivity, a must-have in surface-mount LF components.

Other components that need to withstand heat damage may be more difficult to detect, which makes preventing that damage a greater challenge. Electrolytes within electrolytic capacitors may boil if time limits and safety temperatures are exceeded, yet these limits are not always outlined in sufficient detail.

Common specs may offer some suggestions, yet without the necessary variables to predict possible behavior. Component engineers end up guessing at preheat durations and total peak heat, while attempts are made with lead-free alloys to properly fill holes under various conditions.

Testing the strain capability of separate components following lead-free assembly is another blind spot. For example, it’s commonly known that SAC alloys have a reduced tolerance for strain, yet their assembly manufacturing people rarely offer specific limits for these devices. If suppliers could record results of four-point bend testing for their components in order to determine an objective maximum strain capability, the user could know if problems are more likely to arise during component stuffing, performing ICT, or attaching their boards to the chassis.

Reworking
All too often, lead-free reworks are overlooked in favor or meeting tight manufacturing schedules. However, records indicate that reworking is one of the greatest challenges involved with making the transition to lead-free assembly. A Lead-free assembly electronic has a more difficult window lying between the cold solder on one end and heat damage at the other.

Reworking can bring operator-to-operator benefits to the mix, optimizing equipment process that was probably originally designed for Sn-Pb rework. Every critical component requires a strict rework process which must be rigidly adhered to. Extensive failure analysis has to be undertaken before a determination regarding appropriate rework procedure can be made. Damage to the PCBA manufacturer, the component itself, or any neighboring components must be prevented. New rework equipment may be necessary, as well as the employment of new shielding techniques.

Implement Auditing
Despite the growing experience with assemblage of lead-free PCBs, high quality is not always maintained after high-volume production begins. A comprehensive audit plan should be in place to address with the supplier in order to ensure accountability.  Making the change to lead-free assembly electronics provides an excellent opportunity to review your supplier’s typical process, and make any necessary adjustments for optimum quality control.

Immersion tin

For nowadays all the solder material is tin-based, the tin layer can be matched with any type of solder, In this point, immersion tin process is very promising. However years ago, Aluminum pcb will exits tin whiskers after immersion tin process and tin migration and tin whiskers shall bring reliability problems in the welding which limited the use of immersion tin process. Later we found the solution that adding tin organic additives to the immersion tin liquid which makes tin layer to become granular structure, well solved the problems, and also make better thermal stability and weldability.
Immersion tin process can form the flat copper-tin intermetallic compounds, this feature makes the immersion tin has the same good weldability as hot air leveling but without the headaches flatness problem; Also do not have proliferation issues between gold metal compared to Electroless Nickel / Immersion;
But the immersion tin plate can not be stored for a long time.

Aluminum board process-B

5.4 Aluminum pcb 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.  

System Level Design for My Bluetooth LED Lamp

System Level Design for My Bluetooth LED Lamp, yes I make Visio drawings for fun.
You may not know specifics like what supply voltages you will need or what connections need to be made, but you will be able to consider how each component will rely on the others and what additional components they will add to your design.
This is also a good time to consider the aesthetic aspect of your design. Are you trying to fit a certain form factor? Do you need to consider ergonomics (for example if you are designing a game controller)? Will you be able to pick up your design a year from now and understand exactly how it works? These are the types of details Aluminum pcb, while seemingly insignificant, can be the difference between a good design and a great design.
I know all this talk of visualization may sound cheesy and like it won’t really get you anywhere, but I assure you it is worthwhile. If you don’t want to believe me, consider this quote from Nikola Tesla’s autobiography where he describes his creative process:
My method is different. I do not rush into actual work. When I get an idea I start at once building it up in my imagination. I change the construction, make improvements and operate the device in my mind. It is absolutely immaterial to me whether I run my turbine in thought or test it in my shop. I even note if it is out of balance. There is no difference whatever, the results are the same.
Of course the vast majority of us aren’t at the level of crazed genius that is Tesla, but the idea behind this method is all the same. By visualizing your design beforehand you save time, money, and frustration.
Following will be continued in next chapter.
Shirley Xia
Wonderful PCB
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Drilling in Printed Circuit Board

A circuit board drilling is just like a common drill, except that it is optimized for drilling holes in the printed circuit board as opposed to drilling holes in other materials such as wood. Holes are normally drilled in circuit boards which made from tungsten because of its mechanical properties. Another difference of circuit board drilling from wood drilling is that, the size of this type of drill can vary greatly because it typically is very small. Sometimes, this drill is made by people, but it more often is combined with a drill press for automated drilling by the machines.

There are two main drilling holes in the circuit board. One is NPTH hole, another is PTH hole. All the holes in the single sided printed circuit board are NPTH hole. That’s because no need for electronic conduction between layers in single sided PCB. It has just one copper foil layer. PTH hole will appear in double sided or multilayer PCB.
These holes exist for the electronic conduction among layers. So it may have Copper in these holes.

While as explained, circuit board drilling holes must be very small. We usually use unit mil to indicate it. What’s more tungsten is a very hard metal. So circuit board drilling holes are made by drill bits. The PCB drill bits are made of micro grain carbide. They are used primarily in CNC machines for drilling printed circuit boards for electronics, but their toughness and accuracy lend them to uses in other industries. When a hole has to be drilled through a circuit board, the bit must go through copper traces, which are sturdy and hard. That’s a subtle work. A piece of printed circuit board may have several thousand of drilling holes including NPTH and PTH holes, so many PCB boards are finished drilling by machines!

One thing we should pay attention to is the smear when drilling holes in a PCB. For multilayer boards, those with three layers or more, drilling typically produces a smear of the high temperature decomposition products of bonding agent in the laminate system. We should remove the smear before plating through these holes. So we need to have a chemical de-smear process, or plasma-etch. The de-smear process remove smear to ensure that a good connection or electronic conduction among layers when the holes are plated through. If smear remains in the PTH holes, it may cause short cut in the printed circuit board. Some bad PCB products are rejected just because the smear of the holes!