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pcbcollection-blog · 7 years ago

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5 Common PCB Design Mistakes to Avoid

dvanced manufacturing techniques and innovative design tools have enabled Printed Circuit Boards (PCB) manufacturers to bring down the cost of PCBs in the past years. Many times, the cost of production increases due to errors in the PCB design. Hence, it is very important for PCB designers to avoid such fabrication errors, while designing PCBs. Read this post to know common mistakes that happen while designing PCBs, and how they can be avoided.

Common PCB design mistakes that should be avoided

Below are a few design mistakes mentioned, which a PCB manufacturer should avoid while designing one.

Over complicated designs: The basic working methodology behind the PCB fabrication helps the manufacturer develop printed circuit boards (PCBs) in the most economical and easiest way. However, an overcomplicating design may cause several problems like a schematic imbalance. This may affect credibility and productivity of a PCB designer. Hence, a designer must focus on the effectiveness of the design and must simplify it to avoid design errors.

Incorrect layout of the antenna in the wireless design: If the circuit board is using wireless technology, then a correct antenna layout is important. The impedance of the transceiver and the antenna must be matched, in order to ensure maximum power transfer. A proper transmission line is needed to connect the transceiver and the antenna. Generally, the transmission line is made with 50 ohm impedance for maximum power transfer within the antenna. Fabricators must make a special note on installing the antenna correctly in order to provide effective circuit board design.

Minimizing Slithers: Slithers are undissolved copper chunks that may stick to the circuit board during the chemical etching process. These slither may cause short circuits and several other manufacturing failures. A PCB designer should always ensure that the minimum copper width is above the manufacturer’s requirement. This helps to minimize slithers, and produce properly working for circuit boards.

Landing Pattern Errors: Libraries of electronic components are available in the PCB design software packages. Schematic symbol and PCB landing pattern for each component are a few of components included in the library. The schematic symbol and the landing pattern are to be drawn manually if the components are used outside of the libraries in PCB software design package. This may increase the probability of errors.

Decoupling capacitors: The decoupling capacitors provide stable voltage to components on the printed circuit board. They are placed closer to the pin to ensure a stable voltage. The trace powering the supply rail must pass through the decoupling capacitors before reaching the pin. If this happens, then stable voltages can be provided. Hence, the PCB designers need to utilize the decoupling capacitors effectively.

As discussed PCB layout design requires ardent precision and great technological skills. Mistakes in PCB layout can lead to huge losses. At the same time what is also helpful that a group of engineers can help to review your design before fabrication .ALLPCB.COM is a Chinese PCB manufacturer that provides top-speed PCB fabrication, Other than PCB fabrication, they also pay much attention to the customer’s design experience,they provides a big community that enables you to discuss and share projects with other engineers.You can leave your questions or confusions on ALLPCB community, and wait for reply from other professional engineers if you are a green hand in PCB design industry ,and after your design is finished, you can just order directly from ALLPCB and get your required boards !

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pcbcollection-blog · 7 years ago

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Things We May Consider About When Decides To Do Assembly Work

Whether you're running a tech startup or you've been in business a long time, you might assume that assembling your printed circuit boards in-house is the way to go. After all, you might say to yourself, this is the best way to ensure total control over the quality of my PCBs. Unfortunately, trying to handle PCB assembly yourself will likely backfire. Instead of producing superior PCBs, you may end up with subpar products and higher costs.

You might not relish the thought of outsourcing your design, but it's actually one of the best ways to keep your expenses low, while getting the best quality. Here's why.

It's more cost-effectiveMany businesses mistakenly believe that the best way to cut costs is to do everything in-house. But that's simply not the case. If you aren't an expert, your boards may be more prone to errors -- and fixing those errors can be time-consuming and costly. Plus, you won't be able to produce boards as quickly. Many PCB assemblers are able to have a turnaround time of five days or less, which is 75% faster than the industry average. If you take twice or three times as long to produce your PCBs, you're losing money. Finally, outsourcing these needs to a turnkey PCB company will free up your time to devote to other aspects of your design. The product will be of higher qualityAs we mentioned before, outsourcing your printed circuit boards will give you higher quality. Your PCB assembly house likely has access to the machinery, tools, and knowledge that you simply do not. Because PCB assembly shops employ people who are leaders in their field and own inspection equipment that allows them to catch errors quickly, their products are above and beyond what you can create yourself. And because these PCB turnkey solution providers can offer a one-stop-shop approach, you won't have to worry about taking on any other part of the process and risk negatively impacts the overall quality of the completed projects. When you want to save money and improve the quality of your products, the DIY route can often be a mistake. Instead, consider outsourcing your needs to a turnkey PCB provider that can offer everything you need for an affordable rate

During the assembly process, the designers may concern more about the technology for the assembly fab, The Chinese manufactuer ALLPCB.com,we can look over their plant and machine and learn more about their capability.

For SMT，There are three production lines in the ALLPCB fab .

First one is mannual work line.Once they get the boards and stencils.the paste will be brushed by man hand, and put into the production line for assembly.The manual work lines are normally used for prototype orders with less parts soldered .

The second is the semi-auto production lines.The boards will be put on the machine by ALLPCBworkers , the paste will be brushed by the machine.Then comes the soldering process.

The third line is the auto production lines.The boards will be put in the tray directly , and will be transfered to the paste brushing process, soldering process automatically .

Normally the SMT parts are put in particular feeder ,for 0603,0805, 0402 package ect. And for some special parts, those will be put in another machine with individual pallet .

That’s all the three lines for SMT in ALLPCB , and for SMD part, those are all performed by manual work at present .

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pcbcollection-blog · 7 years ago

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Some Common Design For Manufacturing Mistakes

Designing a PCB layout is hard enough, especially when you’re trying to smash in all of that functionality into an enclosure that seems to shrink more and more with every new board design. But then you have a manufacturer breathing down your neck at the end of the line, telling you that this is too small, that’s too thin, that component doesn’t match. Aren’t you just tired of the back and forth? Guess what, so is your manufacturer!

This is where Design for Manufacturing (DFM), can make everyone’s life a whole lot easier. Think of it as a kind of risk management, a personal insurance that ensures that what you spend hours designing can actually be made at the end of the day. Because whether you like it or not, you can make the best PCB in Autodesk EAGLE, but if that board of yours can’t be made, then it’s all for nothing. So instead of fighting with your PCB manufacturer for each and every mil, just start your design process off right by not making these 10 DFM mistakes that every manufacturer hates.

#1 – Not Leaving Enough Edge Clearance

Here’s the problem with copper, while it might be a great conductor, it’s also prone to corrosion from the environment. To combat this, your manufacturer coats it with a protective material. But what happens if you don’t leave enough space between the edge of your board and your copper? That protective coating can get cut off in the manufacturing process, exposing the copper beneath, and then you’re just waiting for a disaster to happen, like an unintended short or corrosion.

This problem is an easy one to fix. Ensure that you’re leaving enough space between the edge of your copper and the edge of your PCB. That’s a minimum of 0.010” inches for outer layers, and 0.015” for inner layers. You can even plug these clearances into your design rules (DRC), so you’ll never need to worry about it again after you start your PCB layout.

#2 – Making Acid Traps

We all likely know by now not to use any acute angled traces in our PCB layout, opting instead for 45 degree angled traces instead of 90. This helps to prevent any acid from getting trapped during the PCB etching process, and in turn helps to prevent any serious circuit defects down the road.

But time and time again, PCB designers forget one simple thing, you can still make acute angle acid traps from the joining of two traces. Do yourself a favor and thoroughly scan all of the trace angles on your board after you finish your routing. Are you unintentionally creating an acid trap from the joining of two traces even if you used 45 degree routes? It happens, but fix it before your manufacturer ever gets your design files.

#3 – Placing Vias in Pads

It can be really tempting to throw a via inside a pad when your board space is getting tight. But what you might now know is that when it comes time for soldering, that via-in-pad will actually draw solder away from the pad, causing the attached component to be mounted poorly.

While this one-off special technology is certainly useful in the right circumstances, only use it if it’s absolutely necessary. This also holds true for micro vias, blind vias, and buried vias. If there’s an alternative, use it!

#4 – Overcomplicating Your Board Layout

If you’re struggling to place all of your SMT components on the same side of your board and are thinking of place a few on the bottom, stop right there. Not only is this going to cost you twice as much, but it’s also going to be a pain for your manufacturer to run your board not once, but twice, through their pick and place machine.

No one likes throwing money away during manufacturing, so take the time during your PCB layout process to place all of your SMT and through-hole components on the same side of your board. Your manufacturer will thank you later, and so will your wallet.

#5 – Sending an Incomplete Pick and Place File

Chance are if you’re placing SMT components then you’ll need to send your manufacturer a pick and place file. This file tells a pick and place machine exactly where every part needs to be placed on your board. But when was the last time you verified the data this file generates? And is it even complete?

It’s a manufacturer’s worst nightmare when the pick and place file a designer sends over doesn’t include all the information they need to place parts properly. At the very least, be sure to include the following:

Component Reference Designator (e.g., C1)

Component Part Number (e.g., 100CAP0001)

Component Description (e.g., C04020 1uF Electrolytic)

Manufacturer Part Number (e.g., CRD0402D10L)

Mid Point X(mm) (e.g., 10.242)

Mid Point Y(mm) (e.g., 23.750)

Orientation Angle (e.g., 290)

PCB Layer Side (e.g., Top)

#6 – Not Verifying Your Layers

You might think that your design process is done once you mash the generate button on your Gerbers, but hold up! There’s still another step to take. Manufacturers occasionally get shipped Gerber files with board layers that don’t even match up, because we ll know a 30 year old file format isn’t perfect.

Before sending your design files off to your manufacturer take the time to open them in a free third party Gerber viewer to ensure that all of your layers matchup. If they don’t, then you’ll likely need to generate your output documentation again or make some adjustments to your layout.

#7 – Using Multiple Tool Sizes

We all need drill holes and vias on our boards, but are you the guy that decides to make half of your holes 37 miles, and the other half 38 mils? Why? This just requires another set of tool sizes that your manufacturer has to swap in, and it eats away into your wallet in the process.

Instead of having multiple hole and via sizes, just keep them all the same. For standard 0.062” material you can use a via hole size of 13.5 mil and a drill hole size of 37 mil. Having the same size for holes and vias will also make it easy if you need to add more in the future.

#8 – Putting Silkscreen on Pads

We know, you’ve got a ton of different layers on your board, and it’s easy to miss if you accidentally place your silkscreen on top of a pad. But what you might not know is that having silkscreen on a pad can make the soldering process a lot more difficult for your manufacturer.

As a general rule, always keep your silkscreen at least .003” away from your solder mask. And when you’re double checking your PCB layout at the end of your design process, make sure that you have all the layers turned on in EAGLE to show you the full dimensions on your pads.

#9 – Not Adding Solder Mask Between Pads

Solder mask has the important job of insulating all of your copper from accidental contact with other metals. If you don’t place any solder solder between your pads, then you’re just waiting for an opportunity for a solder bridge to form. And then you’ll be wondering why your PCB keeps short circuiting.

To prevent this from happening, always make sure that you define your solder mask requirements in your design rules (DRC), especially when you’re carrying settings over from a larger board to a smaller one. And if you’re working with tightly spaced components like small pin pitch devices, give your PCB layout a double check for solder mask placement before sending any files off to your manufacturer.

#10 – Adding the Wrong Size or Shaped Footprints

Are you sure that the component you just added to your Bill of Materials (BoM) will fit on the pad you placed on your PCB? If you’ve got the wrong sized footprint for your component, then you’ll likely wind up with parts that break during assembly or don’t properly solder.

When making footprints for your parts, always ensure that you’re designing them to IPC standards. This way your physical parts and footprints will always match, and you won’t run into any unnecessary delays during assembly.

Now we have sumarized the top ten design mistakes you may have during the PCB design process, At the same time what is also helpful that a group of engineers can help to review your design before fabrication .ALLPCB.COM is a Chinese PCB manufacturer that provides top-speed PCB fabrication, Other than PCB fabrication, they also pay much attention to the customer’s design experience,they provides a big community that enables you to discuss and share projects with other engineers.You can leave your questions or confusions on ALLPCB community, and wait for reply from other professional engineers !

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pcbcollection-blog · 7 years ago

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PCB Assembly Process Steps

Summary: Originally, all PCBs were assembled by hand using only a solder iron. As technology progresses, components get smaller and more difficult to assemble by hand and the amount of components that may fit on a single board increases. Thus the need for auto assembly was developed.

Surface Mount Assembly Process

Originally, all PCBs were assembled by hand using only a solder iron. As technology progresses, components get smaller and more difficult to assemble by hand and the amount of components that may fit on a single board increases. Thus the need for auto assembly was developed.

REQUIRED ELEMENTS

The following are the required elements for auto assembly:

Gerbers in 274-X (embedded apertures) including fabrication drawing.

Part centroid text file with Reference Designators, external placement layer, and X & Y location and rotation in ASCII format.

Numerical control (NC) drill files

Solder paste file (one of the Gerber files) for all sides mounted

Glue dot file

If possible, the design database, specifying the database format (program name)

Parts list or BOM (bill of material)

Parts or hardware required

Gerbers in 274-X (embedded apertures) including fabrication drawing.

Part centroid text file with Reference Designators, external placement layer, and X & Y location and rotation in ASCII format.

Numerical control (NC) drill files

Solder paste file (one of the Gerber files) for all sides mounted

Glue dot file

If possible, the design database, specifying the database format (program name)

Parts list or BOM (bill of material)

Parts or hardware required

The Gerber files are used to define the pad locations and help the assembly house determine where pin 1 is located and provides a heads-up of how the board looks. The database can also be used to determine the location of pin 1. Some board houses choose to make their own solder paste file/stencil. The designer may create the solder paste file to his/her own preference with experience. It is good to learn how and why the assembly house makes its stencils and duplicate it to ensure consistency from each assembly house (the common name for any company that assembles boards). The solder paste file is used to mask the entire board except those areas that will be soldered. Solder paste is applied to the exposed pads and the stencil is removed. Components are applied and held to the board by the solder paste and the glue dots securing the components as they are soldered to the board.

For component placement a part placement/centroid file is required to know where the center of the part is. The layer ID shows what side the part is placed on, and the rotation displays the orientation of the component.

Consistency in rotation of the original component is critical to report. Unless the designer's software can account for inconsistencies, all components should be created in the same orientation.

NC drill files are used to locate mounting holes and provide the holes sizes for thru-hole components. This also allows the assembly house to determine adequate clearance for the component lead.

A bill of material or parts list is used to reference the designators of the centroid file and the components that need to be mounted. The BOM should also provide information if the component is an SM component or a thru-hole component.

OTHER CONSIDERATIONS

Other considerations for auto assembly are the board size, the panel size, and breakaways. The boards are commonly assembled in a panel that may contain many boards. The panel is the original material that the boards were etched routed in. The panels pass to the assembly house with all boards intact.

1.ORDERING A BOARD

You can find a manufacturer to fabricate, Like ALLPCB.com,they provide one-Stop Solution for PCB & Prototype Assembly,

2.DFM CHECK

The DFM check looks at all the design specifications of a PCB. Specifically, this check looks for any missing, redundant or potentially problematic features. Any of these issues may severely and negatively influence the functionality of the final project. For example, one common PCB design flaw is leaving too little spacing between PCB components. This can result in shorts and other malfunctions. By identifying potential problems before manufacturing begins, DFM checks can cut manufacturing costs and eliminate unforeseen expenses. This is because these checks cut down on the number of scrapped boards. As part of our commitment to quality at a low cost.

3.INCOMING QUALITY CONTROL(IQC)

ALLPCB Verifying all incoming materials and handling quality problems before subsequent SMT assembly begins. Our IQC position will check following issues of incoming materials if they comply with our strict requirements.

A: model number and quantities according to BOM list

B: shape (deformation, broken pin, oxidation etc), particularly for IC or other complex components

C: sample test of incoming materials by tools such as test frame, multimeter etc.

D If above defect or discrepancy occurs, we will return full incoming materials to supplier or customer.

4.MACHINE PROGRAMMING - GERBER / CAD TO CENTROID / PLACEMENT / XY FILE

Having received the PCB panels and components the next step is to setup the various machines used with the manufacturing process. Machines such as the placement machine and AOI (Automated Optical Inspection) will require a program to be created which is best generated from CAD data but quite often this isn't available. Gerber data is almost always available as this is the data required for the bare PCB to be manufactured.

5.SOLDER PASTE PRINTING

The first machine to setup in the manufacturing process is the solder paste printer which is designed to apply solder paste using a stencil and squeegees to the appropriate pads on the PCB.

6.COMPONENT PLACEMENT

Once the printed PCB has been confirmed to have the correct amount of solder paste applied it moves into the next part of the manufacturing process which is component placement. Each component is picked from its packaging using either a vacuum or gripper nozzle, checked by the vision system and placed in the programed location at high speed.

There is a large variety of machines available for this process and it depends greatly on the business to what type of machine is fingers and clothing to the surface of the board. Once all is said and done, the results can look a little dingy, which is both an aesthetic and a practical issue.

For SMT，There are three production lines in the fab .

The second is the semi-auto production lines.The boards will be put on the machine by workers , the paste will be brushed by the machine.Then comes the soldering process.

The third line is the auto production lines.The boards will be put in the tray directly , and will be transfered to the paste brushing process, soldering process automatically .

Normally the SMT parts are put in particular feeder ,for 0603,0805, 0402 package ect. And for some special parts, those will be put in another machine with individual pallet .

That's all the three lines for SMT , and for SMD part, those are all performed by manual work at present .

After the SMT SMD , the boards will be tested , for testing ,there is visual inspection(this is also conducted during the SMT process）, AOI test (to see if there is any inveracious soldering, missing parts ect.)electronical test( for LED to test the lighting function ect).

Hopefully the essay explains the whole process while and helps to have a better and clearer understanding of the assembly process !

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pcbcollection-blog · 7 years ago

Text

PCB Assembly Process Steps

Surface Mount Assembly Process

REQUIRED ELEMENTS

The following are the required elements for auto assembly:

Gerbers in 274-X (embedded apertures) including fabrication drawing.

Part centroid text file with Reference Designators, external placement layer, and X & Y location and rotation in ASCII format.

Numerical control (NC) drill files

Solder paste file (one of the Gerber files) for all sides mounted

Glue dot file

If possible, the design database, specifying the database format (program name)

Parts list or BOM (bill of material)

Parts or hardware required

Gerbers in 274-X (embedded apertures) including fabrication drawing.

Part centroid text file with Reference Designators, external placement layer, and X & Y location and rotation in ASCII format.

Numerical control (NC) drill files

Solder paste file (one of the Gerber files) for all sides mounted

Glue dot file

If possible, the design database, specifying the database format (program name)

Parts list or BOM (bill of material)

Parts or hardware required

Consistency in rotation of the original component is critical to report. Unless the designer's software can account for inconsistencies, all components should be created in the same orientation.

NC drill files are used to locate mounting holes and provide the holes sizes for thru-hole components. This also allows the assembly house to determine adequate clearance for the component lead.

OTHER CONSIDERATIONS

Note

Breakaways are the connections around a board that hold the board during assembly but can be broken easily when it is time to remove the board.

1.ORDERING A BOARD

You can find a manufacturer to fabricate, Like ALLPCB.com,they provide one-Stop Solution for PCB & Prototype Assembly,

2.DFM CHECK

3.INCOMING QUALITY CONTROL(IQC)

A: model number and quantities according to BOM list

B: shape (deformation, broken pin, oxidation etc), particularly for IC or other complex components

C: sample test of incoming materials by tools such as test frame, multimeter etc.

D If above defect or discrepancy occurs, we will return full incoming materials to supplier or customer.

4.MACHINE PROGRAMMING - GERBER / CAD TO CENTROID / PLACEMENT / XY FILE

5.SOLDER PASTE PRINTING

The first machine to setup in the manufacturing process is the solder paste printer which is designed to apply solder paste using a stencil and squeegees to the appropriate pads on the PCB.

6.COMPONENT PLACEMENT

For SMT，There are three production lines in the fab .

The second is the semi-auto production lines.The boards will be put on the machine by workers , the paste will be brushed by the machine.Then comes the soldering process.

The third line is the auto production lines.The boards will be put in the tray directly , and will be transfered to the paste brushing process, soldering process automatically .

Normally the SMT parts are put in particular feeder ,for 0603,0805, 0402 package ect. And for some special parts, those will be put in another machine with individual pallet .

That's all the three lines for SMT , and for SMD part, those are all performed by manual work at present .

Hopefully the essay explains the whole process while and helps to have a better and clearer understanding of the assembly process !

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pcbcollection-blog · 7 years ago

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6 Best PCB Design Software of 2018

Before the PCBs are fabricated out in the PCB manufacturer, the most important is to design your PCBs out .There are many circuit software systems available to meet the various appearance requirements, including free design software for PCBs, free software for, and PCB design industrial PCB software. Check out the list of PCB design software and a short introduction. You can make a comparison based on the introduction.

Printed circuits are very important to the design and manufacture of electronic circuit boards and printed circuit boards, which serve as the basis for supporting the electronic elements and components and providing the required polarization and signal path components.

PROTEL (Altium Designer) This is the best PCB design software, the company showcases the design port circuits (CAD) for the district sector in the late eighties and twenties of the 20th century, consistently rated high among many EDA software and software preferred circuit designers.

Many specialized disciplines within universities have special courses to learn how to use the mind and almost every business that is used for their work.It is good for the advice of one or two layers. However, it is a bit difficult to use when it comes to more than four layers, not to mention the PCB design in the transmission of high-frequency signals and high-speed scan.

PADS (PowerPCB) You can describe it for the CAD king on the low side. For me, this is the best among similar EDA EDA because of the ease of use, easy to learn. The quality of the design wouldn’t be worse than that of the WG, Allegro. It is most commonly used in the EDA market and is also very suitable for small businesses.

Provides a very intuitive and easy-to-use environment, ideal for a less complicated project panel where the priority costs. PADS has expanded the functionality of simulation and analysis, and advanced features, high-quality fast PCB products.

OrCAD OrCAD is a unique set of software tools mainly used for electronic design automation (EDA). The software is mainly used by electronic engineers and electronics engineers in the electronic card, and electronic fingerprints for the production of printed circuit boards are designed.

ORCAD is EDA software developed by ORCAD in the late 1980s that is old as Protel, but worse than Protel. The ORCADov principle is very popular in the industry because of its friendly face, ease of use and powerful simulation function. In comparison with the DX designer, I agree with Orcad. But the DX designer has a better management function, a better-integrated environment.

WG It belongs to the mentor of the WG. WG 2005 was introduced on Windows basis. The layout comes first to determine if it is good software if there are obvious advantages and disadvantages for the secondary and tertiary market. I have to say that WG2005 is fantastic in appearance, it can be said that the king seems to have a strong position in the calendar and programming rules are very professional. ExpeditionPCB of WG core and WG 2005 contain DX, DC, DV, LIB, EXP.

Free PCB FreePCB is a free, open-source PCB editor for Microsoft Windows, released under the GNU General Public License. Designed to be easy to learn and easy to use, but capable of professional work.

1 to 16 copper layers

Board size up to 60 inches to 60 inches Import and export of PADS PCB netlists Export advanced Gerber files (RS274X) and Excellon drill files Check the design rule Save Automatically

Eagle

PCB Autodesk Eagle design software is powerful and easy to use tool for all engineers and offers a free version, and the paid version is not easy to use circuit diagram editor, PCB powerful and ready to use layout part of the library and this software is suitable best for complex PCB projects.EAGLE is scriptable electronic design automation (EDA) with a schematic recording, the appearance of printed circuit boards (PCB), automatic routers and computer manufacturing (CAM). EAGLE means easy-to-use graphical editor, and was developed by CadSoft Computer GmbH the company was acquired by Autodesk in 2016

The above six software are favored by different designers, and ALLPCB.COM, a Chinese manufacturer is planning to release video lessons and teach beginers how to design PCBs, how to perfect designs,how to add traces, how to define vias ect.The relative lessons will be based on Eagle software this time.They provide subtitles in both Chinese and English version, The video is estimated to release on https://www.allpcb.com/ around September.Hopefully it is helpful for green hands who want to begin the PCB designs!

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