How to Avoid CAM Hold:

1. The most effective way to avoid having your order go on CAM hold is to take advantage of FreeDFM.com. You will get the following benefits:

2. Free PCB design file check for manufacturability

3. We check to make sure we have the files and data necessary to build your job

4. Results e-mailed to you in minutes

5. You get a graphical report, showing any potential issues with detail as to their nature and location

6. Reduces possibility of CAM Hold issues after order placement

7. Enables 48% faster total thru-put from order placement to shipment

8. Also provides a price quote with your choice of turntimes

Creating Gerber files that accurately reflect what you want manufactured is a challenge no matter how long you have been a PCB designer. However, by learning from others and avoiding the most common mistakes, you can speed up the turnaround time, reduce the chance of orders placed on hold, and complete your projects faster. The following list reviews the top seven most common mistakes made with Gerber files and how you can avoid them.

1. Missing Aperture List
Your Gerber files specify what to do and where. Your aperture list specifies what tool to use. A single comprehensive aperture list for all layers should be sent with your gerber files, rather than a separate aperture list for each layer. Please note: An aperture list does not need to be sent with 274X format files. If you send 274D format, we use your aperture list in combination with your gerber files to create your artwork.

Requirements: One comprehensive aperture list for all layers, English Units. Please do not modify the aperture list your software outputs. An aperture list does not need to be sent with 274X format files.

Resolution: All layout packages which output 274D also output an aperture list. Common extensions include .rep, .apt, and .apr. If you have difficulty outputting an aperture list, please send 274X format.

2. Missing Excellon Drill File
Excellon drill files are used to determine what size holes to drill and where. Plated and non-plated holes need to be included in one drill file, with plated and non-plated holes having different tool numbers.

Requirements: Excellon Format, ASCII Odd/ None, 2.4 Trailing Zero Suppression, English Units, No Step and Repeats.

Resolution: Nearly all layout packages will output an Excellon drill file. If you cannot generate one, we can in most cases create one from your fabrication drawing for an engineering fee.

3. Missing Tool List
A tool list is used in combination with your Excellon drill file to create your drill. Your drill file specifies where to place the holes. Your tool list specifies what tool to use. A tool list should be embedded in your Excellon drill file or sent as a separate text file. Using a tool list provided on a fabrication drawing is not preferable, as it eliminates many of the automatic verifications and makes data entry errors far more likely.

Requirements: Tool list embedded in Excellon drill file or sent as a separate text file.

Resolution: If your layout software will output an Excellon drill file, it will also output a tool list. Common extensions include .tol and .rep.

4. Missing Gerber Files
Believe it or not, many times people submit orders and forget to attach their Gerber files.

Requirements: Gerber 274X or 274D, English units are preferable.

Resolution: ODB++ files are acceptable; however, these files should be sent to odb@4pcb.com. It is possible to convert many other file formats to Gerber. Please send your non-Gerber formats to convert@4pcb.com.

5. Insufficient Annular Ring
An annular ring is the donut (”annulus”) created when your drill pierces a copper layer. It is defined as the radius of this donut. For example, a .030″ pad with an .020″ hole would have a .005″ annular ring. This is required to allow for complete plating on vias, as well as solderability on component holes. Many times people do not allow for the proper annular ring requirements.

Requirements: A minimum of .005″ annular ring for vias or a minimum of .007″ for component holes is required for manufacturing.

Resolution: All layout packages provide this as a DFM check. Setting sufficient annular ring in your layout software is the preferred method in order to maintain proper copper spacing.

6. Insufficient Copper Trace Width/Spacing
Copper spacing is the minimum air gap between any two adjacent copper features. Trace width is the minimum width of a copper feature, usually traces.

Requirements: A minimum of .005″ trace width/spacing is necessary. A premium is charged for trace width/spacing less than .007″.

Resolution: All layout packages provide this as a DFM check. Setting sufficient trace width/ spacing in your layout software is the preferred method. Trace width and spacing push and pull against one another, so changing a problem area may require rerouting traces, adding vias, or moving components.

7. Insufficient Inner Clearances
Inner clearance is the minimum distance from the edge of a hole to any adjacent, unconnected, inner layer copper. Sufficient inner clearances help ensure that your drill does not cause shorts to your inner copper layers. This is important for both plated and non-plated holes, as non-plated holes may either cut into an adjacent trace or cause shorts during assembly.

Requirements: A minimum of .010″ inner clearance is required and .015″ is preferred.

Resolution: Most inner clearance issues can be resolved if negative image inners are provided, but it is preferred to not modify these. Setting these clearances in your layout software is the preferred method, as this will maintain intended connectivity. While most layout packages provide this as a DFM check, not all do. Those that do not can usually be manipulated to check for this violation by setting spacing and annular ring higher.

General guidelines: Spacing + Annular ring = Inner clearance. Another trick that can help resolve problem areas is to move the affected traces to outer copper layers, where this is not an issue.

This article was written for the Nov 2007 issue of Electronic Products
PCB layout tool is offered free of charge

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Information 800-979-4722 ext. 691
layouthelp@4pcb.com
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ADVANCED CURCUITS ROLLS OUT THE “GOLD” CARPET

Immersion Gold (ENIG) plating line delivers high-quality durable lead-free surface option

AURORA, Colo. – Feb. 20, 2007 – Advanced Circuits, the country’s leading manufacturer of quickturn printed circuit boards, today announced that it has completed installation of its Electroless Nickel Immersion Gold (ENIG) plating line to meet customer demand for the latest in lead-free surface finish technology. The addition of this line to the Advanced Circuits offerings provides a superior quality lead-free printed circuit board option for Advanced Circuits customers.
ENIG plated printed circuit boards are more durable, aluminum wire bondable and provide an excellent electrical contacting surface. Additionally, with ENIG, the PCB’s shelf life can exceed 12 months. Aiding the manufacturing process, ENIG boards are easy to visually inspect, and the thickness can be easily verified by non-destructive measurement.
“Although we lead the industry in turn time and product quality, we are constantly striving to provide the very best products and technology for our customers. With the addition of the ENIG plating system, and immersion silver which will follow, we are pleased to provide our customers with the option to choose from a selection of lead free, quickturn plating alternatives,” said John Yacoub, Advanced Circuits president and CEO.
Recent developments regarding RoHS (Restriction on Use of Hazardous Substances in Electrical and Electronic Equipment) have spurred interest in and demand for ENIG technology, which enables complete management of the plating process from a single location while maintaining safety, environmental conditions and waste control. The new in-house ENIG capability will allow Advanced Circuits to provide expedited turntimes for customers, as well as the one-day turns that the company is known for.

Creating Gerber files that accurately reflect what you want manufactured is a challenge no matter how long you have been a pcb designer. However, by learning from others and avoiding the most common mistakes, you can speed up the turnaround time, reduce the chance of orders placed on hold, and complete your projects faster. The following list reviews the top seven most common mistakes made with Gerber files and how you can avoid them.

1. Missing Aperture List
Your gerber files specify what to do and where. Your aperture list specifies what tool to use. A single comprehensive aperture list for all layers should be sent with your gerber files, rather than a separate aperture list for each layer. Please note: An aperture list does not need to be sent with 274X format files. If you send 274D format, we use your aperture list in combination with your gerber files to create your artwork.

Requirements: One comprehensive aperture list for all layers, English Units. Please do not modify the aperture list your software outputs. An aperture list does not need to be sent with 274X format files.

Resolution: All layout packages which output 274D also output an aperture list. Common extensions include .rep, .apt, and .apr. If you have difficulty outputting an aperture list, please send 274X format.

2. Missing Excellon Drill File
Excellon drill files are used to determine what size holes to drill and where. Plated and non-plated holes need to be included in one drill file, with plated and non-plated holes having different tool numbers.

Requirements: Excellon Format, ASCII Odd/ None, 2.4 Trailing Zero Suppression, English Units, No Step and Repeats.

Resolution: Nearly all layout packages will output an excellon drill file. If you cannot generate one, we can in most cases create one from your fabrication drawing for an engineering fee.

3. Missing Tool List
A tool list is used in combination with your excellon drill file to create your drill. Your drill file specifies where to place the holes. Your tool list specifies what tool to use. A tool list should be embedded in your excellon drill file or sent as a separate text file. Using a tool list provided on a fabrication drawing is not preferable, as it eliminates many of the automatic verifications and makes data entry errors far more likely.

Requirements: Tool list embedded in excellon drill file or sent as a separate text file.

Resolution: If your layout software will output an excellon drill file, it will also output a tool list. Common extensions include .tol and .rep.

4. Missing Gerber Files
Believe it or not, many times people submit orders and forget to attach their gerber files.

Requirements: Gerber 274X or 274D, English units are preferable.

Resolution: ODB++ files are acceptable; however, these files should be sent to odb@4pcb.com. It is possible to convert many other file formats to gerber. Please send your non-gerber formats to convert@4pcb.com.

5. Insufficient Annular Ring
An annular ring is the donut (“annulus”) created when your drill pierces a copper layer. It is defined as the radius of this donut. For example, a .030” pad with an .020” hole would have a .005” annular ring. This is required to allow for complete plating on vias, as well as solderability on component holes. Many times people do not allow for the proper annular ring requirements.

Requirements: A minimum of .005” annular ring for vias or a minimum of .007” for component holes is required for manufacturing.

Resolution: All layout packages provide this as a DFM check. Setting sufficient annular ring in your layout software is the preferred method in order to maintain proper copper spacing.

6. Insufficient Copper Trace Width/Spacing
Copper spacing is the minimum air gap between any two adjacent copper features. Trace width is the minimum width of a copper feature, usually traces.

Requirements: A minimum of .005” trace width/spacing is necessary. A premium is charged for trace width/spacing less than .008”.

Resolution: All layout packages provide this as a DFM check. Setting sufficient trace width/ spacing in your layout software is the preferred method. Trace width and spacing push and pull against one another, so changing a problem area may require rerouting traces, adding vias, or moving components.

7. Insufficient Inner Clearances
Inner clearance is the minimum distance from the edge of a hole to any adjacent, unconnected, inner layer copper. Sufficient inner clearances help ensure that your drill does not cause shorts to your inner copper layers. This is important for both plated and non-plated holes, as non-plated holes may either cut into an adjacent trace or cause shorts during assembly.

Requirements: A minimum of .012” inner clearance is required and .015” is preferred.

Resolution: Most inner clearance issues can be resolved if negative image inners are provided, but it is preferred to not modify these. Setting these clearances in your layout software is the preferred method, as this will maintain intended connectivity. While most layout packages provide this as a DFM check, not all do. Those that do not can usually be manipulated to check for this violation by setting spacing and annular ring higher.

General guidelines: Spacing + Annular ring = Inner clearance. Another trick that can help resolve problem areas is to move the affected traces to outer copper layers, where this is not an issue.

1. Placing vias by the stiffener area or where the flex bends which can cause via cracking.
2. Not showing the overall thickness of the stiffener area. It is important that you show the x & y dimensions of the stiffener, show placement on the flex, and dictate whether the material is Kapton or FR4.
3. Failing to state a tolerance on the overall thickness of the stiffener area. The tolerance specified should not be less than +/- 10% of the overall thickness in this area.
4. Bending a flex circuit 90 degrees. See “Minimum Bend Radii for Flex Circuits” chart for guidelines.
5. Not showing the stackup. (Should indicate base material, copper thickness, cover layer thickness, as well as stiffener material and thickness.)
6. Failing to indicate copper weight. When specifying copper weight, it is important that you state whether you are indicating base material copper or finished copper weight.
7. Having silkscreen nomenclature less than .008″ which can cause illegibility or placing silkscreen too close to exposed pad areas. Silkscreen should be no closer than .010″.
8. Not indicating the total thickness of the flex and tolerance.
9. Placing edge of trace closer than .015″ to edge of board.
10. Making hole opening on stiffener too small. Should be +.010″ over finished pad size.

Advanced Circuits stencils are 100% laser-cut type 304 full-hard stainless steel, ensuring the finest quality finish on the market today. We use a .001″ laser beam with 98% overlap creating an extremely smooth hole that provides the best paste release. Most stencil fabricators use a .003″ laser leaving mouse bites on the aperture edge. You can choose a prototype “DESKTOP®” stencil, a frameless foil stencil, or a rigid permanently mounted stencil. Both the frameless and framed stencils come in various sizes to accommodate your printer and stencil requirements.

Stencil Types Available:

a. DESKTOP® (Low-volume manual printing. Ideal for prototypes)
When prototyping dictates fast action with minimal cost, our DESKTOP® stencils are the best solution. A DESKTOP® Stencil gives you a quality stencil and framework so you can handle assembly from the convenience of your own desk. Click here for more details on how to use DESKTOP® Stencils.

b. Framed (Also called “Glue-in” or Mounted Stencils)
Framed stencils are laser-cut stencils designed for high volume screen-printing. With a framed stencil, your stencil is securely mounted to either a cast or extruded aluminum stencil frame a stencil frame using a mesh border, allowing for complete control.

c. Frameless - Foil/Plate Only (for universal frames)
Foil or Plate Only stencils are designed to work within interchangeable plate or “universal” systems. Also referred to as “reusable”, these stencils do not need to be permanently glued into a frame.

d. Frameless - Foil/Plate Only (for hand printing)
For times when you need precise control for smaller production runs, our Foil or Plate Only stencils are ideal. These frameless stencils allow you to handprint with precision just the amount you need and can be stored conveniently.

e. Pro-Frame™ Universal Frame with Foil Our Pro-Frame™ Universal Frame has been a leader in universal frame design. Pro-Frame™ stencils are produced without a frame for use in the ProFrame II ™. They offer convenient shipping and provide money-saving storage – all while still delivering superior quality and performance.

For More Infomation About PCB’s

Advanced Circuits offers a full range of PCB services to ensure every time our customers receive one of our printed circuit boards, it is of the highest quality, offers the most value and is exactly right in every way.

Have a particularly difficult problem? Give us a call at 1-800-979-4PCB. Our experts thrive on challenges that other companies won’t touch.

Standard Manufacturing Capabilities — Printed Circuit Boards
- Materials: FR4
- Double sided technology
- 4, 6, 8, and 10 layer technology
- Printed circuit board final thickness from .020″ to .125″
- Min. trace .0049″ - Min. space .0045″
- Minimum finished hole size .010″
- Finished copper weight from .5 to 3oz
- Printed circuit board surface finish: HASL, Gold, Lead Free Solder, & Bare Copper
- Plated slots and edges
- LPI soldermask in a variety of colors
- Silkscreen/Legend in a variety of colors
- Controlled dielectric
- Scoring, tab, and individual rout
- Minimum inner layer clearance of .010″
- UL listed

Specialized Manufacturing Capabilities, PCB
- Materials: Duroid, Rogers, Polyimide, Teflon, and Kapton
- 12 and 14 layer technology
- Printed circuit board final thickness of < .020"
- Min. trace .004" - Min. space .004"
- Minimum finished hole size .008"
- Finished copper weight of 4 oz
- Printed circuit board surface finish: Soft Gold and White Tin, Immersion Gold
- Controlled Impedance
- Skip (jump) Scoring
- Flex and Rigid Flex technology

Click here to visit the corporate site at http://www.4pcb.com

PCB Manufacturer Overview

Experience Our Convenience to Order Printed Circuit Boards
· On-line pricing in seconds
· “Live” tech assistance anytime
· Track order status and history on-line
· No pcb order too small
· Expedites are a specialty

Experience Our Reliability
· Protos shipped on time…or they’re FREE!
· Industry’s best on-time shipping record
· 50% of orders shipped early

PCB’s Advanced Circuits Customer Comments
At Advanced Circuits, we are motivated every day to delight our customers with printed circuit boards that consistently exceed all expectations. Our customers trust us to deliver the highest quality PCB’s at fair prices, on time or faster.

“When I provide Gerber files that have been “pre-checked” by your FreeDFM service, I know my clients will not have unwelcome delays getting their boards produced. FreeDFM eliminates those problems that can translate into days lost on the schedule.” — R.P., Capital Products Design.

“I just went through 3 submissions to FreeDFM which each time found problems, and now the file is correct. You have done all of us dweebs a great service by providing FreeDFM!” — L. S., Goldline Controls

“DFM worked great! The files were interpreted correctly on the first try, it even caught my silkscreen error. The .pdf files showing the interpreted results of my gerber files were excellent, very clear, detailed, as good as any checkplots I’ve every seen. ” — S. M., Mann Electronic Solutions.

“Nowadays it is rare to find vendors that provide quality products, exceptional delivery, all at a competitive price. AC possesses all of these attributes along with exceptional customer service.” — S.S., Edmunds GAGES

“The CAM guys are awesome on the telephone working out answers to questions we have. All in all, I think you guys are the best!” — B. H., Lord Corp.

“Thank you for getting these boards ahead of time. Thanks to you our allotted assembly time has tripled….and we now have a chance to meet our accelerated deadline.” — J.D., Microfabrica.

“We have thousands of photonic assemblies with AC boards in them that are used around the world and we have never had one single unit returned because of a PCB failure. ” — B.H. Displaytech

“I was quite impressed with fab managers even calling me past 9 pm to obtain a clarification on a board issue that arose. This is the first time I’ve ever been able to straighten out a fast-turn PCB order from the middle of a shopping-mall food court. ” — C.L. MIT

“The quality, price, and delivery your organization delivers day in and day out is impeccable. ” — J.W., PCB consultant